JPH05304363A - Manufacture of ceramic multilayer board - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a ceramic multilayer board in which a transfer malfunction occurring at the time of laminating is solved and which has excellent mass productivity and a low manufacturing cost in the method for manufacturing the board to realize a high density mounting of effective means for reducing in size of an electric apparatus. CONSTITUTION:After a first insulating layer 3 is printed on a wiring pattern 2 formed on a base film 1 at the time of manufacturing a transfer sheet 12, printing after a second insulating layer 5 or the following layer is sequentially conducted in a wide pattern to obtain the sheet 12 in which a protrusion of an edge 4 generated on the layer 3 is reduced or eliminated. The sheet 12 is thermally transferred to be laminated on a heat resistance board. Thus, the step of processing its edge part is eliminated to enhance its mass productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic multi-layer substrate used for forming circuits of electronic devices and the like.

[0002]

2. Description of the Related Art A ceramic multilayer substrate having therein a three-dimensional array of interconnected pattern layers is known as a green sheet multilayer method (Japanese Patent Publication No. 40-8458, Japanese Patent Publication No. 55-8837, and Japanese Patent Publication No. 55-8837). Many manufacturing methods have been proposed, such as Japanese Patent Publication No. 61-45876), thick film printing method (Japanese Patent Publication No. 57-19599), and transfer method.

In the green sheet multi-layer method, shrinkage occurs during firing. Therefore, in order to manufacture the green sheet without destroying the intended pattern arrangement, the slurry composition for producing the green sheet, the powder dispersion state, or the sheet thickness. , The pressurizing condition, etc. must be controlled extremely precisely. If this is not achieved, warpage and undulation will occur in the fired body, and as a further serious problem, conduction failure of the via hole will occur due to misalignment between the layers. The thick film printing method can solve the problems of the green sheet multilayer method. This is because according to this construction method, there is no dimensional change of the molded body in the two-dimensional direction during firing, and the pattern arrangement and the position of the via hole are not displaced. However, in this method, a method of forming a reverse pattern of a conductor pattern with an insulating paste (Japanese Patent Publication No. 57-54956).
Japanese Patent Publication No. 58-26680), and an insulating layer is printed a plurality of times on the conductor pattern, a multilayer substrate having a flat surface and reliable cannot be obtained.
Further, repeating the firing by the necessary total number has a disadvantage that the conductor and the insulator must be repeatedly given a thermal history under the same conditions as those of firing.
That is, deterioration of insulation resistance due to diffusion of the conductor material into the insulating layer and deterioration due to heat are extremely undesirable from the viewpoint of reliability.

As a method aiming at improving the drawbacks of these methods, there is a method in which a printed ceramic sheet containing wiring is thermally transferred and laminated on a heat resistant substrate.

[0005]

However, the above-mentioned conventional method by thermal transfer has a serious drawback that the pressure is non-uniform due to the swelling that occurs at the pattern edge when the insulating layer is printed, resulting in defective transfer. .. In order to eliminate this transfer failure, a method of removing by removing the raised portion of the insulating total edge is considered, but the increase in manufacturing cost due to that process will increase the mass productivity and cost performance of the ceramic multilayer substrate by the transfer method. Significantly lowers.

Further, since it is a transfer sheet having a wiring layer built-in, a step due to the thickness of the wiring layer appears on the surface of the insulating layer formed on the wiring layer, and depending on the type of wiring material, this may be the swelling of the edge of the insulating layer. There is also a problem that similar transfer defects may occur.

The present invention is intended to solve the above problems,
An object of the present invention is to provide a method for manufacturing a ceramic multi-layer substrate which has high productivity and does not cause transfer defects.

