WO2016068157A1 - 熱伝導シート、熱伝導シートの製造方法、放熱部材及び半導体装置 - Google Patents
熱伝導シート、熱伝導シートの製造方法、放熱部材及び半導体装置 Download PDFInfo
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- WO2016068157A1 WO2016068157A1 PCT/JP2015/080303 JP2015080303W WO2016068157A1 WO 2016068157 A1 WO2016068157 A1 WO 2016068157A1 JP 2015080303 W JP2015080303 W JP 2015080303W WO 2016068157 A1 WO2016068157 A1 WO 2016068157A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
- H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates to a heat conductive sheet disposed between a heating element such as a semiconductor element and a heat radiator such as a heat sink, a method for manufacturing the heat conductive sheet, a heat radiating member including the heat conductive sheet, and a semiconductor device.
- a heat conduction sheet is provided between the semiconductor device and the heat sink in order to efficiently release the heat of the semiconductor device.
- a heat conductive sheet a material in which a heat conductive filler [for example, scaly particles (boron nitride (BN), graphite, etc.), carbon fiber, etc.] is dispersed and contained in a silicone resin is widely used (Patent Document 1). reference).
- heat conductive fillers have anisotropy of heat conduction.
- a heat of about 600 W / m ⁇ K to 1200 W / m ⁇ K in the fiber direction.
- boron nitride when used, it has a thermal conductivity of about 110 W / m ⁇ K in the plane direction and about 2 W / m ⁇ K in the direction perpendicular to the plane direction. It is known to have.
- thermally conductive filler is buried in the sheet body in order to ensure the electrical insulation of the thermally conductive sheet, the effect of high thermal conductivity by the thermally conductive filler is impaired.
- the present invention is a thermal conductive sheet that can ensure electrical insulation and maintain high thermal conductivity even in unexpected situations such as contact of the thermal conductive sheet, a method for manufacturing the thermal conductive sheet, An object is to provide a heat dissipation member and a semiconductor device.
- a heat conductive sheet according to the present invention has a sheet body in which a heat conductive resin composition containing a binder resin and carbon fibers covered with an insulating film is cured, The carbon fibers exposed on the surface of the sheet body are not covered with the insulating film and are covered with the binder resin component.
- the method for producing a heat conductive sheet according to the present invention includes forming a heat conductive resin composition containing a binder resin and a carbon fiber covered with an insulating film into a predetermined shape and curing the composition. Obtaining a molded body of the thermally conductive resin composition; Cutting the molded body into a sheet and obtaining a sheet body; Covering the carbon fiber exposed on the surface of the sheet body with a component of the binder resin, In the step of obtaining the sheet body, the insulating film covering the carbon fibers exposed on the surface of the sheet body is removed.
- the heat dissipating member according to the present invention includes a heat spreader that dissipates heat generated by an electronic component, and the heat conductive sheet that is disposed on the heat spreader and is sandwiched between the heat spreader and the electronic component. is there.
- the semiconductor device includes a heat spreader that dissipates heat generated by the semiconductor element, and the heat conductive sheet that is disposed on the heat spreader and is sandwiched between the heat spreader and the semiconductor element. It is.
- the carbon fiber exposed on the surface of the sheet body is not covered with the insulating film, it is possible to suppress a decrease in thermal conductivity due to the insulating film.
- the heat conductive sheet according to the present invention is coated with the binder resin component on the carbon fiber that is exposed on the surface of the sheet body and is not covered with the insulating film, the sheet has both insulating properties and heat conductivity. can do.
- FIG. 1 is a cross-sectional view showing a heat conductive sheet, a heat radiating member, and a semiconductor device to which the present invention is applied.
- FIG. 2 is a perspective view showing a process of slicing the resin molded body and cutting out the sheet body.
- FIG. 3A is a perspective view showing a sheet body cut out from a resin molded body.
- FIG. 3B is a perspective view showing a state in which the sheet body is covered with a binder resin component.
- FIG. 4 is a perspective view showing a carbon fiber covered with an insulating film.
- FIG. 5 is a cross-sectional view showing an example of the surface shape of the heat conductive sheet.
- FIG. 6 is a cross-sectional view showing another example of the surface shape of the heat conductive sheet.
- FIG. 7 is a perspective view illustrating a state in which the sheet body is pressed through the spacer.
- a heat conductive sheet 1 to which the present invention is applied dissipates heat generated by an electronic component 3 such as a semiconductor element, and is fixed to a main surface 2a facing the electronic component 3 of a heat spreader 2 as shown in FIG. Then, it is sandwiched between the electronic component 3 and the heat spreader 2. Further, the heat conductive sheet is sandwiched between the heat spreader 2 and the heat sink 5.
- the heat conductive sheet and the heat spreader 2 constitute a heat radiating member 4 that radiates heat from the electronic component 3.
- the heat spreader 2 is formed in, for example, a rectangular plate shape, and has a main surface 2a facing the electronic component 3 and a side wall 2b erected along the outer periphery of the main surface 2a.
- a heat conductive sheet 1 is provided on a main surface 2a surrounded by a side wall 2b, and a heat sink 5 is provided on the other surface 2c opposite to the main surface 2a via the heat conductive sheet 1.
- the heat spreader 2 is formed using, for example, copper or aluminum having good thermal conductivity, for example, because the higher the thermal conductivity, the lower the thermal resistance and the more efficiently absorbs the heat of the electronic component 4 such as a semiconductor element. be able to.
- the electronic component 3 is a semiconductor element such as BGA, for example, and is mounted on the wiring board 6. Further, the heat spreader 2 also has the front end surface of the side wall 2b mounted on the wiring board 6, thereby enclosing the electronic component 3 at a predetermined distance by the side wall 2b.
- the heat conductive sheet 1 is bonded to the main surface 2 a of the heat spreader 2, thereby forming a heat radiating member 4 that absorbs heat generated by the semiconductor element and dissipates heat from the heat sink 5.
- Adhesion between the heat spreader 2 and the heat conductive sheet 1 can be performed by the adhesive force of the heat conductive sheet 1 itself described later, but an adhesive may be used as appropriate.
- the adhesive a well-known heat-dissipating resin or heat-dissipating adhesive film responsible for adhesion and heat conduction of the heat conductive sheet 1 to the heat spreader 2 can be used.
- the heat conductive sheet 1 has a sheet body 7 in which a heat conductive resin composition containing a binder resin and a carbon fiber 11 coated with an insulating film is cured, and the carbon exposed on the surface of the sheet body 7.
- the fiber 11 is not covered with the insulating film, and is covered with the uncured component 8 of the binder resin that has oozed out of the sheet body 7.
- the heat conductive sheet 1 is formed by curing a heat conductive resin composition containing a binder resin and carbon fibers 11 covered with an insulating film.
- the body 9 is cut into a sheet shape to obtain a sheet body 7 in which the carbon fibers 11 are exposed on the sheet surface, and then the sheet body 7 is pressed or left to stand on the surface of the sheet body 7 and the sheet body 7. It is manufactured by coating the exposed carbon fiber 11 with the uncured component 8 of the binder resin.
- the carbon fibers 11 exposed on the surface of the sheet body 7 are not covered with the insulating film 12. Details will be described later.
- the carbon fiber 11 constituting the heat conductive sheet 1 is for efficiently conducting heat from the electronic component 3 to the heat spreader 2. If the average diameter of the carbon fiber 11 is too small, there is a concern that the specific surface area becomes excessive and the viscosity of the resin composition when the heat conductive sheet 1 is formed becomes too high. Since it may be difficult, the average diameter of the carbon fibers 11 is preferably 5 ⁇ m to 12 ⁇ m. The average fiber length is preferably 30 ⁇ m to 300 ⁇ m. If the average fiber length of the carbon fiber 11 is less than 30 ⁇ m, the specific surface area becomes excessive and the viscosity of the heat conductive resin composition tends to be too high, and if it is larger than 300 ⁇ m, the compression of the heat conductive sheet 1 is inhibited. Tend.
- the carbon fiber 11 is selected according to characteristics such as mechanical properties, thermal properties, and electrical properties required for the heat conductive sheet 1.
- characteristics such as mechanical properties, thermal properties, and electrical properties required for the heat conductive sheet 1.
- pitch-based carbon fibers or carbon fibers obtained by graphitizing polybenzazole can be preferably used because they exhibit high elastic modulus, good thermal conductivity, high conductivity, radio wave shielding properties, low thermal expansion properties, and the like.
- the content of the carbon fiber 11 in the heat conductive sheet 1 is too small, the thermal conductivity tends to be low, and if it is too large, the viscosity tends to increase, so it is preferably 16% to 40% by volume.
- the surface of the carbon fiber 11 is covered with an insulating film 12.
- the insulating film 12 can be made of a material having excellent electrical insulation properties such as silicon oxide and boron nitride.
- Examples of the method for coating the carbon fiber 11 with the insulating film 12 include a sol-gel method, a liquid phase deposition method, and a polysiloxane method.
