Resin sheet

Abstract

To provide a thermosetting resin composition which can be used for producing a thermally conductive sheet having high thermal conductivity.SOLUTION: A thermosetting resin composition comprising (A) an epoxy resin, (B) a thermosetting resin (excluding the epoxy resin (A)), (C) a phenoxy resin, and (D) a thermally conductive filler, wherein the phenoxy resin (C) is a phenoxy resin obtained by reacting a bifunctional epoxy compound (c1) having two epoxy groups, a polyfunctional epoxy compound (c2) having three or more epoxy groups, and a polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting resin composition, a resin sheet made of the thermosetting resin composition, an electronic device comprising a cured product of the resin sheet as a thermally conductive sheet, a metal base substrate comprising a cured product of the resin sheet, and an electronic device comprising the metal base substrate. [Background technology]

[0002] With the increasing integration of semiconductors and the rapid improvement in the processing power of electronic devices, electronic components with high processing power generate a lot of heat. Therefore, heat countermeasures to effectively dissipate heat from electronic components to the outside have become an extremely important issue. As a heat dissipation measure, thermally conductive members made of heat dissipating materials such as metals, ceramics, and polymer compositions are used in heat dissipation components such as printed wiring boards, semiconductor packages, housings, heat pipes, heat sinks, and heat diffusion plates.

[0003] Among these heat dissipation members, thermally conductive epoxy resin molded articles molded from epoxy resin compositions are excellent in electrical insulation properties, mechanical properties, heat resistance, chemical resistance, adhesive properties, etc., and are therefore widely used mainly in the electrical and electronic fields as castings, laminates, sealing materials, thermally conductive sheets, adhesives, etc.

[0004] As an example of this type of technology, Patent Document 1 proposes a thermally conductive epoxy resin composition and a molded product thereof, in which bisphenol A epoxy resin is blended with scaly or spherical boron nitride particles as thermally conductive particles. It has also been proposed to improve the thermal conductivity and heat resistance of the epoxy resin itself (see, for example, Patent Document 2). Patent Document 2 proposes an insulating composition with improved thermal conductivity by polymerizing a liquid crystalline epoxy resin having a mesogenic group. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-193504 [Patent Document 2] Patent Application No. 2004-331811 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as a result of investigations by the present inventors, it has been found that conventional resin compositions have room for further improvement in terms of thermal conductivity. [Means for solving the problem]

[0007] The present invention has been made in view of the above problems, and the inventors have found that a novel phenoxy resin having a specific structure has high thermal conductivity, and have completed the present invention.

[0008] According to the present invention, (A) an epoxy resin; (B) a thermosetting resin (excluding the epoxy resin (A)); (C) phenoxy resin; (D) a thermally conductive filler, The phenoxy resin (C) is a bifunctional epoxy compound (c1) having two epoxy groups; a multifunctional epoxy compound (c2) having three or more epoxy groups; a polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups, The bifunctional epoxy compound (c1) includes a compound represented by formula (d-EP): [ka] X in the formula (d-EP) is a divalent organic group having a mesogenic skeleton represented by formula (2), [ka] In equation (2), R 1 ~R8 are independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, * represents the linking position, The polyfunctional phenol compound (c3) includes at least one selected from the compounds represented by formulas (p1) to (p17), [ka] [ka] [ka] [ka] [ka] [ka] In the formulas (p1) to (p17), R independently represents a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 6 carbon atoms.

[0009] According to the present invention, there is also provided a resin sheet made from the above-mentioned thermosetting resin composition.

[0010] Further, according to the present invention, A heat-generating member; A heat dissipation member; a thermally conductive sheet provided between the heat-generating component and the heat-dissipating component, The electronic device is provided, wherein the thermally conductive sheet is made of a cured product of the resin sheet.

[0011] Further, according to the present invention, A metal substrate; a thermally conductive sheet; A metal base substrate comprising, in this order, The thermally conductive sheet is a metal base substrate made of the cured resin sheet.

[0012] Furthermore, the present invention provides an electronic device comprising the above metal base substrate. [Effects of the Invention]

[0013] According to the present invention, there is provided a thermosetting resin composition that can be used to produce a thermally conductive sheet having high thermal conductivity. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view schematically illustrating a structure of a metal base substrate according to an embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing the configuration of an electronic device using a metal base substrate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and their description will be omitted where appropriate. Furthermore, unless otherwise specified, "~" indicates "above" to "below."

[0016] [Thermosetting resin composition] The thermosetting resin composition of the present embodiment contains the following components (A) to (D). (A) an epoxy resin; (B) a thermosetting resin (excluding the epoxy resin (A)); (C) phenoxy resin; (D) Thermally conductive filler. The thermosetting resin composition of the present embodiment has the above composition and therefore has high thermal conductivity, and can be suitably used, for example, as a thermally conductive sheet for electronic devices.

[0017] The components used in the thermosetting resin composition of this embodiment will be described below.

[0018] (Epoxy resin (A)) The thermosetting resin composition of this embodiment contains an epoxy resin (A). Examples of the epoxy resin (A) include glycidyl ethers of bisphenol A, F, S, AD, etc., hydrogenated bisphenol A, phenol novolac, cresol novolac, bisphenol A novolac, naphthalene, biphenol, dihydroxypentadiene, triphenylmethane, phenol novolac, cresol novolac, and hydroquinone, and at least one of these can be used. From the viewpoint of the effects of the present invention, the epoxy resin (A) preferably contains at least one selected from naphthalene-type glycidyl ethers, biphenol-type glycidyl ethers, dihydroxypentadiene-type glycidyl ethers, and hydroquinone-type glycidyl ethers.

[0019] The epoxy resin (A) may preferably contain an epoxy resin containing a mesogenic skeleton, which can further enhance the thermal conductivity (heat dissipation) of the cured resin. It is believed that epoxy resins containing a mesogenic skeleton form a higher-order structure (liquid crystal phase or crystalline phase) due to the mesogenic skeleton when cured. It is believed that heat is transferred through this higher-order structure, further enhancing thermal conductivity (heat dissipation). The presence of the higher-order structure in the cured product can be confirmed by observation with a polarizing microscope.

[0020] The mesogenic skeleton may be any skeleton that facilitates the development of liquid crystallinity or crystallinity through intermolecular interactions. The mesogenic skeleton preferably includes a conjugated structure. Specific examples of the mesogenic skeleton include a biphenyl skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, a stilbene skeleton, a naphthalene skeleton, an anthracene skeleton, a chalcone skeleton, and a phenanthrene skeleton.

[0021] The epoxy resin (A) particularly preferably contains a condensed polycyclic aromatic hydrocarbon skeleton, and particularly preferably contains a naphthalene skeleton.

[0022] For example, in the case of a biphenyl skeleton (-CH-CH-), the central carbon-carbon single bond in the structure may "rotate" due to thermal motion at high temperatures, potentially resulting in a decrease in liquid crystallinity. Similarly, in the case of a phenylbenzoate skeleton (-CH-COO-CH-), the ester bond may rotate at high temperatures. However, in principle, such rotation does not cause a decrease in liquid crystallinity in a condensed polycyclic aromatic hydrocarbon skeleton such as a naphthalene skeleton. In other words, the inclusion of a condensed polycyclic aromatic hydrocarbon skeleton in an epoxy resin can further improve the heat dissipation properties of the resulting cured resin in high-temperature environments.

