JP2008160126A - Cooling structure of electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of an electronic component provided with a thermoconductive silicone rubber molding as a thermoconductive material between the thermal electronic component and a thermal dissipation member, which molding has almost no plasticizer added, has a low hardness and a strength, and can be stably manufactured. <P>SOLUTION: The cooling structure is that of an electronic component provided with the thermoconductive material between a thermal boundary surface of the heat generating electronic component and the thermal dissipation member. The thermoconductive material is composed of the thermoconductive silicone molding obtained by curing and molding a composition containing 100 parts by weight of (a) an organopolysiloxane having an alkenyl group in one molecule, 200 to 3,000 parts by weight of (b) a thermoconductive filler, an amount of (c) an organohydrogenpolysiloxane having one or two hydrogen atoms directly bonded to silicon atoms on the average in one molecule, the amount corresponding to 0.1 to 5 equivalents of hydrogen atoms directly bonded to silicon atoms based on the alkenyl group in the (a) component, and 0.1 to 500 ppm of (d) a platinum group curing catalyst to the (a) component in terms of platinum group element. Thereby provided is the cooling structure of an electronic component having as a thermoconductive material the thermoconductive silicone molding having an excellent thermoconductivity, a low hardness and a high strength, and little oil-bleeding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component cooling structure in which a heat transfer material is interposed between a heat boundary surface of a heat-generating electronic component and a heat dissipation member such as a heat sink or a circuit board for cooling the electronic component.

  LSI chips such as CPUs, driver ICs, and memories used in electronic devices such as personal computers, digital video disks, and mobile phones are becoming more and more themselves as performance, speed, size, and integration increase. Heat is generated, and the temperature rise of the chip due to the heat causes malfunction and destruction of the chip. Therefore, many heat dissipating methods for suppressing the temperature rise of the chip during operation and heat dissipating members used therefor have been proposed.

  Conventionally, in an electronic device or the like, a heat sink using a metal plate having a high thermal conductivity such as aluminum or copper is used in order to suppress a temperature rise of a chip during operation. The heat sink conducts heat generated by the chip and releases the heat from the surface due to a temperature difference from the outside air.

  Here, in order to efficiently transfer the heat generated from the chip to the heat sink, it is necessary to closely attach the heat sink to the chip, but because there is a difference in height of each chip and tolerance due to assembly processing, a flexible sheet or The grease is interposed between the chip and the heat sink, and heat conduction from the chip to the heat sink is realized through this sheet or grease.

  Sheets are superior in handling properties compared to grease, and heat conductive sheets (heat conductive silicone rubber sheets) formed of heat conductive silicone rubber or the like are used in various fields.

  These heat conductive sheets are often required to have low hardness in order to improve adhesion to the chip and the heat sink. However, in order to obtain high thermal conductivity, it is necessary to fill the silicone rubber molding with a large amount of heat conductive filler, and the silicone rubber molding with a large amount of filler filled has a very high hardness. It shows a contradictory tendency to end up.

In this case, it is possible to reduce the hardness of the molded product by adding a large amount of plasticizer, but as a result of adding a large amount of plasticizer, a decrease in the hardness of the molded product can be realized, the molded product itself It has been pointed out that there is a problem of oil bleed, which is caused by a decrease in handling property due to a decrease in strength and a plasticizer added after mounting oozes out from a molded product and contaminates the periphery of the mounting part.
In addition, the following are mentioned as prior literature relevant to the present invention.
Registered Utility Model Publication No. 3023821

  The present invention has been made in view of the above circumstances, hardly adds a plasticizer as a heat transfer material between the heat-generating electronic component and the heat dissipation member, has low hardness and strength, and is stable. It is an object of the present invention to provide a cooling structure for an electronic component that includes a thermally conductive silicone rubber molding that can be manufactured.

  As a result of intensive studies to achieve the above object, the present inventor has obtained an organopolysiloxane containing an alkenyl group in one molecule as a composition for obtaining a thermally conductive silicone rubber molded product used as a heat transfer material, Specific amounts of conductive fillers, organohydrogenpolysiloxanes with hydrogen atoms (Si-H groups) directly bonded to silicon atoms, on average 1 to less than 3 per molecule, and platinum group curing catalysts When blended, it was found that almost no plasticizer was added, the hardness was low, the strength was high, and a molded product could be stably obtained, and the present invention was achieved.

