Solid heat conduction material

Abstract

According to the present invention, it is possible to provide a TIM which can eliminate the disadvantages in conventional TIMs, has improved adaptability to both existing production lines and design, and is not susceptible to performance degradation due to long-term use or repeated use. The invention provides a solid heat conduction material. The solid heat conduction material comprises amorphous thermoplastic resin and heat dissipation filler.

Description

Technical Field

[0001] The present invention relates to solid heat-conducting materials. Background Art

[0002] A thermal interface material (hereinafter referred to as "TIM") is a heat-conducting material inserted between components to effectively release unnecessary heat generated inside an electronic device. TIM is generally used in a form inserted between a heat-generating body such as an IC (integrated circuit) and a heat-dissipating component such as a heat sink or a heat-dissipating plate, or in a form inserted between heat-dissipating components.

[0003] Conventionally, various shaped materials such as thermal grease (for example, Patent Document 1), thermal gap filler, phase change material (hereinafter referred to as "PCM") (for example, Patent Document 2), heat sink (for example, Patent Document 3), etc. are known as TIM, and corresponding materials are used according to each application.

[0004] Thermal grease is a viscous liquid material obtained by adding heat-conductive particles such as metal powder to a resin such as polysiloxane. Since it does not require curing (heat treatment), it is widely used for heat dissipation of ICs such as CPUs (central processing units). Since thermal grease is liquid, it has the advantages of being able to follow and conform to even complex-shaped unevenness, thereby improving the heat conduction efficiency, and having high flexibility, so it can also cope with thickness adjustment during construction. On the other hand, regarding the storage and coating of thermal grease, various products have their own know-how, resulting in poor operability and low adaptability to existing production lines. In addition, when thermal grease is used in a manner of filling between components with different thermal expansion characteristics, during the repeated operation / stop process of the device, it is easy to cause a phenomenon called "pump out" where the liquid grease located between the components is slowly extruded to the outside and gradually decreases, or a phenomenon where the volatile components of the resin are separated, the resin is cured and deteriorated into a powder with long-term use, and there are still problems with reliability in long-term use.

[0005] Thermal gap filler is a liquid heat-conductive gap filling material used for coating electronic components to fill air accumulation or gaps. Since thermal gap filler is also liquid, it has the advantage of being able to follow and conform to even complex-shaped unevenness, thereby providing a high-efficiency thermal interface without air gaps after curing. On the other hand, thermal gap filler also has the same disadvantages as the above-mentioned thermal grease, namely poor operability and low adaptability to existing production lines.

[0006] PCM has a thermoplastic resin as its main component and is a heat-conducting material designed to be solid at normal temperature and become liquid at 60 to 80°C during IC operation. According to this design, since it softens during IC operation and has good adhesion to the heat sink, it can follow and adhere to complex-shaped unevenness, thus improving the heat-conducting efficiency. However, since PCM repeatedly changes its shape between solid and liquid as the device operates / halts, volume change or shape change is likely to occur during solidification, and there is a high probability of generating voids, which reduces the heat dissipation efficiency. In addition, it must be stored refrigerated before use, which has the drawback of low adaptability to existing production lines. Moreover, since it solidifies at normal temperature and adheres to ICs etc., there is also the drawback that it is difficult to rework the components.

[0007] The heat sink is a sheet-shaped resin material filled with fillers, which is easy to control the thickness important for TIM, and because of its excellent shape control and stable performance, it is suitable for applications where it is difficult to use liquid materials, such as filling relatively large unevenness. And since it is in sheet form, it is easy to handle and easy to rework (replace), so it is widely used as a heat-conducting material. However, the heat sink is not as soft as liquid materials, it is difficult to follow and adhere to complex-shaped unevenness, and it cannot handle thickness adjustment during construction etc., which has the drawback of low adaptability to design.

[0008] Prior art documents

[0009] Patent documents

[0010] Patent document 1: Japanese Patent Application Laid-Open No. 2006-188638

[0011] Patent document 2: Japanese Patent Application Laid-Open No. 2010-21165

[0012] Patent document 3: Japanese Patent Application Laid-Open No. 2020-13872 Summary of the invention

[0013] Problems to be solved by the invention

[0014] The present invention has been completed in view of such a technical background, and its object is to provide a TIM that can eliminate the drawbacks of conventional TIMs, has high adaptability to existing production lines and to design, and is not likely to experience performance degradation due to long-term or repeated use.

[0015] In this specification, "high adaptability to existing production lines" means that there are no special restrictions on storage, coating, etc., and the operability is excellent. "High adaptability to design" means that it can follow and adhere to complex-shaped unevenness, has high flexibility, and can also handle thickness adjustment during construction etc.

[0016] Means for solving the problems

[0017] To achieve the foregoing object, the present invention provides the following solutions.

[0018] <Solid thermal conductive material>

[0019] [1]. A solid thermal conductive material comprising an amorphous thermoplastic resin and a heat dissipation filler.

[0020] [2]. The solid thermal conductive material according to [1], wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less.

[0021] [3]. The solid thermal conductive material according to [2], wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin.

[0022] [4]. The solid thermal conductive material according to [3], wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having an epoxy equivalent of 1600 or more, or an amorphous thermoplastic resin containing no epoxy group.

[0023] [5]. The solid thermal conductive material according to any one of [1] to [4], wherein the content of the heat dissipation filler is 30 to 95% by volume.

[0024] [6]. The solid thermal conductive material according to any one of [1] to [5], wherein the heat dissipation filler is at least one selected from silver, alumina, magnesia, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, silicon dioxide, carbon black, carbon nanofibers, carbon nanotubes, silicon carbide, and silicon nitride.

[0025] <Electronic device>

[0026] [7]. An electronic device comprising a thermal conductive layer formed of a solid thermal conductive material, the solid thermal conductive material comprising an amorphous thermoplastic resin and a heat dissipation filler.

[0027] [8]. The electronic device according to [7], wherein the thermal conductive layer present between the heat generating body and the heat dissipating member, or the thermal conductive layer present between the heat dissipating members, is formed by melting and solidifying the solid thermal conductive material between the heat generating body and the heat dissipating member, or between the heat dissipating members.

[0028] [9]. The electronic device according to [7] or [8], wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less.

[0029]

[10] . The electronic device according to [9], wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin.

[0030]

[11] . The electronic device as described in

[10] , wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin with an epoxy equivalent of 1600 or more, or an amorphous thermoplastic resin without an epoxy group.

[0031]

[12] . The electronic device as described in any one of [7] to

[11] , wherein the content of the heat dissipation filler is 30 to 95% by volume.

[0032]

[13] . The electronic device as described in any one of [7] to

[12] , wherein the heat dissipation filler is at least one selected from silver, alumina, magnesia, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, silicon dioxide, carbon black, carbon nanofibers, carbon nanotubes, silicon carbide, and silicon nitride.

[0033]

[14] . The electronic device as described in [8], wherein the melting is performed by heating and pressing the solid heat conductive material.

[0034]

[15] . The electronic device as described in

[14] , wherein the heating and pressing are performed under the conditions of 100 to 400 °C and 0.01 to 20 MPa.

[0035] Advantages of the Invention

[0036] Through the present invention, it is possible to provide a TIM that can eliminate the disadvantages of conventional TIMs, has improved adaptability to existing production lines and to designs, and is less likely to experience performance degradation during long-term or repeated use. Description of the Drawings

[0037] Figure 1 It is an explanatory diagram of the heat conductive layer of the electronic device according to an embodiment of the present invention. Detailed Description of the Embodiment

[0038] The following provides a detailed description of the embodiments of the present invention.

[0039] In this specification, "connection" means connecting things into one body, and "joining" is a subordinate concept thereof. In this specification, "joining" means connecting things in contact with each other, and "adhesion" and "welding" are subordinate concepts thereof. "Adhesion" means forming a joined state between two adherends (things to be adhered) by means of an organic material (such as a thermosetting resin or a thermoplastic resin) like a tape or an adhesive. "Welding" means melting the surface of a thermoplastic resin or the like by heat, cooling, and solidifying it, thereby forming a joined state through molecular diffusion and entanglement.

