JP2003133769A - Heat dissipating sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat dissipating sheet with improved peeling property, with no degraded heat dissipating property. SOLUTION: A heat dissipating sheet 10 comprises a base material 11 of silicone resin in which a heat-conductive filer is dispersed, with a surface layer 12 coated on the surface of base material 11. Related to the surface layer 12, beads 13, including either or both of glass beads and silicone resin beads, are dispersed in a silicone resin 14. The beads 13 make the surface of surface layer 12 rough, resulting in degraded or eliminated adhesion on the surface of surface layer 12. As a result, blocking caused by adhesion is prevented when the heat dissipating sheet 10 is laminated, allowing peeling sheet by sheet with no breakage. Even if a heatsink is removed while the heat dissipating sheet is interposed between a heating component and the heatsink, it is easily removed thanks to low adhesion or no adhesion on the surface of heat dissipating sheet 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiation sheet arranged on the surface of a heat generating component such as a CPU.

[0002]

2. Description of the Related Art Conventionally, heat-generating components, such as CPUs, which generate heat when used, are often deteriorated in performance or damaged by heat. In such a heat-generating component, it is widely practiced to fix a heat radiator including a cooling fin or a cooling fan on the surface of the heat-generating component to cool the heat-generating component. At that time, a heat radiating sheet is provided between the heat generating component and the radiator for the purpose of protecting the heat generating component and preventing a gap between the surface of the heat generating component and the radiator.

Since the heat radiation sheet is interposed between the heat-generating component and the heat radiator, if the heat-generating component or the heat radiator has poor adhesion or a large thickness, the cooling effect of the heat radiator may be hindered. become. For this reason, it is preferable that the heat radiation sheet has low hardness and thinness, but the heat radiation sheet is packaged in a laminated state at the time of storage or transportation before being mounted on the heat-generating component. Even if they are laminated with each other, the heat-dissipating sheet sticks and is difficult to peel off, and is easily broken.

Therefore, a metal woven cloth, non-woven cloth,
Those provided with a reinforcing layer composed of a film, a cured resin layer or the like (JP-A-6-155517, JP-A-2-19)
No. 6453) and a powder using a so-called blocking (adhesion) inhibitor as a dusting powder have been proposed.

However, the conventionally proposed reinforcing layer such as a metal woven cloth has a problem that the heat dissipation sheet is inevitably increased because the thickness of the heat dissipation sheet becomes large, and the use of the anti-blocking agent requires the use of the heat dissipation sheet. The anti-blocking agent may become dust during mounting, which may adversely affect electronic components.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a heat dissipation sheet having improved peelability without impairing heat dissipation.

[0007]

According to a first aspect of the present invention, there is provided a heat dissipation sheet in which a base material made of a silicone resin in which a heat conductive filler is dispersed and a surface layer is formed by coating on the surface of the base material. One or both of the glass beads and the silicone resin beads are dispersed in a silicone resin.

The invention of claim 2 is characterized in that, in claim 1, the beads in the surface layer have an average particle diameter of 10 to 100 μm.

[0009]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of a heat dissipation sheet according to an embodiment of the present invention.
The heat dissipation sheet 10 according to the present invention is used by being sandwiched between a heat generating component such as a CPU and a heat radiator, and is applied to the base material 11 and one side (this embodiment) or both side surfaces of the base material 11. It is composed of the formed surface layer 12.

The base material 11 constitutes the main body of the heat dissipation sheet 10, retains the shape of the heat dissipation sheet 10, and forms the surface layer 12.
Support. Various materials can be used as the base material 11, but a material in which a heat radiation filler is mixed with a silicone resin is preferable in terms of flexibility and easy handling. More specifically, liquid silicone resin or gel silicone resin, boron nitride as a heat dissipation filler, silicon nitride,
The base material 11 is formed by kneading a heat conductive filler such as aluminum nitride or alumina, kneading the mixture into a sheet by extrusion molding, calender molding or the like and curing it. As an example of the liquid silicone resin, a highly thermal conductive silicone resin manufactured by Shin-Etsu Chemical Co., Ltd., trade name: X32
-2020 and X-32-2152 can be mentioned. Further, as an example of the gel silicone resin, GE
A heat dissipation silicone gel manufactured by Toshiba Silicone Co., Ltd., trade name: TSE3081 can be mentioned.

The ratio of the heat-releasing filler to the silicone resin is set appropriately, but as an example, silicone resin 1
The case of 50 to 500 parts by weight with respect to 00 parts by weight will be described. Further, the thickness of the base material 11 is appropriately set, but an example of about 0.5 to 3 mm is shown.