[0023] Furthermore, by employing a naphthalene skeleton as the polycyclic aromatic hydrocarbon skeleton, the epoxy resin can be prevented from becoming too rigid while still achieving the above-mentioned advantages. This is because the naphthalene skeleton is relatively small for a mesogenic skeleton. The fact that the epoxy resin does not become too rigid is advantageous in that stress during curing of the thermosetting resin composition of this embodiment is more easily alleviated, thereby preventing cracks and the like.

[0024] The epoxy resin (A) preferably contains a di- or higher functional epoxy resin. In other words, it is preferable that one epoxy resin molecule contains two or more epoxy groups. The number of functional groups in the epoxy resin is preferably 2 to 6, and more preferably 2 to 4. From the viewpoint of the effects of the present invention, the epoxy resin (A) in this embodiment preferably contains at least one epoxy resin selected from compounds represented by the following formula:

[0025] [ka]

[0026] The epoxy equivalent of the epoxy resin (A) is, for example, 100 to 200 g / eq, preferably 105 to 190 g / eq, and more preferably 110 to 180 g / eq. By using an epoxy resin with an appropriate epoxy equivalent, it is possible to control the curability and optimize the physical properties of the cured product.

[0027] In one embodiment, the epoxy resin (A) preferably further contains another epoxy resin that is liquid or semi-solid at room temperature (23° C.). Specifically, it is preferred that a part or all of the epoxy resin is liquid or semi-solid at 23° C. By using a liquid or semi-solid epoxy resin, it becomes easier to form a cured product in a desired shape.

[0028] In one embodiment, the epoxy resin (A) preferably contains a combination of an epoxy resin that is liquid at room temperature and an epoxy resin that is semi-solid or solid at room temperature, which improves the moldability of the resulting thermosetting resin composition.

[0029] The epoxy resin (A) is, for example, 5% by mass to 40% by mass, preferably 7% by mass to 35% by mass, and more preferably 10% by mass to 30% by mass, relative to the resin component (100% by mass) of the thermosetting resin composition excluding the thermally conductive particles (D). This ensures sufficient curability, and allows the production of a resin sheet with excellent thermal conductivity and insulation.

[0030] (Thermosetting resin (B)) The thermosetting resin composition of this embodiment contains a thermosetting resin (B), which does not contain the above-mentioned epoxy resin (A). Examples of the thermosetting resin (B) include thermosetting compounds containing a mesogenic structure (mesogenic skeleton) in the molecule and thermosetting compounds not containing a mesogenic structure in the molecule.

[0031] Examples of the thermosetting resin (B) include cyanate resins, maleimide resins, phenolic resins, benzoxazine resins, polyimide resins, unsaturated polyester resins, melamine resins, silicone resins, acrylic resins, and phenol derivatives and derivatives thereof, and at least one of these may be included.

[0032] In this embodiment, the thermosetting resin (B) preferably contains at least one selected from cyanate resins, bismaleimide resins, phenolic resins, and benzoxazine resins, and more preferably contains a cyanate resin. These thermosetting resins can be any monomer, oligomer, or polymer having two or more reactive functional groups in one molecule, and there are no particular limitations on the molecular weight or molecular structure.

[0033] <Cyanate resin> As the cyanate resin, any known cyanate resin can be used as long as it achieves the effects of the present invention. The cyanate resin can include one or more selected from the group consisting of novolac cyanate resins; bisphenol cyanate resins such as bisphenol A cyanate resins, bisphenol E cyanate resins, and tetramethylbisphenol F cyanate resins; naphthol aralkyl cyanate resins obtained by reacting naphthol aralkyl phenol resins with cyanogen halides; dicyclopentadiene cyanate resins; and biphenylene skeleton-containing phenol aralkyl cyanate resins. Among these, from the viewpoint of the effects of the present invention, it is more preferable to include at least one of novolac cyanate resins and naphthol aralkyl cyanate resins, and it is particularly preferable to include novolac cyanate resins.

[0034] As the novolac type cyanate resin, for example, one represented by the following general formula (I) can be used.

[0035] [ka]

[0036] The average repeating unit number n of the novolac cyanate resin represented by general formula (I) is any integer. The average repeating unit number n is not particularly limited, but is preferably 1 or more, more preferably 2 or more. When the average repeating unit number n is equal to or greater than the above-mentioned lower limit, the heat resistance of the novolac cyanate resin is improved, and the elimination and volatilization of oligomers upon heating can be further suppressed. Furthermore, the average repeating unit number n is not particularly limited, but is preferably 10 or less, more preferably 7 or less. When n is equal to or less than the above-mentioned upper limit, the melt viscosity can be suppressed from increasing, and the moldability of the resin sheet can be improved.

[0037] Furthermore, naphthol aralkyl cyanate resins represented by the following general formula (II) are also suitable as cyanate resins. The naphthol aralkyl cyanate resins represented by the following general formula (II) are obtained by condensing a naphthol aralkyl phenolic resin obtained by reacting naphthols such as α-naphthol or β-naphthol with p-xylylene glycol, α,α'-dimethoxy-p-xylene, 1,4-di(2-hydroxy-2-propyl)benzene, or the like, with a cyanogen halide. The repeating unit n in general formula (II) is preferably an integer of 10 or less. When the repeating unit n is 10 or less, a more uniform resin sheet can be obtained. Furthermore, intramolecular polymerization is less likely to occur during synthesis, improving separation during washing with water and tending to prevent a decrease in yield.

[0038] [ka]

[0039] In the above general formula (II), R each independently represents a hydrogen atom or a methyl group, and n represents an integer of 1 or more and 10 or less.

[0040] The cyanate resin is, for example, 10% by mass to 70% by mass, preferably 15% by mass to 60% by mass, and more preferably 20% by mass to 50% by mass, relative to the resin component (100% by mass) of the thermosetting resin composition excluding the thermally conductive particles (D). This ensures sufficient curability, and allows the production of a resin sheet with even higher thermal conductivity and insulating properties.

[0041] <Maleimide resin> The maleimide resin is preferably, for example, a maleimide resin having at least two maleimide groups in the molecule.

[0042] Examples of maleimide resins having at least two maleimide groups in the molecule include resins having two maleimide groups in the molecule, such as 4,4'-diphenylmethane bismaleimide, m-phenylene bismaleimide, p-phenylene bismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane, 4-methyl-1,3-phenylene bismaleimide, N,N'-ethylene dimaleimide, N,N'-hexamethylene dimaleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethane bismaleimide, and bisphenol A diphenyl ether bismaleimide; and resins having three or more maleimide groups in the molecule, such as biphenylaralkyl maleimide and polyphenylmethane maleimide.

[0043] <Phenol resin> Examples of phenolic resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, and resol-type phenolic resins. One of these may be used alone, or two or more may be used in combination. Among phenolic resins, it is preferable to use phenol novolac resin.

