TW202231765A - Heat-conductive sheet, method for installing same, and method for manufacturing same - Google Patents

Abstract

The heat-conductive sheet according to the present invention comprises a binder component which is a mixture of a silicone matrix (A) and a hydrocarbon-based compound (B), and a heat conductive filler (C) dispersed in the binder component. The heat conductive filler (C) includes an anisotropic filler aligned in the thickness direction. The heat-conductive sheet has a thickness of 0.05-0.5 mm. According to the present invention, it is possible to provide a heat-conductive sheet that enables reduction in the thermal resistance value thereof even when the thickness is small and the heat-conductive sheet is compressed with a small load.

Description

Thermally conductive sheet, method for assembling the same, and method for manufacturing the same

The present invention relates to a thermally conductive sheet, for example, to a thermally conductive sheet used between a heat generating body and a heat sink.

In electronic devices such as computers, automobile parts, and mobile phones, heat sinks such as radiators are generally used in order to dissipate heat generated by heat-generating bodies such as semiconductor elements and mechanical parts. In order to improve the efficiency of heat transfer to the heat sink, it is known to arrange a thermally conductive sheet between the heat generating body and the heat sink.

In order to further improve the conduction efficiency, the thermally conductive sheet is required to have followability to the heat generating body and the heat sink. Therefore, a phase-change type thermally conductive sheet called a so-called phase-change sheet, which is softened or melted by heating, has been studied. For example, Patent Document 1 discloses a heat sink that contains at least an alkyl group-introduced silicone oil, α-olefin, and a thermally conductive filler, is in a putty form at normal temperature, and is softened and fluidized by heating.

Moreover, as a thermally conductive sheet, a thermally conductive sheet using a polymer gel is also known. For example, Patent Document 2 discloses a thermally softening heat sink comprising a composition comprising a polymer gel, which is solid or paste-like at room temperature, and is characterized by being softened by heating. It becomes a liquid compound and a thermally conductive filler. In addition, Patent Document 3 discloses a thermally conductive sheet comprising a thermally conductive resin layer containing a binder resin containing wax and a thermally conductive filler dispersed in the binder resin, and using Silicone gel as binder resin. The phase change sheet disclosed in each of the above Patent Documents 1 to 3 and the thermally conductive sheet using a polymer gel such as polysiloxane gel have high flexibility, and therefore have good followability to a heat sink and a heat generating body. Can improve thermal conductivity. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2004-331835 Patent Document 2: Japanese Patent Laid-Open No. 2002-234952 Patent Document 3: Japanese Patent Laid-Open No. 2001-291807

[The problem to be solved by the invention]

However, it is known that when the thickness of the conventional thermally conductive sheet as described above is thin, if the load at the time of assembly is low due to compression between the heat generating body and the heat sink at a high temperature, there is a problem with the heat generating body and the heat sink. The followability of the heat sink becomes poor, resulting in a problem that the thermal resistance value increases (the thermal conductivity decreases). On the other hand, when the thermally conductive sheet is compressed with a high load, the thermal resistance value decreases, but the load on the heating element and the heat sink increases, so a thermal conductivity with a low thermal resistance value even under a low load condition is required sex film.

Therefore, an object of the present invention is to provide a thermally conductive sheet which has a thin thickness and can reduce thermal resistance even when compressed under a low load. [Technical means to solve the problem]

The inventors of the present invention have conducted active research, and as a result, have found that the following problems can be solved by a thermally conductive sheet comprising: a binder component comprising a polysiloxane (A) and a hydrocarbon-based A mixture of the compound (B); and a thermally conductive filler (C) dispersed in the above-mentioned adhesive component; the above-mentioned thermally conductive filler (C) contains an anisotropic filler oriented in the thickness direction; and the thermally conductive sheet The thickness is 0.05 ~ 0.5 mm. That is, the present invention provides the following [1] to [11].

[1] A thermally conductive sheet comprising: a binder component which is a mixture of a polysiloxane (A) and a hydrocarbon-based compound (B); and a thermally conductive filler (C) dispersed in the binder component In; the thermally conductive filler (C) contains anisotropic fillers oriented along the thickness direction; and the thermally conductive sheet has a thickness of 0.05 to 0.5 mm. [2] The thermally conductive sheet according to [1], wherein the thermal resistance value R ₄₀ (°C·in ² /W) measured at 80° C. under a load of 40 psi and the measured thickness T ₄₀ (mm), And the slope α represented by the following formula (1) calculated from the thermal resistance value R ₁₀ (°C·in ² /W) measured at 80°C and a load of 10 psi and the thickness T ₁₀ (mm) at the time of measurement is 0.4 or less. α=(R ₄₀ -R ₁₀ )/(T ₄₀ -T ₁₀ )...(1) [3] The thermally conductive sheet according to the above [1] or [2], wherein the hydrocarbon-based compound (B ) has a melting point higher than 23°C and below 80°C. [4] The thermally conductive sheet according to any one of the above [1] to [3], wherein the hydrocarbon-based compound (B) is a crystalline polyα-olefin. [5] The thermally conductive sheet according to any one of the above [1] to [4], wherein the content of the hydrocarbon-based compound (B) is relative to the polysiloxane material (A) and the hydrocarbon-based compound (B) The total of 100 parts by mass is 0.5 to 15 parts by mass. [6] The thermally conductive sheet according to any one of the above [1] to [5], wherein the thermally conductive filler (C) has a volume filling rate of 30 to 85% by volume. [7] A heat dissipating member comprising the thermally conductive sheet according to any one of the above [1] to [6] and a heat sink, wherein the thermally conductive sheet is attached to a surface of the heat sink. [8] A method of assembling a thermally conductive sheet, comprising the steps of: disposing a thermally conductive sheet on the surface of a first member, the thermally conductive sheet having an adhesive component and a thermally conductive filler (C), and the adhesive The agent component is a mixture of polysiloxane (A) and hydrocarbon compound (B), the thermally conductive filler (C) is dispersed in the above-mentioned adhesive component; the above-mentioned thermally conductive filler (C) contains a anisotropic filler; and the thickness of the thermally conductive sheet is 0.05 to 0.5 mm; the step of heating the thermally conductive sheet; and the second member is disposed on the opposite side of the thermally conductive sheet to the surface on the side of the first member A step of attaching the above-mentioned thermally conductive sheet between the above-mentioned first and second members by pressing the above-mentioned thermally conductive sheet on the surface. [9] The method for assembling a thermally conductive sheet according to the above [8], wherein the hydrocarbon-based compound (B) has a melting point higher than 23° C., and the thermally conductive sheet is heated to a temperature equal to or higher than the melting point. [10] A method of manufacturing a thermally conductive sheet, comprising the steps of: combining at least a curable polysiloxane composition (A1), a hydrocarbon-based compound (B), and a thermally conductive filler (C) containing an anisotropic filler ), and the compatible substance (D) are mixed to obtain a mixed composition; and a step of hardening the above mixed composition by heating. [11] The method for producing a thermally conductive sheet according to the above [10], wherein the compatible substance (D) is an alkoxysilane compound. [Effect of invention]

According to the present invention, it is possible to provide a thermally conductive sheet which has a thin thickness and can reduce thermal resistance even when it is compressed with a low load when mounted on a heat generating body, a heat sink, or the like.

[Thermal Conductive Sheet] Hereinafter, the thermally conductive sheet according to the embodiment of the present invention will be described in detail. The thermally conductive sheet of the present invention includes: a binder component, which is a mixture of a polysiloxane material (A) and a hydrocarbon compound (B); and a thermally conductive filler (C) dispersed in the binder component; the above-mentioned thermally conductive filler The material (C) contains anisotropic fillers aligned along the thickness direction; and the thickness of the thermally conductive sheet is 0.05 to 0.5 mm.

The thermally conductive sheet of the present invention, having the above-mentioned constitution, ensures a certain degree of flexibility when heated at a high temperature (ie, when used), and can ensure followability without applying a high load to a heating element, a heat sink, etc. even if the thickness is thin , and the thermal conductivity becomes good.

Although the thickness of the thermally conductive sheet is thin, the principle of good followability to the heat generating body, the heat sink, etc. under a low load is uncertain, but it can be estimated as follows. The thermally conductive sheet of the present invention contains the hydrocarbon-based compound (B) as a binder component. The hydrocarbon-based compound (B) is softened, melted, and reduced in viscosity during heating, thereby improving the flexibility of the thermally conductive sheet, thereby improving the followability to a heat generating body and a heat sink. In addition, the thermally conductive sheet of the present invention contains, as the thermally conductive filler (C), an anisotropic filler oriented in the thickness direction of the sheet. Thereby, the heat conduction channel in the thickness direction of the sheet is easily formed. Based on these factors, the thermal conductivity of the thermally conductive sheet is considered to be improved.

Furthermore, it is presumed that the hydrocarbon compound (B) and the polysiloxane (A) are incompatible, so in the adhesive component, the polysiloxane (A) is the sea component and the hydrocarbon compound (B) is the island component. island structure. By making the adhesive component have a sea-island structure, even if the hydrocarbon-based compound (B) is softened, melted, and reduced in viscosity during heating, it will continue to be maintained by the polysiloxane (A), and the flexibility is improved. Pump out can be suppressed. In addition, since the polysiloxane material (A) constitutes the sea component, the thermally conductive sheet has a specific resilience, so that it can be stably mounted between heat generating bodies or heat sinks without generating an air layer therebetween.

＜Thickness＞ The thickness of the thermally conductive sheet of the present invention is 0.05 to 0.5 mm. If the thickness of the thermally conductive sheet is less than 0.05 mm, the followability of the thermally conductive sheet to the heat generating body or the heat sink tends to be poor, and the thermal resistance value tends to be high. On the other hand, when the thickness of the thermally conductive sheet exceeds 0.5 mm, it is difficult to use for small electronic equipment and the like. The thickness of the thermally conductive sheet is preferably 0.08 to 0.5 mm, more preferably 0.1 to 0.4 mm. The thermally conductive sheet of the present invention has a relatively thin thickness as described above, but as described above, the thermal resistance value can be reduced even under a low load when mounted between the heat generating body and the heat sink.

