JP4984431B2 - Integrated thin film solar cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to an integrated thin film solar cell and a method for manufacturing the same, and particularly relates to an integrated thin film solar cell having a low environmental load and excellent appearance, reliability, and productivity, and a method for manufacturing the same. Is.

  Conventionally, eutectic solders composed of tin and lead have been widely used as solders used in electronic products such as home appliances and electronic devices. It is recognized that the lead component has a great environmental impact, including effects on the human body, and its use has been regulated. There is an urgent need to develop a solder containing no lead component or having a small lead component composition (hereinafter referred to as lead-free solder). For example, Patent Document 1 discloses that Ag is 3 to 5% by weight and Cu is 0%. A lead-free solder having a composition of 0.5 to 3% by weight, Sb of 0 to 5% by weight, and the balance of Sn is described.

In addition, as disclosed in Patent Document 2, the use of lead-free solder has also been studied in the field of solar cells.
JP-A-5-50289 JP 2002-314104 A

  However, it is an integrated thin film solar cell in which a plurality of cells composed of solar cell layers directly formed on a glass substrate are integrated, and the positive and negative electrode portions having the largest potential difference in the integrated thin film solar cell In an integrated thin film solar cell in which solder bumps are formed in a row at predetermined intervals in a lead attachment area where a lead wire is attached as an extraction electrode, and a solder dip lead wire is attached as an extraction electrode, solder An integrated thin film solar cell using lead-free solder with satisfactory reliability and productivity has not been obtained due to differences in the composition of the solder of the bump and the solder forming the solder dip lead wire, etc. .

  In general, lead-free ceramic solder has a higher melting point than solder containing conventional lead components, and in particular, an integrated thin film solar cell in which a plurality of cells composed of solar cell layers directly formed on a glass substrate are integrated. When forming a solder bump on the film surface of the solar cell layer, the transparent conductive oxide layer, or the glass surface, a solder that can be firmly soldered to such a metal oxide, for example, is required. When the solder dip lead wire is attached to the solder bump, the solder dip lead wire is held in a molten state for a longer time than necessary until the solder bump is melted. There is a problem that the bonding strength between the solder bump and the solder bump is insufficient.

  However, if the melting point of the solder of the solder dip lead wire is higher than the melting point of the solder of the bump solder, the solder of the solder bump is held in a molten state for an unnecessarily long time until the solder of the solder dip lead wire is melted. For example, there is a problem that the solder deteriorates due to oxidation or the like, and the mechanical strength of the joint portion between the solder bump and the film surface of the solar cell layer, the transparent conductive oxide layer, or the glass surface decreases.

  The integrated thin film solar cell of the present invention is an integrated thin film solar cell in which a plurality of cells each formed of a solar cell layer directly formed on a glass substrate are integrated, and is the most in the integrated thin film solar cell. In positive and negative electrode portions where the potential difference increases, a plurality of solder dip lead wires corresponding to each of the electrode portions as a take-out electrode are provided on the glass substrate at predetermined intervals within the one electrode portion. The solder dip lead wire and the solder composition of the solder bump are respectively Ag, Al, Cu, Zn, Sb, In, Ge, P, and Ni. Integrated thin-film solar comprising 0.05% by weight or more and 11% by weight or less of at least one element selected from Bi, and Sn containing 89% by weight or more and 99.5% or less by weight A pond, electrode lead be used lead-free solder can be formed with high mechanical strength on a glass substrate.

  It is preferable that the difference between the solder melting point of the solder bump and the solder melting point of the solder dip lead wire is 20 ° C. or less because the mechanical strength is particularly high. More preferably, it is 14 degrees C or less.

  The solder of the solder dip lead wire preferably contains Sn as a main component, contains 2.5 to 7.7% by weight of Ag, and contains 0.0 to 4.0% by weight of Cu. As solder of the solder bump, Sn is a main component, Zn is 2.5 to 4.0% by weight, Sb is 0.5 to 3.0% by weight, and Al is 0.02 to 0.1% by weight. It is preferable that it is included.