Therefore, the present invention
A cooling structure for an electronic component comprising a heat transfer material interposed between a heat boundary surface of the heat-generating electronic component and a heat dissipation member, wherein the heat transfer material is
(A) Organopolysiloxane containing an alkenyl group in one molecule 100 parts by weight (b) Thermally conductive filler 200-3000 parts by weight (c) Silicon atoms having an average of 1 or more and less than 3 in one molecule Organohydrogenpolysiloxane having a hydrogen atom directly bonded to
(A) silicon atom relative to alkenyl group in component
The amount of hydrogen atoms directly bound to 0.1 to 5 equivalents (d) platinum group curing catalyst
(A) 0.1-500 ppm in terms of platinum group element
An electronic component cooling structure comprising a thermally conductive silicone rubber molded product obtained by curing and molding a composition containing the above.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling structure of the electronic component which used the heat conductive silicone molding which has the outstanding heat conductivity, is low hardness, is strong, and has few oil bleeds as a heat transfer material is given.

  The component (a) of the present invention is an organopolysiloxane containing an alkenyl group in one molecule, and preferably contains at least two alkenyl groups in one molecule. Further, it is preferable that the main chain part is basically composed of repeating diorganosiloxane units, and the molecular chain both ends are blocked with a triorganosiloxy group. Organopolysiloxane may contain a branched structure in a part of its molecular structure or may be a cyclic body, but it is linear from the viewpoint of physical properties such as mechanical strength of the cured product. A diorganopolysiloxane in the form of a powder is preferred. The alkenyl group may be present only at both ends of the molecular chain, or may be present at both ends of the molecular chain and in the middle of the molecular chain.

（式中、Ｒ¹は独立に脂肪族不飽和結合を含有しない炭素数１〜１０、好ましくは１〜６の非置換又は置換の１価炭化水素基であり、Ｘはアルケニル基であり、ｎ，ｍは０又は１以上の整数である。） Specific examples of the component (a) include organopolysiloxanes represented by the following general formula (1).

(In the formula, R ¹ independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms not containing an aliphatic unsaturated bond, X represents an alkenyl group, and n , M is 0 or an integer of 1 or more.)

In the formula, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms that does not contain an aliphatic unsaturated bond represented by R ¹ includes, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl Group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and other alkyl groups, cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups, phenyl group, Aryl groups such as tolyl group, xylyl group, naphthyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, methylbenzyl group, etc. A group substituted with a halogen atom such as bromine, cyano group, etc., for example, chloromethyl group, 2-bromoethyl group, 3-chloro Propyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group Preferably, an unsubstituted or substituted methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group, cyanoethyl group, phenyl group, chlorophenyl group, fluorophenyl group, etc. A phenyl group etc. are mentioned.

  Examples of the alkenyl group of X include those having 2 to 8 carbon atoms such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, etc. Among them, vinyl group, allyl group, etc. And a vinyl group is particularly preferable.

  n and m are integers of 0 or 1 or more, preferably an integer satisfying 10 ≦ n + m ≦ 10,000, particularly preferably an integer satisfying 50 ≦ n + m ≦ 2,000, and more preferably 100 ≦ n + m ≦ 1, 000 and an integer satisfying 0 ≦ m / (n + m) ≦ 0.1 are preferable.

  Organopolysiloxanes having a plurality of different viscosities may be used in combination.

  Component (b) includes thermally conductive fillers such as non-magnetic metals such as copper and aluminum, metal oxides such as alumina, silica, magnesia, bengara, beryllia, titania and zirconia, aluminum nitride, silicon nitride and boron nitride. Nitride such as, artificial diamond or silicon carbide is preferable.

  These heat conductive fillers preferably have an average particle size of 0.1 to 100 μm, particularly preferably 0.5 to 50 μm, and more preferably 0.5 to 30 μm. These fillers may be used individually by 1 type, and may mix and use 2 or more types. Two or more kinds of particles having different average particle diameters can be used.

  The blending amount of the component (b) is 200 to 3000 parts by weight, particularly 300 to 1500 parts by weight, with respect to 100 parts by weight of the component (a).

  Component (c) is an organohydrogenpolysiloxane having an average of 1 or more and less than 3 hydrogen atoms directly bonded to silicon atoms in one molecule. The number of hydrogen atoms (that is, Si—H groups) directly bonded to the silicon atom is preferably 1.5 to 2.5 on average per molecule, and more preferably 1.8 to 2.2. When the number of Si—H groups is less than 1, there is a possibility that the composition does not cure. When the number of Si—H groups is 3 or more, it is difficult to obtain a desired softness. However, the number of Si—H groups is not adapted at a single molecule level, and is an average value. A molecule having three or more Si—H groups or a molecule having no Si—H groups is It may exist to some extent.

  Examples of the organohydrogenpolysiloxane include organohydrogenpolysiloxanes represented by the following average composition formulas (2) to (4).

