JPH06224538A - Manufacture of ceramic circuit board - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a fine copper wiring with advantages in density, adhesiveness, and flatness with easy operation at low cost, by oxidizing copper powder of a coating layer in heat treatment, reducing the oxidized copper, and sintering the copper in a neutral atmosphere. CONSTITUTION:A ceramic board is coated with a photo-damping conductive material that is mainly made of copper powder, glass powder, and a photosensitive resin in a coating step. A coating layer formed in the coating step is exposed and developed to form a given wiring pattern in a development step. Then, the ceramic board is treated by heat in an oxidizing atmosphere at a temperature enough to decompose and scatter an organic material like the photosensitive material in the coating layer. The copper-oxide powder of the coated layer, which is oxidized in a heat treatment step, is reduced in a reduction step and sintered in a neutral atmosphere in a burning step. In this way, a fine copper wiring with advantages in density, adhesiveness, and flatness on the ceramic circuit board can be produced at low cost with easy operation.

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.

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 ceramic substrate through a mesh screen and baked to burn the ceramic substrate. This method can form a conductor layer having sufficient adhesion strength with a ceramic substrate at a low cost, but has a problem that it is difficult to form fine wiring of less than 100 μm due to the limit of the wire diameter of the mesh. There is.

Therefore, there has been attempted a method in which the thick film printing method is basically used and a photolithography method, which is a characteristic of the thin film method, is introduced for forming a wiring pattern. The method will be described below. First, a conductive powder is prepared by dispersing a conductive powder in a photosensitive liquid formed by dissolving a photosensitive resin composed of a photocurable monomer in a solvent to prepare a photosensitive conductor paste. The paste is solid-printed on a ceramic substrate by a thick film printing method, and exposed and developed to form a predetermined pattern. Next, the photocurable resin cured by firing the ceramic substrate on which the predetermined pattern is formed is decomposed and scattered (debinding), and at the same time, the conductive film is baked on the ceramic substrate to complete the formation of the copper fine wiring. .

[0010]

In the above method, the amount of the photosensitive resin in the photosensitive conductor paste is considerably larger than the amount of the resin in the normal thick film conductor paste. This is because when the amount of photosensitive resin in the photosensitive conductor paste is small, the amount of conductive powder in the photosensitive conductor paste is relatively large,
Since the ultraviolet rays irradiated in the exposure step are blocked by the conductive powder and the ultraviolet rays are not sufficiently transmitted in the thickness direction of the thick film applied, the photosensitive resin is not sufficiently exposed and it is difficult to develop. is there.

However, since a large amount of the photosensitive resin is present in the photosensitive conductor paste and the photosensitive resin hardened in the developing step is less likely to burn, the resin hardened in the debinding step is sufficient. There is a problem that they remain without being decomposed and scattered, hindering the sintering of the conductor powder and reducing the adhesive strength of the formed wiring to the ceramic substrate. In particular, when copper powder is used as the conductive powder, usually, since the firing was carried out in a reducing atmosphere such as a nitrogen atmosphere in order to prevent the oxidation of the copper powder, further decomposition and scattering of the photosensitive resin, etc. was difficult.

Furthermore, since a large amount of the photosensitive resin is present in the photosensitive conductor paste, the concentration of the conductive powder in the photosensitive conductor paste becomes low, and even after the photosensitive resin is removed, the conductivity in the wiring pattern is reduced. There is also a problem that the degree of filling of the conductive powder becomes low and a sufficiently densified wiring cannot be obtained by firing.

The present invention has been made in view of the above problems, and provides fine wiring having excellent compactness and adhesiveness and high flatness.
It is an object of the present invention to provide a method for manufacturing a ceramics circuit board that can be formed easily and at low cost.

