Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W40/00—Arrangements for thermal protection or thermal control
  • H10W40/20—Arrangements for cooling
  • H10W40/25—Arrangements for cooling characterised by their materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W40/00—Arrangements for thermal protection or thermal control
  • H10W40/10—Arrangements for heating
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W40/00—Arrangements for thermal protection or thermal control
  • H10W40/20—Arrangements for cooling
  • H10W40/25—Arrangements for cooling characterised by their materials
  • H10W40/251—Organics
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W40/00—Arrangements for thermal protection or thermal control
  • H10W40/20—Arrangements for cooling
  • H10W40/25—Arrangements for cooling characterised by their materials
  • H10W40/257—Arrangements for cooling characterised by their materials having a heterogeneous or anisotropic structure, e.g. powder or fibres in a matrix, wire mesh or porous structures
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W40/00—Arrangements for thermal protection or thermal control
  • H10W40/20—Arrangements for cooling
  • H10W40/25—Arrangements for cooling characterised by their materials
  • H10W40/258—Metallic materials

Definitions

• the present disclosure relates to a heat conductive sheet, a heat dissipation device, and a method for manufacturing a heat conductive sheet.
• a heat dissipation device is generally conveniently used, which dissipates heat by sandwiching thermal conductive grease or a heat conductive sheet between a heat generating body such as a semiconductor package and a heat dissipating body such as aluminum or copper.
• thermally conductive sheets are superior to thermally conductive grease in terms of workability when assembling a heat dissipation device.
• Resin sheets filled with thermally conductive fillers are also known as thermally conductive sheets.
• Various resin sheets have been proposed that are filled with thermally conductive fillers and have excellent thermal conductivity, in which highly thermally conductive inorganic particles are selected as the thermally conductive fillers, and the inorganic particles are oriented perpendicular to the sheet surface.
• thermally conductive sheets in which thermally conductive fillers (boron nitride) are oriented in a direction substantially perpendicular to the sheet surface (for example, see Patent Document 1), and carbon fibers dispersed in a gel-like substance are oriented in a direction perpendicular to the sheet surface.
• a thermally conductive sheet having an oriented structure has been proposed.
• Patent Documents 1 and 2 consider a method of suppressing thermal resistance by orienting thermally conductive fillers, carbon fibers, etc. in a direction perpendicular to the sheet surface. In order to cope with the increase in heat generation due to the higher performance and larger size of semiconductors, it is desired to further reduce the thermal resistance of thermally conductive sheets. Therefore, it is preferable to aim at lowering the thermal resistance by considering methods other than the orientation of the thermally conductive filler, carbon fiber, etc. contained in the thermally conductive sheet.
• An object of the present disclosure is to provide a thermally conductive sheet with low thermal resistance, a heat dissipation device equipped with the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
• ⁇ 1> Contains at least one type of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles, and rod-like particles, and in the case of the scale-like particles, in the plane direction, the ellipsoidal particles In the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction, and the long axis direction is oriented in the thickness direction, A thermally conductive sheet containing a metal component with a melting point of 200°C or less.
• ⁇ 3> The thermally conductive sheet according to ⁇ 1> or ⁇ 2>, wherein the metal component is located on at least a part of the main surface of the thermally conductive layer.
• ⁇ 4> The thermally conductive sheet according to any one of ⁇ 1> to ⁇ 3>, wherein the metal component has a melting point of 60° C. or higher.
• ⁇ 5> Any one of ⁇ 1> to ⁇ 4>, wherein the metal component contains at least one element selected from the group consisting of tin, bismuth, indium, zinc, lead, gallium, cadmium, thallium, and antimony. Thermal conductive sheet described in .
• ⁇ 6> Contains at least one type of graphite particle (A) selected from the group consisting of scale particles, ellipsoidal particles, and rod-shaped particles, and in the case of the scale particles, in the plane direction, the ellipsoidal particles In the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction, and in the case of the rod-shaped particles, the long axis direction is oriented in the thickness direction.
• the thermally conductive sheet is pressure-bonded between a heating element and a heat radiating element, measurement is performed at at least one of the interface between the heating element and the thermally conductive sheet and the interface between the heat radiating element and the thermally conductive sheet.
• ⁇ 7> Comprising a heating element, a heat radiating element, and the thermally conductive sheet according to any one of ⁇ 1> to ⁇ 5> disposed between the heating element and the heat radiating element,
• a metal region containing the metal component is located on at least a portion of at least one of the main surface located on the heat generating body side and the main surface located on the heat radiating body side.
• a method for manufacturing a thermally conductive sheet for manufacturing the thermally conductive sheet according to any one of ⁇ 1> to ⁇ 5> comprising: A method for manufacturing a thermally conductive sheet, comprising the steps of preparing a composition containing the graphite particles (A), and manufacturing a thermally conductive sheet containing the metal component using the composition.
• the step of producing the thermally conductive sheet includes the steps of forming the thermally conductive layer and attaching the metal component to at least a portion of the surface of the thermally conductive layer.
• a method for manufacturing a thermally conductive sheet. ⁇ 11> The method for producing a thermally conductive sheet according to ⁇ 9> or ⁇ 10>, wherein the composition prepared in the step of preparing the composition contains the graphite particles and the metal component.
• thermoly conductive sheet with low thermal resistance a heat dissipation device including the same, and a method for manufacturing a thermally conductive sheet that can manufacture a thermally conductive sheet with low thermal resistance.
• FIG. 1 is a schematic configuration diagram of a thermally conductive sheet in which particulate low-melting point metal components are located on the main surface of a thermally conductive layer, which is an embodiment of the present invention.
• FIG. 1 is a schematic configuration diagram of a thermally conductive sheet in which a particulate low-melting point metal component is located inside a thermally conductive layer, which is an embodiment of the present invention.
• 1 is a schematic configuration diagram of a thermally conductive sheet according to an embodiment of the present invention, in which a metal region containing a low melting point metal component is located on the main surface of a thermally conductive layer.
• FIG. 1 is a schematic cross-sectional view of a heat dissipation device according to an embodiment of the present invention, in which a heat generating body is a semiconductor chip and a heat dissipation body is a heat spreader.
• 2 is a diagram showing the state of the interface according to image analysis in Examples 1 to 4 and Comparative Example 1.
• FIG. 1 is a schematic cross-sectional view of a heat dissipation device according to an embodiment of the present invention, in which a heat generating body is a semiconductor chip and a heat dissipation body is a heat spreader.
• 2 is a diagram showing the state of the interface according to image analysis in Examples 1 to 4 and Comparative Example 1.
• each component may contain multiple types of corresponding substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
• each component may include a plurality of types of particles.