  Most preferably, the melting point of the solder dip lead wire is about 10 ° C. lower than the melting point of the bump solder solder. When soldering in this state, the solder dip lead wire melts. At the same time, since the amount of heat of the soldering iron easily moves to the solder bumps through the solder dip lead wires, the solder dip lead wires and the solder bumps melt almost simultaneously, and the solder dip lead wires, the solder bumps, and the solar cell Three members, such as a film surface of a layer, a transparent conductive oxide layer, or a glass surface, can be bonded particularly firmly.

  Furthermore, as a manufacturing method of the integrated thin film solar cell of the present invention, a step of forming a plurality of solder bumps on the glass substrate in advance before the soldering, and the solder dip lead wires at 40 to 150 ° C. Heating and then soldering the soldering iron from the side of the solder dip lead wire to include the step of soldering will reduce the rate at which the amount of heat transmitted from the soldering iron diffuses on the solder dip lead wire. Therefore, the melting of the solder dip lead wire and the solder bump is likely to occur almost at the same time. Therefore, the solder dip lead wire, the solder bump, the film surface of the solar cell layer, the transparent conductive oxide layer, the glass surface, etc. Is preferable because it can be more firmly joined.

  In integrated thin-film solar cells in which solder bumps are formed in rows at predetermined intervals in the lead attachment area and solder dip lead wires are attached, especially the bump solder and the solar cell layer film surface, transparent conductive oxidation An integrated thin-film solar cell using lead-free solder that can satisfy the mechanical strength of the solar cell junction such as a physical layer or a glass surface can be obtained.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In the drawings of the present application, the same reference numerals indicate the same or corresponding parts, and redundant description is not repeated.

  FIG. 1 is an explanatory view for explaining an integrated thin film solar cell 1 of the present invention. As shown in FIG. 1, the integrated thin-film solar cell 1 is provided on a glass substrate 2 with a region 3 in which photoelectric conversion cells composed of solar cell layers that convert light into electric power are integrated, and on the glass substrate 2 side. The light incident from the light is photoelectrically converted by the photoelectric conversion cell. Insulation from the surroundings is achieved by the insulating wire 4 and the power generated through the solder dip lead wire 5 is taken out.

  Further, FIG. 2 shows a part of the structure in the cross-sectional direction of line A in FIG. As shown in FIG. 2, the integrated thin film solar cell 1 includes a structure in which a transparent conductive film 6, a photoelectric conversion film 7, and a back electrode film 8 are sequentially laminated on a glass substrate 2, and solder for taking out generated power. A solder bump 9 for connecting the dip lead wire 5 to the transparent conductive film 6, the photoelectric conversion film 7, and / or the back electrode film 8 is provided.

  Next, each component of the thin film solar cell 1 will be described.

As the glass substrate 2, it is possible to use a float plate glass which has a large area plate available at low cost, is highly transparent and has high insulating properties, and has both main surfaces of which are mainly composed of SiO ₂ , Na ₂ O and CaO. .

The transparent conductive film 6 can be composed of a transparent conductive oxide layer such as an ITO film, a SnO ₂ film, or a ZnO film. The transparent conductive film 6 can be formed using a known vapor deposition method such as an evaporation method, a CVD method, or a sputtering method.

  The photoelectric conversion film 7 includes an amorphous and / or polycrystalline silicon-based semiconductor photoelectric conversion layer. For example, a p-type silicon-based semiconductor layer, an i-type silicon-based semiconductor layer, and an n-type silicon are formed from the transparent conductive film 6 side. It has a structure in which system-based semiconductor layers are sequentially stacked. These p-type semiconductor layer, i-type semiconductor layer, and n-type semiconductor layer can all be formed by a plasma CVD method. Moreover, a tandem structure in which these pin structures are stacked in two stages, a triple structure in which three stages are stacked, or the like may be used.