The surface layer 12 is composed of glass beads, silicone resin beads, or both beads 13 dispersed in a silicone resin 14.
It is formed by coating on the surface of 1. The surface layer 12 is not limited to being provided on only one side surface of the base material 11 as in the illustrated example, and may be provided on both side surfaces of the base material 11. If the surface layer 12 is provided only on one side of the base material 11, the other surface of the base material 11 on which the surface layer 12 does not exist is replaced by the CPU.
It can be closely attached to heat-generating components such as
There is no risk of damaging expensive heat-generating components due to the beads 13 dispersed in.

As the glass beads, not only general-purpose glass beads but also recycled glass beads obtained by crushing and polishing waste glass can be used. The general-purpose glass beads are obtained by melting glass at a high temperature, causing it to flow in a gas phase, successively dropping and cooling. The silicone resin beads are preferably resin beads made of methacrylic resin coated with silicone resin. The beads 13 made of one or both of the glass beads and the silicone resin beads have an average particle diameter of 10 to 100.
μm, preferably 15 to 50 μm, more preferably 18
˜30 μm. Within this range, the unevenness of the surface of the surface layer 12 becomes appropriate, and the surface layer 12 can be made to have reduced adhesiveness or non-adhesiveness, and the surface of the mating surface, such as a heat-generating component or a radiator, can be formed. It is possible to prevent the gap between them from becoming large and maintain good thermal conductivity of the heat dissipation sheet 10. When both glass beads and silicone resin beads are used, the ratio of both beads is appropriately determined.

The silicone resin 14 in which the beads 13 are dispersed fixes the beads 13 to the surface of the base material 11 and prevents the surface of the heat dissipation sheet 10 from becoming significantly uneven due to the protrusion of the beads 13. The silicone resin 1
As 4, a cured product of an addition polymerization type liquid silicone rubber is preferable. This addition polymerization type liquid silicone rubber is a one-component silicone having both a vinyl group and an H-Si group in one molecule, or an organopolysiloxane having a vinyl group at the terminal or side chain and 2 at the terminal or side chain.
A two-component silicone composed of an organopolysiloxane having one or more H-Si groups can be used. As an example of such an addition polymerization type liquid silicone rubber, Toray Dow Corning Silicone Co., Ltd.
Trade name: CY52-238A / B can be mentioned.

The amount of the beads 13 and the silicone resin 14 constituting the surface layer 12 is preferably 5 to 300 parts by weight with respect to 100 parts by weight of the silicone resin 14. When the amount is less than 5 parts by weight, the surface of the surface layer 12 does not have irregularities and non-adhesiveness cannot be obtained. Also, 300
When it exceeds the weight part, the viscosity of the coating liquid composed of the beads 13 and the silicone resin 14 becomes too high, which makes it difficult to apply the coating liquid to the surface of the base material 11, and the surface layer 12
The non-adhesiveness of the surface hardly changes even when the number of beads 13 increases, so that the addition of beads 13 becomes useless. The thickness of the surface layer 12 is 5 to 30 μm, preferably 8 to 16 μm. The thickness of this range is set so that the beads 13 can be microscopically adhered in the thickness direction of the surface layer 12 by one bead particle, so that the surface of the surface layer 12 is appropriately reduced in adhesiveness or non-adhesiveness, and heat dissipation is achieved. It is preferable in that the thickness of the sheet 10 is prevented from being excessively increased.

As described above, the surface layer 12 has the beads 13
A coating liquid consisting of a silicone resin 14 and a silicone resin 14 is applied to the surface of the base material 11 and cured by heating. The base material 11 is also made of a silicone resin. The silicone resin 14 for the surface layer is partially impregnated in the silicone resin of the material 11, and the boundary 12 a between the base material 11 and the surface layer 12 is not formed. Thereby, the surface layer 12 and the base material 11 are firmly integrated, and the surface layer 12 can be prevented from peeling from the base material 11. The coating liquid may be applied to the surface of the substrate 11 by sheeting using a known applicator, a roll coater, a gravure coater, or the like.

In the surface layer 12, a heat conductive filler such as boron nitride, silicon nitride, aluminum nitride or alumina is dispersed as a heat radiation filler, and the surface layer 1 is dispersed.
It is also possible to improve the heat conductivity of No. 2 and improve the heat dissipation. In that case, the average particle diameter of the heat radiation filler is 10 to 6
It is 0 μm, preferably 20 to 40 μm.

The heat radiating sheet 10 thus formed is stored or transported in a laminated and packed state,
When mounted on a heat-generating component such as U, they are peeled one by one from the laminated state. At that time, the surface of the surface layer 12 has beads 13
Since the heat dissipation sheets 10 are uneven and have reduced adhesiveness or non-adhesiveness, it is possible to prevent the heat dissipation sheets 10 from adhering to each other and to be blocked, and the heat dissipation sheets 10 can be peeled off without tearing. The heat radiation sheet 10 peeled off one by one
Is sandwiched between the heat-generating component and the radiator, and is pressed between the radiator and the heat-generating component by a clip or the like. At that time, the beads 13 exposed on the surface of the surface layer 12 and partially protruding are
The surface layer 1 is buried in the surface layer 12 or the base material 11 due to the pressure between the radiator and the heat-generating component.
The heat dissipating sheet 10 exhibits good heat conductivity and heat dissipating property without impairing the adhesiveness between the surface of 2 and the heat dissipating component.