- the surface of the carbon fiber 11 may be oxidized by a vapor phase method, a chemical treatment method, an electrolytic method, or the like.
- the average thickness of the insulating film 12 observed by cross-sectional TEM observation be 50 nm or more and less than 100 nm.
- an insulating film 12 having an average thickness of less than 50 nm is to be formed, it is necessary to reduce the film treatment concentration, so that it takes a long time to form the film, resulting in a loss of productivity, and a reduction in batch throughput and an increase in waste liquid. .
- the coating treatment concentration is increased, it is difficult to control the thickness and productivity is impaired, and there is a possibility that the insulation performance is impaired, for example, the carbon fibers 11 are partially exposed.
- the insulating film 12 having an average thickness of 100 nm or more when the insulating film 12 having an average thickness of 100 nm or more is formed, fine-particle silica is formed in addition to the silica that contributes to the formation of the insulating film 12 covering the carbon fibers 11. For this reason, when the carbon fiber 11 covered with the insulating film 12 is mixed with the binder resin, the particulate silica is also mixed at the same time, leading to deterioration of the thermal resistance value.
- a method of adjusting the film treatment concentration and adjusting the film thickness by repeating a plurality of times is also conceivable, an increase in the number of coating treatments leads to a decrease in production efficiency and an increase in the amount of waste liquid, which is not preferable.
- thermally conductive filler such as a fibrous filler, a plate-like filler, a scaly filler, or a spherical filler can be used in combination as long as the effects of the present invention are not impaired.
- thermally conductive filler examples include metal (eg, nickel, iron, etc.), glass, ceramics (eg, oxide (eg, aluminum oxide, silicon dioxide, etc.), nitride (eg, boron nitride, aluminum nitride, etc.). And non-metallic inorganic fibers such as borides (for example, aluminum boride) and carbides (for example, silicon carbide)).
- a spherical filler (preferably spherical alumina or spherical aluminum nitride) having a diameter of 0.1 ⁇ m to 10 ⁇ m is used, and the carbon fiber 11 is made 100%.
- 50 parts by weight to 900 parts by weight are used in combination with respect to parts by weight.
- the binder resin holds the carbon fiber 11 and the appropriately added thermally conductive filler in the thermally conductive sheet 1 and has characteristics such as mechanical strength, heat resistance, and electrical properties required for the thermally conductive sheet 1. It is selected according to.
- a binder resin can be selected from thermoplastic resins, thermoplastic elastomers, and thermosetting resins.
- Thermoplastic resins include polyethylene, polypropylene, ethylene- ⁇ olefin copolymers such as ethylene-propylene copolymer, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, Fluoropolymers such as polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer Polymer (ABS) resin, polyphenylene-ether copolymer (PPE) resin, modified PPE resin, aliphatic polyamides, aromatic polyamides, polyimide, Polymethacrylates such
- thermoplastic elastomer examples include styrene-butadiene block copolymer or hydrogenated product thereof, styrene-isoprene block copolymer or hydrogenated product thereof, styrene-based thermoplastic elastomer, olefin-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer. Polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like.
- thermosetting resin examples include crosslinked rubber, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin and the like.
- crosslinked rubber examples include natural rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene rubber, Examples include chlorosulfonated polyethylene rubber, butyl rubber, halogenated butyl rubber, fluorine rubber, urethane rubber, and silicone rubber.
- the heat conductive resin composition can be prepared by uniformly mixing various additives and volatile solvents as necessary in addition to the fibrous filler and the binder resin.
- such a heat conductive sheet 1 is obtained by curing a resin molding 9 formed by curing a heat conductive resin composition containing carbon fibers 11 covered with an insulating film 12 in a binder resin.
- the sheet body 7 with the carbon fiber 11 exposed on the sheet surface is obtained by slicing the sheet body, and then the sheet body 7 is manufactured by pressing or leaving it.
- the thermal conductive sheet 1 can suppress a decrease in thermal conductivity due to the insulating film 12. Thereafter, the heat conductive sheet 1 is coated with the carbon fiber 11 from which the insulating film 12 has been removed by the uncured component 8 of the binder resin that has oozed out on the surface by pressing or leaving the sheet body 7. Both insulation and thermal conductivity can be achieved.
- the heat conductive sheet 1 when the heat conductive sheet 1 is pressed or left, the uncured component 8 of the binder resin oozes from the sheet body 7 over the entire surface, and the uncured component 8 causes the following (1) and (2). ) Is coated. (1) Surface of sheet body 7 (2) Carbon fiber 11 exposed on the surface of sheet body 7 Thereby, the heat conductive sheet 1 expresses slight adhesiveness (tackiness) on the sheet surface. Therefore, the heat conductive sheet 1 has improved followability and adhesion to the surfaces of the electronic component 3 and the heat spreader 2, and can reduce thermal resistance even in a low load region.
- the surface of the sheet body 7 is coated with the uncured component 8 of the binder resin, and the surface of the heat conductive sheet 1 is slightly adhered to the main surface 2a of the heat spreader 2, or an electronic component. 3 can be temporarily fixed to the upper surface 3a. Therefore, the heat conductive sheet 1 does not need to use a separate adhesive, and can realize labor saving and cost reduction of the manufacturing process.
- the coating of the surface of the sheet body 7 with the uncured component 8 and the coating of the carbon fiber 11 from which the insulating film 12 has been removed with the uncured component 8 are not necessarily embedded in the carbon fiber 11 from which the insulating film 12 has been removed.
- the thickness of the carbon fiber 11 from which the insulating film 12 is removed can be determined if the surface of the sheet body 7 and the carbon fiber 11 from which the insulating film 12 has been removed are coated. Is enough.
- the heat conductive sheet 1 can obtain desired fine adhesiveness (tackiness) by adjusting the component ratio of the main component and the curing agent of the binder resin of the heat conductive resin composition.
- the heat conductive sheet 1 is pressed or allowed to stand while maintaining the sheet shape, so that the uncured component 8 of the binder resin oozes out and covers the entire surface of the sheet body 7. Appropriate fine tackiness can be obtained for the entire sheet.
- the heat conductive sheet 1 is hardened by the binder resin and lacks flexibility, and the coating of the binder resin of the sheet body 7 with the uncured component 8 is insufficient. At least a part of the sheet main body 7 does not exhibit fine adhesion.
- the amount of the curing agent is less than this component ratio, the adhesiveness is excessively exhibited and the sheet shape cannot be maintained, and it becomes difficult to cut out the sheet from the molded body, thereby impairing the handleability.
- the heat conduction sheet 1 has a Shore OO hardness of 70 or less according to the measuring method of ASTM-D2240.
- the hardness of the heat conductive sheet 1 exceeds 70 in Shore OO hardness, the sheet body 7 cannot exhibit sufficient flexibility, and the followability and adhesion to the surface of the electronic component 3 and the heat spreader 2 are reduced. There is a risk of increasing thermal resistance.
- the minimum of the hardness of the heat conductive sheet 1 is not specifically limited.
- the volume resistivity of the heat conductive sheet 1 is preferably 1 ⁇ 10 6 ⁇ ⁇ cm or more. Thereby, even if the heat conductive sheet 1 comes into contact with peripheral circuit components, there is no fear of causing failure of the electronic device.
- Examples of the surface shape of the heat conductive sheet include the following examples.
- One is a mode in which the surface is smooth as shown in FIG.
- the surface of the uncured component 8 covering the carbon fiber 11 is smooth.
- the other is an aspect in which the surface has a convex portion derived from the carbon fiber 11 exposed on the surface of the sheet body 7 as shown in FIG.
- the surface of the uncured component 8 covering the carbon fiber 11 is not smooth and has a convex portion derived from the carbon fiber 11. 5 and 6, the insulating film 12 that covers the carbon fibers 11 is omitted.
- the heat conductive sheet 1 of the present invention can be produced by a production method having the following steps (A) to (D). Hereinafter, it demonstrates in detail for every process.
- the heat conductive resin composition for heat conductive sheet 1 formation is prepared by disperse
- a block-shaped resin molded body 9 is formed from the prepared thermally conductive resin composition by an extrusion molding method or a mold molding method.
- the extrusion molding method and the mold molding method are not particularly limited. Among various known extrusion molding methods and mold molding methods, the viscosity of the heat conductive resin composition, the characteristics required for the heat conductive sheet 1, and the like. Depending on the situation, it can be adopted as appropriate.
- the binder resin flows and follows the flow direction. Some carbon fibers 11 are oriented, but many are randomly oriented.
- the carbon fiber 11 tends to be easily oriented at the center with respect to the width direction of the extruded resin molded body 9.
- the carbon fiber 11 is likely to be randomly oriented in the peripheral portion with respect to the width direction of the resin molded body 9 due to the influence of the slit wall.