  The p-type semiconductor layer constituting the photoelectric conversion film 7 can be formed, for example, by doping silicon or a silicon alloy such as silicon carbide or silicon germanium with p conductivity type determining impurity atoms such as boron or aluminum. The i-type semiconductor layer can be formed of an amorphous silicon-based semiconductor material and a crystalline silicon-based semiconductor material, respectively. Examples of such a material include intrinsic semiconductor silicon (such as silicon hydride) and silicon carbide. In addition, silicon alloys such as silicon germanium can be fisted. In addition, if the photoelectric conversion function is sufficiently provided, a weak p-type or weak n-type silicon-based semiconductor material containing a small amount of a conductivity type determining impurity may be used. Furthermore, the n-type semiconductor layer can be formed by doping silicon or a silicon alloy such as silicon carbide or silicon germanium with n-conductivity determining impurity atoms such as phosphorus or nitrogen.

  The back electrode film 8 not only has a function as an electrode, but also reflects light that enters the photoelectric conversion film 7 from the insulating translucent substrate 2 and arrives at the back electrode film 8 and re-enters the photoelectric conversion film 7. It also functions as a layer. The back electrode film 8 can be formed to a thickness of, for example, about 200 nm to 400 nm by vapor deposition, sputtering, or the like using silver, aluminum, or the like.

  A transparent conductive thin film (not shown) made of a nonmetallic material such as ZnO is provided between the back electrode film 8 and the photoelectric conversion film 7, for example, in order to improve the adhesion between them. be able to.

  The solder dip lead 5 includes at least one element selected from Ag, Al, Cu, Zn, Sb, In, Ge, P, Ni, and Bi, and melts a solder having a composition of Sn 89% by weight or more. It can be produced by immersing a copper foil in the object and coating the surface of the copper foil with solder.

  Examples of the solder include a solder having a composition of Ag 2.5 to 7.7 wt%, Cu 0.0 to 4.0 wt%, Sn 89 wt% or more, Zn 1.0 to 11 wt%, and Sn 89 wt% or more. Solder made of can be used. More preferably, the solder is composed of Ag 2.5 to 4.0% by weight, Cu 0.0 to 1.5% by weight, and Sn 89% by weight or more.

  The thickness of the copper foil is preferably 40 μm to 120 μm, and more preferably 60 μm to 100 μm. The thickness of the solder coated on the surface of the copper foil is preferably 10 μm to 80 μm, and more preferably 20 μm to 60 μm. Further, Pb contained in these solder compositions is 0.1% by weight or less, preferably 0.05% by weight or less in consideration of manufacturing cost. When the melting point of the solder of the solder dip lead wire 5 is higher than 250 ° C., the solder lead wire needs to be attached at a temperature higher than 350 ° C., the solder iron is contaminated due to solder oxidation, and the solar cell element is damaged due to heating. Is greatly accelerated. Considering the cost balance, the Sn weight composition is preferably 89% by weight or more.

  The solder bump 9 is a ceramic solder that can be soldered to a metal oxide because it needs to be physically firmly fixed and electrically connected to the transparent conductive film 6 that is a transparent conductive oxide layer. Therefore, the solder contains at least one element selected from Ag, Al, Cu, Sb, In, Ge, P, Ni, and Bi, and the total composition of Sn and Zn is 89% by weight or more. Examples of the solder include a solder having a composition of Ag 2.5 to 7.7 wt%, Cu 0.0 to 4.0 wt%, Sn 89 wt% or more, Zn 1.0 to 11 wt%, and Sn 89 wt% or more. Solder made of can be used. More preferably, the solder is composed of Ag 2.5 to 4.0% by weight, Cu 0.0 to 1.5% by weight, and Sn 89% by weight or more. When the melting point of the solder bump 9 is higher than 250 ° C., the solder bump 9 needs to be formed at a temperature higher than 350 ° C., and the contamination of the small tip due to the oxidation of the solder and the damage to the solar cell element due to the heating are greatly accelerated. The In consideration of cost balance, the Sn weight composition is preferably 89% by weight or more.