[0040] [Solid Heat Conductive Material]

[0041] The solid heat conductive material contains an amorphous thermoplastic resin and a heat dissipation filler.

[0042] From the aspect of fully endowing the solid heat-conducting material with the properties of an amorphous thermoplastic resin, the content of the amorphous thermoplastic resin is preferably 51% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more in the resin component of the solid heat-conducting material.

[0043] The so-called amorphous thermoplastic resin in the present invention refers to a resin that has a melting point (Tm), but in the measurement using a differential scanning calorimeter (DSC), no endothermic peak associated with melting is confirmed as a distinct endothermic peak, or the endothermic peak is very small.

[0044] The amorphous thermoplastic resin is preferably an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less.

[0045] The heat of fusion is calculated based on the endothermic peak area of the DSC (differential scanning calorimeter) and the mass of the thermoplastic resin component. When an inorganic filler or the like is contained in the solid heat-conducting material, it is calculated based on the mass of the thermoplastic resin component other than the inorganic filler. Specifically, 2 to 10 mg of the sample can be weighed and placed in an aluminum pan, and using a DSC (DSC8231 manufactured by Rigaku Corporation), it is heated from 23°C to 200°C or more at 10°C / min to obtain a DSC curve, and then calculated based on the endothermic peak area at the time of melting obtained from the DSC curve and the weighed value.

[0046] The heat of fusion of the amorphous thermoplastic resin is more preferably 11 J / g or less, still more preferably 7 J / g or less, still more preferably 4 J / g or less, and most preferably the melting peak is below the detection limit.

[0047] The solid heat-conducting material containing an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less does not exhibit a sharp decrease in viscosity during heating and does not become a low-viscosity (0.001 to 100 Pa·s) state even in a high-temperature region exceeding 200°C. Therefore, this solid heat-conducting material does not melt and flow out, and the thickness after curing can also be maintained within a specific range, enabling a high bonding strength to be stably obtained and pump-out to be avoided.

[0048] When the amorphous thermoplastic resin contained in the solid heat-conducting material has a melting point, the melting point is preferably 50 to 400°C, more preferably 60°C to 350°C, still more preferably 70°C to 300°C. By having a melting point within the range of 50 to 400°C, the solid heat-conducting material is effectively deformed and melted by heating and effectively wets and spreads between the heating element and the heat-dissipating component and / or between the heat-dissipating components, so a high bonding strength can be obtained.

[0049] The melting point of the so-called amorphous thermoplastic resin in this specification refers to the temperature range in which it substantially starts to soften from a solid, has thermoplasticity, and can be melted and joined, and refers to the melting peak temperature measured by DSC. In addition, when the melting peak cannot be obtained, the temperature obtained by adding 70°C to the glass transition temperature is used as the melting point. The glass transition temperature refers to the temperature at which the DSC curve starts to decline during the second cycle of heating to 200°C after heating to 200°C by DSC, cooling to below 40°C, and then heating to 200°C.

[0050] The amorphous thermoplastic resin is preferably at least one of a thermoplastic epoxy resin and a phenoxy resin. Since the thermoplastic epoxy resin and the phenoxy resin have low cohesive force in the resin and have hydroxyl groups, the interaction with the heating element and the heat dissipation component is strong, and they can be joined with high bonding force. In addition, since the thermoplastic epoxy resin and the phenoxy resin have excellent flexibility and toughness, a high-strength bond can be obtained.

[0051] The amorphous thermoplastic resin is preferably an amorphous thermoplastic resin with an epoxy equivalent of 1600 or more, or an amorphous thermoplastic resin without an epoxy group.

[0052] The epoxy equivalent (the mass of the thermoplastic resin contained in 1 mole of epoxy groups) is the value of the epoxy equivalent of the thermoplastic resin contained in the solid thermal conductive material before being assembled into the electronic device, and is the value measured by the method specified in JIS-K7236:2001 (unit "g / eq"). Specifically, using a potentiometric titration device, adding a tetraethylammonium bromide acetic acid solution, using a 0.1 mol / L perchloric acid - acetic acid solution, for the solvent-diluted product (resin varnish), calculate the value in terms of the solid content based on the non-volatile components, and use the obtained value as the epoxy equivalent. In addition, in the case of a mixture of two or more resins, it can also be calculated based on the respective contents and epoxy equivalents.

[0053] The epoxy equivalent of the amorphous thermoplastic resin is more preferably 2,000 or more, further preferably 5,000 or more, still further preferably 9,000 or more, and most preferably above the detection limit and substantially no epoxy groups are detected. In addition, the epoxy equivalent being above the detection limit means that no epoxy groups are detected when measuring the epoxy equivalent based on JIS K 7236:2001 described later.

[0054] By containing an amorphous thermoplastic resin with an epoxy equivalent of 1600 or more and a heat of fusion of 15 J / g or less in the solid thermal conductive material, the sharp decrease in viscosity can be more effectively suppressed, and a higher bonding force can be stably obtained.

[0055] Since the solid heat-conductive material of the present invention is thermoplastic and can be reversibly softened / melted and solidified repeatedly, it can be stored in solid form before being assembled into an electronic device. After becoming liquid at the assembly site, it is assembled as a solid. Since it can be stored in solid form before being assembled into an electronic device, special technologies related to storage and assembly operations are not required, and the adaptability to existing production lines is excellent. Since it melts at the assembly site, it can follow and conform to even complex-shaped unevenness and then solidify, so the adaptability to various designs is high. Moreover, since it can be reversibly softened / melted and solidified repeatedly, pumping out does not occur and pores are not easily formed, and performance degradation associated with long-term use and repeated use can be avoided.

[0056] "Thermoplastic Epoxy Resin"

[0057] The thermoplastic epoxy resin is preferably a polymer formed from (a) a bifunctional epoxy resin monomer or oligomer and (b) a bifunctional compound having two identical or different functional groups selected from phenolic hydroxyl groups, carboxyl groups, mercapto groups, isocyanate groups, and cyanate groups.

[0058] By using this compound, the polymerization reaction to form a linear polymer can proceed preferentially, and a thermoplastic epoxy resin with the required properties can be obtained.

[0059] The (a) bifunctional epoxy resin monomer or oligomer refers to an epoxy resin monomer or oligomer having two epoxy groups in the molecule.

[0060] Specific examples of the above (a) include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, 2-functional phenol novolak type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, 2-functional naphthalene type epoxy resin, 2-functional alicyclic epoxy resin, 2-functional glycidyl ester type epoxy resin (such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl dimer acid, etc.), 2-functional glycidylamine type epoxy resin (such as diglycidyl aniline, diglycidyl toluidine, etc.), 2-functional heterocyclic epoxy resin, 2-functional diaryl sulfone type epoxy resin, hydroquinone type epoxy resin (such as hydroquinone diglycidyl ether, 2,5-di-tert-butyl hydroquinone diglycidyl ether, resorcinol diglycidyl ether, etc.), 2-functional alkylene glycidyl ether compounds (such as butanediol diglycidyl ether, butenediol diglycidyl ether, butynediol diglycidyl ether, etc.), 2-functional glycidyl group-containing hydantoin compounds (such as 1,3-diglycidyl-5,5-dialkyl hydantoin, 1-glycidyl-3-(glycidyloxyalkyl)-5,5-dialkyl hydantoin, etc.), 2-functional glycidyl group-containing siloxanes (such as 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane, α,β-bis(3-glycidyloxypropyl)polydimethylsiloxane, etc.) and their modified products. Among these, from the viewpoints of reactivity and workability, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl type epoxy resin are preferred.

[0061] Specific examples of the 2-functional compound having a phenolic hydroxyl group of the above (b) include mononuclear aromatic dihydroxy compound classes having 1 benzene ring such as catechol, resorcinol, hydroquinone, etc., bisphenols such as bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)methane (bisphenol F), bis(4-hydroxyphenyl)ethane (bisphenol AD), etc., compounds having a condensed ring such as dihydroxynaphthalene, 2-functional phenolic compounds having an allyl group introduced such as diallyl resorcinol, diallyl bisphenol A, triallyl dihydroxybiphenyl, etc., and dibutyl bisphenol A.