[0044] <Benzoxazine resin> Specific examples of benzoxazine resins include o-cresol aniline type benzoxazine resins, m-cresol aniline type benzoxazine resins, p-cresol aniline type benzoxazine resins, phenol-aniline type benzoxazine resins, phenol-methylamine type benzoxazine resins, phenol-cyclohexylamine type benzoxazine resins, phenol-m-toluidine type benzoxazine resins, phenol-3,5-dimethylaniline type benzoxazine resins, bisphenol A-aniline type benzoxazine resins, bisphenol A-amine type benzoxazine resins, and bisphenol F-aniline type benzoxazine resins. Examples of benzoxazine resins include aniline-type benzoxazine resins, bisphenol S-aniline-type benzoxazine resins, dihydroxydiphenylsulfone-aniline-type benzoxazine resins, dihydroxydiphenylether-aniline-type benzoxazine resins, benzophenone-type benzoxazine resins, biphenyl-type benzoxazine resins, bisphenol AF-aniline-type benzoxazine resins, bisphenol A-methylaniline-type benzoxazine resins, phenol-diaminodiphenylmethane-type benzoxazine resins, triphenylmethane-type benzoxazine resins, and phenolphthalein-type benzoxazine resins.

[0045] From the viewpoint of the effects of the present invention, the content of the thermosetting resin (B) is, for example, preferably 0.1 mass % to 70 mass %, more preferably 0.5 mass % to 65 mass %, and even more preferably 1 mass % to 60 mass %, relative to the resin component (100 mass %) of the thermosetting resin composition not including the thermally conductive particles (D).

[0046] (Phenoxy resin (C)) The thermosetting resin composition of the present embodiment contains a phenoxy resin (C). The phenoxy resin (C) is a bifunctional epoxy compound (c1) having two epoxy groups; a multifunctional epoxy compound (c2) having three or more epoxy groups; and a polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups. More specifically, the phenoxy resin (C) is a phenoxy resin containing structural units derived from a difunctional epoxy compound (c1) having two epoxy groups, structural units derived from a polyfunctional epoxy compound (c2) having three or more epoxy groups, and structural units derived from a polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups.

[0047] The difunctional epoxy compound (c1) constituting the phenoxy resin (C) used in this embodiment includes a compound represented by formula (d-EP).

[0048] [ka]

[0049] X in formula (d-EP) is a divalent organic group having a mesogenic skeleton represented by formula (2).

[0050] [ka]

[0051] In equation (2), R 1 ~R 8 are independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents the linking position.

[0052] The phenoxy resin (C) used in the thermosetting resin composition of the present embodiment contains a structural unit derived from the bifunctional epoxy compound (A) in which X in formula (d-EP) is a mesogenic skeleton represented by formula (2), and thus the cured product thereof has high thermal conductivity.

[0053] Furthermore, the phenoxy resin (C) has a structure represented by the following formula (1), which is obtained by the polymerization reaction between a bifunctional epoxy compound (c1) and a bifunctional polyfunctional phenolic compound (c3), and also has a three-dimensional network structure obtained by the polymerization reaction between a polyfunctional epoxy compound (c2) having three or more epoxy groups and the polyfunctional phenolic compound (c3). This allows the phenoxy resin (C) to have high thermal conductivity and high heat resistance. Each monomer component constituting the phenoxy resin (C) is described below.

[0054] [ka]

[0055] In formula (1), X represents a group derived from the difunctional epoxy compound (c1), and Y represents a group derived from the polyfunctional phenol compound (c3) when it is difunctional.

[0056] In this embodiment, the difunctional epoxy compound (c1) includes a compound represented by the formula (d-EP).

[0057] [ka]

[0058] X in formula (d-EP) is a divalent organic group having a mesogenic skeleton represented by formula (2).

[0059] [ka]

[0060] In equation (2), R 1 ~R8 are independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents the linking position.

[0061] In one embodiment, the group represented by formula (2) which is X in formula (d-EP) is preferably a group in which R1, R4, R5, and R8 are alkyl groups having 1 to 6 carbon atoms, and R2, R3, R6, and R7 are hydrogen atoms. Among these, a group in formula (2) in which R1, R4, R5, and R8 are alkyl groups having 1 carbon atom, and R2, R3, R6, and R7 are hydrogen atoms (referred to as a "tetramethylbiphenyl group") is preferred because it allows the resulting phenoxy resin (C) to have an excellent balance between thermal conductivity and heat resistance.

[0062] In one embodiment, the group represented by formula (2) which is X in formula (d-EP) may be a group in which R1, R4, R5, and R8 are alkyl groups each having one carbon atom, and R2, R3, R6, and R7 are hydrogen atoms (referred to as a "biphenyl group"). By containing such a group, the phenoxy resin (C) has excellent thermal conductivity and heat resistance.

[0063] In one embodiment, X in formula (d-EP) preferably contains a tetramethylbiphenyl group and a biphenyl group. The phenoxy resin (C) containing these groups in combination can have an excellent balance of thermal conductivity and heat resistance.

[0064] In one embodiment, the polyfunctional epoxy compound (c2) having three or more epoxy groups includes at least one selected from a trisphenolmethane type epoxy resin, a naphthalene type epoxy compound, and a triazine type epoxy compound.

[0065] In one embodiment, the polyfunctional epoxy compound (c2) has an epoxy equivalent of 50 to 300 g / eq, preferably 100 to 250 g / eq.

[0066] In one embodiment, the polyfunctional epoxy compound (c2) is a trisphenolmethane-type epoxy resin represented by formula (m1), a naphthalene-type epoxy compound represented by formula (m2) or formula (m3), or a triazine-type epoxy compound represented by formula (m4).

[0067] [ka] [ka]

[0068] In formula (m1), n1 is an integer of 0 to 4, preferably 0 or 1, and more preferably 1. In formulas (m1) to (m3), R 11 ~R 13 are independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 11 ~R 13 are all hydrogen atoms.

[0069] In this embodiment, the polyfunctional phenol compound (c3) is a phenol compound having at least two phenolic hydroxyl groups, preferably a bifunctional phenol compound having two phenolic hydroxyl groups, or a trifunctional phenol compound having three phenolic hydroxyl groups, and specifically includes at least one selected from the compounds represented by formulas (p1) to (p17).

[0070] [ka] [ka] [ka] [ka] [ka] [ka]

[0071] In formulas (p1) to (p17), R independently represents a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 6 carbon atoms, and is preferably a hydrogen atom or a methoxy group. The phenoxy resin (C) used in this embodiment contains structural units derived from compounds represented by formulas (p1) to (p17), and thus a cured product of a resin composition containing the phenoxy resin (C) can have high thermal conductivity. In this embodiment, the polyfunctional phenol compounds having a flavanone skeleton represented by formulae (P12), (p13), (p16), and (p17) include stereoisomers. Specifically, the isoflavanone compounds of formulae (p12) and (p16) include stereoisomers in which the C2 carbon is an asymmetric carbon atom, and the isoflavanone compounds of formulae (p13) and (p17) include stereoisomers in which the C3 atom is an asymmetric carbon atom.