  Further, Pb contained in these solder compositions is 2% by weight or less in consideration of manufacturing cost. Preferably, it is 1% by weight or less. Although addition of a flux is possible, in order to ensure the reliability in the long-term use of a thin film solar cell, it is preferable not to contain a flux.

  First, after forming the transparent conductive film 6 on the entire surface of one side of the glass substrate 2, the first separation groove 10 that divides the transparent conductive film 6 into strips is formed by, for example, irradiating YAG fundamental wave laser light.

  Next, amorphous silicon and / or polycrystalline silicon as the photoelectric conversion film 7 is formed once in the order of p-type, i-type, and n-type by the plasma CVD method over the transparent conductive film 6 in which the first separation groove 10 is formed. After the above lamination, for example, YAG second harmonic laser light is irradiated to form connection grooves 11 that divide the photoelectric conversion film 7 into strips.

  Subsequently, after forming a transparent conductive thin film and a metal film as a back electrode film 8 over the photoelectric conversion film 7 in which the connection groove 11 is formed by a sputtering method or the like in this order, for example, YAG second harmonic laser light is insulated and transmitted. A second separation groove 12 that irradiates from the optical substrate 2 side and divides the back electrode film 8 into strips is formed. In this way, the transparent conductive film 6, the photoelectric conversion film 7 made of an amorphous and / or polycrystalline silicon-based semiconductor, and the back electrode film 8 are sequentially stacked on one main surface of the insulating translucent substrate 2. A cell region 3 including a multilayer film and including a plurality of photoelectric conversion cells connected in series is formed.

  Furthermore, the solder dip lead wires 5 for taking out electric power are formed on the positive and negative electrode portions having the largest potential difference in the integrated thin film solar cell 1, and usually on both sides of the glass substrate outside the integrated solar cell layer. Place it in a close area. For example, the YAG second harmonic laser beam is irradiated from the side of the insulating translucent substrate 2 to the outer ends of both ends of the plurality of integrated photoelectric conversion cells indicated by the broken lines B and C in FIG. The conversion film 7 and the back electrode film 8 are removed, and lead connection grooves 13 having the shape shown in FIG. 4 are formed. As shown in FIG. 5, a solder bank 9 is formed from the photoelectric conversion cell side so as to overlap with the connection groove 13. The shape of this solder bank is fixed to the transparent electrode layer 6 as shown in FIG. 6, fills the connection groove 13, and protrudes from the photoelectric conversion cell. In this formed solder bank 9, a solder dip lead wire 5 is attached using a heated soldering iron, and as shown in FIG. Battery 1 can be produced.

  The first method for producing the solder dip lead wire 9 for taking out the power is, for example, an ultrasonic vibrator and a soldering iron (hereinafter referred to as an ultrasonic solder) directly connected to the ultrasonic vibrator and having an electric heater inside. Is used). That is, in the ultrasonic soldering iron, the solder used for the solder bumps 9 is melted and adhered and held on the ultrasonic soldering iron, and the vibration generated by the ultrasonic vibrator is transmitted to the ultrasonic soldering iron. Then, the solder bumps 9 are formed by pressing against the connection grooves 13. In this case, the temperature of the heated ultrasonic soldering iron is in the range of 20 ° C. to 300 ° C. higher than the melting point of the ceramic solder used for the solder bump 9 (showing the liquid phase temperature when the liquid phase temperature and the solid phase temperature are present). It is. It is preferable that it is 40 to 150 degreeC. When the temperature of the ultrasonic soldering iron is close to the melting point of the ceramic solder used for the solder bump 9, the melting rate of the ceramic solder is slow and the productivity is lowered. On the other hand, if the temperature of the ultrasonic soldering iron is too high, the oxidation of the ceramic solder proceeds and the quality is impaired.

  As a second stage, a soldering iron heated by an electric heater (hereinafter referred to as a soldering iron for lead wires) is pressed from the solder dip lead wire 5 side to be melted and connected to the solder bumps 9. In this case, the temperature of the lead wire soldering iron is in the range of 20 ° C. to 300 ° C. higher than the melting point of the solder used for the solder dip lead wire 5. It is preferable that it is 40 to 150 degreeC. If the temperature of the soldering iron for the lead wire is close to the melting point of the solder used for the solder dip lead wire 5, the melting rate of the solder is slow and the productivity is lowered. On the other hand, if the temperature of the lead wire soldering iron is too high, the solder oxidizes and the quality is impaired.