<Slope α> The thermally conductive sheet of the present invention is preferably based on the thermal resistance value R ₄₀ measured at 80° C. under a load of 40 psi (0.276 MPa) and the thickness T ₄₀ at the time of measurement, and at a load of 10 psi (0.069 MPa) The slope α represented by the following formula (1) calculated from the measured thermal resistance value R ₁₀ and the measured thickness T ₁₀ was 0.4 or less. α=(R ₄₀ -R ₁₀ )/(T ₄₀ -T ₁₀ )...(1) By setting the slope α to be 0.40 or less, the followability to the heating element, the radiator, etc. can be achieved even under a low load A thermally conductive sheet that is still good and has excellent thermal conductivity. The slope α is preferably 0.3 or less, more preferably 0.2 or less, and still more preferably 0.1 or less. Furthermore, the units of thermal resistance values R ₄₀ and R ₁₀ are °C·in ² /W, and the units of thicknesses T ₄₀ and T ₁₀ are mm. In general, the thermal resistance of thermally conductive sheets measured at a relatively high load of 40 psi is lower than when measured at a relatively low load of 10 psi. Therefore, with respect to the slope α represented by the formula (1), which expresses the change of the thermal resistance value with respect to the change of the thickness, as the value decreases and gradually approaches zero, it means that even at a low load, it can show a The same and similar thermal resistance value at high load. Therefore, by adjusting the slope α to be small, a thermally conductive sheet having a low thermal resistance value even under a low load can be obtained. The inclination α can be adjusted by the blending amount of the hydrocarbon compound (B) or the thermally conductive filler (C), the manufacturing method of the following thermally conductive sheet, and the like. The thermal resistance value R ₄₀ measured at a load of 40 psi and the thermal resistance value R ₁₀ measured at a load of 10 psi can be measured by the methods described in the examples.

<Compression ratio> The thermally conductive sheet of the present invention preferably has a compression ratio of 15% or more at 40 psi. When the compression ratio of the thermally conductive sheet is 15% or more, the flexibility during heating is high, the followability to the heating element or the radiating element during use is improved, and the thermal conductivity is improved. From the viewpoint of improving flexibility during use and improving thermal conductivity, the above-mentioned compression ratio is preferably 18% or more, more preferably 20% or more. In addition, the above-mentioned compression ratio is preferably 50% or less. By setting the compression ratio to be 50% or less, it is easy to improve the operability and reliability, and it is easy to install it in an electronic device or a cutting process, and furthermore, it is difficult to generate pumping or the like. From these viewpoints, the above-mentioned compression ratio is more preferably 40% or less, and still more preferably 38% or less. The compression ratio was measured by the method described in the Example.

＜Polysiloxane (A)＞ The polysiloxane material (A) may be polysiloxane that has no fluidity at room temperature (23°C) and high temperature (80°C). Since the polysiloxane material (A) has no fluidity, the shape retention of the thermally conductive sheet can be ensured at normal temperature and high temperature. In addition, as the polysiloxane material (A) of the present invention, for example, polysiloxane rubber can be used. By using polysiloxane rubber, the thermal conductive sheet becomes easy to be compressed and deformed, and it is easy to be installed between the heat generating body and the heat sink. Moreover, since a certain compression characteristic can be imparted to the thermally conductive sheet, reliability can be improved.

The polysiloxane used as the polysiloxane material (A) can be either a condensation reaction type or an addition reaction type, so that it is easy to fill the thermal conductive filler to a high degree, and the curing temperature can be easily adjusted by a catalyst or the like. On the other hand, an addition reaction type is preferable. The polysiloxane material (A) can be obtained, for example, by curing the curable polysiloxane composition (A1). The curable polysiloxane composition (A1) may be composed of, for example, a main agent and a curing agent.

When the curable polysiloxane composition (A1) is an addition reaction type, from the viewpoint of easily filling a thermally conductive filler to a high degree, it is preferably an alkenyl group-containing organic polymer as a main ingredient. Siloxane, and hydrogen organopolysiloxan as a hardener. In addition, the curable polysiloxane composition (A1) is preferably in a liquid state before curing. By making the curable polysiloxane composition (A1) liquid before curing, it is easy to fill the thermal conductive filler to a high degree, and further, it is easy to disperse the hydrocarbon-based compound (B) in the curable polysiloxane composition (A1) )middle. In addition, in this specification, a liquid state means that it is a liquid under normal temperature (23 degreeC) and 1 atmosphere.

Moreover, in order to ensure the shape retention property of a thermally conductive sheet, it is preferable to use a three-dimensionally crosslinked polysiloxane material as the polysiloxane material (A). Therefore, for example, in the case of an addition reaction type, the curable polysiloxane composition (A1) may be cured, and the curable polysiloxane composition (A1) contains at least 3 or more alkenyl groups in one molecule. The alkenyl-containing organopolysiloxane, or the hydrogenated organopolysiloxane having at least 3 or more hydrogen added to the silicon atom.

The content of the polysiloxane material (A) may be, for example, about 15 to 70% by mass, preferably 17 to 50% by mass, and more preferably 20 to 39% by mass, based on the total amount of the thermally conductive sheet.

<Hydrocarbon-based compound (B)> The hydrocarbon-based compound (B) used in the present invention may be a liquid at room temperature or a compound that is melted by heating to a certain temperature (for example, a temperature higher than 23°C and 80°C or lower). When the thermally conductive sheet contains a liquid or a compound melted by heating as the hydrocarbon-based compound (B), the flexibility can be improved when heated at high temperature, the above-mentioned slope α can be easily reduced, and the compressibility can be easily improved.

The melting point of the hydrocarbon-based compound (B) is preferably 80°C or lower, more preferably 70°C or lower, still more preferably 60°C or lower, still more preferably 60°C or lower, from the viewpoint of being meltable when heated at high temperature (for example, 80°C). Below 50℃. The hydrocarbon-based compound (B) is preferably in a solid state at room temperature and 1 atm. By making it solid at room temperature, workability can be improved. For example, when the following cutting process is performed at a temperature close to room temperature, a thermally conductive sheet can be easily obtained by making it have specific rigidity. Therefore, the melting point of the hydrocarbon-based compound is preferably higher than normal temperature (23°C), more preferably 30°C or higher, and still more preferably 35°C or higher. The melting point of the hydrocarbon-based compound is the temperature of the endothermic peak of the DTA curve measured at a heating rate of 1°C/min using thermogravimetric differential thermal analysis (TGDTA). In addition, when the hydrocarbon-based compound is a mixture, the melting point is the largest endothermic peak in the above-mentioned temperature range.

Specific examples of the hydrocarbon-based compound include liquid paraffin, paraffin wax, petrolatum, polyα-olefin (PAO), polyethylene wax, polypropylene wax, and the like. Among them, paraffin wax, petrolatum, poly-α-olefin (PAO), polyethylene wax, and polypropylene wax are preferable from the viewpoint of workability at room temperature and the like. In addition, vaseline is a semi-solid hydrocarbon compound, and is a mixture of plural hydrocarbon compounds such as isoparaffin, cycloparaffin (cycloparaffin), and naphthene (naphthene). Moreover, as a petrolatum, the white petrolatum defined by Japanese Pharmacopoeia can be illustrated, for example.

Among the above, poly-α-olefin (PAO) is preferred, and among them, crystalline poly-α-olefin (CPAO) having crystallinity is more preferred. Polyalpha-olefins are polymers of alpha-olefins. The kind of α-olefin is not particularly limited, and may be linear, branched, or cyclic. The polyα-olefin is, for example, a polymer of an α-olefin having 2 to 30 carbon atoms, preferably 6 to 20 carbon atoms. The crystalline poly-alpha-olefin can, for example, increase the carbon number of the alpha-olefin to form a side-chain crystalline poly-alpha-olefin. The polyα-olefin can be a polymer of a single α-olefin or a copolymer of two or more α-olefins.

In the thermally conductive sheet, the content of the hydrocarbon-based compound (B) is preferably 0.5 to 15 parts by mass relative to 100 parts by mass in total of the polysiloxane material (A) and the hydrocarbon-based compound (B). When the content of the hydrocarbon-based compound (B) is 0.5 parts by mass or more, the thermally conductive sheet has a certain flexibility at high temperature, and the thermal conductivity when mounted between a heat generating body and a heat sink or the like becomes easy to improve. On the other hand, when the said content is 15 mass parts or less, a certain amount of polysiloxane substance (A) is contained in a thermally conductive sheet, and the shape retention property of a thermally conductive sheet can be made favorable. Furthermore, the thermally conductive sheet tends to have moderate resilience, and can be stably mounted between the heating bodies or the radiating bodies without generating an air layer, and the reliability can be improved. From these viewpoints, the content of the hydrocarbon-based compound (B) is more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, and more preferably 40 parts by mass or less , more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less.

In addition, the polysiloxane material (A) is formed of the following curable polysiloxane composition (A1). Therefore, in the following mixed composition, with respect to 100 parts by mass of the total of the curable polysiloxane composition (A1) and the hydrocarbon-based compound (B), the content of the hydrocarbon compound (B) is the same as that of the above-mentioned hydrocarbon compound (B). The content is the same. The content of the following thermally conductive filler (C), anisotropic filler, and non-anisotropic filler is also the same. In addition, the adhesive component may be composed of the polysiloxane (A) and the hydrocarbon compound (B), and resin components other than the polysiloxane (A) may be contained within a range that does not impair the effects of the present invention. , or a plasticizer other than the hydrocarbon compound (B) as an adhesive component.

