JP6986648B2 - Heat conduction sheet and its manufacturing method, heat dissipation structure and electronic equipment - Google Patents

Description

The present invention relates to a heat conductive sheet and a method for manufacturing the heat conductive sheet, as well as a heat dissipation structure and an electronic device.

Conventionally, semiconductor elements mounted on various electric devices such as personal computers and other devices generate heat by driving, and the accumulated heat causes adverse effects on the driving of semiconductor elements and peripheral devices. , Various cooling methods are used.

As a cooling method for a device having a semiconductor element, a method of attaching a fan to the device to cool the air inside the device housing and a method of attaching a heat sink such as a heat radiating fin or a heat sink to the semiconductor element to be cooled are known. Has been done. In the above-mentioned method of attaching a heat sink to a semiconductor element for cooling, a heat conductive sheet is provided between the semiconductor element and the heat sink in order to efficiently dissipate the heat of the semiconductor element.

As an example of such a heat conductive sheet, a cured product of a silicone resin is used as a binder component, and an unreacted silicone resin is leaked from the heat conductive sheet by a press in order to improve adhesion to a heating element and a heat radiating member to surface the surface. Proposed ones are coated to impart adhesiveness and improve adhesion (see, for example, Patent Document 1).

Japanese Patent No. 5722299

However, as in the technique described in Patent Document 1, although the tack property (adhesiveness) generated by bleeding has a tack property that can be fixed in position at the time of mounting, the heat conductive sheet is fixed when the mounted component is inverted. There is a problem that it is not possible to obtain the level of tackiness that can be achieved. Further, the present inventor has a problem that the tack force decreases with time when the heat conductive sheet comes into contact with air, and the heat conductive sheet is displaced when the heat conductive sheet is placed between the heating element and the heat radiating member. Found.
An object of the present invention is to solve the above-mentioned problems in the prior art and to achieve the following objects. That is, an object of the present invention is to provide a heat conductive sheet having sufficient tackiness based on handling at the time of mounting, a method for manufacturing the same, a heat dissipation structure, and an electronic device.

The means for solving the above problems are as follows. That is,
<1> A heat conductive sheet made of a cured product of a resin composition containing carbon fibers, an inorganic filler other than the carbon fibers, and a binder resin.
It is a heat conduction sheet characterized by satisfying the following (1) and (2).
(1) The heat conductive sheet sandwiched between the release films is pressed at 0.5 MPa for 30 seconds, and immediately after the release film is peeled off, the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm. The tack force on the surface of the heat conductive sheet when peeled off at 10 mm / sec is 100 gf or more.
(2) The tack force A (gf) on the surface of the heat conductive sheet immediately after the press treatment of the above (1) was performed and the release film was peeled off, and the heat conductive sheet was pressed and then exposed to the atmosphere for 1 hour. Later, the tack force B (gf) on the surface of the heat conductive sheet when the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec was calculated by the following equation (B /). A) × 100 ≧ 80%.
<2> Further, (3) immediately after slicing the heat conductive sheet, the heat conduction sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec. The heat conductive sheet according to <1>, wherein the tack force on the surface of the sheet is 20 gf or less.
<3> The heat conductive sheet according to any one of <1> to <2>, wherein the shore OO hardness of the heat conductive sheet is 40 or more and 70 or less.
<4> The inorganic filler other than carbon fiber, aluminum oxide specific surface area of more than 1.4 m ² / g or a specific surface area of 1.4 m ² / g or more aluminum nitride, and any one of aluminum hydroxide, at least The heat conductive sheet according to any one of <1> to <3>, which comprises.
<5> The heat conductive sheet according to any one of <1> to <4>, wherein the inorganic filler other than carbon fiber contains either aluminum oxide or aluminum nitride and aluminum hydroxide.
<6> The heat conduction according to any one of <4> to <5>, wherein the specific surface area of either the aluminum oxide or the aluminum nitride is 1.4 m ² / g or more and 3.3 m ^{2 / g or less.} It is a sheet.
<7> The heat conductive sheet according to any one of <1> to <6>, wherein the volume average particle size of the inorganic filler other than carbon fibers is 0.4 μm or more and 2 μm or less.
<8> The heat conductive sheet according to <7>, wherein the volume average particle diameter of the inorganic filler other than carbon fibers is 0.7 μm or more and 2 μm or less.
<9> The heat conductive sheet according to any one of <1> to <8>, wherein the binder resin is a silicone resin.
<10> The method for producing the heat conductive sheet according to any one of <1> to <9>.
A molding body manufacturing step of obtaining a molded body of the resin composition by molding a resin composition containing a binder resin, carbon fibers, and an inorganic filler other than the carbon fibers into a predetermined shape and curing the resin composition.
The step of producing a molded body sheet by cutting the molded body into a sheet to obtain a molded body sheet, and
It is a method for manufacturing a heat conductive sheet, which comprises.
<11> A heat radiating structure comprising a heating element, the heat conductive sheet according to any one of <1> to <9>, and a heat radiating member in this order.
<12> An electronic device having the heat dissipation structure according to the above <11>.

According to the present invention, a heat conductive sheet having sufficient tackiness in consideration of handling at the time of mounting, a method for manufacturing the same, a heat radiating structure, and an electron, which can solve the above-mentioned problems in the prior art and achieve the above object. Equipment can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of the heat dissipation structure of the present invention.

(Heat conduction sheet)
The heat conductive sheet of the present invention is a cured product of a composition containing carbon fibers, an inorganic filler other than the carbon fibers, and a binder resin.

