Thermosetting resin composition, resin sheet and metal base substrate

Abstract

To provide a thermosetting resin composition suitable for forming a heat radiation member in a power module.SOLUTION: Provided is a thermosetting resin composition containing an epoxy resin and thermally conductive particles. A cured product obtained by heating the thermosetting resin composition at 200°C for 90 minutes has a thermal conductivity λ200 at 200°C of at least 12 W / (m K). Also, the cured product has a volume resistivity R200 at 200°C of preferably at least 1.0×1010 Ω m. In addition, provided is a resin sheet using the thermosetting resin composition. Furthermore, provided is a metal base substrate using the thermosetting resin composition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermosetting resin composition, a resin sheet, and a metal base substrate. More specifically, the present invention relates to a thermosetting resin composition, and a resin sheet and a metal base substrate comprising the thermosetting resin composition or a cured product thereof. [Background technology]

[0002] There are cases where heat dissipation properties are required for resin materials constituting electric / electronic devices, etc. In order to meet this requirement, the use of thermosetting resin compositions to form heat dissipation members has been considered.

[0003] As an example, Patent Document 1 describes a thermosetting resin composition in which a thermally conductive filler is dispersed in a thermosetting resin matrix. In this thermosetting resin composition, the filler is a secondary aggregate formed by agglomeration of primary particles that are crystals of boron nitride. The main constituent materials of the resin matrix are an epoxy resin and a phenolic hardener, and the epoxy resin contains a naphthalene-type epoxy resin and a bisphenol A-type epoxy resin. The glass transition temperature of the cured product of this thermosetting resin composition is 170°C or higher, and the viscosity of this thermosetting resin composition at 100°C before curing is 20 Pa·s or lower.

[0004] As another example, Patent Document 2 describes a method for producing a multilayer resin sheet by forming a resin composition containing an epoxy resin having a mesogenic skeleton, a curing agent, and an inorganic filler into a sheet shape to obtain a resin layer, and an adhesive layer forming step of providing an insulating adhesive layer on at least one surface of the resin layer, for the purpose of achieving high thermal conductivity, etc. It also describes applying light or heat to the multilayer resin sheet to cure the resin layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6000749 [Patent Document 2] JP 2014-139021 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, attempts to form heat dissipation members from thermosetting resin compositions containing epoxy resins and the like are known. However, according to the findings of the present inventors, there is still room for improvement in conventional heat dissipation members. For example, when a heat dissipation member in a power module is formed using a conventional thermosetting resin composition for forming a heat dissipation member, there is still room for improvement in terms of heat dissipation and insulation. This is particularly problematic in power modules that require high reliability.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermosetting resin composition suitable for forming a heat dissipation member in a power module. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have completed the invention provided below and have solved the above-mentioned problems.

[0009] According to the present invention, A thermosetting resin composition comprising an epoxy resin and thermally conductive particles, The thermal conductivity λ of the cured product obtained by heating the thermosetting resin composition at 200°C for 90 minutes at 200°C 200 The thermal resistance of the thermosetting resin composition is 12 W / (m·K) or more. is provided.

[0010] Further, according to the present invention, A carrier substrate; a resin layer formed on the carrier substrate and made of the thermosetting resin composition; is provided.

[0011] Further, according to the present invention, A metal substrate; an insulating layer provided on the metal substrate; a metal layer provided on the insulating layer, A metal base substrate, wherein the insulating layer is a resin layer made of the above-mentioned thermosetting resin composition or a cured product of the above-mentioned thermosetting resin composition. is provided. Effect of the Invention

[0012] According to the present invention, there is provided a thermosetting resin composition which is suitable for forming a heat dissipation member in a power module. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a configuration of a metal base substrate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, similar components are given similar symbols and descriptions thereof will be omitted as appropriate. In order to avoid complexity, when there are multiple identical components in the same drawing, only one of them may be labeled with a reference symbol, and not all of them. The drawings are for illustrative purposes only. The shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0015] In this specification, unless otherwise specified, the expression "X to Y" in the explanation of a numerical range means from X to Y. For example, "1 to 5% by mass" means "from 1% by mass to 5% by mass".

[0016] In the description of groups (atomic groups) in this specification, when a description is made without specifying whether the group is substituted or unsubstituted, the description includes both groups having no substituents and groups having a substituent. For example, an "alkyl group" includes not only an alkyl group having no substituents (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, the term "organic group" means an atomic group obtained by removing one or more hydrogen atoms from an organic compound, unless otherwise specified. For example, a "monovalent organic group" refers to an atomic group obtained by removing one hydrogen atom from any organic compound.

[0017] <Thermosetting resin composition> The thermosetting resin composition of the present embodiment contains an epoxy resin and thermally conductive particles. The thermal conductivity λ of the cured product obtained by heating the thermosetting resin composition of the present embodiment at 200°C for 90 minutes is 200 is 12 W / (m K) or more. In addition, preferably, the volume resistivity R at 200° C. of the cured product obtained under the above heating conditions is 200 is 1.0 × 10 10 It is greater than or equal to Ω·m.

[0018] The present inventors have investigated from various perspectives the reason why there is still room for improvement in the heat dissipation and insulation properties of conventional heat dissipation members, particularly in the field of power modules. As a result of the investigation, it was thought that the power module for a generator may be installed close to the turbine, which may have something to do with heat dissipation and insulation. Specifically, when the power module is installed close to the turbine, the temperature around the power module becomes relatively high, which may cause the heat dissipation from the heat dissipation member to be insufficient and may cause the insulation to deteriorate. Further investigations based on this consideration led the inventors to discover that the thermal conductivity of the heat dissipation member, not in the usual room temperature environment for evaluation, but in a high temperature environment, is closely related to the performance of the power module for a generator.

