Heat-conductive sheet

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a thermally conductive sheet. More specifically, the present invention relates to a heat conductive sheet used as a heat radiating material for efficiently dissipating heat generated from heat generating parts of various electric and electronic devices.

【0002】

[Conventional technology]

In various electric and electronic devices, it is important to efficiently dissipate heat generated from heat-generating parts in order to prevent malfunction and extend product life. Therefore, conventionally, in electric and electronic devices having parts that generate heat, a heat radiating material for dissipating the generated heat has been used.

【0003】

As one of the above heat-dissipating materials, a heat conductive sheet in which silicone rubber is coated on at least one surface of a graphite sheet is disclosed in Tokusho 3-51302. This heat conductive sheet is easy to handle due to its shape, and has silicone rubber on at least one side, and has good adhesion to the mounting target part, which is convenient as a heat radiating material for electrical and electronic equipment. It is supposed to be. However, since this heat conductive sheet is made only by applying silicone rubber to the graphite sheet, the adhesion between the graphite sheet and the silicone rubber becomes insufficient and peeling occurs, or bubbles or voids are generated on the adhesion surface. was there. Moreover, its heat dissipation performance was not sufficiently high, and there was room for improvement. Further, as a result of deforming the heat conductive sheet along the attachment target portion, the graphite sheet is cleaved, and in some cases, the graphite is missing as a cleaved piece, and there is a problem in terms of reliability during use. Further, even at the time of manufacturing the graphite sheet, it is difficult to apply sufficient winding tension because the graphite sheet may be torn when it is manufactured as a continuous sheet, which leaves a problem in mass productivity.

【0004】

Therefore, the present inventor has developed a new heat conductive sheet that solves the above problems, and has already applied for a patent (Japanese Patent Application No. 2000-340460, Japanese Patent Application No. 2000-341026, and Japanese Patent Application No. 2000-341029). ). In these inventions, a sheet-like graphite layer and a sheet-like elastomer layer are laminated, and a heat-conductive filler such as soft magnetic ferrite is blended in the sheet-like elastomer layer to improve the overall heat conductivity (heat dissipation). It has been greatly improved. Further, the graphite layer and the elastomer layer are formed by pressurizing the sheet-like elastomer layer at a specific pressure when laminating the sheet-like elastomer layer, or by forming holes in the sheet-like graphite layer and inserting a part of the sheet-like elastomer layer into the holes. And are strongly adhered to each other to prevent peeling between layers. Further, by embedding the woven cloth or the non-woven fabric in the elastomer layer by attaching it to the sheet-shaped graphite layer or the like, the sheet-shaped graphite layer is reinforced and the graphite is prevented from being torn or cleaved to be reliable. The sex is greatly improved.

【0005】

However, when the woven fabric or the non-woven fabric is embedded as described above, the thermal conductivity is lowered due to the presence of the woven fabric or the non-woven fabric, so that there is a limit to the improvement of the overall thermal conductivity. Therefore, the advantage of blending the heat conductive filler was not fully utilized, and there was room for improvement.

【0006】

[Problems to be Solved by the Invention]

Therefore, in view of the above-mentioned conventional situation, the present invention has high thermal conductivity while maintaining the advantages of the woven fabric or the non-woven fabric, that is, the advantages of preventing defects such as cleavage due to deformation and being excellent in mass productivity. Another object of the present invention is to provide a novel thermally conductive sheet in which the graphite layer and the elastomer layer are strongly adhered to each other and do not cause peeling or the like.

【0007】

[Means for solving problems]

In order to solve the above problems, in the heat conductive sheet of the present invention, as claim 1, a woven fabric or a non-woven fabric is attached to one surface of the sheet-like graphite layer with an adhesive containing a heat conductive additive. A sheet-like elastomer layer is laminated on both the woven fabric or the non-woven fabric and the other surface of the sheet-like graphite layer, and a heat conductive filler is blended in at least one of the both sheet-like elastomer layers. It is characterized by being.

【0008】

Further, in claim 2, a woven fabric or a non-woven fabric is attached to one surface of the sheet-shaped graphite layer with an adhesive containing a thermally conductive additive, and a sheet is attached to the other surface of the sheet-shaped graphite layer. The sheet-like elastomer layer is laminated, and the sheet-like elastomer layer is blended with a heat conductive filler.

【0009】

Further, in claim 3, a woven fabric or a non-woven fabric is attached to one surface of the sheet-shaped graphite layer with an adhesive containing a heat conductive additive, and the sheet-shaped elastomer layer is laminated on the woven fabric or the non-woven fabric. The sheet-like elastomer layer is blended with a heat conductive filler.

【0010】

Further, in claim 4, a woven fabric or a non-woven fabric is attached to both sides of the sheet-shaped graphite layer with an adhesive containing a heat conductive additive, and is attached to both the woven fabric or the non-woven fabric attached to both sides. The sheet-like elastomer layer is laminated, and at least one of both of the sheet-like elastomer layers is blended with a heat conductive filler.