[0014]

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 coating step of coating a copper substrate, a glass powder, and a photosensitive conductor paste containing a photosensitive resin as a main component on a ceramic substrate, and the coating layer formed by the coating step is exposed and developed in a predetermined wiring pattern. A development treatment step; a step of heat-treating the ceramic substrate subjected to the development treatment in an oxidizing atmosphere at a temperature at which the photosensitive resin in the coating layer decomposes and scatters; and a coating layer oxidized in the heat treatment step It is characterized in that it includes a reduction treatment step of reducing the copper powder and a firing step of sintering copper in a neutral atmosphere.

The method of manufacturing a ceramics circuit board according to the present invention (hereinafter referred to as the second method of manufacturing a ceramics circuit board) includes a photosensitive material containing copper powder, glass powder and a photosensitive resin as main components on the ceramics substrate. Of applying a conductive conductor paste, a developing step of exposing and developing the coating layer formed by the applying step to a predetermined wiring pattern, and the ceramic substrate subjected to the developing step under an oxidizing atmosphere. It includes a step of heat treatment at a temperature at which the photosensitive resin in the coating layer decomposes and scatters, and a reduction firing step of reducing and sintering the copper powder in the coating layer oxidized in the heat treatment step. It has a feature.

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 ceramic circuit board, first, as a coating step, a step of coating a photosensitive conductor paste containing copper powder, glass powder and a photosensitive resin as a main component on the ceramic substrate is carried out.

As the ceramic substrate, in addition to the alumina substrate, for example, an aluminum nitride substrate, a glass-ceramic substrate and the like can be mentioned. The photosensitive conductor paste used in the coating step contains 100 parts by weight of copper powder, 1 to 5 parts by weight of glass powder, and 40 to 100 parts by weight of a photosensitive liquid (photoresist) in which a photosensitive resin is dissolved. Conductive paste is preferred. The copper powder preferably has a particle size of 0.5 to 12 μm, more preferably 1 to 3 μm. When the particle size of the copper powder is less than 0.5 μm, the copper powder becomes bulky and a large amount of photosensitive resin is required for forming a paste, so that the amount of the copper powder in the paste decreases, and When the particle size exceeds 12 μm, the printability of the paste and the sinterability of the copper powder deteriorate. The glass particles preferably have a particle size of 0.5 to 5 μm. When the particle size of the glass particles is less than 0.5 μm, the adhesion of the copper conductor layer to the substrate is low, and when it exceeds 5 μm, the copper conductor layer is soldered. Wettability with respect to.

The glass particles have a function of adhering the copper conductor layer to the ceramic substrate, and the glass particles are copper powder 1
When the amount is less than 1 part by weight with respect to 00 parts by weight, the adhesion to the substrate is deteriorated, and when the amount is more than 5 parts by weight, the solder wettability of the copper conductor layer is deteriorated. The softening temperature of the glass powder is 400 in order to make the copper wiring adhere well to the ceramic substrate.
It is preferably in the range of to 600 ° C. As the photoresist, for example, a positive type photoresist made of an alcohol-based, ester-based, or ketone-based solvent and an acrylic-based or imide-based photosensitive resin, for example, an alcohol-based, ester-based, or ketone-based Examples of the negative photoresist include a solvent and a photosensitive resin such as a rubber-based, acrylic-based, or phenol-based photosensitive resin. When the photoresist is less than 40 parts by weight with respect to 100 parts by weight of the copper powder, the amount of the paste powder If the amount exceeds 100 parts by weight, the filling degree of the copper powder in the photosensitive conductor paste becomes too low to form sufficiently densified wiring.

In the preparation of the photosensitive conductor paste, it is preferable to knead a photosensitive solution containing the copper powder, the glass powder, the photosensitive resin and the like by using a three-roll.
If three rolls are used, a photosensitive conductor paste in which the copper powder and the like are sufficiently dispersed in the photosensitive liquid can be obtained. In addition,
It is necessary to prepare the photosensitive conductor paste under yellow light in order to prevent the photosensitive resin from being exposed to light.

