JPH04100295A - Manufacture of multilayer ceramic circuit board - Google Patents

Abstract

PURPOSE:To make exfoliation between layers hard to occur, by a method wherein, after two green sheets of different composition are stacked, heated, pressed, and unified in a body to form a unit green sheet, said unit green sheet laminates are aligned, laminated, pressed with pressure, and then baked. CONSTITUTION:A green sheet A and a green sheet B of different composition are aligned, and then formed in a unified body by applying pressure under the condition of 70 deg.C and 2Mpa. A viahole of 90mum in diameter is punched in the above unified body. In this hole, Cu paste is buried by a screen printing method, and a wiring pattern of 100mum in width and 30mum in thickness is formed. Next, 50 sheets of the unified body of green sheets are aligned and laminated, pressed with pressure, and formed in a unified body, thereby obtaining a laminate. Said laminate is baked for 4 hours at 1000 deg.C in an N2 atmosphere, and a multilayer ceramic circuit board is obtained, in which no exfoliation is found.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a ceramic circuit board obtained by laminating green sheets with different compositions, the present invention relates to a method of manufacturing a ceramic circuit board obtained by laminating green sheets with different compositions. To form a multilayer ceramic circuit board by laminating, integrating, and firing, two green sheets with different compositions are laminated, heated and pressed, and integrated to form a unit green sheet. Align and stack the sheet laminates,
The method for manufacturing a multilayer ceramic circuit board is characterized in that it is pressurized and then fired.

[Industrial application field]

The present invention relates to a method for manufacturing a multilayer ceramic circuit board that suppresses the occurrence of peeling.

Due to the need to quickly process large amounts of information, information processing devices are becoming smaller and larger in capacity, and the devices are becoming more compact and large in size.
High-density packaging is being carried out by closely mounting semiconductor elements such as.

Initially, multilayer printed wiring boards made of glass epoxy or the like were used for the circuit boards on which these semiconductor elements were mounted, but as the degree of integration of semiconductor elements improved, the amount of heat generated increased, and the heat generated by one chip increased. As the amount exceeds IOW, ceramic substrates with excellent heat resistance have come to be used.

[Conventional technology]

Initially, alumina (Al) was used as a constituent material for ceramic substrates.
2O2) Ceramics were used, and tungsten (W) was used as the metal material to form the wiring pattern, but with the increase in the speed of information processing, the signal frequency has increased to MHz.
As the technology expanded to include light, low-loss ceramic substrates and low-resistance conductive materials became necessary.

Here, the preferred metal for low resistance conductor material is copper (Cu).
However, the melting point is as low as 1084℃, and the firing temperature is 140℃.
It cannot be used for alumina ceramics whose temperature exceeds 0℃.

Therefore, glass ceramics began to be used.

In other words, for glass ceramics, the firing temperature is 1000℃.
Therefore, a metal material with excellent conductivity such as gold (Au) or Cu can be used.

Typical glass ceramics are made by adding alumina powder to borosilicate glass as a solid solution, and since borosilicate glass has a low dielectric constant of about 4, the composite dielectric constant is 5 to 7, which is higher than alumina powder. It is smaller than about 10 mm for ceramics (therefore, the signal delay time can be reduced, which is advantageous).

However, the mechanical strength of glass ceramics, such as bending strength, is 150 to 200 MPa, which is weaker than that of alumina ceramics (there is a problem that they are easily damaged).

Therefore, in a glass-ceramic multilayer board, the signal layer on which the signal lines are patterned is made of glass-ceramic, while the ground layer and other parts that have little effect on signal quality are made of glass-ceramic with a low glass content or alumina powder. Instead, it is made of glass ceramic using other ceramic powder to increase its strength.

However, when a glass-ceramic multilayer substrate is formed using different materials in this way, there is a problem in that delamination is likely to occur because the shrinkage rates of each green sheet are different during firing.

[Problem to be solved by the invention]

BACKGROUND ART Circuit boards used in information processing devices such as large, ultra-high-speed computers that perform high-speed calculations must have excellent heat resistance, low signal delay time, and excellent mechanical strength.

Therefore, attempts have been made to form the signal line portion using glass ceramics with low loss, while forming the portions that have less influence on the electrical characteristics using glass ceramics with excellent mechanical strength.