- the size and shape of the resin molded body 9 can be determined according to the required size of the heat conductive sheet 1. For example, there is a rectangular parallelepiped having a vertical size of 0.5 cm to 15 cm and a horizontal size of 0.5 cm to 15 cm. The length of the rectangular parallelepiped may be determined as necessary.
- the formed resin molding 9 is sliced into sheets. Thereby, the sheet body 7 is obtained.
- the carbon fibers 11 are exposed on the surface (sliced surface) of the sheet obtained by slicing.
- the insulating film 12 covering the carbon fiber 11 exposed on the sheet surface is removed (that is, the carbon fiber 11 exposed on the sheet surface is removed). And not covered with the insulating film 12). Therefore, the heat conductive sheet 1 can maintain a good heat conductivity over the thickness direction.
- the method of slicing is not particularly limited, and can be appropriately selected from known slicing apparatuses 13 (preferably an ultrasonic cutter or a planer) depending on the size and mechanical strength of the resin molded body 9.
- slicing direction of the resin molded body 9 when the molding method is an extrusion molding method, some of the molding direction is oriented in the extrusion direction, and therefore, 60 ° to 120 °, more preferably 70 ° to the extrusion direction.
- the direction is ⁇ 100 degrees.
- the direction is particularly preferably 90 degrees (vertical).
- the carbon fibers 11 exposed on the surface of the sheet body 7 are covered with a binder resin component.
- this method include the following methods. (1) By pressing the sheet main body 7, the carbon fiber 11 exposed from the surface of the sheet main body 7 and the surface of the sheet main body 7 is covered with the uncured component 8 of the binder resin that has oozed out of the sheet main body 7. (2) By leaving the sheet main body 7, the carbon fiber 11 exposed from the surface of the sheet main body 7 and the surface of the sheet main body 7 is covered with the uncured component 8 of the binder resin that has oozed out of the sheet main body 7.
- the slice surface of the obtained sheet body 7 is pressed.
- a pair of pressing devices including a flat plate and a press head having a flat surface can be used. Moreover, you may press with a pinch roll.
- the shape of the surface of the heat conductive sheet obtained varies depending on the pressing conditions.
- the obtained sheet body 7 is left to stand.
- the shape of the surface of the heat conductive sheet obtained varies depending on the standing time. For example, if left for a short time, a heat conductive sheet having a convex portion derived from the carbon fiber 11 whose surface is exposed on the surface of the sheet body 7 as shown in FIG. 6 is obtained. On the other hand, if left for a long time, a heat conductive sheet having a smooth surface as shown in FIG. 5 is obtained.
- the uncured component 8 of the binder resin oozes out from the sheet body 7, and the heat conductive sheet 1 having the surface of the sheet body 7 covered with the uncured component 8 is obtained (see FIG. 3B).
- the heat conductive sheet 1 the carbon fiber 11 (carbon fiber 11 which is not coat
- the heat conductive sheet 1 exhibits slight adhesiveness (tackiness) on the sheet surface. Therefore, the heat conductive sheet 1 can improve followability and adhesion to the surfaces of the electronic component 3 and the heat spreader 2 and can reduce thermal resistance.
- the surface of the sheet body 7 is coated with the uncured component 8 of the binder resin, and the surface of the heat conductive sheet 1 is slightly adhered to the main surface 2a of the heat spreader 2, or an electronic component. 3 can be temporarily fixed to the upper surface 3a. Therefore, the heat conductive sheet 1 does not need to use a separate adhesive, and can realize labor saving and cost reduction of the manufacturing process.
- the heat conductive sheet 1 loses the slight adhesiveness of the surface during handling, if the pressing is performed, the uncured component 8 of the binder resin exudes from the sheet body 7 again, and the uncured component 8 The surface is coated. Therefore, the heat conductive sheet 1 can be repaired even when the bonding position to the heat spreader 2 or the temporary fixing position to the electronic component 3 is shifted.
- the uncured component 8 of the binder resin oozes out from the entire surface of the sheet body 7, and the side surface as well as the front and back surfaces of the sheet body 7 are covered. Since the uncured component 8 of the binder resin has an insulating property, the heat conductive sheet 1 is provided with an insulating property on the side surface. Therefore, even when the heat conductive sheet 1 is sandwiched between the electronic component 3 and the heat spreader 2 and bulges out to the periphery and comes into contact with the conductive member disposed in the periphery, the semiconductor element or It is possible to prevent a short circuit between the heat sink and the conductive member.
- the heat conductive sheet 1 is compressed in the thickness direction by being pressed, and the frequency of contact between the carbon fibers 11 and the heat conductive fillers can be increased. Thereby, it becomes possible to reduce the thermal resistance of the heat conductive sheet 1. Moreover, the surface of the heat conductive sheet 1 is smoothed by being pressed.
- the thermal resistance tends to be the same as when not pressing, and if it is too high, the sheet tends to stretch, and therefore preferably 0.0098 MPa to 9.8 MPa, more preferably It is 0.049 MPa to 9.3 MPa.
- the heat conductive sheet 1 has a spacer 10 disposed on a mounting surface facing the press head and the sheet body 7 is pressed, so that a predetermined amount corresponding to the height of the spacer 10 is obtained.
- the sheet thickness can be formed as follows.
- the uncured component 8 of the binder resin in the sheet body 7 oozes out, and the oozing stops when the entire sheet surface is covered.
- the uncured component 8 of the binder resin oozes out according to the blending ratio of the binder resin component and the curing agent component in the binder resin, the pressing pressure, the sheet area, etc., and covers the entire surface of the sheet body 7. A sufficient time can be set as appropriate.
- the pressing step may be performed while heating using a press head with a built-in heater in order to further promote the effect of oozing out the uncured component 8 of the binder resin and covering the surface of the sheet body 7.
- the heating temperature is preferably higher than the glass transition temperature of the binder resin.
- a sample of the heat conductive sheet was formed by changing the component ratio of the binder component and the curing agent component of the heat conductive resin composition, and the presence or absence of the carbon fiber insulating coating by the insulating film.
- the presence or absence of tackiness, Shore OO hardness, compressive stress [N], initial sheet thickness [mm], thermal resistance (K ⁇ cm 2 / W), and volume resistivity [ ⁇ ⁇ cm] were measured and evaluated.
- the insulating film was formed on the carbon fiber used in each example by the following method.
- the first compound [300 g of pitch-based carbon fiber (heat conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd.) having an average fiber length of 100 ⁇ m and an average fiber diameter of 9 ⁇ m, 600 g of tetraethoxysilane, and 2700 g of ethanol] And mixed with a stirring blade.
- the 2nd compound (1050 mass% aqueous ammonia 1050g) was thrown into this over 5 minutes. Stirring was carried out for 3 hours with the time when the addition of the second formulation was completed as 0 minutes.
- suction filtration was performed using a vacuum pump, and the collected sample was transferred to a beaker, washed with water or ethanol, and then filtered again to collect the sample.
- the collected sample was dried at 100 ° C. for 2 hours and fired at 200 ° C. for 8 hours to obtain coated carbon fibers.
- Production Example 2 Insulating film treatment of carbon fiber
- an insulating film treatment of the carbon fiber was performed in the same manner as in Production Example 1 to obtain a coated carbon fiber.
- ⁇ Pitch-based carbon fiber thermoally conductive fiber, average fiber length 150 ⁇ m, average fiber diameter 9 ⁇ m, manufactured by Nippon Graphite Fiber Co., Ltd.
- Production Example 3 Insulating film treatment of carbon fiber
- an insulating film treatment of the carbon fiber was performed in the same manner as in Production Example 1 to obtain a coated carbon fiber.
- ⁇ Pitch-based carbon fiber thermoally conductive fiber, average fiber length 90 ⁇ m, average fiber diameter 9 ⁇ m, manufactured by Nippon Graphite Fiber Co., Ltd.
- Production Example 4 Insulating film treatment of carbon fiber
- an insulating film treatment of the carbon fiber was performed in the same manner as in Production Example 1 to obtain a coated carbon fiber.
- ⁇ Pitch-based carbon fiber thermoally conductive fiber, average fiber length 110 ⁇ m, average fiber diameter 9 ⁇ m, manufactured by Nippon Graphite Fiber Co., Ltd.
- the processing conditions are the same except that the average fiber length of the pitch-based carbon fibers is changed. Even under the same processing conditions, the thickness of the formed film was changed by changing the average fiber length of the pitch-based carbon fibers. Specifically, the thickness of the formed film became thinner as the average fiber length of the carbon fibers was longer.
- the average fiber length of the carbon fiber is one of the factors that change the thickness of the coating.
- thermal resistance values of the heat conductive sheet samples according to Examples 1 to 16 and Comparative Examples 1 to 6 were measured in a load range of 1.0 kgf / cm 2 by a method based on ASTM-D5470.