• the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.
• layer or film refers to the case where the layer or film is formed only in a part of the region, in addition to the case where the layer or film is formed in the entire region when observing the region where the layer or film is present. This also includes cases where it is formed.
• laminate refers to stacking layers, and two or more layers may be bonded, or two or more layers may be removable.
• the thermally conductive sheet of the present disclosure contains at least one type of graphite particle (A) selected from the group consisting of scaly particles, ellipsoidal particles, and rod-shaped particles (also simply referred to as "graphite particles (A)").
• graphite particles (A) also simply referred to as "graphite particles (A)"
• a thermally conductive layer in which the planar direction is oriented in the case of the scale-like particles, the long axis direction in the case of the ellipsoidal particles, and the long axis direction in the case of the rod-like particles is oriented in the thickness direction Contains a metal component with a melting point of 200°C or less (also referred to as a "low melting point metal component").
• the thermally conductive sheet of the present disclosure is considered to have excellent thermal conductivity in the thickness direction and exhibit low thermal resistance because it includes a thermally conductive layer in which graphite particles (A) are oriented in the thickness direction.
• the thermally conductive sheet is thought to exhibit lower thermal resistance by containing a low melting point metal component.
• the reason for this is assumed to be as follows. Note that the present disclosure is not limited to the following speculations. In a thermally conductive sheet in which graphite particles (A) are oriented in the thickness direction, there are irregularities on the surface that contacts the adherend, and most of the thermal resistance is caused by contact between the thermally conductive sheet and the thermally conductive sheet. It originates from the resistance (also referred to as "contact thermal resistance") caused by gaps caused by contact with adherends such as heating elements and heat radiating elements.
• the thermally conductive sheet of the present disclosure by using a low melting point metal component which is a metal component with a relatively low melting point, the thermally conductive sheet and an adherend such as a heat generating element or a heat radiating element are bonded by heat. Melting point metal component melts. Furthermore, by applying pressure, the molten low melting point metal component tends to be localized at the interface between the heat conductive sheet and the adherend, and the heat conductive sheet and the adherend are brought into close contact via the molten low melting point metal component. Can be done.
• a low melting point metal component which is a metal component with a relatively low melting point
• the gaps that occur when the thermally conductive sheet and the adherend are bonded under heat are filled with the molten low-melting point metal component, so the contact thermal resistance is significantly reduced.
• the thermally conductive sheet of the present disclosure includes at least graphite particles (A) and a low-melting point metal component, and may also include components described below as long as the effects of the present disclosure are achieved.
• materials used for the thermally conductive sheet of the present disclosure will be explained.
• the thermally conductive layer included in the thermally conductive sheet contains graphite particles (A). It is believed that the graphite particles (A) primarily function as a highly thermally conductive filler.
• the graphite particles (A) are at least one type selected from the group consisting of scaly particles, ellipsoidal particles, and rod-shaped particles.
• the graphite particles (A) are oriented in the plane direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the thickness direction in the case of rod-like particles. .
• the graphite particles (A) have six-membered ring planes in the crystal in the planar direction in the case of scale-like particles, in the long axis direction in the case of ellipsoidal particles, and in the long axis direction in the case of rod-like particles. is preferably oriented.
• the six-membered ring plane is a plane in which a six-membered ring is formed in a hexagonal crystal system, and means a (0001) crystal plane.
• the shape of the graphite particles (A) is more preferably scaly.
• thermal conductivity tends to be further improved. This can be considered, for example, because the scale-like graphite particles are more easily oriented in a predetermined direction in the heat conductive layer.
• the six-membered ring plane in the crystal of the graphite particle (A) is oriented in the plane direction of the scale-like particle, the long axis direction of the ellipsoidal particle, or the long axis direction of the rod-like particle can be determined by X-ray diffraction measurement. It can be confirmed. Specifically, the orientation direction of the six-membered ring plane in the crystal of the graphite particle (A) is confirmed by the following method.
• a sample sheet for measurement is prepared in which the in-plane direction of the scale-like particles, the long-axis direction of the ellipsoidal particles, or the long-axis direction of the rod-like particles of the graphite particles (A) are oriented along the in-plane direction of the sheet.
• the following method may be mentioned.
• a mixture of a resin and graphite particles (A) in an amount of 10% by volume or more based on the resin is formed into a sheet.
• the "resin” used here is not particularly limited as long as it is a material that does not exhibit peaks that interfere with X-ray diffraction and can be formed into a sheet.
• an amorphous resin having cohesive strength as a binder can be used, such as acrylic rubber, NBR (acrylonitrile butadiene rubber), and SIBS (styrene-isobutylene-styrene copolymer).
• a sheet of this mixture is pressed to a thickness of 1/10 or less of the original thickness, and a plurality of pressed sheets are laminated to form a laminate.
• the operation of crushing this laminate to 1/10 or less is repeated three or more times to obtain a sample sheet for measurement.
• the graphite particle (A) is a scale-like particle, the plane direction, if it is an ellipsoidal particle, the long axis direction, and if it is a rod-like particle, the long axis direction is , it is oriented along the surface direction of the sample sheet for measurement.
• the six-membered ring plane in the crystal of graphite particles (A) is oriented in the plane direction in the case of scale-like particles, in the major axis direction in the case of ellipsoidal particles, and in the longitudinal direction in the case of rod-shaped particles.
• X-ray diffraction measurements are performed under the following conditions.
• Device For example, Bruker AXS Co., Ltd. “D8DISCOVER” X-ray source: CuK ⁇ with a wavelength of 1.5406 nm, 40 kV, 40 mA Step (measurement step width): 0.01° Step time: 720sec
• the planar direction is oriented, in the case of ellipsoidal particles, the long axis direction is oriented, and in the case of rod-shaped particles, the long axis direction is oriented in the thickness direction of the thermally conductive layer.
• "" means the direction between the surface (principal surface) of the thermally conductive layer and the surface direction (principal surface) of the thermally conductive layer. It means that the angle formed (hereinafter also referred to as "orientation angle”) is 60° or more.
• the orientation angle is preferably 80° or more, more preferably 85° or more, and even more preferably 88° or more.
• the orientation angle is determined by observing the cross section of the thermally conductive layer with a SEM (scanning electron microscope), and for any 50 graphite particles (A), the orientation angle is determined by the in-plane direction in the case of scaly particles and the in-plane direction in the case of ellipsoidal particles. is the average value when measuring the angle (orientation angle) between the long axis direction, and in the case of rod-shaped particles, the long axis direction and the surface (principal surface) of the thermally conductive layer.
• the particle size of the graphite particles (A) is not particularly limited.
