JP2015146357A - Electrode connection set, manufacturing method of solar cell, solar cell, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode connection set capable of obtaining excellent adhesion between an electrode and a wiring member and excellent connection reliability.SOLUTION: The electrode connection set includes: a composition for an electrode containing phosphorous-tin-containing copper alloy particles and glass particles; and a connection material containing an adhesive.

Description

  The present invention relates to an electrode connection set, a solar cell manufacturing method, a solar cell, and a solar cell module.

  In general, electrodes are formed on a light receiving surface and a back surface of a solar cell element including a semiconductor substrate such as a silicon substrate. In order to efficiently extract the electric energy converted in the solar cell element by the incidence of light to the outside, the volume resistivity of the electrode is sufficiently low, and the electrode forms a good ohmic contact with the semiconductor substrate. It is necessary.

The electrodes used in the solar cell element include a light receiving surface current collecting electrode, a light receiving surface output extraction electrode, a back surface current collecting electrode and a back surface output extraction electrode, and are usually formed as follows. When an electrode is formed using a p-type silicon substrate which is a kind of semiconductor substrate, a texture (unevenness) is formed on the light-receiving surface side of the p-type silicon substrate, and then phosphorus or the like is thermally diffused at a high temperature. An electrode composition (sometimes referred to as an electrode paste composition) is applied on the n ⁺ -type diffusion layer by screen printing or the like, and is fired at 800 ° C. to 900 ° C. in the atmosphere. An electrode is formed. The electrode composition forming these electrodes contains conductive metal powder, glass particles, various additives and the like.

Silver particles are generally used as the conductive metal powder other than the back surface collecting electrode among the electrodes. The use of silver particles requires that the volume resistivity of the silver particles is as low as 1.6 × 10 ⁻⁶ Ω · cm, that the silver particles are self-reduced and sintered under the above-mentioned firing conditions, and that the semiconductor substrate is in good ohmic order. There are advantages such as being able to form a contact (electrical connection).

As described above, the electrode composition containing silver particles exhibits excellent characteristics as an electrode of a solar cell element. On the other hand, since silver is a precious metal and the bullion itself is expensive, and because of the problem of resources, a proposal for a material to replace silver is desired.
A promising material that can replace silver is copper that is applied to semiconductor wiring materials. Copper is abundant in terms of resources, and the cost of bullion is as low as about 1/100 of silver. However, copper is a material that is easily oxidized at a high temperature of 200 ° C. or higher in the atmosphere, and it is difficult to form an electrode in the above process.

  In order to solve the above-mentioned problems of copper, copper particles that have been imparted with oxidation resistance using various methods and are not easily oxidized even when subjected to high-temperature firing have been reported (for example, Patent Document 1 and Patent Document 2). In addition, as a method for suppressing copper oxidation during firing, a method using an electrode paste composition (electrode composition) containing copper-containing particles and glass particles has also been reported (see, for example, Patent Document 3). ).

  Here, the structure of a general solar cell and a solar cell module will be described. A general solar cell element has a size of, for example, 125 mm × 125 mm or 156 mm × 156 mm, and produces a small amount of power alone. Therefore, actually, a plurality of solar cell elements are collectively used as a solar cell and a solar cell module. In many cases, the solar cell and the solar cell module are connected in series and / or in parallel via a wiring member in which a plurality of solar cell elements are electrically connected to the output extraction electrodes on the light receiving surface and the back surface. Have a structure. In addition, since the solar cell module is used in an outdoor environment, the solar cell module includes a plurality of solar cell elements connected via a wiring member as a sealing material in order to ensure resistance to temperature change, wind and rain, snow accumulation, and the like. And sealed. Usually, sealing is performed by a vacuum laminator after a sealing material including tempered glass, an ethylene vinyl acetate (EVA) sheet, a back sheet, and the like is laminated and sandwiched between solar cells having wiring members. In addition, a solar cell element means here what has a semiconductor substrate which has a pn junction, and the electrode formed on the semiconductor substrate. A solar cell means the thing of the state by which the wiring member was provided on the solar cell element and the several solar cell element was connected through the wiring member as needed. A solar cell module means what sealed the solar cell provided with the wiring member with the sealing material so that a part of wiring member in a solar cell may be exposed.

  When connecting the electrode of the solar cell element and the wiring member, it is necessary to reduce the electrical contact resistance between the electrode and the wiring member in order to efficiently extract the electric energy converted in the solar cell element to the outside. There is. Further, when the solar cell module is manufactured, in order to prevent the solar cell element from dropping from the wiring member in the step of transporting the solar cell in a state where a plurality of solar cell elements are connected by the wiring member, It is necessary to firmly maintain the adhesion between the element electrode and the wiring member.

  Generally, solder is used for connection between the electrode of the solar cell element and the wiring member (see, for example, Patent Document 4 and Patent Document 5). Solder is widely used because it is excellent in connection reliability such as conductivity and fixing strength, is inexpensive and versatile. In recent years, lead-free solder has also become widespread as a solder used for connection between the electrode of the solar cell element and the wiring member from the environmental viewpoint.

  On the other hand, a connection method using a conductive paste is disclosed as a connection method that does not use solder (see, for example, Patent Documents 6 to 8).

JP 2005-314755 A Japanese Patent Laid-Open No. 2004-217952 JP 2011-171272 A JP 2004-204256 A JP-A-2005-050780 JP 2000-286436 A JP 2001-357897 A Japanese Patent No. 3448924

However, when lead-free solder is used, since the melting temperature of the solder is usually about 230 ° C. to 260 ° C., the high temperature accompanying the connection or the volumetric shrinkage of the solder affects the semiconductor structure of the solar cell element. It may cause deterioration of the performance of the element.
Furthermore, as described in Patent Document 6, Patent Document 7 or Patent Document 8, the method of connecting the electrode of the solar cell element and the wiring member using a conductive paste is performed over time under high temperature and high humidity conditions. The power generation performance may be greatly deteriorated, and sufficient connection reliability is not always obtained.
On the other hand, when the connection between the copper-containing electrode and the wiring member as described in Patent Document 3 is performed with solder or a conductive paste, the adhesion between the copper-containing electrode of the solar cell element and the wiring member tends to be insufficient. It was.

  The present invention has been made in view of the above problems, and uses an electrode connection set and an electrode connection set capable of obtaining excellent adhesion between the electrode and the wiring member and excellent connection reliability. It aims at providing the manufacturing method of a solar cell, a solar cell, and a solar cell module.

Specific means for achieving the above object are as follows.
<1> An electrode connection set including a composition for an electrode including phosphorus-tin-containing copper alloy particles and glass particles, and a connection material including an adhesive.
<2> The electrode connection set according to <1>, wherein the electrode composition further includes nickel-containing particles.
<3> The electrode connection set according to <1> or <2>, wherein the phosphorus-tin-containing copper alloy particles further contain nickel.
<4> The electrode connection set according to any one of <1> to <3>, wherein the connection material further includes a curing agent and a film forming material.
<5> The electrode connection set according to any one of <1> to <4>, wherein the connection material further includes conductive particles.
<6> The electrode connection set according to any one of <1> to <5>, wherein the electrode composition further includes a dispersion medium.
<7> A step of applying the electrode composition onto a semiconductor substrate having a pn junction, a step of heat-treating the semiconductor substrate to which the electrode composition is applied, and forming a copper-containing electrode, and the copper Any one of <1> to <6> including a step of laminating the connection material and the wiring member on the containing electrode in this order to obtain a laminate, and a step of heating and pressurizing the laminate. The manufacturing method of the solar cell which manufactures a solar cell using the electrode connection set of claim | item.
<8> The method for producing a solar cell according to <7>, wherein the heat treatment is performed at 450 ° C. to 900 ° C.
<9> A solar cell obtained by the production method according to <7> or <8>.
<10> A solar cell obtained by the production method according to <7> or <8>, and a sealing material that seals the solar cell so that a part of the wiring member in the solar cell is exposed. And a solar cell module.

  According to the present invention, an electrode connection set capable of obtaining excellent adhesion between the electrode and the wiring member and excellent connection reliability, a solar cell manufacturing method using the electrode connection set, a solar cell, and A solar cell module can be provided.

It is a schematic sectional drawing which shows an example of the solar cell element concerning this invention. It is a schematic plan view which shows an example of the light-receiving surface side electrode structure of the solar cell element concerning this invention. It is a schematic plan view which shows an example of the light-receiving surface side electrode structure of the solar cell element concerning this invention. It is a schematic plan view which shows an example of the back surface side electrode structure of the solar cell element concerning this invention. It is a schematic plan view which shows an example of the light-receiving surface of the solar cell of this invention. It is a schematic plan view which shows an example of the back surface of the solar cell of this invention. It is a schematic sectional drawing which shows an example of the structure which connected the two solar cells of this invention. It is a figure which shows an example of the cross section of the wiring connection part of the solar cell of this invention. It is a figure for demonstrating an example of the manufacturing method of the solar cell module of this invention.

The electrode connection set of this invention contains the composition for electrodes containing a phosphorus- tin containing copper alloy particle and glass particle, the connection material containing an adhesive agent, and another element as needed.
Since the electrode connection set includes the electrode composition and the connection material in combination, an electrode obtained from the electrode composition using the connection material by further preparing a wiring member; The wiring member can be connected. In the solar cell obtained by using this set in which the electrode obtained from the electrode composition and the wiring member are connected, the wiring connection portion between the electrode and the wiring member has high connection strength (adhesion). And high connection reliability.

This can be considered as follows, for example.
The copper-containing electrode formed by the heat treatment (firing) of the electrode composition of the electrode connection set of the present invention includes a metal part showing an alloy phase containing copper and tin, such as a Cu-Sn alloy phase, and Sn-PO glass. It is comprised by the glass part containing tin, phosphorus, and oxygen, such as a phase. Among these, the Cu—Sn alloy phase forms a dense bulk metal portion. Moreover, the space | gap part in which the metal part and the glass part are not formed arises in an electrode. This is presumably because the reaction during the formation of the bulk metal part and the sintering of the alloy phase proceed dramatically. It is preferable that the glass part is disposed between the semiconductor substrate and the metal part and is also present on the surface of the metal part.

  At least a part of the void is an open pore as viewed from the copper-containing electrode surface side, and reaches the Sn-PO glass phase formed in the copper-containing electrode or on the semiconductor substrate side. There is also. In addition, it is thought that the performance (for example, volume resistivity) as an electrode and the power generation performance of a solar cell element are not reduced by including the void in the copper-containing electrode. At the time of heat and pressure treatment of the laminate obtained by laminating the copper-containing electrode, the connection material and the wiring member, the copper-containing electrode having this structure and the wiring member are thermocompression bonded with the connection material including the adhesive interposed therebetween. Thus, when the connection strength between the copper-containing electrode and the wiring member is improved by a so-called anchor effect in which at least a part of the connection material enters the gap and the copper-containing electrode and the wiring member are dynamically bonded to each other. Conceivable. As a result, it is considered that the reliability of the solar cell is improved and further stable power generation performance is exhibited. The portion where the copper-containing electrode and the wiring member are in contact may have a glass portion interposed between the copper-containing electrode and the wiring member, and the copper-containing electrode and the wiring member are in direct contact with each other. Also good.

On the other hand, when the connection between the copper-containing electrode and the wiring member is performed with solder or a conductive paste, the adhesion between the electrode and the wiring member is inferior to the case where the connection material is used. This is presumably because solder or conductive paste does not enter the gap formed in the copper-containing electrode as described above, and the anchor effect cannot be obtained.
Moreover, when the said composition for electrodes is not used, a space | gap part is hard to be formed in the electrode obtained after heat processing (baking), the said anchor effect becomes small, and there exists a possibility that the adhesiveness of an electrode and a wiring member may be inferior. .
Thus, the high adhesion between the electrode and the wiring member is first manifested by combining the electrode composition and the connection material included in the electrode connection set of the present invention.

  Further, in the present invention, by combining the electrode composition and the connection material, a reduction in electrical contact resistance can be achieved separately from the connection strength. This can be considered as follows, for example.

  As described above, the copper-containing electrode obtained from the electrode composition according to the present invention includes a void inside, and the connection material enters the void when the wiring member is thermocompression bonded. Here, a conductive layer including a metal part, a glass part, and a connection material is formed between the semiconductor substrate and the wiring member. At this time, the amount (volume) of the connection material entering the gap is increased as compared with an electrode having a small gap, for example, a conventional silver electrode, and as a result, a connection interposed between the electrode and the wiring member. The material thickness is significantly reduced. In addition, since the connection material is flow-excluded during the thermocompression bonding of the wiring member, the electrode and the wiring member are in direct contact with part of the conductive layer. As a result, the conductivity is improved and the electrical contact resistance between the electrode and the wiring member is reduced. In the portion where the electrode and the wiring member are in direct contact, the glass portion may be interposed between the metal portion and the wiring member, or the metal portion and the wiring member may be in direct contact. Furthermore, when the metal part and the wiring member are in direct contact, conductive components such as metal in the electrode and the wiring member are diffused from the contact part, so that the contact part is alloyed and the contact resistance is further reduced. This is also considered as one factor for improving the conductivity.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. .
In the present specification, “to” indicates a range including the numerical values described before and after the values as a minimum value and a maximum value, respectively.
Further, in the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. means.
In this specification, the term “layer” includes a configuration formed in a part in addition to a configuration formed in the entire surface when observed as a plan view.
In this specification, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.
The present invention will be described below.