[0062] Specific examples of the carboxyl group-containing compound of the above (b) include adipic acid, succinic acid, malonic acid, cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, etc.

[0063] Specific examples of the 2-functional compound having a mercapto group of the above (b) include ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, etc.

[0064] Specific examples of the bifunctional compound having an isocyanate group as described in (b) include diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI), toluene diisocyanate (TDI), and the like.

[0065] Specific examples of the bifunctional compound having a cyanate group as described in (b) include 2,2-bis(4-cyanatophenyl)propane, 1,1-bis(4-cyanatophenyl)ethane, bis(4-cyanatophenyl)methane, and the like.

[0066] In (b), from the viewpoint of obtaining a thermoplastic polymer, a bifunctional compound having a phenolic hydroxyl group is preferred. From the viewpoints of heat resistance and bonding property, a bifunctional compound having two phenolic hydroxyl groups and having a bisphenol structure or a biphenyl structure is preferred. From the viewpoints of heat resistance and cost, bisphenol A, bisphenol F, or bisphenol S is preferred.

[0067] When (a) is bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, or biphenyl type epoxy resin, and (b) is bisphenol A, bisphenol F, or bisphenol S, the polymer obtained by polymerizing (a) and (b) has a main chain with a p-phenylene structure and an ether bond as the main skeleton and connected by an alkylene group, and has a structure in which hydroxyl groups generated by polymerization addition are arranged in the side chain.

[0068] Through the linear structure formed by the p-phenylene skeleton, the mechanical strength of the polymer after polymerization can be improved, and through the hydroxyl groups arranged in the side chain, the adhesion can be improved. As a result, high bonding strength can be achieved while maintaining the workability of the thermosetting resin.

[0069] "Phenoxy Resin"

[0070] Phenoxy resin is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin and has thermoplasticity. Regarding the manufacture of phenoxy resin, a method of directly reacting a dihydric phenol with epichlorohydrin and a method of addition polymerization reaction of a diglycidyl ether of a dihydric phenol with a dihydric phenol are known. The phenoxy resin used in the present invention can be obtained by any method. In the case of directly reacting a dihydric phenol with epichlorohydrin, examples of the dihydric phenol include phenols such as bisphenol A, bisphenol F, bisphenol S, biphenol, biphenyl diol, and fluorene diphenyl; aliphatic diols such as ethylene glycol, propylene glycol, and diethylene glycol. Among them, from the viewpoints of cost, bonding property, viscosity, and heat resistance, bisphenol A, bisphenol F, and bisphenol S are preferred. They can be used alone or in combination of two or more.

[0071] The phenoxy resin has a chemical structure similar to that of an epoxy resin, having a main chain in which a p-phenylene structure and an ether bond are used as a main skeleton and are connected to each other, and having a structure in which hydroxyl groups are arranged on the side chains.

[0072] "Weight-average Molecular Weight of Thermoplastic Epoxy Resin and Phenoxy Resin"

[0073] The weight-average molecular weight of the thermoplastic epoxy resin and the phenoxy resin, which is a value in terms of polystyrene conversion measured by GPC (gel permeation chromatography), is preferably 10,000 to 500,000, more preferably 18,000 to 300,000, and still more preferably 20,000 to 200,000. The weight-average molecular weight is calculated based on the elution peak position detected by GPC and is a value of the molecular weight obtained by conversion with standard polystyrene. When the weight-average molecular weight is within this value range, the balance between thermoplasticity and heat resistance is good and the heat resistance is also high. When the weight-average molecular weight is 10,000 or more, the heat resistance is excellent, and when it is 500,000 or less, the viscosity during melting is low and the bonding property becomes high.

[0074] "Amorphous Thermoplastic Resins Other than Thermoplastic Epoxy Resin and Phenoxy Resin"

[0075] Examples of amorphous thermoplastic resins other than thermoplastic epoxy resin and phenoxy resin include polystyrene, polymethyl methacrylate, AS resin, ABS resin, polycarbonate, polyimide, polyamideimide, polyetherimide, polyethersulfone, polyphenylene ether and its modified products, polyarylate, and the like.

[0076] "Resin Components Other than Amorphous Thermoplastic Resins"

[0077] The solid heat-conductive material may contain resin components other than amorphous thermoplastic resins. Examples of resin components other than amorphous thermoplastic resins include crystalline thermoplastic resins. The content of resin components other than amorphous thermoplastic resins is preferably 20% by mass or less, more preferably 10% by mass or less, of all the resin components contained in the solid heat-conductive material.

[0078] "Manufacturing Method of Solid Heat-Conductive Material"

[0079] There is no particular limitation on the manufacturing method of the solid heat-conductive material. For example, it can be obtained by heating and polymerizing a composition obtained by adding a heat-dissipating filler to a monomer or oligomer of a bifunctional epoxy compound. When polymerizing, a solvent may also be added in order to reduce the viscosity and facilitate stirring. When a solvent is added, it must be removed, and the solid heat-conductive material can also be obtained by drying, polymerizing, or both on a release film or the like.

[0080] "Heat-Dissipating Filler"

[0081] There is no particular limitation on the type of heat dissipation filler, and examples thereof include metal particles, non-metal particles, etc. with excellent thermal conductivity. Examples include metal particles, particles obtained by plating resin particles with gold, particles obtained by applying an insulating coating to the outermost layer of the particles after plating the resin particles with gold, etc.

[0082] The heat dissipation filler can be, for example, a filler with a thermal conductivity of 10 W / (m·K) or more. The heat dissipation filler can be insulating or conductive.

[0083] Examples of the heat dissipation filler include metals, metal oxides, metal nitrides, metal hydroxides, metal carbides, metal fluorides, carbon, etc., and one of them can be used, or two or more of them can be used in combination. Specifically, examples include aluminum, copper, silver, magnesium oxide, aluminum oxide, zinc oxide, iron oxide, silicon dioxide, beryllium oxide, tin oxide, boron nitride, aluminum nitride, silicon nitride, magnesium hydroxide, aluminum hydroxide, boron carbide, silicon carbide, aluminum fluoride, calcium fluoride, carbon black, carbon nanofibers, carbon nanotubes, diamond, fullerene, graphite.

[0084] Among these, particularly from the viewpoints of thermal conductivity, chemical stability, ease of acquisition, etc., it is preferable to use one or two or more selected from silver, aluminum oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, silicon dioxide, carbon black, carbon nanofibers, carbon nanotubes, silicon carbide, and silicon nitride.

[0085] There is no particular limitation on the average particle size of the heat dissipation filler, but it can be 0.1 μm to 50 μm, or 0.2 μm to 20 μm, or 0.5 μm to 10 μm. If the average particle size is within the above range, the filling density of the heat dissipation filler can be increased. The higher the filling density, the more contact points of the heat dissipation filler, and the higher the thermal conductivity.

[0086] In order to increase the filling rate, two or more heat dissipation fillers with different average particle sizes may also be contained.

[0087] The average particle size can be represented by D50 based on volume. D50 based on volume corresponds to the particle size when the mass cumulative is 50% when drawing a mass cumulative particle size distribution curve from the small particle size side. D50 can be measured by the Coulter counting method or the laser diffraction scattering method (such as "Microtrac series MT3300" manufactured by Nikkiso Co., Ltd.). For example, in the case of spherical alumina particles, it is preferably measured by the Coulter counting method, and in the case of flaky hexagonal boron nitride particles, it is preferably measured by the laser diffraction scattering method.

[0088] The shape of the heat dissipation filler can be various shapes such as spherical, plate-like, polygonal, granular, fibrous, etc.

[0089] When using an anisotropic heat dissipation filler, by appropriately controlling the orientation in the composition, it is possible to improve the strength, thermal conductivity, etc. of the resin composition in a specific direction.

[0090] The content of the heat dissipation filler may be 30 to 95% by volume, preferably 40 to 95% by volume, more preferably 50 to 90% by volume, and particularly preferably 60 to 80% by volume.

[0091] The content (% by volume) of the heat dissipation filler is determined based on the addition amount at 25°C, and is calculated by the following formula (1) with respect to the mass% of the filler, based on the specific gravity of the components other than the filler and the true specific gravity of the filler.