• the average particle diameter of the graphite particles (A), as a mass average particle diameter, is preferably 1/2 or more and not more than the average thickness of the heat conductive layer.
• the mass average particle diameter of the graphite particles (A) is 1/2 or more of the average thickness of the heat conductive layer, an efficient heat conduction path is formed in the heat conductive layer, and thermal conductivity tends to improve.
• the mass average particle diameter of the graphite particles (A) is less than or equal to the average thickness of the thermally conductive layer, protrusion of the graphite particles (A) from the surface of the thermally conductive layer is suppressed, and the adhesion of the surface of the thermally conductive layer is excellent. There is a tendency.
• thermoly conductive layer so that the plane direction is oriented in the case of scale-like particles, the long axis direction in the case of ellipsoidal particles, and the long axis direction in the case of rod-like particles is oriented in the thickness direction.
• the method described in JP-A No. 2008-280496 can be used.
• sheets are produced using the composition, the sheets are laminated to produce a laminate, and the side end surfaces of the laminate are aligned (for example, 0 with respect to the normal from the main surface of the laminate).
• a slicing method (hereinafter also referred to as "layered slicing method”) can be used.
• the particle size of the graphite particles (A) used as a raw material is preferably 1/2 or more of the average thickness of the thermally conductive layer as a mass average particle size, and the average thickness is You can exceed it.
• the reason why the particle size of the graphite particles (A) used as a raw material may exceed the average thickness of the thermally conductive layer is that, for example, even if the graphite particles (A) have a particle size that exceeds the average thickness of the thermally conductive layer, This is because the graphite particles (A) are sliced together to form the thermally conductive layer, and as a result, the graphite particles (A) do not protrude from the surface of the thermally conductive layer.
• the particle diameter of the graphite particles (A) used as a raw material is preferably 1 to 5 times, and 2 to 4 times, the average thickness of the thermally conductive layer as a mass average particle diameter. It is more preferable that When the mass average particle diameter of the graphite particles (A) is one or more times the average thickness of the heat conductive layer, a more efficient heat conduction path is formed and the heat conductivity is further improved. When the thickness is 5 times or less the average thickness of the thermally conductive layer, the area occupied by the graphite particles (A) on the surface portion can be prevented from becoming too large, and a decrease in adhesiveness can be suppressed.
• the mass average particle diameter (D50) of the graphite particles (A) is measured using a laser diffraction particle size distribution device (for example, Nikkiso Co., Ltd. "Microtrack series MT3300") adapted to the laser diffraction/scattering method, and the mass cumulative When the particle size distribution curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
• a laser diffraction particle size distribution device for example, Nikkiso Co., Ltd. "Microtrack series MT3300
• the thermally conductive layer may contain graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, such as spherical graphite particles, artificial graphite particles, exfoliated graphite particles, acid-treated graphite particles, expanded graphite particles, and carbon. It may also contain fiber flakes and the like.
• the graphite particles (A) are preferably scale-like particles, and from the viewpoint of having a high degree of crystallinity and easily obtaining scales with a large particle size, scale-like expanded graphite particles obtained by crushing expanded graphite in the form of a sheet are preferred. preferable.
• the content of graphite particles (A) in the thermally conductive layer is, for example, preferably from 15% to 50% by volume, from 20% to 45% by volume from the viewpoint of the balance between thermal conductivity and adhesion. It is more preferable that the amount is 25% to 40% by volume.
• the content of graphite particles (A) is 15% by volume or more, thermal conductivity tends to improve.
• the content of graphite particles (A) is 50% by volume or less, deterioration in tackiness and adhesiveness tends to be suppressed.
• the thermally conductive layer contains graphite particles other than scale particles, ellipsoidal particles, and rod-shaped particles, it is preferable that the content of the entire graphite particles is within the above range.
• the content rate (volume %) of graphite particles (A) is a value determined by the following formula.
• Content rate (volume %) of graphite particles (A) [(Aw/Ad)/ ⁇ (Aw/Ad)+(Xw/Xd) ⁇ ] ⁇ 100
• Aw Mass composition (mass%) of graphite particles (A)
• Xw mass composition of other arbitrary components (mass%)
• Ad Density of graphite particles (A) (In this disclosure, Ad is calculated as 2.1.)
• Xd Density of other arbitrary components
• the heat conductive sheet of the present disclosure includes a metal component (low melting point metal component) having a melting point of 200° C. or lower.
• the low melting point metal component may be in the form of particles.
• the thermally conductive sheet of the present disclosure may be a member before being heat-compressed with an adherend such as a heating element or a heat radiating element.
• the particulate low melting point metal component is in a molten state, so even if the low melting point metal component is not particulate, good.
• the particle size of the low melting point metal component is not particularly limited, and may be 0.5 ⁇ m to 60 ⁇ m, 1 ⁇ m to 30 ⁇ m, or 5 ⁇ m to 15 ⁇ m. You can.
• the particle diameter (D50) of the low-melting point metal component is measured using a laser diffraction particle size distribution device adapted to the laser diffraction/scattering method (for example, "Microtrack Series MT3300" manufactured by Nikkiso Co., Ltd.), and the mass cumulative particle size distribution is When the curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
• a laser diffraction particle size distribution device adapted to the laser diffraction/scattering method
• the mass cumulative particle size distribution is When the curve is drawn from the small particle size side, it corresponds to the particle size at which the mass accumulation is 50%.
• the arrangement of the low melting point metal component is not particularly limited, and for example, it may be placed on the surface of the thermally conductive layer, or may be contained inside the thermally conductive layer.
• a low melting point metal component is located on at least a portion of the main surface of the thermally conductive layer.
• the low melting point metal component When a low melting point metal component is located on at least a part of the main surface of the thermally conductive layer, the low melting point metal component may be arranged on the entire main surface, and a part of the main surface (for example, a heating element) may be disposed on the entire main surface. , a low melting point metal component may be disposed in a portion that comes into contact with an adherend such as a heat sink).
• the low melting point metal component When a low melting point metal component is located on at least a portion of the main surface of the thermally conductive layer, the low melting point metal component may be arranged on one main surface, and the low melting point metal component may be arranged on two main surfaces. may have been done.
• the melting point of the low melting point metal component is not particularly limited as long as it is 200 ° C. or lower, and is preferably 60 ° C. or higher from the viewpoint of suppressing melting of the low melting point metal component when the heat conductive sheet is used for heat dissipation purposes. From the viewpoint of more suitably reducing contact thermal resistance, the temperature is preferably 80°C to 180°C, more preferably 80°C to 160°C.
• the composition of the low melting point metal component is not limited as long as it contains a metal element.