【0011】

Further, in claim 5, a woven fabric or a non-woven fabric is attached to both sides of the sheet-shaped graphite layer with an adhesive containing a heat conductive additive, and is attached to one of the woven fabric or the non-woven fabric attached to both sides. The sheet-like elastomer layer is laminated, and the sheet-like elastomer layer is blended with a heat conductive filler.

【0012】

According to the configurations of claims 1 to 5, the sheet-like graphite layer is reinforced by the woven fabric or the non-woven fabric, the sheet-like graphite layer flexibly follows the overall deformation, and the graphite is not cleaved. In addition, the additive in the adhesive compensates for the decrease in thermal conductivity due to the presence of the woven fabric or non-woven fabric, and the overall thermal conductivity is maintained high.

【0013】

A sixth aspect of the present invention is the heat conductive sheet according to any one of the first to fifth aspects, wherein the sheet-like graphite layer is communicated with the woven fabric or the non-woven fabric, and holes are formed in the thickness direction. It is characterized in that the protrusion of the elastomer protruding from the sheet-like elastomer layer is fitted therein.

【0014】

According to claim 7, in the heat conductive sheet according to claim 1 or 4, holes are formed in the thickness direction through the sheet-shaped graphite layer and the woven fabric or non-woven fabric, and the holes are formed into a sheet-like shape. It is characterized in that an elastomer protrusion protruding from the elastomer layer is fitted, and both sheet-like elastomer layers are integrally bonded via the protrusion.

【0015】

Further, claim 8 is characterized in that, in the heat conductive sheet according to claim 6 or 7, the woven fabric or the non-woven fabric has entered along the holes formed in the sheet-shaped graphite layer.

【0016】

According to the configurations of claims 6 to 8, the woven fabric, the non-woven fabric, or the sheet-like elastomer layer enters the holes formed in the sheet-like graphite layer, and the adhesion between the layers becomes stronger to prevent peeling and the like. Will be done.

【0017】

Further, claim 9 is characterized in that, in the heat conductive sheet according to any one of claims 1 to 8, the additive contained in the adhesive is one or more selected from carbon powder, aluminum nitride, and boron nitride. And.

【0018】

According to the above configuration, a specific type of additive contained in the adhesive is specified in consideration of thermal conductivity, electrical insulation, dispersibility in the adhesive, and the like.

【0019】

Further, claim 10 states that in the heat conductive sheet according to any one of claims 1 to 9, the heat conductive filler is one or more selected from soft magnetic ferrite, aluminum nitride, silicon nitride, and alumina. It is a feature.

【0020】

According to the above configuration, a specific type of the heat conductive filler is specified in consideration of heat conductivity, dispersibility in the sheet-like elastomer layer, and the like.

【0021】

Further, claim 11 is characterized in that, in the heat conductive sheet according to any one of claims 1 to 10, the sheet-like elastomer layer is composed of silicone rubber.

【0022】

According to the above configuration, silicone rubber is particularly selected among various elastomeric substances. Silicone rubber is most suitable as a heat conductive sheet because it flexibly adheres to a mounting target portion such as an electronic component and a sheet-like graphite layer and has heat resistance.

【0023】

Further, claim 12 is the heat conductive sheet according to any one of claims 1 to 11, wherein the basis weight of the woven fabric or the non-woven fabric is 10 to 30 g / m.²It is characterized by being.

【0024】

According to the above configuration, the range of the basis weight of the woven fabric or the non-woven fabric is optimized from the viewpoint of sufficiently exerting the reinforcing effect without lowering the thermal conductivity.

【0025】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 shows an embodiment (1) of the present invention. In the heat conductive sheet 1 of FIG. 1, first, a woven fabric or a non-woven fabric 11 is attached to one surface of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. Then, the sheet-like elastomer layers 14 and 14'are laminated on both the woven fabric or the non-woven fabric 11 and the other surface of the sheet-like graphite layer 10, respectively, and the sheet-like elastomer layers 14 and 14'are laminated on at least one of the sheet-like elastomer layers 14 and 14'. Is roughly configured by blending the heat conductive filler 15.

【0026】

First, as the sheet-shaped graphite layer 10, various conventionally known graphite sheets can be appropriately selected and used. For example, those derived from natural graphite, those derived by graphitizing a polymer compound, and the like can be mentioned, and the origin of their production does not matter. The sheet-shaped graphite layer preferably has flexibility. The thickness of the sheet-shaped graphite layer can be appropriately set as needed, but in general, 0.1 to 1.6 mm is suitable. Further, the density of the sheet-shaped graphite layer is not particularly limited, but it is preferable that the density is lower than that of general graphite in consideration of the stress applied when deforming along the attachment target portion. Specifically, 0.5 ~ 1.5g / cm³, Especially 0.6 ~ 0.8g / cm³It is preferable to set the degree.

【0027】

Further, the surface of the sheet-shaped graphite layer 10 can be preliminarily coated with a primer in order to improve the adhesiveness with the woven fabric or the non-woven fabric 11 or the sheet-shaped elastomer layer 14', if necessary. Examples of this primer include Primer C (trade name; manufactured by Shinetsu Silicone), Primer X (trade name; manufactured by Toray Dow Corning Silicone), Primer Y (trade name; manufactured by Toray Dow Corning Silicone), ME151 (trade name; manufactured by Toshiba Silicone Co., Ltd.) and the like can be mentioned.