[0092] (Formula 1)

[0093] X = (MF / DF) ÷ (MF / DF + (100 - MF) / DR) × 100%

[0094] In formula (1),

[0095] X: Content (% by volume) of the heat dissipation filler

[0096] MF: Addition amount (mass%) of the heat dissipation filler

[0097] DR: Specific gravity after curing of the resin component

[0098] DF: True specific gravity of the heat dissipation filler.

[0099] Specifically, for example, the content (% by volume) of the heat dissipation filler is calculated by the following steps.

[0100] (Step 1) Measure the specific gravity (DR) of the entire solid heat-conducting material with a hydrometer.

[0101] (Step 2) Measure the mass of the solid heat-conducting material, dissolve the resin component of the solid heat-conducting material with an appropriate organic solvent, and separate the heat dissipation filler by filtration or centrifugation.

[0102] (Step 3) After drying the heat dissipation filler separated in Step 2, measure the mass.

[0103] (Step 4) Identify the composition and crystal structure of the heat dissipation filler based on the XRD pattern, and obtain the pure crystal specific gravity (true specific gravity: DF) of the heat dissipation filler. The analysis of the crystal structure can use known methods such as Rietveld analysis.

[0104] (Step 5) Calculate the content (mass%: MF) of the heat dissipation filler based on the mass of the solid heat-conducting material measured in Step 2 and the mass of the heat dissipation filler measured in Step 3.

[0105] (Step 6) Calculate the volume percentage "X" based on the above (Equation 1), "DR" in Step 1, "DF" in Step 4, and "MF" in Step 5 above.

[0106] By setting the content of the heat dissipation filler to 30% by volume or more, the packing density of the heat dissipation filler can be increased. The higher the packing density, the more contact points of the heat dissipation filler, and the higher the thermal conductivity.

[0107] The solid thermal conductive material with the content of the heat dissipation filler being 95% by volume or less has good moldability and can be easily molded into a thin sheet shape. In addition, by setting the content of the heat dissipation filler to 95% by volume or less, a high bonding strength can be obtained.

[0108] As needed, other additives may be contained in addition to the heat dissipation filler within the scope not detrimental to the object of the present invention.

[0109] Examples of the above other additives include, for example, viscosity modifiers, inorganic fillers, organic fillers (resin powders), defoamers, coupling agents such as silane coupling agents, pigments, etc., and one of them or a combination of two or more thereof can be used.

[0110] As the viscosity modifier, for example, a reactive diluent can be used.

[0111] The inorganic filler herein refers to an inorganic filler not included in the heat dissipation filler with excellent thermal conductivity, and can be used for the purpose of improving strength, etc. Examples include spherical fused silica, silica sand, talc, calcium carbonate, mica, acid clay, diatomaceous earth, kaolin, quartz, titanium oxide, silicon oxide, hollow glass spheres, etc.

[0112] The solid thermal conductive material thus obtained has excellent storage stability because the content of unreacted monomers or terminal epoxy groups is small or substantially absent, can be stored at room temperature for a long time, and has high adaptability to existing production lines.

[0113] There is no particular limitation on the form of the solid thermal conductive material, but it is preferably in any shape selected from a film, rod, particle, and powder. Particularly preferably, at least one side of the outer shape is 5 mm or less, more preferably 3 mm or less, further preferably 1 mm or less, still further preferably 0.5 mm or less, and most preferably 0.3 mm or less. If the size is within this range, it can spread efficiently on the bonding surface by heating and pressing, and a high bonding strength can be obtained.

[0114] The solid thermal conductive material may have tackiness within the range not hindering the bonding strength or its heat resistance.

[0115] [Electronic device]

[0116] The electronic device of the present invention includes a heat-conducting layer formed of a solid heat-conducting material, and the solid heat-conducting material includes an amorphous thermoplastic resin and a heat-dissipating filler.

[0117] The heat-conducting layer present between the heat-generating body A and the heat-dissipating member B, and / or between the heat-dissipating member A' and the heat-dissipating member B' is preferably formed by melting and solidifying the solid heat-conducting material C between the heat-generating body A and the heat-dissipating member B, and / or between the heat-dissipating member A' and the heat-dissipating member B'.

[0118] The heat-generating body A and the heat-dissipating member B, and / or the heat-dissipating member A' and the heat-dissipating member B' are each preferably at least one of ceramics, carbon materials, or metals.

[0119] The metal is preferably at least one selected from aluminum, iron, copper, magnesium, and their alloys. From the viewpoints of bonding force and strength, and from the viewpoint of the strength of the interfacial bonding force with the solid heat-conducting material, if at least one of aluminum alloy and iron alloy is used, a strong bonded body can be obtained, so it is particularly preferred.

[0120] The ceramic is preferably one selected from silicon carbide, aluminum nitride, alumina, silicon nitride, cermet, yttrium oxide, forsterite, cordierite, zirconia, and steatite. From the viewpoints of heat conductivity, cost, and ease of molding, alumina is more preferred.

[0121] Pretreatments suitable for each component can also be performed on the heat-generating body A and the heat-dissipating member B, and / or the heat-dissipating member A' and the heat-dissipating member B'. As the pretreatment, a pretreatment for cleaning the surface or a pretreatment for imparting irregularities to the surface is preferred. Specifically, when the heat-generating body A and the heat-dissipating member B, and / or the heat-dissipating member A' and the heat-dissipating member B' are made of aluminum, ceramics, or iron, at least one selected from degreasing treatment, UV ozone treatment, sandblasting treatment, polishing treatment, plasma treatment, and etching treatment is preferred.

[0122] The pretreatment can be only one type, or two or more types can be performed. As specific methods of these pretreatments, known methods can be used.

[0123] [Method for forming a heat-conducting layer in an electronic device]

[0124] As Figure 1 shown, the heat-conducting layer can be formed by joining the heat-generating body A and the heat-dissipating member B, and / or the heat-dissipating member A' and the heat-dissipating member B' with the solid heat-conducting material C interposed therebetween.

[0125] The following method a, method b, and method c can be cited as examples.

[0126] [Method a]

[0127] Method a is a method of joining the heat generating body A to the heat dissipating member B and / or the heat dissipating member A' to the heat dissipating member B' with the solid heat conducting material C interposed therebetween, by joining the solid heat conducting material C to the heat dissipating member B or the heat dissipating member B', bringing the solid heat conducting material C in the state of being joined to the heat dissipating member B or the heat dissipating member B' into surface contact with the heat generating body A or the heat dissipating member A', and then melting and solidifying the solid heat conducting material C.

[0128] In method a, first, as step a1, the solid heat conducting material C is pre-joined to the heat dissipating member B or the heat dissipating member B'.

[0129] By pre-joining the solid heat conducting material C to the heat dissipating member B and / or the heat dissipating member B', the heat generating body can be joined to the heat dissipating member with good accuracy. At this time, the solid heat conducting material may also have tackiness.

[0130] Next, as step a2, the solid heat conducting material C in the state of being joined to the heat dissipating member B and / or the heat dissipating member B' is brought into surface contact with the heat generating body A or the heat dissipating member A', and the solid heat conducting material C is melted and then solidified.

[0131] When the surface of the heat generating body A and / or the heat dissipating member A' has irregularities, by pressing the melted solid heat conducting material C against the irregularities, the solid heat conducting material C can follow the irregularities. The irregularities may also be pressed against the melted solid heat conducting material C to make the solid heat conducting material C follow the irregularities.

[0132] The solid heat conducting material C solidifies in a state following the irregularities, and the heat generating body A can be joined to the heat dissipating member B, and / or the heat dissipating member A' can be joined to the heat dissipating member B'.

[0133] From the viewpoint of obtaining a high joining force, it is preferable to heat the solid heat conducting material to a temperature above its melting point to melt the solid heat conducting material.

[0134] In method a, the method of melting and solidifying the solid heat conducting material is as described in the following "Melting and Solidifying".