The heat conductive sheet of the present invention has both an oil bleeding mechanism and a mechanism for holding the bleeding oil on the sheet surface, so that sufficient tackiness is maintained on the surface of the heat conductive sheet for a long time. It is possible to fix it to an object to be bonded such as a body, and it is possible to reduce the risk of the heat conductive sheet falling even in an excessive operation such as a reversing process.

In the present invention, the heat conductive sheet is filled with the following (1) and (2), and preferably further filled with the following (3). As a result, sufficient tackiness is given to the surface of the heat conductive sheet, it is possible to fix it to an object to be bonded such as a heating element or a radiator, and there is no problem that the mounted parts will fall even if they are inverted, and at the time of mounting. A heat conductive sheet with sufficient tackiness can be realized based on handling.

(1) The heat conductive sheet sandwiched between the release films is pressed at 0.5 MPa for 30 seconds, and immediately after the release film is peeled off, the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm. The tack force on the surface of the heat conductive sheet when peeled off at 10 mm / sec is 100 gf or more, preferably 200 gf or more.
(2) The tack force A (gf) on the surface of the heat conductive sheet immediately after the press treatment of the above (1) was performed and the release film was peeled off, and the heat conductive sheet was pressed and then exposed to the atmosphere for 1 hour. Later, the tack force B (gf) on the surface of the heat conductive sheet when the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec was calculated by the following equation (B /). A) × 100 ≧ 80%, and the following equation, (B / A) × 100 ≧ 100% is preferable (hereinafter, it may be referred to as a retention rate of tack force after air exposure).
(3) Immediately after slicing the heat conductive sheet, the tack force on the surface of the heat conductive sheet when the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec. Is preferably 20 gf or less, more preferably 15 gf or less.

Here, the tack force in the above (1) to (3) is a value measured in the DEPTH mode using, for example, a tackine tester manufactured by Malcolm Co., Ltd. That is, it is the tack force on the surface of the heat conductive sheet when the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec.
"Immediately after peeling off the release film" in the above (1) and (2) means within 3 minutes from the time when the release film is peeled off.
As the release film, a film that has been mold-released with wax or the like is preferable.
In the above-mentioned (2), "exposure to the atmosphere for 1 hour", the exposure was carried out in the atmosphere at a temperature of 25 ° C.
“Immediately after slicing” in (3) above means within 5 minutes from the time when the heat conductive sheet is sliced.

The shore OO hardness of the heat conductive sheet is preferably 40 or more and 70 or less, and more preferably 45 or more and 60 or less.
When the shore OO hardness is 40 or more and 70 or less, the heat conductive sheet has sufficient flexibility, and the followability and adhesion to the surface of the electronic component and the heat spreader are good.
The shore OO hardness can be measured using, for example, an ASTM-D2240 compliant shore OO hardness tester.

<Carbon fiber>
The carbon fiber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, pitch-based carbon fiber, PAN-based carbon fiber, carbon fiber obtained by graphitizing PBO fiber, arc discharge method, laser evaporation method, etc. Examples thereof include carbon fibers synthesized by a CVD method (chemical vapor phase growth method), a CCVD method (catalytic chemical vapor phase growth method) and the like. These may be used alone or in combination of two or more. Among these, carbon fibers obtained by graphitizing PBO fibers, PAN-based carbon fibers, and pitch-based carbon fibers are preferable, and pitch-based carbon fibers are particularly preferable, from the viewpoint of thermal conductivity.

The average fiber diameter (average minor axis length) of the carbon fibers is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 4 μm or more and 20 μm or less, and more preferably 5 μm or more and 14 μm or less.
The average fiber length (average major axis length) of the carbon fibers is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 μm or more and 250 μm or less, more preferably 75 μm or more and 200 μm or less, and more preferably 90 μm. More than 170 μm or less is particularly preferable.

The thermal conductivity of the carbon fiber itself is appropriately selected according to the desired thermal conductivity of the heat conductive sheet, but is preferably 150 W / m · K or more and 1000 W / m · K or less.

If the content of the carbon fiber in the heat conductive sheet is too small, the heat conductivity tends to be low, and if it is too large, the viscosity tends to be high. Therefore, the content is preferably 15% by volume or more and 30% by volume or less.

<Inorganic fillers other than carbon fiber>
Inorganic filler other than carbon fiber has a specific surface area of 1.4 m 2 / ^g or more aluminum oxide or a specific surface area of 1.4 m 2 / ^g or more aluminum nitride, and may include at least one of aluminum hydroxide preferably , Aluminum oxide and aluminum nitride, and aluminum hydroxide are more preferably contained.
In the conventional technique, the tack property is exhibited by slicing and pressing the heat conductive sheet from the mold, but there is a problem that the tack force decreases with time when the sheet comes into contact with air.
In the present invention, preferably either aluminum oxide specific surface area as an inorganic filler other than carbon fibers or 1.4 m 2 / ^g or a specific surface area of 1.4 m 2 / ^g or more aluminum nitride, and aluminum hydroxide By including at least, the tackiness is not exhibited at the time of slicing treatment, and the strong tackiness is exhibited only when the surface of the heat conductive sheet is smoothed by the press treatment, so that the handling property is good, and the handling property is sufficient thereafter. The tackiness can be maintained.

Any of the specific surface area of aluminum oxide and aluminum nitride is preferably not less than ^{1.4m 2 / g, 1.4m 2 /} g or more 3.3 m ² / g or less is more preferable. When the specific surface area is 1.4 m ² / g or more, there is an advantage that the surface state of the heat conductive sheet can be made smoother after the press treatment.
The specific surface area can be measured by, for example, the BET method.