【0028】

The woven fabric or non-woven fabric 11 to be attached to the sheet-shaped graphite layer 10 is appropriately selected from various synthetic fibers, natural fibers, glass fibers, metal fibers and other woven fabrics and non-woven fabrics in consideration of heat resistance during use. It can be selected and used. However, if the side to which the woven fabric or the non-woven fabric 11 is attached (the sheet-like elastomer layer 14 side in FIG. 1) is the side to be attached to an electric / electronic device or the like, the woven fabric or the non-woven fabric 11 shall have electrical insulation. Is preferable. As a preferable example of such a woven fabric / non-woven fabric, a non-woven fabric made of aramid fibers such as Meta-Aramid Paper (trade name; manufactured by DuPont Teijin Advanced Paper Co., Ltd.) can be mentioned. Further, if the thickness of the woven fabric or the non-woven fabric is too thick, the thermal conductivity of the entire heat conductive sheet decreases, and conversely, if it is too thin, the reinforcing effect on the sheet-shaped graphite layer 10 cannot be sufficiently obtained. It is set appropriately in consideration. Specifically, the basis weight is 10 to 30 g / m.², Especially 12-18g / m²Is appropriate.

【0029】

Subsequently, the woven fabric or the non-woven fabric 11 is attached to the sheet-shaped graphite layer 10 with the adhesive 13, and the present invention is characterized in that the adhesive 13 contains the thermally conductive additive 12. To do. As a result, since the additive 12 is responsible for heat conduction, the overall heat conductivity does not decrease even if the woven fabric or the non-woven fabric 11 is present, and high heat dissipation can be obtained. As the additive 12, any substance that can be dispersed in the adhesive 13 and has a relatively high thermal conductivity can be used. Specific examples include carbon powder such as carbon black and graphite, aluminum nitride, boron nitride and the like, and the particle size thereof is not limited to these, but the particle size thereof is the thickness of the woven fabric or the non-woven fabric 11. It is preferable to have a particle size of about.

【0030】

Further, the amount of the additive 12 added can be appropriately set within a range that does not impair the adhesiveness of the woven fabric or the non-woven fabric 11 to the sheet-shaped graphite layer 10. However, when a conductive additive such as carbon black is used, if the amount added is too large, the thermal conductivity will increase, but the electrical insulation will decrease, and the sheet will be attached to electronic components. In general, it is not desirable, so it is set appropriately in consideration of these balances. Specifically, although it varies depending on the type of the additive 12, for example, in the case of carbon black, it is preferably about 20 to 40% by weight, especially about 25 to 35% by weight, based on the adhesive 13.

【0031】

As the adhesive 13, various adhesives are appropriately selected and used. Further, it is preferable that the adhesive used has heat resistance and a small coefficient of thermal expansion. Examples of such adhesives include polyimide adhesives such as Jupitite (trade name; manufactured by Ube Kosan Co., Ltd.) and Capton (trade name; manufactured by Toray DuPont), KE1800T (trade name; manufactured by Shinetsu Silicone Co., Ltd.), Examples include, but are not limited to, silicone-based adhesives such as YR3232 (trade name; manufactured by GE Toshiba Silicone Co., Ltd.), epoxy resin-based adhesives, acrylic resin-based adhesives, and the like.

【0032】

When the woven fabric or the non-woven fabric 11 is attached to the sheet graphite 10, it can be attached by a general method. That is, the adhesive 13 in which the additive 12 is dispersed in advance is applied to the surface of the sheet-shaped graphite layer 10, and then the woven fabric or the non-woven fabric 11 is laminated, and if necessary, added by a roll or a flat plate press or the like. The adhesive may be cured while pressing. Alternatively, the adhesive 13 containing the additive 12 may be applied to or impregnated with the woven fabric or the non-woven fabric 11, and the adhesive 13 may be laminated and attached to the sheet-shaped graphite layer 10.

【0033】

By attaching the woven fabric or the non-woven fabric 11, the sheet-shaped graphite layer 10 is reinforced, and as a result, it is possible to prevent cleavage or chipping of the sheet-shaped graphite 10 that occurs when the heat conductive sheet 1 is deformed. .. Further, in the manufacturing process of the heat conductive sheet 1, it is possible to avoid a situation in which the sheet-shaped graphite layer 10 is torn when an external force such as a winding tension is applied. Therefore, the heat conductive sheet 1 can be manufactured as a continuous sheet, and mass productivity is improved. As described above, despite the fact that the woven fabric or the non-woven fabric 11 is attached, the overall thermal conductivity is maintained high due to the additive 12.

【0034】

Next, the sheet-like elastomer layer 14 (including the sheet-like elastomer layer 14'unless otherwise specified) will be described. As the elastomer constituting the sheet-shaped elastomer layer 14, various conventionally known elastomers can be appropriately selected and used. Specific examples include silicone rubber, acrylic rubber, urethane rubber, butyl rubber, chloroprene rubber and the like. Among these, silicone rubber having excellent heat resistance is particularly preferably used.