• Metallic elements also include nonmetallic elements that can exhibit properties similar to those of metallic elements.
• the low melting point metal component preferably contains at least one element selected from the group consisting of tin, bismuth, indium, zinc, lead, gallium, cadmium, thallium, and antimony, for example.
• the low melting point metal component is preferably a low melting point solder having a melting point of 200°C or less, more preferably a low melting point lead-free solder having a melting point of 200°C or less.
• Specific examples of low melting point solders include Sn-Bi solder, Sn-In solder, Bi-In solder, Sn-Zn solder, Bi-Sn-In solder, Sn-Zn-Bi solder, and the like.
• the content of the low melting point metal component contained in the thermally conductive sheet is, for example, from the viewpoint of the balance between thermal conductivity and adhesion, from 0.1% by volume to 20% by volume based on the total amount of the thermally conductive sheet. It is preferably 0.5% to 15% by volume, and even more preferably 1% to 10% by volume.
• the content of the low melting point metal component contained in the heat conductive sheet refers to the total content of the low melting point metal component disposed on the surface of the heat conductive layer and the low melting point metal component contained inside the heat conductive layer. means rate.
• the thermally conductive layer included in the thermally conductive sheet of the present disclosure may contain a component that is liquid at 25° C. (hereinafter also referred to as “liquid component (B)").
• liquid at 25°C means a substance that exhibits fluidity and viscosity at 25°C, and has a viscosity, which is a measure of viscosity, of 0.0001 Pa ⁇ s to 1000 Pa ⁇ s at 25°C. .
• viscosity is defined as a value measured at 25° C. using a rheometer at a shear rate of 5.0 s ⁇ 1 . Specifically, “viscosity” is measured as shear viscosity at a temperature of 25° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0°).
• the viscosity of the liquid component (B) at 25° C. is preferably 0.001 Pa ⁇ s to 100 Pa ⁇ s, more preferably 0.01 Pa ⁇ s to 10 Pa ⁇ s.
• the liquid component (B) is not particularly limited as long as it is liquid at 25°C, and is preferably a high molecular compound (polymer).
• the liquid component (B) include polybutene, polyisoprene, polysulfide, acrylonitrile rubber, silicone rubber, hydrocarbon resin, terpene resin, and acrylic resin. Among these, from the viewpoint of heat resistance, it is preferable that the liquid component (B) contains polybutene.
• the liquid component (B) may be used alone or in combination of two or more.
• polybutene refers to a polymer obtained by polymerizing isobutene or normal butene. It also includes polymers obtained by copolymerizing isobutene and normal butene. As for the structure, it refers to a polymer having a structural unit represented by "-CH 2 --C(CH 3 ) 2 --" or "-CH 2 --CH(CH 2 CH 3 )-". It is also sometimes called polyisobutylene.
• the polybutene only needs to contain the above structure, and other structures are not particularly limited.
• polybutenes examples include butene homopolymers and copolymers of butene and other monomer components.
• copolymers with other monomer components examples include copolymers of isobutene and styrene or copolymers of isobutene and ethylene.
• the copolymer may be a random copolymer, a block copolymer, or a graft copolymer.
• polybutene examples include NOF Polybutene TM Emmawet (registered trademark) from NOF Corporation, Nisseki Polybutene from JXTG Energy Corporation, Tetrax from JXTG Energy Corporation, and Tetrax from JXTG Energy Corporation. Examples include “Himol” and “Polyisobutylene” manufactured by Tomoe Kogyo Co., Ltd.
• the liquid component (B) mainly functions as, for example, a stress reliever with excellent heat resistance and humidity resistance, and a tackifier.
• a hot melt agent (D) described below, it tends to be possible to further improve cohesive force and fluidity during heating.
• the content of the liquid component (B) in the thermally conductive layer is preferably 10% by volume to 55% by volume, from the viewpoint of further enhancing adhesive strength, adhesion, sheet strength, hydrolysis resistance, etc. % to 50% by volume, and even more preferably 20% to 50% by volume.
• the content of the liquid component (B) is 10% by volume or more, the tackiness and adhesiveness tend to be further improved.
• the content of the liquid component (B) is 55% by volume or less, reductions in sheet strength and thermal conductivity tend to be more effectively suppressed.
• the thermally conductive layer included in the thermally conductive sheet may contain an acrylic acid ester polymer (C). It is thought that the acrylic ester polymer (C) mainly functions as, for example, a tackifier and an elasticity-imparting agent that allows the thickness to be restored in order to follow warping.
• the acrylic ester polymer (C) has, for example, butyl acrylate, ethyl acrylate, acrylonitrile, acrylic acid, glycidyl methacrylate, 2-ethylhexyl acrylate, etc. as main raw material components, and if necessary, methyl acrylate, etc.
• An acrylic acid ester polymer (so-called acrylic rubber) copolymerized with is preferably used.
• the acrylic ester polymer (C) may be used alone or in combination of two or more.
• the weight average molecular weight of the acrylic ester polymer (C) is preferably 100,000 to 1,000,000, more preferably 250,000 to 700,000, and even more preferably 400,000 to 600. ,000. When the weight average molecular weight is 100,000 or more, the film tends to have excellent strength, and when it is 1,000,000 or less, it tends to have excellent flexibility.
• the weight average molecular weight can be measured by gel permeation chromatography using a standard polystyrene calibration curve.
• the glass transition temperature (Tg) of the acrylic ester polymer (C) is preferably 20°C or lower, more preferably -70°C to 0°C, even more preferably -50°C to -20°C. be. When the glass transition temperature is 20° C. or lower, flexibility and adhesiveness tend to be excellent.
• the glass transition temperature (Tg) can be calculated from tan ⁇ derived from dynamic viscoelasticity measurement by tension.
• the acrylic ester polymer (C) may be present in the entire thermally conductive layer by internal addition, or may be localized on the surface by coating or impregnating the surface. In particular, coating on one side or impregnating one side is preferable because strong tackiness can be imparted to only one side, resulting in a sheet with good handling properties.
• the content of the acrylic ester polymer (C) in the thermally conductive layer is preferably from 3% by volume to 25% by volume, more preferably from 5% to 20% by volume, and from 7% by volume. More preferably, it is 15% by volume.
• the heat conductive layer included in the heat conductive sheet may contain a hot melt agent (D).
• the hot melt agent (D) has the effect of improving the strength of the heat conductive layer and improving the fluidity during heating.
• hot melt agent (D) examples include aromatic petroleum resins, terpene phenol resins, and cyclopentadiene petroleum resins. Further, the hot melt agent (D) may be a hydrogenated aromatic petroleum resin or a hydrogenated terpene phenol resin. The hot melt agent (D) may be used alone or in combination of two or more.
