JPH06204645A - Ceramic circuit board manufacturing method - Google Patents

Abstract

(57) [Summary] [Structure] A step of applying a conductor paste containing copper particles as a main component onto a ceramic substrate once or a plurality of times, and firing the ceramic substrate coated with the copper conductor paste to form a ceramic substrate on the ceramic substrate. A step of forming a copper conductor layer, a step of polishing the copper conductor layer, and a resist film having a predetermined pattern formed on the copper conductor layer subjected to the polishing treatment, and then an etching treatment to form a circuit. A method of manufacturing a ceramics circuit board, the method including: [Effect] It is possible to form a fine wiring excellent in flatness and adhesiveness on a ceramic circuit board with easy operation and at low cost. Therefore, the obtained ceramic circuit board is extremely useful as a circuit board suitable for multi-chip and high-density mounting of the ceramic circuit board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramics circuit board for mounting semiconductor LSIs, chip parts, etc., and interconnecting them, and more particularly, to a method for manufacturing a ceramics circuit board at low cost. The present invention relates to a method of manufacturing a ceramic circuit board for forming copper fine wiring.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and higher in density, and electronic components mounted on these electronic devices have been rapidly made to have a narrower pitch and a larger number of pins, and have a multi-chip structure. Therefore, as a bonding method for LSIs and IC chips, a TAB (Tape Automated Bonding) method or a flip chip method suitable for multi-chip or high-density mounting has been adopted from the conventional wire bonding method. With the increase in the density of such electronic devices, fine wiring having a line width of 100 μm or less is required for a ceramic wiring board.

Usually, the wiring method on the ceramic substrate is
It is roughly classified into a direct drawing method, a thin film method, a plating method, a thick film printing method and the like.

The above-mentioned direct drawing method is a method for drawing a paste by directly ejecting a paste onto a ceramic substrate from a nozzle, but this method has the problems of low productivity and low flatness of fine wiring.

The thin film method is a method of forming a conductor metal layer of the order of several μm on a ceramic substrate by vacuum vapor deposition, sputtering, ion plating or the like. This method can form thin film fine wiring with high flatness. There are problems that the adhesion to the ceramic substrate is low, when a thin film is formed on a normal ceramic substrate, the irregularities of the wiring become large due to the irregularities of the substrate, and the thin film forming apparatus is expensive.

Further, in order to improve the adhesion with the ceramic substrate, an extra step of roughening the surface of the ceramic substrate is required. Further, in order to eliminate the unevenness of the order of several tens of μm which a normal ceramics substrate has and to flatten it, polishing (lapping) processing must be performed, but polishing the ceramics plate is not easy and takes a lot of time and effort. .

The plating method also has the same problems as the above-mentioned thin film method. Furthermore, since both the thin film method and the plating method form a dense metal conductor layer on the ceramic substrate,
After the heat cycle test, there is a problem that the metal partially peels off from the surface of the ceramic substrate due to a large difference in thermal expansion between the metal and the ceramic, resulting in a marked decrease in adhesion.

[0008]

On the other hand, the thick film printing method is a method in which a conductor paste in which conductor particles are dispersed in an organic vehicle is printed on a ceramics substrate through a mesh screen and baked to be baked on the ceramics substrate. . According to this method, a conductor layer having sufficient adhesion strength with a ceramic substrate can be formed at low cost, but it is unsuitable for forming fine wires of less than 100 μm due to the limit of the wire diameter of the mesh. Further, there is a problem that the surface of the fine wiring formed by the thick film method may have irregularities of several μm order, pinholes or pores. If the surface of the wiring has irregularities of the order of several μm, it is difficult to mount the chip by the TAB method or the flip chip method. In addition, if there are pinholes or pores in the fine wiring, soldering is performed on copper thick film wiring, and if high temperature aging is performed, the solder passes through the pores in the thick film to the bonding interface between the thick film and the ceramic substrate. The phenomenon of diffusion and deterioration of the adhesiveness to the thick film substrate is likely to occur.

For this reason, the fine wiring is ± 1 μm.
In mounting by TAB or flip chip, which requires strict flatness and adhesion to a ceramic substrate as described below, it is difficult to use fine wiring formed by the thick film printing method.

The present invention has been made in view of the above problems, and forms fine wiring having excellent adhesion and high flatness required for mounting by TAB or flip chip with easy operation and at low cost. It is an object of the present invention to provide a method of manufacturing a ceramics circuit board that can be manufactured.