As a method of applying the photosensitive conductor paste to the ceramic substrate, a method of solid printing using a normal thick film printing screen is used. Therefore, the coating operation is extremely easy. Further, solid printing on the ceramic substrate does not necessarily need to be applied to the entire surface of the ceramic substrate, and solid printing may be performed on the wiring portion and its periphery by a bar coating method. In addition to this, when it is necessary to print the photosensitive conductor paste on the entire surface of the ceramic substrate, a coating method such as a roll coater method, a dipping method, a Wheeler method (spinner method) can be used.
After the application of the photosensitive conductor paste to the ceramics substrate is completed, the ceramics substrate may be left for an appropriate time to level the coated surface. 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. After the leveling is completed, the coated surface is dried to fix the copper powder on the ceramic substrate. As a drying condition, it is preferable to usually heat at 70 to 80 ° C. for about 10 minutes. It should be noted that, by sufficiently leveling the coated surface in this coating step, the flatness of the wiring is improved and the height of each wiring becomes equal,
It is not necessary to polish and smooth the ceramic substrate before the coating process. The thickness of the coating film formed by this coating step is preferably 5 to 20 μm. When the thickness of the coating film is less than 5 μm, the texture of the copper wiring after firing becomes rough, and when the conductor layer of the coating film exceeds 20 μm, it becomes difficult for ultraviolet rays to reach the bottom of the coating film, and the photoresist Is not sufficiently cured, and defective development is likely to occur, which is not preferable.

Next, as a developing treatment step, a step of exposing and developing the coating layer formed by the coating step to a predetermined wiring pattern is carried out. The exposure process may be performed by a usual method, for example, a contact method or a proximity method. In the development process after the exposure, a developer which is usually used in developing a photosensitive resin can be used, and the developing method can be an immersion rocking method or a spray method. After completion of the development process, it can be handled under white light.

Next, the developed ceramic substrate is heat-treated in an oxidizing atmosphere at a temperature at which organic substances such as the photosensitive resin in the coating layer decompose and scatter.

When a copper conductor paste using a normal resin is used, heating and firing are performed in a nitrogen atmosphere containing a trace amount of an oxidizing gas so that the resin is decomposed and scattered without oxidizing the copper. However, in the case of the photosensitive conductor paste used in the present invention, as described above, the content of organic substances such as the photosensitive resin in the conductor paste is high, and the photosensitive resin is hard to be decomposed in the developing step and is less susceptible to scattering. Since it is necessary to decompose and scatter the volatile resin, it is very difficult to perform heating and firing under conditions that copper is not oxidized.

In the present invention, since the heat treatment is carried out in an oxidizing atmosphere such as the air, the organic substances in the photosensitive conductor paste can be completely decomposed and scattered in a short time. The copper powder is once oxidized by this step, but is reduced to metallic copper by performing a reduction treatment in a later step.

As a condition for performing the heat treatment step in the atmosphere, it is preferable that the heat treatment temperature is 400 ° C. or higher. When the heat treatment temperature is lower than 400 ° C., organic substances cannot be completely decomposed and scattered. Here, when heat treatment is performed in an oxidizing atmosphere, copper oxidizes and becomes copper oxide, which causes volume expansion, but the filling state of the copper powder in the photosensitive conductor paste is low, and the glass powder melts and flows. For this reason, the change in the wiring shape due to the oxidative expansion of copper hardly occurs. Rather, the degree of filling of the copper oxide particles once increases due to the oxidative expansion of copper and they are bonded to each other, and the bonding is not lost even by the reduction process in the next step, so a densely sintered copper wiring can be obtained by the firing step. There is an advantage.

If another method is performed in this regard,
Considering what happens, the following can be considered. First, when the photosensitive conductor paste is fired in an atmosphere in which copper does not oxidize, the density of the copper wiring after sintering becomes low, so that the adhesion of the copper wiring to the substrate is reduced and the electrical resistivity is reduced. It causes problems such as high cost. Further, when the copper conductor paste used in the normal thick film method is used and fired in the atmosphere, the wiring shape is likely to change due to oxidative expansion due to the high filling degree of the copper powder. Furthermore, when using a copper oxide powder as a starting material and carrying out the same method as the present invention, since the initial filling degree of the copper oxide powder is low, mutual bonding does not occur, and the copper oxide is reduced to metallic copper in the reduction step. When it is reduced to a volume, it causes volume contraction, resulting in a copper wiring having extremely low density, low adhesion to the substrate, and high electrical resistivity.