[Electrode connection set]
The electrode connection set includes the electrode composition, the connection material, and other elements as necessary.
<Electrode composition>
The electrode composition includes phosphorus-tin-containing copper alloy particles and glass particles. A copper-containing electrode can be formed by applying this electrode composition to a semiconductor substrate having a pn junction and heat-treating (firing) it. In the present invention, a silicon substrate is described as an example of a semiconductor substrate having a pn junction, but the semiconductor substrate in the present invention is not limited to a silicon substrate.
Semiconductor substrates other than silicon substrates include gallium phosphide substrates, gallium nitride substrates, diamond substrates, aluminum nitride substrates, indium nitride substrates, gallium arsenide substrates, germanium substrates, zinc selenide substrates, zinc telluride substrates, cadmium telluride substrates. Examples include a substrate, a cadmium sulfide substrate, an indium phosphide substrate, a silicon carbide substrate, a germanium silicide substrate, and a copper indium selenium substrate.

  By using the electrode composition, oxidation of copper during heat treatment (firing) in the air is suppressed, and an electrode having a low resistivity can be formed. Furthermore, formation of a reactant phase between copper and the silicon substrate is suppressed, and a good ohmic contact can be formed between the formed electrode and the silicon substrate. This can be considered as follows, for example.

  First, when the electrode composition according to the present invention is heat-treated (fired), a Cu—Sn alloy phase and a Sn—PO glass phase are formed by the reaction between copper and tin in the phosphorus-tin-containing copper alloy particles. . By forming the Cu—Sn alloy phase, an electrode having a low volume resistivity (hereinafter also simply referred to as “resistivity”) can be formed. Here, since the Cu—Sn alloy phase is generated at a relatively low temperature of about 500 ° C., the electrode can be subjected to low-temperature heat treatment (firing), and the effect of reducing process costs can be expected.

This can be considered as follows, for example.
Copper and tin in the phosphorus-tin-containing copper alloy particles react with each other in a heat treatment (firing) step, and a Cu—Sn alloy phase as a metal part and a Sn—PO glass phase as a glass part. An electrode is formed. The Cu—Sn alloy phase forms a dense bulk metal portion between the Cu—Sn alloy phases. This bulk metal part is formed in the electrode and functions as a conductive layer, whereby an electrode having a low resistivity is formed. In addition, the dense bulk metal portion referred to here means a structure in which massive Cu—Sn alloy phases are in close contact with each other and are continuously formed in three dimensions.
On the other hand, the Sn—PO glass phase is formed between the Cu—Sn alloy phase and the silicon substrate. Thereby, it can be considered that adhesion of the Cu—Sn alloy phase to the silicon substrate can be obtained.

  It is preferable that the electrode composition further contains nickel-containing particles, or the phosphorus-tin-containing copper alloy particles further contain nickel. As a result, it is considered that the Cu—Sn alloy phase and nickel further react to form a Cu—Sn—Ni alloy phase. Since this Cu—Sn—Ni alloy phase is formed even at a relatively high temperature such as 800 ° C., an electrode having a low resistivity can be formed while maintaining oxidation resistance even in a heat treatment (firing) step at a higher temperature. Conceivable. In addition, by using a copper-containing electrode formed from an electrode composition containing the nickel-containing particles or an electrode composition containing phosphorus-tin-nickel-containing copper alloy particles, the electrode is maintained while maintaining adhesion to the silicon substrate. A better ohmic contact between the silicon substrate and the silicon substrate can be achieved. Similarly to the Cu—Sn alloy phase, the Cu—Sn—Ni alloy phase obtained by the electrode composition further containing nickel-containing particles or the phosphorus-tin-containing copper alloy particles further containing nickel is Cu— A dense bulk metal portion is formed between the Sn—Ni alloy phases and together with the Cu—Sn alloy phase. In addition, even if the Cu—Sn alloy phase and the Cu—Sn—Ni alloy phase are mixed in the electrode, it is considered that the function (for example, resistivity) is not lowered.

When copper particles imparted with oxidation resistance, which have been developed in the past, are used, the oxidation resistance is up to 300 ° C., and the copper particles are almost oxidized at a high temperature of 800 ° C. to 900 ° C. For this reason, it has not been put into practical use as an electrode for a solar cell element, and further, an additive applied for imparting oxidation resistance inhibits sintering of copper particles, resulting in a resistivity like silver. There is a problem that a low electrode cannot be obtained. As another technique for suppressing copper oxidation, there has been proposed a method through a special manufacturing process in which a conductive composition using copper as a conductive metal powder is heat-treated (fired) in an atmosphere such as nitrogen. . However, in this method, in order to suppress the oxidation of the copper particles, a sealed environment is required so as to have an atmosphere filled with nitrogen or the like, which is not suitable for mass production of solar cell elements in terms of manufacturing cost.
According to the present invention, an electrode having a low resistivity can be formed without using a special method.

In addition, since the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon, a good ohmic contact between the electrode formed by heat treatment (firing) and the silicon substrate can be obtained. It can be considered that it can be achieved. That is, the formation of a reactant phase (Cu ₃ Si) formed when a copper-containing electrode and silicon are directly contacted and heated is suppressed, and the silicon substrate is not deteriorated without deteriorating semiconductor performance (for example, pn junction characteristics). It is considered that a good ohmic contact can be expressed while maintaining the adhesiveness with.
Conventionally, ohmic contact with a silicon substrate has been cited as a problem for applying copper to an electrode of a solar cell element. The formation of Cu ₃ Si may extend to several μm from the interface of the silicon substrate, which may cause cracks on the silicon substrate side and cause performance deterioration of the solar cell element. In addition, the formed Cu ₃ Si lifts the copper-containing electrode, which may hinder the adhesion between the electrode and the silicon substrate, resulting in a decrease in the mechanical strength of the electrode.
According to the present invention, since the formation of the reactant phase (Cu ₃ Si) can be suppressed, good ohmic contact properties can be exhibited.

Hereinafter, each component contained in the composition for an electrode used in the present invention will be described in detail.
(Phosphorus particles containing phosphorus-tin)
The composition for electrodes concerning this invention contains at least 1 sort (s) of a phosphorus- tin containing copper alloy particle. Generally, as a copper alloy containing phosphorus, a brazing material called phosphorus copper brazing (phosphorus content: about 7% by mass or less) is known. Phosphorus copper brazing is also used as a bonding agent between copper and copper, but by using copper alloy particles containing phosphorus in the electrode composition according to the present invention, the reducibility of phosphorus to copper oxide is improved. It is possible to form an electrode having excellent oxidation resistance and low volume resistivity. Furthermore, the electrode can be subjected to low-temperature heat treatment (firing), and the process cost can be reduced.

  The phosphorus-tin-containing copper alloy particles in the present invention are particles composed of a copper alloy further containing tin in addition to phosphorus. By including the phosphorus-tin-containing copper alloy particles, an electrode including a Cu—Sn alloy phase that is a metal part and a Sn—P—O glass phase that is a glass part is formed in a heat treatment (firing) step.

  Specifically, by including phosphorus-tin-containing copper alloy particles, an electrode having excellent oxidation resistance and low resistivity utilizing the reducibility of phosphorus atoms in the phosphorus-tin-containing copper alloy particles to copper oxide Is formed. Moreover, a Cu-Sn alloy phase and a Sn-PO glass phase are formed with the resistivity kept low by the reaction between copper and tin in the phosphorus-tin-containing copper alloy particles. And, for example, the Sn—PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon, so that a reactant phase is formed between the copper-containing electrode and the silicon substrate. It can be considered that two characteristic mechanisms of suppressing and forming a good ohmic contact between the copper-containing electrode and the silicon substrate can be realized at once in a heat treatment (firing) step.

  When phosphorus-tin-containing copper alloy particles are used in the present invention, the phosphorus content contained in the phosphorus-tin-containing copper alloy is not particularly limited. From the viewpoint of oxidation resistance and resistivity, the phosphorus content is preferably 2% by mass or more and 15% by mass or less, more preferably 3% by mass or more and 12% by mass or less, and more preferably 4% by mass or more and 10% by mass. More preferably, it is as follows. When the phosphorus content contained in the phosphorus-tin-containing copper alloy is 15% by mass or less, a lower resistivity can be achieved, and the productivity of the phosphorus-tin-containing copper alloy particles tends to be excellent. Moreover, it exists in the tendency which can achieve more superior oxidation resistance because the phosphorus content rate contained in a phosphorus- tin containing copper alloy is 2 mass% or more.

  Moreover, the tin content contained in the phosphorus-tin-containing copper alloy when using the phosphorus-tin-containing copper alloy particles in the present invention is not particularly limited. From the viewpoint of oxidation resistance and reactivity with copper and phosphorus, it is preferably 5% by mass or more and 30% by mass or less, more preferably 6% by mass or more and 25% by mass or less, and 7% by mass or more and 20% by mass. % Or less is more preferable. When the tin content contained in the phosphorus-tin-containing copper alloy is 30% by mass or less, a sufficient volume of the Cu—Sn alloy phase can be formed, and the resistivity of the electrode tends to decrease. Moreover, it exists in the tendency which can produce reaction with copper and phosphorus more uniformly by making content rate of tin into 5 mass% or more.

  Furthermore, as a combination of phosphorus content and tin content contained in the phosphorus-tin-containing copper alloy when using phosphorus-tin-containing copper alloy particles in the present invention, oxidation resistance, resistivity, and reactivity with copper and phosphorus From this point of view, the phosphorus content is preferably 2% by mass or more and 15% by mass or less, and the tin content is preferably 5% by mass or more and 30% by mass or less, and the phosphorus content is 3% by mass or more and 12% by mass or less. More preferably, the tin content is 6% by mass or more and 25% by mass or less, the phosphorus content is 4% by mass or more and 10% by mass or less, and the tin content is 7% by mass or more and 20% by mass. More preferably, it is as follows.

The phosphorus-tin-containing copper alloy in the present invention is also preferably a copper alloy further containing a specific metal atom which is at least one selected from the group consisting of silver, manganese and cobalt in addition to phosphorus and tin. By further including the specific metal atom, a lower resistance electrode tends to be formed.
The content rate of the specific metal atom in the copper alloy containing phosphorus, tin, and the specific metal atom can be appropriately selected according to the type and purpose of the specific metal atom. The content of the specific metal atom can be, for example, 0.05% by mass to 20% by mass, preferably 0.1% by mass to 15% by mass, and 1% by mass to 10% by mass. Is more preferable. When the content of the specific metal atom is 0.05% by mass or more, the melting point of the alloy particles can be further lowered, and the sintering reaction of the alloy particles in the heat treatment (firing) step tends to further progress. Further, when the content of the specific metal atom is 20% by mass or less, the oxidation resistance is improved and an electrode having a low resistivity tends to be formed.

The phosphorus-tin-containing copper alloy is a copper alloy containing phosphorus and tin, but may further contain other atoms inevitably mixed other than silver, manganese and cobalt. Other atoms that are inevitably mixed include, for example, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, Zr, W, and Mo. Ti, Ni and Au can be mentioned.
Further, the content of other atoms inevitably mixed in the phosphorus-tin-containing copper alloy particles can be, for example, 3% by mass or less in the phosphorus-tin-containing copper alloy particles, and is resistant to oxidation. From the viewpoints of properties and resistivity, it is preferably 1% by mass or less.

In the present invention, the phosphorus-tin-containing copper alloy particles may be used singly or in combination of two or more.
In the present invention, “using two or more types of phosphorus-tin-containing copper alloy particles in combination” means two or more types of phosphorus-tin having the same particle shape such as the particle size and particle size distribution described later, although the component ratio is different. When using in combination with contained copper alloy particles, when using a combination of two or more types of phosphorus-tin containing copper alloy particles having the same component ratio but different particle shapes, two or more types having different component ratios and particle shapes. The case where it uses combining a phosphorus- tin containing copper alloy particle etc. is mentioned.

The particle diameter of the phosphorus-tin-containing copper alloy particles is not particularly limited, but the particle diameter (D50%) when the integrated volume is 50% is preferably 0.4 μm to 10 μm, preferably 1 μm to 7 μm. It is more preferable that By setting D50% of the phosphorus-tin-containing copper alloy particles to 0.4 μm or more, the oxidation resistance tends to be more effectively improved. Moreover, the contact area of the phosphorus-tin containing copper alloy particle | grains in an electrode becomes large because D50% of a phosphorus- tin containing copper alloy particle shall be 10 micrometers or less, and it exists in the tendency for a resistivity to fall more effectively. The particle size (D50%) of the phosphorus-tin-containing copper alloy particles is measured by a laser diffraction particle size distribution analyzer (for example, Beckman Coulter, Inc., LS 13 320 type laser scattering diffraction particle size distribution analyzer). The Specifically, phosphorus-tin-containing copper alloy particles are added to 125 g of a solvent (terpineol) within a range of 0.01% by mass to 0.3% by mass to prepare a dispersion. About 100 ml of this dispersion is poured into a cell and measured at 25 ° C. The particle size distribution is measured as a solvent refractive index of 1.48.
Moreover, there is no restriction | limiting in particular as a shape of the said phosphorus- tin containing copper alloy particle, Any of substantially spherical shape, flat shape, block shape, plate shape, scale shape, etc. may be sufficient from a viewpoint of oxidation resistance and a resistivity. It is preferably substantially spherical, flat or plate-like.

The phosphorus-tin-containing copper alloy can be produced by a commonly used method. In addition, the phosphorus-tin-containing copper alloy particles should be prepared using a normal method of preparing metal powder using a phosphorus-tin-containing copper alloy prepared to have a desired phosphorus content and tin content. Can do. For example, it can be manufactured by a conventional method using a water atomizing method. For details of the water atomization method, the description of Metal Handbook (Maruzen Co., Ltd. Publishing Division) can be referred to.
Specifically, a phosphorus-tin-containing copper alloy particle is produced by dissolving and pulverizing the phosphorus-tin-containing copper alloy by nozzle spraying, and then drying and classifying the obtained powder. be able to. Moreover, the phosphorus-tin containing copper alloy particle | grains which have a desired particle diameter can be manufactured by selecting classification conditions suitably.

