JPS59101889A - High thermoconductive composite heat sink 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] [Technical field of invention] The present invention relates to a heat dissipating substrate with high thermal conductivity.

[Technical background of the invention and its problems]

In recent years, in the field of electronic equipment and semiconductor equipment, miniaturization,
As performance increases, effective heat dissipation from circuit components has emerged as an important issue, and therefore there is a strong desire to develop insulating materials with excellent heat dissipation properties.

Until now, various types of ceramics have been used as such insulating materials; for example, AQ203 has been the mainstream mainly used in IC substrates, and BeO has also been used.

However, Ag, 203 has a limited thermal conductivity (maximum approximately 0.3 W/crn-U), making it impossible to sufficiently enhance its heat dissipation properties, and BeO is a toxic substance. Ta.

Recently, SiC-
BeO-based materials have been developed (see JP-A-56-66086, JP-A-57-2591, JP-A-57-15484, etc.), but this material has varistor properties and cannot be used under high voltage. However, it is inconvenient because BeO, a toxic substance, is used in the manufacturing process.

On the other hand, AQN has appeared as a new material, but it has excellent electrical insulation properties and a dielectric constant of 8 to 9, and theoretically has a thermal conductivity close to that of BeO. It is the material. However, in reality, the incorporation of impurities such as oxygen or the formation of foreign phases is unavoidable during the manufacturing process, and as a result, the thermal conductivity decreases, currently 0.6 W/cm.
-C is the highest value. Therefore, the heat dissipation characteristics are approximately 2
．． Be01 of 5W/Crn-C approximately 2.3 W/cm −
It is smaller than C metal 1.

As described above, since the conventionally known highly thermally conductive ceramics each have advantages and disadvantages, there is a desire for a material that has even better heat dissipation properties and high electrical insulation properties.

[Purpose of the invention]

The present invention can meet the above industrial demands,
The purpose is to provide a heat dissipation board with excellent heat dissipation characteristics and electrical insulation.

[Summary of the invention]

The present inventors discovered that AQN has excellent electrical properties but inferior heat dissipation properties, and that SiC has high thermal conductivity and excellent heat dissipation properties, but low electrical resistance and lacks suitability as an insulating material. Focusing on the fact that the coefficients of thermal expansion of both are close to each other, he got the idea that by stacking layers of both, the excellent properties of both could be utilized independently, and he conducted extensive research. As a result, we have developed the composite substrate of the present invention, which has excellent heat dissipation properties and can function satisfactorily electrically.

That is, the heat dissipation substrate of the present invention is a laminate of an AQN layer and a SiC layer, and in another embodiment, AαN
It is characterized by being a laminate in which a mixed layer of SiC and SiC is interposed.

The composite heat dissipation board of the present invention can be manufactured, for example, as follows.

First, the first method is AQN, SiC, IN and Si
A method of molding or sintering the mixed powder of C according to a conventional method to form a green compact or sintered plate of a predetermined thickness, and then laminating these and hot pressing them to bond them together to form an integral laminate. be.

The second method involves adding kQN, S i
C.

This is a method in which mixed powders of AQN and 8iC are filled to a predetermined thickness, and the whole is hot pressed and sintered as one piece.

The third method is to use a SiC sintered plate of a predetermined thickness or a
In this method, AQN is sputtered by a conventional method onto a sintered plate on which a mixed layer of QN and SiC is formed, and AAN is integrally laminated thereon.

Here, the mixed layer is an AQN layer and a SiC layer bonded on both sides.
It functions to buffer the generation of thermal stress due to the difference in thermal expansion between the layers, and the mixing ratio of AQN and 8+C can take various values depending on the temperature distribution acting on the substrate during use. Usually, the mixing ratio is 20 to 80 by weight.
within the range of %. Moreover, this mixed layer is composed of AQN and Si.
It may be a layer in which AQN and 8iC are uniformly mixed at a predetermined mixing ratio, but depending on the situation, the mixing ratio of AQN and 8iC may be varied in stages to give a slope to the coefficient of thermal expansion of the mixed layer. It may be a layer.

[Embodiments of the invention]

Example 1 SiC powder with an average particle size of 1 μm was mixed with 2 wt% B4C and 2 wt% C powder, and this mixed powder was heated in a vacuum.
2000 tons? T-sintered to a density of 3-15 P/Cm”
(7) A SiC sintered plate was prepared. Thickness approximately 1-51ar ++
(7) Place the SiC sintered plate in the carbon mold, and place F8SS (Fisher's 5ub-
8ieveSize) AQN with particle size 1.2jjm
An AQN powder compact (thickness 1.5n+m) formed by molding powder at a pressure of 50 okt/Cm was placed on it, and the whole was heated in a vacuum for 18
Hot pressed at 00C, 3ooky/m2 at Token.

A composite substrate in which an AgN layer and a SiC layer were bonded was obtained.

When the cut section of the joint of this composite substrate was observed using an X-ray microanalyzer, a metallurgical microscope, and a scanning electron microscope, it was found that the AQN layer and the SiC layer were clearly separated at the joint, but at the same time they were sufficiently bonded to each other. I was able to confirm that there was.

Next, both sides of this composite substrate were ground with a diamond grindstone to obtain a substrate having an AffiN layer thickness of 0.3 mm, a SiC layer thickness of 0.5 vm, and a total thickness of 0.8 m.

When the thermal conductivity of this substrate was measured by the laser flash method, it was 1.15 W/cm -7: and the thickness was 0.
The 8 m long iN substrate had a thermal conductivity of 0.5 W/Crn, and had a heat dissipation effect 2.3 times that of C. Note that the electrical insulation property was the same as that of AQN alone.

In addition, when the composite substrate of the present invention was manufactured by varying the thickness of AQ and N, and its heat dissipation characteristics were investigated, it was found that A, QN
The thinner the material, the better the results.

Example 2 AQN/5iC (
Example 1 was performed, except that a sintered plate (thickness: 0.2 trtm) of AQN-SiC mixed powder with a weight ratio of 1 was interposed, and the thickness of the AQN powder compact was 1 m. Similarly, an AQN-AQN/SiC-S i C composite substrate was manufactured.

When the bonded portion was observed in the same manner as in Example 1, it was confirmed that each layer was clearly separated and sufficiently bonded.

In addition, this composite substrate was ground with a diamond grindstone, and AQ
Thermal conductivity was measured in the same manner as in Example 1 with the N layer thickness 0.2 mm, the SiC layer thickness 0.4 mm, and the total thickness 0.8 mm. there were.

〔Effect of the invention〕

As is clear from the above description, the composite substrate of the present invention is
It has electrical insulation properties equivalent to AQN and excellent heat dissipation properties, making it particularly useful as high-output circuit boards such as power ICs.

1-1 East Komukai Toshiba-cho, Saiwai-ku, Kawasaki City Kyoshibaura Electric Co., Ltd. Research Institute

Claims (1)

[Claims] 1. A highly thermally conductive composite heat dissipation board characterized by being a laminate of an aluminum nitride layer and a silicon carbide layer. 2. A highly thermally conductive heat dissipating substrate characterized by being a laminate in which a mixed layer of aluminum nitride and silicon carbide is interposed between an aluminum nitride layer and a silicon carbide layer.