[0008]

In order to achieve the above object, the present invention prints a conductive paste on a base film, dries it to form a wiring pattern, and prints an insulating paste so as to cover it. Then, after drying, print the insulating paste with a pattern larger than the insulating pattern so as to cover the edge part of the insulating pattern,
A transfer sheet formed by drying is heat-transferred and laminated on a heat-resistant substrate, and the first insulating layer formed by an insulating paste has a first emulsion layer thickness larger than the dry film thickness of the wiring pattern. Using a screen printing plate and a squeegee made of hard metal or ceramic or glass, and then using a second screen printing plate having an emulsion thickness greater than the dry film pressure of said first insulating layer and wiring pattern. The transfer sheet is manufactured by repeating the following insulating layer formation.

[0009]

Therefore, according to the present invention, as shown in FIG. 1A, when the first insulating layer 3 is printed on the wiring film 2 which is printed on the base film 1 and dried, the edge portion 4 is printed. As shown in FIGS. 1 (b) and 1 (c), the generated bulge enlarges the pattern at the time of printing the insulating layer after the second time, so that the edge portion 4 is removed from the second insulating layer 5 and the third insulating layer 6. It will be reduced by overprinting. As a result, in the area A to be transferred, it is possible to obtain a flat transfer sheet without swelling, and heat transfer can be performed without any defect.

As shown in FIGS. 2A and 2B, the squeegee 8 used for printing the insulating paste 7 is made of a hard material, and the emulsion 9 for the screen plate is used.
Of the wiring pattern 2 already formed by printing or the dry film thickness of the wiring pattern 2 and the first insulating layer 3 allows the mesh 10 of the screen plate to have the wiring pattern 2 already formed by printing or The insulating paste 7 can be printed without coming into contact with the surface of the first insulating layer 3. That is, the surface of the insulating layer in the wet state immediately after printing can be printed in a flat state without being affected by the wiring pattern embedded therein or the dry film thickness of another insulating layer. Therefore, the level difference on the surface that occurs when the insulating layer is dried appears depending only on the shrinkage rate of the insulating paste when it is dried, and can be greatly reduced by repeating this, and thermal transfer can be reduced. You can do it without any defects.

[0011]

EXAMPLE An example of the present invention will be described below.

Example 1 FIGS. 1 (a) and 1 (b) show a process for producing a transfer sheet in an example of the present invention. As shown in the figure, a PET film (product name: 75 μm thick) Base film 1 for therapies, manufactured by Toray, etc.
A wiring pattern 2 is printed and formed using a commercially available thick film silver paste (product number DD-1411, manufactured by Kyoele Co., Ltd.) on the wiring pattern 2 with a screen printing plate having an emulsion thickness of 25 μ and a stainless steel 200 mesh. Insulator paste 7 with the composition shown below in a 60 × 60 mm square pattern
Printed and dried.

Alumina + Borosilicate glass powder 70% by weight Butyral resin + Plasticizer 15% by weight Solvent (butyl carbitol) 15% by weight After drying, a flat portion of the first insulating layer 3 shown in FIG. The thickness was 32 μm, and the thickness of the edge portion 4 was 45 μm.

Next, using a screen printing plate having the same specifications,
The second printing was performed on the insulating layer 3 of Stroke 1 in a 62 × 62 mm square pattern. That is, as shown in FIG. 1B, the second insulating layer 5 was provided outside the edge portion 4 of the first printed insulating layer 3 by 1 mm. By this printing, the thickness of the flat portion composed of the first insulating layer 3 and the second insulating layer 5 is 59 μm, and the thickness of the protruding portion 10 due to the swelling of the edge portion 4 generated during printing of the first insulating layer 3. Was 66 μm.

Further, as shown in FIG. 1 (c), printing of the third insulating layer 6 is performed in a square pattern of 62 × 62 mm,
The third insulating layer 6 is printed and provided on the second insulating layer 5,
After drying, when the thickness of each portion was examined, the thickness of the portion corresponding to the upper portion of the edge portion 4 generated during printing of the first insulating layer 3 was 91 μm, and the first insulating layer 3 and the second insulating layer 3 were separated. Thickness 89 of the flat portion made of the layer 5 and the third insulating layer 6
It was almost the same as μm. Further, it was found that the thickness of the edge convex portion 11 generated during the third printing was 71 μm, which was thinner than the above-mentioned flat portion.