【0035】

As the silicone rubber, for example, a heat-curing type or a room temperature curing type, a condensation type or an addition type, or the like can be used. Further, the group bonded to the silicon atom is not particularly limited, and examples thereof include an alkyl group such as a methyl group, an ethyl group and a propyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a vinyl group and an allyl group. In addition to aryl groups such as alkenyl groups, phenyl groups, and tolyl groups, those in which the hydrogen atom of these groups is partially substituted with another atom or a bonding group can be mentioned. Among the above-mentioned various silicone rubbers, those having an additive curing mechanism do not generate by-products during curing and are preferably used in this respect.

【0036】

The silicone rubber may be in a gel state. For example, the degree of needle insertion of JIS K 2207-1980 (50 g load) after curing is 5 to 200, especially when the heat conductive filler described later is not blended. It is preferable to use one of 80 to 120. When a silicone rubber having such a softness is used, the adhesion of the sheet-like elastomer layer 14 is increased, which is convenient when attaching the heat conductive sheet.

【0037】

In general, some commercially available elastomers such as silicone rubber are shipped to the market in a form containing a filler, a plasticizer, other additives, etc., and these elastomers also have the object of the present invention. It can be used as appropriate within a range that does not impair.

【0038】

Then, the heat conductive filler 15 is blended in at least one of the sheet-shaped elastomer layers 14 and 14'. That is, although FIG. 1 shows an example of blending with both the sheet-shaped elastomer layers 14 and 14', it may be blended only with the sheet-shaped elastomer layer 14 or only with the sheet-shaped elastomer layer 14'. It may be blended. As the heat conductive filler 15, it can be appropriately selected and used from various conventionally known heat conductive substances. Examples thereof include nitrides such as soft magnetic or hard soft magnetic ferrite, aluminum nitride, silicon nitride, boron nitride, titanium nitride, zirconium nitride, aluminum oxide (alumina), silicon oxide, boron oxide, titanium oxygen, zirconium oxide and the like. Examples thereof include oxides, carbon nanotubes, carbon microcoils, pure iron, metallic silicon, aluminum, gold, silver and copper. A plurality of types of these thermally conductive fillers can be used in combination as required. However, when a thermally conductive filler is mixed with the sheet-like elastomer layer to be attached to an electronic component or the like, an electrically insulating thermally conductive filler (ferrite, nitride, oxide, etc. among the above) is used. ) Is preferably selected and blended. The blending amount of the heat conductive filler can be appropriately set as needed, but in general, in order to impart sufficient heat conductivity to the sheet-shaped elastomer layer and ensure good moldability, the sheet-shaped elastomer layer is formed. 20 to 90% by weight is suitable with respect to the total weight of the elastomer layer.

【0039】

As for the above-mentioned soft magnetic ferrite, Mn-Mg-based, Ni-Zn-based, Cu-Zn-based and other soft magnetic ferrites are known, and any of these can be applied. Among them, Ni- Zn-based soft magnetic ferrite is particularly preferably used because it has a correspondingly high thermal conductivity, is less likely to cause curing inhibition when silicone rubber is used, and has excellent dispersibility in silicone rubber. Be done. Soft magnetic ferrite is economical because it can be obtained at a much lower price than a high thermal conductive filler such as boron nitride.

【0040】

In addition, the above-mentioned carbon nanotubes are generally made of carbon, have an outer diameter of 2 to 70 nm, and have a length of 10²It is a cylindrical hollow fiber-like substance that is more than doubled, and can be obtained by a gas phase decomposition reaction of a carbon-containing gas, an arc discharge method using a carbon rod, carbon fibers, or the like. Further, the terminal shape is known to be cylindrical or conical, but any of them can be applied. Further, the ends may be closed or open. Examples of preferably used carbon nanotubes include Graphite Fibrils and Grades BN (trade name; manufactured by Hyperion Catalysis International Co., Ltd.).

【0041】

Further, the above carbon microcoils are generally made of carbon, have a fiber diameter of 0.05 to 5 μm, a coil outer diameter of 2 to 10 times the fiber diameter, and a number of turns of 5 / coil outer diameter (μm) to 50 per 10 μm. / A coiled fiber material having a coil outer diameter (μm), which can be obtained by a vapor phase decomposition reaction of a carbon-containing gas.

【0042】

Carbon nanotubes and carbon microcoils have thermal conductivity and are also excellent in electromagnetic wave absorption. Therefore, the thermally conductive sheet in which these are blended in the sheet-like elastomer layer can exhibit electromagnetic wave absorption having a high SN ratio. In addition, the blending amount of carbon nanotubes and carbon microcoils is very expensive due to the fact that the total production of these is still small, so the blending amount is set to about 0.05 to 10% by weight with respect to the total weight of the sheet-like elastomer layer. It is preferable to use other thermally conductive fillers in combination.

【0043】

As for the various heat conductive fillers described above, any shape such as spherical, fibrous, and indefinite can be adopted. The size thereof can be appropriately set, but in general, a spherical shape having a particle size of about 3 to 50 μm and particularly a particle size of 10 to 20 μm is preferable from the viewpoint of improving dispersibility.