[0072] The phenoxy resin (C) obtained by reacting the above-mentioned bifunctional epoxy compound (c1), polyfunctional epoxy compound (c2), and polyfunctional phenol compound (c3) contains structural units derived from the bifunctional epoxy compound (c1), polyfunctional epoxy compound (c2), and polyfunctional phenol compound (c3). The composition of the phenoxy resin (C) can be controlled by adjusting the amounts of the raw materials (c1), (c2), and (c3) used in its synthesis. In a preferred embodiment, the epoxy equivalent ratio (c1:c2) of the structural units derived from the bifunctional epoxy compound (c1) to the structural units derived from the polyfunctional epoxy compound (c2) in the phenoxy resin (C) is, for example, 99:1 to 90:10, preferably 98:2 to 91:9, and more preferably 97:3 to 92:8. If the epoxy equivalent ratio of the structural units derived from the polyfunctional phenol compound (c3) exceeds the above range, the solvent solubility of the resulting phenoxy resin (C) may decrease. By having the epoxy equivalent ratio (c1:c2) within the above range, the phenoxy resin (C) of the present embodiment has excellent solvent solubility, and therefore a thermosetting resin composition having excellent handleability in the form of a varnish can be suitably produced.

[0073] The phenoxy resin (C) used in this embodiment may contain structural units derived from other components (c4) in addition to the bifunctional epoxy compound (c1), polyfunctional epoxy compound (c2), and polyfunctional phenol compound (c3) described above, as long as the properties of the phenoxy resin are not affected. Examples of component (c4) include naphthalene-type epoxy compounds, glycidyl ester-type epoxy compounds, glycidyl amine-type epoxy compounds, alicyclic epoxy compounds, Bis-A-type epoxy compounds, Bis-E-type epoxy compounds, Bis-F-type epoxy compounds, Bis-S-type epoxy compounds, and bisphenol compounds, which are precursors of these. When the phenoxy resin (C) contains structural units derived from component (c4), the content of these structural units is, for example, 10 mol% or less, preferably 5 mol% or less, based on the total structural units constituting the phenoxy resin (C).

[0074] An example of the naphthalene type epoxy compound is a bifunctional epoxy compound represented by formula (EP1).

[0075] [ka]

[0076] In formula (EP1), R 14 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0077] In one embodiment, the phenoxy resin (C) is a difunctional epoxy compound (c1) of 4,4′-diglycidylbiphenyl and / or 4,4′-diglycidyl-3,3′,5,5′-tetramethylbiphenyl, and a pentafunctional trisphenolmethane epoxy compound represented by formula (m1) (n1=1, R 11 =H) with difunctional 2,7-dihydroxynaphthalene and / or 2,6-dihydroxynaphthalene as a polyfunctional phenol compound (c3).

[0078] In one embodiment, the phenoxy resin (C) is a mixture of 4,4′-diglycidylbiphenyl and / or 4,4′-diglycidyl-3,3′,5,5′-tetramethylbiphenyl as a difunctional epoxy compound (c1) and a tetrafunctional naphthalene-type epoxy compound (R 12 =H, R 13 =H) and a bifunctional epoxy compound (R 14 =H) with difunctional 2,7-dihydroxynaphthalene and / or 2,6-dihydroxynaphthalene as the polyfunctional phenol compound (C).

[0079] In one embodiment, the phenoxy resin (C) is a resin obtained by reacting 4,4'-diglycidylbiphenyl and / or 4,4'-diglycidyl-3,3',5,5'-tetramethylbiphenyl as the difunctional epoxy compound (c1), a trifunctional triazine epoxy compound represented by formula (m4) as the polyfunctional epoxy compound (c2), and a difunctional 2,7-dihydroxynaphthalene and / or 2,6-dihydroxynaphthalene as the polyfunctional phenol compound (c3).

[0080] The weight-average molecular weight (Mw) of the phenoxy resin (C) used in this embodiment is, for example, 1,000 to 10,000, preferably 2,000 to 8,000, more preferably 3,000 to 7,000, and even more preferably 3,500 to 6,500. Mw is a value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve. By setting Mw within the above range, the thermal conductivity of the phenoxy resin (C) can be further improved.

[0081] In this embodiment, the weight-average molecular weight (Mw) of the phenoxy resin (C) can be measured by obtaining a molecular weight distribution curve using Gel Permeation Chromatography (GPC). The weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity index (PDI: Mw / Mn) of the phenoxy resin are calculated using polystyrene-equivalent values ​​obtained from a calibration curve of standard polystyrene (PS) obtained by GPC measurement.

[0082] The measurement conditions for GPC are, for example, as follows. Tosoh Corporation gel permeation chromatography device HLC-8320GPC Column: TSK-GEL GMH, G2000H, SuperHM-M manufactured by Tosoh Corporation Detector: RI detector for liquid chromatography Measurement temperature: 40℃ Solvent: THF Sample concentration: 2.0 mg / ml

[0083] The polydispersity (Mw / Mn) of the phenoxy resin (C) is, for example, 1.00 to 7.00, preferably 2.00 to 6.00, and more preferably 3.50 to 5.50. By setting the polydispersity within the above range, the thermal conductivity and fluidity of the phenoxy resin (C) can be further improved.

[0084] The phenoxy resin (C) may contain a low-molecular-weight phenoxy resin having a weight-average molecular weight (Mw) of 1,000 or less. When the phenoxy resin contains a low-molecular-weight phenoxy resin, the low-molecular-weight phenoxy resin accounts for, for example, 5% to 60% and preferably 5% to 50% of the total area of ​​components corresponding to a weight-average molecular weight Mw of 1,000 or less, relative to the total area (100%) of the entire molecular weight distribution obtained by GPC measurement. A phenoxy resin containing a low-molecular-weight phenoxy resin in an amount within the above range has improved fluidity and excellent handleability. Therefore, for example, processing stability is improved when the phenoxy resin is processed into a sheet or film form.

[0085] From the viewpoint of the effects of the present invention, the epoxy equivalent of the phenoxy resin (C) is, for example, 300 to 6,000 g / eq, preferably 350 to 5,000 g / eq, and more preferably 400 to 4,500 g / eq.

[0086] The phenoxy resin (C) can improve the thermal conductivity of its cured product by providing the specific configuration described above. The thermal conductivity of the cured product of the phenoxy resin (C) is, for example, 0.3 W / (m·K) or more, preferably 0.35 W / (m·K) or more, and more preferably 0.4 W / (m·K) or more. Because the phenoxy resin (C) itself has high thermal conductivity, the cured product of a thermosetting resin composition containing it can also have high thermal conductivity.

[0087] The phenoxy resin (C) has the above-mentioned specific structure, and thus its cured product has a high 1% weight loss temperature. The 1% weight loss temperature of the cured product of the phenoxy resin (C) is 300°C or higher, preferably 310°C or higher, more preferably 320°C or higher, and even more preferably 330°C or higher. The upper limit of the 1% weight loss temperature of the cured product of the phenoxy resin (C) is, for example, 400°C or lower.

[0088] (Production of phenoxy resin (C)) The phenoxy resin (C) used in this embodiment can be synthesized by reacting a bifunctional epoxy compound (c1) represented by formula (d-EP), a multifunctional epoxy compound (c2) having three or more epoxy groups, and a multifunctional phenol compound (c3) having at least two phenolic hydroxyl groups. The phenoxy resin (C) may be synthesized using the above-mentioned component (c4) in addition to the bifunctional epoxy compound (c1), multifunctional epoxy compound (c2), and multifunctional phenol compound (c3), as long as the effects of the present invention are not impaired.

[0089] [ka]

[0090] X in formula (d-EP) is as defined above. The difunctional epoxy compound (c1), the polyfunctional epoxy compound (c2) having three or more epoxy groups, and the polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups are the same as those described above for the phenoxy resin (C).

