JP2012214612A - Silicone heat dissipation member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone heat dissipation member maintaining thermal conductivity characteristics for a long time under high-humidity/temperature, having low elasticity, an excellent tracking property to substrate and adhesion.SOLUTION: The silicone heat dissipation member is obtained by hardening a silicone resin composition comprising (a) an organopolysiloxane having at least two C-C double bonds reacting with SiH group in a molecule, (b) an organohydrogenpolysiloxane having at least two SiH groups in a molecule, (c) an addition reaction catalyst, (d1) alumina with an average particle size of 1-10 μm, (d2) alumina with an average particle size of 10-25 μm, and (d3) alumina with an average particle size of 30-70 μm.

Description

  The present invention relates to a silicone heat dissipating member that can maintain heat conduction characteristics for a long time even under high temperature and high humidity, and has low elasticity and excellent followability and adhesion to a substrate.

  As a heat dissipation material for an electronic member, a material obtained by curing and molding a silicone resin mixed with various inorganic fillers is used. In order to improve the heat dissipation characteristics, studies have been made so far on the types and particle diameters of inorganic fillers and combinations thereof, but the heat dissipation characteristics are still insufficient. In addition, when trying to improve the thermal conductivity of the heat radiating member, the blending ratio of the inorganic filler increases, but the cured product becomes hard, so the followability to the base material and the adhesiveness are lowered, and the heat radiating characteristics are lowered. There was a problem.

Patent Document 1 discloses a silicone heat dissipating member using two or more inorganic fillers having different average particle diameters, but there is room for improvement in heat dissipating characteristics.
JP 2002-3831 A

  An object of the present invention is to provide a silicone heat radiating member that can maintain heat conduction characteristics for a long time even under high temperature and high humidity, and has low elasticity and excellent followability and adhesion to a substrate.

  The present invention relates to an organopolysiloxane (a) containing at least two carbon-carbon double bonds reactive with SiH groups in one molecule, and an organohydrogen containing at least two SiH groups in one molecule. Polysiloxane (b), addition reaction catalyst (c), alumina (d1) having an average particle diameter of 1 μm or more and less than 10 μm, alumina (d2) having an average particle diameter of 10 μm or more and less than 25 μm, average particle diameter It is obtained by hardening the silicone resin composition containing the alumina (d3) whose is 30-70 micrometers. It is a silicone heat radiating member characterized by the above-mentioned.

  The silicone heat dissipating member of the present invention has excellent heat dissipating properties, can maintain heat conducting properties for a long time even under high temperature and high humidity, and is suitable as a heat dissipating material for electronic members because of its low elasticity and excellent followability and adhesion to the substrate. .

  The silicone heat dissipating member of the present invention contains an addition type silicone resin as a resin component. Organopolysiloxane (a) containing at least two carbon-carbon double bonds having reactivity with SiH group in one molecule is vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group, An organopolysiloxane containing at least two carbon-carbon double bonds such as a hexenyl group in one molecule. Examples of the organopolysiloxane include those in which the main chain is a repeating unit of diorganosiloxane and the terminal has a triorganosiloxane structure, and may have a branched or cyclic structure. Examples of the organo structure bonded to silicon in the terminal or repeating unit include a methyl group, an ethyl group, and a phenyl group. Specific examples include dimethylpolysiloxane having vinyl groups at both ends.

  The organohydrogenpolysiloxane (b) containing at least two SiH groups in one molecule is an organopolysiloxane containing two or more SiH groups in the terminal and / or repeating structure. Examples of the organopolysiloxane include those in which the main chain is a repeating unit of diorganosiloxane and the terminal has a triorganosiloxane structure, and may have a branched or cyclic structure. Examples of the organo structure bonded to the terminal or the silicon in the repeating unit include a methyl group, an ethyl group, a phenyl group, and an octyl group, and it can be said that two or more of these are substituted with a hydrogen group. The blending ratio of the organopolysiloxane (a) and the organohydrogenpolysiloxane (b) is preferably (a) :( b) = 1: 1.0 to 2.0, more preferably (a). : (B) = 1: 1.3 to 1.6.

  The addition reaction catalyst (c) is added to promote the hydrosilylation reaction of the component (a) and the component (b), and a known metal, metal compound, metal complex or the like having catalytic activity for the hydrosilylation reaction is added. Can be used. In particular, it is preferable to use platinum, a platinum compound, or a complex thereof. These catalysts may be used alone or in combination of two or more. A cocatalyst may be used in combination. The addition amount of the addition reaction catalyst (c) is preferably 1 ppm to 50 ppm, more preferably 2 to 10 ppm with respect to the entire composition.

The silicone heat dissipating member of the present invention contains three types of alumina having different particle diameters as the thermally conductive inorganic filler. Specifically, alumina (d1) having an average particle diameter of 1 μm or more and less than 10 μm, alumina (d2) having an average particle diameter of 10 μm or more and less than 25 μm, alumina having an average particle diameter of 30 to 70 μm (d3) ). When the total of (d1), (d2), and (d3) is 100 parts by weight, (d1) is 10 to 30 parts by weight, (d2) is 5 to 20 parts by weight, and (d3) is 50 to 85 parts by weight. It is preferable to blend so that. Moreover, it is preferable to mix | blend so that the sum total of (d1), (d2), (d3) may be 85 to 95 weight% of the whole silicone resin composition.
By blending three types of alumina having different particle sizes, it is surmised that the increase in the filling rate of the thermally conductive inorganic filler contributes to the improvement of the heat dissipation characteristics. On the other hand, even if the filling rate is too high, the cured product becomes hard, and the followability to the substrate and the adhesion are deteriorated.

