JPS62194694A - Manufacture of ceramic circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] When printing a pattern, grooves are formed in the green sheet in advance using a press die with the same pattern as the conductor pattern, and a low-resistance conductor circuit with excellent printability is formed in the grooves. A method is presented.

[Industrial application field]

The present invention relates to a method for manufacturing a ceramic circuit board in which a conductor pattern is formed on a green sheet in a pre-ceramic firing step.

In recent years, with the development of highly integrated scale and high speed LSIs, the number of connection wiring circuits that must be processed by the laminated substrates on which they are mounted tends to increase.

For this reason, the wiring pitch or grid pitch of the circuit board that houses the conductor pattern is becoming increasingly narrower, and the width of the pattern conductor is gradually becoming smaller. are doing.

In view of the above-mentioned circumstances, the present invention has been developed for high-density mounting circuit boards that require high-speed performance, etc., using the conventional screen printing method using copper paste, for example.

The purpose is to form a stable, low-resistance wiring conductor pattern on a green sheet.

[Conventional technology]

Conventionally, when forming a wiring conductor pattern on a ceramic substrate, it is done by screen printing on the ceramic substrate after firing, or by applying a conductive paste (for example) to a ceramic green sheet before firing.

A circuit pattern is formed by screen printing a paste (made of powder of high-melting metals such as tungsten and molybdenum) and firing it in a reducing atmosphere at around 1200°C. However, recently, base metal powders such as copper (Cu
) Pastes are widely used because they have excellent conductivity, adhesion to substrates, and soldering or bonding properties, and are lower in cost than precious metals.

An example of printing a conductor pattern using such a paste base material is shown in the plan view of FIG. 3 (al) and the cross-sectional view of a local circuit board in FIG. ,
(a) It is a sectional view of the index line AA part of a figure.

However, in screen printing, for example, the film thickness h and pattern width are determined depending on the screen mesh and paste viscosity, so the conductor circuit is limited to the cross-sectional dimensions shown in Figure (b). be.

This is because, for example, the above-mentioned h/w (referred to as aspect ratio) cannot be obtained large, and furthermore, the resin component in the paste of the conductor pattern after firing is dissipated, resulting in a decrease in the aspect ratio.

In order to improve this problem, a highly viscous base I. may be used, but in this case, for example, printability deteriorates and wire breakage or cranking occurs during pattern baking, making it impossible to form a stable pattern.

[Problem that the invention seeks to solve]

As mentioned above, in forming a conductor circuit by the screen printing method, it is difficult to obtain a high aspect ratio (h/w≧1) of the cross-sectional shape using a low-viscosity paste with good pattern printing properties. The problem with highly viscous pastes is that wire breakage and cranking occur during firing.

This makes it difficult to apply the screen printing method to the recent high-density circuit pattern formation in which the width W is narrow and the thickness h is thick.

The present invention is achieved by forming a conductor pattern having an aspect ratio of h≧1 and having excellent printing properties.

The objective is to form a ceramic multilayer substrate suitable for high-density packaging that requires high speed.

[Means for solving problems]

For green sheets before ceramic firing.

The same pattern as the wiring pattern to be screen printed is formed as a convex pattern on the stamp board.

The method for manufacturing a ceramic circuit board of the present invention includes stamping the stamp substrate on a green sheet to preform a groove pattern, and then forming a conductor circuit on the groove pattern by screen printing. This solves the problem.

[Effect]

The pre-formed groove pattern is effective in solving the conventional problem of difficulty in achieving a high aspect ratio of cross-sectional shapes during screen printing related to board wiring.

Therefore, a low viscosity conductive paste with good screen printability is used. Further, a thick film (low resistance) conductor wiring pattern for board wiring can be realized very easily.

〔Example〕

Hereinafter, nine embodiments of the present invention will be described with reference to FIGS. 1 and 2.

Figure 1 shows the green sheet before firing.

FIG. 3 is a schematic cross-sectional view of forming a groove pattern.

In the figure, reference numeral 10 denotes a press die or stamper on which a convex inverted pattern 11 is formed, for example, made of a stainless steel plate.

The inverted pattern 11 of the stamper 10 is drawn by phototransferring the same artwork pattern (which is a light-transmitting work film serving as a circuit pattern original) when forming a screen printing mask.

Pattern drawing involves exposing and projecting the artwork pattern onto a stainless steel plate coated with a photoresist in advance, removing the unexposed resist portion, and etching the surface of the stainless steel plate by at least 30 μm with a chemical etching solution.
By corroding about m, a convex inverted pattern 11 can be formed on the stainless steel plate.

A stamper 1° on which a convex inverted pattern 11 is formed,
By pressing the green sheet 13 in the direction of the large arrow 14, a groove having the same pattern as the wiring pattern is preformed.

Green sheet 1 on which the preformed pattern grooves are formed
In contrast to No. 3, if a conductor wiring pattern is printed using a mask screen in the same manner as the conventional method, a circuit with a high aspect ratio as desired can be formed.

FIG. 2(a) is a cross-sectional view of a laminated sheet in a pre-ceramic firing process in which the green sheets of FIG. 1 are laminated to form a multilayer circuit board, and FIG. 2(b) is a high aspect ratio,
FIG. 3 is a cross-sectional view of the conductor circuit section 15 with hik4≧1.

By firing a laminate of such green sheets, a ceramic multilayer circuit board containing a high-density and low-resistance wiring pattern can be obtained.

〔Effect of the invention〕

As is clear from the above explanation, according to the method of manufacturing a ceramic circuit board of the present invention, a conductor pattern with a high aspect ratio can be manufactured extremely easily, so that it can be used, for example, in a module circuit for a computer that requires high speed. If used in a multilayer circuit board, the effect can be significant.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of forming the groove pattern of the present invention (
al is a cross-sectional view of laminated green sheet bodies according to FIG. 1; Figure (b) is a cross-sectional view of a conductor with a high aspect ratio. FIG. 3(a) is a front view of a board showing an example of a conventional conductor circuit pattern. The same figure (BL is a cross-sectional view of the conductor section taken along the index line A-A in the FA1 figure. In the figure, 10 is a stamper on which a convex pattern 11 is formed. 13 is a green sheet. ) ゛j-Sissy 1-1 Haji layered fkowr surface closed No. 1
7 (θ)

Claims (1)

[Claims] The present invention is characterized by comprising means for forming a concave groove pattern by stamping a convex pattern matching a wiring pattern on a green sheet before firing the ceramic, and then forming a conductive circuit in the concave groove pattern by a printing method. A method for manufacturing a ceramic circuit board.