JPH04314393A - Manufacture of multi-layer ceramic circuit board and lamination structure - Google Patents

Abstract

PURPOSE:To prevent separation between board layers in the production method of a ceramic circuit board which is realized by laminating green sheets of different compositions. CONSTITUTION:A ceramic material with a low dielectric constant is used for the signal layers 2, 3 which constitute a multilayer board, a ceramic material with a large bending strength is used for the reinforcing layers 5, 6 which are positioned above and below the multilayer board, and after laminating the green sheets made of these materials, these layers are compressed together. In the multilayer board obtained by unifying and sintering these layers, it is possible to establish similar ratios of the contraction which occurs in the sintering process for the two materials by adjusting the specific surface area and thereby achieve a multilayer 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 for manufacturing a multilayer ceramic circuit board in which peeling is suppressed. Due to the need to quickly process large amounts of information, information processing devices are becoming smaller and larger in capacity, and devices are densely packed with semiconductor elements such as LSI and VLSI.

[0002] Initially, multilayer printed wiring boards made of glass epoxy or the like were used as 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. The heat value of the chip is 1
Ceramic substrates with excellent heat resistance have come to be used as power exceeds 0W.

0003

[Prior Art] Alumina (Al2O3) ceramics was initially used as a constituent material for ceramic substrates.
In addition, tungsten (W) was used as the metal material for forming wiring patterns, but as information processing speeds up, signal frequencies reach the order of MHz, and optical communications also become available, low-loss ceramic substrates are being used. This created a need for low-resistance conductor materials.

[0004] The preferred metal for the low resistance conductor material is copper (Cu), but its melting point is as low as 1084°C.
Alumina whose green sheet firing temperature exceeds 1400℃
It cannot be used as a wiring material for multilayer circuit boards made of ceramics.

[0005] Therefore, glass ceramics with low firing temperatures have come to be used. In other words, glass ceramics can be fired at a temperature of 1000°C or less,
Therefore, a metal material with excellent conductivity such as gold (Au) or Cu can be used.

[0006] Typical glass ceramics are made by adding alumina powder to borosilicate glass as a solid solution, and since the dielectric constant of borosilicate glass is as low as about 4, the composite dielectric constant is 5 to 5. 7 is smaller than that of alumina ceramics, which is about 10, which is advantageous in that the signal delay time can be shortened.

However, there is a problem in that the mechanical strength of glass ceramics, for example, bending strength is 150 to 200 MPa, which is weaker than that of alumina ceramics and easily breaks. Therefore, in a glass-ceramic multilayer board, the signal layer on which the signal lines are patterned is made of glass-ceramics, while the top and bottom layers, which have little effect on signal quality, are made of glass-ceramics with a low glass content. , mullite (3 Al2O3 ・2 SiO2)
In order to increase the strength, it is made of glass ceramics using ceramic powder with excellent mechanical strength.

However, when forming a glass-ceramic multilayer substrate using different materials in this way, delamination is likely to occur due to the different shrinkage rates of each green sheet during firing, and this tendency tends to occur when the substrate area is large. It is becoming more and more noticeable. That was the problem.

[0009]

[Problem to be solved by the invention] A large-scale computer that performs high-speed calculations
Circuit boards used in information processing devices such as ultra-high-speed computers need to have excellent heat resistance, low signal delay time, and excellent mechanical strength.

[0010] Therefore, attempts have been made to form the signal line portion using low-loss glass ceramics, while forming the portions that have little effect on 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 to solve this problem.

[0011]

[Means for solving the problem] The above problem is solved by using a ceramic material with a low dielectric constant for the signal layer constituting the multilayer board.
In addition, a ceramic material with high bending strength is used for the reinforcing layers placed on the top and bottom of the multilayer board, and in a manufacturing method in which green sheets made of this material are laminated, pressed, integrated, and fired, the ceramic material used is This problem can be solved by configuring a method for manufacturing a multilayer ceramic circuit board characterized by adjusting the specific surface area to approximate the shrinkage rates of both during firing.

0012

[Operation] When firing glass ceramics, the present invention
If the specific surface area of the raw material powder is large, the porosity in the green sheet is high, resulting in a large shrinkage rate during firing, while if the specific surface area is small, the porosity is low, so the shrinkage rate is small. This approximates the shrinkage rates of the signal layer and the reinforcing layer.