The shape, volume average particle size, and the like of the inorganic filler other than the carbon fiber are not particularly limited, and can be appropriately selected depending on the intended purpose. The shape is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include spherical, elliptical spherical, lumpy, granular, flat and needle-shaped. Among these, a spherical shape and an elliptical shape are preferable from the viewpoint of filling property, and a spherical shape is particularly preferable.

The volume average particle size of the inorganic filler other than the carbon fiber is preferably 0.4 μm or more and 2 μm or less, and more preferably 0.7 μm or more and 2 μm or less. When the volume average particle diameter is 0.4 μm or more and 2 μm or less, there is an advantage that the filler in the heat conductive sheet becomes dense and the tack holding ability of the sheet is improved.
The volume average particle diameter can be measured by, for example, a particle size distribution measuring device by a laser diffraction / scattering method or the like.

Inorganic fillers other than carbon fibers may be surface-treated. The surface treatment (for example, coupling treatment) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it is preferable to treat an inorganic filler other than carbon fiber with an alkoxysilane compound.
The treatment amount of the alkoxysilane compound is preferably 0.1% by volume or more and 4.0% by volume or less, and 1.5% by volume or more and 3.0% by volume or less with respect to the inorganic filler other than the carbon fiber. It is more preferable to have.

The alkoxysilane compound is a compound having a structure in which one to three of the four bonds of a silicon atom (Si) are bonded to an alkoxy group and the remaining bonds are bonded to an organic substituent. Examples of the alkoxy group contained in the alkoxysilane compound include a methoxy group, an ethoxy group, a protoxy group, a butoxy group, a pentoxy group, a hexatoxy group and the like. The alkoxysilane compound may be contained as a dimer in the heat conductive sheet.

Among the alkoxysilane compounds, an alkoxysilane compound having a methoxy group or an ethoxy group is preferable from the viewpoint of easy availability. The number of alkoxy groups contained in the alkoxysilane compound is preferably 3 from the viewpoint of enhancing the affinity with the heat conductive filler as an inorganic substance. The alkoxysilane compound is more preferably at least one selected from the trimethoxysilane compound and the triethoxysilane compound.

Examples of the functional group contained in the organic substituent of the alkoxysilane compound include an acryloyl group, an alkyl group, a carboxyl group, a vinyl group, a methacrylic group, an aromatic group, an amino group, an isocyanate group, an isocyanurate group and an epoxy group. Examples thereof include a hydroxyl group and a mercapto group. Here, when an addition reaction type organopolysiloxane containing a platinum catalyst is used as the precursor of the matrix, it is preferable to select and use an alkoxysilane compound that does not easily affect the curing reaction of the organopolysiloxane. Specifically, when an addition reaction type organopolysiloxane containing a platinum catalyst is used, the organic substituent of the alkoxysilane compound may not contain an amino group, an isocyanate group, an isocyanurate group, a hydroxyl group, or a mercapto group. preferable.

Since the alkoxysilane compound facilitates high filling of the inorganic filler other than the carbon fiber by increasing the dispersibility of the inorganic filler other than the carbon fiber, the alkylalkoxysilane compound having an alkyl group bonded to a silicon atom, that is, It is preferable to contain an alkoxysilane compound having an alkyl group as an organic substituent. The number of carbon atoms of the alkyl group bonded to the silicon atom is preferably 4 or more. Further, the number of carbon atoms of the alkyl group bonded to the silicon atom is preferably 16 or less from the viewpoint that the viscosity of the alkoxysilane compound itself is relatively low and the viscosity of the resin composition is kept low.

The alkoxysilane compound may be used alone or in combination of two or more.
Specific examples of the alkoxysilane compound include an alkyl group-containing alkoxysilane compound, a vinyl group-containing alkoxysilane compound, an acryloyl group-containing alkoxysilane compound, a methacrylic group-containing alkoxysilane compound, an aromatic group-containing alkoxysilane compound, and an amino group-containing alkoxysilane. Examples thereof include compounds, isocyanate group-containing alkoxysilane compounds, isocyanurate group-containing alkoxysilane compounds, epoxy group-containing alkoxysilane compounds, and mercapto group-containing alkoxysilane compounds.

Examples of the alkyl group-containing alkoxysilane compound include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, and n-propyltri. Examples thereof include ethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane and n-decyltrimethoxysilane. Among the alkyl group-containing alkoxysilane compounds, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, and n-decyltri. At least one selected from methoxysilane is preferred.

Examples of the vinyl group-containing alkoxysilane compound include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of the acryloyl group-containing alkoxysilane compound include 3-acryloyloxypropyltrimethoxysilane. Examples of the methacryl group-containing alkoxysilane compound include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane. Examples of the aromatic group-containing alkoxysilane compound include phenyltrimethoxysilane and phenyltriethoxysilane. Examples of the amino group-containing alkoxysilane compound include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyltri. Examples thereof include methoxysilane, 3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. Examples of the isocyanate group-containing alkoxysilane compound include 3-isocyanatepropyltriethoxysilane. Examples of the isocyanate group-containing alkoxysilane compound include tris- (trimethoxysilylpropyl) isocyanurate. Examples of the epoxy group-containing alkoxysilane compound include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycid. Examples thereof include xipropyltriethoxysilane. Examples of the mercapto group-containing alkoxysilane compound include 3-mercaptopropyltrimethoxysilane.

The content of the inorganic filler other than the carbon fiber is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 40% by volume or more and 80% by volume or less, and more preferably 45% by volume or more and 75% by volume or less. preferable. If the content is less than 40% by volume, the thermal resistance of the heat conductive sheet may increase, and if it exceeds 80% by volume, the flexibility of the heat conductive sheet may decrease.