(Phosphorus-tin-nickel-containing copper alloy particles)
In the electrode composition according to the present invention, the phosphorus-tin-containing copper alloy particles may further contain nickel, whereby the phosphorus-tin-containing copper alloy particles may be used as the phosphorus-tin-nickel-containing copper alloy particles. The phosphorus-tin-nickel-containing copper alloy particles are copper alloy particles that further contain tin and nickel in addition to phosphorus. By using phosphorus-tin-nickel-containing copper alloy particles, oxidation resistance at higher temperatures can be expressed in the heat treatment (firing) step. That is, by using phosphorus-tin-nickel-containing copper alloy particles, the electrode composition can be heat-treated (fired) at a higher temperature.

  Specifically, the composition for an electrode of the present invention contains phosphorus-tin-nickel-containing copper alloy particles as metal particles. An electrode having excellent oxidation resistance and low resistivity is formed by utilizing reducibility. In addition, by including tin and nickel, a Cu—Sn alloy phase, or a Cu—Sn—Ni alloy phase and a Sn—P—O glass phase are formed while keeping the resistivity low. For example, the Sn—P—O glass phase is formed in a three-dimensional continuous structure of a Cu—Sn alloy phase or a Cu—Sn—Ni alloy phase, thereby making the electrode itself a dense structure, resulting in an electrode An improvement in strength is obtained. Moreover, a favorable ohmic contact is formed between a copper containing electrode and a silicon substrate because the Sn-PO glass phase functions as a barrier layer for preventing mutual diffusion between copper and silicon. It can be considered that such a characteristic mechanism can be realized collectively in the heat treatment (firing) step.

  The phosphorus content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles in the present invention is not particularly limited. From the viewpoint of oxidation resistance (resistivity) and ability to form a Sn—PO glass phase, the phosphorus content is preferably 2.0% by mass to 15.0% by mass, and 2.5% by mass to 12%. It is more preferably 0.0% by mass, and even more preferably 3.0% by mass to 10.0% by mass. When the phosphorus content contained in the phosphorus-tin-nickel-containing copper alloy is 15.0% by mass or less, a lower resistivity can be achieved, and the productivity of the phosphorus-tin-nickel-containing copper alloy particles can be increased. It tends to be excellent. Moreover, by setting it as 2.0 mass% or more, it exists in the tendency which can form an Sn-PO glass phase effectively and can form the electrode excellent in the adhesiveness and ohmic contact with respect to a semiconductor substrate.

  Moreover, the tin content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited. From the viewpoints of oxidation resistance, reactivity with copper and nickel, and the ability to form a Sn—PO glass phase, the tin content is preferably 3.0% by mass to 30.0% by mass, and 4.0. It is more preferable that it is mass%-25.0 mass%, and it is still more preferable that it is 5.0 mass%-20.0 mass%. It exists in the tendency which can form a Cu-Sn-Ni alloy phase with a low resistivity because the tin content rate contained in a phosphorus- tin- nickel containing copper alloy is 30.0 mass% or less. Moreover, the reactivity with copper and nickel, and the reactivity with phosphorus improve by making tin content into 3.0 mass% or more, respectively, and a Cu-Sn-Ni alloy phase and a Sn-PO glass phase respectively. Tends to be formed effectively.

  Moreover, the nickel content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited. From the viewpoint of oxidation resistance, it is preferably 3.0% by mass to 30.0% by mass, more preferably 3.5% by mass to 25.0% by mass, and 4.0% by mass to 20%. More preferably, it is 0 mass%. When the nickel content in the phosphorus-tin-nickel-containing copper alloy is 30.0% by mass or less, a low resistivity Cu-Sn-Ni alloy phase tends to be formed effectively. Moreover, it exists in the tendency which can improve the oxidation resistance in a high temperature area | region especially 500 degreeC or more by making nickel content rate 3.0 mass% or more.

  Furthermore, as a combination of phosphorus content, tin content, and nickel content contained in the phosphorus-tin-nickel-containing copper alloy constituting the phosphorus-tin-nickel-containing copper alloy particles, oxidation resistance, volume resistance of the electrode The phosphorus content is 2.0% by mass to 15.0% by mass from the viewpoint of the rate, the reactivity with copper and phosphorus, the ability to form a Sn—PO glass phase, and the adhesion between the electrode and the silicon substrate. The tin content is preferably 3.0% by mass to 30.0% by mass, the nickel content is preferably 3.0% by mass to 30.0% by mass, and the phosphorus content is 2%. 0.5% by mass to 12.0% by mass, and the tin content is 4.0% by mass to 25.0% by mass, and the nickel content is 3.5% by mass to 25.0% by mass. It is more preferable that the phosphorus content is 3.0% by mass to 10.0% by mass. Te, and a tin content of 5.0 wt% to 20.0 wt%, and nickel content is more preferably 4.0 wt% to 20.0 wt%.

The phosphorus-tin-nickel-containing copper alloy particles are copper alloy particles containing phosphorus, tin, and nickel, but may further contain other atoms inevitably mixed. Examples of other atoms inevitably mixed include Ag, Mn, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, and Zr. , W, Mo, Ti, Co, Au and Bi.
The content of other atoms inevitably mixed in the phosphorus-tin-nickel-containing copper alloy particles can be, for example, 3% by mass or less in the phosphorus-tin-nickel-containing copper alloy particles, and is resistant to oxidation. From the viewpoints of performance and low resistivity, it is preferably 1% by mass or less.

  Phosphorus-tin-nickel-containing copper alloy particles may be used singly or in combination of two or more. In the present invention, “use in combination of two or more types of phosphorus-tin-nickel-containing copper alloy particles” means that two or more types of phosphorus having the same particle shape such as the particle size and particle size distribution described later, although the component ratios are different. -When using tin-nickel-containing copper alloy particles in combination, the component ratio is the same, but when two or more types of phosphorus-tin-nickel-containing copper alloy particles having different particle shapes are used in combination, the component ratio and particle shape are A case where two or more kinds of phosphorus-tin-nickel-containing copper alloy particles different from each other are used in combination.

  There is no restriction | limiting in particular as a particle diameter of a phosphorus- tin- nickel containing copper alloy particle. In the particle size distribution, the particle diameter (D50%) when the volume integrated from the small diameter side is 50% is preferably 0.4 μm to 10 μm, and more preferably 1 μm to 7 μm. By setting D50% of the phosphorus-tin-nickel-containing copper alloy particles to 0.4 μm or more, the oxidation resistance tends to be more effectively improved. By making D50% of the phosphorus-tin-nickel-containing copper alloy particles 10 μm or less, the contact area between the phosphorus-tin-nickel-containing copper alloy particles in the electrode is increased, and the resistivity of the electrode is more effectively reduced. Tend to.

  The particle diameter of the phosphorus-tin-nickel-containing copper alloy particles is the same as the method for measuring the particle diameter of the phosphorus-tin-containing copper alloy particles.

  The shape of the phosphorus-tin-nickel-containing copper alloy particles is not particularly limited, and may be any of a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like. From the viewpoint of oxidation resistance and low resistivity, the shape of the phosphorus-tin-nickel-containing copper alloy particles is preferably substantially spherical, flat or plate-like.

  The phosphorus-tin-nickel-containing copper alloy can be produced by a commonly used method, and the phosphorus-tin-nickel-containing copper alloy particles have a desired phosphorus content, tin content, and nickel content. Using the phosphorus-tin-nickel-containing copper alloy thus prepared, it can be produced in the same manner as the phosphorus-tin-containing copper alloy particles.

(Nickel-containing particles)
When the composition for electrodes used in the present invention contains phosphorus-tin-containing copper alloy particles, it is preferable to further contain nickel-containing particles as metal particles. By including nickel-containing particles in addition to the phosphorus-tin-containing copper alloy particles, oxidation resistance at higher temperatures tends to be exhibited in the heat treatment (firing) step. That is, by including nickel-containing particles, the electrode composition tends to be heat-treated (fired) at a higher temperature. In addition, when the composition for electrodes used by this invention contains nickel containing particle | grains, you may use together with phosphorus- tin containing copper alloy particle | grains, and may use together with phosphorus- tin- nickel containing copper alloy particle | grains. . Moreover, when the composition for electrodes used by this invention contains a phosphorus- tin- nickel containing copper alloy particle | grain, it is not necessary to use together with a nickel containing particle | grain.

The nickel-containing particles are not particularly limited as long as the particles contain nickel. Among these, at least one selected from nickel particles and nickel alloy particles is preferable, and at least one selected from nickel particles and nickel alloy particles having a nickel content of 1% by mass or more is preferable.
The purity of nickel in the nickel particles is not particularly limited. For example, the purity of the nickel particles can be 95% by mass or more, preferably 97% by mass or more, and more preferably 99% by mass or more.

  Further, the type of alloy is not limited as long as the nickel alloy particles are alloy particles containing nickel. Among these, from the viewpoint of the melting point of the nickel alloy particles and the reactivity with the Cu—Sn alloy phase, the nickel content is preferably 1% by mass or more, and the nickel content is 3% by mass or more. More preferably, it is a nickel alloy particle, more preferably a nickel alloy particle having a nickel content of 5% by mass or more, and a nickel alloy particle having a nickel content of 10% by mass or more. Particularly preferred. There is no particular limitation on the upper limit of the nickel content.

Examples of the nickel alloy constituting the nickel alloy particles include a Ni—Fe alloy, a Ni—Cu alloy, a Ni—Cu—Zn alloy, a Ni—Cr alloy, and a Ni—Cr—Ag alloy. In particular, nickel alloy particles containing Ni-58Fe, Ni-75Cu, Ni-6Cu-20Zn, etc. can react more uniformly with phosphorus-tin-containing copper alloy particles or phosphorus-tin-nickel-containing copper alloy particles. Therefore, it can be suitably used. For example, in the case of Ni-AX-BY-CZ, the nickel alloy includes A mass% of element X, B mass% of element Y, and C mass% of element Z in the nickel alloy. It shows that.
In the electrode composition, these nickel-containing particles may be used alone or in combination of two or more.
In the present invention, “use in combination of two or more kinds of nickel-containing particles” means that two or more kinds of nickel-containing particles having the same particle shape such as particle diameter and particle size distribution described later are used in combination although the component ratio is different. In this case, there are cases where two or more kinds of nickel-containing particles having the same component ratio but different particle shapes are used in combination, and two or more kinds of nickel-containing particles having different component ratios and particle shapes are used in combination. .

The nickel-containing particles may further contain other atoms inevitably mixed. Examples of other atoms inevitably mixed include Ag, Mn, Sb, Si, K, Na, Li, Ba, Sr, Ca, Mg, Be, Zn, Pb, Cd, Tl, V, Al, and Zr. , W, Mo, Ti, Co, Sn, and Au.
Moreover, the content rate of other atoms inevitably mixed in the nickel-containing particles can be, for example, 3% by mass or less in the nickel-containing particles, and the melting point and phosphorus-tin-containing copper alloy particles or From the viewpoint of reactivity with the phosphorus-tin-nickel-containing copper alloy particles, the content is preferably 1% by mass or less.

Although there is no restriction | limiting in particular as a particle diameter of the said nickel containing particle | grain, As D50%, it is preferable that they are 0.5 micrometer-20 micrometers, it is more preferable that they are 1 micrometer-15 micrometers, and it is still more preferable that they are 3 micrometers-15 micrometers. When the particle diameter of the nickel-containing particles is 0.5 μm or more, the oxidation resistance of the nickel-containing particles themselves tends to be improved. Further, when the particle diameter of the nickel-containing particles is 20 μm or less, the contact area with the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles increases, and the phosphorus-tin-containing copper alloy particles or phosphorus -Reaction with tin-nickel-containing copper alloy particles tends to proceed effectively.
In addition, the measuring method of the particle diameter (D50%) of nickel containing particle | grains is the same as the measuring method of the particle diameter of phosphorus- tin containing copper alloy particle | grains.
Further, the shape of the nickel-containing particles is not particularly limited, and may be any of a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, etc., but from the viewpoint of oxidation resistance and resistivity, a substantially spherical shape. The shape is preferably flat or plate-like.

Moreover, the content rate of the nickel containing particle in the case where the composition for electrodes contains nickel containing particle is not particularly limited. Among these, the content of the nickel-containing particles is 10% by mass or more and 70% when the total content of the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles and the nickel-containing particles is 100% by mass. It is preferably at most mass%, more preferably at least 12 mass% and at most 55 mass%, further preferably at least 15 mass% and at most 50 mass%, and at least 15 mass% and at most 35 mass%. Is particularly preferred.
By setting the content rate of the nickel-containing particles to 10% by mass or more, the Cu-Sn-Ni alloy phase tends to be formed more uniformly. In addition, by setting the content of the nickel-containing particles to 70% by mass or less, a sufficient volume of the Cu—Sn—Ni alloy phase can be formed, and the resistivity of the electrode tends to be further reduced.

  From the viewpoint of oxidation resistance and electrode resistivity in the electrode composition, phosphorus-tin-containing copper alloy particles (or phosphorus-tin-nickel-containing copper alloy particles) and nickel-containing particles added as necessary The total content is preferably 60% by mass or more and 94% by mass or less, and more preferably 64% by mass or more and 88% by mass or less.

(Glass particles)
The composition for electrodes used in the present invention contains glass particles. When the electrode composition contains glass particles, adhesion between the electrode and the silicon substrate is improved during heat treatment (firing). Further, particularly in the formation of the electrode on the light-receiving surface side of the solar cell, the silicon nitride layer as the antireflection layer is removed by so-called fire-through during heat treatment (firing), and an ohmic contact between the electrode and the silicon substrate is formed.

  The glass particles are preferably glass particles containing glass having a softening temperature of 650 ° C. or lower and a crystallization start temperature exceeding 650 ° C. from the viewpoint of adhesion to a silicon substrate and electrode resistivity. In addition, the said softening temperature and the said crystallization start temperature are measured by a normal method using a differential thermal-thermogravimetric analyzer (TG-DTA).