Next, as a reduction treatment step, the copper powder in the coating layer oxidized in the heat treatment step is reduced. The reduction treatment is usually performed in a nitrogen atmosphere containing 1 to 10 vol% of hydrogen,
It is preferable to perform heat treatment in the range of 400 to 600 ° C. If the hydrogen content is less than 1 vol%, the reduction does not proceed sufficiently, and if the hydrogen content exceeds 10 vol%, the structure of the ceramic circuit board such as the ceramic substrate, the dielectric part, and the resistance part. The material is also easily reduced. When the temperature of the reduction treatment is less than 400 ° C., the reduction is difficult to proceed, and thus the reduction requires a long time.
If the temperature exceeds ℃, the constituent materials such as the ceramic substrate are easily reduced.

By the reduction treatment step, copper oxide is reduced to metallic copper.

Next, a firing step of sintering copper in a neutral atmosphere is performed. The neutral atmosphere refers to an inert gas atmosphere such as nitrogen containing no oxygen or hydrogen, and in the present invention, in order to densify the copper reduced to metallic copper in the above step and adhere to the substrate, the neutral atmosphere Bake in an atmosphere. Firing temperature is 60
0-1000 degreeC is preferable. When the firing temperature is less than 600 ° C., copper does not sinter densely, and the firing temperature is 1
When the temperature exceeds 000 ° C, copper is likely to melt.

On the copper fine wiring formed by the above method, copper is used for the purpose of further flattening the fine wiring and preventing the deterioration of the adhesiveness due to high temperature aging after soldering.
A metal such as gold or nickel may be plated to a thickness of about 2 to 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 copper fine wiring having excellent flatness, denseness, and adhesiveness on a ceramic circuit board.

Next, a method of manufacturing the second ceramics circuit board of the present invention will be described. In the second method for manufacturing a ceramics circuit board, a coating step of coating a photosensitive conductor paste containing copper powder, glass powder and a photosensitive resin as a main component on the ceramics substrate, and a coating layer formed by the coating step are predetermined. The developing treatment step of exposing and developing the wiring pattern of 1) and the heat treatment of the developed ceramic substrate in an oxidizing atmosphere at a temperature at which the photosensitive resin in the coating layer decomposes and scatters. The manufacturing method is the same as that of the ceramic circuit board.

Therefore, the ceramic substrate, the photosensitive conductor paste, etc. used may be exactly the same as in the first ceramic circuit substrate manufacturing method.

In the second method for manufacturing a ceramics circuit board, a reducing step of reducing the copper powder in the coating layer oxidized in the heat treatment step and a firing step of sintering the reduced copper powder are simultaneously performed. This is different from the first ceramic circuit board manufacturing method in which the oxidation step and the reduction step are sequentially performed.

When the reduction firing step of reducing and sintering the copper powder in the coating layer oxidized in the previous heat treatment step is performed, the heating temperature is high, and therefore it is a constituent material of the ceramic circuit board described above. It is necessary that the ceramic substrate, the dielectric portion, the resistance portion, and the like are made of a material having high reduction resistance that is not easily reduced. The heating temperature in this case is 600 to 1000.
C is preferred. If the firing temperature is lower than 600 ° C., the copper is not densely sintered, and if the firing temperature is higher than 1000 ° C., the copper is easily melted.

In the second ceramic substrate manufacturing method as well, on the copper fine wiring formed by the above-mentioned method, in order to further flatten the fine wiring and to prevent deterioration of the adhesiveness due to high temperature aging after soldering, etc. Alternatively, a metal such as copper, gold or nickel may be plated to a thickness of about 2 to 5 μm.