• the hot melt agent (D) when polybutene is used as the liquid component (B), the hot melt agent (D) should contain at least one selected from the group consisting of hydrogenated aromatic petroleum resins and hydrogenated terpene phenol resins. is preferred. These hot melt agents (D) have high stability and excellent compatibility with polybutene, so when forming a thermally conductive layer, they can achieve better thermal conductivity, flexibility, and handling properties. There is a tendency.
• hydrogenated aromatic petroleum resins include, for example, “Alcon” by Arakawa Chemical Co., Ltd. and “Imarv” by Idemitsu Kosan Co., Ltd.
• examples of commercially available hydrogenated terpene phenol resins include “Clearon” manufactured by Yasuhara Chemical Co., Ltd.
• commercially available cyclopentadiene petroleum resins include, for example, “Quinton” manufactured by Nippon Zeon Co., Ltd. and “Marcarez” manufactured by Maruzen Petrochemical Co., Ltd.
• the hot melt agent (D) is solid at 25°C and preferably has a softening temperature of 40°C to 150°C.
• a thermoplastic resin is used as the hot melt agent (D)
• the softening fluidity during thermocompression bonding is improved, and as a result, the adhesion tends to be improved.
• the softening temperature is 40° C. or higher, the cohesive force can be maintained near room temperature, and as a result, the necessary sheet strength can be easily obtained and the sheet tends to be excellent in handleability.
• the softening temperature is 150° C. or less, the softening fluidity during thermocompression bonding increases, and as a result, the adhesion tends to improve.
• the softening temperature is more preferably 60°C to 120°C. Note that the softening temperature is measured by the ring and ball method (JIS K 2207:1996).
• the content of the hot melt agent (D) in the thermally conductive layer is preferably 3% to 25% by volume, and preferably 5% to 20% by volume from the viewpoint of increasing adhesive strength, adhesion, sheet strength, etc. It is more preferable that the amount is 5% by volume to 15% by volume.
• adhesive strength, heat fluidity, sheet strength, etc. tend to be sufficient, and when the content is 25% by volume or less, flexibility is insufficient. They tend to have excellent handling properties and thermal cycle resistance.
• the thermally conductive layer included in the thermally conductive sheet may contain an antioxidant (E), for example, for the purpose of imparting thermal stability at high temperatures.
• examples of the antioxidant (E) include phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, hydrazine antioxidants, and amide antioxidants.
• the antioxidant (E) may be appropriately selected depending on the temperature conditions used, etc., and phenolic antioxidants are more preferred.
• the antioxidant (E) may be used alone or in combination of two or more.
• phenolic antioxidants include, for example, ADEKA STAB AO-50, ADEKA STAB AO-60, and ADEKA STAB AO-80 manufactured by ADEKA Corporation.
• the content of the antioxidant (E) in the thermally conductive layer is not particularly limited, and is preferably 0.1% to 5% by volume, more preferably 0.2% to 3% by volume. It is preferably 0.3% by volume to 1% by volume or less. When the content of the antioxidant (E) is 0.1% by volume or more, a sufficient antioxidant effect tends to be obtained. When the content of the antioxidant (E) is 5% by volume or less, the strength of the heat conductive layer tends to be prevented from decreasing.
• the thermally conductive layer contained in the thermally conductive sheet includes graphite particles (A), a low melting point metal component, a liquid component (B), an acrylic ester polymer (C), a hot melt agent (D), and an antioxidant ( Components other than E) may be contained depending on the purpose.
• the heat conductive layer may contain a flame retardant from the viewpoint of flame retardancy.
• the flame retardant is not particularly limited and can be appropriately selected from commonly used flame retardants. Examples include red phosphorus flame retardants and phosphate ester flame retardants. Among these, phosphoric acid ester flame retardants are preferred from the viewpoint of excellent safety and improved adhesion due to the plasticizing effect.
• red phosphorus flame retardant in addition to pure red phosphorus particles, those coated with various coatings for the purpose of increasing safety or stability, those made into masterbatches, etc. may be used. Specific examples include Nobared, Nova Excel, Novaquel, and Nova Pellet (all trade names) manufactured by Rin Kagaku Kogyo Co., Ltd.
• Phosphate ester flame retardants include aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, and tributyl phosphate; triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tricylenyl phosphate, and cresyl di-2,6-oxy Aromatic phosphate esters such as renyl phosphate, tris (t-butylated phenyl) phosphate, tris (isopropylated phenyl) phosphate, triaryl isopropylated phosphate; resorcinol bisdiphenyl phosphate, bisphenol A bis (diphenyl phosphate), resorcinol Examples include aromatic condensed phosphoric acid esters such as bisdixylenyl phosphate. Among these, bisphenol A bis(diphenyl phosphate) is preferable from the viewpoints of excellent hydrolysis resistance
• the content of the flame retardant in the heat conductive layer is not limited and can be used in an amount that exhibits flame retardancy, and is preferably about 30% by volume or less. From the viewpoint of suppressing deterioration of thermal resistance due to seepage, the content is preferably 20% by volume or less.
• the average thickness of the thermally conductive sheet is not particularly limited and can be appropriately selected depending on the purpose.
• the thickness of the thermally conductive sheet can be appropriately selected depending on the specifications of the semiconductor package used. As the thickness decreases, the thermal resistance tends to decrease, and as the thickness increases, the warp followability tends to improve.
• the average thickness of the thermally conductive sheet may be 50 ⁇ m to 3000 ⁇ m, preferably 100 ⁇ m to 500 ⁇ m, more preferably 100 ⁇ m to 300 ⁇ m from the viewpoint of thermal conductivity and adhesion.
• the average thickness of the thermally conductive sheet is given as the arithmetic mean value of three thicknesses measured at random using a micrometer.
• the thermally conductive sheet may have a protective film on at least one side, and preferably has a protective film on both sides. Thereby, the adhesive surface of the heat conductive sheet can be protected.
• the protective film for example, resin films such as polyethylene, polyester, polypropylene, polyethylene terephthalate, polyimide, polyetherimide, polyether naphthalate, and methylpentene, coated paper, coated cloth, and metal foils such as aluminum can be used. These protective films may be used alone or in combination of two or more to form a multilayer film.
• the protective film is preferably surface-treated with a silicone-based, silica-based, or the like release agent.
• thermally conductive sheet is not particularly limited.
• the thermally conductive sheet of the present disclosure is particularly suitable as a thermally conductive sheet (TIM1; Thermal Interface Material 1) interposed between the semiconductor chip and the heat spreader when the semiconductor chip is used as the heat generating body and the heat spreader is used as the heat radiating body.
