JPS593810A - Electronic material substrate adding agent - 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 The present invention relates to an electronic material substrate additive, particularly an electronic material substrate additive having high thermal conductivity and high insulation properties.

In recent years, various electronic materials and devices have been distributed, and along with the complexity and diversification of these materials, progress has been made in making them more compact.

In these situations, as various electronic circuits become more integrated, local heat generation in the circuits has a large impact on the performance of the circuits.
The degree of integration of a circuit is determined by its heat dissipation capacity.

For this reason, in the past, fairly bulky equipment was required, such as installing a thick copper plate on the back side of the integrated circuit to help dissipate heat, or installing fins or fans for the purpose of heat dissipation. It had drawbacks such as not being able to dissipate heat as expected.

There is also a method of encasing Kinho in glass, hoping for heat dissipation from the metal and insulation from the glass, but this also does not have very good performance.

Furthermore, there are silicone-based resins and epoxy-based resins mixed with high-purity alumina sintered powder or boron nitride sintered powder as a thermally conductive filler, but these also do not have very high thermal conductivity. No 0 In addition, there is a proposal to add high thermal conductivity and high electrical insulation by adding beryllium oxide or silicon nitride to silicon carbide as the main component and mixing this into a resin as a sintered powder. (Japanese Unexamined Patent Publication No. 56-16
(See Geiho No. 1461). However, since this method requires a sintered body, it is particularly difficult to use a sintered body of silicon carbide.
In addition, when beryllium oxide is used in conjunction with beryllium oxide, its toxicity becomes a problem, and industrial production must be subject to significant restrictions from the viewpoint of working environment and hygiene. There are disadvantages that cannot be avoided.

In addition, when silicon nitride is used instead of aluminum oxide, high temperatures are required for sintering silicon carbide, so some of the silicon nitride decomposes into nitrogen and silicon, impairing its insulation properties. There are drawbacks.

In view of these points, the present inventor conducted various studies and examinations with the aim of finding an additive for electronic material substrates that has high thermal conductivity and high insulation properties, and as a result, discovered that silicon carbide, which has a special form, It has been found that the above object can be achieved by using silicon nitride.

Thus, the present invention provides an electronic material substrate additive comprising crystal grains in which silicon carbide and silicon nitride are bonded, and the core is silicon carbide and the core is coated with silicon nitride.

In the present invention, if the particle size of silicon carbide that is the core is too large, there is a risk that local thermal conductivity will occur when it is mixed with a resin as described later. The appropriate particle size is generally about 10 μm or less.

Also, if the thickness of silicon nitride that is present in a form that covers this is too thin, the electrical insulation will be insufficient, and if it is too thick, the good properties of silicon carbide will be deteriorated. Both are unfavorable because thermal conductivity is substantially inhibited. Therefore, the thickness of silicon nitride is 5X10-'
It is appropriate to adopt a value of about .about.lμ.

There are several methods for manufacturing such a composite of silicon carbide and silicon nitride, but in particular, when manufacturing using the following method, it is possible to achieve high thermal conductivity and high electrical insulation. It is particularly preferred since it can be used as an additive that provides stable properties over a long period of time.

An inorganic silicon compound containing a halogen such as silicon tetrachloride is reacted with ammonia in a non-oxidizing atmosphere to synthesize an amorphous silicon sulfuride, and at the same time, active carbon is generated at the same time as this synthesis. By pre-existing a carbonaceous substance, amorphous silicon nitride is first formed surrounding active carbon with active carbon as a core. Next, the amorphous silicon nitride is heated in a non-oxidizing atmosphere to convert it into α-crystalline silicon nitride.

When this operation is performed, active carbon and partially amorphous silicon carbide react to form silicon carbide. Thus, by appropriately selecting the amount of carbonaceous material, the amount of silicon carbide produced can be controlled.

The halogen-containing inorganic silicon compound used in the present invention is
In addition to 5iC14, for example, 5iHC11, 5iH2CI□
.