<Thermally conductive filler (C)> The thermally conductive sheet of the present invention further includes a thermally conductive filler (C). The thermally conductive filler (C) may be dispersed in the binder component which is a mixture of the polysiloxane (A) and the hydrocarbon compound (B), and may be held in the binder component. The thermally conductive filler contains anisotropic fillers oriented along the thickness direction of the thermally conductive sheet. Thereby, it becomes easy to improve thermal conductivity of a thermally conductive sheet. When aligning in the thickness direction, it becomes difficult to increase the compressibility in the thickness direction, but in the present invention, the compressibility in the thickness direction can be improved by dispersing the hydrocarbon-based compound (B) in the polysiloxane (A). Furthermore, when the anisotropic filler is aligned along the thickness direction, its long axis direction does not need to be strictly parallel to the thickness direction, even if the long axis direction is slightly inclined with respect to the thickness direction, it is considered to be aligned along the thickness direction. Specifically, if the long axis direction is not inclined by about 20°, it is still regarded as an anisotropic filler oriented along the thickness direction. If the total number of tropic fillers exceeds 60%, preferably more than 80%), it is regarded as oriented along the thickness direction.

The content of the thermally conductive filler (C) is preferably 150 to 3000 parts by mass, more preferably 200 to 2000 parts by mass, with respect to 100 parts by mass in total of the polysiloxane material (A) and the hydrocarbon compound (B), and further Preferably it is 300-1000 mass parts. By setting the thermally conductive filler (C) to be 150 parts by mass or more, a certain thermal conductivity can be imparted to the thermally conductive sheet. Moreover, by setting it as 1500 mass parts or less, a thermally conductive filler (C) can be suitably dispersed in a binder component. In addition, the viscosity of the following mixed composition can be prevented from increasing more than necessary. In addition, the volume filling rate of the thermally conductive filler with respect to the total amount of the thermally conductive sheet is preferably 30 to 85% by volume, more preferably 50 to 83% by volume, and still more preferably 61 to 80% by volume. By setting the volume filling rate to be equal to or more than the above lower limit value, a certain thermal conductivity can be imparted to the thermally conductive sheet. Moreover, it becomes easy to manufacture a thermally conductive sheet by setting it as the upper limit or less.

(Anisotropic filler) Anisotropic fillers are fillers with anisotropy in shape and can be aligned. As anisotropic filler, a fiber material, a scaly material, etc. are mentioned. The anisotropic filler is one having a high aspect ratio, specifically, one having an aspect ratio exceeding 2, and the aspect ratio is preferably 5 or more. When the aspect ratio is larger than 2, it becomes easy to align the anisotropic filler in a single direction such as the thickness direction, and it becomes easy to improve the thermal conductivity in a single direction such as the thickness direction of the thermally conductive sheet. In addition, the upper limit of the aspect ratio is not particularly limited, but the upper limit is 100 in terms of practicality. Furthermore, the aspect ratio refers to the ratio of the length of the anisotropic filler in the long-axis direction to the length in the short-axis direction. The length/thickness of the long axis of the scaly material.

The content of the anisotropic filler in the thermally conductive sheet is preferably 10 to 500 parts by mass, more preferably 30 to 300 parts by mass relative to 100 parts by mass in total of the polysiloxane material (A) and the hydrocarbon compound (B). parts, more preferably 50 to 250 parts by mass. It becomes easy to improve thermal conductivity by making content of an anisotropic filler 10 mass parts or more. Moreover, by setting it as 500 mass parts or less, the viscosity of the following mixed composition becomes a suitable viscosity easily, and the orientation of an anisotropic filler becomes favorable. Furthermore, the dispersibility of the anisotropic filler in the polysiloxane material (A) also becomes favorable.

When the anisotropic filler is a fiber material, the average fiber length is preferably 10-500 μm, more preferably 20-350 μm, and still more preferably 50-300 μm. When the average fiber length is set to 10 μm or more, the anisotropic fillers are properly brought into contact with each other inside the thermally conductive sheet, so that a heat transfer path is secured, and the thermal conductivity of the thermally conductive sheet becomes good. On the other hand, when the average fiber length is set to 500 μm or less, the volume of the anisotropic filler becomes small, and the binder component can be filled to a high degree. Further, the average fiber length of the fiber material is preferably shorter than the thickness of the thermally conductive sheet. By being shorter than the thickness, the fiber material is prevented from protruding more than necessary from the surface of the thermally conductive sheet. In addition, the above-mentioned average fiber length can be calculated by observing the anisotropic filler under a microscope. More specifically, the fiber length of 50 arbitrary anisotropic fillers can be measured, for example, using an electron microscope or an optical microscope, and the average value (arithmetic average value) can be set as the average fiber length.

In addition, when the anisotropic filler is a scaly material, the average particle size is preferably 10 to 400 μm, more preferably 15 to 300 μm, and still more preferably 20 to 200 μm. By setting the average particle diameter to be 10 μm or more, in the thermally conductive sheet, the anisotropic fillers are easily brought into contact with each other, the heat transfer path is secured, and the thermal conductivity of the thermally conductive sheet becomes good. On the other hand, when the average particle diameter is 400 μm or less, the volume of the thermally conductive sheet becomes small, and it becomes possible to fill the adhesive component with anisotropic filler to a high degree. In addition, the average particle diameter of the scaly material can be calculated by observing the anisotropic filler with a microscope and using the long axis as the diameter. More specifically, the long diameter of 50 arbitrary anisotropic fillers can be measured using, for example, an electron microscope or an optical microscope, and the average value (arithmetic average value) can be set as the average particle size.

唑纖維等。其中，碳系材料由於比重較小，於黏合劑成分中之分散性良好，故較佳，其中更佳為導熱率較高之石墨化碳材料。石墨化碳材料藉由石墨面排列於特定方向上而具備反磁性。 又，作為異向性填充材，氮化硼亦較佳。氮化硼並未特別限定，較佳為以鱗片狀材料之形式使用。鱗片狀氮化硼可經凝集，亦可未凝集，較佳為一部分或全部未凝集。再者，氮化硼等亦藉由結晶面排列於特定方向上而具備反磁性。 As the anisotropic filler, a known material having thermal conductivity can be used, and in the case of aligning by magnetic field alignment as described below, it is sufficient to have diamagnetism. On the other hand, when the alignment is performed by flow alignment, or when the anisotropic filler is not aligned, it may not have diamagnetism. Specific examples of the anisotropic filler include: carbon-based materials represented by carbon fibers or scaly carbon powder; metal materials or metal oxides represented by metal fibers; boron nitride or metal nitride; metal Carbide; Metal Hydroxide; Polyparaphenylene Benzo

azole fibers, etc. Among them, carbon-based materials are preferred because of their relatively small specific gravity and good dispersibility in the binder component, and more preferred are graphitized carbon materials with higher thermal conductivity. The graphitized carbon material is diamagnetic by arranging the graphite planes in a specific direction. Moreover, boron nitride is also preferable as an anisotropic filler. The boron nitride is not particularly limited, and it is preferably used in the form of a scaly material. The scaly boron nitride may or may not be agglomerated, preferably a part or all of it is not agglomerated. Furthermore, boron nitride or the like is also diamagnetic by arranging crystal planes in a specific direction.

In addition, the anisotropic filler is not particularly limited, and the thermal conductivity along the direction with anisotropy (ie, the long axis direction) is generally 30 W/m·K or more, preferably 60 W/m·K or more , more preferably 100 W/m·K or more, still more preferably 200 W/m·K or more. The upper limit of the thermal conductivity of the anisotropic filler is not particularly limited, but is, for example, 2000 W/m·K or less. Thermal conductivity can be measured by a laser flash method or the like.

Anisotropic fillers may be used alone or in combination of two or more. For example, as the anisotropic filler, at least two types of anisotropic fillers having mutually different average particle diameters or average fiber lengths can be used. It is considered that if anisotropic fillers of different sizes are used, the anisotropic fillers can be filled in the adhesive with a high density by allowing the smaller anisotropic fillers to enter between the relatively large anisotropic fillers In the composition of the agent, and improve the heat conduction efficiency.

The carbon fibers used as anisotropic fillers are preferably graphitized carbon fibers. Moreover, as a flaky carbon powder, a flaky graphite powder is preferable. As anisotropic fillers, it is also preferable to use graphitized carbon fibers and flake graphite powder together. Regarding the graphitized carbon fiber, the crystal planes of graphite are connected in the fiber axis direction, and the fiber axis direction has high thermal conductivity. Therefore, by aligning the fiber axis direction in a specific direction, the thermal conductivity in the specific direction can be improved. In addition, regarding the flake-like graphite powder, the crystal planes of graphite are connected in the in-plane direction of the flake surfaces, and the in-plane direction thereof has high thermal conductivity. Therefore, by arranging the scale surfaces in a specific direction, the thermal conductivity in a specific direction can be improved. The graphitized carbon fiber and flake graphite powder are preferably those with a high degree of graphitization.

As the graphitized carbon materials such as the above-mentioned graphitized carbon fibers and scaly graphite powders, those obtained by graphitizing the following raw materials can be used. For example, condensed polycyclic hydrocarbon compounds such as naphthalene, PAN (polyacrylonitrile), condensed heterocyclic compounds such as pitch, etc., are preferably used graphitized mesophase pitch with high degree of graphitization, polyimide, polybenzyl indoles. For example, by using a mesophase pitch, the pitch is aligned in the fiber axis direction due to its anisotropy in the spinning step described below, and a graphitized carbon fiber having excellent thermal conductivity in the fiber axis direction can be obtained. The usage of the mesophase pitch in the graphitized carbon fiber is not particularly limited as long as spinning is possible, and the mesophase pitch may be used alone or in combination with other raw materials. Among them, in terms of high thermal conductivity, spinnability, and quality stability, it is best to use mesophase pitch alone, that is, graphitized carbon fibers with a mesophase pitch content of 100%.