<Binder resin>
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include thermoplastic resins, thermoplastic elastomers and thermosetting polymers.

Examples of the thermoplastic resin include ethylene-α-olefin copolymers such as polyethylene, polypropylene, and ethylene-propylene copolymer; polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinylacetate, and ethylene-vinyl acetate copolymer. Fluoropolymers such as coalesced, polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride, polytetrafluoroethylene; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene- Styrene copolymer (ABS) resin, polyphenylene-ether copolymer (PPE) resin, modified PPE resin, aliphatic polyamides, aromatic polyamides, polyimide, polyamideimide, polymethacrylic acid, polymethacrylic acid methyl ester, etc. Polymethacrylic acid esters: Polyacrylic acids, polycarbonates, polyphenylene sulfides, polysulfones, polyether sulfones, polyether nitriles, polyether ketones, polyketones, liquid crystal polymers, silicone resins, ionomers and the like. These may be used alone or in combination of two or more.

Examples of the thermoplastic elastomer include a styrene-butadiene block copolymer or a hydrogenated product thereof, a styrene-isoprene block copolymer or a hydrogenated product thereof, a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and a vinyl chloride-based heat. Examples thereof include a plastic elastomer, a polyester-based thermoplastic elastomer, a polyurethane-based thermoplastic elastomer, and a polyamide-based thermoplastic elastomer. These may be used alone or in combination of two or more.

Examples of the thermosetting polymer include crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, silicone resin, polyurethane, polyimide silicone, and thermosetting type. Examples thereof include polyimideene ether and thermosetting modified polyphenylene ether. These may be used alone or in combination of two or more.

Examples of the crosslinked rubber include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, and fluororubber. Examples thereof include urethane rubber, acrylic rubber, polyisobutylene rubber, and silicone rubber. These may be used alone or in combination of two or more.

Among these, a silicone resin is particularly preferable as the binder resin from the viewpoints of excellent molding processability and weather resistance, as well as adhesion and followability to electronic components.

The silicone resin is not particularly limited and may be appropriately selected depending on the intended purpose, but preferably contains a main agent of a liquid silicone gel and a curing agent. Examples of such a silicone resin include an addition reaction type silicone resin, a heat vulcanization type mirable type silicone resin using a peroxide for vulcanization, and the like. Among these, the addition reaction type silicone resin is particularly preferable because the adhesion between the heat generating surface and the heat sink surface of the electronic component is required.

As the addition reaction type silicone resin, a two-component addition reaction type silicone resin containing a polyorganosiloxane having a vinyl group as a main agent and a polyorganosiloxane having a Si—H group as a curing agent is preferable.

In the combination of the main agent of the liquid silicone gel and the curing agent, the blending ratio of the main agent and the curing agent is not particularly limited and may be appropriately selected depending on the intended purpose.

The content of the binder resin is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 25% by volume or more and 56% by volume or less, preferably 25% by volume or more, based on the total amount of the resin composition. More preferably, it is 40% by volume or less.

<Other ingredients>
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. For example, thixotropy-imparting agents, dispersants, curing accelerators, retarders, slight tackifiers, plasticizers, flame retardants, etc. Examples include antioxidants, stabilizers, colorants and the like.

(Manufacturing method of heat conductive sheet)
The method for producing a heat conductive sheet of the present invention preferably includes a molded body sheet manufacturing step, a molded body sheet manufacturing step, a resin composition preparation step, and a pressing step, and further, if necessary, other steps. include.
The method for manufacturing the heat conductive sheet is the method for manufacturing the heat conductive sheet of the present invention.
According to the method for manufacturing a heat conductive sheet of the present invention, since a strong tack is given to the surface of the heat conductive sheet, it is not necessary to use a separate adhesive, and labor saving and cost reduction in the manufacturing process can be realized. can.

<Resin composition preparation process>
The resin composition preparation step is a step of kneading a binder resin, carbon fibers, and an inorganic filler other than the carbon fibers to obtain a resin composition.

Examples of the binder resin include the binder resin exemplified in the description of the heat conductive sheet.
Examples of the carbon fiber include the carbon fiber exemplified in the description of the heat conductive sheet.
Examples of the inorganic filler other than carbon fibers include inorganic fillers other than carbon fibers exemplified in the description of the heat conductive sheet.
The kneading method is not particularly limited and can be appropriately selected according to the purpose.

<Molded body manufacturing process>
This is a step of obtaining a molded body of the resin composition by molding the resin composition into a predetermined shape and curing the resin composition.

The method for molding the resin composition into a predetermined shape in the molded body manufacturing step is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an extrusion molding method, a mold molding method and the like can be used. Can be mentioned.

The extrusion molding method and the mold molding method are not particularly limited, and the viscosity of the resin composition and the obtained heat conductive sheet are required from among various known extrusion molding methods and mold molding methods. It can be appropriately adopted depending on the characteristics to be applied.

The size and shape of the molded body (block-shaped molded body) can be determined according to the required size of the heat conductive sheet. For example, a rectangular parallelepiped having a vertical size of 0.5 cm or more and 15 cm or less and a horizontal size of 0.5 cm or more and 15 cm or less can be mentioned. The length of the rectangular parallelepiped can be determined as needed.

The curing of the resin composition in the molded body manufacturing step is preferably thermosetting. The curing temperature in the thermal curing is not particularly limited and may be appropriately selected depending on the intended purpose. For example, when the binder resin contains the main agent of the liquid silicone gel and the curing agent, the temperature is 60 ° C. or higher. It is preferably 120 ° C. or lower. The curing time in the heat curing is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.5 hours or more and 10 hours or less, for example.