In addition to the above essential components, various resins and additives can be blended in the curable silicone resin composition of the present invention. Viscosity, flexibility, etc. can be adjusted by blending the diluent. Specific examples include phthalate-based diluents such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, silicone oils such as dimethyl silicone oil, alkyl-modified silicone oil, and polyether-modified silicone oil. , Dioctyl adipate, diisononyl adipate, dialkyl azelate, dibutyl sebacate, epoxidized soybean oil, polypropylene glycol, acrylic polymer, α-olefin and derivatives thereof, and 2-ethylhexyl ester compounds of vegetable oil-derived fatty acids.

  For the purpose of adjusting viscosity, adjusting viscosity, increasing weight, etc., fillers such as calcium carbonate, cinnabar, talc, carbon black, titanium oxide, kaolin, silicon dioxide, melamine, reinforcing materials such as glass fiber for reinforcing cured resin, Hollow bodies such as shirasu balloons and glass balloons can be added for weight reduction and viscosity adjustment. In addition, antioxidants, pigments, preservatives, and the like can be used as appropriate.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and demonstrated in detail about this invention, a specific example is shown and it does not specifically limit to these.

Example 1
An average particle diameter of 40 parts by weight of polymethylvinylsiloxane having a viscosity of 3.5 Pa · s and 60 parts by weight of organohydrogenpolysiloxane having a viscosity of 3.2 Pa · s containing SiH groups as a thermally conductive inorganic filler. 160 parts by weight of alumina (made by Showa Denko KK, trade name CB-P05) which is 4 μm, 60 parts by weight of alumina (made by Showa Denko KK, trade name CB-A20S) whose average particle diameter is 20 μm, and the average particle diameter is 520 parts by weight of alumina (trade name CB-A50S, manufactured by Showa Denko KK), which is 50 μm, was mixed to make the filler filling rate 88%. Furthermore, 0.015 parts by weight of 1-ethynyl-1-cyclohexanol (ECH) and 1 part by weight of carbon black (trade name: Asahi Thermal Co., Ltd., manufactured by Asahi Carbon Co., Ltd.) are added as a colorant for the purpose of retarding curing. The silicone resin composition of Example 1 was produced by adding and mixing a platinum-vinylsiloxane complex as a reaction catalyst so as to be 10 ppm with respect to the entire composition.

Comparative Example 1
In Example 1, 40 parts by weight of alumina having a mean particle size of 12 μm (product name: V325F, manufactured by Nippon Light Metal Co., Ltd.) and alumina having a mean particle size of 20 μm (made by Showa Denko KK Example 1 except that 120 parts by weight of CB-A20S) and 400 parts by weight of alumina (trade name CB-A50S, manufactured by Showa Denko KK) with an average particle size of 50 μm were used and the filler filling rate was 85%. In the same manner, a silicone resin composition of Comparative Example 1 was produced.

Comparative Example 2
In Example 1, 160 parts by weight of alumina (made by Showa Denko KK, trade name CB-P05) having an average particle diameter of 4 μm as a thermally conductive inorganic filler, alumina (made by Showa Denko KK) having an average particle diameter of 50 μm , Trade name CB-A50S) A silicone resin composition of Comparative Example 2 was prepared in the same manner as in Example 1 except that 400 parts by weight was used and the filler filling rate was 85%.

Comparative Example 3
In Example 1, 370 parts by weight of alumina (manufactured by Showa Denko KK, trade name CB-P05) having an average particle diameter of 4 μm as the thermally conductive inorganic filler, alumina (manufactured by Showa Denko KK) having an average particle diameter of 20 μm , Trade name CB-A20S) A silicone resin composition of Comparative Example 3 was produced in the same manner as in Example 1 except that 190 parts by weight and a filler filling rate of 85% were used.

Measurement method of thermal conductivity Each curable silicone resin composition was molded into 60 x 120 mm, and heat was measured using a rapid thermal conductivity meter (trade name QTM-500, manufactured by Kyoto Electronics Industry Co., Ltd.) in an atmosphere at 23 ° C. Conductivity was measured.

  The silicone heat radiating member of the example was superior in thermal conductivity to the silicone heat radiating member of the comparative example.

Claims (3)

  Organopolysiloxane containing at least two carbon-carbon double bonds having reactivity with SiH groups in one molecule (a) Organohydrogenpolysiloxane containing at least two SiH groups in one molecule (b) ), Addition reaction catalyst (c), alumina (d1) having an average particle size of 1 μm or more and less than 10 μm, alumina (d2) having an average particle size of 10 μm or more and less than 25 μm, and an average particle size of 30 to 70 μm A silicone heat dissipating member obtained by curing a silicone resin composition containing alumina (d3).   Sum of alumina (d1) having an average particle diameter of 1 μm or more and less than 10 μm, alumina (d2) having an average particle diameter of 10 μm or more and less than 25 μm, and alumina (d3) having an average particle diameter of 30 to 70 μm 2. The silicone according to claim 1, wherein (d1) is from 10 to 30 parts by weight, (d2) is from 5 to 20 parts by weight, and (d3) is from 50 to 85 parts by weight, assuming that 100 parts by weight. Heat dissipation member. The total of (d1), (d2), and (d3) is 85 to 95% by weight of the entire silicone resin composition.