JPS6273796A - Multilayer ceramic circuit substrate - 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 (Field of Industrial Application) The present invention relates to a multilayer ceramic substrate, particularly a highly thermally conductive multilayer ceramic substrate using vanadium nitride as a conductor.

(Prior art and its problems) With the dramatic progress in semiconductor technology, ICs and LSIs have come to be widely used for industrial and civilian purposes.

In particular, multilayer ceramic substrates are attracting attention as substrates for mounting L1s with high integration density and high-speed operation. This multilayer ceramic substrate can directly mount an LSI, and allows fine multilayer wiring.

Generally, alumina is used as a material for ceramic substrates, but in recent years, electrical equipment has become even more compact, and there is a strong demand for higher circuit densities.

The degree of integration of elements and circuit elements per unit area of the board is increasing. On the other hand, in the case of LSI chips, there is a tendency for a large amount of ripening to occur from the chip as the chip is operated from a distance. As a result, the amount of heat generated by the substrate increases significantly, resulting in the problem that the alumina substrate does not have sufficient heat dissipation. Therefore.

There was a need for an insulating substrate with higher thermal conductivity and better heat dissipation than alumina substrates, so a ceramic substrate mainly composed of silicon carbide was developed as a material with excellent heat dissipation. (Japanese Unexamined Patent Publication No. 180006/1983). Silicon carbide itself electrically belongs to a semiconductor, has a specific resistance of about 1 to 10 Ω·min, and has no electrical insulation properties, so it cannot be used as an insulating substrate.

In addition, silicon carbide has a high melting point and is extremely difficult to sinter.
Normally, sintering is carried out by adding a sintering aid with a small amount and using a so-called hot press method in which the sintering agent is pressurized at high temperature. When beryllium oxide or boron nitride is used as this sintering aid, it not only has the effect of the sintering aid but also 'r! L gas insulation is also effective, and the specific resistance of the sintered substrate mainly composed of silicon carbide is 100.
・It becomes more than α.

However, the dielectric constant, which is one of the important factors in mounting boards such as LSI, is quite high at 40 at IMHz, and even with the addition of additives, the insulation between particles decreases rapidly when the voltage reaches about 5V. Therefore, there is also a problem with the withstand voltage.

Furthermore, although it is possible to create a multilayer ceramic substrate using BeO powder, it is difficult in practice due to its toxicity.

On the other hand, from a process point of view, a hot press method must be applied, which not only increases the size of the apparatus, but also makes it difficult to increase the shape of the substrate, and there are many problems with surface smoothness. For ceramic substrates using smooth silicon carbide threads, it is extremely difficult to use alumina multilayer ceramic substrate technology using the conventional green sheet method.

The green sheet multilayer ceramic substrate technology referred to herein is the following technology. First, ceramic powder is mixed with an organic vehicle to form a slurry. A sheet having a thickness of about 10 μm to 400 μm is formed on an organic film by casting this slurry. After cutting the sheet into a predetermined size and forming through holes for establishing electrical conduction between each layer, a predetermined conductor pattern is formed by thick film printing. Ceramic green sheets laminated and pressed to form each of these conductor patterns,
After one step of de-pindering, it is fired.

The main characteristics that a high-density mounting board should have are (
1) Low dielectric constant with respect to electrical properties, low dielectric loss, and excellent electrical insulation, (2) Sufficient mechanical strength, (3) High thermal conductivity, ( 4)
The coefficient of thermal expansion is close to that of silicon chips, etc. (
5) It must have excellent surface and smoothness, and (6) It must be easy to increase the density.

The above-mentioned ceramic substrates cannot be said to be sufficient in terms of these substrate properties in general.

On the other hand, aluminum nitride has been developed as a material for highly thermally conductive substrates (Japanese Patent Laid-Open No. 59-50077, etc.)
. However, this material also has to be sintered at high temperatures, and the mainstream tabulation method is the hot press method.
A multilayer wiring board using aluminum nitride has not yet been realized.

(Objective of the invention) The present invention has excellent thermal conductivity, high density conductor of 8M inside,
An object of the present invention is to provide a multilayer ceramic substrate with high thermal conductivity.

(Structure of the Invention) According to the present invention, there is provided a highly thermally conductive multilayer ceramic wiring board characterized in that the ceramic layer is composed of a polycrystalline body containing aluminum nitride as the main component, and the conductor layer is composed of vanadium nitride as the main component. can get.

Solved the problem.

First, aluminum nitride, which has high thermal conductivity, was used as the insulating ceramic material constituting the multilayer ceramic substrate. After firing, this material forms a dense structure of polycrystalline aluminum nitride. In order to obtain high thermal conductivity, it is preferable that the amount of oxygen contained in the sintered body is small, and therefore it is preferable to add a reducing agent having a reducing effect as an additive.