[0011]

In order to achieve the above object, a method of manufacturing a ceramic circuit board according to the present invention (hereinafter referred to as a first method of manufacturing a ceramic circuit board).
Is a step of applying a conductor paste containing copper particles as a main component onto the ceramic substrate once or a plurality of times, and a step of firing the ceramic substrate coated with the copper conductor paste to form a copper conductor layer on the ceramic substrate. And a step of polishing the copper conductor layer, and a step of forming a resist film having a predetermined pattern on the copper conductor layer subjected to the polishing treatment and then performing an etching treatment to form a circuit. Is characterized by.

A method of manufacturing a ceramics circuit board according to the present invention (hereinafter referred to as a second method of manufacturing a ceramics circuit board) comprises a step of applying a conductor paste containing copper particles as a main component on the ceramics substrate. A step of firing a ceramics substrate coated with the copper conductor paste to form a copper conductor layer on the ceramics substrate, a step of forming a resist film having a predetermined pattern on the copper conductor layer, and an etching treatment, and an etching treatment And a step of forming a metal plating layer on the copper conductor layer.

First, the first ceramic circuit board manufacturing method of the present invention will be described in more detail. In the first method for manufacturing a ceramics circuit board, first, a conductor paste containing copper particles as a main component is applied once or plural times onto the ceramics board.

As the ceramic substrate, in addition to the alumina substrate, for example, an aluminum nitride substrate, a glass-ceramic substrate, etc. may be mentioned. The copper conductor paste used in the above step is preferably a conductor paste composed of 100 parts by weight of copper particles having a particle size of 0.5 to 10 μm, 1 to 5 parts by weight of glass particles, and 10 to 20 parts by weight of an organic liquid vehicle. . When the particle size of the copper particles is less than 0.5 μm, the copper powder becomes bulky and the amount of the copper particles in the paste decreases, and when the particle size of the copper particles exceeds 10 μm, the printability of the paste is obtained. Is reduced. The glass particles have a function of adhering the copper conductor layer to the ceramic substrate. When the glass particles are less than 1 part by weight with respect to 100 parts by weight of the copper particles, the adhesion is low, and when the glass particles are more than 5 parts by weight, the copper particles are The wettability of the conductor layer with respect to solder decreases. The organic liquid vehicle is a solvent in which about 3 to 40% by weight of a resin is dissolved in a solvent. When the amount of the organic liquid vehicle is less than 10 parts by weight based on 100 parts by weight of copper particles, the printability of the paste is deteriorated. If it exceeds 20 parts by weight, the burning and burning of the resin in the firing step becomes insufficient. Examples of the resin include ethyl cellulose, acrylic resin, methacrylic resin and the like, and examples of the solvent include terpineol and the like.

As a method of applying the copper conductor paste to the ceramic substrate, a method of solid printing using a normal conductor layer screen is used. Therefore, the coating operation is extremely easy. In the case of applying the coating a plurality of times, after performing solid printing, the coating surface may be left for an appropriate time to level the coating surface, and further dried, and then solid printing may be performed again on the coating surface formed in the above step. Here, the leveling means a step of flattening by leaving the coated surface in a horizontal state, and the leaving time is preferably about 10 minutes. Further, by drying the coated surface, the liquid component in the conductor paste is evaporated and the conductive particles are fixed on the ceramic substrate. The drying condition is usually 120
It is preferable to heat at 10 ° C. for about 10 minutes. The thickness of the coating film formed by the above operation is preferably 20 to 50 μm. When the thickness of the coating film is less than 20 μm, the copper conductor layer on the convex portions of the irregularities due to the warp of the ceramic substrate may disappear due to abrasion in the next polishing step, and the conductor layer of the coating film may be lost. When it exceeds 50 μm, the amount of the conductor paste to be applied becomes too large, which is economically disadvantageous.

Next, the ceramic substrate coated with the copper conductor paste is fired to form a copper conductor layer on the ceramic substrate. The firing conditions are preferably a firing temperature of 600 to 900 ° C. under a nitrogen atmosphere. The conditions for raising the temperature and cooling after firing are not particularly limited as long as they are normal conditions.