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 copper fine wiring having excellent flatness, denseness, and adhesiveness on a ceramic circuit board.

[0038]

According to the first method for manufacturing a ceramic circuit board according to the present invention, a coating step of coating a copper substrate, a glass powder and a photosensitive conductor paste containing a photosensitive resin as a main component on the ceramic substrate; A developing treatment step of exposing and developing the coating layer formed by the coating step to a predetermined wiring pattern, and the photosensitive resin in the coating layer is decomposed and scattered in an oxidizing atmosphere on the ceramic substrate subjected to the developing treatment. Since it includes a heat treatment step at a temperature, a reduction treatment step of reducing the copper powder in the coating layer oxidized in the heat treatment step, and a firing step of sintering copper in a neutral atmosphere, Fine copper wiring is formed in the process of applying and developing the conductive conductor paste, and the photosensitive resin etc. are completely removed by the process of heat treatment in an oxidizing atmosphere, and the oxidized copper oxide is reduced and baked. Excellent adhesion to a ceramic substrate, a dense copper fine wiring is formed.

Further, according to the second method for manufacturing a ceramics circuit board according to the present invention, a coating step of coating a photosensitive conductor paste containing copper powder, glass powder and a photosensitive resin as main components on the ceramics substrate, A developing treatment step of exposing and developing the coating layer formed by the coating step to a predetermined wiring pattern, and decomposing the photosensitive resin in the coating layer in an oxidizing atmosphere on the ceramic substrate subjected to the developing treatment, Since it includes a step of heat-treating at a temperature that scatters, and a reduction firing step of reducing and sintering the copper powder in the coating layer oxidized in the heat-treating step, the step of applying and developing the photosensitive conductor paste. Fine copper wiring is formed with
Photosensitive resin etc. are completely removed by the process of heat treatment in an oxidizing atmosphere, oxidized copper oxide is reduced, and the process of baking at the same time forms fine copper fine wiring with excellent adhesion to the ceramic substrate. To be done.

[0040]

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 Under yellow light, 100 parts by weight of a copper powder having a particle size of 4 μm, ₂ parts by weight of a glass powder (PbO—B ₂ O ₃ —SiO ₂ system, softening point 500 ° C.), negative type photo 55 parts by weight of a resist (mainly composed of an acrylic polymer) was kneaded with a three-roll mill to prepare a photosensitive conductor paste. Next, using the photosensitive conductor paste, the size of which is 60 mm × 60
Screen printing (solid printing) was performed on the wiring part of the alumina sintered substrate of mm and its periphery through a stainless mesh by a bar coating method. The thickness of the print coating layer at this time was 6 μm. Next, the printed alumina substrate was leveled for 10 minutes, dried at 80 ° C. for 10 minutes, and fixed on the alumina substrate. The internal structure of the wiring part after printing is
SEM observation after cutting so that the inside can be seen,
Copper particles and glass particles were satisfactorily dispersed in the photosensitive resin resin, the particles were less in contact with each other, and the packing degree of the particles was low.

Next, exposure and development steps were performed. In the conductor layer containing the photosensitive resin formed on the alumina substrate in the above step,
A photomask on which a predetermined wiring pattern was formed was brought into contact, and ultraviolet rays were irradiated from above to expose the conductor layer containing the photosensitive resin. The substrate after the exposure treatment was developed by a dipping and rocking method using a developer of a 1 wt% sodium carbonate aqueous solution, and rinsed with pure water.

The step of decomposing and scattering organic substances such as photosensitive resin by heat treatment was carried out by heating the substrate developed by the above method at 500 ° C. for 20 minutes in the atmosphere. By this process, the cured photosensitive resin in the wiring was decomposed and scattered, and the copper particles in the photosensitive resin were oxidized to copper oxide. It was in the form of a film because it was formed. Further, the film-shaped copper oxide formed was adhered to the alumina substrate by melting and flowing of the glass particles.
After this step, it was performed under white light.