- Example 1 In Example 1, 20 parts by volume of alumina particles (thermal conductive particles: manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size: 4 ⁇ m) coupled to a two-component addition reaction type liquid silicone resin with a silane coupling agent, Coated carbon fiber obtained in Production Example 1 (average fiber length 100 ⁇ m, average fiber diameter 9 ⁇ m) 22 vol% and aluminum nitride coupled with a silane coupling agent (thermally conductive particles: manufactured by Tokuyama Corporation, average particle diameter) 1 ⁇ m) and 24 vol% were dispersed to prepare a silicone resin composition (thermally conductive resin composition).
- alumina particles thermal conductive particles: manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size: 4 ⁇ m
- Coated carbon fiber obtained in Production Example 1 (average fiber length 100 ⁇ m, average fiber diameter 9 ⁇ m) 22 vol% and aluminum nitride coupled with a silane coupling agent (thermally conductive particles: manufactured by To
- the two-component addition reaction type liquid silicone resin is a mixture of 50% by mass of silicone A solution and 50% by mass of silicone B solution.
- the silicone A liquid and the silicone B liquid used in the following examples and comparative examples are the same as the silicone A liquid and the silicone B liquid, respectively.
- the obtained silicone resin composition was extruded into a rectangular parallelepiped hollow mold (30 mm ⁇ 30 mm) having a PET film peeled on the inner wall to mold a silicone molded body.
- the obtained silicone molding was cured in an oven at 100 ° C. for 6 hours to obtain a silicone cured product.
- the obtained silicone cured product was cut with an ultrasonic cutter to obtain a molded body sheet having a thickness of about 2 mm.
- the slice speed of the ultrasonic cutter was 50 mm per second.
- the ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 ⁇ m.
- the obtained molded sheet was sandwiched between peeled PET films and then pressed with a 1.97 mm thick spacer, whereby the sheet surface was covered with an uncured component of the binder resin.
- Got. The pressing conditions were 3 min at 80 ° C. and 1 MPa setting.
- the coated carbon fiber had an insulating film thickness of 77 nm.
- the heat conductive sheet sample had a Shore OO hardness of 61, an initial sheet thickness of 1.998 mm, and a compressive stress of 900N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 1 had a thermal resistance of 1.00 [K ⁇ cm 2 / W] and a volume resistivity of 2.3 ⁇ 10 10 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 2 As a two-component addition reaction type liquid silicone resin, except that a mixture of 55% by mass of silicone A solution and 45% by mass of silicone B solution was used, the same conditions as in Example 1, A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 77 nm.
- the heat conductive sheet sample had a Shore OO hardness of 55, an initial sheet thickness of 2.031 mm, and a compressive stress of 700N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 2 had a thermal resistance of 0.95 [K ⁇ cm 2 / W] and a volume resistivity of 2.7 ⁇ 10 10 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 3 As a two-component addition reaction type liquid silicone resin, except that a mixture of 60% by mass of a silicone A solution and 40% by mass of a silicone B solution was used, the same conditions as in Example 1, A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 77 nm.
- the heat conductive sheet sample had a Shore OO hardness of 50, an initial sheet thickness of 2.005 mm, and a compressive stress of 450 N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 3 had a thermal resistance of 0.92 [K ⁇ cm 2 / W] and a volume resistivity of 3.6 ⁇ 10 10 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 4 As the two-component addition reaction type liquid silicone resin, except that a mixture of 65% by mass of silicone A solution and 35% by mass of silicone B solution was used, the same conditions as in Example 1, A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 77 nm.
- the heat conductive sheet sample had a Shore OO hardness of 42, an initial sheet thickness of 1.982 mm, and a compressive stress of 300N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 4 had a thermal resistance of 0.94 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 4.4 ⁇ 10 10 [ ⁇ ⁇ cm]. .
- Example 5 a heat conductive sheet sample was prepared under the same conditions as in Example 1 except that the coated carbon fiber (average fiber length 150 ⁇ m) obtained in Production Example 2 was used as the carbon fiber.
- the coated carbon fiber had an insulating film thickness of 55 nm.
- the heat conductive sheet sample had a Shore OO hardness of 70, an initial sheet thickness of 2.000 mm, and a compressive stress of 950 N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 5 had a thermal resistance of 0.91 [K ⁇ cm 2 / W] and a volume resistivity of 3.6 ⁇ 10 9 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 6 a heat conductive sheet sample was prepared under the same conditions as in Example 2 except that the coated carbon fiber (average fiber length 150 ⁇ m) obtained in Production Example 2 was used as the carbon fiber.
- the coated carbon fiber had an insulating film thickness of 55 nm.
- the heat conductive sheet sample had a Shore OO hardness of 58, an initial sheet thickness of 2.009 mm, and a compressive stress of 800N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 6 had a thermal resistance of 0.88 [K ⁇ cm 2 / W] and a volume resistivity of 4.7 ⁇ 10 9 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 7 a heat conductive sheet sample was prepared under the same conditions as in Example 3 except that the coated carbon fiber (average fiber length 150 ⁇ m) obtained in Production Example 2 was used as the carbon fiber.
- the coated carbon fiber had an insulating film thickness of 55 nm.
- the heat conductive sheet sample had a Shore OO hardness of 57, an initial sheet thickness of 1.991 mm, and a compressive stress of 550N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 7 had a thermal resistance of 0.86 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 6.7 ⁇ 10 9 [ ⁇ ⁇ cm]. .
- Example 8 a heat conductive sheet sample was prepared under the same conditions as in Example 4 except that the coated carbon fiber (average fiber length 150 ⁇ m) obtained in Production Example 2 was used as the carbon fiber.
- the coated carbon fiber had an insulating film thickness of 55 nm.
- the heat conductive sheet sample had a Shore OO hardness of 50, an initial sheet thickness of 2.016 mm, and a compressive stress of 350 N. Slight tackiness was developed on the sheet surface. Further, the heat conductive sheet sample according to Example 8 had a thermal resistance of 0.88 [K ⁇ cm 2 / W] and a volume resistivity of 8.2 ⁇ 10 9 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 9 In Example 9, 43 vol% of alumina particles (thermal conductive particles: manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 4 ⁇ m) coupled to a two-component addition reaction type liquid silicone resin with a silane coupling agent, 23 vol% of the coated carbon fiber (average fiber length 90 ⁇ m, average fiber diameter 9 ⁇ m) obtained in Production Example 3 was dispersed to prepare a silicone resin composition (thermally conductive resin composition).
- the two-component addition reaction type liquid silicone resin is a mixture of 50% by mass of silicone A solution and 50% by mass of silicone B solution.
- the obtained silicone resin composition was extruded into a rectangular parallelepiped hollow mold (30 mm ⁇ 30 mm) having a PET film peeled on the inner wall to mold a silicone molded body.
- the obtained silicone molding was cured in an oven at 100 ° C. for 6 hours to obtain a silicone cured product.
- the obtained silicone cured product was cut with an ultrasonic cutter to obtain a molded body sheet having a thickness of about 2 mm.
- the slice speed of the ultrasonic cutter was 50 mm per second.
- the ultrasonic vibration applied to the ultrasonic cutter had an oscillation frequency of 20.5 kHz and an amplitude of 60 ⁇ m.
- a spacer was inserted and pressed to obtain a heat conductive sheet sample in which the sheet surface was covered with an uncured component of the binder resin.
- the pressing conditions were 3 min at 80 ° C. and 1 MPa setting.
- the coated carbon fiber had an insulating film thickness of 95 nm.
- the heat conductive sheet sample had a Shore OO hardness of 59, an initial sheet thickness of 2.017 mm, and a compressive stress of 900N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 9 had a thermal resistance of 1.89 [K ⁇ cm 2 / W] and a volume resistivity of 1.2 ⁇ 10 10 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Example 10 As a two-component addition reaction type liquid silicone resin, except that a mixture of 55% by mass of a silicone A solution and 45% by mass of a silicone B solution was used, the same conditions as in Example 9, A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 95 nm.
- the heat conductive sheet sample had a Shore OO hardness of 53, an initial sheet thickness of 2.008 mm, and a compressive stress of 800N. Slight tackiness was developed on the sheet surface. Further, the heat conductive sheet sample according to Example 10 had a thermal resistance of 1.83 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 2.9 ⁇ 10 10 [ ⁇ ⁇ cm]. .
- Example 11 As a two-component addition reaction type liquid silicone resin, except that a mixture of 60% by mass of silicone A solution and 40% by mass of silicone B solution was used, the same conditions as in Example 9 A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 95 nm.
- the heat conductive sheet sample had a Shore OO hardness of 51, an initial sheet thickness of 1.982 mm, and a compressive stress of 500N. Slight tackiness was developed on the sheet surface. Further, the heat conductive sheet sample according to Example 11 had a thermal resistance of 1.79 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 4.2 ⁇ 10 10 [ ⁇ ⁇ cm]. .
- Example 12 As a two-component addition reaction type liquid silicone resin, except that a mixture of 65% by mass of a silicone A solution and 35% by mass of a silicone B solution was used, the same conditions as in Example 9, A heat conduction sheet sample was prepared.