[0091] The above reaction can be carried out in the absence of a solvent or in the presence of a reaction solvent using a reaction catalyst.

[0092] Suitable reaction solvents include aprotic organic solvents such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, sulfolane, propylene glycol monomethyl ether, cyclohexanone, etc. Use of a reaction solvent can reduce the initial viscosity and improve the reactivity of the monomer.

[0093] As the reaction catalyst, a conventionally known polymerization catalyst can be used, and alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, and imidazole compounds are preferably used.

[0094] Specifically, a bifunctional epoxy compound (c1), a multifunctional epoxy compound (c2), a multifunctional phenol compound (c3), a reaction catalyst, and optionally a reaction solvent are added and melt-mixed under stirring. The heating temperature during melt-mixing is about 90 to 120°C, the mixing time is about 30 minutes to 2 hours, and the reaction pressure is normal pressure. After melt-mixing, the mixed solution is heated and a polymerization reaction is carried out at a predetermined reaction temperature under reduced pressure or normal pressure. The reaction temperature is about 140 to 180°C, the reaction time is about 2 to 20 hours, and the reaction pressure is about 1 to 760 Torr.

[0095] After the reaction is complete, the phenoxy resin (C) can be obtained as a resin dissolved in a suitable solvent by performing solvent substitution, etc. The phenoxy resin (C) obtained by the solvent reaction can also be obtained as a solvent-free solid resin by removing the solvent using an evaporator, etc.

[0096] In the above synthesis method, the degree of polymerization can be adjusted by appropriately selecting reaction conditions such as the amounts of starting materials used, reaction temperature, and reaction time, thereby obtaining a phenoxy resin having a desired weight average molecular weight.

[0097] (Thermal conductive filler (D)) The thermosetting resin composition of the present embodiment contains thermally conductive particles (D). The thermally conductive particles (D) may include, for example, highly thermally conductive inorganic particles having a thermal conductivity of 20 W / m K or more. Examples of highly thermally conductive inorganic particles include at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. These may be used alone or in combination of two or more.

[0098] The boron nitride may contain monodisperse particles, agglomerated particles, or a mixture thereof of scaly boron nitride. The scaly boron nitride may be granulated. The use of agglomerated particles of scaly boron nitride further enhances thermal conductivity. The agglomerated particles may be sintered or non-sintered.

[0099] The thermally conductive particles (D) (100% by mass) may contain 60% by mass or more, preferably 65% ​​by mass or more, and more preferably 70% by mass or more of the boron nitride. The upper limit is not particularly limited, but may be 100% by mass or less, preferably 95% by mass or less, and more preferably 90% by mass or less.

[0100] The content of the thermally conductive particles (D) is 100% by mass to 400% by mass, preferably 150% by mass to 350% by mass, and more preferably 200% by mass to 330% by mass, relative to the resin component (100% by mass) of the thermosetting resin composition. By making the content equal to or greater than the lower limit, thermal conductivity can be improved. By making the content equal to or less than the upper limit, deterioration of processability can be suppressed.

[0101] (curing accelerator) The thermosetting resin composition of the present embodiment may contain a curing accelerator as needed. The type and amount of the curing accelerator are not particularly limited, but an appropriate one can be selected from the viewpoints of reaction rate, reaction temperature, storage properties, and the like.

[0102] Examples of the curing accelerator include imidazoles, organic phosphorus compounds, tertiary amines, phenolic compounds, and organic acids. These may be used alone or in combination of two or more. Among these, it is preferable to use nitrogen atom-containing compounds such as imidazoles from the viewpoint of improving heat resistance.

[0103] Examples of the imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-diethylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazolium trimellitate.

[0104] Examples of the tertiary amines include triethylamine, tributylamine, 1,4-diazabicyclo[2.2.2]octane, and 1,8-diazabicyclo(5,4,0)undecene-7.

[0105] Examples of the phenolic compound include phenolic resin, bisphenol A, nonylphenol, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, and allylphenol. Examples of the organic acid include acetic acid, benzoic acid, salicylic acid, and p-toluenesulfonic acid.

[0106] The content of the curing accelerator may be 0.01% by mass to 10% by mass, 0.02% by mass to 5% by mass, or 0.05% by mass to 1.5% by mass relative to 100% by mass of the total thermosetting resin.

[0107] (Silane coupling agent) The thermosetting resin composition may contain a silane coupling agent, which can improve the compatibility of the thermally conductive filler in the thermosetting resin composition. The coupling agent may be added to the thermosetting resin composition, or may be used by treating the surface of the thermally conductive filler.

[0108] (Other additives) The thermosetting resin composition of the present embodiment may contain components other than the components described above, such as an antioxidant and a leveling agent.

[0109] [Method for producing thermosetting resin composition] The thermosetting resin composition of this embodiment can be prepared as a resin varnish (a varnish-like thermosetting resin composition) by dissolving, mixing, and stirring the above-mentioned components other than the thermally conductive filler in a solvent. This mixing can be performed using various mixers such as ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, and rotation-revolution dispersion.

[0110] The solvent is not particularly limited, but examples thereof include acetone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone.

[0111] A thermosetting resin composition in a B-stage state can be obtained by adding a thermally conductive filler to the resin varnish and kneading the mixture using a three-roll mill or the like. Adding the filler during kneading can disperse the inorganic filler more uniformly in the thermosetting resin, but this is not limitative. The thermally conductive filler may be added during kneading, or may be added when the resin varnish is mixed. From the viewpoint of dispersibility, it is preferable to add the nanoparticles dispersed in a specific solvent (nanoparticle dispersion) to the resin varnish. After kneading, the mixture may be cooled and solidified, and processed into granules, tablets, or sheets.

[0112] [Resin sheet] The resin sheet of the present embodiment is obtained by curing the thermosetting resin composition. Specifically, the resin sheet has a carrier substrate and a resin layer formed on the carrier substrate and made of the thermosetting resin composition of the present embodiment.

[0113] The resin sheet can be obtained by, for example, applying a varnish-like thermosetting resin composition to a carrier substrate, and then subjecting the resulting coating film (resin layer) to a solvent removal treatment. The solvent content in the resin sheet can be 10% by mass or less based on the total thermosetting resin composition. For example, the solvent removal treatment can be performed at 80°C to 200°C for 1 minute to 30 minutes.

[0114] The resin sheet (resin layer) of this embodiment is in a B-stage state, and the thermosetting resin composition that does not contain the thermally conductive particles (D) that serve as a binder preferably exhibits the following curing behavior. Specifically, a thermosetting resin composition not containing thermally conductive particles (D) is pre-dried at 115°C for 12 minutes to prepare a sheet in a B-stage state, and the curing torque of the sheet in the B-stage state is measured over time using a cone-plate rheometer at a measurement temperature of 180°C. The time T required from the start of measurement to reach the maximum torque is max When the torque reaches 50% of the maximum torque value after the start of measurement, T 50 Ratio to (T 50 / Tmax ) is preferably 0.1 to 1.0, more preferably 0.2 to 0.8, and even more preferably 0.25 to 0.75.