【0044】

Further, when silicone rubber is particularly used as the material of the sheet-like elastomer layer 14, the surface of the thermally conductive filler 15 is, if necessary, in order to further enhance the affinity with the silicone rubber and uniformly disperse it. It can be treated with a silane coupling agent. Examples of this silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysila, vinyltrimethoxysilane, vinyl tris (β-methoxyethoxy) silane, and γ-methacryloxypropyltrimethoxysilane. β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-crisidexypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl)- Examples thereof include γ-aminopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane. The amount of the silane coupling agent used can be appropriately set as needed, but in general, about 0.2 to 10% by weight is appropriate with respect to the weight of the heat conductive filler.

【0045】

Further, when the heat conductive filler 15 is blended with both the sheet-shaped elastomer layers 14 and 14', the composition such as the type and amount of the filler to be blended is determined by both the sheet-shaped elastomer layers 14 and 14'. It can be the same or different. As a specific example of different cases, only electrically insulating soft magnetic ferrite is blended in the sheet-like elastomer layer on the side to be attached to an electronic device such as an IC chip, and the other is connected to the open side or the heat radiation fin or the like. When carbon nanotubes are blended in the sheet-like elastomer layer on the side of the surface in order to impart an electromagnetic wave absorption effect, and the like can be mentioned.

【0046】

In addition to the heat conductive filler 15, the sheet-shaped elastomer layer 14 is provided with a curing agent, a curing accelerator, and a coloring agent generally used for elastomers as long as the object of the present invention is not impaired. An appropriate amount of agent, flame-retardant material, etc. can be blended.

【0047】

The sheet-shaped elastomer layer 14 (14') can be laminated on the woven fabric or the non-woven fabric 11 or the sheet-shaped graphite layer 10 by a general method. That is, to explain the case of blending the heat conductive filler, first, the heat conductive filler and general additives to be used as needed are mixed with the stock solution of the uncured and fluid elastomer. To prepare a thermally conductive elastomer composition. The elastomer composition can be prepared by adding the above-mentioned filler or the like to the elastomer stock solution and appropriately mixing the mixture with, for example, a Henschel mixer, a Banbury mixer, a three-roll kneader or the like. Then, this elastomer composition is poured onto the above-mentioned woven fabric or non-woven fabric 11 or onto the sheet-like graphite layer 10, and the poured elastomer composition is cured to obtain the desired thermally conductive sheet 1. .. Here, the casting of the elastomer composition can be performed by using a known means such as a spray method, a dipping method, a calendering method, and a wire bar coating method.

【0048】

When the poured elastomer composition is cured, it is preferable to perform it while applying pressure. According to the present inventor, it is unavoidable that bubbles are generated in the process of forming the sheet-like elastomer layer, but it has been found that the presence of these bubbles slightly lowers the thermal conductivity. Further, if a gap is formed between the sheet-shaped graphite layer 10 and the sheet-shaped elastomer layer 14', or between the woven fabric or the non-woven fabric 11 and the sheet-shaped elastomer layer 14, the overall thermal conductivity also decreases. By pressurizing, the above-mentioned defects such as air bubbles and voids can be removed, and the thermal conductivity can be further improved. Pressurization can be performed while appropriately heating with various press machines such as rolls and flat plate presses. Alternatively, when squeezing the poured elastomer composition to develop it to a uniform thickness, the squeezing pressure may be used to pressurize the composition.

【0049】

The pressure to pressurize is appropriately set according to the temperature at which the elastomer composition is cured, the concentration of the heat conductive filler, and the like, but if it is too low, the effect of bringing the layers into close contact and removing defects is insufficient, and vice versa. If it is too high, the heat conductive filler will be unevenly distributed, which is not preferable. Therefore, the balance thereof should be taken into consideration and set appropriately. Specifically, 10 ~ 30kgf / cm²Degree is preferable.

【0050】

The thickness of the sheet-like elastomer layer 14 can be appropriately set, but in order to ensure adhesion to the mounting target portion, the thickness after curing is preferably at least 80 μm or more, of which 0.1 ~ 1 mm is particularly preferable.

【0051】

Next, the embodiment (2) of the present invention is shown in FIG. In the heat conductive sheet 1 of FIG. 2, a woven fabric or a non-woven fabric 11 is attached to one surface of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. A sheet-like elastomer layer 14 is laminated on the other surface of the sheet-like graphite layer 10, and a heat conductive filler 15 is blended in the sheet-like elastomer layer 14. This embodiment has an advantage of being excellent in thermal conductivity because it can be formed thinner as a whole as compared with the above-described embodiment (1). Further, in the heat conductive sheet 1 of FIG. 2, the surface to be attached to the electronic component or the like is the sheet-like elastomer layer 14 side.