- the coated carbon fiber had an insulating film thickness of 95 nm.
- the heat conductive sheet sample had a Shore OO hardness of 45, an initial sheet thickness of 1.996 mm, and a compressive stress of 250N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 12 had a thermal resistance of 1.85 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 5.5 ⁇ 10 10 [ ⁇ ⁇ cm]. .
- Example 13 a molded body sheet was prepared under the same conditions as in Example 3 except that the coated carbon fiber (average fiber length 110 ⁇ m) obtained in Production Example 4 was used.
- the obtained molded sheet was sandwiched between peeled PET films and then pressed with a 1.97 mm thick spacer, whereby the sheet surface was covered with an uncured component of the binder resin.
- the pressing conditions were set at 100 ° C. and 1 MPa for 30 sec. By increasing the temperature and shortening the press time, the sheet surface was coated with a component that did not contribute to the reaction while reflecting the shape of the heat conductive filler.
- the coated carbon fiber had an insulating film thickness of 65 nm.
- the heat conductive sheet sample had a Shore OO hardness of 52, an initial sheet thickness of 2.011 mm, and a compressive stress of 500N. Slight tackiness was developed on the sheet surface. Further, the heat conductive sheet sample according to Example 13 had a thermal resistance of 0.85 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 8.9 ⁇ 10 9 [ ⁇ ⁇ cm]. .
- Example 14 a molded body sheet was prepared under the same conditions as in Example 4 except that the coated carbon fiber (average fiber length 110 ⁇ m) obtained in Production Example 4 was used.
- the obtained molded sheet was sandwiched between peeled PET films and then pressed with a 1.97 mm thick spacer, whereby the sheet surface was covered with an uncured component of the binder resin.
- the pressing conditions were set at 100 ° C. and 1 MPa for 30 sec. By increasing the temperature and shortening the press time, the sheet surface was coated with a component that did not contribute to the reaction while reflecting the shape of the heat conductive filler.
- the coated carbon fiber had an insulating film thickness of 65 nm.
- the heat conductive sheet sample had a Shore OO hardness of 48, an initial sheet thickness of 1.978 mm, and a compressive stress of 330 N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 14 had a thermal resistance of 0.84 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 8.3 ⁇ 10 9 [ ⁇ ⁇ cm]. .
- Example 15 a molded body sheet was prepared under the same conditions as in Example 3 except that the coated carbon fiber (average fiber length 110 ⁇ m) obtained in Production Example 4 was used.
- the sheet was left for one day without pressing to obtain a heat conductive sheet sample in which the sheet surface was covered with an uncured component of the binder resin.
- the surface of the sheet was coated with a component that did not contribute to the reaction while reflecting the shape of the heat conductive filler.
- the coated carbon fiber had an insulating film thickness of 65 nm.
- the heat conductive sheet sample had a Shore OO hardness of 50, an initial sheet thickness of 2.023 mm, and a compressive stress of 400N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 15 had a thermal resistance of 0.88 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 100 V of 9.4 ⁇ 10 9 [ ⁇ ⁇ cm]. .
- Example 16 a molded body sheet was prepared under the same conditions as in Example 3 except that the coated carbon fiber (average fiber length 110 ⁇ m) obtained in Production Example 4 was used.
- the sheet was left for 1 week without pressing to obtain a heat conductive sheet sample in which the sheet surface was covered with an uncured component of the binder resin.
- the surface of the sheet was coated with a component that does not contribute to the reaction on the surface of the heat conductive sheet.
- the coated carbon fiber had an insulating film thickness of 65 nm.
- the heat conductive sheet sample had a Shore OO hardness of 49, an initial sheet thickness of 2.001 mm, and a compressive stress of 350 N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Example 16 had a thermal resistance of 0.90 [K ⁇ cm 2 / W] and a volume resistivity of 1.2 ⁇ 10 10 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Comparative Example 1 is the same as Example 1 except that pitch-based carbon fiber (thermal conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m) that has not been subjected to insulation coating treatment is used. Under the conditions, a heat conduction sheet sample was prepared.
- pitch-based carbon fiber thermo conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m
- the heat conductive sheet sample according to Comparative Example 1 had a Shore OO hardness of 72, an initial sheet thickness of 2.010 mm, and a compressive stress of 1000N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Comparative Example 1 had a thermal resistance of 0.88 [K ⁇ cm 2 / W] and a volume resistivity of 3.4 ⁇ 10 4 [ ⁇ ⁇ cm] at an applied voltage of 1 V. .
- Comparative Example 2 is the same as Example 2 except that pitch-based carbon fiber (thermal conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m) that has not been subjected to insulation coating treatment is used. Under the conditions, a heat conduction sheet sample was prepared.
- pitch-based carbon fiber thermo conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m
- the heat conductive sheet sample according to Comparative Example 2 had a Shore OO hardness of 63, an initial sheet thickness of 1.99 mm, and a compressive stress of 900N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Comparative Example 2 had a thermal resistance of 0.85 [K ⁇ cm 2 / W] and a volume resistivity of 3.6 ⁇ 10 4 [ ⁇ ⁇ cm] at an applied voltage of 1 V. .
- Comparative Example 3 is the same as Example 3 except that pitch-based carbon fiber (thermal conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m) that has not been subjected to an insulating coating treatment is used. Under the conditions, a heat conduction sheet sample was prepared.
- pitch-based carbon fiber thermo conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m
- the heat conductive sheet sample according to Comparative Example 3 had a Shore OO hardness of 59, an initial sheet thickness of 1.999 mm, and a compressive stress of 450 N. Slight tackiness was developed on the sheet surface. Further, the heat conductive sheet sample according to Comparative Example 3 had a thermal resistance of 0.84 [K ⁇ cm 2 / W] and a volume resistivity at an applied voltage of 1 V of 3.9 ⁇ 10 4 [ ⁇ ⁇ cm]. .
- Comparative Example 4 is the same as Example 4 except that pitch-based carbon fiber (thermal conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m) that has not been subjected to an insulating coating treatment is used. Under the conditions, a heat conduction sheet sample was prepared.
- pitch-based carbon fiber thermo conductive fiber: manufactured by Nippon Graphite Fiber Co., Ltd., average fiber length: 100 ⁇ m, average fiber diameter: 9 ⁇ m
- the heat conductive sheet sample according to Comparative Example 4 had a Shore OO hardness of 50, an initial sheet thickness of 2.005 mm, and a compressive stress of 300N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Comparative Example 4 had a thermal resistance of 0.87 [K ⁇ cm 2 / W] and a volume resistivity of 4.7 ⁇ 10 4 [ ⁇ ⁇ cm] at an applied voltage of 1 V. .
- Comparative Example 5 the heat conductive sheet obtained in Comparative Example 1 was coated with a mixture of 50% by mass of silicone A solution and 50% by mass of silicone B solution as a two-component addition reaction type liquid silicone resin. A heat conductive sheet sample was prepared.
- the heat conductive sheet sample according to Comparative Example 5 had a Shore OO hardness of 75, an initial sheet thickness of 2.030 mm, and a compressive stress of 1050 N. Slight tackiness was developed on the sheet surface.
- the heat conductive sheet sample according to Comparative Example 5 had a thermal resistance of 2.43 [K ⁇ cm 2 / W] and a volume resistivity of 1.0 ⁇ 10 12 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- Comparative Example 6 In Comparative Example 6, the same conditions as in Comparative Example 5 were used except that the two-component addition reaction type liquid silicone resin to be applied was a mixture of 45% by mass of silicone A solution and 55% by mass of silicone B solution. Thus, a heat conductive sheet sample was prepared.
- the heat conductive sheet sample according to Comparative Example 6 had a Shore OO hardness of 75, an initial sheet thickness of 2.015 mm, and a compressive stress of 1200 N. Slight tackiness was not expressed on the sheet surface.
- the heat conductive sheet sample according to Comparative Example 6 had a thermal resistance of 2.56 [K ⁇ cm 2 / W] and a volume resistivity of 8.1 ⁇ 10 11 [ ⁇ ⁇ cm] at an applied voltage of 100 V. .
- thermal adhesion sheet samples according to Examples 1 to 16 and Comparative Examples 1 to 6 were evaluated for slight adhesiveness.
- the evaluation of the slight adhesion was made by sandwiching a molded product sheet obtained by slicing the cured silicone products according to Examples 1 to 16 and Comparative Examples 1 to 6 with a PET film not subjected to release treatment, and then adding a thickness of 1.
- a 97 mm spacer was put in, pressed at 80 ° C. and a setting of 2.45 MPa for 3 min, and then cooled to room temperature to obtain a heat conductive sheet sample for evaluation of slight adhesion.
- the thermal resistance is 1.89 [K ⁇ cm 2 / W] at the maximum and the volume resistivity is 3.6 ⁇ at the minimum. It is 10 9 [ ⁇ ⁇ cm], and both thermal conductivity and insulation properties are generally achieved.