Reduction of copper oxide to metallic copper was carried out by holding at 500 ° C. for 10 minutes in a nitrogen atmosphere containing 10 vol% hydrogen. In this reduction step, volume contraction occurred due to the reduction of copper oxide to metallic copper, but the copper particles bonded to each other remained bonded as they were, and the copper oxide film was formed by glass. Since it was fixed on the alumina substrate, it did not peel off from the alumina substrate even when it became a metallic copper film.

Finally, the reduced copper on the alumina substrate
It was sintered by holding it at 900 ° C. for 10 minutes in a nitrogen atmosphere and firmly fixed to an alumina substrate. As a result, the copper wiring was sintered sufficiently densely.

By the above process, copper fine wiring having a line width of 30 μm and a distance between the lines of 20 μm could be formed. The conductivity, adhesive strength and solder wettability of the formed copper fine wiring were evaluated by the following procedures.

Conductivity is evaluated by measuring conductor characteristic values. Specifically, from the four-terminal resistance measurement and the line width and film thickness of the copper wiring, the film thickness of 20 μ
Obtain the sheet resistance value in m.

Bonding Strength A copper conductor layer having a size of 2 mm × 2 mm square was formed on the alumina substrate by the above process, and 3 ± 0 in a 63% Sn-37% Pb solder bath maintained at a temperature of 230 ± 3 ° C. .5
After dipping for a second, a 0.6 mmφ tin-plated copper wire is soldered on it with a soldering iron. Next, the tin-plated copper wire is bent 90 ° at a position 1 mm from the end of the coating to be perpendicular to the substrate, and with the substrate fixed, the tin-plated copper wire is pulled at a speed of 10 cm / min by a tensile tester,
The adhesive strength when the tin-plated copper wire is peeled off from the substrate is measured and used as the adhesive strength value. The measurement of the adhesive strength,
Immediately after soldering (initial adhesive strength) and at 150 ° C 1
After aging for 000 hours (adhesive strength after aging), two types of conditions are set.

Solder wettability A copper conductor layer having a size of 4 mm × 4 mm square was formed on the alumina substrate by the above process, and 3% was put in a 63% Sn-37% Pb solder bath maintained at a temperature of 230 ± 3 ° C. 0.5
Immerse for 2 seconds and measure the coverage of the deposited solder visually.

When the characteristic values of the copper fine wiring formed by the above process were measured by the above evaluation method, the sheet resistance value was 1.5 mΩ / □ and the initial adhesive strength was 3.0 kg /
4 mm ² , the adhesive strength after aging is 2.6 kg / 4 mm ² ,
The solder wettability was 100%, which was an excellent characteristic. When the flatness of the wiring surface was measured with a surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd., it was ± 2 μm.

Next, a new copper conductor layer was formed on the copper fine wiring by electrolytic plating to a thickness of 2 μm. The conditions of the electroplating are as follows: plating solution (CuSO ₄ , 5H ₂ O: 75 g / L, concentrated sulfuric acid: 17
^{0g / L, Cl -: 60ppm} , brighteners: at trace amounts) in, using copper containing 0.3% phosphorus as anode, the current density of 1.5A / dm ^2, was 30 minutes conduction time.

The flatness of the surface of the copper fine wiring made of the plated copper conductor layer is as high as ± 0.5 μm or less, and the initial adhesive strength is 3.0 kg / 4.
mm ² , the adhesive strength after aging was 3.0 kg / 4 mm ² , and the solder wettability was 100%.

[Example 2] The same alumina sintered substrate as in Example 1 was used, and a photosensitive conductor paste was screen-printed on the substrate in the same manner as in Example 1 to carry out exposure, development, decomposition of organic substances and scattering treatment. went. Next, in a nitrogen atmosphere containing 10 vol% hydrogen, reduction and firing were carried out by holding at a peak temperature of 900 ° C. for 10 minutes to form a copper fine wiring having a line width of 30 μm and a line spacing of 20 μm.