5iH3C:1, SiBr4, 5iHBr3,
5iH2Br2.81H3Br.

S1 engineering, , Sin engineering 3. SiH2 engineering 2.5iH1
■, 5iC12Br2゜5iC12Engineering2, etc. Some of these are gaseous at room temperature, but others are liquid or solid, and in order to quickly carry out a uniform reaction, It is appropriate to gasify the mixture by heating or other means and then use it for the reaction.

The amount of ammonia used in the reaction is 0 molar ratio to the halogen-containing inorganic silicon compound used as a raw material.
．． It is appropriate to adopt numbers 1 to 6. If the amount of ammonia used is less than the above range, the reaction rate of the halogen-containing inorganic silicon compound will be low and unsuitable for industrial use.On the other hand, if it exceeds the above range, solid ammonium halide will precipitate and the reaction will be delayed. This is also undesirable because it is difficult to operate.

Among these ranges, a molar ratio of 0.5 to 5 is particularly preferred because the reaction can be carried out effectively and industrially advantageously.

Next, the carbonaceous substance used in the present invention is a substance that decomposes to produce active carbon at the stage where amorphous silicon crab is produced by the reaction between a halogen-containing inorganic silicon compound and ammonia. However, if such a carbonaceous material is not used, it is difficult to obtain an additive that exhibits high thermal conductivity and high insulation properties, which are the objects of the present invention.

Such carbonaceous substances are generally selected from among halogen-containing dihydrated or halogen-containing unsaturated hydrocarbons, or halogen-containing aromatic hydrocarbons, in which the number of hydrogen atoms is equal to or equal to the number of halogen atoms. Alternatively, two or more types can be used in combination.

Specifically, dichloroethylene and methyl chloride.

Methylene chloride, dichloroethane, trichloroethane, and vinyl chloride are suitable, and are particularly preferred because their conversion to silicon carbide is easy to control. As other means, although the operation is a little complicated, means such as blowing carbon itself such as carbon black powder into the reaction system at the stage of forming amorphous silicon nitride may also be adopted. In short, in the present invention, if an amorphous silicon nitride is prepared in advance and carbon is mixed therein, the object of the present invention cannot be achieved.

The amount of these carbonaceous substances to be used is selected so as to obtain the size of the silicon carbide core and the thickness of the silicon nitride layer covering it as described above. That is, it is appropriate to adopt a molar ratio of about 0.5 to 1.2 of the carbonaceous material to silicon in terms of carbon.

These raw materials are then allowed to react in a non-oxidizing atmosphere. The reaction temperature is about 400-1700℃,
Generally, the reaction time is about 0.1 seconds to 5 hours, but it is better to carry out the reaction in two stages rather than in one stage to achieve the purpose of the present invention completely and efficiently. This is preferable because it can be achieved stably. That is, in the first stage, the mixing ratio of each raw material is as described above, and the temperature is 80°C in a non-oxidizing atmosphere.
The entire reaction was carried out at 0 to 1200°C for about 0.1 to 30 seconds, and then as a second stage, the temperature was increased to 130°C in a non-vaporizing atmosphere.
It is appropriate to bake at 0 to 1700°C for about 0.3 to 5 hours. The difference in temperature between the first stage and the second stage is strictly determined by the type of raw materials used, reaction time, etc., but generally the second stage is 300-300°C.
It is desirable that the temperature be as high as about 700°C.

Thus, the object of the present invention is fully achieved,
Furthermore, silicon carbide exhibits sufficiently high thermal conductivity even if it is not a sintered body, and silicon nitride does not necessarily have to be a sintered body, and can exhibit sufficiently high insulation properties.

As the non-oxidizing atmosphere used in the present invention, it is appropriate to employ, for example, a gas flow of argon, nitrogen helium, hydrogen, or the like.

Next, the additive according to the present invention is mixed with a resin, molded into a desired thickness and size, and used as various electronic control boards.