【0052】

Further, FIG. 3 shows the embodiment (3) of the present invention. In the thermally conductive sheet 1 of FIG. 3, a woven fabric or a non-woven fabric 11 is thermally conductive on one surface of the sheet-like graphite layer 10. It is attached by an adhesive 13 containing the additive 12 of the above. Further, the sheet-like elastomer layer 14 is laminated on the woven fabric or the non-woven fabric 11, and the heat conductive filler 15 is blended in the sheet-like elastomer layer 14. In this embodiment, as in the embodiment (2), the overall thickness is reduced, so that the heat conductivity is excellent. Further, since a part of the sheet-shaped elastomer layer 14 is impregnated in the woven fabric or the non-woven fabric 11, the adhesion between the sheet-shaped elastomer layer 14 and the woven fabric or the non-woven fabric 11 can be further strengthened by the so-called anchor effect. ..

【0053】

Further, FIG. 4 shows an embodiment (4) of the present invention. In the heat conductive sheet 1 of FIG. 4, a woven fabric or non-woven fabrics 11 and 11'are attached to both sides of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. Then, the sheet-like elastomer layers 14 and 14'are laminated on both the woven fabric and the non-woven fabrics 11 and 11', and the heat conductive filler 15 is blended in both the sheet-like elastomer layers 14 and 14', respectively. There is. The thermally conductive filler 15 can be blended in both the sheet-shaped elastomer layers 14 and 14'as shown in FIG. 4, or can be blended in only one of them. In this embodiment, unlike the above-described embodiments (1) to (3), the woven fabric or the non-woven fabrics 11 and 11'are attached to both sides of the sheet-shaped graphite layer 10, so that the sheet-shaped graphite layer 10 is attached. Is reinforced more effectively and cleavage is strongly prevented.

【0054】

Further, an embodiment (5) of the present invention is shown in FIG. In the heat conductive sheet 1 of FIG. 5, a woven fabric or non-woven fabrics 11 and 11'are attached to both sides of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. Then, a sheet-like elastomer layer 14'is laminated on either one of the woven fabric or the non-woven fabric 11 or 11'(in the case of FIG. 5, the woven fabric or the non-woven fabric 11'), and the sheet-like elastomer layer 14'is laminated. Contains the thermally conductive filler 15. In this embodiment, similarly to the above-described embodiment (4), the woven fabric or the non-woven fabrics 11 and 11'are attached to both sides of the sheet-shaped graphite layer 10, so that the reinforcing effect on the sheet-shaped graphite layer 10 is achieved. Is large. In addition, since the overall thickness is reduced, it is also excellent in thermal conductivity.

【0055】

The sheet-like graphite layer 10, the woven fabric or the non-woven fabric 11, the additive 12, the adhesive 13, the sheet-like elastomer layer 14, the heat conductive filler 15, and the like in the above embodiments (2) to (5). Each configuration, the manufacturing process of the heat conductive sheet 1, and the like are the same as those in the above embodiment (1).

【0056】

Subsequently, the embodiment (6) of the present invention is shown in FIG. In the heat conductive sheet 1 of FIG. 6, a woven fabric or a non-woven fabric 11 is attached to one surface of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. Further, a sheet-like elastomer layer 14 is further laminated on the woven fabric or the non-woven fabric 11, and the heat conductive filler 15 is blended in the sheet-like elastomer layer 14. Then, a hole 16 is formed in communication between the sheet-shaped graphite layer 10 and the woven fabric or the non-woven fabric 11, and the elastomer protrusion 17 protruding from the sheet-shaped elastomer layer 14 is fitted in the hole 16. With this configuration, the sheet-like elastomer layer 14 is integrally adhered to the sheet-like graphite layer 10 and the woven fabric or the non-woven fabric 11, so that peeling between the layers can be more reliably prevented.

【0057】

The holes 16 are preferably formed so as to penetrate from the woven fabric or the non-woven fabric 11 to the sheet-shaped graphite layer 10, but as another case, the holes are formed halfway in the thickness direction of the sheet-shaped graphite layer 10. It can also be configured. In that case, the depth of the holes 16 in the middle can be set as appropriate, but it is preferable to form the holes 16 deeper than half the thickness of the sheet-shaped graphite layer 10. Further, the holes 16 can be formed by a general method. For example, punching such as perforation or needles is performed on a laminated body in which a woven fabric or a non-woven fabric 11 is attached to a sheet-shaped graphite layer 10. It can be carried out by appropriately adopting a known drilling means such as a water jet or a laser. Further, the number of holes 16, the horizontal cross-sectional shape, or the size can be appropriately set as needed. Generally, the number of holes is 1 to 20 / cm²The horizontal cross-sectional shape of the hole is preferably circular, and the size of the hole is preferably 0.2 to 2 mm in diameter.

【0058】

Further, as shown in FIG. 6, it is preferable that the woven fabric or the non-woven fabric 11 is inserted along the holes 16 formed in the sheet-shaped graphite layer 10. As a result, the sheet-shaped graphite layer 10 and the woven fabric or the non-woven fabric 11 can be integrated to further improve the stacking maintenance strength.

【0059】

When producing the thermally conductive sheet 1 as shown in FIG. 6, generally, the elastomer composition before curing is allowed to flow into the holes 16 formed in the sheet-like graphite layer 10, and then the elastomer composition is prepared. Can be obtained by curing the graphite to form the protrusion 17. That is, an uncured elastomer composition containing a heat conductive filler 15 or the like is poured onto a laminate of a sheet-shaped graphite layer 10 and a woven fabric or a non-woven fabric 11 having a large number of holes, and the mixture is appropriately added. It can be produced by flowing the elastomer composition into the pores 16 while pressing and curing the composition.