When the characteristic value of the copper fine wiring formed by the above process was measured, the sheet resistance value was 1.4 mΩ /
□, initial adhesive strength is 3.1 kg / 4 mm ² , adhesive strength after aging is 2.2 kg / 4 mm ² , solder wettability is 100%
And showed excellent characteristics. The flatness of the wiring surface is ± 2μ
It was m.

Next, a new copper conductor layer was formed on the copper fine wiring to a thickness of 2 μm by the electrolytic plating method as in Example 1, and the copper conductor layer was plated. The flatness of the copper fine wiring surface is ± 0.5 μm or less, which is extremely high, and the initial adhesive strength is 3.1 kg / 4.
mm ² , the adhesive strength after aging was 3.0 kg / 4 mm ² , and the solder wettability was 100%.

Example 3 100 parts by weight of copper powder having a particle size of 6 μm, glass powder (PbO—B ₂ O ₃ —SiO ₂ system, softening point 500 ° C.) 2
20 parts by weight in the same manner as in Example 1 except that a photosensitive conductor paste was prepared by kneading 50 parts by weight of a negative photoresist (mainly composed of an acrylic polymer) with 3 rolls. Then, copper fine wiring having a space of 15 μm was formed.

When the characteristic value of the copper fine wiring formed by the above process was measured, the sheet resistance value was 1.6 mΩ /
□, initial adhesive strength is 2.7 kg / 4 mm ² , adhesive strength after aging is 2.0 kg / 4 mm ² , solder wettability is 100%
And showed excellent characteristics. The flatness of the wiring surface is ± 2μ
It was m.

Next, a new copper conductor layer having a thickness of 2 μm was formed on the copper fine wiring by electrolytic plating in the same manner as in Example 1. The copper conductor layer was plated. The flatness of the copper fine wiring surface is ± 0.5 μm or less, which is extremely high, and the initial adhesive strength is 2.7 kg / 4.
mm ² , the adhesive strength after aging was 2.5 kg / 4 mm ² , and the solder wettability was 100%.

Example 4 100 parts by weight of copper powder having a particle size of 4 μm, glass powder (PbO—B ₂ O ₃ —SiO ₂ system, softening point 500 ° C.) 5
30 parts by weight in the same manner as in Example 1 except that a photosensitive conductor paste was prepared by kneading parts by weight and 55 parts by weight of a negative photoresist (mainly composed of an acrylic polymer) with a three-roll mill. A copper fine wiring having a line spacing of 20 μm was formed.

When the characteristic value of the copper fine wiring formed by the above process was measured, the sheet resistance value was 1.7 mΩ /
□, the initial adhesive strength was 3.2 kg / 4 mm ² , the adhesive strength after aging was 2.7 kg / 4 mm ² , and the solder wettability was 90%, which were excellent characteristics. The flatness of the wiring surface is ± 2 μm
Met.

Next, a new copper conductor layer having a thickness of 2 μm was formed on the copper fine wiring by electrolytic plating in the same manner as in Example 1. The copper conductor layer was plated. The flatness of the copper fine wiring surface is ± 0.5 μm or less, which is extremely high, and the initial adhesive strength is 3.2 kg / 4.
mm ² , the adhesive strength after aging was 2.9 kg / 4 mm ² , and the solder wettability was 100%.

Example 5 100 parts by weight of copper powder having a particle size of 4 μm, glass powder (PbO—B ₂ O ₃ —SiO ₂ system, softening point 500 ° C.) 2
A line width of 60 μm was obtained in the same manner as in Example 1 except that a photosensitive conductor paste was prepared by kneading 60 parts by weight of a positive photoresist (mainly composed of an acrylic polymer) with 3 rolls. A copper fine wiring having a line spacing of 30 μm was formed.