  When the electrode composition is used as an electrode on the solar cell light-receiving surface side, the glass particles soften and melt at the electrode formation temperature, oxidize the contacted silicon nitride layer, and take in oxidized silicon dioxide. As long as the antireflection layer can be removed, glass particles usually used in the technical field can be used without particular limitation.

In general, the glass particles contained in the electrode composition are preferably composed of glass containing lead from the viewpoint that silicon dioxide can be efficiently incorporated. Examples of such glass containing lead include those described in Japanese Patent No. 3050064, and these can also be preferably used in the present invention.
In the present invention, it is preferable to use lead-free glass that does not substantially contain lead in consideration of the influence on the environment. Examples of the lead-free glass include the lead-free glass described in paragraphs 0024 to 0025 of JP-A-2006-313744 and the lead-free glass described in JP-A-2009-188281. It is also preferable to select an appropriate material from free glass and apply it to the electrode composition used in the present invention.

  Moreover, when using the said composition for electrodes as a back surface output extraction electrode other than the electrode by the side of a solar cell light-receiving surface side, the glass particle containing the glass whose softening temperature is 650 degrees C or less and whose crystallization start temperature exceeds 650 degreeC If it is, it can be used without including a component necessary for fire-through such as lead.

Examples of the glass component constituting the glass particles used in the electrode composition include silicon oxide (SiO or SiO ₂ ), phosphorus oxide (P ₂ O ₅ ), aluminum oxide (Al ₂ O ₃ ), boron oxide ( B ₂ O _3), vanadium oxide _{(V 2 O} 5), potassium oxide _(K 2 O), bismuth oxide _{(Bi 2 O} 3), sodium oxide _(Na 2 O), lithium oxide _(Li 2 O), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO), beryllium oxide (BeO), zinc oxide (ZnO), lead oxide (PbO), cadmium oxide (CdO), tin oxide (SnO) ), Zirconium oxide (ZrO ₂ ), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), lanthanum oxide (La ₂ O ₃ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), yttrium oxide (Y ₂ O ₃ ), titanium oxide (TiO ₂ ), germanium oxide (GeO ₂ ), tellurium oxide (TeO) ₂ ), lutetium oxide (Lu ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ ), copper oxide (CuO), iron oxide (FeO, Fe ₂ O ₃ or Fe ₃ O ₄ ), silver oxide (AgO or Ag ₂₎ O) and manganese oxide (MnO).

Among them, glass particles containing at least one selected from the group consisting of SiO ₂ , P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , V ₂ O ₅ , Bi ₂ O ₃ , ZnO and PbO are used. It is more preferable to use glass particles containing at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ and PbO. In the case of such glass particles, the softening temperature tends to decrease more effectively. Furthermore, since the wettability with the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles and the nickel-containing particles added as necessary is improved, between the particles in the heat treatment (firing) process Sintering progresses and it tends to be possible to form an electrode with a lower resistivity.

On the other hand, from the viewpoint of reducing the contact resistivity, glass particles containing phosphorus oxide (phosphoric acid glass particles, P ₂ O ₅ glass particles, etc.) are preferable, and glass particles further containing vanadium oxide in addition to phosphorus oxide. (P ₂ O ₅ —V ₂ O ₅ glass particles) is more preferable. By further containing vanadium oxide, the oxidation resistance is further improved, and the resistivity of the electrode tends to be further reduced. This can be attributed to, for example, that the softening temperature of the glass is lowered by further containing vanadium oxide. When using phosphorus oxide-vanadium oxide glass particles (P ₂ O ₅ —V ₂ O ₅ glass particles), the vanadium oxide content is preferably 1% by mass or more based on the total mass of the glass. It is more preferable that it is% -70 mass%.

Although there is no restriction | limiting in particular as a particle diameter of the glass particle in the composition for electrodes used by this invention, The particle diameter (D50%) in case an integrated volume is 50% is 0.5 micrometer or more and 10 micrometers or less. It is preferably 0.8 μm or more and 8 μm or less. When the particle diameter of the glass particles is 0.5 μm or more, the workability during the production of the electrode composition tends to be improved. Moreover, since the particle diameter of the glass particles is 10 μm or less, the glass particles can be more uniformly dispersed in the electrode composition, and fire-through can be efficiently generated in the heat treatment (firing) step, and the adhesion to the silicon substrate is also improved. It tends to improve. In addition, the measuring method of the particle diameter (D50%) of a glass particle is the same as the measuring method of the particle diameter of a phosphorus- tin containing copper alloy particle.
Moreover, there is no restriction | limiting in particular as a shape of the said glass particle, Any of substantially spherical shape, flat shape, block shape, plate shape, scale shape, etc. may be sufficient. From the viewpoint of oxidation resistance and resistivity, it is preferably substantially spherical, flat or plate-like.

  The content of the glass particles is preferably 0.1% by mass to 12% by mass, more preferably 0.5% by mass to 10% by mass, based on the total mass of the electrode composition. It is still more preferable that it is% -9 mass%. By including glass particles with a content in such a range, oxidation resistance, lower electrode resistivity, and lower contact resistance can be achieved more effectively, and the reaction between the metal particles can be promoted. There is a tendency.

  In the electrode composition, the ratio (mass ratio) of the glass particle content to the total metal particle content is preferably 0.01 to 0.18, and preferably 0.03 to 0.15. More preferred. Inclusion of glass particles in such a content ratio tends to more effectively achieve oxidation resistance, lower electrode resistivity and lower contact resistance, and promote the reaction between the metal particles. It is in.

(Dispersion medium)
The electrode composition used in the present invention may contain a dispersion medium. Thereby, the liquid physical properties (for example, viscosity and surface tension) of the electrode composition can be adjusted to the liquid physical properties required depending on the application method when applying to a semiconductor substrate or the like.
Examples of the dispersion medium include at least one of a solvent and a resin.

  The solvent is not particularly limited, and is a hydrocarbon solvent such as hexane, cyclohexane or toluene, a halogenated hydrocarbon solvent such as dichloroethylene, dichloroethane or dichlorobenzene, tetrahydrofuran, furan, tetrahydropyran, pyran, dioxane, or 1,3-dioxolane. , Cyclic ether solvents such as trioxane, amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone and cyclohexanone, ethanol Alcohol solvents such as 2-propanol, 1-butanol and diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoacetate, 2,2,4-to Methyl-1,3-pentanediol monopropionate, 2,2,4-trimethyl-1,3-pentanediol monobutyrate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Ester solvents of polyhydric alcohols such as 2,2,4-triethyl-1,3-pentanediol monoacetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, polyhydric alcohols such as butyl cellosolve, diethylene glycol monobutyl ether, diethylene glycol diethyl ether Ether solvent, terpinene such as α-terpinene, terpineol such as α-terpineol, pinene such as α-pinene and β-pinene, myrcene, alloocimene, limonene, dipentene, carvone, Examples thereof include terpene solvents such as men and ferrandrene, and mixtures thereof.

The solvent is a group consisting of a polyhydric alcohol ester solvent, a terpene solvent, and a polyhydric alcohol ether solvent from the viewpoint of imparting properties (coatability or printability) when forming the electrode composition on a semiconductor substrate. It is preferably at least one selected from the group consisting of polyhydric alcohol ester solvents and terpene solvents, and more preferably at least one selected from the group consisting of terpene solvents.
In the electrode composition used in the present invention, the solvent may be used alone or in combination of two or more.

  Further, as the resin, any resin that is usually used in the technical field can be used without particular limitation as long as it can be thermally decomposed by heat treatment (firing) treatment. There may be. Specifically, cellulose resins such as methylcellulose, ethylcellulose, carboxymethylcellulose, nitrocellulose, polyvinyl alcohol resins, polyvinylpyrrolidone resins, acrylic resins, vinyl acetate-acrylic acid ester copolymers, butyral resins such as polyvinyl butyral, phenol-modified alkyds, etc. Examples thereof include resins, alkyd resins such as castor oil fatty acid-modified alkyd resins, epoxy resins, phenol resins, rosin ester resins and the like.

In the present invention, when the resin is contained in the electrode composition, it is preferably at least one selected from the group consisting of a cellulose resin and an acrylic resin from the viewpoint of disappearance in the heat treatment (firing) treatment.
In the present invention, the resins may be used alone or in combination of two or more.

  In the present invention, the weight average molecular weight of the resin when the resin is contained in the electrode composition is not particularly limited. Among them, the weight average molecular weight is preferably from 5,000 to 500,000, and more preferably from 10,000 to 300,000. It exists in the tendency which can suppress that the viscosity of the composition for electrodes increases that the weight average molecular weight of the said resin is 5000 or more. If the weight average molecular weight of the resin is 5000 or more, it is considered that the particles can hardly aggregate each other due to the steric repulsion when adsorbed to the metal particles in the electrode composition. On the other hand, when the weight average molecular weight of the resin is 500,000 or less, aggregation of the resins in the solvent is suppressed and the viscosity of the electrode composition tends to be suppressed from increasing. In addition, when the weight average molecular weight of the resin is 500,000 or less, it is suppressed that the resin combustion temperature becomes high, and the resin is not combusted and remains as a foreign substance when the electrode composition is heat-treated (fired). Therefore, it is likely that an electrode having a lower resistivity can be formed.

In the present invention, when the dispersion medium contains the dispersion medium, the content of the dispersion medium can be appropriately selected according to the desired liquid properties and the type of the dispersion medium to be used. For example, the content of the dispersion medium is preferably 3% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 35% by mass or less, based on the total mass of the electrode composition, and 7% by mass. More preferably, it is 30 mass% or less.
When the content of the dispersion medium is within the above range, the application suitability when applying the composition for an electrode to a semiconductor substrate is improved, and an electrode having a desired width and height can be more easily formed. It tends to be possible.
The types of the solvent and the resin in the dispersion medium and the content ratio in the dispersion medium can be appropriately selected in consideration of the method for applying the electrode composition.

(flux)
The electrode composition may contain a flux. The oxide film formed on the surface of the phosphorus-tin-containing copper alloy particles or phosphorus-tin-nickel-containing copper alloy particles by including the flux is removed, and the phosphorus-tin-containing copper alloy particles or phosphorus- during the heat treatment (firing) The reduction reaction of the tin-nickel-containing copper alloy particles can be promoted. Furthermore, the effect that the adhesiveness of an electrode and a silicon substrate improves is also acquired.

  The flux can remove the oxide film formed on the surface of phosphorus-tin-containing copper alloy particles or phosphorus-tin-nickel-containing copper alloy particles, and promote melting of nickel-containing particles added as necessary If there is no restriction in particular. Specifically, fatty acids, boric acid compounds, fluorinated compounds, and borofluorinated compounds can be mentioned as preferred fluxes.

More specifically, the flux includes lauric acid, myristic acid, palmitic acid, stearic acid, sorbic acid, stearic acid, propionic acid, boron oxide, potassium borate, sodium borate, lithium borate, potassium borofluoride, borofluoride. Sodium fluoride, lithium borofluoride, acidic potassium fluoride, acidic sodium fluoride, acidic lithium fluoride, potassium fluoride, sodium fluoride, lithium fluoride and the like can be mentioned.
In particular, the heat resistance during electrode heat treatment (firing) (the property that the flux does not volatilize at low temperatures during heat treatment (firing)) and the oxidation resistance of phosphorus-tin-containing copper alloy particles or phosphorus-tin-nickel-containing copper alloy particles are complemented. From the viewpoint, potassium borate and potassium borofluoride are particularly preferable fluxes.
In the electrode composition used in the present invention, each of these fluxes may be used alone or in combination of two or more.

  In the electrode composition, the flux content in the case of containing the flux effectively expresses the oxidation resistance of the phosphorus-tin-containing copper alloy particles or the phosphorus-tin-nickel-containing copper alloy particles, From the viewpoint of reducing the porosity of the part from which the flux has been removed when the heat treatment (firing) is completed, the total mass of the electrode composition is preferably 0.1% by mass to 5% by mass, and 0.3% by mass It is more preferable that it is -4 mass%, It is still more preferable that it is 0.5 mass%-3.5 mass%, It is especially preferable that it is 0.7 mass%-3 mass%, 1 mass%-2 It is very preferable that the content be 5% by mass.

(Other ingredients)
The electrode composition used in the present invention can further contain other components that are usually used in the technical field, if necessary, in addition to the components described above. Examples of other components include plasticizers, dispersants, surfactants, inorganic binders, metal oxides, ceramics, and organometallic compounds.

There is no restriction | limiting in particular as a manufacturing method of the composition for electrodes used by this invention. It can manufacture by disperse | distributing or mixing the said metal particle, glass particles, and other components, such as a dispersion medium added as needed, using the dispersion method or mixing method used normally.
The dispersion method and the mixing method are not particularly limited, and can be appropriately selected and applied from commonly used dispersion methods and mixing methods.

<Connection material>
The connection material in the present invention includes an adhesive.
As long as the connection material includes an adhesive capable of connecting an electrode formed from the electrode composition and a wiring member to be described later in the manufacturing process of the solar cell, the shape, material, component, etc. There is no particular limitation. Examples of the state of the connecting material include a film form, a paste form, and a solution form. About the state of the said connection material, it can adjust suitably with the kind and content rate of the component contained in a connection material. From the viewpoints of solar cell production efficiency, handleability, power generation performance stability, and the like, the connecting material is preferably in the form of a film.

From the viewpoint of forming a film-like connection material, the connection material preferably includes an adhesive, a curing agent, and a film-forming material.
As such a connection material, for example, a conductive adhesive film described in JP-A-2007-214533 can be exemplified, and these can be suitably used in the present invention. By using such a connection material, it is possible to provide a solar cell and a solar cell module that exhibit stable power generation performance. This can be considered as follows, for example.