[0135] [Method b]

[0136] Method b is a method of joining the heat generating body A to the heat dissipating member B and / or the heat dissipating member A' to the heat dissipating member B' with the solid heat conducting material C interposed therebetween, by joining the solid heat conducting material C to the heat generating body A and / or the heat dissipating member A', bringing the solid heat conducting material C in the state of being joined to the heat generating body A and / or the heat dissipating member A' into surface contact with the heat dissipating member B or the heat dissipating member B', and then melting and solidifying the solid heat conducting material C.

[0137] In method b, first, as step b1, the solid heat conducting material C is pre-joined to the heat generating body A and / or the heat dissipating member A'.

[0138] By pre-bonding the solid heat-conducting material C with the heating element A and / or the heat-dissipating component A', the heating element A can be bonded to the heat-dissipating component B and / or the heat-dissipating component A' can be bonded to the heat-dissipating component B' with good precision. At this time, the solid heat-conducting material may also have contact adhesiveness.

[0139] Next, as step b2, the solid heat-conducting material C in a state of being bonded to the heating element A and / or the heat-dissipating component A' is brought into surface contact with the heat-dissipating component B or the heat-dissipating component B', and the solid heat-conducting material C is melted and then solidified.

[0140] When the surface of the heat-dissipating component B and / or the heat-dissipating component B' has irregularities, by pressing the molten solid heat-conducting material against the heat-dissipating component, the solid heat-conducting material can follow the irregularities. The irregularities can also be pressed against the molten solid heat-conducting material to make the solid heat-conducting material follow the irregularities.

[0141] The solid heat-conducting material is solidified in a state of following the irregularities, and the heating element A can be bonded to the heat-dissipating component B, and / or the heat-dissipating component A' can be bonded to the heat-dissipating component B'.

[0142] From the viewpoint of obtaining a high bonding force, it is preferable to heat the solid heat-conducting material to melt it at a temperature above the melting point of the solid heat-conducting material.

[0143] In method b, the method of melting and then solidifying the solid heat-conducting material is as described in "Melting and Solidifying" described later.

[0144] [Method c]

[0145] Method c is a method of bonding the heating element to the heat-dissipating component with the solid heat-conducting material interposed therebetween by melting and then solidifying the solid heat-conducting material C in a state where the heating element A, the solid heat-conducting material C, and the heat-dissipating component B are arranged in this order, and / or in a state where the heat-dissipating component A', the solid heat-conducting material C, and the heat-dissipating component B' are arranged in this order.

[0146] In method c, first, as step c1, the heating element A, the solid heat-conducting material C, and the heat-dissipating component B are arranged and laminated in this order, and / or the heat-dissipating component A', the solid heat-conducting material C, and the heat-dissipating component B' are arranged in this order to form a laminate. The laminate is formed by overlapping the respective independent components in a state where the heating element A and the solid heat-conducting material C, the solid heat-conducting material C and the heat-dissipating component B, the heat-dissipating component A' and the solid heat-conducting material C, and the solid heat-conducting material C and the heat-dissipating component B' are not previously bonded. At this time, the solid heat-conducting material may also have contact adhesiveness.

[0147] Next, as step c2, the solid heat-conducting material C in the above laminate is melted and then solidified.

[0148] When the surface of the heating element A and / or the heat dissipation member A' has irregularities and / or when the surface of the heat dissipation member B or the heat dissipation member B' has irregularities, in a state where the solid heat conductive material C is melted, a force is applied and pressed from the side of the heating element A and / or the heat dissipation member A', or from the side of the heat dissipation member B or the heat dissipation member B', or from both the side of the heating element A and / or the heat dissipation member A' and the side of the heat dissipation member B or the heat dissipation member B' toward the solid heat conductive material C, and the solid heat conductive material C can follow the irregularities.

[0149] The solid heat conductive material C is cured in a state of following the irregularities, and the heating element A and the heat dissipation member B, and / or the heat dissipation member A' and the heat dissipation member B' can be joined.

[0150] When melting the solid heat conductive material in the laminate, from the viewpoint of obtaining a high joining force, it is preferable to heat and melt the solid heat conductive material at a temperature above the melting point of the solid heat conductive material.

[0151] In the c method, the method of melting and then curing the solid heat conductive material is as described in the following "Melting and Curing".

[0152] [Combination]

[0153] The assembling method of the solid heat conductive material may have a combination of at least two steps selected from the a1 step in the above a method, the b1 step in the b method, and the c1 step in the c method.

[0154] As an example, a combination of the a1 step and the b1 step can be cited.

[0155] For example, the joined body a obtained by joining the solid heat conductive material C and the heat dissipation member B through the a1 step and the joined body b obtained by joining the solid heat conductive material C and the heating element A through the b1 step are in surface contact with the solid heat conductive materials C of the joined body a and the joined body b facing each other, and the solid heat conductive materials C of both are melted and then cured. At this time, in a state where the solid heat conductive material C is melted, a force can be applied and pressed from the side of the joined body a, or from the side of the joined body b, or from both the side of the joined body a and the side of the joined body b toward the solid heat conductive material C to form a joined body. That is, the manufacturing method of the joined body having a combination of the a1 step and the b1 step can join the heating element and the heat dissipation member using two solid heat conductive materials.

[0156] In addition, as another example, a combination of the a1 step and the c1 step can be cited.

[0157] For example, in step c1, instead of the heat dissipation component B, an assembly a obtained by joining the solid heat conductive material C to the heat dissipation component B in step a1 is arranged. At this time, the solid heat conductive material C joined to the assembly a faces another independent solid heat conductive material C. That is, the heat generating body A, the solid heat conductive material C, and the assembly a are arranged and laminated in this order to form a laminate. Next, the two solid heat conductive materials C in the laminate are melted and then solidified. By overlapping and using the solid heat conductive material C joined to the assembly a and another independent solid heat conductive material C, the thickness of the assembly can be increased and the joining force can be improved. At this time, in the state where the solid heat conductive material C is melted, a force can be applied and pressed from the side of the assembly a, or from the side of the heat generating body A, or from both the side of the assembly a and the side of the heat generating body A toward the solid heat conductive material C to form an assembly. That is, the manufacturing method of the assembly having the combination of step a1 and step c1 can join the heat generating body A and the heat dissipation component B using two solid heat conductive materials C.

[0158] In addition, as another example, a combination of step b1 and step c1 can be cited.

[0159] For example, in step c1, instead of the heat generating body, an assembly b obtained by joining the solid heat conductive material to the heat generating body in step b1 is arranged. At this time, the solid heat conductive material joined to the assembly b faces another independent solid heat conductive material. That is, the assembly b, the solid heat conductive material, and the heat dissipation component are arranged and laminated in this order to form a laminate. Next, the two solid heat conductive materials in the laminate are melted and then solidified. At this time, in the state where the solid heat conductive material is melted, a force can be applied and pressed from the side of the heat dissipation component, or from the side of the assembly b, or from both the side of the heat dissipation component and the side of the assembly b toward the solid heat conductive material to form an assembly. That is, the manufacturing method of the assembly having the combination of step b1 and step c1 can join the heat generating body and the heat dissipation component using two solid heat conductive materials.

[0160] 《Melting and Solidification》

[0161] In the above methods a to c, as a method for melting the solid heat conductive material, at least one method selected from contact heating, hot air heating, hot pressing, hot plate welding, infrared heating, ultrasonic welding, vibration welding, and high-frequency induction welding can be cited.

[0162] Among them, from the viewpoints of ease of manufacturing and shortening the joining process, hot pressing, ultrasonic welding, and high-frequency induction welding are preferred.

[0163] There are no particular restrictions on the conditions for performing hot pressing.

[0164] The heating temperature in hot pressing is preferably 100°C to 400°C, more preferably 120°C to 350°C, and still more preferably 150°C to 300°C. By heating at 100°C to 400°C, the solid heat-conducting material can be deformed and melted efficiently, and can be effectively wetted and spread on the joint surface, so a high joint strength can be obtained.

[0165] The pressing force in hot pressing is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and still more preferably 0.2 to 5 MPa. If within this pressure range, the solid heat-conducting material can be deformed efficiently and can be effectively wetted and spread on the joint surface, so a high joint strength can be obtained.