<Molded body sheet manufacturing process>
The molded body sheet manufacturing step is a step of cutting the molded body into a sheet to obtain a molded body sheet, and can be performed by, for example, a slicing device.

The slicing device is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an ultrasonic cutter and a plane (plane). When the molding method is an extrusion molding method, the cutting direction of the molded body is preferably 60 degrees or more and 120 degrees or less, preferably 70 degrees or more, with respect to the extrusion direction because some of them are oriented in the extrusion direction. 100 degrees or less is more preferable, and 90 degrees (vertical) is particularly preferable.

The average thickness of the molded sheet is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 mm or more and 5.0 mm or less, and more preferably 0.2 mm or more and 1.0 mm or less.

<Press process>
The pressing step is a step of pressing the molded body sheet.
The press process can be performed, for example, by using a pair of press devices including a flat plate and a press head having a flat surface. Alternatively, a pinch roll may be used.

The pressure at the time of pressing is not particularly limited and can be appropriately selected depending on the purpose. However, if it is too low, the thermal resistance tends to be the same as that without pressing, and if it is too high, the sheet is stretched. Since there is a tendency, it is preferably 0.1 MPa or more and 100 MPa or less, and more preferably 0.5 MPa or more and 95 MPa or less.

The pressing time is not particularly limited and may be appropriately selected depending on the binder resin component, the pressing pressure, the sheet area, the exuding amount of the exuding component, and the like.

In the press process, in order to further promote the effect of exudation of the exudative component, a press head having a built-in heater may be used while heating. In order to enhance such an effect, it is preferable that the heating temperature is equal to or higher than the glass transition temperature of the binder resin. As a result, the pressing time can be shortened.

In the press treatment, by pressing the molded body sheet, the exuding component is exuded from the molded body sheet, and the sheet surface is covered with the exuding component. Therefore, the obtained heat conductive sheet can improve the followability and adhesion to the surface of the electronic component or the heat spreader, and can reduce the thermal resistance.

The molded body sheet is compressed in the thickness direction by being pressed, and the frequency of contact between the carbon fibers and the inorganic fillers other than the carbon fibers can be increased. This makes it possible to reduce the thermal resistance of the heat conductive sheet.

The press treatment is preferably performed using a spacer for compressing the molded body sheet to a predetermined thickness. That is, the heat conductive sheet can be formed to a predetermined sheet thickness according to the height of the spacer, for example, by arranging the spacer on the mounting surface facing the press head and pressing the molded body sheet. ..

<Other processes>
Examples of other steps include a step of leaving the molded body sheet.
The molded body sheet leaving step is not particularly limited as long as the molded body sheet can be left to stand and the surface of the molded body sheet can be covered with the exudating component exuded from the molded body sheet. , Can be appropriately selected according to the purpose.

The treatment of covering the surface of the molded body sheet with the exuding component of the binder resin exuded from the molded body sheet may be the step of leaving the molded body sheet in place of the pressing step. In this case as well, as in the pressing process, the obtained heat conductive sheet can improve the followability and adhesion to the surface of the electronic component or the heat spreader, and can reduce the thermal resistance.
The leaving time is not particularly limited and may be appropriately selected depending on the intended purpose.

The average thickness of the heat conductive sheet is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.05 mm or more and 5.00 mm or less, and more preferably 0.10 mm or more and 3.00 mm or less.

From the viewpoint of preventing short circuits of electronic circuits around the semiconductor element used, the heat conductive sheet preferably has a volume resistivity of 1.0 × 10 ¹⁰ Ω · cm or more at an applied voltage of 1,000 V. The volume resistivity is measured according to, for example, JIS K-6911.
The upper limit of the volume resistivity is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the volume resistivity may be 1.0 × 10 ¹⁸ Ω · cm or less.

From the viewpoint of adhesion to electronic components and heat sinks, the heat conductive sheet preferably has a compressibility of 3% or more at a ^{load of 0.5 kgf / cm 2, and more preferably 5% or more.}
The upper limit of the compressibility of the heat conductive sheet is not particularly limited and may be appropriately selected depending on the intended purpose, but the compressibility of the heat conductive sheet is preferably 30% or less.

(Heat dissipation structure)
The heat dissipation structure of the present invention is composed of a heating element, a heat conductive sheet, and a heat dissipation member.
The heat-dissipating structure includes, for example, a heating element such as an electronic component, a heat-dissipating member such as a heat sink, a heat pipe, and a heat spreader, and a heat conductive sheet sandwiched between the heating element and the heat-dissipating member.

The electronic component is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a CPU (Central Processing Unit), an MPU (Micro Processing Unit), and a GPU (Graphics Processing Unit).

The heat dissipation structure is not particularly limited as long as it is a structure that dissipates heat generated by an electronic component (heat generator), and can be appropriately selected according to the purpose. For example, a heat spreader, a heat sink, a vapor chamber, or a heat. Examples include pipes.
The heat spreader is a member for efficiently transferring the heat of the electronic component to other components. The material of the heat spreader is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include copper and aluminum. The heat spreader is usually in the shape of a flat plate.
The heat sink is a member for releasing the heat of the electronic component into the air. The material of the heat sink is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include copper and aluminum. The heat sink has, for example, a plurality of fins. The heat sink has, for example, a base portion and a plurality of fins provided so as to extend in a direction non-parallel (for example, in a direction orthogonal to the base portion) with respect to one surface of the base portion.
The heat spreader and the heat sink generally have a solid structure having no space inside.
The vapor chamber is a hollow structure. A volatile liquid is sealed in the internal space of the hollow structure. Examples of the vapor chamber include a heat spreader having a hollow structure, a plate-shaped hollow structure having a heat sink having a hollow structure, and the like.
The heat pipe is a hollow structure having a cylindrical shape, a substantially cylindrical shape, or a flat tubular shape. A volatile liquid is sealed in the internal space of the hollow structure.