- the carbon fiber contained in the heat conductive sheet sample is coated with an insulating film with a thickness of 50 nm or more and less than 100 nm, so that the insulating film is formed with a desired film thickness and good volume resistivity.
- the generation of silica fine particles can be suppressed, and the decrease in thermal conductivity can be prevented.
- the carbon fibers exposed on the sheet surface are cut by the insulating film at the time of slicing to expose the carbon fibers, but are covered with the uncured component of the binder resin. Therefore, it has insulation with respect to surrounding members without impairing the thermal conductivity.
- heat conductive sheets having a smooth surface as shown in FIG. 5 were obtained.
- heat conductive sheets having protrusions derived from carbon fibers whose surfaces were exposed on the surface of the sheet main body as shown in FIG. 6 were obtained.
- coated silicone resin is as low as 45%, an uncured component does not remain sufficiently, and even if it presses, the whole surface of a sheet
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Abstract
Description
前記シート本体の表面に露出した前記炭素繊維は、前記絶縁皮膜により被覆されておらず、且つ前記バインダ樹脂の成分によって被覆されているものである。
前記成型体をシート状に切断し、シート本体を得る工程と、
前記シート本体の表面に露出した前記炭素繊維を、前記バインダ樹脂の成分で被覆する工程とを有し、
前記シート本体を得る工程において、前記シート本体の表面に露出する前記炭素繊維を被覆する前記絶縁皮膜が除去されるものである。
熱伝導シート1は、バインダ樹脂と、絶縁皮膜に被覆された炭素繊維11とを含有する熱伝導性樹脂組成物が硬化されたシート本体7を有し、前記シート本体7の表面に露出した炭素繊維11は、前記絶縁皮膜により被覆されておらず、前記シート本体7より滲み出た前記バインダ樹脂の未硬化成分8によって被覆されている。
図4に示すように、炭素繊維11は表面が絶縁皮膜12によって被覆されている。絶縁皮膜12は、例えば酸化ケイ素、窒化ホウ素等の優れた電気絶縁性を有する材料を用いることができる。また、絶縁皮膜12により炭素繊維11を被覆する方法としては、例えばゾルゲル法、液相堆積法、ポリシロキサン法等が挙げられる。なお、炭素繊維11と絶縁皮膜12との接着性を高めるために、炭素繊維11の表面を気相法、薬液処理法、電解法などによって酸化させてもよい。
なお、炭素繊維11の他に、本発明の効果を損なわない範囲で、繊維状フィラー、板状フィラー、鱗片状フィラー、球状フィラー等の熱伝導性フィラーを併用することができる。
バインダ樹脂は、炭素繊維11及び適宜添加された熱伝導性フィラーを熱伝導シート1内に保持するものであり、熱伝導シート1に要求される機械的強度、耐熱性、電気的性質等の特性に応じて選択される。このようなバインダ樹脂としては、熱可塑性樹脂、熱可塑性エラストマー、熱硬化性樹脂の中から選択することができる。
(1)シート本体7の表面
(2)シート本体7の表面に露出された炭素繊維11
これにより、熱伝導シート1は、シート表面に微粘着性(タック性)が発現する。したがって、熱伝導シート1は、電子部品3やヒートスプレッダ2の表面に対する追従性、密着性が向上し、低荷重領域においても熱抵抗を低減させることができる。
主剤:硬化剤=50:50~65:35(質量比)
とすることが好ましい。
一つは、図5に示すように、表面が平滑な態様である。この場合、炭素繊維11を被覆する未硬化成分8の表面が平滑である。
もう一つは、図6に示すように、表面が、シート本体7の表面に露出した炭素繊維11に由来する凸部を有する態様である。この場合、炭素繊維11を被覆する未硬化成分8の表面が平滑ではなく、炭素繊維11に由来する凸部を有している。
なお、図5及び図6においては、炭素繊維11を被覆する絶縁皮膜12を省略している。
本発明の熱伝導シート1は、以下の工程(A)~(D)を有する製造方法によって製造することができる。以下、工程毎に詳細に説明する。
まず、絶縁皮膜12によって被覆された炭素繊維11及び適宜添加される熱伝導性フィラーをバインダ樹脂に分散させることにより熱伝導シート1形成用の熱伝導性樹脂組成物を調製する。この調製は、炭素繊維11及び熱伝導性フィラーとバインダ樹脂と必要に応じて配合される各種添加剤や揮発性溶剤とを公知の手法により均一に混合することにより行うことができる。
次に、調製された熱伝導性樹脂組成物から、押出し成型法又は金型成型法によりブロック状の樹脂成型体9を形成する。
次に、形成された樹脂成型体9をシート状にスライスする。これによりシート本体7が得られる。このシート本体7は、スライスにより得られるシートの表面(スライス面)に炭素繊維11が露出する。このとき、樹脂成型体9とともに炭素繊維11もカットされることから、シート表面に露出された炭素繊維11を被覆する絶縁皮膜12が除去される(即ち、シート表面に露出された炭素繊維11は、絶縁皮膜12によって被覆されていない)。したがって、熱伝導シート1は厚さ方向に亘って良好な熱伝導率を維持することができる。
次いで、シート本体7の表面に露出した炭素繊維11を、バインダ樹脂の成分で被覆する。この方法としては、例えば、以下の方法が挙げられる。
(1)シート本体7をプレスすることにより、シート本体7より滲み出たバインダ樹脂の未硬化成分8によって、シート本体の7表面及びシート本体7の表面より露出する炭素繊維11を被覆する。
(2)シート本体7を放置することにより、シート本体7より滲み出たバインダ樹脂の未硬化成分8によって、シート本体7の表面及びシート本体7の表面より露出する炭素繊維11を被覆する。
得られたシート本体7のスライス面をプレスする。プレスの方法としては、平盤と表面が平坦なプレスヘッドとからなる一対のプレス装置を使用することができる。また、ピンチロールでプレスしてもよい。
プレスの条件によって、得られる熱伝導シートの表面の形状は異なる。
得られたシート本体7を放置する。放置時間によって、得られる熱伝導シートの表面の形状は異なる。
例えば、短時間の放置であれば、図6に示すような、表面がシート本体7の表面に露出した炭素繊維11に由来する凸部を有する熱伝導シートが得られる。
一方、長時間の放置であれば、図5に示すような、表面が平滑な熱伝導シートが得られる。
各実施例に用いた炭素繊維への絶縁被膜の形成は、以下の方法により行った。
樹脂容器(PE)に、第一配合物〔平均繊維長100μm、平均繊維径9μmのピッチ系炭素繊維(熱伝導性繊維:日本グラファイトファイバー株式会社製)300g、テトラエトキシシラン600g、及びエタノール2700g〕を投入し撹拌翼にて混合した。これに、第二配合物(10質量%アンモニア水1050g)を5分間かけて投入した。第二配合物の投入が完了した時点を0分として3時間攪拌を行った。攪拌終了後、真空ポンプを用いて吸引濾過を行い、回収したサンプルをビーカーに移し、水やエタノールで洗浄後、再度濾過を行い、サンプルを回収した。回収したサンプルを100℃で2時間乾燥し、200℃で8時間焼成を行い、被覆炭素繊維を得た。
製造例1において、ピッチ系炭素繊維を以下のピッチ系炭素繊維に代えた以外は、製造例1と同様にして、炭素繊維の絶縁皮膜処理を行い、被覆炭素繊維を得た。
・ピッチ系炭素繊維(熱伝導性繊維、平均繊維長150μm、平均繊維径9μm、日本グラファイトファイバー株式会社製)
製造例1において、ピッチ系炭素繊維を以下のピッチ系炭素繊維に代えた以外は、製造例1と同様にして、炭素繊維の絶縁皮膜処理を行い、被覆炭素繊維を得た。
・ピッチ系炭素繊維(熱伝導性繊維、平均繊維長90μm、平均繊維径9μm、日本グラファイトファイバー株式会社製)
製造例1において、ピッチ系炭素繊維を以下のピッチ系炭素繊維に代えた以外は、製造例1と同様にして、炭素繊維の絶縁皮膜処理を行い、被覆炭素繊維を得た。
・ピッチ系炭素繊維(熱伝導性繊維、平均繊維長110μm、平均繊維径9μm、日本グラファイトファイバー株式会社製)
実施例1~16、及び比較例1~6に係る各熱伝導シートサンプルについて、ASTM-D2240の測定方法によるショアOO硬度を測定した。
また、実施例1~16、及び比較例1~6に係るシート本体プレス後の熱伝導シートについて、引張圧縮試験機((株)エーアンドデー製、テンシロンRTG1225)を用いて、圧縮速度25.4mm/minで40%圧縮した際の最大圧縮応力を測定した。