  When the melting point of the solder forming the solder bump 9 and the solder used for the solder dip lead 5 is greatly different, the previously melted solder wets and spreads on the solder dip lead 5 due to surface tension, and is lost from the joint portion. The bonding strength of the dip lead wire 5 is reduced. In order to match the timing of melting of the solder, the difference in melting point between the ceramic solder used for the solder bank 9 and the solder used for the solder dip lead 5 is preferably 50 ° C. or less, more preferably 20 ° C. or less, and still more preferably. It is 14 degrees C or less. This is because, when the solder dip lead wire 5 is attached to the solder bump 9, the machine of the joint portion between the solder bump 9 and the transparent electrode layer 6 that is generated when the solder bump 9 is held in a molten state for an unnecessarily long time. This is because a decrease in strength can be suppressed. Furthermore, the melting point of the ceramic solder used for the solder bump 9 is preferably higher than that of the solder used for the solder dip lead wire 5.

  Further, in the step of attaching the solder dip lead wire 5 to the solder bump 9 by a lead wire soldering iron, once the solder bump 9 formed on the transparent electrode 9 is held in a molten state at a high temperature for a long time, The bond between the bump 9 and the transparent electrode film 6 is broken, and the bonding force is reduced. Compared with conventional Sn—Pb eutectic solder, lead-free solder has a higher melting point, and therefore the temperature range in which the solder dip lead wire 5 can be attached becomes smaller. Therefore, under the one-stage heating condition of the solder dip lead 5, there is a possibility that a mounting failure may occur, and a multi-stage heating process is advantageous. That is, after heating the entire thin film solar cell 1 or a part thereof, the solder dip lead wire 5 is attached to the solder bump 9 by a lead wire soldering iron. In this case, the entire thin film solar cell 1 may be heated, the lead attachment portion including the solder bump 9 may be heated, or the solder dip lead wire 5 may be heated. Preferably, the solder dip lead wire 5 is heated. The heating temperature is preferably 40 to 150 ° C, more preferably 100 to 150 ° C. In addition, the number of heating steps is preferably 2 to 5 in consideration of the apparatus cost. More preferably, it is 2-3 steps.

  In this way, the integrated thin film solar cell 1 provided with the solder dip lead 5 for taking out electric power is formed.

  The thin film solar cell 1 used in an outdoor environment seals a protective film from the photoelectric conversion cell side for the purpose of protecting it. The protective film is firmly adhered to the thin-film solar cell through a sealing resin that can be cured through heating and softening / melting. Examples of such a protective film include a fluororesin film such as a polyvinyl fluoride film (for example, Tedlar film (registered trademark)), an organic film such as a polyethylene terephthalate (PET) film, and a metal foil made of aluminum or the like. A laminated film having a structure laminated in a single layer structure or a multilayer structure. Examples of the sealing resin that can be cured through heating and softening / melting include, for example, ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyrate (PVB). A crosslinking agent such as a peroxide compound is added to a thermoplastic resin such as polyisobutylene (PIB).

  Moreover, when attaching a protective film to the integrated thin film solar cell 1 in this way, the solder dip for taking out the electric power through the internal wiring using the solder dip copper foil, metal foil, cable, etc. and the external wiring agent such as the terminal box The electric power obtained from the lead wire is taken out. Moreover, when using a solder material for the internal wiring agent, it is preferable to use lead-free solder.

  Hereinafter, although the present invention is explained in detail based on some examples, the present invention is not limited to the following description examples unless it exceeds the purpose.

  A thin film solar cell 1 was produced according to the above-described embodiment.