Here, FIG. 1 is a schematic view of a semiconductor device as an example of the heat dissipation structure of the present invention. FIG. 1 is a schematic cross-sectional view of an example of a semiconductor device. The heat conductive sheet 1 of the present invention dissipates heat generated by an electronic component 3 such as a semiconductor element, and as shown in FIG. 1, is fixed to a main surface 2a facing the electronic component 3 of the heat spreader 2 and has electrons. It is sandwiched between the component 3 and the heat spreader 2. Further, the heat conductive sheet 1 is sandwiched between the heat spreader 2 and the heat sink 5. The heat conductive sheet 1 together with the heat spreader 2 constitutes a heat radiating member that dissipates heat from the electronic component 3.

The heat spreader 2 has, for example, a main surface 2a formed in a square plate shape and facing the electronic component 3, and a side wall 2b erected along the outer periphery of the main surface 2a. In the heat spreader 2, the heat conductive sheet 1 is provided on the main surface 2a surrounded by the side wall 2b, and the heat sink 5 is provided on the other surface 2c on the opposite side of the main surface 2a via the heat conductive sheet 1. The heat spreader 2 has a higher thermal conductivity, the lower the thermal resistance, and efficiently absorbs the heat of the electronic component 3 such as a semiconductor element. Therefore, the heat spreader 2 is formed by using, for example, copper or aluminum having good thermal conductivity. can do.

The electronic component 3 is, for example, a semiconductor element such as a BGA, and is mounted on the wiring board 6. Further, in the heat spreader 2, the tip surface of the side wall 2b is mounted on the wiring board 6, whereby the side wall 2b surrounds the electronic component 3 at a predetermined distance.
Then, by adhering the heat conductive sheet 1 to the main surface 2a of the heat spreader 2, a heat radiating member that absorbs the heat generated by the electronic component 3 and dissipates heat from the heat sink 5 is formed. Adhesion between the heat spreader 2 and the heat conductive sheet 1 can be performed by the adhesive force of the heat conductive sheet 1 itself.

(Electronics)
The electronic device of the present invention has the heat dissipation structure of the present invention.
An example of an electronic device is a semiconductor device using a semiconductor element as an electronic component.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

(Example 1)
-Making a heat conductive sheet-
In Example 1, aluminum hydroxide particles having a volume average particle diameter of 1 μm obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume (a treatment amount of 0.3% by volume). 44% by volume of thermally conductive particles (manufactured by Nippon Light Metal Co., Ltd.) and 21% by volume of pitch-based carbon fibers (thermally conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Nippon Graphite Fiber Co., Ltd.) are dispersed. A silicone resin composition (thermally conductive resin composition) was prepared.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume.
Next, the obtained silicone resin composition was extruded into a rectangular parallelepiped mold (50 mm × 50 mm) having a polyethylene terephthalate (PET) film peeled off on the inner wall to mold a silicone molded body.
The obtained silicone molded product was cured at 100 ° C. for 6 hours in an oven to obtain a cured silicone product. The obtained cured silicone product was cut with an ultrasonic cutter to obtain a molded sheet having a thickness of 0.43 mm. The slicing speed of the ultrasonic cutter was 50 mm per second. The ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 μm.
The obtained molded body sheet was sandwiched between peel-treated PET films, and then a spacer having a thickness of 0.4 mm was inserted and pressed to obtain a heat conductive sheet having a thickness of 0.40 mm. The pressing conditions were 87 ° C. and 0.5 MPa for 30 seconds.

(Example 2)
-Making a heat conductive sheet-
In Example 2, aluminum hydroxide particles having a volume average particle diameter of 1 μm obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume (a treatment amount of 0.3% by volume). 44% by volume of thermally conductive particles (manufactured by Nippon Light Metal Co., Ltd.) and 21% by volume of pitch-based carbon fibers (thermally conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Nippon Graphite Fiber Co., Ltd.) are dispersed. A silicone resin composition (thermally conductive resin composition) was prepared.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume.
Next, the obtained silicone resin composition was extruded into a rectangular parallelepiped mold (50 mm × 50 mm) having a polyethylene terephthalate (PET) film peeled off on the inner wall to mold a silicone molded body.
The obtained silicone molded product was cured at 100 ° C. for 6 hours in an oven to obtain a cured silicone product. The obtained cured silicone product was cut with an ultrasonic cutter to obtain a molded sheet having a thickness of 0.43 mm. The slicing speed of the ultrasonic cutter was 50 mm per second. The ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 μm.
The obtained molded body sheet was sandwiched between peel-treated PET films, and then a spacer having a thickness of 0.4 mm was inserted and pressed to obtain a heat conductive sheet having a thickness of 0.40 mm. The pressing conditions were 25 ° C. and 0.5 MPa for 30 seconds.