Next, the solid thick film made of the copper conductor layer formed on the ceramic substrate in the firing step is polished. The polishing treatment starts with polishing using No. 1500 polishing paper, sequentially using finely-divided polishing paper, and finally performs final polishing using a buff to reduce the thickness of the copper conductor layer. It is performed by polishing until it becomes about 5 μm. By this polishing treatment, the unevenness of the surface of the copper conductor layer is flattened to about ± 0.5 μm or less. The copper conductor layer flattened by the polishing process can be sufficiently mounted on the chip by the TAB method or the flip chip method. Further, this polishing process eliminates pores, pinholes, etc. and densifies the surface layer portion of the copper conductor layer. Therefore, even when high-temperature aging is performed in a state where the surface of the polished copper conductor layer is soldered, the copper conductor layer is densified, so that the solder joins the copper conductor layer and the ceramic substrate. It is possible to prevent the copper conductor layer from adhering to the ceramic substrate from being lowered without penetrating to the interface.

Next, a resist film having a predetermined pattern is formed on the polished copper conductor layer, and then an etching process is performed to form a circuit. The resist film is a known resist film, and is not particularly limited as long as it can withstand a post-etching process. The resist can be applied by using a coating method such as a spin coating method or a roll coating method. Further, the exposure / phenomenon process of the resist film can be performed by a normal process. For example, a contact method or a proximity method can be adopted for the exposure, and development is performed with a predetermined developing solution.

The etching of the copper conductor layer after the development treatment of the resist film is performed by a known method using a known etching solution containing, for example, ferric chloride, cupric chloride or the like as a main component. You can

On the fine copper wiring formed by the above method, a metal such as gold or nickel is deposited for the purpose of preventing oxidation.
You may plate to a thickness of about 5 μm.

By the above-mentioned first method for manufacturing a ceramics circuit board of the present invention, easy operation and low cost,
It is possible to form fine wiring having excellent flatness and adhesiveness on the ceramic circuit board.

Next, a method of manufacturing the second ceramics circuit board of the present invention will be described. Also in the second ceramic circuit board manufacturing method, first, a conductor paste containing copper particles as a main component is applied onto the ceramic board. The ceramic substrate and copper conductor paste used are the same as those used in the first ceramic circuit board manufacturing method. The method of applying the copper conductor paste is also the same as the method of manufacturing the first ceramics circuit board, except that the application is usually performed only once in this method. The thickness of the coating film formed by the above operation is preferably 10 to 20 μm. When the thickness of the coating film is less than 10 μm, pores are likely to occur in the coating film, and when the thickness of the coating film exceeds 20 μm, the unevenness of the surface of the coating film becomes too large, which is not preferable.

Next, the ceramic substrate coated with the copper conductor paste is fired in the same manner as in the first ceramic circuit board manufacturing method to form a copper conductor layer on the ceramic substrate.

Next, after forming a resist film having a predetermined pattern on the formed copper conductor layer, etching treatment is performed. Also in the above-mentioned step, the same step as the step of forming a circuit by etching after forming a resist film having a predetermined pattern on the polished copper conductor layer in the first ceramic circuit board manufacturing method is performed. Methods and conditions can be used. By this step, fine copper wiring is formed.

Next, a metal plating layer is formed on the copper conductor layer on which the fine wiring pattern has been formed by etching. The metal used for forming the plating layer is not particularly limited, but for example, copper or gold is preferable from the viewpoint of conductivity and stability. As a method for forming the plating layer, either an electrolytic plating method or an electroless plating method may be adopted. By this plating process, the unevenness on the surface of the copper conductor layer on the ceramic substrate is flattened to about ± 0.5 μm or less. The copper conductor layer flattened by the plating process enables sufficient mounting of chips by the TAB method and the flip chip method. Furthermore, since the pores and pinholes are eliminated by the plating process and the surface layer portion of the copper conductor layer is densified, even if the surface of the copper conductor layer is subjected to high temperature aging with solder, the solder is It is possible to prevent the adhesive property of the copper conductor layer from adhering to the ceramic substrate from being lowered without penetrating to the bonding interface between the copper conductor layer and the ceramic substrate.

By the second method for manufacturing a ceramics circuit board according to the present invention, the operation is easy and the cost is low.
It is possible to form fine wiring having excellent flatness and adhesiveness on the ceramic circuit board.

[0027]

According to the first method for manufacturing a ceramics circuit board according to the present invention, a step of applying a conductor paste containing copper particles as a main component to the ceramics substrate once or a plurality of times,
A step of firing a ceramics substrate coated with the copper conductor paste to form a copper conductor layer on the ceramics substrate; a step of polishing the copper conductor layer; and a predetermined step on the polished copper conductor layer. Since the step of forming a resist film having a pattern and performing a circuit formation by etching is included, a copper conductor layer having high adhesion to the substrate is formed by applying and firing the copper conductor paste, and the polishing is performed. The difference in unevenness on the surface of the copper conductor layer is about ± 0.5μ depending on the treatment process.
m or less, and since the copper conductor layer is densified by the polishing process, the adhesiveness does not decrease even when soldering.