Regarding the graphitized carbon fiber, the processes of spinning, non-melting and carbonization can be used in sequence, and those obtained by pulverizing or cutting into a specific particle size and then graphitizing; or after carbonizing, pulverizing or cutting and then graphitizing gainer. In the case of pulverization or cutting before graphitization, polycondensation reaction and cyclization reaction are easily carried out during the graphitization treatment of the surface newly exposed on the surface due to pulverization, so the degree of graphitization can be increased, and the thermal conductivity can be further improved. Graphitized carbon fiber. On the other hand, when the spun carbon fiber is graphitized and then pulverized, the graphitized carbon fiber is rigid, so it is easy to pulverize, and a carbon fiber powder with a relatively narrow fiber length distribution can be obtained in a short time of pulverization.

As described above, the average fiber length of the graphitized carbon fibers is preferably 10 to 500 μm, more preferably 20 to 350 μm, and still more preferably 50 to 300 μm. In addition, the aspect ratio of the graphitized carbon fiber is more than 2, preferably 5 or more, as described above. The thermal conductivity of the graphitized carbon fiber is not particularly limited, and the thermal conductivity in the fiber axis direction is preferably 400 W/m·K or more, more preferably 800 W/m·K or more.

When the thermally conductive sheet contains an anisotropic filler, the anisotropic filler may or may not be exposed on the surface of the sheet, but is preferably exposed. By exposing the anisotropic filler, the sheet surface of the thermally conductive sheet can be a non-adhesive surface. The thermally conductive sheet is the main surface of the sheet, the anisotropic filler can be exposed only on either side of the two surfaces of the sheet, and the anisotropic filler can also be exposed on both sides. Since the thermally conductive sheet is non-adhesive on the surface of the sheet, the thermally conductive sheet can be slid or the like when mounted on an electronic device, etc., thereby improving the mountability.

(Non-Anisotropic Filler) The thermally conductive filler (C) in the present invention further contains a non-anisotropic filler, and the above-mentioned anisotropic filler and non-anisotropic filler can be used in combination. In particular, the non-anisotropic filler is used in combination with the anisotropic filler oriented in a single direction, and the gap between the oriented anisotropic fillers can further improve the thermal conductivity. Non-anisotropic fillers are fillers that are not substantially anisotropic in shape. The fillers are produced by the following magnetic lines of force or under the action of shear force, etc., even if the anisotropic fillers are aligned in a specific direction. Under normal circumstances, the filler material will not be aligned in that particular direction.

The aspect ratio of the non-anisotropic filler is 2 or less, preferably 1.5 or less. When such a non-anisotropic filler with a low aspect ratio is used in combination with an anisotropic filler, it is easy to arrange in the gap between the anisotropic fillers, and it is easy to improve the thermal conductivity. In addition, by setting the aspect ratio to be 2 or less, the viscosity of the following mixed composition can be prevented from rising, and it can be filled to a high degree.

Specific examples of the non-isotropic filler include metals, metal oxides, metal nitrides, metal hydroxides, carbon materials, oxides other than metals, nitrides, carbides, and the like. In addition, the shape of the non-anisotropic filler may, for example, be spherical, amorphous powder or the like. In the non-anisotropic filler, as the metal, aluminum, copper, nickel, etc. can be exemplified; As the nitride, aluminum nitride, etc. may be mentioned. As the metal hydroxide, aluminum hydroxide may, for example, be mentioned. Furthermore, as a carbon material, spherical graphite etc. are mentioned. As oxides, nitrides, and carbides other than metals, quartz, boron nitride, silicon carbide, and the like may, for example, be mentioned. Among them, alumina or aluminum is preferable in that the thermal conductivity is high and spherical shape is easily obtained. The non-anisotropic filler may be used alone or in combination of two or more.

The average particle size of the non-isotropic filler is, for example, 0.1 to 200 μm. For example, when used together with an anisotropic filler, the average particle size of the non-anisotropic filler is preferably 0.1 to 50 μm, more preferably 0.5 to 35 μm, and still more preferably 1 to 15 μm. By setting the average particle diameter to be 50 μm or less, even if it is used in combination with an anisotropic filler, abnormalities such as disturbing the orientation of the anisotropic filler are less likely to occur. In addition, by setting the average particle diameter to be 0.1 μm or more, the specific surface area of the non-anisotropic filler does not become larger than necessary, and even if a large amount is blended, the viscosity of the mixed composition is not easily increased, and the viscosity of the mixed composition is easily increased. Filled with non-isotropic filler material. As the non-anisotropic filler, for example, non-anisotropic fillers having at least two types of mutually different average particle diameters can be used as the non-anisotropic filler.

Moreover, the average particle diameter of the non-anisotropic filler is preferably 0.1 to 200 μm, more preferably 0.5 to 100 μm, and still more preferably 1 to 70 μm. In addition, the average particle diameter of the non-anisotropic filler can be measured by observation with an electron microscope or the like. More specifically, the particle size of 50 arbitrary non-isotropic fillers can be measured, for example, using an electron microscope or an optical microscope, and the average value (arithmetic average value) can be set as the average particle size.

The content of the non-anisotropic filler is preferably 50 to 2500 parts by mass, more preferably 100 to 1500 parts by mass, more preferably 100 to 1500 parts by mass, relative to 100 parts by mass of the total of the polysiloxane (A) and the hydrocarbon compound (B). Preferably it is 200-750 mass parts. By setting it as 50 mass parts or more, the thermal conductivity of a thermally conductive sheet can be made favorable. On the other hand, by setting it as 1500 mass parts or less, a non-anisotropic filler can be suitably dispersed in a binder component, and the effect of the thermal conductivity improvement according to a content can be acquired. In addition, the viscosity of the mixed composition can be prevented from increasing more than necessary.

The mass ratio of the content of the non-anisotropic filler to the content of the anisotropic filler is not particularly limited, but is preferably 0.5 to 5, more preferably 1 to 3, and still more preferably 1.1 to 2.5. By setting the mass ratio within the above range, the non-anisotropic filler is appropriately filled between the anisotropic fillers, and an efficient heat conduction path can be formed, so that the thermal conductivity of the thermally conductive sheet can be further improved.

(additive) In the thermally conductive sheet, various additives can be further blended in the adhesive component within the range that does not impair the function as the thermally conductive sheet. As an additive, at least 1 type or more chosen from a dispersing agent, a coupling agent, an adhesive agent, a flame retardant, an antioxidant, a coloring agent, a precipitation inhibitor, etc. are mentioned, for example. Moreover, when hardening the curable polysiloxane composition (A1) as mentioned above, the hardening catalyst etc. which promote hardening can be blended as an additive. As the hardening catalyst, a platinum-based catalyst may, for example, be mentioned. In addition, as described below, a compatible substance (D) may be blended in the mixed composition. The compatible substance (D) may be volatilized in the process of manufacturing the thermally conductive sheet without remaining in the thermally conductive sheet, and at least a part of the blended compatible substance (D) may remain.

[Manufacturing method of thermally conductive sheet] The thermally conductive sheet of the present invention can be produced, for example, by a production method including the following steps X and Y. Step X: Mix at least the curable polysiloxane composition (A1), the hydrocarbon compound (B), the thermally conductive filler (C) containing the anisotropic filler, and the compatible substance (D) to obtain a mixed composition thing. Step Y: The mixed composition obtained in Step X is hardened by heating. Hereinafter, each step will be described in detail.

(step X) In step X, in addition to mixing the curable polysiloxane composition (A1), the hydrocarbon-based compound (B), and the thermally conductive filler (C) containing the anisotropic filler, a compatible substance (D) is also mixed. ), thereby obtaining a mixed composition. The compatible substance (D) is a substance that is compatible with or dissolved in the hydrocarbon compound (B) and the curable polysiloxane composition (A1). The hydrocarbon-based compound (B) has low compatibility with the curable polysiloxane composition (A1), but can be uniformly mixed with the curable polysiloxane composition (A1) by using the compatible substance (D). middle. Therefore, the hydrocarbon-based compound (B) is also uniformly mixed in the polysiloxane matrix (A) obtained by curing the curable polysiloxane composition (A1).

In step X, as long as the above-mentioned components can be mixed to obtain a mixed composition, the mixing method or mixing order is not particularly limited, and the curable polysiloxane composition (A1) and the hydrocarbon-based compound (B) can be appropriately mixed in any order. ), a thermally conductive filler (C), a compatible substance (D), and other components optionally added as needed to obtain a mixed composition. In addition, as described above, the curable polysiloxane composition (A1) is composed of, for example, a main agent and a curing agent. In this case, the main agent, the curing agent, the hydrocarbon-based compound (B), and the thermally conductive filler may be combined. (C), the compatible substance (D), and other components optionally added as needed are mixed in any order to obtain a mixed composition.

In addition, it is preferable that the hydrocarbon-based compound (B) is dissolved in the compatible substance (D) and mixed with the curable polysiloxane composition (A1) or other components. In this case, the mixture of the hydrocarbon compound (B) and the compatible substance (D), the curable polysiloxane composition (A1) (or the main agent and the curing agent), the thermally conductive filler (C), And other components optionally added as needed are mixed in any order to obtain a mixed composition. If the hydrocarbon-based compound (B) is dissolved in the compatible substance (D) in step X in this way, the hydrocarbon-based compound (B) can be more uniformly mixed in the polysiloxane material (A). In addition, in the case of dissolving the hydrocarbon-based compound (B) in the compatible substance (D), it can be appropriately heated. At this time, the heating temperature is preferably a temperature higher than the melting point of the compatible substance (D), for example, it can be heated to 40° C. or more and dissolved. In addition, in the case of mixing with the main agent and the curing agent, the upper limit of the heating temperature can be set to the temperature at which the thermally conductive polysiloxane is not substantially cured during the mixing process. On the other hand, when mixing the compatible substance (D) with the main ingredient and the curing agent, respectively, it can be set to a temperature at which the compatible substance (D) is not easily volatilized, for example, it can be heated and dissolved at 80° C. or less. Moreover, regarding the mixed state of the polysiloxane material (A) and the hydrocarbon-based compound (B), it is a transparent or slightly cloudy uniform mixture due to the existence of the compatible material (D). On the other hand, when the compatible substance (D) is not contained, the solid hydrocarbon-based compound is dispersed, or the liquid hydrocarbon-based compound is separated into two layers.