When the electrode of the solar cell element and the wiring member are connected using the conductive adhesive film, it is possible to connect in a low temperature region around 200 ° C. Therefore, even when a thin solar cell element is used, the wiring Generation | occurrence | production of the curvature or crack in the case of a connection with a member can be suppressed. In addition, since solder does not ooze out during solder connection, the light receiving area of the solar cell element can be increased, and as a result, improvement in power generation performance can be expected.
By using the connection material, it is possible to expect effects such as improvement in power generation performance as described above.

  In addition, the electroconductive adhesive film described in JP 2007-214533 A and the like includes electroconductive particles, and can exhibit electrical conductivity between the substrates through the electroconductive particles during thermocompression bonding. The connection material used in the present invention is not limited to this composition, and may not contain the conductive particles. That is, when the connection material does not contain conductive particles, the copper-containing electrode and the wiring member can obtain conductivity by directly contacting the connection material at a portion where the connection material is flow-excluded by pressurization.

It is preferable that the connection material has a viscosity of 40000 Pa · s or less under conditions of thermocompression bonding of the wiring member. When the viscosity is 40000 Pa · s or less, the wiring member tends to be more easily penetrated into the void formed in the electrode during thermocompression bonding. The viscosity of the connecting material is preferably 20000 Pa · s or less, and more preferably 15000 Pa · s or less. In addition, it is preferable that the viscosity of a connection material is 5000 Pa * s or more at the point of the handling in the manufacturing process of a solar cell.
The viscosity of the connecting material can be confirmed under the conditions of 25 ° C. and a frequency of 10 Hz using a TA Instruments Japan Co., Ltd. and a shear viscometer measuring device (ARES).
Hereinafter, each component will be described.

(adhesive)
The adhesive preferably exhibits insulating properties. The adhesive exhibiting insulating properties is not particularly limited, but it is preferable to use a thermosetting resin from the viewpoint of adhesion reliability.
A well-known thing can be used as a thermosetting resin, For example, an epoxy resin, a phenol resin, a melamine resin, and an alkyd resin are mentioned. Among these, an epoxy resin is preferable from the viewpoint of obtaining sufficient connection reliability.

  The content of the adhesive is not particularly limited. From the viewpoint of film formability before curing or adhesive strength after curing, it is preferably 20% by mass or more and 70% by mass or less in the connection material, more preferably 30% by mass or more and 60% by mass or less, More preferably, it is at least 50% by mass.

(Curing agent)
Examples of the curing agent that can be contained in the connecting material include an anion polymerizable catalyst type curing agent, a cationic polymerizable catalyst type curing agent, and a polyaddition type curing agent. These may be used alone or in combination of two or more. Of these, anionic or cationic polymerizable catalyst-type curing agents are preferred because they are excellent in rapid curability and do not require chemical equivalent considerations.

Examples of the anionic or cationic polymerizable catalyst-type curing agent include tertiary amine derivatives, imidazole derivatives, hydrazide compounds, boron trifluoride-amine complexes, onium salts (sulfonium salts, ammonium salts, etc.) amine imides, diamino maleonitriles. , Melamine and its derivatives, salts of polyamines, and dicyandiamide, and these modifications can also be used. Examples of the polyaddition type curing agent include polyamines, polymercaptans, polyphenols, and acid anhydrides.
As the anionic or cationic polymerizable catalyst-type curing agent, specifically, a tertiary amine derivative or an imidazole derivative is preferably used in terms of adhesive strength, and an imidazole derivative is more preferably used.

As the curing agent, a latent curing agent is preferred because the active point of reaction initiation by thermocompression bonding is relatively clear and suitable for a connection method involving a thermocompression bonding process. Here, the latent curing agent is a substance that exhibits a curing function under certain specific conditions (such as temperature). Examples of the latent curing agent include those obtained by protecting a normal curing agent with microcapsules and the like, and those having a structure in which a curing agent and various compounds form a salt.
In such a latent curing agent, for example, when a specific temperature is exceeded, the curing agent is released from the microcapsule or salt into the system, and a curing function is exhibited.

  Examples of the latent curing agent include a reaction product of an amine compound and an epoxy compound (amine-epoxy adduct system), a reaction product of an amine compound and an isocyanate compound or a urea compound (urea type adduct system), and the like. Commercial products of latent curing agents include Amicure (Ajinomoto Co., Inc., registered trademark), NovaCure (Asahi Kasei E-Materials Co., Ltd., registered trademark) in which microencapsulated amine is dispersed in phenolic resin, etc. It is done.

  The content of the curing agent in the connection material is not particularly limited, but from the viewpoint of adhesive strength, the content of the curing agent is 10% when the total content of the adhesive and the curing agent is 100% by mass. % To 50% by mass, more preferably 20% to 40% by mass.

(Film forming material)
Examples of the film forming material include phenoxy resin, acrylic resin, polycarbonate resin, acrylic rubber, polyimide resin, polyamide resin, polyurethane resin, polyester resin, polyester urethane resin, and polyvinyl butyral resin, and are phenoxy resin or acrylic rubber. It is preferable.
As a weight average molecular weight of a film forming material, 5000-2 million are preferable, 8000-1500000 are more preferable, and 10000-1000000 are still more preferable.
The weight average molecular weight of the film forming material is measured according to a conventional method using a gel permeation chromatography method (GPC).

  The content of the film-forming material is not particularly limited, but from the viewpoint of the hardness of the produced connection material, ease of peeling from the release film described later, the adhesive, the curing agent, and the film-forming material. The content of the film-forming material is preferably 20% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 70% by mass or less when the total content is 100% by mass.

(Conductive particles)
The connection material can further contain conductive particles. By containing the conductive particles, the power generation performance of the solar cell module can be further improved.
The conductive particles are not particularly limited, and examples thereof include gold particles, silver particles, copper particles, nickel particles, gold-plated nickel particles, gold / nickel-plated plastic particles, copper-plated particles, and nickel particles. It is done. Moreover, when it contains electroconductive particle, it is preferable that the particle diameter (D50%) of electroconductive particle is 1 micrometer-50 micrometers, It is more preferable that they are 1 micrometer-30 micrometers, It is still more preferable that they are 1 micrometer-25 micrometers. . In addition, the measuring method of the particle diameter (D50%) of electroconductive particle is the same as the measuring method of the particle diameter of a phosphorus- tin containing copper alloy particle.
In addition, the content of the conductive particles in the connection material is preferably 1% by volume or more and 15% by volume or less, preferably 2% by volume or more and 12% by volume or less, with the total volume of the connection material being 100% by volume from the viewpoint of conductivity. More preferably, it is not more than volume%, more preferably not less than 3 volume% and not more than 10 volume%.

(Other ingredients)
In addition to the components described above, the connection material can contain a modifying material such as a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent in order to improve adhesion or wettability. Moreover, when adding electroconductive particle, in order to improve the dispersibility, a chelating material etc. for suppressing dispersing agents, such as calcium phosphate and a calcium carbonate, silver, or copper migration, etc. can be contained.

  The connection material can be produced, for example, by applying a coating solution obtained by dissolving or dispersing the above-described various materials in a solvent onto a release film such as a polyethylene terephthalate film and removing the solvent.

<Wiring member>
The electrode connection set may include a wiring member as one of the elements.
The wiring member is not particularly limited, but a solder-coated copper wire (tab wire) for a solar cell can be suitably used. The composition of the solder can include Sn-Pb, Sn-Pb-Ag, Sn-Ag-Cu, etc. In consideration of the influence on the environment, Sn-Ag-Cu based which does not substantially contain lead It is preferable to use solder.

  The thickness of the copper wire of the tab wire is not particularly limited, and 0.05 mm to 0 in view of the difference in thermal expansion coefficient or connection reliability with the solar cell element during the heating and pressing treatment and the resistivity of the tab wire itself. 0.5 mm, preferably 0.1 mm to 0.5 mm.

  Further, the cross-sectional shape of the tab wire is not particularly limited, and any of a rectangular shape (flat tab) and an elliptical shape (round tab) can be applied, and the copper content of the connection material when the connection material is thermocompression bonded. From the viewpoint of penetration into the gap of the electrode, uniformity of pressure during thermocompression bonding, etc., it is preferable to use a rectangular (flat tab) cross-sectional shape.

  The total thickness of the tab wire is not particularly limited, and is preferably 0.1 mm to 0.7 mm, and preferably 0.15 mm to 0.5 mm, from the viewpoint of uniformity of pressure during thermocompression bonding. More preferred.

[Method for manufacturing solar cell]
The manufacturing method of the solar cell of this invention forms an electrode using the said electrode connection set, and connects a wiring member to the obtained electrode.
That is, the manufacturing method of the solar cell includes a step of applying the electrode composition onto a semiconductor substrate having the pn junction (referred to as an electrode composition applying step), and a semiconductor to which the electrode composition is applied. A step of heat-treating (firing) the substrate to form a copper-containing electrode (referred to as an electrode formation step), and a step of laminating the connection material and the wiring member in this order on the copper-containing electrode to obtain a laminate (lamination) And a step of subjecting the laminate to a heat and pressure treatment (referred to as a heat and pressure treatment step).
The solar cell manufacturing method can manufacture a solar cell in which the electrode and the wiring member have high connection strength (adhesion) and high connection reliability.

(Solar cell element manufacturing process)
A solar cell element is obtained by the electrode composition applying step and the electrode forming step.

  In the electrode composition application step, the electrode composition is applied to the region on the semiconductor substrate where the electrode is to be formed. Examples of a method for applying the electrode composition include screen printing, an ink jet method, and a dispenser method. From the viewpoint of productivity, application by screen printing is preferable.

  When the electrode composition is applied by screen printing, the electrode composition preferably has a viscosity in the range of 20 Pa · s to 1000 Pa · s. The viscosity of the electrode composition is measured using a Brookfield HBT viscometer at a temperature of 25 ° C. and a rotational speed of 5.0 rpm.

The application amount of the electrode composition can be appropriately selected according to the size of the copper-containing electrode to be formed. For example, it is possible to ^2g / ^{m 2 ~10g} / m 2 as the application amount of the electrode composition ^is preferably ^{4g / m 2 ~8g / m 2} .

  In the electrode forming step, the semiconductor substrate to which the electrode composition has been applied is heat-treated (fired) after drying. Thereby, the heat processing (baking) of the composition for electrodes is performed, a copper containing electrode is formed in the desired area | region on a semiconductor substrate, and a solar cell element can be obtained. By using the electrode composition, an electrode with low resistivity can be formed even when heat treatment (baking) is performed in the presence of oxygen (for example, in the air).

As a heat treatment (firing) condition for forming a copper-containing electrode on a semiconductor substrate using the electrode composition, a commonly used heat treatment (firing) condition can be applied.
In general, the heat treatment (firing) temperature is 800 ° C. to 900 ° C. However, when the electrode composition is used, a wide range of heat treatment (firing) conditions from a lower temperature heat treatment (firing) condition is used. Can be applied to a range. For example, an electrode having good characteristics can be formed at a wide range of heat treatment (firing) temperatures of 450 ° C. to 900 ° C.
The heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like, and can be, for example, 1 second to 20 seconds.

  As the heat treatment apparatus, any apparatus that can be heated to the above temperature can be used as appropriate, and examples thereof include an infrared heating furnace and a tunnel furnace. An infrared heating furnace is highly efficient because electric energy is directly input to a heating material in the form of electromagnetic waves and is converted into heat energy, and rapid heating is possible in a short time. Furthermore, since there is no product due to combustion and non-contact heating, contamination of the formed electrode can be suppressed. Since the tunnel furnace automatically and continuously conveys the sample from the entrance to the exit and performs heat treatment (firing), it can be more uniformly heat treated (firing) by controlling the division of the furnace body and the conveying speed. From the viewpoint of the power generation performance of the solar cell element, it is preferable to perform heat treatment (firing) with a tunnel furnace.

Hereinafter, although the specific example of the solar cell element of this invention and its manufacturing method are demonstrated, referring drawings, this invention is not limited to this. Moreover, the magnitude | size of the member in each figure is notional, The relative relationship of the magnitude | size between members is not limited to this.
Cross-sectional views showing an example of a typical solar cell element, and outlines of the light receiving surface and the back surface are shown in FIGS.
As shown in a schematic cross-sectional view in FIG. 1, an n ⁺ -type diffusion layer 2 is formed near the surface of one surface of the semiconductor substrate 1, and the light-receiving surface output extraction electrode 4 and the reflection are formed on the n ⁺ -type diffusion layer 2. A prevention layer 3 is formed. A p ⁺ type diffusion layer 7 is formed in the vicinity of the surface of the other surface, and a back surface output extraction electrode 6 and a back surface current collecting electrode 5 are formed on the p ⁺ type diffusion layer 7. Usually, single crystal or polycrystalline silicon is used for the semiconductor substrate 1 of the solar cell element. This semiconductor substrate 1 contains boron or the like and constitutes a p-type semiconductor. Irregularities (also referred to as texture, not shown) are formed on the light receiving surface side by an etching solution containing NaOH and IPA (isopropyl alcohol) in order to suppress reflection of sunlight. Phosphorus or the like is diffused (doped) on the light receiving surface side, the n ⁺ -type diffusion layer 2 is provided with a thickness on the order of submicrons, and a pn junction is formed at the boundary with the p-type bulk portion. . Further, on the light receiving surface side, an antireflection layer 3 such as silicon nitride is provided on the n ⁺ type diffusion layer 2 with a thickness of about 90 nm by PECVD (plasma enhanced chemical vapor deposition) or the like.