Further, according to the second method for manufacturing a ceramics circuit board according to the present invention, a step of applying a conductor paste containing copper particles as a main component on the ceramics substrate and a ceramics board applied with the copper conductor paste are provided. A step of firing to form a copper conductor layer on the ceramics substrate, a step of forming a resist film having a predetermined pattern on the copper conductor layer, and an etching treatment, and a step of etching the copper conductor layer with a metal Since it includes a step of forming a plating layer, a copper conductor layer having high adhesion to the substrate is formed by applying and firing the copper conductor paste, and the flatness of the copper conductor layer is about ± The thickness is improved to 0.5 μm or less, and the copper conductor layer is densified by the plating process, so that the adhesiveness does not decrease even when soldering.

[0029]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the method for manufacturing a ceramic circuit board according to the present invention will be described below.

Example 1 100 parts by weight of a copper powder having a particle size of 2 μm, 2 parts by weight of glass frit, and 13 parts by weight of a vehicle in which ethyl cellulose was dissolved in terpineol were kneaded with a three-roll to prepare a conductor paste. Next, the conductor paste was screen-printed on the entire surface of the alumina sintered substrate having a size of 60 mm × 60 mm through a stainless mesh. The difference in surface roughness of this alumina substrate is 10μ
It was m. The printed alumina substrate was subjected to a leveling treatment for 10 minutes and then dried at 120 ° C. for 10 minutes, and then the steps of printing, leveling treatment and drying were repeated again to make the thickness of the printing coating layer 30 μm. The thickness of the coating layer formed on the alumina substrate is measured by a surface roughness meter (Surfcom 112B type, manufactured by Tokyo Seimitsu Co., Ltd.) with reference to the highest convex portion of the unevenness of the substrate.

Next, the alumina substrate on which the coating layer was formed in the above step was heated to 900 ° C. in a nitrogen atmosphere for 30 minutes,
After holding at 900 ° C. for 10 minutes, firing treatment was performed under the condition of cooling to room temperature in 30 minutes. The unevenness of the surface of the copper conductor layer formed by the firing process was about ± 3 μm.

For the surface polishing treatment of the copper conductor layer on the ceramics substrate after firing, first polishing with a No. 1500 polishing paper,
Sequentially, polishing was performed with fine-grained polishing paper, and finally buffing was performed to finish. In this polishing step, the difference between the irregularities on the surface of the copper conductor layer was ± 0.5 μm or less, and the thickness of the copper conductor layer was about 5 μm. In this polishing step, there was no part where the copper conductor layer disappeared due to wear.

A resist film was applied to the copper conductor layer after the polishing treatment by a spin coater, a photomask was brought into contact with the resist film, exposed to light, and developed into a predetermined pattern.

Next, the copper conductor layer is etched with an etching solution containing ferric chloride as a main component to form a predetermined copper wiring pattern, and finally the resist on the copper conductor layer on which a circuit is formed is peeled off. It was removed with liquid. By the above process, a copper fine circuit wiring having a line width of 20 μm could be formed.

The adhesive strength of the copper conductor layer was measured by the following tensile test by the so-called peel method. First, a copper conductor layer was formed on the alumina substrate in the shape of 2 mm × 2 mm square by the above process, and the temperature was maintained at 230 ± 3 ° C. 6
After immersing in a 3% Sn-37% Pb solder bath for 3 ± 0.5 seconds, a 0.6 mmφ tin-plated copper wire was soldered on it with a soldering iron. Next, bend the tin-plated copper wire 90 ° at a position 1 mm from the end of the coating to make it perpendicular to the substrate,
10cm by tensile tester with the substrate fixed
The tin-plated copper wire was pulled at a speed of / min, and the adhesive strength when the tin-plated copper wire was peeled from the substrate was measured and used as the adhesive strength value. The measurement of the adhesive strength was carried out by setting two kinds of conditions immediately after soldering (initial adhesive strength) and after aging at 150 ° C. for 1000 hours (adhesive strength after aging). As a result, the initial adhesive strength is 3
kg / 4mm ² , adhesive strength after aging is 2.7kg / 4mm
^A value as high as ² was obtained.