[0166] For example, the above joint can be carried out by melting and then solidifying the solid heat-conducting material under a heating temperature of 100 to 400°C and a pressure of 0.01 to 20 MPa.

[0167] Regarding the conditions for ultrasonic welding, when the heating element A and / or the heat dissipation component A' and the heat dissipation component B or the heat dissipation component B' are made of resin, there are no particular limitations as long as the conditions can melt at least a part of these resins and the solid heat-conducting material.

[0168] For example, the transmission frequency is preferably 10 to 70 kHz, more preferably 15 to 40 kHz.

[0169] From the viewpoints of joint property and appearance, the ultrasonic application time is preferably 0.1 to 3 seconds, more preferably 0.2 to 2 seconds.

[0170] When applying ultrasonic waves, when pressing the heating element A and / or the heat dissipation component A' and the heat dissipation component B or the heat dissipation component B', the pressing force is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and still more preferably 0.2 to 5 MPa. If within this pressure range, the solid heat-conducting material can be deformed efficiently and can be effectively wetted and spread on the joint surface, so a high joint strength can be obtained.

[0171] Regarding the conditions for high-frequency induction welding, when the heating element A and / or the heat dissipation component A' and the heat dissipation component B or the heat dissipation component B' are made of metal, there are no particular limitations as long as the conditions can heat and melt these metals.

[0172] For example, the oscillation frequency can be in the range of 1 to 1500 kHz. It can be adjusted to an appropriate oscillation frequency according to the size and type of the heating element A and / or the heat dissipation component A' and the heat dissipation component B or the heat dissipation component B'.

[0173] The output can be in the range of 100 to 5000 W.

[0174] The oscillation time can be adjusted accordingly according to the sizes and types of the heating element A and / or the heat dissipation component A' and the heat dissipation component B or the heat dissipation component B'. For example, it is preferably 1.0 to 10.0 seconds, and more preferably 1.5 to 8.0 seconds.

[0175] As a method for solidifying the molten solid heat conductive material, a method of cooling at room temperature or a method of cooling using a cooling device can be cited. In addition, the so-called "room temperature" refers to the general room temperature within the range of 5 to 30°C. Among them, from the viewpoint of ease of manufacture, a method of cooling at room temperature is preferred.

[0176] In addition, the so-called "solidification" in this specification means being solid at room temperature, that is, having no fluidity in an unpressurized state at 23°C.

[0177] The bonding in the a-c methods is all carried out by utilizing the phase change (solid-liquid-solid) of the solid heat conductive material and does not involve chemical reactions. Therefore, compared with the conventional methods involving chemical reactions, the bonding can be completed in a short time.

[0178] Examples

[0179] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0180] <Substrate>

[0181] The following substrates are used.

[0182] "Substrate A"

[0183] Aluminum (A6061, 25×100×1.6 mm thick. The surface is wiped and degreased with methyl ethyl ketone)

[0184] "Substrate B"

[0185] Aluminum (A6061, 25×100×1.6 mm thick. The surface is wiped and degreased with methyl ethyl ketone)

[0186] <Weight average molecular weight of the base resin used in the production of the solid heat conductive material>

[0187] The weight average molecular weight, heat of fusion, glass transition temperature, melting point, and epoxy equivalent of the base resin used in the production of the solid heat conductive material are determined as follows.

[0188] (Weight average molecular weight)

[0189] The base resin is dissolved in tetrahydrofuran, and measured using Prominence 501 (manufactured by Showa Science Co., Ltd., detector: Shodex (registered trademark) RI-501 (manufactured by Showa Denko K.K.)) under the following conditions.

[0190] Column: LF-804, manufactured by Showa Denko K.K., 2 pieces

[0191] Column temperature: 40 °C

[0192] Sample: 0.4 mass% tetrahydrofuran solution of resin

[0193] Flow rate: 1 ml / min

[0194] Eluent: Tetrahydrofuran

[0195] Calibration method: By conversion with standard polystyrene

[0196] (Heat of fusion, melting point)

[0197] Weigh 2 - 10 mg of the base resin and place it in an aluminum pan. Using DSC (DSC8231 manufactured by Rigaku Corporation), heat from 23 °C to 200 °C at a rate of 10 °C / min to obtain a DSC curve. Calculate the heat of fusion based on the endothermic peak area during melting in the DSC curve and the weighed value. Set the peak temperature during melting as the melting point. However, when no melting peak can be obtained or the heat of fusion is 15 J / g or less, set the temperature obtained by adding 70 °C to the glass transition temperature as the melting point.

[0198] (Glass transition temperature Tg)

[0199] Regarding the glass transition temperature, after heating to 200 °C in the DSC, cool to 40 °C or lower, and then heat to 200 °C again. Set the temperature at which the DSC curve starts to decline during the second cycle as the glass transition temperature.

[0200] (Epoxy equivalent)

[0201] Determined according to JIS K - 7236:2001 and converted to a value based on the resin solid content. And in the case of a simple mixture without accompanying reactions, calculate according to each epoxy equivalent and content.

[0202] <Example 1>

[0203] For Phenotote (registered trademark) YP - 007A30 (a cyclohexanone solution of phenoxy resin, solid content 30 mass%, manufactured by Nippon Steel Chemical & Material Co., Ltd.), use a rotation-revolution mixer to mix spherical alumina CB - A20S (manufactured by Showa Denko K.K., average particle diameter d50 = 21 μm) according to the formulation in Table 1 - 1 to obtain a paste resin composition. The volume% of the filler ("filler amount (vol%)" in Table 1 - 1) is calculated based on the addition amount at 25 °C. Specifically, for the mass% of the filler, calculate based on the specific gravity of the components other than the filler and the true specific gravity of the filler using the aforementioned (Equation 1).

[0204] The paste resin composition was coated on a PET film subjected to a release treatment using a bar coater, dried at 160°C for 2 hours, and then passed through a hot roll at 180°C 20 times to extrude the air in the coating film, thereby obtaining a film-like solid thermal conductive material sample (hereinafter referred to as SP) 1.

[0205] The solid thermal conductive material SP1 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size 25×100×1.6 mm), and a pressure of 3 MPa was applied at 200°C using a hot press for 10 minutes to melt the solid thermal conductive material SP1. Subsequently, the pressure was released and it was allowed to cool, thereby curing the solid thermal conductive material SP1 to produce a bonded body.

[0206] <Example 2>

[0207] A film-like solid thermal conductive material SP2 was obtained in the same manner as in Example 1, except that the formulation of Phenotote (registered trademark) YP-007A30 (manufactured by Nippon Steel Chemical & Material Co., Ltd., cyclohexanone solution of phenoxy resin, solid content 30% by mass) and spherical alumina CB-A20S was changed to that shown in Table 1.

[0208] A bonded body was produced in the same manner as in Example 1, except that the solid thermal conductive material SP2 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size 25×100×1.6 mm).

[0209] <Example 3>

[0210] A film-like solid thermal conductive material SP3 was obtained in the same manner as in Example 1, except that the formulation of Phenotote (registered trademark) YP-007A30 (manufactured by Nippon Steel Chemical & Material Co., Ltd., cyclohexanone solution of phenoxy resin, solid content 30% by mass) and spherical alumina CB-A20S was changed to that shown in Table 1.

[0211] A bonded body was produced in the same manner as in Example 1, except that the solid thermal conductive material SP3 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size 25×100×1.6 mm).

[0212] <Example 4>

[0213] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 20 g of Phenotote (registered trademark) YP-50S (manufactured by Nippon Steel Chemical & Material Co., Ltd., phenoxy resin, weight-average molecular weight of about 50,000) and 80 g of cyclohexanone were added. The temperature was raised to 60 °C while stirring, and after visually confirming dissolution, it was cooled to 40 °C. The resulting resin solution with a solid content of 20% by mass was used as the base resin solution. Except for this, a film-like solid heat-conductive material SP4 was obtained in the same manner as in Example 1.

