JPS6276597A - 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 (Industrial Application Field) The present invention relates to a multilayer ceramic wiring board.

(Prior art and its problems) Due to the rapid progress of semi-isolated technology, ICs and LSIs are becoming widely used for industrial and civilian purposes.

In particular, multilayer ceramic substrates are attracting attention as mounting substrates for high-speed operation LSIs with high integration density. LSI can be directly mounted on this multilayer ceramic rough substrate Vi, and fine multiple wiring is possible.

Alumina is generally used as a material for ceramic substrates, but in recent years electrical devices have become smaller 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 high.
-6. On the other hand, as LSIs operate at high speeds, the heat generated from the chips tends to increase. As a result, the heat generated by the circuit board increases significantly.
A problem with alumina substrates is that they do not have sufficient thermal grazing properties. Part 1.

Thermal conductivity is greater than that of alumina substrates, allowing for heat grazing. An insulating base plate with excellent properties has become necessary.

Therefore, a ceramic substrate containing silicon carbide and P as main components was developed as a material with excellent heat dissipation properties (Japanese Patent Application Laid-Open No. 180006/1983). Silicon carbide itself is an electrical semiconductor with a specific resistance of 1 to 10 Ω・c
Since there is no electrical strength at about 5 degrees, the insulating substrate and 1. I can't use it. In addition, because silica has a high axial rotation and is very difficult to sinter, it is usually produced by the so-called hot press method in which a small amount of sintering aid is added during sintering and pressurized at high temperature. When oxide or boron nitride is used as a sintering aid, it is effective not only for the sintering aid but also for electrical insulation, and the specific resistance of the sintered substrate mainly composed of silicon carbide is 10Ω.・It becomes more than α. However, the 11! The power rate is high, 40 at 1 MHz, and even with additive-added insulation, when the voltage reaches about 5 V, the insulation between particles drops drastically, which also poses a problem with 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.

10,000 From a process point of view, the hot press method must be applied, and the equipment is large-scale.In addition, the shape of the substrate is difficult to increase to a large area, and the surface smoothness is difficult to achieve. However, there are many problems in the process.It is extremely difficult to use the conventional green sheet method to use the single alumina multilayer ceramic substrate technology for ceramic substrates using silicon carbide. The sheet method multilayer ceramic substrate technology is as follows: First, ceramic powder is mixed with an organic material and a vehicle.
Make slurry. A sheet 8 having a thickness of about 10 μm>400 μm is formed by casting this slurry.
- Formed on an organic film. After cutting the sheet into predetermined large holes and forming through holes for obtaining electrical conduction between each layer, a predetermined conductive pattern is formed by thick film printing. The ceramic clean sheets on which each of these conductor patterns have been formed are laminated and pressed, subjected to a binder removal step, and then fired.

□d is the main characteristic that should be possessed as a basis for density mounting.
(1) Low diN1, low dielectric loss, and excellent electrical insulation properties, (2) Sufficient mechanical strength, and (3) High thermal conductivity. ,
(4) The coefficient of thermal expansion is close to that of silicon chips, etc., (5) The surface smoothness is excellent, and (6)
It is necessary that the density can be increased easily.

It cannot be said that the above-mentioned ceramic base is sufficient for the overall properties of these substrates.

On the other hand, aluminum nitride has been developed as a material for highly thermally conductive substrates (Japanese Unexamined Patent Publication No. 59-50077, etc.)
. However, this material cannot be sintered at high temperatures, and the manufacturing method that relies on hot pressing has become popular. (Objective of the Invention) The present invention eliminates the drawbacks of the conventional ceramic MEC gland wiring board mentioned above, and provides a high-temperature structure with a conductor inside, which has excellent thermal conductivity. (Structure of the Invention) According to the present invention, the ceramic structure is composed of a polycrystalline body mainly composed of aluminum nitride, and A highly thermally conductive multilayer ceramic wiring board is obtained, the main component of which is a mixture of two or more metal nitrides.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by adopting the above-mentioned configuration.

1. Aluminum nitride, which has high thermal conductivity, is used as the insulating ceramic material for the groove bottom of the multi-row ceramic substrate. 2. After firing, this ceramic material forms a dense structure of polycrystalline aluminum nitride. In order to obtain thermal conductivity, it is preferable that the amount of organic oxygen in the sintered body is small, and therefore it is preferable to add a reducing agent having a reducing effect as an additive.

Regarding the conductor layer, there are multiple power supply layers, ground layers, and 4J! ceramic layers coated with aluminum nitride. A conductor layer such as a thin signal line is formed, and these conductor layers are electrically connected through peer holes provided in the ceramic layer.