<Compatible substance (D)> The compatible substance (D) used in the present invention may be dissolved in the hydrocarbon compound (B) and compatible with the curable polysiloxane composition (A1). The compatible substance (D) is preferably a substance that is liquid at normal temperature (23° C.) and 1 atmosphere. As described below, the compatible substance (D) is, for example, a component volatilized by heating at about 50 to 180° C. in step Y. The compatible substance (D) is volatilized by heating at the time of hardening, whereby the content ratio of the thermally conductive filler (C) in the thermally conductive sheet can be increased. In addition, the viscosity of the mixed composition is reduced by containing the compatible substance (D). Therefore, it becomes easy to increase the blending amount of the thermally conductive filler (C), and further, it becomes easy to align the anisotropic filler in a specific direction by the following magnetic field alignment or the like.

As a compatible substance (D), an alkoxysilane compound, a hydrocarbon-based solvent, an alkoxysiloxane compound, etc. are mentioned. These compounds have high solubility or compatibility with respect to the hydrocarbon-based compound (B) and the curable polysiloxane composition (A1), so in the mixed composition, the hydrocarbon-based compound (B) can be improved in the curable polysiloxane composition. Dispersibility in Silicon Oxide Composition (A1). Thereby, even in the thermally conductive sheet, the hydrocarbon-based compound (B) is appropriately dispersed, and it becomes easy to ensure shape retention, reliability, flexibility at high temperature, and the like. The compatible substance (D) may be used alone or in combination of two or more.

As the compatible substance (D), an alkoxysilane compound is preferably used. By using the alkoxysilane compound, bubbles etc. are not seen on the surface of the thermally conductive sheet obtained by hardening, and the appearance is good. The alkoxysilane compound used as the compatible substance (D) is a compound having the following structure: Among the 4 bonds possessed by the silicon atom (Si), 1 to 3 bonds with alkoxy groups, and the remaining bonds are bonded with alkoxy groups. Organic substituents are bonded. By having an alkoxy group and an organic substituent, the alkoxysilane compound can improve the dispersibility of the hydrocarbon compound (B) in the curable polysiloxane composition (A1). As an alkoxy group which an alkoxysilane compound has, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, and a hexyloxy group are mentioned, for example. The alkoxysilane compound can be contained in the curable polysiloxane composition (A1) as a dimer.

Among the alkoxysilane compounds, from the viewpoint of availability, an alkoxysilane compound having at least one of a methoxy group and an ethoxy group is preferable. From the viewpoints of compatibility and solubility with the curable polysiloxane composition (A1) and the hydrocarbon-based compound (B), the number of alkoxy groups in the alkoxysilane compound is preferably 2 or 3, More preferably, it is 3. Specifically, the alkoxysilane compound is preferably at least one selected from the group consisting of trimethoxysilane compounds, triethoxysilane compounds, dimethoxysilane compounds, and diethoxysilane compounds.

Examples of the functional group contained in the organic substituent of the alkoxysilane compound include acryl group, alkyl group, carboxyl group, vinyl group, methacryloyl group, aromatic group, amino group, isocyanate group group, isocyanurate group, epoxy group, hydroxyl group, and mercapto group. Here, in the case of using a platinum catalyst as the curing catalyst of the curable polysiloxane composition (A1), it is preferable to select an alkoxysilane compound that does not easily affect the curing reaction of the organopolysiloxane. Specifically, when an addition reaction type organopolysiloxane using a platinum catalyst is used, the organic substituent of the alkoxysilane compound preferably does not contain an amine group, an isocyanate group, or an isocyanurate group. group, hydroxyl or mercapto group.

From the viewpoint of improving the dispersibility of the hydrocarbon-based compound (B) in the polysiloxane material (A), the alkoxysilane compound is preferably an alkylalkoxysilane having an alkyl group bonded to a silicon atom compound, that is, an alkoxysilane compound having an alkyl group as an organic substituent. Therefore, a dialkyldialkoxysilane compound and an alkyltrialkoxysilane compound are preferable, and an alkyltrialkoxysilane compound is especially preferable. The number of carbon atoms of the alkyl group bonded to the silicon atom may be, for example, 1-16. In addition, in trialkoxysilane compounds such as trimethoxysilane compounds and triethoxysilane compounds, from the viewpoint of improving the dispersibility of the hydrocarbon-based compound, the number of carbon atoms in the alkyl group is preferably 6 or more, and more It is preferably 8 or more, and the number of carbon atoms is preferably 12 or less, more preferably 10 or less. On the other hand, in a dialkoxysilane compound such as a dimethoxysilane compound and a triethoxysilane compound, the above-mentioned alkyl group may have 1 or more carbon atoms from the viewpoint of improving the dispersibility of the hydrocarbon-based compound. , and the number of carbon atoms is preferably 10 or less, more preferably 6 or less, and still more preferably 4 or less.

Examples of the alkyl group-containing alkoxysilane compound include methyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane, methyl Triethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane , isobutyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, Methylcyclohexyldimethoxysilane, methylcyclohexyldiethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethyl Oxysilane, etc. Among the alkyl group-containing alkoxysilane compounds, from the viewpoint of improving the dispersibility of the hydrocarbon-based compound (B), n-decyltrimethoxysilane and dimethyldimethoxysilane are further preferred. Silane and n-octyltriethoxysilane are more preferably n-decyltrimethoxysilane and n-octyltriethoxysilane from the viewpoint of solubility with the hydrocarbon compound (B).

The alkoxysiloxane compound used as the compatible substance (D) has a structure having two or more siloxane bonds, and at least one silicon atom is bonded to an alkoxy group. The alkoxysiloxane compound has a structure in which "at least one silicon atom among the silicon atoms constituting the siloxane bond is bonded to an organic substituent". The alkoxysiloxane compound can improve the dispersibility of the hydrocarbon compound (B) by having an alkoxy group and an organic substituent. As the alkoxy group and the organic substituent which the alkoxysiloxane compound has, those exemplified in the description of the above-mentioned alkoxysilane compound can be exemplified from the viewpoint of improving the dispersibility of the hydrocarbon-based compound (B). , preferably at least an alkyl group.

Examples of the alkoxysiloxane compound include methylmethoxysiloxane oligomers, methylphenylmethoxysiloxane oligomers, and methylepoxymethoxysiloxane oligomers. Alkane oligomers, methylmercaptomethoxysiloxane oligomers, and methacryloylmethoxysiloxane oligomers, etc. As the alkoxysiloxane compound, one type or two or more types may be used.

As the hydrocarbon-based solvent used as the compatible substance (D), an aromatic hydrocarbon-based solvent may, for example, be mentioned. Among them, from the viewpoint of compatibility with the curable polysiloxane composition (A1), an aromatic hydrocarbon-based solvent is preferred. Examples of the aromatic hydrocarbon-based solvent include aromatic hydrocarbon-based solvents having about 6 to 10 carbon atoms, and examples thereof include toluene, xylene, 1,3,5-trimethylbenzene, ethylbenzene, propylbenzene, and butylbenzene. , tertiary-butylbenzene, etc., preferably toluene, xylene, etc.

In the mixed composition, the content of the compatible substance (D) is preferably 6 to 60 parts by mass relative to 100 parts by mass in total of the curable polysiloxane composition (A1) and the hydrocarbon compound (B). If it is 6 parts by mass or more, the mixing uniformity of the hydrocarbon-based compound (B) with respect to the curable polysiloxane composition (A1) can be sufficiently improved. Moreover, by setting it as 60 mass parts or less, the effect commensurate with the usage-amount of a compatible substance (D) can be acquired. From these viewpoints, it is more preferable that the said content of a compatible substance (D) is 10-50 mass parts, More preferably, it is 15-45 mass parts. At this time, when the mixing of the hydrocarbon-based compound (B) is not uniform, the hydrocarbon-based compound is not completely dissolved, for example, the solid hydrocarbon-based compound may be dispersed. Such dispersed solids may have properties as fillers in the mixed composition. That is, since the undissolved solid material becomes a part of the filler which raises a viscosity, there exists a possibility that the compounding quantity of a thermally conductive filler cannot be easily increased as a result. In addition, in the mixed composition, from the viewpoint of improving the dispersibility of the hydrocarbon-based compound (B), the content of the compatible substance (D) is preferably larger than the content of the hydrocarbon-based compound (B). Furthermore, it is preferable that a part or all of the compatible substance (D) is volatilized by heating in step Y. Therefore, the compatible substance (D) may not be contained in the thermally conductive sheet, or may be contained in the thermally conductive sheet in an amount smaller than the content in the mixed composition.

Furthermore, the components other than the compatible substance (D) in the mixed composition (ie curable polysiloxane composition (A1), hydrocarbon compound (B), thermally conductive filler (C), other additives, etc.) The detailed description is as above. In addition, the content of the hydrocarbon-based compound (B) and the thermally conductive filler (C) in the mixed composition is also as described above. In the above, the content of each component is expressed as an amount based on 100 parts by mass of the total of the polysiloxane (A) and the hydrocarbon-based compound (B), and in the mixed composition, the curable polysiloxane is used. The amount based on 100 parts by mass in total of the composition (A1) and the hydrocarbon compound (B).