また、実施例1~16、及び比較例1~6に係る各熱伝導シートサンプルについて、ASTM-D5470に準拠した方法で荷重1.0kgf/cm2の範囲で熱抵抗値を測定した。
また、実施例1~16、及び比較例1~6に係る各熱伝導シートサンプルについて、JIS K-6911に準拠した方法で、三菱化学アナリテック社製ハイレスタ(MCP-HT800)及びURSプローブを用いて、体積抵抗率を測定した。印加電圧は実施例1~16では100V、比較例1~4では1V、比較例5~6では100Vとした。
なお、比較例1~4において、印加電圧を1Vとするのは、実施例や、比較例5~6とは異なり、印加電圧が低くても測定が可能な為である。
実施例1では、2液性の付加反応型液状シリコーン樹脂に、シランカップリング剤でカップリング処理したアルミナ粒子(熱伝導性粒子:電気化学工業株式会社製、平均粒径4μm)20vol%と、製造例1で得られた被覆炭素繊維(平均繊維長100μm、平均繊維径9μm)22vol%と、シランカップリング剤でカップリング処理した窒化アルミ(熱伝導性粒子:株式会社トクヤマ製、平均粒径1μm)24vol%とを分散させて、シリコーン樹脂組成物(熱伝導性樹脂組成物)を調製した。
2液性の付加反応型液状シリコーン樹脂は、シリコーンA液50質量%、シリコーンB液50質量%の比率で混合したものである。なお、以下の実施例・比較例において用いたシリコーンA液、及びシリコーンB液は、前記シリコーンA液、及び前記シリコーンB液とそれぞれ同じものである。
得られたシリコーン樹脂組成物を、内壁に剥離処理したPETフィルムを貼った直方体状の中空金型(30mm×30mm)の中に押し出してシリコーン成型体を成型した。得られたシリコーン成型体をオーブンにて100℃で6時間硬化してシリコーン硬化物とした。得られたシリコーン硬化物を、超音波カッターで切断し、厚み約2mmの成型体シートを得た。超音波カッターのスライス速度は、毎秒50mmとした。また、超音波カッターに付与する超音波振動は、発振周波数を20.5kHzとし、振幅を60μmとした。
熱伝導シートサンプルは、ショアOO硬度が61、シートの初期厚みが1.998mm、圧縮応力が900Nであった。
シート表面には微粘着性が発現した。
また、実施例1に係る熱伝導シートサンプルは、熱抵抗が1.00[K・cm2/W]、印加電圧100Vにおける体積抵抗率が2.3×1010[Ω・cm]であった。
実施例2では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液55質量%と、シリコーンB液45質量%とを混合したものを用いた他は、実施例1と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が55、シートの初期厚みが2.031mm、圧縮応力が700Nであった。
シート表面には微粘着性が発現した。
また、実施例2に係る熱伝導シートサンプルは、熱抵抗が0.95[K・cm2/W]、印加電圧100Vにおける体積抵抗率が2.7×1010[Ω・cm]であった。
実施例3では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液60質量%と、シリコーンB液40質量%とを混合したものを用いた他は、実施例1と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が50、シートの初期厚みが2.005mm、圧縮応力が450Nであった。
シート表面には微粘着性が発現した。
また、実施例3に係る熱伝導シートサンプルは、熱抵抗が0.92[K・cm2/W]、印加電圧100Vにおける体積抵抗率が3.6×1010[Ω・cm]であった。
実施例4では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液65質量%と、シリコーンB液35質量%とを混合したものを用いた他は、実施例1と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が42、シートの初期厚みが1.982mm、圧縮応力が300Nであった。
シート表面には微粘着性が発現した。
また、実施例4に係る熱伝導シートサンプルは、熱抵抗が0.94[K・cm2/W]、印加電圧100Vにおける体積抵抗率が4.4×1010[Ω・cm]であった。
実施例5では、炭素繊維として、製造例2で得られた被覆炭素繊維(平均繊維長150μm)を用いた他は、実施例1と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が70、シートの初期厚みが2.000mm、圧縮応力が950Nであった。
シート表面には微粘着性が発現した。
また、実施例5に係る熱伝導シートサンプルは、熱抵抗が0.91[K・cm2/W]、印加電圧100Vにおける体積抵抗率が3.6×109[Ω・cm]であった。
実施例6では、炭素繊維として、製造例2で得られた被覆炭素繊維(平均繊維長150μm)を用いた他は、実施例2と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が58、シートの初期厚みが2.009mm、圧縮応力が800Nであった。
シート表面には微粘着性が発現した。
また、実施例6に係る熱伝導シートサンプルは、熱抵抗が0.88[K・cm2/W]、印加電圧100Vにおける体積抵抗率が4.7×109[Ω・cm]であった。
実施例7では、炭素繊維として、製造例2で得られた被覆炭素繊維(平均繊維長150μm)を用いた他は、実施例3と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が57、シートの初期厚みが1.991mm、圧縮応力が550Nであった。
シート表面には微粘着性が発現した。
また、実施例7に係る熱伝導シートサンプルは、熱抵抗が0.86[K・cm2/W]、印加電圧100Vにおける体積抵抗率が6.7×109[Ω・cm]であった。
実施例8では、炭素繊維として、製造例2で得られた被覆炭素繊維(平均繊維長150μm)を用いた他は、実施例4と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が50、シートの初期厚みが2.016mm、圧縮応力が350Nであった。
シート表面には微粘着性が発現した。
また、実施例8に係る熱伝導シートサンプルは、熱抵抗が0.88[K・cm2/W]、印加電圧100Vにおける体積抵抗率が8.2×109[Ω・cm]であった。
実施例9では、2液性の付加反応型液状シリコーン樹脂に、シランカップリング剤でカップリング処理したアルミナ粒子(熱伝導性粒子:電気化学工業株式会社製、平均粒径4μm)43vol%と、製造例3で得られた被覆炭素繊維(平均繊維長90μm、平均繊維径9μm)23vol%を分散させて、シリコーン樹脂組成物(熱伝導性樹脂組成物)を調製した。
2液性の付加反応型液状シリコーン樹脂は、シリコーンA液50質量%、シリコーンB液50質量%の比率で混合したものである。
得られたシリコーン樹脂組成物を、内壁に剥離処理したPETフィルムを貼った直方体状の中空金型(30mm×30mm)の中に押し出してシリコーン成型体を成型した。得られたシリコーン成型体をオーブンにて100℃で6時間硬化してシリコーン硬化物とした。得られたシリコーン硬化物を、超音波カッターで切断し、厚み約2mmの成型体シートを得た。超音波カッターのスライス速度は、毎秒50mmとした。また、超音波カッターに付与する超音波振動は、発振周波数を20.5kHzとし、振幅を60μmとした。
熱伝導シートサンプルは、ショアOO硬度が59、シートの初期厚みが2.017mm、圧縮応力が900Nであった。
シート表面には微粘着性が発現した。
また、実施例9に係る熱伝導シートサンプルは、熱抵抗が1.89[K・cm2/W]、印加電圧100Vにおける体積抵抗率が1.2×1010[Ω・cm]であった。
実施例10では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液55質量%と、シリコーンB液45質量%とを混合したものを用いた他は、実施例9と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が53、シートの初期厚みが2.008mm、圧縮応力が800Nであった。
シート表面には微粘着性が発現した。
また、実施例10に係る熱伝導シートサンプルは、熱抵抗が1.83[K・cm2/W]、印加電圧100Vにおける体積抵抗率が2.9×1010[Ω・cm]であった。
実施例11では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液60質量%と、シリコーンB液40質量%とを混合したものを用いた他は、実施例9と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が51、シートの初期厚みが1.982mm、圧縮応力が500Nであった。
シート表面には微粘着性が発現した。
また、実施例11に係る熱伝導シートサンプルは、熱抵抗が1.79[K・cm2/W]、印加電圧100Vにおける体積抵抗率が4.2×1010[Ω・cm]であった。
実施例12では、2液性の付加反応型液状シリコーン樹脂として、シリコーンA液65質量%と、シリコーンB液35質量%とを混合したものを用いた他は、実施例9と同じ条件で、熱伝導シートサンプルを作成した。
熱伝導シートサンプルは、ショアOO硬度が45、シートの初期厚みが1.996mm、圧縮応力が250Nであった。
シート表面には微粘着性が発現した。