Next, regarding the conductor layer, multiple conductor layers such as a power supply layer, a ground layer, and fine signal lines are formed on a ceramic layer made of aluminum nitride, and these multiple conductor layers are provided in the ceramic layer. It is electrically connected via a peer hole.

Therefore, the wiring density of the mounting board can be greatly increased, and the heat generated from elements such as LSI can be efficiently dissipated to the outside.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory view showing an embodiment of the sieve heat conductive multilayer ceramic substrate according to the present invention. Reference numeral 1 denotes an insulating ceramic layer, which is mainly composed of polycrystalline aluminum nitride. 2 is a conductor layer for signal lines, power supply, etc.;
It is formed mainly of vanadium nitride, and the layers are electrically connected through peer holes 3 formed in the insulating ceramic layer. The die pad 4 and the main board are arranged so that the uLsl chip can be mounted on the multilayer ceramic substrate having this structure.

A board 5 is formed to take out signals outside the mounting board,
Pad for entering and exiting blades 6 for inserting No. 100 into the board
is formed on the back side of the board. Heat generated from the LSI chip mounted on the substrate is diffused into the ceramic substrate via the tie pad 4. Due to the high thermal conductivity of the ceramic substrate, heat diffusion is carried out efficiently, and it is possible to prevent the heat generation of the LSI chip from increasing in temperature. It is as follows. Ceramic materials constituting the substrate of the present invention include:
C as an additive to improve the sinterability of aluminum nitride
Contains aC2. First, aluminum nitride powder and CaC2 powder were weighed and wet mixed in an organic solvent using a ball mill for a total of 48 hours.

This mixed powder is dispersed in a solvent (with a viscosity of 3,000 to 7
Create a slurry in the range of 000ep. A green sheet is formed on an organic film using the slurry casting method so as to have a uniform thickness of about 10 μm to 200 μm.

Next, after peeling off the green sheet using an organic film, pier holes are formed to electrically connect each layer. The peer hole formed here is mechanically connected to the
Although it was punched out using a chip and a die, it is also possible to open it using other methods such as laser processing.

A conductive paste mainly composed of a vanadium compound, which becomes vanadium nitride when fired in a nitrogen atmosphere, other neutral atmosphere, or halide atmosphere, is applied onto the green sheet with peer holes in a predetermined shape by screen printing. A predetermined pattern is printed on the position f. A desired number of green sheets having conductors printed thereon are laminated and hot pressed.

Thereafter, it is cut into the required shape ζ using a cutter and fired in a non-oxidizing atmosphere at a temperature of 1400°C to 2000°C. During firing, the temperature rises from 400℃ to 60℃.
The binder was sufficiently removed at a temperature of 0°C.

The characteristics of the fabricated substrate are shown in the table.

VN, V)L VF3 and VCC20 were used as conductor paste materials.

The amount of CaC2 shown here is a value when aluminum nitride is taken as 100. Also, the value is based on the weight ftl, which is the frit amount plus the conductor material and the frit material.

As a result of measuring the electrical characteristics of the created board, the specific resistance was
o 11 Ω, □ or more, dielectric constant 8.7 (1MHz), dielectric loss less than fllXlO (1MHz)
Met. It can be seen that the electrical characteristics are also at least the same as those of conventional boards, and are sufficient as a mounting board.

On the other hand, as additives for aluminum nitride, Cab, Be0
5Y203. Cub, Age, BaCz, 5r
C2, Na2C2, K2C2, CuC2, MgC2, A
Even when gC2, ZrCz, etc. were used, the effect of improving the sinterability of the alumina nitride substrate was obtained.

(Effects of the Invention) As is clear from the examples, the multilayer ceramic wiring board of the present invention can easily form a high-density circuit having conductors including signal lines and power supply layers, and has excellent heat dissipation. A highly thermally conductive multilayer ceramic substrate is obtained which is very effective in terms of temperature and temperature.

The thermal conductivity of the conventionally used alumina substrate is 17W/
It can be seen that the thermal conductivity of the substrate of the present invention is at a very high level. In addition, the thermal expansion coefficient of the alumina substrate is 65X]OIc, whereas the substrate of the present invention has a small value, which is advantageous because it is closer to the thermal expansion coefficient of a silicon chip.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a highly thermally conductive multilayer ceramic substrate showing an embodiment of the present invention. I...-Insulating Lamic Layer, 2...Conductor Layer, 3...Pier Hole.

Claims (1)

[Claims] A multilayer ceramic wiring board comprising a ceramic layer containing aluminum nitride as a main component and a conductor containing vanadium nitride as a main component.