(step Y) Step Y is a step of hardening the mixed composition by heating. The temperature when heating the mixed composition is not particularly limited as long as the curable polysiloxane composition (A1) can be cured by heating, and it is not particularly limited as long as it is higher than room temperature (23°C), preferably 50 Heating at a temperature above ℃. In addition, the heating temperature is not particularly limited, as long as the thermally conductive sheet and the mixed composition are not thermally deteriorated, for example, 180°C or lower, preferably 150°C or lower. In addition, the heating of the mixed composition may be performed in one stage, or may be performed in two or more stages. In the case of performing two or more stages, the heating temperature may be within the above-mentioned range in at least any one of the stages, and it is preferable to make the heating temperature within the above-mentioned range in all the stages. In addition, the total heating time is, for example, about 10 minutes to 3 hours. Moreover, when carrying out two or more stages, for example, the mixed composition can be semi-hardened in the first stage, and the mixed composition can be completely hardened by heating after the second stage.

In step Y, the mixed composition can be formed into a specific shape such as a block or a sheet, and then heated and hardened. Moreover, in step Y, the mixed composition can be hardened by heating after aligning the anisotropic filler used as the thermally conductive filler (C) in a single direction. The anisotropic filler can be aligned by the magnetic field alignment method, the flow alignment method, preferably by the magnetic field alignment method.

In the magnetic field alignment method, the mixed composition can be injected into a mold or the like, and then placed in a magnetic field to align the anisotropic filler along the magnetic field. Next, an alignment molded body can be obtained by hardening the curable polysiloxane composition (A1). Hardening of the mixed composition can be carried out by heating conditions as described above. The alignment molded body is preferably in the form of a block, but may also be in the form of a sheet. By forming into a sheet shape, the alignment molded body can be directly used as a thermally conductive sheet without dicing. On the other hand, the orientation of the anisotropic filler can be improved by making it into a block shape.

In the magnetic field alignment method, a release film may be disposed on a portion of the mold that is in contact with the mixed composition. As the release film, for example, a resin film having good releasability, or a resin film that has been peeled off with a release agent or the like on one side can be used. By using the release film, the alignment molded body can be easily released from the mold.

In order to align the magnetic field, the viscosity of the mixed composition used in the magnetic field alignment method is preferably 10-300 Pa·s. By setting it as 10 Pa·s or more, the thermal conductive filler (C) becomes less likely to precipitate. In addition, by setting it to 300 Pa·s or less, the fluidity becomes good, the anisotropic filler is properly aligned in the magnetic field, and the abnormality that the alignment takes too much time does not occur. Furthermore, the viscosity refers to the viscosity measured at 25°C and 10 rpm using a rotational viscometer (Brookfield viscometer DV-E, spindle SC4-14). Among them, when using a thermally conductive filler (C) that is not easy to precipitate, or combining additives such as a precipitation inhibitor, the viscosity of the mixed composition may be less than 10 Pa·s.

In the magnetic field alignment method, as a source for generating magnetic lines of force for applying magnetic lines of force, superconducting magnets, permanent magnets, electromagnets, etc. can be exemplified. In terms of generating a magnetic field with a higher magnetic flux density, it is preferable to use superconducting magnet. The magnetic flux density of the magnetic field generated by the magnetic field line generating sources is preferably 1 to 30 tesla. When the magnetic flux density is set to 1 tesla or more, the above-mentioned anisotropic filler made of a carbon material or the like can be easily aligned. Moreover, by setting it as 30 tesla or less, it can manufacture practically.

In the flow alignment method, shear force is applied to the mixed composition to produce a primary sheet in which the anisotropic filler is aligned in the plane direction. More specifically, in the flow alignment method, first, a shear force is imparted to the mixed composition prepared in the step X while being flatly extended to be formed into a sheet shape (primary sheet). By applying shear force, the anisotropic filler can be aligned in the shear direction. As the sheet forming means, for example, the mixed composition can be applied on the base film by a coating applicator such as a rod coater or a doctor blade, or by extrusion molding or by discharging from a nozzle. Subsequently, drying may be performed as necessary, or the mixed composition may be semi-hardened or fully hardened. The thickness of the primary sheet is preferably about 50 to 5000 μm. In the primary sheet, the anisotropic filler material is oriented in a single direction along the face direction of the sheet. The mixed composition used in the flow alignment method has a relatively high viscosity in order to be subjected to shearing force when extending into a sheet. Specifically, the viscosity of the mixed composition is preferably 3 to 500 Pa·s.

As described below, the primary sheet can be used directly as a thermally conductive sheet without being formed into a block. In addition, after stacking a plurality of primary sheets so that the alignment direction is the same, they can be hardened by heating if necessary, and the primary sheets can be bonded to each other by hot pressing or the like, thereby forming a laminated block (block-shaped). the alignment forming body). Moreover, when forming a laminated block, after irradiating vacuum ultraviolet rays to at least one of the surfaces where the primary sheets overlap each other, the primary sheets may be stacked. If the primary sheets are overlapped via the surface irradiated with vacuum ultraviolet rays, the primary sheets can be firmly attached to each other. In addition, in the case of irradiating vacuum ultraviolet rays, the mixed composition can be completely cured in advance when the primary sheets are produced, and when the primary sheets are stacked to form a laminated block, it is not necessary to cure by heating or the like. In the flow alignment method, the hardening of the mixed composition can also be performed by the heating conditions as described above.

As described above, when forming a block-shaped aligned molded body, the resulting aligned molded body may be cut perpendicularly to the direction in which the anisotropic filler is aligned by slicing or the like, to form a sheet-like molded body. Slicing can be performed, for example, with a knife or the like. The sheet-like molded body is cut by slicing or the like, and the front end of the anisotropic filler is exposed from the adhesive component on each surface serving as the cut surface. The sheet-like molded body obtained by cutting can be used as a thermally conductive sheet as it is, and other treatments can be further performed. For example, grinding or the like may be performed on each surface as the cut surface. Grinding of the surface can be performed, for example, using sandpaper.

[How to use the thermally conductive sheet] The thermally conductive sheet of the present invention is used in electronic equipment and the like. Specifically, the thermally conductive sheet is interposed between the two members to conduct heat from one of the members to the other. Specifically, the thermally conductive sheet is interposed between the heat-generating body and the heat-dissipating body, so that the heat emitted by the conduction heat-generating body moves to the heat-dissipating body, and is dissipated by the heat-dissipating body. Here, as a heat generating body, various electronic components, such as CPU, a power amplifier, and a power supply used inside an electronic apparatus, are mentioned. Moreover, as a heat sink, a radiator, a heat pump, the metal case of an electronic apparatus, etc. are mentioned, for example. Both surfaces of the thermally conductive sheet can be in close contact with each of the heat generating body and the heat sink, respectively, and can be used by being compressed.

[Assembly method of thermally conductive sheet] The present invention also provides an assembly method of the thermally conductive sheet. As described above, the thermally conductive sheet of the present invention includes a binder component and a thermally conductive filler (C), the binder component being a mixture of a polysiloxane (A) and a hydrocarbon compound (B), and the thermally conductive filler (C) is dispersed in the adhesive component; the thermally conductive filler (C) contains anisotropic fillers oriented in the thickness direction; and the thermally conductive sheet has a thickness of 0.05 to 0.5 mm. The thermally conductive sheet of the present invention can be stably assembled between two members (between the first and second members) by the assembly method having the following steps 1 to 3.

Step 1: The step of disposing the above-mentioned thermally conductive sheet on the surface of the first member. Step 2: The step of heating the thermally conductive sheet. Step 3: A step of disposing the second member on the surface of the thermally conductive sheet on the opposite side to the surface on the side of the first member, and pressing the thermally conductive sheet to mount the thermally conductive sheet between the first and second members . In this assembling method, the first and second members are not particularly limited, as long as one of them is a heat generating body and the other is a heat sink. The detailed description of the heating element and the radiating element is as described above.

(step 1) In step 1, the thermally conductive sheet is arranged on the surface of the first member. The arrangement method of the thermally conductive sheet is not particularly limited, and it may be arranged so that one surface of the thermally conductive sheet is in contact with the first member. In this method, step 2 is preferably performed after step 1, as described below. In this case, since the thermally conductive sheet is disposed on the surface of the first member in a state of plasticity before heating, the workability of step 1 is good.

(step 2) In step 2, the thermally conductive sheet is heated. Step 2 may be performed after step 1, may be performed before step 1, or may be performed simultaneously with step 1. As mentioned above, step 2 is preferably performed after step 1. That is, in step 2, it is preferable to heat the thermally conductive sheet arrange|positioned on the surface of the 1st member.

In step 2, the thermally conductive sheet may be heated to a temperature equal to or higher than the melting point of the hydrocarbon-based compound (B). Therefore, the thermally conductive sheet can be heated to a temperature higher than normal temperature (23°C), the hydrocarbon-based compound (B) can be surely melted, and the flexibility of the thermally conductive sheet can be improved at the time of mounting (step 3 below). In other words, it is preferably heated to 40°C or higher, more preferably 50°C or higher, and still more preferably 60°C or higher. Moreover, from the viewpoint of preventing the thermally conductive sheet from being heated more than necessary, the thermally conductive sheet may be heated to 100°C or lower, preferably 90°C or lower, and more preferably 85°C or lower. In step 2, if the thermally conductive sheet is heated to the melting point of the hydrocarbon-based compound (B) or higher, the molten hydrocarbon-based compound (B) can be easily fixed to the first and 2nd member.

The heating method of the thermally conductive sheet is not particularly limited, and the thermally conductive sheet can be heated by a heating device such as an infrared heater, a hot air heater, and a heat transfer heater. In the past, the phase change sheet was generally softened or melted by heating the heating element constituting any one of the first and second members. The other heating devices are heated before being sandwiched between the first and second members. According to this aspect, it becomes possible to fix the thermally conductive sheet to the first and second members before using the electronic device. Therefore, it also becomes possible to compress the thermally conductive sheet with a predetermined compressibility and the like and perform installation.