[0214] A bonded body was produced in the same manner as in Example 1, except that the solid heat-conductive material SP4 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0215] <Example 5>

[0216] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 1.0 equivalent (203 g) of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, weight-average molecular weight of about 11,000), 1.0 equivalent (12.5 g) of bisphenol S, 2.4 g of triphenylphosphine, and 1,000 g of cyclohexanone were added. The temperature was raised to 100 °C while stirring in a nitrogen atmosphere. After visually confirming dissolution, the temperature was raised to 170 °C, and after reacting at 170 °C for 6.5 hours, it was cooled to 40 °C. The resulting resin solution with a solid content of 20% by mass was used as the base resin solution. Except for this, a film-like solid heat-conductive material SP5 was obtained in the same manner as in Example 1.

[0217] A bonded body was produced in the same manner as in Example 1, except that the solid heat-conductive material SP5 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0218] <Example 6>

[0219] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 1.0 equivalent (203 g) of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, weight average molecular weight of about 11,000), 1.0 equivalent (12.5 g) of bisphenol S, 2.4 g of triphenylphosphine, and 1,000 g of cyclohexanone were added. While stirring in a nitrogen atmosphere, the temperature was raised to 100°C. After visually confirming dissolution, it was cooled to 40°C to obtain a base resin solution with a solid content of 20% by mass. The spherical alumina CB-A20S (manufactured by Showa Denko K.K., average particle diameter d50 = 21 μm) was mixed with the base resin solution using a rotation-revolution mixer according to the formulation in Table 1 to obtain a paste. The paste was coated on a PET film that had been subjected to a release treatment using a bar coater, and dried by heating at 160°C for 2 hours to polymerize the epoxy resin and bisphenol S. Then, it was passed through a hot roll at 180°C 20 times to extrude the air in the coating film, thereby obtaining a film-like solid thermal conductive material SP6.

[0220] A bonded body was produced in the same manner as in Example 1, except that the solid thermal conductive material SP6 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0221] <Example 7>

[0222] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 203 g of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, weight average molecular weight of about 11,000) and 1,000 g of cyclohexanone were added. While stirring in a nitrogen atmosphere, the temperature was raised to 100°C. After visually confirming dissolution, it was cooled to 40°C, and the obtained base resin solution with a solid content of 20% by mass was used as the base resin solution. Otherwise, a film-like solid thermal conductive material SP7 was obtained in the same manner as in Example 1.

[0223] A bonded body was produced in the same manner as in Example 1, except that the solid thermal conductive material SP7 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0224] <Example 8>

[0225] The crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) was pulverized and evenly sprinkled on the film of Example 3 (solid heat-conducting material SP3) until the alumina content reached 65% by mass, pressed with a vise, and heated to 50 °C to obtain a film-shaped solid heat-conducting material SP8. A bonded body was produced in the same manner as in Example 1, except that the solid heat-conducting material SP8 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0226] <Example 9>

[0227] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 1.0 equivalent (203 g) of jER (registered trademark) 1007 (a bisphenol A-type epoxy resin manufactured by Mitsubishi Chemical Corporation, with a weight-average molecular weight of approximately 11,000), 1.0 equivalent (12.5 g) of bisphenol S, 2.4 g of triphenylphosphine, and 1,000 g of cyclohexanone were added. While stirring, the temperature was raised to 100 °C in a nitrogen atmosphere. After visually confirming dissolution, it was cooled to 40 °C to obtain a base resin solution with a solid content of 20% by mass. Silver particles (particle size 1.5 μm) were mixed with the base resin solution according to the formulation in Table 1 to obtain a resin composition. The resin composition was coated on a PET film that had been subjected to a release treatment using a bar coater, heated at 160 °C for 2 hours to dry the solvent and polymerize the epoxy resin and bisphenol S, and then passed through a hot roll at 180 °C 20 times to extrude the air in the coating film, thereby obtaining a film-shaped solid heat-conducting material SP9. A bonded body was produced in the same manner as in Example 1, except that the solid heat-conducting material SP9 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0228] <Example 10>

[0229] 57 parts by mass of a paste resin composition obtained by mixing spherical alumina CB-A20S with YP-007A30 in the same manner as in Example 1 was mixed with 43 parts by mass of a paste resin composition (mixed in a 25% by mass resin solution obtained by dissolving a polyamide-based crystalline hot-melt adhesive TY-863H1 in THF so that the spherical alumina CB-A20S became 64% by volume) using a rotary mixer. Using the resulting resin composition, a film-shaped solid heat-conducting material SP10 was obtained in the same manner as in Example 1, except for this. A bonded body was produced in the same manner as in Example 1, except that the solid heat-conducting material SP10 cut into a size of 25 × 12.5 mm was sandwiched between substrates A and B (size 25 × 100 × 1.6 mm).

[0230] <Example 11>

[0231] A film-like solid heat-conductive material SP11 was obtained in the same manner as in Example 7, except that jER1004 (a bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation, with a weight average molecular weight of about 5000) was used instead of jER1007.

[0232] A bonded body was produced in the same manner as in Example 1, except that the solid heat-conductive material SP11 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size: 25×100×1.6 mm).

[0233] <Comparative Example 1>

[0234] A sample (hereinafter referred to as CSP) 1 for comparison of a film-like solid heat-conductive material was obtained in the same manner as in Example 1, except that a resin solution with a concentration of 25% wt in which a polyamide-based crystalline hot-melt adhesive TY-863H1 was dissolved in THF was used as the base resin solution.

[0235] A bonded body was produced in the same manner as in Example 1, except that the solid heat-conductive material CSP1 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size: 25×100×1.6 mm).

[0236] <Comparative Example 2>

[0237] Spherical alumina CB-A20S (manufactured by Showa Denko K.K., average particle diameter d50 = 21 μm) was added to a crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) so as to be 46% by volume, and the mixture was mixed using a rotation-revolution mixer to obtain a paste. The paste was sandwiched between a PET film that had been subjected to a release treatment and pressed to obtain a film-like solid heat-conductive material CSP2 for comparison.

[0238] A bonded body was produced in the same manner as in Example 1, except that the solid heat-conductive material CSP2 cut into a size of 25×12.5 mm was sandwiched between substrates A and B (size: 25×100×1.6 mm).

[0239] <Comparative Example 3>

[0240] 100 g of epoxy resin jER1007, 6.2 g of bisphenol S, and 0.4 g of triethylamine were dissolved in 197 g of acetone to obtain a composition (A1).

[0241] In addition, 100 g of an epoxy resin NC-3000 having a biphenyl skeleton, 91.9 g of a phenolic compound TAM-005 having an imidazolidinone skeleton, and 1.54 g of triethylamine were dissolved in 356.5 g of acetone to obtain a composition (B2).

[0242] In a resin composition prepared by blending the composition (A1) and the composition (B1) such that the mass ratio excluding acetone is 40 / 60, the spherical alumina CB-A20S blended is changed as shown in Table 1. Otherwise, a film-like solid heat-conductive material CSP3 is obtained in the same manner as in Example 1. A bonded body is produced in the same manner as in Example 1, except that the solid heat-conductive material CSP3 cut into a size of 25×12.5 mm is sandwiched between substrates A and B (size 25×100×1.6 mm).

[0243] <Comparative Example 4>

[0244] A film-like solid heat-conductive material for comparison CSP4 is obtained in the same manner as in Example 1, except that spherical alumina CB-A20S is not mixed.

[0245] [Thermal conductivity]

[0246] The thermal conductivities of the solid heat-conductive materials obtained in Examples 1 to 11 and Comparative Examples 1 to 4 were evaluated by the laser flash method using the following formula. The evaluation results are shown in Tables 1-1 and 1-2.

[0247] Thermal conductivity = Thermal diffusivity × Specific heat capacity × Density

[0248] The "thermal diffusivity", "specific heat capacity", and "density" in the above formula are obtained by the following methods, respectively.

[0249] Thermal diffusivity: A disk with a diameter of 10 mm is cut out from a flat plate of the thermally conductive resin composition, and the thermal diffusivity in the thickness direction of the disk is measured at 20°C using a laser flash apparatus LaserFlash TC-7000 (manufactured by Vacuum Physics Co., Ltd.).