The transfer sheet 12 prepared as described above
5 sheets were prepared and sequentially transferred onto an alumina substrate (not shown) provided with an adhesive layer by heating to form a laminate. The transfer conditions at this time are as follows: set temperature of the stainless steel surface plate is 80 ° C., pressure is 9
The pressure was 0 kg / cm ² and the pressing time was 10 seconds. The outer peripheral portion is left on the base film 1 after peeling from the area A shown in FIG. 1C, and the area A to be transferred is completely transferred onto the alumina substrate, and transfer failure occurs up to the fifth layer. There wasn't.
This laminated body was subjected to binder removal treatment in the air and then fired to obtain a ceramic multilayer substrate having five wiring layers, but no defects such as cracks or curling of the insulating layer were observed.

(Example 2) A base film 1 on which a wiring pattern 2 was formed in the same manner as in Example 1 was used to form an insulating paste 7 having the composition shown below in a square pattern of 60 × 60 mm. (A) Alumina + borosilicate glass powder 65% by weight Butyral resin + rosin + plasticizer 15% by weight Solvent (butyl carbitol) 20% by weight The first insulating layer 3 shown in FIG. The specifications of the screen plate are 150 mm stainless steel with an emulsion thickness of 25 μm.
It was a mesh. As a result, the thickness of the region A in the flat portion of FIG. 1 (a) was 45 μm, and the thickness of the edge portion 4 was 56 μm.

Further, using a screen plate having the same specifications and having a pattern of 62 × 62, the second insulating layer 5 shown in FIG. 1 (b) was formed by printing in the same manner as in (Example 1). As a result, the thickness of the region A in the flat portion shown in FIG. 2B was 88 μm, and the thickness of the protrusion 10 was 94 μm.

Using the transfer sheet 12 thus obtained, three layers were transferred onto an alumina substrate (not shown) provided with an adhesive layer under the transfer conditions shown in (Example 1). A laminate similar to that of Example 1) was obtained, and a ceramic multilayer substrate in which the insulating layer had no defects even when subjected to heat treatment could be manufactured.

As can be seen from the above, in the present invention,
The printing of the insulating layer at the time of the transition may be performed by appropriately selecting the number of times depending on the number of transfer laminated layers and the rheological property of the insulating paste 7. Further, the object of the present invention can be achieved if the insulating layer is formed to have a thickness equal to or more than the thickness required from the requirements of withstand voltage, insulation resistance and reliability.

(Example 3) A commercially available copper oxide paste (product number DD-310) was formed on a base film 1 made of a PET film having a thickness of 75 μm (trade name: Serapile, manufactured by Toray).
The wiring pattern 2 was formed by printing. The film thickness of this was 19 to 20 μm.

Emulsion thickness 35μ, stainless steel 20
On a 0 mesh screen printing plate, an insulating paste 7 having the composition shown below was printed on the wiring pattern in a square pattern of 60 × 60 mm.

Alumina + borosilicate glass powder 70% by weight Butyral resin + plasticizer 15% by weight Solvent (butyl carbitol) 15% by weight At this time, as the squeegee 8, an alumina rod having a diameter of 6 mm is mirror-polished. I was there. After drying, the thickness of the region A of the flat portion of the first insulating layer 3 shown in FIG.
The edge portion 4 has a thickness of 55 μm. Moreover, the step due to the wiring pattern 2 appearing in the flat portion is 7 to 8 μm.
It was m.

Next, with the same specifications, the emulsion thickness is 60
A second insulating layer 5 is formed on the above-mentioned first insulating layer 3 in a 62 × 62 mm square pattern using a screen printing plate of μm.
Was printed. As a result of this printing, the thickness of the region A of the flat portion consisting of the first insulating layer 3 and the second insulating layer 5 shown in FIG. 1B is 79 μm, and the edge portion generated during printing of the first insulating layer 3 The protrusion 10 has a thickness of 80 μm due to the swelling of the wiring pattern 4 and the wiring pattern 2 in the flat portion.
The difference in level due to was 2 to 3 μm.