FIG. 1 is a sectional view showing a method of carrying out the present invention. When a multilayer ceramic circuit board is composed of five layers, the green sheets of the second layer 1, third layer 2 and fourth layer 3 are A signal wiring 4 is patterned on the third layer 2 and the fourth layer 3 by forming them from glass ceramic with a low dielectric constant.

On the other hand, the green sheets of the first layer 5 and the fifth layer 6 are formed of glass ceramics having excellent mechanical strength to serve as reinforcing layers. Then, a ground layer (shield layer) 7 is patterned on the second layer 1 and the fifth layer 6, aligned, pressed together, and fired to complete a multilayer ceramic circuit board.

However, in most cases, the reinforcing layer (first layer 5 and fifth layer 6) and the low-k glass-ceramic layer (low-k glass-ceramic layer) have different shrinkage rates during firing. Cracks occur between the layers (second to fourth layers), and if the area is large, peeling occurs.

Therefore, in the present invention, a reinforcing layer with a small shrinkage rate is formed using ceramic powder with a large specific surface area, and a low dielectric constant glass-ceramic layer with a relatively large shrinkage rate is formed with a ceramic powder with a small specific surface area. It is formed by

[0017]

[Example] Specific surface area is 1.2 m as ceramic powder
2/g and 3.8 m2/g of mullite (3 Al2O3
・2SiO2) was prepared.

Mullite with a specific surface area of 1.2 m2/g was used for the low dielectric constant glass ceramic layer, and mullite with a specific surface area of 3.8 m2/g was used for the reinforcing layer. That is, the structure of the low dielectric constant glass-ceramic layer includes 30 parts by weight of borosilicate glass powder and 60 parts by weight of silica glass powder.
〃Mullite powder ・・・・・・・・・・・・10
On the other hand, the structure of the reinforcing layer is as follows: borosilicate glass powder 30 parts by weight silica glass powder 40
Mullite powder ・・・・・・・・・・・・30
〃And as the binder and solvent, the binder (
Polyvinyl butyral)...50 parts by weight Plasticizer (dibutyl phthalate)...15 Solvent
(Ethanol) ・・・4
00 were used in common, and each was mixed using a ball mill to make a slurry, which was molded using a doctor blade method to form a green sheet with a thickness of 200 μm and a size of 150 mm.

[0019] Next, 15 of these green sheets were laminated and integrated by applying pressure at 150° C. and 10 MPa, and then baked at 1000° C. for 4 hours in a N2 stream to produce a substrate. When the shrinkage rates of these substrates were measured, they were both 18.0%, the dielectric constant of the low dielectric constant glass ceramic layer was 4.1, and the bending strength of the reinforcing layer was 160%.
It was MPa.

Next, copper (Cu) paste is screened on the low dielectric constant glass ceramic green sheet and the reinforcing layer green sheet to form a pattern for signal wiring and a ground layer, and after drying, the layers are laminated as shown in FIG. and 150℃,
After pressurizing and integrating under the conditions of 10 MPa, the ceramic multilayer circuit board was formed by firing at 1000° C. for 4 hours in a N2 stream, but no cracks were observed.

[0021]

[Effects of the Invention] By carrying out the present invention, even if a multilayer board is formed by laminating a low dielectric constant glass ceramic green sheet and a reinforcing layer green sheet, cracks and peeling will not occur, and this will improve the electrical and mechanical properties. It becomes possible to put into practical use a ceramic multilayer circuit board that has both of these features.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a ceramic multilayer circuit board.

[Explanation of symbols]

4 Signal wiring 7 Ground layer

Claims (2)

[Claims] Claim 1: A ceramic material with a low dielectric constant is used for the signal layer constituting the multilayer board, and a ceramic material with high bending strength is used for the reinforcing layers disposed above and below the multilayer board,
In a multilayer substrate formed by laminating green sheets made of the above materials, pressurizing them, integrating them and firing them, the shrinkage rates of both ceramic materials that occur during firing can be approximated by adjusting the specific surface area of the ceramic material used. A method for manufacturing a multilayer ceramic circuit board. 2. In a ceramic laminate structure formed by stacking green sheets made of ceramic materials, pressurizing them, and then integrating and firing them, a ceramic layer with a small shrinkage rate is formed using ceramic powder with a large specific area, A ceramic laminate structure characterized by forming a ceramic layer with a high shrinkage rate using ceramic powder with a small specific surface area.