Next, the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 provided on the light receiving surface side schematically shown in FIG. 2, and the back surface collecting electrode 5 and the back surface formed on the back surface schematically shown in FIG. A method for forming the output extraction electrode 6 will be described.
The light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, and the back surface output extraction electrode 6 are formed from the electrode composition. The back current collecting electrode 5 is formed of an aluminum electrode composition containing glass powder. As the first method for forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, the back surface output extraction electrode 6 and the back surface current collecting electrode 5, the electrode composition and the aluminum electrode composition are screen printed. For example, it may be formed by applying heat treatment (firing) at a temperature of about 750 ° C. to 900 ° C. in the air after being applied to a desired pattern, etc., and then dried.

At that time, on the light receiving surface side, the glass particles contained in the electrode composition forming the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 react with the antireflection layer 3 (fire-through). Then, the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 and the n ⁺ type diffusion layer 2 are electrically connected (ohmic contact).
In the present invention, by forming the light receiving surface output extraction electrode 4 and the light receiving surface current collecting electrode 8 using the electrode composition, copper is suppressed from being oxidized while containing copper as a conductive metal, A copper-containing electrode with low resistivity is formed with good productivity.
Furthermore, it is preferable that the copper-containing electrode includes a Cu—Sn alloy phase and / or a Cu—Sn—Ni alloy phase and a Sn—PO glass phase, and the Sn—PO glass phase is Cu—. More preferably (not shown) between the Sn alloy phase or Cu—Sn—Ni alloy phase and the semiconductor substrate. As a result, the reaction between copper and the semiconductor substrate is suppressed, and an electrode having low resistivity and excellent adhesion can be formed.

On the back surface side, aluminum in the aluminum electrode composition that forms the back current collecting electrode 5 during heat treatment (firing) diffuses to the back surface of the semiconductor substrate 1 to form the p ⁺ -type diffusion layer 7. Thus, an ohmic contact can be obtained between the semiconductor substrate 1 and the back surface collecting electrode 5 and the back surface output extraction electrode 6.

  As a second method for forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8 and the back surface output extracting electrode 6, the aluminum electrode composition for forming the back surface collecting electrode 5 is first printed and dried. After forming the back surface collecting electrode 5 by heat treatment (baking) at about 750 ° C. to 900 ° C. in the air, the electrode composition is applied to the light receiving surface side and the back surface side, and after drying, from 450 ° C. in the air A method of forming the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8 and the back surface output extraction electrode 6 by heat treatment (baking) at about 650 ° C. can be mentioned.

This method is effective in the following cases, for example. That is, when the aluminum electrode composition for forming the back surface collecting electrode 5 is heat-treated (fired), at a heat treatment (baking) temperature of 650 ° C. or less, the aluminum particles are fired depending on the composition of the aluminum electrode composition. As a result, the amount of aluminum diffused into the semiconductor substrate 1 may be insufficient, and the p ⁺ -type diffusion layer may not be sufficiently formed. In this state, an ohmic contact cannot be sufficiently formed between the semiconductor substrate 1 on the back surface, the back surface collecting electrode 5 and the back surface output extraction electrode 6, and the power generation performance as a solar cell element may be lowered. Therefore, after forming the back current collecting electrode 5 at an optimum heat treatment (firing) temperature (for example, 750 ° C. to 900 ° C.) for the aluminum electrode composition, the electrode composition is applied, and after drying, the temperature is relatively low ( For example, the light receiving surface output extraction electrode 4, the light receiving surface current collecting electrode 8, and the back surface output extraction electrode 6 are preferably formed by heat treatment (baking) at 450 ° C. to 650 ° C.
Regardless of which method is selected, the thickness of the light-receiving surface collecting electrode 8 and the back surface output extraction electrode 6 obtained after the heat treatment (firing) is, for example, 3 μm to 50 μm, preferably 5 μm to 30 μm. Can do. In addition, the thickness of the layer or laminated body in this invention measures the thickness of five points of the layer or laminated body used as object, and makes it the value given as the arithmetic mean value. The thickness of a layer or a laminated body shall be measured using the micrometer.

  Further, as shown in the plan view of FIG. 3, the solar cell element can take a form in which the light receiving surface output extraction electrode 4 is not formed. The solar cell element shown in FIG. 3 can be manufactured in the same manner as the solar cell element having the structure shown in FIGS. This can be considered as follows, for example.

  In the present invention, since the connection material is used, the object to which the wiring member is connected does not need solder wettability as described above. In the present invention, by using the connection material, the antireflection layer 3 formed on the semiconductor substrate 1 and the wiring member can be firmly adhered. The electrical connection between the light receiving surface current collecting electrode 8 and the wiring member on the light receiving surface of the solar cell element is a portion where the light receiving surface current collecting electrode 8 and the wiring member are in direct contact with each other due to the flow exclusion of the connecting material. When the connection material contains conductive particles, the light receiving surface collecting electrode 8 and the wiring member are formed by forming a portion in contact with the conductive particles through thermocompression bonding. Is done.

(Solar cell manufacturing process)
Using the solar cell element obtained as described above, a solar cell including the solar cell element is further obtained by the laminating step and the heat and pressure treatment step.
More specifically, the solar cell of the present invention has a structure in which a conductive layer including a metal part including copper, a glass part, and a connection material is interposed between a semiconductor substrate and a wiring member. The conductive layer has a structure in which the copper-containing electrode including the metal part and the glass part is in contact with the wiring member thereon, and a structure in which a part of the connection material enters the gap of the copper-containing electrode. By having a structure in which the copper-containing electrode and the wiring member are in direct contact with each other, the connection reliability can be improved, and by having a structure in which a part of the connection material enters the void portion of the copper-containing electrode, Adhesion between the containing electrode and the wiring member is improved.

Next, although the specific example of the solar cell of this invention and its manufacturing method are demonstrated, referring FIGS. 5-7, this invention is not limited to this. Moreover, the magnitude | size of the member in each figure is notional, The relative relationship of the magnitude | size between members is not limited to this.
As shown in FIGS. 5 to 7, the connection material 10 and the wiring member 9 are arranged in this order on the light receiving surface output extraction electrode 4 and the back surface output extraction electrode 6 to obtain a laminate (lamination process). By subjecting the laminated body to heat pressure treatment (thermocompression treatment), the light receiving surface output extraction electrode 4 and the wiring member 9 are pressure bonded, and the back surface output extraction electrode 6 and the wiring member 9 are pressure bonded to form a solar cell. Is done. When connecting a plurality of the solar cells, the wiring member 9 has a light receiving surface output extraction electrode 4 of one solar cell element at one end and a back surface output extraction electrode 6 of another solar cell element at the other end, respectively. 9 may be arranged so as to be connected via 9. In the case of manufacturing a solar cell, a solar cell element in which the light receiving surface output extraction electrode 4 is not formed can be used as shown in FIG.

Moreover, when manufacturing the solar cell of this invention, the heat press treatment conditions normally used in the said technical field can be applied as conditions for carrying out the thermocompression bonding of the said electrode and wiring member.
In general, the heating temperature is preferably 150 ° C. or higher and 200 ° C. or lower, and more preferably 150 ° C. or higher and 190 ° C. or lower. The pressure during pressure bonding is preferably 0.1 MPa or more and 4.0 MPa or less, and more preferably 0.5 MPa or more and 3.5 MPa or less. The heating and pressurizing time is preferably 3 seconds or more and 30 seconds or less, and more preferably 4 seconds or more and 20 seconds or less. By performing the heating and pressurizing treatment under the above conditions, the connection material can easily enter the gap of the copper-containing electrode, the adhesive force between the electrode and the wiring member is improved, and the connection material is efficiently eliminated. This facilitates direct contact between the electrode and the wiring member, and as a result, the electrical contact resistance between the electrode and the wiring member can be reduced.
The direction of pressurization may be any direction as long as pressure is applied at least in the stacking direction of the electrode and the wiring member to bond the electrode and the wiring member.

  As the thermocompression bonding apparatus, any apparatus capable of applying the above temperature and pressure can be adopted as appropriate. For example, a thermocompression bonding machine including a pressure bonding head having a heating mechanism can be suitably used. In this case, it is particularly preferable that the pressure of the pressure-bonding head ((target pressure) × (adhesion area)) can be appropriately set from the target pressure and the adhesion area.

[Structure of solar cell]
A solar cell manufactured using the electrode connection set includes a semiconductor substrate, an electrode formed on the semiconductor substrate, and a wiring member disposed on the electrode. The electrode includes a metal part and glass. And a portion corresponding to a void formed by heat treatment (firing) during electrode formation. The solar cell has a partial structure in which a conductive layer including a metal part, a glass part and a connection material and a wiring member are stacked on a semiconductor substrate as a wiring connection part.
Due to the heat treatment (firing) at the time of electrode formation, voids in the copper-containing electrode are generated irregularly and in an arbitrary shape, and the contour of the metal part constituting the electrode becomes nonuniform due to the formation of the voids. At the time of thermocompression bonding between the electrode and the wiring member, the connection material enters the gap from the connection material application surface, that is, the wiring member side. As a result, a conductive layer including a metal part, a glass part, and a connection material that has entered a part corresponding to the gap is formed between the semiconductor substrate and the wiring member in the wiring connection part. In the conductive layer, the connection material penetrates into the gap.

  In such a solar cell, for example, when the cross section in the stacking direction of the semiconductor substrate, the conductive layer, and the wiring member is observed, the boundary line between the electrode and the connection material is irregularly bent (see FIG. 8). ). The presence of the boundary line between the electrode and the connection material exhibiting the irregular bending state can be confirmed using, for example, a cross section (observation cross section) parallel to the stacking direction of the semiconductor substrate, the conductive layer, and the wiring member. .

  The observation cross section applied to confirm the shape inside the conductive layer is the two sides along the direction parallel to the stacking direction of the semiconductor substrate, conductive layer and wiring member, and the stacking direction of the semiconductor substrate, conductive layer and wiring member. And a rectangular shape surrounded by two sides along the vertical direction. In this observation cross section, the length of the side in the direction parallel to the stacking direction of the semiconductor substrate, the conductive layer, and the wiring member is “height”, and the direction perpendicular to the stacking direction of the semiconductor substrate, the conductive layer, and the wiring member is The length is “width”. The observation cross section only needs to include at least a conductive layer and at least a part of each of the wiring member and the semiconductor substrate sandwiching the conductive layer.

The size of the observation cross section varies depending on the size of the solar cell. For example, the width may be 100 μm to 500 μm, and the height may be any length larger than the thickness of the conductive layer, for example, 50 μm to 500 μm. it can. In addition, the observation cross section is not particularly limited as long as it is an observation cross section at the wiring connection portion, and is an observation cross section (for example, the area of the conductive layer in the observation cross section where the end portion of the solar cell or the connection material is extremely small or extremely large) On the other hand, it is preferable to exclude the area of the connecting material from 2% or less or 98% or more from the confirmation target.
When such an observation cross section is used, the shape of the copper-containing electrode in the wiring connection portion can be confirmed as follows.

  In the observation cross section of the wiring connection portion, the total boundary line length including the total boundary line between the electrode and the connection material and the total boundary line between the electrode and the wiring member is the length of the width of the observation cross section. It can be confirmed by being longer than the length L (FIG. 8).

  Further, in the observation cross section of the wiring connection portion, a line segment from a boundary line between the wiring member and the conductive layer to a glass portion or a metal portion that first contacts is drawn in a direction parallel to the height direction of the observation cross section. Can be confirmed by obtaining a plurality of line segments having different lengths (for example, line segment D1 and line segment D2 in FIG. 8).

Moreover, in the said wiring connection part, you may have a part which the electrode is in contact with the wiring member (FIG. 8, frame C). Such a portion where the electrode and the wiring member are in contact with each other is considered to be obtained by removing the connecting material from between the electrode and the wiring member by heat and pressure treatment. In the portion where the electrode and the wiring member are in direct contact with each other, the electrode and the wiring member are in a good connection state, so that the wiring member and the electrode can be electrically connected.
If there is a part where the electrode and the wiring member are in direct contact, the shape of the electrode can be determined by comparing the total length of the boundary line between the electrode and the connecting material or wiring member and the length in the width direction of the observation cross section. It is preferable to confirm.

In the solar cell according to the present invention, the irregular uneven state of the boundary surface between the electrode and the resin part that provides good connection strength between the electrode and the wiring member may be specified by the surface roughness of the electrode.
In this case, the arithmetic average roughness Ra of the electrode surface is preferably 0.8 or more and 6.3 or less. The arithmetic average roughness Ra can be obtained by measuring by the method described in JIS B 0601-2001. Specifically, using a surface shape measuring instrument (Mitutoyo Co., Ltd., trade name: Form Tracer SV-C3000, etc.), the surface of the electrode formed on the semiconductor substrate is laminated before or after the wiring member is laminated. After removing the wiring member and the resin portion, the arithmetic average roughness Ra can be directly measured.

[Solar cell module]
The solar cell module of the present invention includes a solar cell obtained by using the electrode connection set and a sealing material that seals the solar cell so that a part of the wiring member in the solar cell is exposed. And.
In the solar cell module, for example, a plurality of the solar cells are connected in series and / or in parallel as necessary, sandwiched with tempered glass or the like for environmental resistance, the gap is filled with a transparent resin, and exposed. The thing provided with the wiring member made as an external terminal is included.

  As a manufacturing method of a solar cell module, for example, as shown in FIG. 9, a glass plate 11, a sealing material 12, a solar cell 14 provided with a wiring member 9, a sealing material 12, and a back sheet 13 are used. A general method including a sealing step that is arranged in this order and is sealed with a vacuum laminator or the like can be suitably used. Lamination conditions are determined depending on the type of sealing material, but are preferably maintained at 130 ° C. to 160 ° C. for 3 minutes or more, more preferably 135 ° C. to 150 ° C. for 3 minutes or more.

  Examples of the glass plate 11 include white plate tempered glass with dimples for solar cells. Examples of the sealing material 12 include an EVA sheet containing ethylene vinyl acetate (EVA). Examples of the back sheet 13 include polyethylene terephthalate (PET) -based or Tedlar-PET laminated material, metal foil-PET laminated material, and the like.