[Comparative Example 1] Similar to Example 1 except that a ceramics substrate coated with a copper conductor paste was fired to form a copper conductor layer on the ceramics substrate, and then the copper conductor layer was not polished. When copper fine wiring was formed by carrying out the method of No. 3, the roughness of the copper conductor layer surface layer was as rough as ± 3 μm,
The adhesive strength after aging was as low as 0.5 kg / 4 mm ² .

[Example 2] The same alumina sintered substrate as in Example 1 was used, and the conductor paste was screen-printed on the entire surface of the substrate in the same manner as in Example 1. The difference in the unevenness on the surface of the alumina substrate was 10 μm. The alumina substrate after printing the conductor paste is leveled for 10 minutes and then at 120 ° C.
And dried for 10 minutes. The thickness of the print coating layer was 10 μm.

Next, the alumina substrate on which the coating layer was formed in the above step was subjected to a firing treatment in the same manner as in Example 1,
The difference in unevenness on the surface of the formed copper conductor layer was about ± 3 μm.

A method of forming a circuit having a predetermined pattern by etching the copper conductor layer on the ceramic substrate after firing was also carried out in the same manner as in Example 1. By this process, a copper fine wiring having a line width of 20 μm could be formed.

Next, a new copper conductor layer having a thickness of 3 μm was formed on the copper fine wiring by electrolytic plating. The electrolytic plating is CuSO ₄ .5H ₂ O 75 g / L and concentrated sulfuric acid 1
70 g / L, 60 ppm of chlorine ions, and a plating solution containing a brightening agent, current density of 1.5 A / d
It was conducted under the conditions of m ² and an energization time of 30 minutes.

The unevenness of the surface of the copper fine wiring made of the plated copper conductor layer was ± 0.5 μm or less, which was extremely flat.

In addition, the adhesive strength of the above-mentioned copper wiring was measured according to the first embodiment.
In the same manner as above, the tensile test was performed by the peel method. As a result, initial adhesive strength is 3 kg / 4 mm ^2, the adhesive strength after aging was obtained as high as 2.7 kg / 4 mm ^2.

[Comparative Example 2] A fine copper wiring was formed in the same manner as in Example 2 except that the plating treatment was not performed. The surface roughness of the copper conductor layer was as rough as ± 3 μm. Also had a low adhesive strength of 0.5 kg / 4 mm ² .

[0044]

As described above in detail, in the first method for manufacturing a ceramic circuit board according to the present invention, the conductive paste containing copper particles as a main component is applied to the ceramic board once or plural times. A step, a step of firing a ceramic substrate coated with the copper conductor paste to form a copper conductor layer on the ceramic substrate, a step of polishing the copper conductor layer, and the copper conductor layer subjected to the polishing treatment Since it includes a step of forming a circuit film by etching after forming a resist film having a predetermined pattern on the ceramic circuit board, it has excellent flatness and adhesiveness at easy operation and low cost. Fine wiring can be formed.

Further, in the second method for manufacturing a ceramic circuit board according to the present invention, a step of applying a conductor paste containing copper particles as a main component on the ceramic substrate, and a ceramic board applied with the copper conductor paste To form a copper conductor layer on the ceramics substrate by firing, a step of forming a resist film having a predetermined pattern on the copper conductor layer, and then performing an etching process, and the etching of the copper conductor layer. Since it includes a step of forming a metal plating layer, fine wiring excellent in flatness and adhesiveness can be formed on a ceramic circuit board with the same easy operation and low cost as in the first ceramic substrate manufacturing method. Can be formed.

Therefore, the ceramic circuit board obtained by the above two manufacturing methods according to the present invention is very useful as a circuit board suitable for multi-chip and high-density mounting of the ceramic circuit board.

Claims (2)

[Claims] 1. A step of applying a conductor paste containing copper particles as a main component onto a ceramic substrate once or a plurality of times, and firing the ceramic substrate coated with the copper conductor paste to form a copper conductor layer on the ceramic substrate. A step of forming, a step of polishing the copper conductor layer, and a step of forming a resist film having a predetermined pattern on the polished copper conductor layer and then performing an etching process to form a circuit. A method for manufacturing a ceramics circuit board, characterized by being formed. 2. A step of applying a conductor paste containing copper particles as a main component on a ceramic substrate, and a step of firing the ceramic substrate coated with the copper conductor paste to form a copper conductor layer on the ceramic substrate. It is characterized by including a step of forming a resist film having a predetermined pattern on the copper conductor layer, and then performing an etching treatment, and a step of forming a metal plating layer on the etched copper conductor layer. Manufacturing method of ceramics circuit board.