• TIM1 Thermal Interface Material 1
• Embodiments of the thermally conductive sheet will be described using FIGS. 1 to 3.
• the thermally conductive sheet of the present disclosure is not limited to the following embodiments.
• Component 12C is located in the thermally conductive sheet 1A shown in FIG.
• a particulate low melting point metal component 12B is contained inside the thermally conductive layer 11.
• a metal region 13A containing a low melting point metal component is located on one main surface of the thermally conductive layer 11, and a particulate low melting point metal component is located on the other main surface of the thermally conductive layer 11.
• a metal region 13C containing a metal component is located.
• a modified example of the thermally conductive sheet of the present disclosure contains at least one type of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoid-like particles, and rod-like particles, and in the case of the scale-like particles, between the heating element and the heat dissipating element, comprising a thermally conductive layer oriented in the plane direction, in the major axis direction in the case of the ellipsoidal particles, and in the thickness direction in the case of the rod-shaped particles;
• A graphite particle selected from the group consisting of scale-like particles, ellipsoid-like particles, and rod-like particles, and in the case of the scale-like particles, between the heating element and the heat dissipating element, comprising a thermally conductive layer oriented in the plane direction, in the major axis direction in the case of the ellipsoidal particles, and in the thickness direction in the case of the rod-shaped particles;
• the thermally conductive sheet is pressure-bonded between a heating element and a heat radiating element, for example, when used as a heat radiating device described below, the above-mentioned porosity is 0% to 8%.
• gaps that occur when heat-compression bonding the thermally conductive sheet and the heat generating element or the heat dissipating element are removed by melting. Since it is filled with a melting point metal component, the contact thermal resistance is significantly reduced.
• the above-mentioned porosity is preferably 0% to 6%, more preferably 0% to 4%, from the viewpoint of further reducing contact thermal resistance.
• the modified example of the heat conductive sheet of the present disclosure and the above-described heat conductive sheet of the present disclosure and its preferred form may be combined as appropriate.
• the thermally conductive sheet according to the modified example may further include a metal component having a melting point of 200° C. or lower.
• the method for manufacturing the thermally conductive sheet is not particularly limited as long as it can produce a thermally conductive sheet having the above configuration.
• Examples of methods for manufacturing the thermally conductive sheet include the following methods.
• the method for producing a thermally conductive sheet includes a step of preparing a composition containing graphite particles (A) and optional other components (also referred to as a "preparation step"), and a step of preparing a composition containing graphite particles (A) and optional other components;
• the method includes a step (also referred to as a "manufacturing step") of manufacturing a thermally conductive sheet containing a melting point metal component.
• the method of incorporating the low-melting point metal component into the thermally conductive sheet is not particularly limited. Method 2, etc., in which a low melting point metal component is attached to at least a part of the surface, etc. can be mentioned.
• the composition prepared in the above-mentioned preparation step may contain graphite particles (A), a low melting point metal component, and any other components.
• the composition may be prepared by mixing the graphite particles (A), the low melting point metal component, and any other components.
• the step of producing the thermally conductive sheet may include a step of forming the thermally conductive layer (also referred to as a "forming step").
• the step of producing a thermally conductive sheet includes a step of forming the thermally conductive layer (also referred to as a "forming step"), and attaching a low melting point metal component to at least a portion of the surface of the thermally conductive layer. (also referred to as an "attachment step").
• the forming steps in Method 1 and Method 2 include a step of forming the composition prepared in the preparation step into a sheet to obtain a sheet (also referred to as a "sheet producing step"), and a step of producing a laminate of the sheets (also referred to as a "laminate”).
• the method preferably includes a step of slicing the side end surface of the laminate (also referred to as a "slicing step").
• a thermally conductive sheet containing a low melting point metal component is obtained through the above-mentioned slicing process. If necessary, after obtaining a heat conductive sheet containing a low melting point metal component, a low melting point metal component may be attached to at least a portion of the surface of the heat conductive layer (that is, method 1 and method 2 may be used in combination) ).
• Method 2 it is preferable to perform a step of attaching a low-melting point metal component to at least a portion of the surface of the thermally conductive layer obtained in the slicing step (also referred to as an "attachment step"). By passing through the adhesion process, a thermally conductive sheet containing a low melting point metal component can be manufactured.
• the method for manufacturing a thermally conductive sheet involves a process of pasting and laminating the sliced sheet obtained in the slicing process (or a thermally conductive sheet containing a low melting point metal component if it includes an adhesion process) onto a protective film (a process called the "laminate process"). ) may also be included.
• thermally conductive sheet By manufacturing a thermally conductive sheet using such a method, an efficient thermally conductive path is likely to be formed, and therefore a thermally conductive sheet with high thermal conductivity and excellent adhesion tends to be obtained.
• ⁇ Preparation process> In the preparation step, graphite particles (A) and any other components (for example, a low melting point metal component, a component (B) that is liquid at 25 ° C., an acrylic ester polymer (C), a hot melt agent (D), A composition containing an antioxidant (E) and other components) is prepared.
• the method for blending each component is not particularly limited, and any method may be used as long as each component can be mixed uniformly.
• the composition may be prepared by obtaining a commercially available composition. For details on the preparation of the composition, reference can be made to paragraph [0033] of JP-A-2008-280496.
• the sheet production step is not particularly limited and may be performed by any method as long as the composition obtained in the previous step can be formed into a sheet.
• at least one molding method selected from the group consisting of rolling, pressing, extrusion, and coating.
• a laminate of sheets obtained in the previous step is formed.
• the laminate may be produced by sequentially stacking a plurality of independent sheets, may be produced by folding a single sheet, or may be produced by winding one of the sheets. .
• the laminate manufacturing process reference can be made to paragraphs [0035] to [0037] of JP-A-2008-280496.
• the slicing step is not particularly limited and may be any method as long as it can slice the side end surface of the laminate obtained in the previous step.
• the graphite particles (A) that penetrate in the thickness direction of the heat conductive layer form an extremely efficient heat conduction path, and from the viewpoint of further improving thermal conductivity, the mass average particle diameter of the graphite particles (A) is twice or less. It is preferable to slice with a thickness of .
• JP-A-2008-280496 for details of the slicing process, reference can be made to paragraph [0038] of JP-A-2008-280496.
• the attachment step is not particularly limited and may be any method as long as the low melting point metal component can be attached to at least a portion of the surface of the thermally conductive layer obtained in the slicing step.
• metal particles having a melting point of 200° C. or lower may be sprinkled on at least a portion of the surface of the thermally conductive layer, or a low melting point metal component may be attached by a method such as coating, vapor deposition, or sputtering.