[Method for Manufacturing Semiconductor Device]
In the method for manufacturing a semiconductor device of the present invention, an electrode is formed using the electrode connection set, and a wiring member is connected to the obtained electrode.
That is, the manufacturing method of the semiconductor device includes a step of applying the electrode composition onto a semiconductor substrate (referred to as an electrode composition applying step), and a heat treatment (firing) of the semiconductor substrate to which the electrode composition is applied. ), Forming a copper-containing electrode (referred to as an electrode forming step), laminating the connection material and the wiring member in this order on the copper-containing electrode, and obtaining a laminate (referred to as a laminating step), A step of subjecting the laminate to a heat and pressure treatment (referred to as a heat and pressure treatment step).
By the semiconductor device manufacturing method, a semiconductor device in which the electrode and the wiring member have high connection strength (adhesion) and high connection reliability can be manufactured.

[Semiconductor device]
A semiconductor device manufactured using the electrode connection set includes a semiconductor substrate, an electrode formed on the semiconductor substrate, and a wiring member disposed on the electrode. The electrode includes a metal portion and glass. And a portion corresponding to a void formed by heat treatment (firing) during electrode formation. The semiconductor device has a partial structure in which a conductive layer including a metal part, a glass part and a connection material and a wiring member are stacked on a semiconductor substrate as a wiring connection part.
In this case, examples of the wiring member include a circuit member having a circuit or an electrode portion.

[Method of manufacturing electronic parts]
The manufacturing method of the electronic component of this invention forms an electrode using the said electrode connection set, and connects a wiring member to the obtained electrode.
That is, the method of manufacturing the electronic component includes a step of applying the electrode composition onto a substrate (referred to as an electrode composition application step), and a heat treatment (firing) of the substrate to which the electrode composition is applied. Then, a step of forming a copper-containing electrode (referred to as an electrode forming step), a step of stacking the connection material and the wiring member on the copper-containing electrode in this order to obtain a laminated body (referred to as a stacking step), and the lamination And a step of subjecting the body to heat and pressure treatment (referred to as a heat and pressure treatment step).
By the method for manufacturing an electronic component, an electronic component in which the electrode and the wiring member have high connection strength (adhesion) and high connection reliability can be manufactured.

[Electronic parts]
An electronic component manufactured using the electrode connection set includes a substrate, an electrode formed on the substrate, and a wiring member disposed on the electrode. The electrode includes a metal part and a glass part. And a portion corresponding to a void formed by heat treatment (firing) during electrode formation. The electronic component has a partial structure in which a conductive layer including a metal part, a glass part and a connection material and a wiring member are stacked on a substrate as a wiring connection part.
In this case, examples of the wiring member include a circuit member having a circuit or an electrode portion.

The semiconductor device of the present invention can be used for various electronic devices. The semiconductor device of the present invention has excellent adhesion between the electrode and the wiring member, and is excellent in reliability. Details and preferred aspects of the configuration, materials, etc. relating to the semiconductor device of the present invention are the same as details and preferred aspects of the configuration, materials, etc. relating to the solar cell of the present invention described above.
Moreover, the electronic component of the present invention can be used for various electronic devices. The electronic component of this invention is excellent in the adhesiveness between an electrode and a wiring member, and is excellent in reliability. Details and preferred aspects of the configuration, materials, and the like relating to the electronic component of the present invention are the same as details and preferred aspects of the configuration, materials, etc. relating to the solar cell of the present invention described above.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these embodiment.

<Example 1>
(A) Preparation of electrode composition A phosphorus-tin-containing copper alloy containing 6% by mass of phosphorus and 15% by mass of tin is prepared by a conventional method, dissolved and powdered by a water atomization method, and then dried. And classified. For classification, a Nisshin Engineering Co., Ltd., forced vortex classifier (turbo classifier; TC-15) was used. The classified powder was blended with an inert gas, and deoxidized and dehydrated to produce phosphorus-tin-containing copper alloy particles containing 6% by mass of phosphorus and 15% by mass of tin. The particle diameter (D50%) of the phosphorus-tin-containing copper alloy particles was 5.0 μm, and the shape thereof was substantially spherical.

Silicon _(SiO 2) 3 parts by weight dioxide, lead oxide (PbO) 60 parts by mass, 18 parts by weight of boron oxide _{(B 2} O 3), bismuth oxide _{(Bi 2 O} 3) 5 parts by weight, aluminum oxide _(Al 2 _{O 3} ) 5 parts by mass and 9 parts by mass of zinc oxide (ZnO) (hereinafter, sometimes abbreviated as “G01”) were prepared. The obtained glass G01 had a softening temperature of 420 ° C. and a crystallization start temperature of over 650 ° C.
By using the obtained glass G01, glass G01 particles having a particle diameter (D50%) of 2.5 μm were obtained. The shape was substantially spherical.

  The shapes of the phosphorus-tin-containing copper alloy particles and the glass particles were determined by observing using Hitachi High-Technologies Corporation, TM-1000 scanning electron microscope. The particle diameters of the phosphorus-tin-containing copper alloy particles and the glass particles were calculated using a Beckman Coulter, Inc., LS 13 320 type laser scattering diffraction particle size distribution analyzer (measurement wavelength: 630 nm). The softening temperature and crystallization start temperature of the glass were obtained from a differential heat (DTA) curve using a Shimadzu Corporation, DTG-60H type differential thermal-thermogravimetric simultaneous measurement apparatus. Specifically, in the DTA curve, the softening point can be estimated from the endothermic part, and the crystallization start temperature can be estimated from the heat generating part.

  72.0 parts by mass of the phosphorus-tin-containing copper alloy particles obtained above, 8.0 parts by mass of glass G01 particles, 20.0 parts by mass of diethylene glycol monobutyl ether (BC), and polyethyl acrylate (EPA) Was mixed using an automatic mortar kneader to make a paste, and an electrode composition 1 was prepared. When the viscosity of the obtained composition 1 for electrodes was measured on the conditions of the temperature of 25 degreeC, and rotation speed 5.0rpm using the Brookfield HBT viscometer, it was 31 Pa.s.

(B) Preparation of connecting material Acrylic rubber (product name: KS8200H, Hitachi Chemical Co., Ltd.) obtained by copolymerizing 40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, and 3 parts by mass of glycidyl methacrylate. Co., Ltd.), 125 g of weight average molecular weight: 850,000) and 50 g of phenoxy resin (product name: PKHC, Union Carbide, weight average molecular weight 45,000) are dissolved in 400 g of ethyl acetate to obtain a 30% by mass solution. It was. Next, 325 g of a liquid epoxy resin (Novacure HX-3941HP, Asahi Kasei E-Materials Co., Ltd., epoxy equivalent 185) containing a microcapsule-type latent curing agent is added to this solution and stirred to obtain an adhesive composition. It was. Further, 56 g of Ni particles having a diameter of about 10 μm were added to the adhesive composition and stirred.

  The adhesive composition obtained above was applied onto a polyethylene terephthalate film using an applicator (YOSHIMITSU SEIKI, Irie Shokai Co., Ltd.), dried on a hot plate at a temperature of 70 ° C. for 10 minutes, and a connection material A connection material 1 having a thickness of 25 μm was prepared. In addition, the thickness of the connection material was measured using a micrometer (Mitutoyo Corporation, ID-C112). The viscosity of the connecting material 1 was 9800 Pa · s when measured under the conditions of 25 ° C. and a frequency of 10 Hz using a TS Instrument Japan Co., Ltd. and a shear viscometer measuring device (ARES). .

(C) Production of Solar Cell Element The electrode composition 1 and the connection material 1 obtained in the above (a) and (b) were prepared as an electrode connection set.
Further, in addition to the electrode connection set, as a wiring member, a solder plating rectangular wire for a solar cell (product name: SSA-TPS L 0.2 × 1.5 (10), thickness 0.2 mm × width 1.5 mm) Hitachi Metals Co., Ltd., which has a copper wire plated with Sn-Ag-Cu-based lead-free solder with a thickness of 10 μm on one side, was prepared.
Using these, solar cell elements were produced as follows.

First, a p-type silicon substrate having a thickness of 190 μm in which an n ⁺ -type diffusion layer, a texture, and an antireflection layer (silicon nitride layer) were formed on the light receiving surface was prepared, and two pieces were cut into a size of 125 mm × 125 mm. On the light receiving surface, the electrode composition 1 was printed using a screen printing method so as to form an electrode pattern as shown in FIG. The electrode pattern is composed of a light receiving surface collecting electrode having a width of 150 μm and a light receiving surface output extraction electrode having a width of 1.5 mm, and the thickness of each of the light receiving surface collecting electrode and the light receiving surface output extraction electrode after heat treatment (firing) is 20 μm. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were adjusted as appropriate. This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.

Subsequently, an electrode composition 1 as an electrode composition and an aluminum electrode composition (PVG Solutions Inc., PVG-AD) on a surface opposite to the light-receiving surface (hereinafter also referred to as “back surface”). −02) was printed by screen printing in the same manner as described above so as to obtain an electrode pattern as shown in FIG.
The pattern of the back surface output extraction electrode formed using the electrode composition 1 was composed of 123 mm × 5 mm, and was printed in two places in total. The printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were appropriately adjusted so that the back surface output extraction electrode had a thickness after heat treatment (firing) of 20 μm. Moreover, the composition for aluminum electrodes was printed on the whole surface except the back surface output extraction electrode, and the back surface current collection electrode pattern was formed. Further, the printing conditions (screen plate mesh, printing speed, printing pressure, etc.) of the aluminum electrode composition were appropriately adjusted so that the thickness of the back surface collecting electrode after heat treatment (firing) was 20 μm. This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.

  Subsequently, using a tunnel furnace (Noritake Co., Ltd., single row W / B tunnel furnace), heat treatment (firing) was performed at a maximum temperature of 800 ° C. and a holding time of 10 seconds (firing) in an air atmosphere. Thus, two solar cell elements 1 on which desired electrodes were formed (one for peel strength evaluation and one for power generation performance evaluation) were produced.

  The connection material 1 is cut into the width (1.5 mm) of the light receiving surface output extraction electrode of the solar cell element 1, and between the prepared wiring member and the light receiving surface output extraction electrode and the back surface output extraction electrode of the solar cell element 1. In each, the cut connection material 1 was disposed. Next, using a thermocompression bonding machine (device name: MB-200WH, Hitachi Chemical Co., Ltd.), thermocompression bonding is performed under the conditions of 180 ° C., 2 MPa, 10 seconds, and the electrode and the wiring member are connected via the connection material 1. Two solar cells 1 having a connected structure were produced.

(D) Production of solar cell module About one of the obtained solar cells 1 (one for power generation performance evaluation), tempered glass (product name: white plate tempered glass 3KWE33, Asahi Glass Co., Ltd.), ethylene vinyl acetate (EVA), using a back sheet, as shown in FIG. 9, glass (glass plate 11) / EVA (sealing material 12) / solar cell 1 (solar cell 14) / EVA (sealing material 12) / back Sheet (back sheet 13) is laminated in this order, and this laminate is 140 ° C. so that a part of the wiring member is exposed using a vacuum laminator (device name: LM-50 × 50, NPC Corporation). A solar cell module 1 was produced by vacuum lamination at a temperature of 5 minutes.

(E) Cross-sectional shape of solar cell A portion (wiring connection portion) to which the wiring member of the obtained solar cell 1 is connected is a solar cell element using an RCO-961 type diamond cutter (Refinetech Co., Ltd.). 1 and the wiring member were cut in parallel to the stacking direction. The SEM photograph of the obtained cross section was obtained using SEM (Hitachi High-Technologies Corporation, TM-1000 scanning electron microscope).
The observation cross section has a rectangular shape of 300 μm × 250 μm, where the length in the cutting direction is the height, the length in the direction parallel to the cutting direction is the width, and the area of the connection material is relative to the area of the conductive layer in the observation cross section. The observation cross section was selected to be 2% or less, or 98% or less.
In the observation cross section, the total length of the boundary line between the connection material and the electrode was measured using Adobe illustrator CS6. Measurements were performed at an magnification of about 10,000 times the actual sectional view. The line segment corresponding to the length of the boundary line was traced with the “pencil tool” and the length was measured by using the “object tool”. The width of the observation cross section was measured by drawing a straight line having the same length as the width of the observation cross section with the “Line Tool” and using the “Object Tool”. The lengths of the line segment corresponding to the obtained boundary line length and the line segment corresponding to the width of the observation cross section were compared.

In addition, about the composition of the composition 1 for electrodes, it shows in Table 1 and the structure of the solar cell 1 and the solar cell module 1 in Table 2 and Table 3, respectively. The same applies hereinafter.
In Tables 2 and 3, “◯” in the column of “Applied electrode” means that the target electrode is used, and “-” means that the target electrode is not used. Means that. “-” In the other column means that there is no corresponding item.

<Examples 2 to 5>
In Example 1, phosphorus content of copper alloy particles, tin content and nickel content, particle size (D50%) and content thereof, composition of nickel-containing particles, particle size (D50%) and content thereof, glass Composition 1 for electrodes except having changed the kind of particle | grain, particle diameter (D50%) and its content, the kind and content of a solvent, and the kind and content of resin as shown in Table 1. In the same manner, electrode compositions 2 to 5 were prepared.
Glass G02 is composed of 45 parts by mass of vanadium oxide (V ₂ O ₅ ), 24.2 parts by mass of phosphorus oxide (P ₂ O ₅ ), 20.8 parts by mass of barium oxide (BaO), and antimony oxide (Sb ₂ O ₃ ). 5 parts by weight, and was prepared as consisting of tungsten oxide (WO 3) ₅ parts by weight. The softening temperature of this glass G02 was 492 ° C., and the crystallization start temperature exceeded 650 ° C.