First, on a glass substrate 2 having an area of 980 mm × 950 mm and a thickness of 5 mm, an SnO ₂ film having a thickness of about 700 nm was formed as a transparent conductive film 6 by a thermal CVD method. By irradiating the SnO ₂ film 6 with a YAG fundamental wave laser beam from the SnO ₂ film 6 side, a first separation groove 10 was formed by patterning.

  Next, after fine powders and the like generated by the processing were washed away, the glass substrate 2 was carried into a plasma CVD film forming apparatus, and a photoelectric conversion film 7 made of amorphous silicon having a thickness of about 300 nm was formed. After unloading the glass substrate 2 from the CVD apparatus, the connecting groove 11 was formed by irradiating the photoelectric conversion film 7 with YAG second harmonic laser light from the glass substrate 2 side.

Next, as a back electrode film 8, a ZnO film having a thickness of about 80 nm and an Ag film having a thickness of about 300 nm were formed on the photoelectric conversion film 7 in this order by a sputtering method. Furthermore, the back electrode film 8 was irradiated with YAG second harmonic laser light from the glass substrate 2 side, and divided into strips to form second separation grooves 12. In order to insulate the cell region and the connection region from the periphery of the glass substrate 2, YAG laser light is irradiated along the periphery of the glass substrate 2, and the SnO ₂ film 6, the amorphous silicon photoelectric conversion film 7, and the back electrode film 8. Then, the insulating wire 4 was formed. As described above, an integrated thin film solar cell in which 108 photoelectric conversion cells having an area of approximately 82.67 cm ² were connected in series was obtained.

  Next, as the solder of the solder bump 9, those having the composition of H1, H2, and H3 shown in Table 1 and the melting temperature are used, the diameter of the solder melt adhesion portion (tip) is 1 mm, and the ultrasonic soldering iron is set to a temperature of 300. Forty-six solder banks were formed in the solder connection grooves 13 at 20 mm intervals at a temperature of 3 ° C., an ultrasonic output of 3 W, and a soldering time of 1 s. The formed solder bank had a diameter of 2.0 to 2.7 mm and a height of 0.2 to 0.5 mm.

次に、リード線用半田コテを用いて、半田ディップリード線５と半田バンプ９を溶融・接続した。表２に使用した半田ディップリード線５であるＬ１、Ｌ２、Ｌ３、及びＬ４の半田の組成、及び融点を示す。また、半田ディップリード線を構成する銅箔の厚みは８０μｍ、幅２ｍｍとした。

Next, the solder dip lead wire 5 and the solder bump 9 were melted and connected using a lead wire soldering iron. Table 2 shows the solder composition and melting point of L1, L2, L3, and L4, which are the solder dip lead wires 5 used. The thickness of the copper foil constituting the solder dip lead wire was 80 μm and the width was 2 mm.

ここで、リード用半田コテの温度を半田ディップリード線の融点から凡そ４０〜１６０℃の範囲で２０℃毎に変化させて接続した。つまり２４０℃から３６０℃の範囲で７つの温度で、表１の半田バンプ３組成、及び表２の半田ディップコートの４半田組成の、７×３×４通り＝８４通りの組み合わせにつき集積型薄膜太陽電池１を作成した。

Here, the temperature of the lead soldering iron was changed every 20 ° C. within the range of 40 to 160 ° C. from the melting point of the solder dip lead wire, and the connection was made. That is, the integrated thin film per 7 × 3 × 4 = 84 combinations of the solder bump 3 composition in Table 1 and the four solder compositions in Table 2 at 7 temperatures in the range of 240 ° C. to 360 ° C. A solar cell 1 was prepared.

  Finally, the 90 ° tensile strength (tensile speed 1 mm / 1 s) of the solder dip lead wire 5 soldered onto the glass substrate 2 via the solder bumps 9 was measured. The results are shown in Table 3. The tensile strength values in the table are 46 points / average value.