[0115] As the cone-plate rheometer, for example, the rheometer "MCR-301" manufactured by Anton Paar can be used. The measurement frequency can be 1 Hz and the oscillation angle can be 1%. The curing behavior (ratio (T 50 / T max )) in the above range, the cycle time during pressing can be maintained within an appropriate range, and the occurrence of molding defects such as voids can be suppressed, thereby improving the productivity of metal base substrates and the like, which will be described later.

[0116] In this embodiment, the carrier substrate may be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, release papers such as silicone sheets, and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and / or copper-based alloys, aluminum and / or aluminum-based alloys, iron and / or iron-based alloys, silver and / or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys.

[0117] The resin substrate of this embodiment has an insulating layer made of the cured product of the thermosetting resin composition, and can be used as a material for a printed circuit board on which electronic components such as LEDs and power modules are mounted.

[0118] [Electronic equipment] The cured resin sheet is used as a thermally conductive sheet interposed between a heat generating element and a heat dissipating element.

[0119] Examples of the heating element include a semiconductor element, an LED element, a substrate on which a semiconductor element or an LED element is mounted, a central processing unit (CPU), a power semiconductor, a lithium ion battery, and a fuel cell. Examples of the heat dissipator include a heat sink, a heat spreader, and a heat dissipation (cooling) fin. The heat dissipation insulator may be partially composed of the thermosetting resin composition of this embodiment, and specific examples include a heat dissipation sheet obtained by curing the thermosetting resin composition, and a laminate in which the heat dissipation sheet is laminated on a substrate (for example, metal base substrate 100 in FIG. 1). The substrate is not particularly limited as long as it is a heat dissipation metal substrate, but examples include a copper substrate, a copper alloy substrate, an aluminum substrate, and an aluminum alloy substrate, with a copper substrate or an aluminum substrate being preferred, and a copper substrate being more preferred. Using a copper substrate or an aluminum substrate can improve the heat dissipation properties of the heat dissipation insulator. The heat dissipating and insulating member is partially composed of the thermosetting resin composition of this embodiment, and its thermal conductivity is preferably 12 W / m·K or more, and more preferably 15 W / m·K or more. The heat dissipating insulator and the heat sink may be formed on one or both sides of the heating element. Various substrates or layers may be provided between the heating element and the heat dissipating insulator, or between the heat dissipating insulator and the heat sink, as long as they do not affect heat dissipation.

[0120] In this embodiment, the heat generating element, the heat dissipating insulation member, and the heat dissipating element can be appropriately combined from those described above to obtain a laminated structure. The laminated structure can be used in various applications requiring heat dissipation and insulation, such as semiconductor devices, smartphones, LED bulbs and lights, power modules, lithium-ion batteries, fuel cells, wireless base stations, and uninterruptible power supplies. The components contained in the thermosetting resin composition of this embodiment will be described below.

[0121] [Metal base board] A metal base substrate (heat dissipating resin member) 100 of this embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a metal base substrate 100. As shown in FIG.

[0122] 1, the metal base substrate 100 can include a metal substrate 101, an insulating layer 102 provided on the metal substrate 101, and a metal layer 103 provided on the insulating layer 102. The insulating layer 102 can be made of one material selected from the group consisting of a resin layer made of the above-mentioned thermosetting resin composition, a cured product of the thermosetting resin composition, and a laminate. Each of these resin layers and laminates may be made of a thermosetting resin composition (resin sheet) in a B-stage state before circuit processing of the metal layer 103, and may be a cured product obtained by curing the resin composition after circuit processing.

[0123] The metal layer 103 is provided on the insulating layer 102 and is subjected to circuit processing. Examples of metals constituting the metal layer 103 include one or more selected from copper, copper alloys, aluminum, aluminum alloys, nickel, iron, tin, and the like. Among these, the metal layer 103 is preferably a copper layer or an aluminum layer, and particularly preferably a copper layer. The use of copper or aluminum can improve the circuit processability of the metal layer 103. The metal layer 103 may be a metal foil available in a plate form or a metal foil available in a roll form.

[0124] The lower limit of the thickness of the metal layer 103 is, for example, 0.01 mm or more, and preferably 0.035 mm or more, so that the metal layer 103 can be used in applications requiring a high current. The upper limit of the thickness of the metal layer 103 is, for example, 10.0 mm or less, and preferably 5 mm or less. If the thickness is equal to or less than this value, circuit processability can be improved, and the entire substrate can be made thinner.

[0125] The metal substrate 101 has a role of dissipating heat accumulated in the metal base substrate 100. The metal substrate 101 is not particularly limited as long as it is a heat-dissipating metal substrate, but may be, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate, with a copper substrate or an aluminum substrate being preferred, and a copper substrate being more preferred. By using a copper substrate or an aluminum substrate, the heat dissipation properties of the metal substrate 101 can be improved. The thickness of the metal substrate 101 can be set appropriately as long as it does not impair the object of the present invention.

[0126] The upper limit of the thickness of the metal substrate 101 is, for example, 20.0 mm or less, and preferably 5.0 mm or less. When the thickness is less than this value, the workability of the metal base substrate 100 can be improved in the outline processing, cutting processing, and the like.

[0127] The lower limit of the thickness of the metal substrate 101 is, for example, 0.01 mm or more, and preferably 0.6 mm or more. By using a metal substrate 101 with a thickness equal to or greater than this value, the heat dissipation properties of the metal base substrate 100 as a whole can be improved.

[0128] In this embodiment, the metal base substrate 100 can be used for various substrate applications, but because it has excellent thermal conductivity and heat resistance, it can be used as a printed circuit board that uses an LED or power module.

[0129] The metal base substrate 100 may have a metal layer 103 that has been circuitized by etching or the like into a pattern. In this metal base substrate 100, a solder resist (not shown) may be formed on the outermost layer, and connection electrodes may be exposed so that electronic components can be mounted thereon by exposure and development.

[0130] [Semiconductor Devices] The metal base substrate (heat dissipation and insulation member) 100 of the embodiment can be used in various applications that require heat dissipation and insulation, for example, in electronic devices such as semiconductor devices. FIG. 2 is a schematic cross-sectional view showing an example of a semiconductor device using the metal base substrate 100. As shown in FIG. A semiconductor element 201 is mounted on a metal layer 103 of a metal base substrate 100 via an adhesive layer 202 (die attach material). The semiconductor element 201 is connected to a connection electrode portion formed on the metal base substrate 100 via a bonding wire 203, and is mounted on the metal base substrate 100. The semiconductor element 201 is encapsulated on the metal base substrate 100 by an encapsulation resin layer 205 .

[0131] A heat sink 207 is provided on the metal substrate 101 side of the metal base substrate 100 via a thermally conductive layer 206 (thermal interface material (TIM)). The heat sink 207 is made of a material with excellent thermal conductivity, such as aluminum, iron, or copper.

[0132] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. [Example]

[0133] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0134] <Example 1 and Comparative Example 1 (Production of Thermosetting Resin Composition (Varnish))> A varnish-like thermosetting resin composition was obtained by stirring each component and solvent according to the blending ratios shown in Table 1. In Table 1, the content of thermally conductive particles is expressed as volume % relative to the resin component of the thermosetting resin composition not including the thermally conductive filler. Details of each component in Table 1 are as follows: The amount of each component in Table 1 is expressed in parts by mass.