(Example 3)
-Making a heat conductive sheet-
In Example 3, aluminum hydroxide particles having a volume average particle diameter of 1 μm, which was obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume (a treatment amount of 0.3% by volume). 44% by volume of thermally conductive particles (manufactured by Nippon Light Metal Co., Ltd.) and 21% by volume of pitch-based carbon fibers (thermally conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Nippon Graphite Fiber Co., Ltd.) are dispersed. A silicone resin composition (thermally conductive resin composition) was prepared.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume.
Next, the obtained silicone resin composition was extruded into a rectangular parallelepiped mold (50 mm × 50 mm) having a polyethylene terephthalate (PET) film peeled off on the inner wall to mold a silicone molded body.
The obtained silicone molded product was cured at 100 ° C. for 6 hours in an oven to obtain a cured silicone product. The obtained cured silicone product was cut with an ultrasonic cutter to obtain a molded sheet having a thickness of 0.43 mm. The slicing speed of the ultrasonic cutter was 50 mm per second. The ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 μm.
The obtained molded body sheet was sandwiched between peel-treated PET films, and then a spacer having a thickness of 0.4 mm was inserted and pressed to obtain a heat conductive sheet having a thickness of 0.40 mm. The pressing conditions were 100 ° C. and 0.5 MPa for 30 seconds.

(Example 4)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 1 μm (ratio) obtained by coupling a coupling agent to 33.1% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.7% by volume. Aluminum hydroxide with a surface area of 3.3 m ² / g, thermally conductive particles: manufactured by Nippon Light Metal Co., Ltd.) and a volume average particle diameter of 1 μm obtained by coupling a coupling agent with a treatment amount of 0.2% by volume. 10% by volume of particles (heat conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and 20% by volume of pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) A heat conductive sheet of Example 4 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used after dispersion.
The two-component addition reaction type liquid silicone resin is a mixture of 19.1% by volume of silicone A solution and 14% by volume of silicone B solution. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Example 5)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 1 μm (ratio) obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.2% by volume. Aluminum hydroxide with a surface area of 3.3 m ² / g, thermally conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and a volume average particle diameter of 1 μm obtained by coupling a coupling agent with a treatment amount of 0.1% by volume. 10% by volume of particles (heat conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and 21% by volume of pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) A heat conductive sheet of Example 5 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used after dispersion.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Example 6)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 2 μm (ratio) obtained by coupling a coupling agent to 32.1% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.7% by volume. Aluminum hydroxide with a surface area of 1.4 m ² / g, thermally conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and a volume average particle diameter of 1 μm obtained by coupling a coupling agent with a treatment amount of 0.2% by volume. 10% by volume of particles (heat conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and 19% by volume of pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) A heat conductive sheet of Example 6 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used after dispersion.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 19.1% by volume and silicone B liquid in a ratio of 13% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Example 7)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 1 μm (ratio) obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume. Surface area 3.3m ² / g, heat conductive particles, manufactured by Nippon Light Metal Co., Ltd. 44% by volume, pitch carbon fiber (heat conductive fiber, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) ) 21% by volume was dispersed to obtain a heat conductive sheet of Example 7 in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Example 8)
-Making a heat conductive sheet-
In Example 1, aluminum nitride particles having a volume average particle diameter of 0.7 μm obtained by coupling a coupling agent to 32.1% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.7% by volume. (Specific surface area 2.6 m ² / g, thermally conductive particles, manufactured by Tokuyama Co., Ltd.) Hydrohydration with a volume average particle diameter of 1 μm obtained by coupling a coupling agent with a treatment amount of 38% by volume and 0.2% by volume. Aluminum particles (heat conductive particles, manufactured by Nippon Light Metal Co., Ltd.) 10% by volume and pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) 19% by volume. The heat conductive sheet of Example 8 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 19.1% by volume and silicone B liquid in a ratio of 13% by volume. The specific surface area of the aluminum nitride particles is a value measured by the BET method.

(Example 9)
-Making a heat conductive sheet-
In Example 1, aluminum nitride particles having a volume average particle diameter of 0.7 μm obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume. (Specific surface area 2.6 m ² / g, heat conductive particles, manufactured by Tokuyama Co., Ltd.) 44% by volume and pitch carbon fiber (heat conductive fiber, average fiber length 120 μm, average fiber diameter 9 μm, Japan Graphite Fiber Co., Ltd. A heat conductive sheet of Example 9 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was dispersed with 21% by volume.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum nitride particles is a value measured by the BET method.

(Example 10)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 1 μm (ratio) obtained by coupling a coupling agent to 32.1% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.7% by volume. Aluminum hydroxide with a surface area of 3.3 m ² / g, thermally conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and a volume average particle diameter of 1 μm obtained by coupling a coupling agent with a treatment amount of 0.2% by volume. Disperse 10% by volume of particles (heat conductive particles, manufactured by Nippon Light Metal Co., Ltd.) and 19% by volume of pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Japan Graphite Fiber Co., Ltd.) Then, the heat conductive sheet of Example 10 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was used.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in an amount of 18.1% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Comparative Example 1)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 3 μm (ratio) obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume. Surface area 1 m ² / g, heat conductive particles: 42% by volume (manufactured by Denki Kagaku Kogyo Co., Ltd.) and pitch-based carbon fibers (heat conductive fibers, average fiber length 120 μm, average fiber diameter 9 μm, manufactured by Nippon Graphite Fiber Co., Ltd.) A heat conductive sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that a silicone resin composition (heat conductive resin composition) was used by dispersing 23% by volume.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

(Comparative Example 2)
-Making a heat conductive sheet-
In Example 1, aluminum oxide particles having a volume average particle diameter of 1 μm (ratio) obtained by coupling a coupling agent to 34.7% by volume of a two-component addition reaction type liquid silicone resin with a treatment amount of 0.3% by volume. Surface area 1.1 m ² / g, thermally conductive particles: manufactured by Denki Kagaku Kogyo Co., Ltd. 44% by volume, pitch-based carbon fiber (thermally conductive fiber, average fiber length 120 μm, average fiber diameter 9 μm, Japan Graphite Fiber Co., Ltd. A heat conductive sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that the prepared silicone resin composition (heat conductive resin composition) was dispersed with 21% by volume.
The two-component addition reaction type liquid silicone resin is a mixture of silicone A liquid in a ratio of 20.7% by volume and silicone B liquid in a ratio of 14% by volume. The specific surface area of the aluminum oxide particles is a value measured by the BET method.