[0250] Specific heat capacity: The specific heat capacity of the powder of the thermally conductive resin composition is measured in accordance with JIS K 7123:1987 using a differential scanning calorimeter DSC7 (manufactured by PerkinElmer). Specifically, about 10 mg of the thermally conductive resin composition is sealed in an aluminum pan. The sample pan and the empty pan are set on a holder. After maintaining at 0°C for 15 minutes, the temperature is raised to 50°C at a heating rate of 10°C / min to obtain the DSC curve of the thermally conductive resin composition. With the same temperature curve, the DSC curve of about 10 mg of the reference substance α-alumina is obtained. The specific heat capacity of the thermally conductive resin composition is evaluated based on the DSC curves of the thermally conductive resin composition and α-alumina.

[0251] Density: A test piece of 50 mm×50 mm is cut out from a flat plate of the thermally conductive resin composition and measured according to JIS K7112:1999 using a DENSIMETER (manufactured by Toyo Seiki Seisaku-sho, Ltd.).

[0252] [Shearing bond strength]

[0253] Using the bonded bodies obtained in Examples 1 to 11 and Comparative Examples 1 to 4, after leaving them standing for 30 minutes or more at the measurement temperature (23°C or 80°C), according to ISO19095, a tensile testing machine (Universal Testing Machine Autograph “AG-Xplus” (manufactured by Shimadzu Corporation); load cell 10 kN, tensile speed 10 mm / min) was used to conduct a tensile shear bond strength test in an environment of 23°C and 80°C to measure the bonding strength. The measurement results are shown in Tables 1-1 and 1-2.

[0254] [Conformability of uneven surfaces]

[0255] After the test of the shearing bond strength of the bonded bodies obtained in Examples 1 to 11 and Comparative Examples 1 to 4, the bonding surface was observed. If there was no part of the bonded body that did not conform to the base material, it was regarded as good (OK), and if there was a non-conforming part, it was regarded as inappropriate (poor). The evaluation results are shown in Tables 1-1 and 1-2.

[0256] [Bonding process time]

[0257] The bonding process time was measured as follows.

[0258] Taking the time when at least any of the base materials constituting the bonded body came into contact with the bonding agent as the starting point and the completion of the production of the bonded body as the end point, the time from the starting point to the end point was measured. Regarding the heating / pressurizing time, the heating / pressurizing times of the three types of bonded bodies were averaged. The measurement results are shown in Tables 1-1 and 1-2.

[0259] [Recyclability]

[0260] After heating the bonded body on a hot plate at 200°C for 1 minute, it was judged whether it could be easily peeled off with a force of 1 N or less. If it could be peeled off, it was regarded as good (OK), and if it could not be peeled off, it was regarded as inappropriate (poor). The evaluation results are shown in Tables 1-1 and 1-2.

[0261] [Repairability]

[0262] After the test of the shearing bond strength in an environment of 23°C, substrate A was placed on substrate B in each test piece after the bonding surface was fractured (a layer of bonding solid remained on the surface of substrate A or B or both), and a bonded body was produced in the same manner as in Example 1 to obtain a repaired bonded body. The shearing bond strength of the repaired bonded body at 23°C was measured in the same manner as the test method. If it was 80% or more of the first shearing bond strength, it was regarded as good, and if it was less than 80%, it was regarded as inappropriate. The evaluation results are shown in Tables 1-1 and 1-2.

[0263] [Evaluation of exposure time (opentime)]

[0264] Using the conjugate for exposure time evaluation, the tensile shear joint strength test is carried out at 23°C. Compared with the test pieces prepared by the methods of the above-mentioned examples and comparative examples, if the shear joint force is 80% or more, it is regarded as good, and if it is less than 80%, it is regarded as poor. That the exposure time evaluation is good means that the exposure time is long and the convenience is excellent.

[0265] [Table 1-1]

[0266]

[0267] [Table 1-2]

[0268]

[0269] As shown in Table 1-1, the solid heat-conducting material of the present invention has high thermal conductivity and bonding strength. In addition to this characteristic, the solid heat-conducting material of the present invention also has the following characteristics.

[0270] Since the solid heat-conducting material of the present invention is thermoplastic and can reversibly repeat softening / melting and curing, it can be stored as a solid before being assembled into an electronic device. After becoming a liquid at the assembly site, it can be assembled as a solid. Since it can be stored as a solid before being assembled into an electronic device, no special technique is required for storage and assembly operations, and the adaptability to existing production lines is excellent. Therefore, according to the present invention, the problem of "low adaptability to production lines" which is a drawback of conventional liquid TIMs can be overcome.

[0271] Since the solid heat-conducting material of the present invention contains an amorphous thermoplastic resin, it melts at the assembly site, can follow and conform to the unevenness of complex shapes, and then cures. Therefore, as shown in Table 1-1 above, the unevenness conformability is excellent and the adaptability to various designs is high. Therefore, according to the present invention, the problem of "low adaptability to designs" which is a drawback of conventional sheet-like TIMs can be overcome.

[0272] Since the solid heat-conducting material of the present invention contains an amorphous thermoplastic resin, it can reversibly repeat softening / melting and curing, so there is no pumping out, it is not easy to generate holes, and the performance degradation caused by long-term use and repeated use can be avoided. Therefore, according to the present invention, the problem of "performance degradation caused by long-term use and repeated use" which is a drawback of conventional thermal greases can be overcome.

[0273] Industrial applicability

[0274] The solid heat-conducting material of the present invention is applicable to the use of electrothermal components used in electronic devices. The solid heat-conducting material of the present invention can also be used as a film-like adhesive material for semiconductor chips. For example, it can be used as a diebonding film, and in this case, it can also be used as a dicing / diebonding integrated film laminated with a dicing tape.

[0275] Explanation of Reference Numerals

[0276] A: Heating element

[0277] A’: Heat dissipation component

[0278] B: Heat dissipation component

[0279] B’: Heat dissipation component

[0280] C: Solid heat-conducting material

Claims

1. A solid heat-conducting material comprising an amorphous thermoplastic resin and a heat-dissipating filler.

2. The solid heat-conducting material according to claim 1, wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less.

3. The solid heat-conducting material according to claim 2, wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin.

4. The solid heat-conducting material according to claim 3, wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having an epoxy equivalent of 1600 or more, or an amorphous thermoplastic resin free of an epoxy group.

5. The solid heat-conducting material according to claim 1, wherein the content of the heat-dissipating filler is 30 to 95% by volume.

6. The solid heat-conducting material according to claim 1, wherein the heat-dissipating filler is at least one selected from silver, alumina, magnesia, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, silica, carbon black, carbon nanofibers, carbon nanotubes, silicon carbide, and silicon nitride.

7. An electronic device comprising a heat-conducting layer formed of a solid heat-conducting material, the solid heat-conducting material comprising an amorphous thermoplastic resin and a heat-dissipating filler.

8. The electronic device according to claim 7, wherein the heat-conducting layer present between a heat-generating body and a heat-dissipating member, or the heat-conducting layer present between heat-dissipating members, is formed by melting and curing the solid heat-conducting material between the heat-generating body and the heat-dissipating member, or between the heat-dissipating members.

9. The electronic device according to claim 7 or 8, wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having a heat of fusion of 15 J / g or less.

10. The electronic device according to claim 9, wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin.

11. The electronic device according to claim 10, wherein the amorphous thermoplastic resin is an amorphous thermoplastic resin having an epoxy equivalent of 1600 or more, or an amorphous thermoplastic resin free of an epoxy group.

12. The electronic device according to claim 7 or 8, wherein the content of the heat-dissipating filler is 30 to 95% by volume.

13. The electronic device according to claim 7 or 8, wherein the heat-dissipating filler is at least one selected from silver, alumina, magnesia, aluminum hydroxide, magnesium hydroxide, aluminum nitride, boron nitride, silica, carbon black, carbon nanofibers, carbon nanotubes, silicon carbide, and silicon nitride.

14. The electronic device according to claim 8, wherein the melting is performed by heating and pressurizing the solid heat-conducting material.

15. The electronic device according to claim 14, wherein the heating and pressurizing are performed under conditions of 100 to 400 °C and 0.01 to 20 MPa.

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