（式中、Ｒ²は独立に脂肪族不飽和結合を含有しない炭素数１〜１０、好ましくは１〜６の非置換又は置換の１価炭化水素基であり、ｏ，ｑ，ｓは０以上の正数、ｐ，ｒ，ｔはそれぞれ、１≦ｐ＜３、ｒ＜２、ｔ＜１を満たす正数である。）

(In the formula, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms not containing an aliphatic unsaturated bond, and o, q and s are 0 or more. Are positive numbers that satisfy 1 ≦ p <3, r <2, and t <1, respectively.)

Examples of the unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms which does not contain an aliphatic unsaturated bond represented by R ² include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert group -Butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and other alkyl groups, cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups, phenyl group, tolyl group, Aryl group such as xylyl group and naphthyl group, aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group and methylbenzyl group, and some or all of hydrogen atoms of these groups may be substituted with fluorine, chlorine, bromine, etc. Groups substituted by halogen atoms, cyano groups, etc., such as chloromethyl, 2-bromoethyl, 3-chloropropyl Pyr group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group , Preferably a methyl group, an ethyl group, a propyl group, a chloromethyl group, a bromoethyl group, a 3,3,3-trifluoropropyl group, a cyanoethyl group, etc. Alternatively, a substituted alkyl group and an unsubstituted or substituted phenyl group such as a phenyl group, a chlorophenyl group, and a fluorophenyl group can be given. The organohydrogenpolysiloxanes represented by the above average composition formulas (2) to (4) may be used alone or in combination of two or more.

  o, q, and s are positive numbers of 0 or more, and p, r, and t are positive numbers that satisfy 1 ≦ p <3, r <2, and t <1, respectively. These numerical values show numerical values in the average composition formula of the component (c), and are not limited for each molecular level.

  Component (c) is added in such an amount that hydrogen atoms directly bonded to silicon atoms are 0.1 to 5 equivalents, preferably 0.3 to 3 equivalents, relative to the alkenyl group in component (a). In an amount of 0.5 to 2 equivalents. When the amount is less than 0.1 equivalent and exceeds 5 equivalent, a desired low-hardness molded product cannot be obtained.

The component (d) platinum group curing catalyst is a catalyst for accelerating the addition reaction of the component (a) alkenyl group and the component (c) Si—H group, and is used as a catalyst for the hydrosilylation reaction. Well-known catalysts are mentioned. Specific examples thereof include platinum group metals such as platinum (including platinum black), rhodium and palladium, H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHPtCl ₆ · nH ₂ O. , KaHPtCl ₆ · nH ₂ O, Na ₂ PtCl ₆ · nH ₂ O, K ₂ PtCl ₄ · nH ₂ O, PtCl ₄ · nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ · nH ₂ O (where, n is an integer of 0-6, preferably 0 or 6), such as platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid (see US Pat. No. 3,220,972) ), A complex of chloroplatinic acid and olefin (see US Pat. Nos. 3,159,601, 3,159,662, and 3,775,452), platinum black, Platinum group metals such as palladium Can be supported on a carrier such as alumina, silica, carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst), platinum chloride, chloroplatinic acid or chloroplatinate and vinyl. A platinum-based catalyst such as a group-containing siloxane is preferable, and a complex with a vinyl group-containing cyclic siloxane is particularly preferable.

  (D) The compounding quantity of a component is 0.1-500 ppm in conversion of a platinum group element with respect to (a) component, Preferably it is 0.5-200 ppm, More preferably, about 1.0-100 ppm is good.

  The composition of the present invention includes a surface treatment agent for a thermally conductive filler, a reaction inhibitor for adjusting the curing rate, a pigment / dye for coloring, and a flame retardancy, as long as the object of the present invention is not impaired. It is possible to add various additives for improving the function, such as an imparting agent, an internal mold release agent for improving mold release from a mold or a separator film.

  The conditions for curing and molding the composition may be the same as those of a known addition reaction curable silicone rubber composition. For example, the composition is cured sufficiently at room temperature, but may be heated as necessary.

  The molded product can be effectively used as a heat conductive sheet for electronic devices and the like. In this case, the hardness of the molded product of the present invention is preferably 5 to 40, particularly 10 to 40 as Asker C hardness.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In addition, the part in a following example shows a weight part, and Me shows a methyl group.

[Example 1]
1000 g of alumina having an average particle diameter of 1 μm and 1000 g of alumina having an average particle diameter of 4 μm were charged into a 500 g dimethylorganopolysiloxane having a viscosity of 600 mm / s sealed with a vinyl group and mixed for 60 minutes. The obtained mixture was further applied to three rolls to obtain a uniform liquid base (I).
To 500 g of liquid base (I), 0.3 g of 2% chloroplatinic acid 2-ethylhexanol solution and 0.2 g of 50% ethynylcyclohexanol toluene solution were added and mixed uniformly.
Furthermore, 15 g of organohydrogenpolysiloxane represented by the following average composition formula (5) was added and mixed uniformly to obtain a composition A.