However, the problem is that delamination tends to occur due to the different shrinkage rates of the green sheets during firing, and the problem is how to solve this problem.

[Means to solve the problem]

The above problem involves laminating ceramic green sheets with different compositions, integrating them, and firing them to form a multilayer ceramic circuit board. This problem can be solved by forming a green sheet, aligning and stacking the unit green sheet laminate, applying pressure, and then firing to form a multilayer ceramic circuit board.

[Effect]

The inventor studied the conditions under which delamination occurs in a multilayer ceramic circuit board obtained by alternately laminating different types of green sheets, applying pressure, and firing, and as a result, the following was clarified.

(2) In a glass ceramic substrate with a relatively small area such as 50 m + n square, peeling will not occur even if about 50 layers are laminated.

■ Even on a large-area glass-ceramic substrate such as 150 mm square, peeling is unlikely to occur up to about 20 layers.

In other words, when the temperature is gradually raised to a high temperature of about 1000 degrees Celsius, do different types of green sheets tend to peel off due to their different shrinkage rates?
Since 600°C borosilicate glass is used as a common material, the shrinkage rates are different.As a result of fusion of the borosilicate glass powders, peeling does not occur easily.

It was also found that peeling occurs at locations where the adhesion between the green sheets is incomplete.

That is, after the green sheets are aligned and stacked, they are heated to about 100°C and heated to about 300 kg/cm2.
However, at this time, the pressure was not necessarily applied uniformly over the entire area of the green sheet, and it was assumed that the source of the peeling was in areas where this pressure was weak and the adhesion was not sufficient. .

According to this estimation, the number of weak points increases in proportion to the area of the green sheet and the number of laminated layers, making peeling more likely (this is consistent with the experimental results).

Therefore, as a method of suppressing the occurrence of weak points, the present invention prepares the necessary number of clean sheets of different types that are laminated and integrated by heating and pressing, and after aligning and laminating them, The pressure distribution can be made uniform by integrating the laminates by heating and pressurizing them as in the conventional method, and by heating this laminate, the occurrence of peeling is significantly reduced compared to the conventional method.

[Example] Creation of green sheet A: Alumina powder and borosilicate glass powder in a weight ratio of 50
10% by weight of polyvinyl butyral (abbreviated as PVB) as a binder and 50% by weight of acetone as a solvent were added thereto, and these were mixed using a hole mill to prepare a slurry.

Then, it is molded using the doctor blade method and the size is 150mm.
A green sheet having a square mm square and a thickness of 200 μm was formed.

Preparation of Green Sheet B Mix dimulite powder and borosilicate glass powder at a weight ratio of 20
: Mix 80% and add 10% PVB as a binder to this.
Add 50% by weight of acetone as a solvent, mix this using a ball mill to make a slurry, and form it using a doctor blade method to form a green sheet with a size of 150 mm square and a thickness of 200 μm. Formed.

After aligning the green sheet A and the clean sheet B, they are integrated by applying pressure at 70°C and 2 MPa, and a via hole with a diameter of 90 μm is punched at a desired position in this bonded body. Embed Cu paste using screen printing method and print a width of 1 on the green sheet.
A wiring pattern with a thickness of 30 μm and 00 μm was formed.

Next, 50 such green sheet laminates were aligned and laminated, and they were pressurized and integrated under conditions of a temperature of 150° C. and a pressure of 40 MPa to form a laminate.

This laminate was fired at 1000° C. for 4 hours in a N2 atmosphere to obtain a multilayer ceramic circuit board, but no peeling phenomenon was observed.

In addition, a similar prototype was made for Green Sheet A using barium titanate (BaTiOs) powder instead of alumina powder and laminated with Green Sheet B to form a multilayer ceramic circuit board. , no peeling phenomenon was observed.

It is possible to manufacture multilayer ceramic circuit boards with good mechanical properties at a high manufacturing yield.

〔Effect of the invention〕

Claims (1)

[Claims] Laminated ceramic green sheets with different compositions,
When integrating and firing to form a multilayer ceramic circuit board, two green sheets with different compositions are laminated, heated and pressed to integrate to form a unit green sheet, and then the unit green sheet laminate is 1. A method for manufacturing a multilayer ceramic circuit board, which comprises aligning and stacking, applying pressure, and then firing.