【0060】

Next, FIG. 7 shows an embodiment (7) of the present invention. In the heat conductive sheet 1 of FIG. 7, a woven fabric or a non-woven fabric 11 is attached to one surface of the sheet-shaped graphite layer 10 with an adhesive 13 containing a heat conductive additive 12. Further, the sheet-like elastomer layers 14 and 14'are further laminated on the other surface of the woven fabric or the non-woven fabric 11 and the sheet-like graphite layer 10, respectively, and the sheet-like elastomer layers 14 and 14'are thermally conductively filled. Material 15 is blended. Further, a hole 16 is formed so as to penetrate the sheet-shaped graphite layer 10 and the woven fabric or the non-woven fabric 11, and the elastomer protrusion 17 protruding from the sheet-shaped elastomer layers 14 and 14 is fitted into the hole 16. There is. Then, the sheet-like elastomer layers 14 and 14'are integrally bonded to each other via the protrusions 17. With this configuration, the sheet-shaped graphite layer 10, the woven fabric or the non-woven fabric 11, and the sheet-shaped elastomer layers 14 and 14'are completely integrated and adhere to each other, so that peeling between layers can be reliably prevented. The thermally conductive filler 15 may be blended in both the sheet-shaped elastomer layers 14 and 14'as shown in FIG. 7, but may be blended in only one of them. Further, the woven fabric or the non-woven fabric 11 may be attached only to one surface of the sheet-shaped graphite layer 10 as shown in FIG. 7, or may be attached to both sides of the sheet-shaped graphite layer 10.

【0061】

In addition, in the above-described embodiments (6) and (7), the sheet-like graphite layer 10, the woven fabric or the non-woven fabric 11, the additive 12, the adhesive 13, the sheet-like elastomer layer 14, the heat conductive filler 15, etc. The configuration of the above, and the manufacturing process other than the portion related to the hole 16 are the same as those of the above embodiment (1).

【0062】

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. (Example 1) First, the basis weight is 15 g / m.²Polyethylene non-woven fabric, thickness 0.3 mm, density 0.7 g / cm³It was attached to one side of Nika film (trade name; manufactured by Nippon Carbon Co., Ltd.), which is a sheet-like graphite layer of. A silicone-based adhesive YR3232 (trade name; manufactured by GE Toshiba Silicone Co., Ltd.) is used as the adhesive used for sticking, and the adhesive contains 30% by weight of carbon powder in advance with respect to the adhesive. I let you. Next, for silicone gel CF5057 (trade name; manufactured by Toray Dow Corning Silicone Co., Ltd.) with a needle insertion degree of 100 in JIS K 2207-1980 (50 g load), an irregular shape with an average particle size of 16 μm as a heat conductive filler. Ni-Zn-based soft magnetic ferrite powder (manufactured by Powder Tech Co., Ltd.) was mixed in a three-roll kneader at room temperature to prepare a composition. The blending amount of the soft magnetic ferrite powder was 83% by weight with respect to the silicone gel. Next, after vacuum defoaming, this composition was poured into both sides of the laminate of the above-mentioned non-woven fabric and the sheet-shaped graphite layer so as not to entrain air, and a glass having spacers interposed at the four corners from above. Cover with a plate and 20kgf / cm for 30 minutes at 100 ° C.²The heating press was performed at the pressure of. After confirming that the silicone gel composition had hardened, the glass plate was removed to obtain the desired heat conductive sheet. The thickness of the cured layer of the silicone gel composition was 100 μm on both sides.

【0063】

The obtained thermal conductivity sheet was measured for thermal conductivity using a thermal conductivity meter QTM500 (trade name; manufactured by Kyoto Denshi Kogyo Co., Ltd.). As a result, the thermal conductivity was 6.3 W / mK, which was about twice as high as that of Comparative Example 1 described later. Furthermore, when the obtained thermally conductive sheet was cut by punching with a press, there was no cleavage or lack of graphite from the cut surface of the sheet-like graphite layer as seen when the non-woven fabric was not attached. I couldn't see it. Furthermore, in order to evaluate the handleability of the heat conductive sheet during manufacturing, a) hold both ends of one short side of the long heat conductive sheet (1 m x 40 cm) by hand, and hold the heat conductive sheet by its own weight. Suspended. As a result, no cracks were observed in the sheet-like graphite layer, and no cleavage was observed from each layer. In addition, b) Grasp the midpoints of the two opposing short sides of the long heat conductive sheet by hand, bring the opposing short sides close to each other to about 30 cm, and slacken the center of the heat conductive sheet. It was. As a result, no cracks were found in the sheet-like graphite layer at the free bending portion, and no cleavage was observed from each layer.