The transfer sheet 12 prepared as described above
5 were heat-transferred under the same conditions as in Example 1 to prepare a laminated body of 5 wiring layers. The outer peripheral portion of the base film 1 after peeling remains from the area A shown in FIG.
The area A to be transferred was completely transferred onto the alumina substrate, and no transfer failure occurred up to the fifth layer. After debinding the laminated body in the atmosphere, reduction in a hydrogen stream,
A ceramic multilayer substrate with copper wiring was obtained by firing in a nitrogen stream, but no defects such as cracks or swelling of the insulating layer were observed in this.

As can be seen from this embodiment, the present invention can be applied to the case where the wiring material is copper made of copper oxide as a raw material.

(Comparative Example) In (Example 1), after printing the first insulating layer 3, the second and third insulating layers 5 and 6 were formed.
When each of the above was printed, a transfer sheet was prepared in the case where the same size of 60 × 60 mm as the case of printing the first insulating layer 3 was overlapped and printed. The thickness of the flat area A is 87 μm, and the height of the edge portion 4 is 9 μm.
It was 8 μm.

When this was transferred onto an alumina substrate provided with an adhesive layer under the transfer conditions shown in (Example 1), when the base film was peeled off, the central portion of the insulating layer, that is, the portion of the area A, was formed on the base film 1. A transfer failure that left a mark occurred.

[0029]

As is apparent from the above embodiments, the present invention is to print a conductive paste on a base film, dry it to form a wiring pattern, and then print an insulating paste to cover it. A transfer sheet is manufactured by drying to form an insulating layer, printing an insulating paste with a pattern larger than that of the insulating layer so as to cover the edge portion, and drying to form another insulating layer. In addition, the first insulating layer is formed by using a first screen printing plate having an emulsion thickness larger than the dry film thickness of the wiring pattern and a squeegee made of hard metal, ceramic or glass, After that, the second insulating layer is formed using the second screen printing plate having an emulsion thickness larger than the dry film thickness of the insulating layer and the wiring pattern. By adopting the structure of manufacturing the transfer sheet by returning it, it is possible to eliminate the transfer failure when heat transferring and stacking on the heat resistant substrate, and it is possible to manufacture the ceramic multilayer substrate with high productivity. is there.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view showing the structure of a transfer sheet after printing a first first insulating layer according to an embodiment of the present invention (b) printing a second next insulating layer Sectional view showing the structure of the transfer sheet after performing (c) Sectional view showing the structure of the transfer sheet after printing the third next insulating layer

FIG. 2 (a) is a cross-sectional view of an essential part showing a state in which an insulating paste according to an embodiment of the present invention is printed on a wiring pattern. (B) An insulating paste is printed on a first insulating layer in the same embodiment. The main part showing the state

[Explanation of symbols]

 1 Base Film 2 Wiring Pattern 3 First Insulating Layer (First Insulating Layer) 5 Second Insulating Layer (Next Insulating Layer) 7 Insulator Paste 8 Squeegee 9 Emulsion 12 Transfer Sheet

Claims (2)

[Claims] 1. A conductor paste is printed on a base film and dried to form a wiring pattern, and then an insulator paste is printed so as to cover the conductor pattern and dried, and a pattern larger than the insulator pattern is formed. A method for manufacturing a ceramic multi-layer substrate, comprising: printing an insulating paste so as to cover an edge portion of the insulating paste; and drying a transfer sheet, which is heat-transferred and laminated on a heat-resistant substrate. 2. A first screen printing plate having an emulsion thickness larger than a dry film thickness of a wiring pattern, and a hard metal or ceramic or glass squeegee for the first formation of an insulating layer by an insulating paste. A second screen printing plate having the emulsion thickness larger than the dry thickness of the first insulating layer and the wiring pattern, and then performing the subsequent insulating layer formation to repeatedly produce a transfer sheet. The method for producing a ceramic multilayer substrate according to claim 1, wherein the ceramic multilayer substrate is manufactured.