[0135] (epoxy resin) Epoxy resin 1: Epoxy resin with the following structure (DIC Corporation, HP-4032D, liquid at room temperature) [ka]

[0136] Epoxy resin 2: Dicyclopentadiene epoxy resin (DIC, EPICLON HP-7200L, solid at room temperature)

[0137] (cyanate resin) Cyanate resin 1: Primaset "PT-30S" manufactured by Lonza

[0138] (phenolic resin) Phenolic resin 1: Allyl group-containing phenolic novolac resin (manufactured by Meiwa Kasei Co., Ltd., product name "MEH-8000H")

[0139] (phenoxy resin) Phenoxy resin 1: Phenoxy resin obtained by the following procedure. 64 parts by weight of epoxy compound (YL6121:TEPIC-S = 95:5 (epoxy equivalent ratio)), 30 parts by weight of 2,7-dihydroxynaphthalene, 0.05 parts by weight of triphenylphosphine (TPP), and 7 parts by weight of solvent (cyclohexanone) were added to a reactor and melt-mixed at 100 to 110°C for 1 hour. The mixture was then heated to 150°C and reacted at that temperature while removing the solvent under reduced pressure. Once the target molecular weight was confirmed by GPC, the reaction was terminated to obtain a phenoxy resin. The reaction was carried out for 6 hours. After the reaction, 100 parts by weight of dimethylformamide was added to the resin to dissolve the resin, and the resin was cooled to room temperature. After cooling, the resin was purified by reprecipitation using methanol to obtain 100 parts by weight of phenoxy resin (weight average molecular weight Mw measured by GPC was 5300, and the polydispersity (weight average molecular weight Mw) / (number average molecular weight Mn) was 4.28).

[0140] Phenoxy resin 2: Phenoxy resin obtained by the following procedure. 64 parts by weight of epoxy compound (YL-6121:YL-6677 = 97.5:2.5 (epoxy equivalent ratio)), 30 parts by weight of 2,7-dihydroxynaphthalene, 0.05 parts by weight of triphenylphosphine (TPP), and 7 parts by weight of solvent (cyclohexanone) were added to a reactor and melt-mixed at 100-110°C for 1 hour. The mixture was then heated to 150°C and reacted at that temperature while removing the solvent under reduced pressure. Once the target molecular weight was confirmed by GPC, the reaction was terminated to obtain a phenoxy resin. The reaction was carried out for 15 hours. After the reaction, 100 parts by weight of dimethylformamide was added to the resin to dissolve it, and the resin was cooled to room temperature. After cooling, the mixture was purified by reprecipitation using methanol to obtain 100 parts by weight of a phenoxy resin (weight average molecular weight Mw measured by GPC was 5100, and the dispersity (weight average molecular weight Mw) / (number average molecular weight Mn) was 4.19).

[0141] Phenoxy resin 3: A phenoxy resin obtained by the following procedure. 64 parts by weight of an epoxy compound (YL-6121), 30 parts by weight of 2,7-dihydroxynaphthalene, 0.05 parts by weight of triphenylphosphine (TPP), and 7 parts by weight of a solvent (cyclohexanone) were added to a reactor and melt-mixed at 100-110°C for 1 hour. The mixture was then heated to 150°C and reacted at that temperature while removing the solvent under reduced pressure. Once the target molecular weight was confirmed by GPC, the reaction was terminated to obtain a phenoxy resin. The reaction was carried out for 15 hours. After the reaction, 100 parts by weight of dimethylformamide was added to the resin to dissolve the resin, and the resin was cooled to room temperature. After cooling, the resin was purified by reprecipitation using methanol to obtain 100 parts by weight of a phenoxy resin (GPC weight-average molecular weight Mw was 5600, and the dispersity (weight-average molecular weight Mw) / (number-average molecular weight Mn) was 4.34).

[0142] The raw material compounds used in the synthesis of the above phenoxy resin 1 and phenoxy resin 2 are as follows. (Difunctional epoxy compound (c1)) YL-6121: A mixture of 50% by mass of a tetramethylbiphenyl-type epoxy compound represented by the following formula (3) and 50% by mass of a biphenyl-type epoxy compound represented by the following formula (4). Epoxy equivalent: 171. Manufactured by Mitsubishi Chemical Corporation. [ka] [ka]

[0143] (Multifunctional epoxy compound (c2)) TEPIC-S (triglycidyl isocyanurate): A trifunctional triazine-type epoxy compound represented by formula (14). Epoxy equivalent: 110. Manufactured by Nissan Chemical Industries, Ltd. [ka]

[0144] YL-6677: A mixture of 25% by mass of a biphenyl-type epoxy compound represented by formula (4) and 75% by mass of a trisphenolmethane-type epoxy resin (n1 = 0 to 4) represented by formula (5). Epoxy equivalent: 163. Manufactured by Mitsubishi Chemical Corporation.

[0145] [ka] [ka] 1

[0146] (curing accelerator) Curing accelerator 1: Novolac-type phenol compound (PR-51470, manufactured by Sumitomo Bakelite Co., Ltd.)

[0147] (thermally conductive particles) Thermally conductive particles 1: Agglomerated boron nitride (HP40, manufactured by Mizushima Ferroalloy Co., Ltd.)

[0148] <Measurement of physical properties of resin molded products of thermosetting resin compositions> The cured product (resin molded product) of the thermosetting resin composition was measured for the following physical properties. The results are shown in Table 1.

[0149] (thermal conductivity) -Making resin molded products The obtained thermosetting resin composition containing the thermally conductive filler was sandwiched between 0.018 mm copper foils and compression molded at 10 MPa, 180°C, and 90 minutes to obtain a resin molded body (thermal conductivity measurement sample 1). A sample with a diameter of 10 mm for thermal diffusivity measurement was cut out from the obtained molded body and used for thermal diffusivity measurement.

[0150] Density (specific gravity) of resin moldings The density (specific gravity) measurement was carried out in accordance with JIS K 6911 (general testing method for thermosetting plastics). Test pieces were cut out from the above resin molded body to a size of 2 cm length x 2 cm width. The density (specific gravity) (ρ) was measured in g / cm. 3 The results are shown in Table 1.

[0151] Specific heat of resin moldings The specific heat (Cp) of the resin molded article obtained above was measured by the DSC method.

[0152] Measurement of thermal conductivity of resin molded products A 10 mm diameter specimen was cut from the resulting resin molded article to be used for thickness direction measurement. The thermal diffusion coefficient (α) of the plate-shaped specimen in the thickness direction was measured by a transient method using a ULVAC Xe flash analyzer TD-1RTV. The measurement was performed under atmospheric conditions at 25°C. The thermal conductivity of the resin molded article was calculated from the measured values ​​of the thermal diffusion coefficient (α), specific heat (Cp), and density (ρ) according to the following formula. The results are shown in Table 1. Thermal conductivity [W / m K]=α[m 2 / s]×Cp[J / kg·K]×ρ[g / cm 3 ] In Table 1, the thermal conductivity of the resin molded body is shown as "thermal conductivity."

[0153] (moisture absorption rate) The copper foil was removed from the resulting resin molded product by etching, and the product was left to stand at 30°C / 90% RH for 48 hours, and the moisture absorption rate (%) was calculated from the change in weight before and after the treatment.