【0064】

(Example 2) In Example 1 above, in addition to the Ni-Zn-based soft magnetic ferrite powder, 1% by weight of Graphite Fibrils / Grades BN (trade name; manufactured by Hyperion Catalyz International), which is a carbon nanotube, was blended. Except for the above, a thermally conductive sheet was prepared in the same manner as in Example 1 above. Next, a simple electromagnetic wave detector that notifies the strength of electromagnetic waves by the number of LED blinks and electronic sound is placed in front of the CRT connected to the computer, and the LED blinks when the heat conductive sheet obtained during this time is inserted and removed. When the difference in the number and the intensity of the electronic sound was examined, it was found that this heat conductive sheet was also excellent in electromagnetic wave absorption.

【0065】

(Comparative Example 1) A thermally conductive sheet was obtained in the same manner as in Example 1 above, except that the adhesive used for attaching the non-woven fabric did not contain carbon black powder. When the thermal conductivity of the obtained heat conductive sheet was measured by the same method as in Example 1 above, it was only 2.43 W / mK.

【0066】

(Example 3) First, the basis weight is 15 g / m.²Polyethylene non-woven fabric, thickness 0.3 mm, density 0.7 g / cm³It was attached to one side of Nika film (trade name; manufactured by Nippon Carbon Co., Ltd.), which is a sheet-like graphite layer of. A silicone-based adhesive YR3232 (trade name; manufactured by GE Toshiba Silicone Co., Ltd.) is used as the adhesive used for sticking, and the adhesive contains 30% by weight of carbon powder in advance with respect to the adhesive. I let you. Next, make 9 circular holes with a diameter of 0.8 mm / cm.²The pores were perforated together with the sheet-like graphite layer and the non-woven fabric at equal intervals in the thickness direction. Subsequently, aluminum nitride powder having an average particle size of 10 μm as a heat conductive filler was mixed with the same silicone gel as in Example 1 at room temperature in a three-roll kneader to prepare a composition. The blending amount of the aluminum nitride powder was 75% by weight based on the silicone gel. Next, after vacuum defoaming, this composition was poured into both sides of the laminate of the above-mentioned non-woven fabric and the sheet-shaped graphite layer so as not to entrain air, and a glass having spacers interposed at the four corners from above. Cover with a plate and 20kgf / cm for 30 minutes at 100 ° C.²The heating press was performed at the pressure of. After confirming that the silicone gel composition had hardened, the glass plate was removed to obtain the desired heat conductive sheet.

【0067】

As a result of visually observing the appearance and cut cross section of the obtained heat conductive sheet, the composition of the poured silicone gel was cured while flowing along the through holes formed in the sheet-like graphite layer and the non-woven fabric, and the protrusions were formed. The silicone gel layers on the front and back sides were integrally bonded via protrusions in the through holes. In addition, the non-woven fabric entered along the through hole.

【0068】

When the thermal conductivity of the above-mentioned thermal conductivity sheet was measured in the same manner as in Example 1 above, it was 6.8 W / mK, which was a very high value. In addition, when it was repeatedly bent with fingers assuming use, the silicone gel layer did not peel off from the sheet-like graphite layer after several tens of times, and the sheet-like graphite layer itself also peeled off between layers. I didn't do it.

【0069】

[Effect of the invention]

As described above, in the heat conductive sheet of the present invention, since the woven fabric or the non-woven fabric is attached to the sheet-shaped graphite layer, the sheet-shaped graphite layer is reinforced. As a result, when the heat conductive sheet is deformed, defects such as cleavage do not occur in the sheet-like graphite layer, and the reliability is excellent. Further, since the sheet-like graphite layer is not torn even when the take-up tension is applied, the heat conductive sheet can be manufactured as a continuous sheet, and the mass productivity is also excellent. The greatest feature of the present invention is that the adhesive used to attach the woven fabric or the non-woven fabric contains an additive such as carbon powder, so that the thermal conductivity is lowered even if the woven fabric or the non-woven fabric is present. It is possible to exhibit high thermal conductivity as a whole.

【0070】

In addition, since the woven fabric or non-woven fabric and the sheet-shaped graphite layer are communicated with each other to form holes and the protrusions of the sheet-like elastomer layer are fitted into the holes, the respective layers are integrally adhered to each other to prevent delamination. Can be done.

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing of the heat conductive sheet in Embodiment (1) of this invention.

[Figure 2]

It is sectional drawing of the heat conductive sheet in Embodiment (2) of this invention.

[Fig. 3]

It is sectional drawing of the heat conductive sheet in Embodiment (3) of this invention.

[Fig. 4]

It is sectional drawing of the heat conductive sheet in Embodiment (4) of this invention.

[Fig. 5]

It is sectional drawing of the heat conductive sheet in Embodiment (5) of this invention.

[Fig. 6]

It is sectional drawing of the heat conductive sheet in Embodiment (6) of this invention.

[Fig. 7]

It is sectional drawing of the heat conductive sheet in Embodiment (7) of this invention.

[Explanation of symbols]

1 Thermal conductive sheet 10 Sheet graphite layer 11 Woven fabric or non-woven fabric 11'Woven fabric or non-woven fabric 12 Additives 13 Adhesive 14 Sheet-like elastomer layer 14'Sheet-like elastomer layer 15 Thermally conductive filler 16 holes 17 protrusions