(step 3) In step 3, the 2nd member is arrange|positioned on the surface opposite to the 1st member side of the thermally conductive sheet, and the thermally conductive sheet is pressurized, and the thermally conductive sheet is attached between the 1st and 2nd members. In step 3, the thermally conductive sheet can be placed in a state of being sandwiched between the first and second members by further disposing the second member on the thermally conductive sheet disposed on the surface of the first member. Step 3 may be performed simultaneously with step 2, preferably performed after step 2. Therefore, in step 3, the second member can be further arranged on "the thermally conductive sheet that has been arranged on the surface of the first member and has been heated". Furthermore, in this assembling method, it is more preferable to carry out step 1, step 2, and step 3 in the order. When the steps are performed in this order, workability is improved.

In step 3, the thermally conductive sheet sandwiched between the first and second members is heated by step 2. Therefore, in step 3, in the heated state, it can be further heated in the thickness direction. pressure. Here, the pressurization can be performed by, for example, further pressing the thermally conductive sheet sandwiched between the first and second members in the thickness direction by the first and second members. Moreover, when the thermally conductive sheet is pressurized in step 3, the temperature becomes a temperature equal to or higher than the melting point of the hydrocarbon-based compound (B), and the hydrocarbon-based compound (B) is melted, so that the molten hydrocarbon-based compound (B) can The thermally conductive sheet is fixed to the first and second members.

As described above, the thermally conductive sheet of the present invention has more than a certain degree of flexibility in a heated state, so that it can follow the first and second members by pressing in step 3. Therefore, even if the first and second members have irregularities, the thermally conductive sheet can be brought into close contact with the first and second members, thereby preventing an increase in thermal resistance. Moreover, the thermally conductive sheet can be attached without applying high stress to the first and second members. Furthermore, since the thermally conductive sheet has shape retention properties even when heated, even when it is used in a compressed state, pumping can be suppressed and reliability can be improved. Furthermore, the thermally conductive sheet has a certain plasticity before heating, so the workability during installation can be improved.

[Heat dissipation member] The present invention also provides a heat-dissipating member comprising the above-mentioned thermally conductive sheet and a heat-dissipating body, wherein the thermally-conductive sheet is assembled on the surface of the heat-dissipating body. Such a heat dissipation member can be obtained by, for example, arranging a thermally conductive sheet on the surface of the heat sink and fixing the thermally conductive sheet to the surface of the heat sink. Here, the thermally conductive sheet can be fixed to the surface of the heat sink by heating to a temperature equal to or higher than the melting point of the hydrocarbon-based compound (B) and applying pressure, for example. In this case, the thermally conductive sheet may be disposed on the surface of the heat sink after being heated, or may be heated after being disposed on the surface of the heat sink.

In addition, the heat-dissipating member can be installed between the heat-dissipating body and the heat-emitting body by arranging the heat-dissipating body on the surface on the opposite side of the heat-dissipating body side of the thermally-conductive sheet. As the assembling method, it is sufficient to carry out the method including the above-mentioned steps 2 and 3, and the details thereof are omitted as described above. [Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples at all.

The thermally conductive sheets obtained in the present examples and comparative examples were evaluated by the following methods.

[Thermal resistance value, slope α] The thermal resistance value was measured by the method shown below using the thermal resistance measuring machine shown in FIG. 1 . Specifically, for each sample, a test piece S having a size of 30 mm×30 mm was produced and used for this test. Then, each test piece S is attached to the copper block 22 whose measurement surface is 25.4 mm×25.4 mm and the side surface is covered by the heat insulating material 21 , and is sandwiched by the copper block 23 above, and pressure is applied by the load cell 26 . 40 psi (0.276 MPa) load. Here, the lower copper block 22 is in contact with the heater 24 . In addition, the upper copper block 23 is covered with a heat insulating material 21, and is connected to a radiator 25 with a fan. Next, the heater 24 was heated to make the temperature substantially constant, and after 10 minutes, the temperature (θ _j0 ) of the upper copper block 23 , the temperature (θ _j1 ) of the lower copper block 22 , and the temperature of the heater were measured. As for the calorific value (Q), the thermal resistance value R ₄₀ of each sample was obtained according to the following formula (2). In addition, regarding the temperature, the calorific value was adjusted so that a thermally conductive sheet might be 80 degreeC. Thermal resistance value=(θ _j1 -θ _j0 )/Q... Equation (2) In Equation (2), θ _j1 is the temperature of the lower copper block 22 , θ _j0 is the temperature of the upper copper block 23 , Q is the calorific value.

The thermal resistance value R ₁₀ was calculated in the same manner as described above, except that a load of 10 psi (0.069 MPa) was applied by the load cell 26 . Based on the thermal resistance value R ₄₀ (°C·in ² /W) measured at a load of 40 psi calculated in the above-mentioned manner, the thickness of the thermally conductive sheet measured at a load of 40 psi T ₄₀ (mm), The thermal resistance value R ₁₀ (°C·in ² /W) measured at 10 psi, the thickness T ₁₀ (mm) of the thermally conductive sheet when measured at a load of 10 psi, and the slope is calculated using the following formula (1) a. α=(R ₄₀ -R ₁₀ )/(T ₄₀ -T ₁₀ )...(1)

The thermal resistance value at low load is based on the value of the slope α, and is evaluated according to the following criteria. A Slope α is 0.1 or less B Slope α exceeds 0.1 and is 0.4 or less C Slope α exceeds 0.4 and is 1 or less D Slope α exceeds 1

[Compression ratio] The thermally conductive sheet was cut with a size of 10 mm × 10 mm, and the compressibility was measured at 0.276 MPa (=40 psi) at 80°C. Specifically, a test piece with a size of 10 mm × 10 mm is sandwiched between a base with a flat surface and an extrusion head that is squeezed in parallel, and the thickness T2 when the test piece is compressed at 0.276 MPa is measured, and the thickness T2 is calculated. Compression ratio (%) relative to the initial thickness T1 [100×(T1-T2)/T1].

[Example 1] The side chain crystalline polyα-olefin (CPAO, melting point (Tm): 42°C) as the hydrocarbon-based compound (B) and n-decyltrimethoxysilane as the compatible substance (D) were mixed with the mixture in Table 1. The combined amount was mixed at 23°C to obtain a mixture in which the hydrocarbon compound (B) was dissolved in the compatible substance (D). The resulting mixture, polysiloxane main agent 1 (alkenyl-containing organopolysiloxane) as curable polysiloxane composition (A1), polysiloxane hardener (hydrogenated organopolysiloxane), and After the catalyst (platinum-based catalyst) was uniformly mixed, it was mixed with the thermally conductive filler (C) in the amount shown in Table 1 to obtain a mixed composition.

In addition, regarding the thermally conductive filler (C), aluminum powder (spherical, average particle size of 3 μm, aspect ratio of 1 to 1.5, thermal conductivity of 236 W/m·K) was used as the non-anisotropic filler. In addition, as anisotropic fillers, flake graphite powder (average particle size 40 μm, aspect ratio 10, thermal conductivity 550 W/m·K), graphitized carbon fiber 1 (average fiber length 77 μm, aspect ratio 8, thermal conductivity 1) were used 1200 W/m·K), and graphitized carbon fiber 2 (average fiber length 150 μm, aspect ratio 15, thermal conductivity 900 W/m·K). In addition, the volume filling rate of the thermal conductive filler (C) in each Example and the comparative example was 66 volume%. In addition, the melting point is the temperature of the endothermic peak of the DTA curve measured by thermogravimetric differential thermal analysis (TGDTA, "DTG-60" manufactured by Shimadzu Corporation) at a temperature increase rate of 1°C/min.

Then, the above-mentioned mixed composition was injected into the mold "set to be thick enough compared with the thermally conductive sheet", and a magnetic field of 8 T was applied along the thickness direction to align the anisotropic filler along the thickness direction, and then at 80°C. The curable polysiloxane composition (A1) was cured by heating at ℃ for 60 minutes, and a block-shaped oriented molding was obtained. Next, using a cutter, the block-shaped aligned molded body was sliced into a sheet shape to obtain a sheet-shaped molded body with exposed anisotropic fillers, and then further heated at 150° C. for 2 hours to obtain the sheet-shaped molded body. A thermally conductive sheet is made. Regarding the thermally conductive sheet, two types of those having a thickness of 0.2 mm and those having a thickness of 0.3 mm were produced. For each thermally conductive sheet, the thermal resistance value R ₄₀ measured at a load of 40 psi and the thickness T ₄₀ at the time of measurement, the thermal resistance value R ₁₀ measured at a load of 10 psi and the thickness T ₁₀ at the time of measurement were measured as described above, and calculated slope α, and evaluate the thermal resistance at low load. The results are shown in Table 1.

[Examples 2 to 4] A thermally conductive sheet was obtained in the same manner as in Example 1, except that the blending amount of each component was changed to the amount described in Table 1. Regarding the thermally conductive sheet, two types of those having a thickness of 0.2 mm and those having a thickness of 0.3 mm were produced. For each thermally conductive sheet, the thermal resistance value R ₄₀ measured at a load of 40 psi and the thickness T ₄₀ at the time of measurement, the thermal resistance value R ₁₀ measured at a load of 10 psi and the thickness T ₁₀ at the time of measurement were measured as described above, and calculated slope α, and evaluate the thermal resistance at low load. The results are shown in Table 1.