• the lamination process may be any method as long as the sliced sheet obtained in the slicing process (or a thermally conductive sheet containing a low-melting metal component if an adhesion process is included) can be attached to the protective film, and in particular, Not limited.
• the heat dissipation device of the present disclosure includes a heat generating body, a heat dissipating body, and a heat conductive sheet of the present disclosure disposed between the heat generating body and the heat dissipating body, and the heat conductive layer is located on the side of the heat generating body.
• a metal region containing a low melting point metal component is located on at least a portion of at least one of the main surface and the main surface located on the side of the heat sink. It is preferable that a metal region is located on at least a part of the main surface located on the heating element side and at least a part of the main surface located on the heat radiating element side. It is more preferable that the metal regions are respectively located in regions facing the heat radiator on the main surface located on the body side.
• the metal region containing the low melting point metal component may be layered or may be dotted on the main surface of the thermally conductive sheet.
• the above-mentioned metal region only needs to be located on at least a part of the main surface of the heat conductive sheet, and may be further contained inside the heat conductive sheet.
• heating elements include semiconductor chips, semiconductor packages, power modules, etc.
• heat radiator examples include a heat spreader, a heat sink, a water cooling pipe, and the like.
• the maximum thickness of the metal region may be 3 ⁇ m to 20 ⁇ m on one side, or 5 ⁇ m to 15 ⁇ m from the viewpoint of reducing contact thermal resistance and thermal conductivity.
• the maximum thickness is 20 ⁇ m or less, it tends to be possible to suppress an increase in bulk thermal resistance corresponding to the thermal conductivity of the metal itself.
• the maximum thickness is 3 ⁇ m or more, the effect of filling the gap created when heat-compression bonding the heat conductive sheet and the adherend is bonded is sufficiently obtained, and the contact thermal resistance tends to be reduced more suitably.
• the maximum thickness of the thermally conductive layer and the maximum thickness of the metal region may be measured by observing the cross section of the measurement target using an electron microscope.
• the maximum thickness of the thermally conductive layer may be measured using a micrometer, and the maximum thickness of the thermally conductive layer and the maximum thickness of the thermally conductive sheet including the metal region are measured, and the maximum thickness of the thermally conductive sheet is The maximum thickness of the metal region may be determined by subtracting the maximum thickness of the conductive layer.
• a heat radiating device using a semiconductor chip as a heat generating body and a heat spreader as a heat radiating body will be described.
• a semiconductor chip and a heat spreader are examples of a heat generating body and a heat radiating body, respectively, and the present disclosure is not limited thereto.
• a thermally conductive sheet 1 is used with one surface in close contact with a semiconductor chip 2 and the other surface in close contact with a heat spreader 3 (heat radiator).
• the semiconductor chip 2 is fixed to the substrate 4 using an underfill material 5, and the heat spreader 3 is fixed to the substrate 4 by a sealing material 6, which presses the adhesion between the thermally conductive sheet 1, the semiconductor chip 2, and the heat spreader 3. This is what makes it better.
• a heating element and one heat radiating element are provided for one heat conductive sheet 1.
• a plurality of semiconductor chips 2 may be provided for one heat conductive sheet 1
• one semiconductor chip 2 may be provided for a plurality of heat conductive sheets 1
• a plurality of semiconductor chips 2 may be provided for a plurality of heat conductive sheets 1.
• a plurality of semiconductor chips 2 may be provided on the heat conductive sheet 1.
• a metal region containing a low melting point metal component is located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side and on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side.
• the metal regions 13A and 13C are located on the main surface of the thermally conductive sheet 1 on the semiconductor chip 2 side and on the main surface of the thermally conductive sheet 1 on the heat spreader 3 side, respectively. Good too. Further, the metal region 13A may be in contact with the heat spreader 3, and the metal region 13C may be in contact with the semiconductor chip 2.
• the heat radiating device includes the heat conductive sheet of the present disclosure disposed between a heat generating element and a heat radiating element. Since the heating element and the heat radiating element are laminated via the heat conductive sheet, heat from the heating element can be efficiently conducted to the heat radiating element. By being able to conduct heat efficiently, the lifespan of the heat dissipation device is improved, and a heat dissipation device that functions stably even during long-term use can be provided.
• the temperature range in which the thermally conductive sheet can be particularly preferably used may be, for example, -40°C to 150°C, -10°C to 100°C, or -10°C to 80°C. .
• suitable examples of the heating element include semiconductor packages, displays, LEDs, electric lights, automotive power modules, and industrial power modules.
• the heat sink examples include a heat sink using aluminum or copper fins or plates, an aluminum or copper block connected to a heat pipe, an aluminum or copper block in which a cooling liquid is circulated by a pump, and a Peltier element and an aluminum or copper block equipped with the same.
• the heat radiating device is constructed by bringing each surface of a heat conductive sheet into contact with a heat generating element and a heat radiating element.
• the method of bringing the heating element into contact with one side of the heat conductive sheet and the method of bringing the heat radiating element into contact with the other side of the heat conductive sheet are especially suitable as long as they can be fixed in a sufficiently close state. Not restricted.
• a heat conductive sheet may be placed between the heating element and the heat radiating element, fixed with a jig that can be pressurized to approximately 0.05 MPa to 1 MPa, and the heating element may be heated in this state, or the Examples include a method of heating to about .degree. C. to 200.degree. C. (for example, at a temperature equal to or higher than the melting point of the low melting point metal component). Another method is to use a press machine capable of heating and pressing at 80° C. to 200° C. and 0.05 MPa to 1 MPa. The preferred pressure range for this method is 0.10 MPa to 1 MPa, and the preferred temperature range is 100°C to 180°C.
• Excellent adhesion tends to be obtained by setting the pressure to 0.10 MPa or higher or the heating temperature to 100° C. or higher. Further, when the pressure is 1 MPa or less or the heating temperature is 180° C. or less, the reliability of adhesion tends to be further improved. This is thought to be because it is possible to prevent the thermally conductive sheet from being excessively compressed and becoming thinner, or from becoming too large in distortion or residual stress in peripheral members.
• the heat conductive sheet disposed between the heating element and the heat radiating element is not particularly limited as long as it is the above-mentioned heat conductive sheet.
• the heat conductive sheet shown in FIGS. 1 to 3 may be placed between a heat generating element and a heat radiating element.