<Measurement of thermal resistance>
^{The thermal resistance (° C. cm 2} / W) of the heat conductive sheet externally processed to a diameter of 20 mm was measured with a load of ^{1 kgf / cm 2} by a method according to ASTM-D5470.

<Measurement of shore OO hardness>
For each heat conductive sheet, the shore OO hardness was measured using a shore OO hardness tester compliant with ASTM-D2240.

<Measurement of tack force>
(1) The heat conductive sheet sandwiched between the release films is pressed at 0.5 MPa for 30 seconds, and immediately after the release film is peeled off (within 3 minutes), the heat is generated at 2 mm / sec by a probe having a diameter of 5.1 mm. The tack force on the surface of the heat conductive sheet when the conductive sheet was pushed in by 50 μm and peeled off at 10 mm / sec was determined.
(2) The tack force A (gf) on the surface of the heat conductive sheet immediately after the press treatment of the above (1) is performed and the release film is peeled off, and the heat conductive sheet is pressed and then exposed to the atmosphere at a temperature of 25 ° C. After exposure for 1 hour, the tack force B (gf) on the surface of the heat conductive sheet when the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec was determined by the following equation. , (B / A) × 100 was obtained (retention rate of tack force after air exposure).
(3) Immediately after slicing the heat conductive sheet (within 5 minutes), the heat conduction sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec. The tack force on the sheet surface was calculated.
Here, the tack force in the above (1) to (3) is a value measured in the DEPTH mode using a tackine tester manufactured by Malcolm Co., Ltd. That is, it is the tack force on the surface of the heat conductive sheet when the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec.

<Evaluation of tackiness based on handling at the time of mounting>
Each heat conductive sheet was placed on an aluminum (Al) plate, and the holding time until the heat conductive sheet fell from the Al plate when inverted without applying pressure was measured and evaluated according to the following criteria.
[Evaluation criteria]
〇: Holds for 300 seconds or more ×: Drops in less than 300 seconds

1 Heat conduction sheet 2 Heat dissipation member (heat spreader)
2a Main surface 3 Heating element (electronic component)
3a Top surface 5 Heat dissipation member (heat sink)
6 Wiring board

Claims (12)

A heat conductive sheet made of a cured product of a resin composition containing carbon fibers, an inorganic filler other than the carbon fibers, and a binder resin.
A heat conductive sheet characterized by satisfying the following (1) and (2).
(1) The heat conductive sheet sandwiched between the release films is pressed at 0.5 MPa for 30 seconds, and immediately after the release film is peeled off, the heat conductive sheet is pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm. The tack force on the surface of the heat conductive sheet when peeled off at 10 mm / sec is 100 gf or more.
(2) The tack force A (gf) on the surface of the heat conductive sheet immediately after the press treatment of the above (1) was performed and the release film was peeled off, and the heat conductive sheet was pressed and then exposed to the atmosphere for 1 hour. Later, the tack force B (gf) on the surface of the heat conductive sheet when the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec was calculated by the following equation (B /). A) × 100 ≧ 80%. Further, (3) immediately after slicing the heat conductive sheet, the heat conductive sheet was pushed in by 50 μm at 2 mm / sec with a probe having a diameter of 5.1 mm and peeled off at 10 mm / sec on the surface of the heat conductive sheet. The heat conductive sheet according to claim 1, wherein the tack force is 20 gf or less. The heat conductive sheet according to any one of claims 1 to 2, wherein the heat conductive sheet has a shore OO hardness of 40 or more and 70 or less. Wherein the inorganic filler other than carbon fiber has a specific surface area of at least 1.4 m 2 / ^g or more aluminum oxide or a specific surface area of 1.4 m 2 / ^g or more aluminum nitride, and any one of aluminum hydroxide, wherein Item 6. The heat conductive sheet according to any one of Items 1 to 3. The heat conductive sheet according to any one of claims 1 to 4, wherein the inorganic filler other than carbon fiber contains either aluminum oxide or aluminum nitride and aluminum hydroxide. The heat conductive sheet according to any one of claims 4 to 5, wherein the specific surface area of either the aluminum oxide or the aluminum nitride is 1.4 m ² / g or more and 3.3 m ^{2 / g or less.} The heat conductive sheet according to any one of claims 1 to 6, wherein the volume average particle diameter of the inorganic filler other than carbon fiber is 0.4 μm or more and 2 μm or less. The heat conductive sheet according to claim 7, wherein the volume average particle diameter of the inorganic filler other than carbon fibers is 0.7 μm or more and 2 μm or less. The heat conductive sheet according to any one of claims 1 to 8, wherein the binder resin is a silicone resin. The method for manufacturing the heat conductive sheet according to any one of claims 1 to 9.
A molding body manufacturing step of obtaining a molded body of the resin composition by molding a resin composition containing a binder resin, carbon fibers, and an inorganic filler other than the carbon fibers into a predetermined shape and curing the resin composition.
The step of producing a molded body sheet by cutting the molded body into a sheet to obtain a molded body sheet, and
A method for producing a heat conductive sheet, which comprises. A heat radiating structure comprising a heating element, the heat conductive sheet according to any one of claims 1 to 9, and a heat radiating member in this order. An electronic device having the heat dissipation structure according to claim 11.

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