When the characteristic value of the copper fine wiring formed by the above process was measured, the sheet resistance value was 1.7 mΩ /
□, initial adhesive strength is 2.9 kg / 4 mm ² , adhesive strength after aging is 2.4 kg / 4 mm ² , solder wettability is 100%.
And showed excellent characteristics. The flatness of the wiring surface is ± 2μ
It was m.

Next, as in Example 1, a new copper conductor layer was formed on the copper fine wiring to a thickness of 2 μm by electroplating, and the copper conductor layer was plated. The flatness of the copper fine wiring surface is ± 0.5 μm or less, which is extremely high, and the initial adhesive strength is 2.9 kg / 4.
mm ² , the adhesive strength after aging was 2.8 kg / 4 mm ² , and the solder wettability was 100%.

[Comparative Example 1] The same alumina sintered substrate as in Example 1 was used, and a photosensitive conductor paste was screen-printed on the substrate in the same manner as in Example 1, and the substrate was exposed and developed. Next, under a nitrogen atmosphere containing 30 ppm of oxygen, 3
When the temperature was raised to 900 ° C. in 0 minutes, held at 900 ° C. for 10 minutes, and then baked in a condition that it was cooled to room temperature in 30 minutes, the resin in the wiring did not decompose and scatter, and remained as residual carbon, Sintering of the powder hardly proceeded, the sheet resistance value was 20 mΩ / □, and the copper fine wiring could not be formed on the alumina substrate.

[0066]

As described in detail above, in the first method for manufacturing a ceramic circuit board according to the present invention, a photosensitive conductor containing copper powder, glass powder and a photosensitive resin as main components is provided on the ceramic substrate. A coating step of coating a paste, a developing treatment step of exposing and developing the coating layer formed by the coating step to a predetermined wiring pattern, and a coating process of the ceramic substrate subjected to the developing treatment under an oxidizing atmosphere. Heat treatment at a temperature at which the photosensitive resin inside decomposes and scatters,
Since it includes a reduction treatment step of reducing the copper powder in the coating layer oxidized in the heat treatment step and a firing step of sintering copper in a neutral atmosphere, the ceramics can be easily operated and at low cost. It is possible to form copper fine wiring having excellent flatness, denseness, and adhesiveness on a circuit board.

Further, in the second method for manufacturing a ceramic circuit board according to the present invention, a coating step of coating a photosensitive conductor paste containing copper powder, glass powder and a photosensitive resin as a main component on the ceramic substrate. A developing treatment step of exposing and developing the coating layer formed by the coating step to a predetermined wiring pattern, and decomposing the photosensitive resin in the coating layer in the oxidizing atmosphere of the ceramic substrate subjected to the developing treatment. Since the method includes a heat treatment step at a scattering temperature and a reduction firing step of reducing and sintering the copper powder in the coating layer oxidized in the heat treatment step, Similarly, the copper fine wiring excellent in flatness, denseness, and adhesiveness can be formed on the ceramic circuit board with easy operation and low cost.

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

Claims (2)

[Claims] 1. A coating step of coating a copper substrate, a glass powder and a photosensitive conductor paste containing a photosensitive resin as a main component on a ceramic substrate, and a coating layer formed by the coating step is exposed to a predetermined wiring pattern. A developing treatment step of developing, a step of heat treating the ceramic substrate subjected to the developing treatment in an oxidizing atmosphere at a temperature at which the photosensitive resin in the coating layer is decomposed and scattered, A method of manufacturing a ceramic circuit board, comprising: a reduction treatment step of reducing copper powder in a coating layer; and a firing step of sintering copper in a neutral atmosphere. 2. A coating step of coating a copper substrate, a glass powder and a photosensitive conductor paste containing a photosensitive resin as a main component on a ceramic substrate, and a coating layer formed by the coating step is exposed to a predetermined wiring pattern. A developing treatment step of developing, a step of heat treating the ceramic substrate subjected to the developing treatment in an oxidizing atmosphere at a temperature at which the photosensitive resin in the coating layer is decomposed and scattered, And a reduction firing step of reducing and sintering the copper powder in the coating layer.