[Comparative Example 1]
To 500 g of the liquid base (I) obtained in Example 1, 0.3 g of a 2% chloroplatinic acid 2-ethylhexanol solution and 0.2 g of a 50% ethynylcyclohexanol toluene solution were added and mixed uniformly.
Furthermore, 15 g of organohydrogenpolysiloxane represented by the following average composition formula (6) was added and mixed uniformly to obtain a composition B.

[Comparative Example 2]
To 500 g of the liquid base (I) obtained in Example 1, 0.3 g of a 2% chloroplatinic acid 2-ethylhexanol solution and 0.2 g of a 50% ethynylcyclohexanol toluene solution were added and mixed uniformly.
Furthermore, 7.5 g of organohydrogenpolysiloxane represented by the above average composition formula (6) was added and mixed uniformly to obtain a composition C.

[Comparative Example 3]
350 g of dimethylorganopolysiloxane with ends having a viscosity of 600 mm / s sealed with vinyl groups and 150 g of dimethylorganosiloxane with both ends having a viscosity of 300 mm / s blocked with trimethylsilyl groups, 1000 g of alumina with an average particle size of 1 μm and an average particle size of 4 μm 1000 g of alumina was charged into a Shinagawa universal agitator and mixed for 60 minutes. The obtained mixture was further applied to three rolls to obtain a uniform liquid base (II).
To 500 g of liquid base (II), 0.3 g of a 2% chloroplatinic acid 2-ethylhexanol solution and 0.2 g of a 50% ethynylcyclohexanol toluene solution were added and mixed uniformly.
Furthermore, 5 g of organohydrogenpolysiloxane represented by the above average composition formula (6) was added and mixed uniformly to obtain a composition D.

  Each of the compositions A to D obtained in Examples and Comparative Examples was heat-cured to a thickness of 2.0 mm under the conditions of 120 ° C. × 10 minutes, and using the obtained sheet, the tensile strength was determined according to JIS K 6249. The elongation at break and the tear strength were measured. Moreover, the thermal resistance was measured by the following method. The results are shown in Table 1.

Measurement of thermal resistance A sample sheet is placed between a model heater (installation area 7 cm ² ) in which a heater is embedded in a transistor TO-3 type aluminum case and a heat sink (flat type 60F 230 × 70 mm: made by LEX). Crimping was performed with a load of 300 gf / cm ² , and 28 W of power was applied to the model heater. The temperature T1 (° C.) of the model heater and the temperature T2 (° C.) of the heat sink were measured with a thermocouple, and the thermal resistance of the sample was obtained from the following equation.
R (° C./W)=(T1-T2)/28

  Compositions A to D obtained in Examples and Comparative Examples were heat-cured to a thickness of 6 mm under curing conditions of 120 ° C. × 10 minutes, the hardness of the cured product was measured by the following method, and the presence or absence of oil bleed was confirmed. . The results are shown in Table 1.

Measurement of Hardness The hardness was measured by applying 2 kg of 6 mm thick molded articles and using a polymer meter Asuka-C type hardness tester under a load of 1 kg.
Confirmation of presence or absence of oil bleed The molded product after the hardness measurement was placed on a filter paper and left in an atmosphere of 120 ° C. for 24 hours, and the presence or absence of oil transfer onto the filter paper was visually confirmed.

Claims (5)

A cooling structure for an electronic component comprising a heat transfer material interposed between a heat boundary surface of the heat-generating electronic component and a heat dissipation member, wherein the heat transfer material is
(A) Organopolysiloxane containing an alkenyl group in one molecule 100 parts by weight (b) Thermally conductive filler 200-3000 parts by weight (c) Silicon atoms having an average of 1 or more and less than 3 in one molecule Organohydrogenpolysiloxane having a hydrogen atom directly bonded to
(A) silicon atom relative to alkenyl group in component
The amount of hydrogen atoms directly bound to 0.1 to 5 equivalents (d) platinum group curing catalyst
(A) 0.1-500 ppm in terms of platinum group element
A cooling structure for an electronic component, comprising a thermally conductive silicone rubber molded product obtained by curing and molding a composition containing the above.   The heat conductive filler as component (b) is one or more heat conductive fillers selected from the group consisting of metals, metal oxides, nitrides, artificial diamond and silicon carbide. The cooling structure according to claim 1.   The cooling structure according to claim 2, wherein the metal is copper and / or aluminum.   The cooling structure according to claim 2, wherein the metal oxide is one or more selected from the group consisting of alumina, silica, magnesia, bengara, beryllia, titania, and zirconia.   The cooling structure according to claim 2, wherein the nitride is one or more selected from the group consisting of aluminum nitride, silicon nitride, and boron nitride.