[Example 5] Except that the blending amount of the side chain crystalline polyα-olefin (CPAO) was as shown in Table 1, and dimethyldimethoxysilane was used as the compatible substance (D), the A thermally conductive sheet was obtained in the same manner as in Example 1. Furthermore, in Example 5, although the hydrocarbon-based compound (B) tends to be difficult to dissolve in the compatible substance (D), and the dissolution is time-consuming, a thermally conductive sheet was successfully obtained. Regarding the thermally conductive sheet, two types of those having a thickness of 0.2 mm and those having a thickness of 0.3 mm were produced. For each thermally conductive sheet, the thermal resistance value R ₄₀ measured at a load of 40 psi and the thickness T ₄₀ at the time of measurement, the thermal resistance value R ₁₀ measured at a load of 10 psi and the thickness T ₁₀ at the time of measurement were measured as described above, and calculated slope α, and evaluate the thermal resistance at low load. The results are shown in Table 1.

[Example 6] A thermally conductive sheet was obtained in the same manner as in Example 1, except that white petrolatum in the Japanese Pharmacopoeia was used as the hydrocarbon compound (B) in accordance with the compounding amount in Table 1. Regarding the thermally conductive sheet, two types of those having a thickness of 0.2 mm and those having a thickness of 0.3 mm were produced. For each thermally conductive sheet, the thermal resistance value R ₄₀ measured at a load of 40 psi and the thickness T ₄₀ at the time of measurement, the thermal resistance value R ₁₀ measured at a load of 10 psi and the thickness T ₁₀ at the time of measurement were measured as described above, and calculated slope α, and evaluate the thermal resistance at low load. The results are shown in Table 1.

[Comparative Examples 1 and 2] The same manner as in Example 1 was carried out, except that the hydrocarbon-based compound (B) was not used, and each component was blended and mixed according to Table 1 to obtain a mixed composition to prepare a thermally conductive sheet. Table 1 shows the evaluation results of the thermally conductive sheets obtained in Comparative Examples 1 and 2.

[Comparative Example 3] A mixed composition was obtained by mixing the components according to Table 1 without using the compatible substance (D), except that the same procedure as in Example 1 was carried out, except that the hydrocarbon-based compound (B) was not dispersed. In the curable polysiloxane composition (A1), a block-shaped oriented molded body could not be obtained.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Blending (parts by mass) Curable polysiloxane composition (A1) Polysiloxane main agent 90.0 88.2 86.4 81.8 81.8 81.8 90.9 90.9 81.8 Silicone hardener 9.0 8.8 8.6 8.2 8.2 8.2 9.1 9.1 8.2 additive catalyst 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Hydrocarbon compound (B) CPAO 1 3 5 10 5 10 white vaseline 5 Thermally conductive filler (C) Aluminum powder 3 μm (average particle size) 243 243 243 243 243 243 243 255 243 Flake graphite powder 40 μm (average long axis length) 20 20 20 20 20 20 20 20 Graphitized carbon fiber 1 77 μm (average fiber length) 140 140 140 140 140 140 140 110 140 Graphitized carbon fiber 2 150 μm (average fiber length) 10 10 10 10 10 10 10 30 10 Compatible substances (D) n-Decyltrimethoxysilane twenty two twenty two twenty two twenty two twenty two twenty two Dimethyldimethoxysilane twenty two Measurement result A (0.2 mmt) 10 psi thermal resistance R ₁₀ (℃·in ² /W) 80℃ 0.026 0.021 0.024 0.024 0.026 0.023 0.031 0.033 - 40 psi thermal resistance R ₄₀ (℃·in ² /W) 80℃ 0.019 0.020 0.022 0.018 0.022 0.021 0.022 0.023 - Thickness T ₁₀ (mm) at 10 psi 0.196 0.158 0.216 0.183 0.195 0.196 0.190 0.170 - Thickness T ₄₀ (mm) at 40 psi 0.160 0.136 0.193 0.159 0.172 0.164 0.166 0.156 - Compression % at 40 psi 27% 29% twenty four% 29% 26% 26% 18% 18% - α _{( 0.2 mm )} 0.194 0.045 0.065 0.250 0.174 0.062 0.375 0.714 - Measurement result B (0.3 mmt) 10 psi thermal resistance R ₁₀ (℃·in ² /W) 80℃ 0.030 0.025 0.024 0.025 0.027 0.025 0.039 0.046 - 40 psi thermal resistance R ₄₀ (℃·in ² /W) 80℃ 0.023 0.022 0.024 0.021 0.024 0.022 0.024 0.024 - Thickness T ₁₀ (mm) at 10 psi 0.294 0.289 0.280 0.263 0.279 0.283 0.261 0.265 - Thickness T ₄₀ (mm) at 40 psi 0.266 0.260 0.257 0.236 0.253 0.249 0.237 0.252 - Compression % at 40 psi 19% 20% twenty two% 27% 20% twenty three% 14% 14% - α _{( 0.3 mm )} 0.250 0.097 0.017 0.148 0.115 0.088 0.625 1.692 - Thermal resistance at low load B A A B B A C D -

The thermally conductive sheets of Examples 1 to 6 satisfy the requirements of the present invention, have high compressibility at high temperatures, and are excellent in flexibility. In addition, these thermally conductive sheets are not affected by the thin thickness, the value of the slope α is still small, and under low load, the followability to the heating element or the radiator is still excellent, and the thermal resistance value is low. In particular, the thermally conductive sheets of Examples 2, 3, and 6 have lower slope α values, and their thermal resistance values under low load are especially low. It is obtained by blending the hydrocarbon-based compound (B) in a range of not less than 8 parts by mass and not more than 8 parts by mass, and using n-decyltrimethoxysilane as a compatible substance (D). The thermally conductive sheet obtained in each example is a relatively rigid sheet at room temperature lower than the melting point of the hydrocarbon-based compound (B), so the thermally conductive sheet can be obtained by slicing as described above, and is excellent in handleability. Moreover, even if it did not become liquid at 80 degreeC, and a liquid substance did not flow out, even if it compresses for a long time, there will be no pumping out, etc., and reliability is good. Furthermore, bubbles etc. were not seen on the surface of the thermally conductive sheet, and the appearance was relatively good. The thermally conductive sheets of Comparative Examples 1 and 2 had low compressibility at high temperature and did not have certain flexibility. In addition, the value of the slope α is larger than that of the examples, and when the load is low, the followability to the heating element or the radiating element becomes insufficient, and the thermal resistance value is high. In Comparative Example 3, since the compatible substance (D) was not used, a thermally conductive sheet could not be obtained.

21: heat insulating material 22: lower copper block 23: upper copper block 24: heater 25: radiator 26: load cell S: test piece θ _j0 : temperature of the upper copper block θ _j1 : lower temperature of copper block

Fig. 1 is a diagram illustrating a measuring machine for measuring thermal resistance.

Claims (11)

A thermally conductive sheet having: A binder component, which is a mixture of a polysiloxane (A) and a hydrocarbon compound (B); and A thermally conductive filler (C) dispersed in the above-mentioned adhesive composition; The above-mentioned thermally conductive filler (C) contains anisotropic filler oriented in the thickness direction; and The thickness of the thermally conductive sheet is 0.05-0.5 mm. The thermally conductive sheet as claimed in claim 1, wherein, according to the thermal resistance value R ₄₀ (°C·in ² /W) measured at 80°C and a load of 40 psi, and the thickness T ₄₀ (mm) at the time of measurement, and at 80°C, The thermal resistance value R ₁₀ (°C·in ² /W) measured at a load of 10 psi and the thickness T ₁₀ (mm) at the time of measurement, the slope α expressed by the following formula (1) calculated by the following formula (1) is 0.4 or less, α = (R ₄₀ -R ₁₀ )/(T ₄₀ -T ₁₀ )...(1). The thermally conductive sheet according to claim 1 or 2, wherein the melting point of the hydrocarbon-based compound (B) is higher than 23°C and 80°C or lower. The thermally conductive sheet according to any one of claims 1 to 3, wherein the hydrocarbon-based compound (B) is a crystalline polyα-olefin. The thermally conductive sheet according to any one of claims 1 to 4, wherein the content of the hydrocarbon-based compound (B) is 0.5 with respect to 100 parts by mass in total of the polysiloxane material (A) and the hydrocarbon-based compound (B). ~15 parts by mass. The thermally conductive sheet according to any one of claims 1 to 5, wherein the volume filling rate of the thermally conductive filler (C) is 30 to 85% by volume. A heat-dissipating member comprising the thermally conductive sheet of any one of claims 1 to 6 and a heat-dissipating body, wherein the thermally-conductive sheet is mounted on a surface of the heat-dissipating body. A method for assembling a thermally conductive sheet, comprising the following steps: The step of disposing a thermally conductive sheet on the surface of the first member, the thermally conductive sheet has an adhesive component and a thermally conductive filler (C), and the adhesive component is a polysiloxane (A) and a hydrocarbon compound (B) The mixture, the thermally conductive filler (C) is dispersed in the above-mentioned adhesive component; the above-mentioned thermally conductive filler (C) contains anisotropic fillers oriented along the thickness direction; and the thickness of the thermally conductive sheet is 0.05～0.5 mm; the step of heating the above-mentioned thermally conductive sheet; and The second member is arranged on the surface on the opposite side to the surface on the side of the first member of the thermally conductive sheet, the thermally conductive sheet is pressurized, and the thermally conductive sheet is attached between the first and second members steps. The method for assembling a thermally conductive sheet according to claim 8, wherein the hydrocarbon-based compound (B) has a melting point higher than 23° C., and the thermally conductive sheet is heated to the melting point or higher. A method of manufacturing a thermally conductive sheet, comprising the following steps: At least the curable polysiloxane composition (A1), the hydrocarbon compound (B), the thermally conductive filler (C) containing the anisotropic filler, and the compatible substance (D) are mixed to obtain a mixed composition. steps; and The step of hardening the above mixed composition by heating. The method for producing a thermally conductive sheet according to claim 10, wherein the compatible substance (D) is an alkoxysilane compound.

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