• the thermally conductive sheet 1A shown in FIG. 1 When using the thermally conductive sheet 1A shown in FIG. 1, by heating and pressurizing the thermally conductive sheet 1A with the thermally conductive sheet 1A arranged between the heat generating element and the heat radiating element, the low melting point located on the main surface of the thermally conductive sheet 1A is Metal components 12A and 12C are melted. A gap created when heat-compression bonding the thermally conductive sheet 1A and the heating element and the heat radiating element is filled with a molten low-melting point metal component (corresponding to a metal region). As a result, the gap between the heat conductive sheet and the heat generating element or the heat radiating element is reduced, and the contact thermal resistance is significantly reduced.
• thermally conductive sheet 1B shown in FIG. 2 When using the thermally conductive sheet 1B shown in FIG. 2, heating and pressurizing the thermally conductive sheet 1B with the thermally conductive sheet 1B disposed between the heat generating element and the heat dissipating element allows the low melting point contained inside the thermally conductive sheet 1B to be The metal component 12B melts and easily oozes out onto the surface of the heat conductive sheet 1B. As a result, the gap created when the thermally conductive sheet 1B and the heating element and the heat radiating element are bonded under heat and pressure is melted and filled with the oozing low melting point metal component (corresponding to the metal region). As a result, the gap between the heat conductive sheet and the heat generating element or the heat radiating element is reduced, and the contact thermal resistance is significantly reduced.
• the gap between the heat conductive sheet and the heat generating element or the heat dissipating element is made of particles with a low melting point. Metal components melt. As a result, the gap is filled with a metal region derived from the low melting point metal component, thereby making it possible to significantly reduce the contact thermal resistance.
• the heat conductive sheets included in the heat dissipation device have low It has a metal region derived from a melting point metal component, and the metal regions located on the two main surfaces are in surface contact with the heating element and the heat radiating element, respectively.
• the metal regions 13A and 13C are melted by heating and pressurizing the thermally conductive sheet 1 placed between the heating element and the heat radiating element.
• the gaps created when the heat conductive sheet 1 and the heating element and the heat radiating element are bonded under heat and pressure are filled with the molten metal regions 13A and 13C.
• the gap between the heat conductive sheet and the heat generating element or the heat radiating element is reduced, and the contact thermal resistance is significantly reduced.
• the thermally conductive sheet may have a reduced thickness (compression rate) of 1% to 35% after the heat-conducting sheet is placed between the heat-generating element and the heat-dissipating body relative to its initial thickness before being press-bonded.
• jigs such as screws and springs may be used for fixing, and it is preferable to further fix with commonly used means such as adhesives in order to maintain close contact.
• a modified example of the heat radiating device of the present disclosure includes a heat generating element, a heat radiating element, and a heat conductive sheet according to the above-described modified example disposed between the heating element and the heat radiating element, At least one of the interface with the conductive sheet and the interface between the heat radiator and the heat conductive sheet has a porosity of 0% to 8%, which is calculated as the ratio of the area of the gas region to the area of the measurement region.
• the above-mentioned porosity is 0% to 8%.
• the gaps that occur when heat-compression bonding the thermally conductive sheet and the heat generating element or the heat dissipating element are removed by melting. Since it is filled with a melting point metal component, the contact thermal resistance is significantly reduced.
• the heat conductive layer includes a metal region containing a low melting point metal component on at least a portion of at least one of the main surfaces located on the heat generating body side and the main surface located on the heat dissipation body side. It may be located.
• Example 1 and Example 2 The following materials were put into a kneader kneader (Moriyama Co., Ltd., DS3-SGHM-E model pressurized double-arm kneader) so that the mixing ratio (volume %) was as shown in Table 1, and kneaded at a temperature of 150°C. A composition was obtained.
• the composition obtained by kneading was put into an extrusion molding machine (Parker Co., Ltd., product name: HKS40-15 type extruder) and extruded into a flat plate shape with a width of 20 cm and a thickness of 1.5 mm to 1.6 mm to obtain a primary sheet.
• the obtained primary sheet was press punched using a 40 mm x 150 mm die blade, and 61 of the punched sheets were stacked and heated at 90°C in the stacking direction with a spacer 80 mm in height in between so that the height was 80 mm. Pressure was applied for 30 minutes to obtain a 40 mm x 150 mm x 80 mm laminate.
• the 80 mm x 150 mm side end face of this laminate was sliced with a wood slicer to obtain a thermally conductive layer with a thickness of 0.11 mm.
• thermoly conductive sheet (Preparation of thermally conductive sheet) Solder particles (components Sn-Bi (tin-bismuth alloy), Tin bismuth Alloy Powder (manufactured by 5N Plus Inc.) MCP137 (melting point 137°C) were applied to the two main surfaces of the thermally conductive layer obtained as described above. , average particle diameter: 10 ⁇ m). Thereby, a thermally conductive sheet with solder particles attached to the two main surfaces of the thermally conductive layer was obtained. The maximum thickness of the region of solder particles attached to the heat conductive sheet is as shown in Table 1.
• Example 3 and Example 4 instead of sprinkling solder particles on the two main surfaces of the thermally conductive layer in Examples 1 and 2, solder particles (component Sn-Bi (tin-bismuth) were added to the composition in the kneading process for preparing the thermally conductive layer The mixture was kneaded, laminated, pressed, and sliced in the same steps as in Examples 1 and 2, except that the composition was prepared to have the mixing ratio (volume %) shown in Table 1. , a thermally conductive layer was prepared. In Examples 3 and 4, a thermally conductive layer containing solder particles was used as a thermally conductive sheet.
• solder particles component Sn-Bi (tin-bismuth
• Thermal resistance was measured using a tabletop xenon flash analyzer (LFA 467 Hyper Flash).
• the thermally conductive sheets of Examples 1 to 4 or Comparative Example 1 punched to a diameter of 14 mm were sandwiched between 1 mm copper plates to produce samples with a three-layer structure.
• the sample preparation conditions were as follows: The sample was pressurized at a temperature of 150° C. and a pressure of 120 psi for 3 minutes, and then sufficiently cooled to room temperature. In addition, as a pretreatment for measurement, the copper surface was blackened using carbon spray, and then measured.
• Thickness evaluation Using a micrometer, measure the maximum thickness of the thermally conductive sheet before compression ("Thickness before compression” in Table 2) and the maximum thickness of the metal region before compression ("Thickness of metal region before compression” in Table 2). And the maximum thickness of the thermally conductive sheet after compression (“thickness after compression” in Table 2) was measured. Regarding the maximum thickness of the metal region before compression, calculate the maximum thickness of the thermal conductive layer before compression and the maximum thickness of the thermal conductive sheet before compression, and calculate the maximum thickness of the thermal conductive layer before compression from the maximum thickness of the thermal conductive sheet before compression. The maximum thickness of the metal region was determined by subtracting the maximum thickness of .

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