表３に示すように、半田ディップリード線の９０°引っ張り強度は、リード線用半田コテの温度が半田ディップリード線の半田の融点より凡そ１００℃高い温度領域で最大となり、また、その最大の値は、表３の実験結果に示すように、半田バンプ９の半田と半田ディップリード線５の半田の融点が近いほど大きくなる傾向を示した。特に、図９に示すように、半田バンプ９の半田と半田ディップリード線５の半田の融点の差（絶対値）が２０℃より小さくなる方向で、半田ディップリード線５の９０°引っ張り強度の最大値は増大する傾向を示した。

As shown in Table 3, the 90 ° tensile strength of the solder dip lead wire is maximum in the temperature region where the temperature of the soldering iron for the lead wire is approximately 100 ° C. higher than the melting point of the solder of the solder dip lead wire, and the maximum As shown in the experimental results of Table 3, the values tended to increase as the melting points of the solder bump 9 and the solder dip lead 5 became closer. In particular, as shown in FIG. 9, the 90 ° tensile strength of the solder dip lead wire 5 is such that the difference (absolute value) in melting point between the solder of the solder bump 9 and the solder of the solder dip lead wire 5 becomes smaller than 20 ° C. The maximum value tended to increase.

  Also, in Table 4, when the solder dip lead wire 5 is mounted at the same temperature after the solder dip lead wire 5 is heated to 120 ° C. and the solder dip lead wire 5 is set at 320 ° C. in the lead soldering iron of Example 1 in Table 3 Of non-defective products was shown (the solder unmelted / non-bonded one was regarded as defective). Heating was performed with a hot air heater. As shown in Table 4, it was found that by attaching the solder dip lead wire 5 to the solder bump 9 after heating the solder dip lead wire 5, the non-defective product rate of the attachment was improved.

The conceptual diagram explaining the integrated thin film solar cell of this invention notionally The conceptual diagram explaining notionally the cross section of the integrated thin film solar cell of this invention The top view which shows one processing example of this invention notionally Sectional drawing which shows one processing example of this invention notionally The top view which shows one processing example of this invention notionally Sectional drawing which shows one processing example of this invention notionally Sectional drawing which shows one processing example of this invention notionally The figure explaining the experimental result of the relationship between the difference in the melting point of the solder between the solder bump and the solder dip lead and the adhesion of the solder dip lead to the glass substrate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Integrated thin-film solar cell 2 Glass substrate 3 The area | region where the photoelectric conversion cell is integrated 4 Insulation wire 5 Solder dip lead wire 6 Transparent conductive film 7 Photoelectric conversion film 8 Back surface electrode film 9 Solder bump 10 First separation groove 11 Connection groove 12 Second separation groove 13 Lead connection groove

Claims (3)

An integrated thin film solar cell in which a plurality of cells composed of a solar cell layer directly formed on a glass substrate are integrated, and the positive and negative electrode portions in the integrated thin film solar cell have the largest potential difference. A solder dip lead wire as an extraction electrode corresponding to each of the electrode portions is disposed on the glass substrate at a plurality of positions at a predetermined interval in one electrode portion via solder bumps. it is soldered, the solder of the solder dipping leads, as a main component Sn, and Ag 2.5-7.7 wt%, and lead composition comprising a Cu .0 to 4.0 wt% The solder of the solder bump is composed of Sn as a main component, Zn is 2.5 to 4.0 wt%, Sb is 0.5 to 3.0 wt%, and Al is 0.02 to 0.02 wt%. It is a lead-free solder composition comprising 0.1% by weight, the solder vans And the melting point of the solder of the difference in the melting point of the solder of the solder dipping leads, integrated thin-film solar cell, characterized in that at 20 ° C. or less.   2. The integrated thin-film solar cell according to claim 1, wherein a difference between a melting point of the solder of the solder bump and a melting point of the solder of the solder dip lead wire is 14 ° C. or less. 3. The method of manufacturing an integrated thin film solar cell according to claim 1, wherein a plurality of solder bumps are formed on the glass substrate in advance before the soldering, and the solder is formed at 40 to 150 ° C. A method of manufacturing an integrated thin film solar cell, comprising the step of heating the dip lead wire and then performing the soldering by pressing a soldering iron from the solder dip lead wire side.

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