  Then, using the obtained electrode compositions 2 to 5 respectively, the heat treatment (firing) conditions (maximum temperature and holding time) and the like were changed to the conditions shown in Tables 2 and 3, and the same as in Example 1. Thus, solar cell elements 2 to 5, solar cells 2 to 5 and solar cell modules 2 to 5 were produced.

<Example 6>
In Example 1, a solar cell 6 and a solar cell module 6 were produced in the same manner as in Example 1 except that the connection material was changed from the connection material 1 to the connection material 2. The connection material 2 was produced in the same manner as the connection material 1 except that it did not contain Ni particles as conductive particles. The viscosity of the connecting material 2 was 9500 Pa · s as measured in the same manner as the connecting material 1.

<Example 7>
In Example 1, the electrode composition 1 was applied to form the light receiving surface current collecting electrode and the light receiving surface output extraction electrode, and the back surface output extraction electrode was formed as follows. Except having applied the electrode composition 6, it carried out similarly to Example 1, and produced the solar cell element 7, the solar cell 7, and the solar cell module 7, respectively.

The electrode composition 6 was prepared in the same manner as the electrode composition 5 except that the composition of the glass particles was changed from the glass G01 to the glass G03 shown below.
Glass G03 is composed of 10 parts by mass of silicon dioxide (SiO ₂ ), 38 parts by mass of boron oxide (B ₂ O ₃ ), 28 parts by mass of zinc oxide (ZnO), 12 parts by mass of aluminum oxide (Al ₂ O ₃ ), and oxidation. It prepared so that it might consist of 12 mass parts of barium (BaO). The obtained glass G03 had a softening temperature of 583 ° C. and a crystallization start temperature of over 650 ° C.

<Example 8>
In Example 7, a solar cell element 8, a solar cell 8, and a solar cell were formed in the same manner as in Example 7 except that the electrode composition 7 shown below was applied to form the back surface output extraction electrode. Modules 8 were produced respectively.

The electrode composition 7 was prepared in the same manner as the electrode composition 5 except that the composition of the glass particles was changed from the glass G01 to the glass G04 shown below.
Glass G04 was prepared so as to consist of 12.8 parts by mass of boron oxide, 8.7 parts by mass of silicon dioxide, and 78.5 parts by mass of bismuth oxide. The softening temperature of this glass G04 was 451 ° C., and the crystallization start temperature exceeded 650 ° C.

<Example 9>
In Example 1, an electrode composition 8 was prepared in the same manner as in Example 1 except that the solvent and the resin of the electrode composition 1 were changed as shown in Table 1. Subsequently, using this, a solar cell element 9, a solar cell 9, and a solar cell module 9 were respectively produced in the same manner as in Example 1.
The solvent Ter in the table represents terpineol, and the resin EC represents ethyl cellulose.

<Example 10>
A p-type silicon substrate having a thickness of 190 μm in which an n ⁺ -type diffusion layer, a texture, and an antireflection layer (silicon nitride layer) were formed on the light receiving surface was prepared, and two pieces were cut into a size of 125 mm × 125 mm. Thereafter, an aluminum electrode composition (PVG Solutions, PVG-AD-02) was printed on the back surface to form a back surface collecting electrode pattern. The back surface collecting electrode pattern was printed on the entire surface other than the back surface output extraction electrode as shown in FIG. Also, the printing conditions (screen plate mesh, printing speed, printing pressure, etc.) of the aluminum electrode composition were appropriately adjusted so that the thickness of the back surface collecting electrode after heat treatment (firing) was 30 μm. This was placed in an oven heated to 150 ° C. for 15 minutes, and the solvent was removed by evaporation.
Subsequently, using a tunnel furnace (Noritake Co., Ltd., single-row transport W / B tunnel furnace), heat treatment (firing) was performed at a maximum temperature of 800 ° C. and a holding time of 10 seconds (firing) in an air atmosphere. Then, a current collecting electrode on the back surface and a p ⁺ type diffusion layer were formed.

  Thereafter, the electrode composition 1 obtained as described above was printed so as to have the pattern of the light-receiving surface current collecting electrode, the light-receiving surface output extraction electrode, and the back surface output extraction electrode shown in FIGS. The electrode pattern is composed of a light receiving surface collecting electrode having a width of 150 μm and a light receiving surface output extraction electrode having a width of 1.5 mm, and printing conditions (screen plate mesh, The printing speed, printing pressure, etc.) were adjusted as appropriate. The pattern of the back surface output extraction electrode was 123 mm × 5 mm, and was printed in two places in total. Printing conditions (screen plate mesh, printing speed, printing pressure, etc.) were appropriately adjusted so that the thickness after heat treatment (firing) was 20 μm. This was placed in an oven heated to 150 ° C., and the solvent was removed by evaporation.

  Next, using a tunnel furnace (Noritake Co., Ltd., 1-row transport W / B tunnel furnace), heat treatment (firing) was performed in an air atmosphere at a maximum heat treatment (firing) temperature of 650 ° C. and a holding time of 10 seconds. Two solar cell elements 10 on which desired electrodes were formed were produced. Thereafter, in the same manner as in Example 1, a solar cell 10 and a solar cell module 10 were produced.

<Example 11>
Example 10 is the same as Example 10 except that the electrode composition for forming the light receiving surface collecting electrode, the light receiving surface output extraction electrode, and the back surface output extraction electrode is changed to the electrode composition 5. Thus, two solar cell elements 11 were produced. Thereafter, in the same manner as in Example 10, a solar cell 11 and a solar cell module 11 were produced.

<Example 12>
In Example 5, the solar cell 12 and the solar cell module 12 were formed in the same manner as in Example 5 except that the light receiving surface output extraction electrode was not formed and a light receiving surface electrode pattern as shown in FIG. 3 was applied. Produced.

<Comparative Example 1>
In the production of the solar cell in Example 1, the solar cell C1 and the solar cell were obtained in the same manner as in Example 1 except that solder melting was used to connect the light receiving surface output extraction electrode and the back surface output extraction electrode to the wiring member. Battery module C1 was produced. Specifically, flux (product name: Deltalux, Senju Metal Industry Co., Ltd.) is applied to the electrode surface of the solar cell element 1, and then Sn—Ag—Cu based lead-free solder is melted at a temperature of 240 ° C. Then, wiring members were arranged and connected.

<Comparative Example 2>
In the preparation of the electrode composition in Example 1, as shown in Table 1, an electrode composition C2 using silver particles was prepared without using copper alloy particles. Except having used the composition C2 for electrodes, it carried out similarly to Example 1, and produced the solar cell element C2, the solar cell C2, and the solar cell module C2.

<Comparative Example 3>
In the production of the solar cell in Example 1, the solar cell was formed in the same manner as in Example 1 except that the following conductive paste was used to connect the light receiving surface output extraction electrode and the back surface output extraction electrode to the wiring member. Battery C3 and solar cell module C3 were produced.
Specifically, 78.0 parts by mass of silver particles (Ag; particle diameter (D50%) is 3.0 μm; purity 99.8% by mass), 3.5 parts by mass of polyethylenedioxythiophene, and 1 epoxy resin .2 parts by mass and 17.3 parts by mass of N-methyl-2-pyrrolidone (NMP) were mixed and mixed using an automatic mortar kneader to prepare a paste. Next, the conductive paste is applied to the electrode surface of the solar cell element, and a wiring member (SSA-TPS L 0.2 × 1.5 (10)) is disposed thereon, and this is placed at a temperature of 150 ° C. for 15 minutes. The conductive paste was cured by heating, and the solar cell element electrode and the wiring member were connected.

<Comparative Example 4>
In Example 1, without using glass particles, the phosphorus content and tin content of the copper alloy particles, the particle diameter (D50%) and the content thereof, the type and content of the solvent, and the type and content of the resin An electrode composition C1 was prepared in the same manner as in Example 1 except that the amount was changed as shown in Table 1.

  Next, using the obtained electrode composition C1, a solar cell element C4, a solar cell C4, and a solar cell module C4 were produced in the same manner as in Example 1.

<Comparative Example 5>
In Example 1, the phosphorus content of the copper alloy particles, the particle size (D50%) and the content thereof, the composition of the nickel-containing particles, the particle size (D50%) and the content thereof, the type of glass particles, the particle size (D50) %) And the content thereof, the type and content of the solvent, and the type and content of the resin were changed as shown in Table 1, and the electrode composition C3 was prepared in the same manner as in Example 1. Prepared.

Next, using the obtained electrode composition C3, a solar cell element C5, a solar cell C5, and a solar cell module C5 were produced in the same manner as in Example 1.
In Table 1, “part” represents “part by mass”.

<Evaluation>
(Peel strength)
For one of the produced solar cells, the peel strength of the wiring member connected to the light receiving surface output extraction electrode and the back surface output extraction electrode was measured. The peel strength of the wiring member was determined by measuring the 90 ° peel adhesion strength of the wiring member using a desktop peel tester (device name: EZ-S, Shimadzu Corporation). The measurement was performed in accordance with JIS K 6854-1: 1999; Adhesive-peeling adhesion strength test method, and the tensile speed of the wiring member was 50 mm / min, and the tensile distance of the wiring member was 100 mm. For each test, a wiring member tensile distance-test force curve was plotted, and the average value of the test force at tensile distances of 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm was taken as the peel adhesion strength. The obtained values are converted into relative values with the measured value of Comparative Example 1 (solar cell C1) as 100.0 and are shown in Table 4.

(Power generation performance)
Moreover, about another one of the produced solar cells, a solar cell module was produced as described above, and the power generation performance was evaluated. The evaluation is simulated sunlight (device name: WXS-155S-10, Wacom Denso Co., Ltd.) and voltage-current (IV) evaluation measuring device (device name: IV CURVE TRACER MP-160, Hidehiro) The measurement device of Seiki Co., Ltd.) was used in combination. Jsc (short-circuit current), Voc (open circuit voltage), FF (fill factor), and Eff (conversion efficiency) indicating power generation performance as a solar cell are JIS-C-8913: 2005 and JIS-C-8914: 2005, respectively. It was obtained by performing the measurement in conformity. The obtained measured values are shown in Table 4 in terms of relative values with the measured value of Comparative Example 1 (solar cell module C1) as 100.0.

  The peel strength of the wiring member in the solar cells produced in Examples 1 to 12 was higher than the measured value of Comparative Example 1. This is probably because the connecting material efficiently enters the void portion of the copper-containing electrode formed in the present invention, and the mechanical adhesive strength is improved by the anchor effect. On the other hand, for Comparative Example 2, it was found that the peel strength of the wiring member was lower than the measured value of Comparative Example 1. This is considered to be because the formed electrode contained almost no void portion and a sufficient anchor effect by the adhesive was not obtained.

  Also in Comparative Example 3, the peel strength of the wiring member was lower than the measured value of Comparative Example 1. This is probably because the electrode and the wiring member are connected with a conductive paste, and the conductive particles in the conductive paste are insufficiently sintered, so that the mechanical strength cannot be maintained. For the same reason, since a large amount of contact resistance component between the conductive particles is contained, the resistivity at the wiring connection portion also increases, and as a result, it is considered that the power generation performance is lowered.

  Further, the power generation performance of the solar cell modules produced in Examples 1 to 12 was almost the same as the measured value of Comparative Example 1. In particular, the solar cell module 12 showed high power generation performance even though the light receiving surface output extraction electrode was not formed. For this reason, the connection material is eliminated by thermocompression bonding, and the wiring member has a portion that is in direct contact with not only the light receiving surface and the back surface output extraction electrode, but also the light receiving surface current collecting electrode. It is considered that conductivity is obtained.

  Moreover, in the observation cross section as a cross section parallel to the stacking direction of the wiring connection portion of the solar cell manufactured in Example 1, the electrode having a nonuniform shape is irregularly arranged on the silicon substrate, and the connection material and the electrode The boundary line was irregularly bent in the width direction of the observation cross section according to the contour of the electrode having an uneven shape. The total length of this boundary line was longer than the width of the observation cross section. Examples 2 to 12 were the same.

  In Comparative Examples 4 and 5, the peel strength of the wiring member and the power generation performance of the solar cell module were both lower than the measured values of Example 1.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 n ⁺ type | mold diffused layer 3 Antireflection layer 4 Light reception surface output extraction electrode 5 Back surface collection electrode 6 Back surface output extraction electrode 7 p ⁺ type diffusion layer 8 Light reception surface collection electrode 9 Wiring member 10 Connection material 11 Glass plate 12 Sealing material 13 Back sheet 14 Solar cell

Claims (10)

An electrode composition comprising phosphorus-tin-containing copper alloy particles and glass particles;
A connection material including an adhesive;
Including electrode connection set.   The electrode connection set according to claim 1, wherein the electrode composition further contains nickel-containing particles.   The electrode connection set according to claim 1, wherein the phosphorus-tin-containing copper alloy particles further contain nickel.   The electrode connection set according to any one of claims 1 to 3, wherein the connection material further includes a curing agent and a film forming material.   The electrode connection set according to claim 1, wherein the connection material further contains conductive particles.   The electrode connection set according to claim 1, wherein the electrode composition further contains a dispersion medium. Applying the electrode composition onto a semiconductor substrate having a pn junction;
Heat-treating the semiconductor substrate provided with the electrode composition to form a copper-containing electrode;
Laminating the connection material and the wiring member in this order on the copper-containing electrode, and obtaining a laminate,
A step of heating and pressurizing the laminate,
The manufacturing method of the solar cell which manufactures a solar cell using the electrode connection set of any one of Claims 1-6 containing.   The method for manufacturing a solar cell according to claim 7, wherein the heat treatment is performed at 450 ° C. to 900 ° C.   The solar cell obtained by the manufacturing method of Claim 7 or Claim 8. A solar cell obtained by the manufacturing method according to claim 7 or claim 8,
A sealing material that seals the solar cell so that a part of the wiring member in the solar cell is exposed;
A solar cell module.