[0154] (solder heat resistance) The obtained resin molded body was cut into 50 mm x 50 mm pieces using a grinder saw, and then etched to create samples with only half of the copper foil remaining, which were evaluated in accordance with JIS C 6481. The evaluation was carried out by immersing the samples in a solder bath at 300°C for 5 minutes and then examining the appearance for any abnormalities. The evaluation criteria were as follows: <Evaluation criteria> ○: No abnormalities ×: Abnormal (bulging areas throughout)

[0155] (Moisture absorption and solder heat resistance) The resulting resin molded body was cut into 50 mm x 50 mm pieces using a grinder saw, and then half of the surface was etched according to JIS C 6481 to prepare specimens. After leaving the specimens in an environment of 40°C and 90% humidity for two days, they were placed in a solder bath at 297°C with the copper foil side facing downwards and inspected for any abnormalities in appearance after one minute. The evaluation criteria were as follows. The results are shown in Table 1. <Evaluation criteria> ○: No abnormalities ×: Swelling (there are bulges all over the body)

[0156] [Table 1]

Claims

1. (A) an epoxy resin; (B) a thermosetting resin (excluding the epoxy resin (A)); (C) a phenoxy resin; (D) a thermally conductive filler, The phenoxy resin (C) is a bifunctional epoxy compound (c1) having two epoxy groups; a polyfunctional epoxy compound (c2) having three or more epoxy groups; a polyfunctional phenol compound (c3) having at least two phenolic hydroxyl groups, The bifunctional epoxy compound (c1) includes a compound represented by formula (d-EP): 【Chemistry 1】 X in the formula (d-EP) is a divalent organic group having a mesogenic skeleton represented by formula (2), 【Chemistry 2】 In formula (2), R １ ~R ８ are independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, * represents the linking position, The polyfunctional phenol compound (c3) includes at least one selected from the compounds represented by formulas (p1) to (p17), 【Transformation 3】 【Chemistry 4】 【Transformation 5】 【Transformation 6】 【Transformation 7】 【Transformation 8】 In formulas (p1) to (p17), R independently represents a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 6 carbon atoms. Thermosetting resin composition.

2. 2. The thermosetting resin composition according to claim 1, wherein the polyfunctional epoxy compound (c2) comprises at least one selected from a trisphenolmethane type epoxy resin, a naphthalene type epoxy compound, and a triazine type epoxy compound.

3. In the group represented by formula (2), R １ , R ４ , R ５ , and R ８ is an alkyl group having 1 to 6 carbon atoms, and R ２ , R ３ , R ６ , and R ７ The thermosetting resin composition according to claim 1 or 2, wherein is a hydrogen atom.

4. In the group represented by formula (2), R １ , R ４ , R ５ , and R ８ is a methyl group, and R ２ , R ３ , R ６ , and R ７ The thermosetting resin composition according to claim 1 or 2, wherein is a hydrogen atom.

5. In the group represented by formula (2), R １ ~R ８ The thermosetting resin composition according to claim 1 or 2, wherein all of the following are hydrogen atoms.

6. At least one of X in the formula (d-EP) is R １ , R ４ , R ５ , and R ８ is a methyl group, and R ２ , R ３ , R ６ , and R ７ is a divalent group represented by the formula (2) in which At least one of X in the formula (d-EP) is R １ ~R ８ The thermosetting resin composition according to claim 1 , wherein all of the groups represented by the formula (2) are hydrogen atoms.

7. The thermosetting resin composition according to claim 1 , wherein the polyfunctional epoxy compound (c2) has an epoxy equivalent of 50 g / eq or more and 300 g / eq or less.

8. The thermosetting resin composition according to any one of claims 1 to 7, wherein the polyfunctional epoxy compound (c2) comprises at least one epoxy compound selected from the group consisting of formulas (m1) to (m4): 【Chemistry 9】 【Chemistry 10】 In formulas (m1) to (m3), R １１ ~R １３ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n1 in formula (m1) is an integer of 0 to 4.

9. The thermosetting resin composition according to any one of claims 1 to 8, wherein the bifunctional epoxy compound (c1) further comprises an epoxy compound represented by formula (EP1): 【Chemistry 11】 In formula (EP1), R １４ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

10. 10. The thermosetting resin composition according to claim 1, wherein the phenoxy resin (C) comprises a structural unit derived from the difunctional epoxy compound (c1), a structural unit derived from the polyfunctional epoxy compound (c2), and a structural unit derived from the polyfunctional phenol compound (c3).

11. 11. The thermosetting resin composition according to claim 10, wherein the epoxy equivalent ratio (c1:c2) of the structural unit derived from the difunctional epoxy compound (c1) to the structural unit derived from the polyfunctional epoxy compound (c2) in the phenoxy resin (C) is 99:1 to 90:

10.

12. The thermosetting resin composition according to claim 1 , wherein the phenoxy resin (C) has a weight average molecular weight of 1,000 or more and 10,000 or less.

13. The thermosetting resin composition according to claim 1 , wherein the cured product of the phenoxy resin (C) has a thermal conductivity of 0.3 W / (m·K) or more.

14. The thermosetting resin composition according to claim 1 , further comprising an organic solvent (E).

15. The thermosetting resin composition according to claim 1 , wherein the epoxy resin (A) comprises an epoxy resin that is liquid at room temperature.

16. The thermosetting resin composition according to claim 15, wherein the epoxy resin (A) further comprises an epoxy resin that is solid at room temperature.

17. 17. The thermosetting resin composition according to claim 1, wherein a content of the thermally conductive filler (D) is 60 mass% or more and 98 mass% or less with respect to a total solid content of the thermosetting resin composition.

18. 18. The thermosetting resin composition according to claim 1, wherein the thermally conductive filler (D) comprises at least one selected from silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide.

19. The thermosetting resin composition according to claim 1 , wherein the thermally conductive filler (D) comprises boron nitride.

20. 20. The thermosetting resin composition according to claim 18 or 19, wherein the boron nitride is in the form of monodisperse particles, granular particles, agglomerated particles, or a mixture thereof, of scaly boron nitride.

21. 21. The thermosetting resin composition according to claim 1, wherein the thermosetting resin (B) comprises at least one selected from the group consisting of a cyanate resin, a maleimide resin, a phenolic resin, and a benzoxazine resin.

22. The thermosetting resin composition according to claim 1 , wherein the thermosetting resin (B) comprises a cyanate resin.

23. The thermosetting resin composition according to claim 1 , further comprising a curing accelerator.

24. A resin sheet comprising the thermosetting resin composition according to any one of claims 1 to 23.

25. The resin sheet according to claim 24, which is in a B-stage state.

26. A heat-generating member; A heat dissipation member; a heat-conductive sheet provided between the heat-generating component and the heat-dissipating component, 26. An electronic device, wherein the thermally conductive sheet is made of a cured resin sheet according to claim 24 or 25.

27. 27. The electronic device according to claim 26, wherein the thermal conductivity of the thermally conductive sheet is 12 W / m·K or more.

28. A metal substrate; a thermally conductive sheet; A metal base substrate comprising, in this order, 26. A metal base substrate, wherein the insulating layer is made of a cured product of the resin sheet according to claim 24 or 25.

29. 29. The metal base substrate according to claim 28, wherein the thermal conductivity of the thermally conductive sheet is 12 W / m·K or more.

30. 30. An electronic device comprising the metal base substrate of claim 29.

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