Therefore, the wiring density of the mounting board is very high by one (Embodiment) Embodiment F of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of a highly thermally conductive multilayer ceramic wiring board according to the present invention. This is an IH insulating ceramic layer, and the main component is polycrystalline aluminum nitride. 2 is a conductor layer for signal lines, power supply, etc., which is formed mainly from a mixture of two or more metal nitrides, and has a pier hole 3 formed in an insulating ceramic layer.
Four electrical connections are made between each layer via the . On the multilayer ceramic substrate configured in this way, 1LsI chip,
ζ die pad 4 and bonding panod 5 are formed so that 1 can be mounted, and 7 input/output pads 6 are formed to take out Ig from the mounting board and input/output signals into the board. It has a tatami surface. Heat generated from the LSI chip mounted on the substrate is diffused into the ceramic substrate via the die pad 4. The high thermal conductivity of the ceramic substrate allows for efficient heat diffusion and prevents the LSI chip from increasing in temperature due to heat generation.

The method for manufacturing the wiring board of this example is as follows. As for the ceramic material constituting the substrate of the present invention,
C is added as an additive to improve the sinterability of aluminum nitride.
Contains aCJ. First, aluminum nitride powder and C:qCJ powder were weighed and wet mixed in an organic solvent using a ball mill for 48 hours.

This mixed powder is dispersed in a solvent with an organic binder that is easily decomposed in a neutral atmosphere, such as polycaprolactone or polyacrylate resin, and the viscosity is 3000-70.
Creates a slurry in the range of 00 cp. The slurry is cast onto an organic film to form a green sheet so as to have a uniform thickness of about 10 to 200 μm using a casting film forming method.

Next, after peeling this green sheet from the organic film, pier holes are created to electrically connect each layer. The pier holes formed here were punched out mechanically using a punch and die, but they can also be punched out by other methods such as laser machining.

Pier holes are formed on the tag green sheet.

A conductor paste whose main component is a compound that becomes a mixture of two or more metal nitrides when fired in an ambient atmosphere or other neutral atmosphere or in a reducing atmosphere is printed on a predetermined area using a screen printing method. Print a predetermined pattern. A desired number of green sheets having conductors printed thereon are laminated and hot pressed.

Thereafter, it is cut into the required shape using a square cutter and fired in a non-oxidizing atmosphere at a temperature of 1400°C to 2000°C. During firing, the temperature rises to 400°C to 6.
The binder was sufficiently removed at a temperature of 00°C. The composition of the conductive paste used in the prepared sample f is shown in Table 1, and Table 2 shows the characteristic values of the sample.

NbN, TaN, VN, Zr, and T1 were used as conductor paste materials.

The residue of the additive (CaC2) shown here is the saliva when aluminum nitride is taken as 100. Also, the frit weight is the value relative to the combined weight of the conductor material and frit material.
S6゜As a result of measuring the electrical characteristics of the created board, the specific resistance was 1
It is more than 0 Ω・I, and the visiting rate is 87 (1 MHz)-
ijN! The loss was less than lXl0 (I MHz:).The electrical characteristics (here, too, it was on the same level or higher than that of the conventional board, and was sufficient for a mounting board).BaCz, 5
rCz, NatCz, K2O)l, CuCz, MgC2
, Agz(J, ZrCz, etc.) also had the effect of improving the sinterability of aluminum nitride.

(Effects of the invention) As is clear from the examples (this invention is easy to use)
It is possible to form a high-density circuit with conductors including signal lines and power supply layers, and the heat dissipation rate is 31%.
The thermal conductivity of the conventionally used alumina substrate is +7W/
The thermal conductivity of the substrate of the present invention is 65×10 7 ”C, whereas the thermal conductivity of the substrate of the present invention is 65×10 7 ”C, whereas the substrate of the present invention has a small thermal conductivity.

This is advantageous because the coefficient of thermal expansion is closer to that of a silicon chip.

[Brief explanation of drawings]

Claims (2)

[Claims] (1) A multilayer ceramic wiring board in which a conductor is formed three-dimensionally through a ceramic layer, which has a ceramic layer mainly composed of aluminum nitride and a conductor mainly composed of a mixture of two or more metal nitrides. A multilayer ceramic wiring board characterized by: (2) The multilayer ceramic wiring board according to claim 1, wherein the metal nitride is titanium nitride, zirconium nitride, vanadium nitride, tantalum nitride, or niobium nitride.