[0019]

EXAMPLES Specific examples will be described below. First, uncured gel silicone resin (trade name: TSE3
070, 100 parts by weight of GE Toshiba Silicone Co., Ltd. and alumina powder (average particle size 37 μm, trade name: AS-1)
0, a mixture with 300 parts by weight of Showa Denko KK was supplied between the fluororesin films and pressed with a pressure roll to give 180
It heated at -220 degreeC and formed the sheet-shaped base material which consists of thickness 2mm.

Liquid silicone rubber (trade name: TS
E3033, 100 parts by weight of GE Toshiba Silicone Co., Ltd., and glass beads (average particle diameter 18 μm, trade name: GB
731M, manufactured by Toshiba Ballotini Co., Ltd., 50 parts by weight,
Aluminum oxide (average particle size 21 μm, trade name: AS-20,
50 parts by weight of Showa Denko KK were mixed and stirred with a planetary mixer, and then degassed in vacuum to prepare a coating liquid. This coating liquid was put into a hopper of a roll coater and applied on the surface of the sheet-shaped base material so as to have a thickness of 10 μm. Then, the coated product was housed in a hot air drying oven and heated at a temperature of 180 ° C. for 30 minutes to be cured, and a surface layer in which glass beads were dispersed in a silicone resin was provided on the surface of the substrate. After that, it was cut into a plan view of 250 × 250 mm to obtain 10 heat dissipation sheets of the example.

The heat-dissipating sheets of the above-mentioned embodiment were laminated and
After leaving it for a day, it was peeled off one by one, and there was no blocking between the heat dissipation sheets, and it could be peeled off satisfactorily without tearing. Further, when the heat dissipation sheet of this embodiment was attached between the CPU and the radiator in a home computer capable of measuring and displaying the temperature of the CPU and the temperature of the CPU when the computer was operating was confirmed, the temperature of the CPU was in the normal range. It was confirmed that the heat dissipation sheet exhibited good thermal conductivity. Further, the work of mounting the heat radiation sheet between the CPU and the heat radiator was easy.

[0022]

As shown and described above, according to the present invention, glass beads, silicone resin beads, or both beads are provided on the surface of a substrate made of a silicone resin having a thermally conductive filler dispersed therein. Since the surface layer dispersed in the silicone resin was formed by coating, the surface layer becomes a non-tacky one with a reduced adhesiveness due to the beads. Therefore, when a plurality of heat dissipation sheets according to the present invention are stacked and peeled off, the heat dissipation sheet is not blocked and the heat dissipation sheet can be favorably removed without tearing. Also, when the radiator is attached to a heat-generating component such as a CPU via the heat-dissipating sheet of the present invention and the radiator is removed for replacement of the heat-generating component, the surface layer of the heat-dissipating sheet is made of beads. Since the presence of the adhesive reduces the adhesiveness or makes it non-adhesive, the radiator can be easily removed from the heat-generating component.

Further, in the heat dissipation sheet of the present invention, since the base material and the surface layer formed by coating on the surface of the base material are both composed of silicone resin, they are firmly integrated,
There is no risk of the surface layer peeling from the substrate. Further, since the base material and the surface layer are made of a silicone resin, they have flexibility, and when the heat radiating sheet is pressed between the heat-generating component and the radiator, the beads protruding from the surface layer may be in the surface layer or the base layer. Since it is pushed into the material, it does not impair the adhesion between the heat dissipation sheet and the heat-generating components and the heat radiator, and exhibits good heat conductivity and heat dissipation.

Furthermore, when the beads in the surface layer have an average particle size of 10 to 100 μm as in claim 2, it is possible to more effectively realize the tackiness reduction or the non-tackiness imparting to the surface layer.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a heat dissipation sheet according to an embodiment of the present invention.

[Explanation of symbols]

10 Heat dissipation sheet 11 Base material 12 surface 13 beads 14 Silicone resin on the surface

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Claims (2)

[Claims] 1. A heat dissipation sheet having a base material made of a silicone resin having a thermally conductive filler dispersed therein and a surface layer formed by coating on the surface of the base material, wherein the surface layer is either glass beads or silicone resin beads, or A heat dissipation sheet, characterized in that both beads are dispersed in silicone resin. 2. The beads in the surface layer have an average particle size of 10 to 100.
The heat dissipation sheet according to claim 1, wherein the heat dissipation sheet has a thickness of μm.