Such resins include, for example, silicone resins.

Resins such as epoxy resin, polyimide, PTFFi, polyvinyl fluoride, and FF1P fluorocarbon can be appropriately employed.

The ratio of these resins and additives is generally 4:1 by volume.
It is appropriate to adopt a ratio of about 1:4 to 1:4, preferably about 4:6 to 3.

If the usage ratio is less than the above range, the intended purpose of the present invention may not be fully achieved; on the other hand, if it exceeds the range, the strength of the substrate may be insufficient. Both are unfavorable since they may cause problems such as cracks.

Unlike the case where silicon carbide is simply coated with an insulating resin, the additive according to the present invention has a semiconductor-like property at the interface between silicon carbide and silicon nitride, which shoulder high electrical resistance. Combined with silicon's inherent high insulating properties, it has the advantage of producing an excellent insulating effect.

Next, the present invention will be explained with reference to examples. Example 1 Using an apparatus consisting of an externally heated flow-through type reaction tube and a reaction product collector, silicon tetrachloride ( Carrier gas: N2) 1 ammonia gas, methylene chloride (carrier gas: N2) in a molar ratio of 1:1.3
: 0.95 and the reaction was carried out by blowing into separate introduction tubes.

Powdered product 'Kl collected in collector (approximately 100°C)
It was transferred to a graphite crucible under an elementary atmosphere and heat-treated at 1550° C. for 2 hours in an argon gas stream.

The analysis results of the obtained powder showed that the SiC content was 94.6 cm,
The Si3N4 content was 4.8%. Moreover, the particle size of this powder was about 0.5μ.

The above powder was mixed with an epoxy resin at a volume fraction of 0.65, and formed into a sheet. Thermal conductivity in the thickness direction of the sheet is 0.13 all/cm -see ℃, specific resistance lO
'. It was more than Ω.

Example 2 Using the same apparatus as in Example 1, dichloroethylene was used instead of methylene chloride, and the molar ratio of the blown gas was changed to silicon tetrachloride: ammonia: dichloroethylene - 1:1.3:
Powder was obtained in the same manner as in Example 1 except that the concentration was 0.49. The obtained powder had a SIC content of 97.1%,
The E113N4 content was 24%. The particle size of this powder was approximately 1.0μ.

The above powder is mixed with silicone resin at a volume fraction of 0.7,
It was formed into a sheet. Thermal conductivity in the thickness direction of the sheet is 0
．． 21 C117cm ・we ・℃, specific resistance 1o10
It was Ω sub or above.

Comparative Example 1 Using only silicon tetrachloride and ammonia gas as blowing gases in the same apparatus as in Example 1, amorphous silicon nitride powder was obtained by reacting at a molar ratio of 12 to 1.3. The silicon nitride powder and carbon black have a molar ratio of silicon to carbon of 1:
After heating in a desired atmosphere at a temperature of 0.95%, the same heat treatment as in Example 1 was performed.

The obtained powder had a SIC content of 943%, a Si3N4 content of 51%, and a particle size of about 0.4μ.

The above powder was mixed with an epoxy resin at a volume fraction of 0.65 and molded into a sheet. Thermal conductivity in the thickness direction of the sheet is 0
．． 15 Cat/cm-(8).degree. C., but the specific resistance was 9, which was a low value of 4.times.10'.OMEGA.

This result is thought to be due to the fact that the SiC powder produced by the reaction between the amorphous silicon nitride powder and carbon black has a structure that does not have a good silicon silicide coating layer.

Claims (1)

[Claims] 1. An electronic material substrate additive consisting of crystal grains made of a composite of silicon carbide and silicon nitride, which have a silicon carbide core and are coated with ff1M silicon oxide. 2. The additive according to claim (1), in which silicon carbide has an average particle size of 0.05 to 10μ. 3. The additive according to claim (1), in which silicon nitride has a thickness of 5 x 10"-' to 1μ. agent.