また、実施例12に係る熱伝導シートサンプルは、熱抵抗が1.85[K・cm2/W]、印加電圧100Vにおける体積抵抗率が5.5×1010[Ω・cm]であった。
実施例13では、製造例4で得られた被覆炭素繊維(平均繊維長110μm)を用いた他は、実施例3と同じ条件で、成型体シートを作成した。
熱伝導シートサンプルは、ショアOO硬度が52、シートの初期厚みが2.011mm、圧縮応力が500Nであった。
シート表面には微粘着性が発現した。
また、実施例13に係る熱伝導シートサンプルは、熱抵抗が0.85[K・cm2/W]、印加電圧100Vにおける体積抵抗率が8.9×109[Ω・cm]であった。
実施例14では、製造例4で得られた被覆炭素繊維(平均繊維長110μm)を用いた他は、実施例4と同じ条件で、成型体シートを作成した。
熱伝導シートサンプルは、ショアOO硬度が48、シートの初期厚みが1.978mm、圧縮応力が330Nであった。
シート表面には微粘着性が発現した。
また、実施例14に係る熱伝導シートサンプルは、熱抵抗が0.84[K・cm2/W]、印加電圧100Vにおける体積抵抗率が8.3×109[Ω・cm]であった。
実施例15では、製造例4で得られた被覆炭素繊維(平均繊維長110μm)を用いた他は、実施例3と同じ条件で、成型体シートを作成した。
熱伝導シートサンプルは、ショアOO硬度が50、シートの初期厚みが2.023mm、圧縮応力が400Nであった。
シート表面には微粘着性が発現した。
また、実施例15に係る熱伝導シートサンプルは、熱抵抗が0.88[K・cm2/W]、印加電圧100Vにおける体積抵抗率が9.4×109[Ω・cm]であった。
実施例16では、製造例4で得られた被覆炭素繊維(平均繊維長110μm)を用いた他は、実施例3と同じ条件で、成型体シートを作成した。
熱伝導シートサンプルは、ショアOO硬度が49、シートの初期厚みが2.001mm、圧縮応力が350Nであった。
シート表面には微粘着性が発現した。
また、実施例16に係る熱伝導シートサンプルは、熱抵抗が0.90[K・cm2/W]、印加電圧100Vにおける体積抵抗率が1.2×1010[Ω・cm]であった。
比較例1では、絶縁皮膜処理を行っていないピッチ系炭素繊維(熱伝導性繊維:日本グラファイトファイバー株式会社製、平均繊維長100μm、平均繊維径9μm)を用いた他は、実施例1と同じ条件で、熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現した。
また、比較例1に係る熱伝導シートサンプルは、熱抵抗が0.88[K・cm2/W]、印加電圧1Vにおける体積抵抗率が3.4×104[Ω・cm]であった。
比較例2では、絶縁皮膜処理を行っていないピッチ系炭素繊維(熱伝導性繊維:日本グラファイトファイバー株式会社製、平均繊維長100μm、平均繊維径9μm)を用いた他は、実施例2と同じ条件で、熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現した。
また、比較例2に係る熱伝導シートサンプルは、熱抵抗が0.85[K・cm2/W]、印加電圧1Vにおける体積抵抗率が3.6×104[Ω・cm]であった。
比較例3では、絶縁皮膜処理を行っていないピッチ系炭素繊維(熱伝導性繊維:日本グラファイトファイバー株式会社製、平均繊維長100μm、平均繊維径9μm)を用いた他は、実施例3と同じ条件で、熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現した。
また、比較例3に係る熱伝導シートサンプルは、熱抵抗が0.84[K・cm2/W]、印加電圧1Vにおける体積抵抗率が3.9×104[Ω・cm]であった。
比較例4では、絶縁皮膜処理を行っていないピッチ系炭素繊維(熱伝導性繊維:日本グラファイトファイバー株式会社製、平均繊維長100μm、平均繊維径9μm)を用いた他は、実施例4と同じ条件で、熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現した。
また、比較例4に係る熱伝導シートサンプルは、熱抵抗が0.87[K・cm2/W]、印加電圧1Vにおける体積抵抗率が4.7×104[Ω・cm]であった。
比較例5では、比較例1で得られた熱伝導シートに2液性の付加反応型液状シリコーン樹脂として、シリコーンA液50質量%と、シリコーンB液50質量%とを混合したものを塗布して熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現した。
また、比較例5に係る熱伝導シートサンプルは、熱抵抗が2.43[K・cm2/W]、印加電圧100Vにおける体積抵抗率が1.0×1012[Ω・cm]であった。
比較例6では、塗布する2液性の付加反応型液状シリコーン樹脂として、シリコーンA液45質量%と、シリコーンB液55質量%とを混合したものを用いた他は、比較例5と同じ条件で、熱伝導シートサンプルを作成した。
シート表面には微粘着性が発現しなかった。
また、比較例6に係る熱伝導シートサンプルは、熱抵抗が2.56[K・cm2/W]、印加電圧100Vにおける体積抵抗率が8.1×1011[Ω・cm]であった。
また、実施例1~16及び比較例1~6に係る各熱伝導シートサンプルについて、微粘着性の評価を行った。微粘着性の評価は、実施例1~16及び比較例1~6に係るシリコーン硬化物をスライスして得られた成型体シートを剥離処理していないPETフィルムで挟んだ後、厚さ1.97mmのスペーサを入れて80℃、2.45MPa設定で、3minプレスした後、常温まで冷却することにより、微粘着性評価用熱伝導シートサンプルを得た。
〔評価基準〕
◎(最適):剥離力が0.05~0.25(N/cm)の範囲で振れた場合
○(良好):剥離力が0.02~0.05(N/cm)、0.20~0.30(N/cm)の範囲で振れた場合
△(普通):剥離力が0~0.04(N/cm)の範囲で振れた場合
×(不良):シートの一部でも微粘着性が発現しない箇所が認められた場合
なお、実施例1~12、16においては、図5に示すような、表面が平滑な熱伝導シートが得られた。実施例13~15では、図6に示すような、表面がシート本体の表面に露出した炭素繊維に由来する凸部を有する熱伝導シートが得られた。
2 ヒートスプレッダ
2a 主面
3 電子部品
3a 上面
4 放熱部材
5 ヒートシンク
6 配線基板
7 シート本体
8 未硬化成分
9 樹脂成型体
10 スペーサ
11 炭素繊維
12 絶縁皮膜
13 スライス装置
Claims (13)
- バインダ樹脂と、絶縁皮膜により被覆された炭素繊維とを含有する熱伝導性樹脂組成物が硬化されたシート本体を有し、
前記シート本体の表面に露出した前記炭素繊維は、前記絶縁皮膜により被覆されておらず、且つ前記バインダ樹脂の成分によって被覆されている熱伝導シート。 - 表面が、前記シート本体の表面に露出した前記炭素繊維に由来する凸部を有する請求項1に記載の熱伝導シート。
- 前記炭素繊維を被覆する前記絶縁皮膜は、酸化ケイ素であり、
断面TEM観察により観察される前記絶縁皮膜の平均厚さが50nm以上、100nm未満である請求項1又は2記載の熱伝導シート。 - ASTM-D2240の測定方法によるショアOO硬度が70以下である請求項1~3のいずれか1項に記載の熱伝導シート。
- 前記シート本体が、熱伝導性フィラーを含有する請求項1~4のいずれか1項に記載の熱伝導シート。
- 前記シート本体の表面が前記バインダ樹脂の未硬化成分で被覆されている請求項1~5のいずれか1項に記載の熱伝導シート。
- バインダ樹脂と、絶縁皮膜により被覆された炭素繊維とを含有する熱伝導性樹脂組成物を所定の形状に成型して硬化することにより、前記熱伝導性樹脂組成物の成型体を得る工程と、
前記成型体をシート状に切断し、シート本体を得る工程と、
前記シート本体の表面に露出した前記炭素繊維を、前記バインダ樹脂の成分で被覆する工程とを有し、
前記シート本体を得る工程において、前記シート本体の表面に露出する前記炭素繊維を被覆する前記絶縁皮膜が除去される熱伝導シートの製造方法。 - 前記被覆する工程が、前記シート本体をプレスすることにより、前記シート本体より滲み出た前記バインダ樹脂の未硬化成分によって、前記シート本体の表面及び前記シート本体の表面より露出する前記炭素繊維を被覆する工程である請求項7記載の熱伝導シートの製造方法。
- 前記被覆する工程が、前記シート本体を放置することにより、前記シート本体より滲み出た前記バインダ樹脂の未硬化成分によって、前記シート本体の表面及び前記シート本体の表面より露出する前記炭素繊維を被覆する工程である請求項7記載の熱伝導シートの製造方法。
- 中空状の型内に、前記熱伝導性樹脂組成物を押し出して充填し、前記熱伝導性樹脂組成物を熱硬化することにより、前記炭素繊維が、押し出し方向に対してランダムに配向されている前記成型体を得る請求項7~9のいずれか1項に記載の熱伝導シートの製造方法。
- 電子部品の発する熱を放熱するヒートスプレッダと、
前記ヒートスプレッダに配設され、前記ヒートスプレッダと前記電子部品との間に挟持される請求項1~6のいずれか1項に記載の熱伝導シートとを有する放熱部材。 - 半導体素子と、
前記半導体素子の発する熱を放熱するヒートスプレッダと、
前記ヒートスプレッダに配設され、前記ヒートスプレッダと前記半導体素子との間に挟持される請求項1~6のいずれか1項に記載の熱伝導シートとを有する半導体装置。 - ヒートシンクを備え、
前記ヒートスプレッダと前記ヒートシンクとの間に請求項1~6のいずれか1項に記載の熱伝導シートが挟持されている請求項12記載の半導体装置。
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