[0019] Based on the above findings, the present inventors have determined that the thermal conductivity λ of a cured product obtained by heating a thermosetting resin composition at 200° C. for 90 minutes is 200° C. 200 was set as one of the indices for designing thermosetting resin compositions. And, newly, λ 200 By preparing a thermosetting resin composition with a thermal conductivity of 12 W / (m K) or higher (and using that thermosetting resin composition to form the resin components in a power module), they succeeded in improving the heat dissipation and insulation properties of a power module placed in a relatively high-temperature environment. λ 200 is preferably 12 to 25 W / (m·K), and more preferably 13 to 23 W / (m·K).

[0020] The present inventors also measured the volume resistivity R at 200° C. of a cured product obtained by heating the thermosetting resin composition at 200° C. for 90 minutes. 200 In the present embodiment, preferably, R 200 is 1.0×10 10 This makes it easier to reduce leakage current during high-temperature operation of the power module and to suppress leakage current and short circuits. 200 is preferably 1.0 x 10 10 ~1.0×10 14 Ω·m, more preferably 3.0×10 10 ~7.0×10 13 Ω·m, and more preferably 5.0×10 10 ~5.0×10 13 Ω m. By the way, when metal particles are used as thermally conductive particles, λ 200 can be easily designed to be 12 W / (m K) or more. However, in that case, R 200 to 1.0×10 10 It is not easy to design it to have a resistance of more than Ω·m. 200 is 1.0×10 10 A resistivity of Ω·m or more can be said to numerically express that the preferred application of the thermosetting resin composition of this embodiment is as an "insulating material" and that the composition does not contain metal particles that are undesirable from the viewpoint of insulation properties.

[0021] In this embodiment, by using appropriate materials such as epoxy resin and by appropriately adjusting the amount of each material, λ 200 Or R 200 It is possible to produce a thermosetting resin composition having the above-mentioned values. Specific materials and the amounts used will be explained below as appropriate.

[0022] The components, properties, physical properties, etc. of the thermosetting resin composition of the present embodiment will be described in more detail below.

[0023] (Epoxy resin) The thermosetting resin composition of the present embodiment contains an epoxy resin. The thermosetting resin composition of the present embodiment is a composition that is cured by heat due to the inclusion of an epoxy resin or the like.

[0024] The epoxy resin may be any known one without any particular limitation, such as 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.

[0025] The epoxy resin preferably contains a mesogenic skeleton, which can further increase the thermal conductivity (heat dissipation) during curing. It is believed that when an epoxy resin containing a mesogenic skeleton is cured, the mesogenic skeleton forms a higher-order structure (liquid crystal phase or crystalline phase), and that the thermal conductivity (heat dissipation) is further increased by the transfer of heat through the higher-order structure. The presence of a higher-order structure in a cured product can be examined by observation with a polarizing microscope.

[0026] The mesogenic skeleton may be any skeleton that facilitates 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, and a phenanthrene skeleton.

[0027] The epoxy resin particularly preferably contains a condensed polycyclic aromatic hydrocarbon skeleton, and particularly preferably contains a naphthalene skeleton. For example, in the case of a biphenyl skeleton (-C6H4-C6H4-), the central carbon-carbon single bond in the structure on the left may "rotate" due to thermal motion at high temperatures, which may result in a decrease in liquid crystallinity. Similarly, in the case of a phenylbenzoate skeleton (-C6H4-COO-C6H4-), the ester bond may rotate at high temperatures. However, in the case of a condensed polycyclic aromatic hydrocarbon skeleton such as a naphthalene skeleton, in principle, such rotation will not cause a decrease in liquid crystallinity. In other words, when an epoxy resin contains a condensed polycyclic aromatic hydrocarbon skeleton, the λ 200 It is easy to design the insulation resistance to be 12 W / (m K) or more, which makes it easier to further improve heat dissipation in high-temperature environments. In addition, by employing a naphthalene skeleton as the polycyclic aromatic hydrocarbon skeleton, the epoxy resin can be prevented from becoming too rigid while obtaining the above-mentioned advantages. This is because the naphthalene skeleton is relatively small as a mesogen skeleton. The epoxy resin not becoming too rigid is preferable in terms of preventing cracks and the like caused by the stress during curing of the thermosetting resin composition of this embodiment being easily relaxed.

[0028] The epoxy resin preferably contains a di- or higher-functional epoxy resin. In other words, it is preferable that one molecule of the epoxy resin contains two or more epoxy groups. The number of functional groups of the epoxy resin is preferably 2 to 6, and more preferably 2 to 4.

[0029] Preferred epoxy resins are, for example, one or more of the following:

[0030] [ka]

[0031] The epoxy equivalent of the epoxy resin 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 having an appropriate epoxy equivalent, it is possible to control the curing property and optimize the physical properties of the cured product.

[0032] In one embodiment, the epoxy resin preferably includes a liquid epoxy resin that is liquid at room temperature (23° C.). Specifically, it is preferable that a part or the whole of the epoxy resin is liquid at 23° C. The use of a liquid epoxy resin is preferable in terms of the ease of forming a cured product in a desired shape.

[0033] The thermosetting resin composition of the present embodiment may contain only one type of epoxy resin, or may contain two or more types of epoxy resins. The lower limit of the epoxy resin content is, for example, 5% by mass or more, preferably 7% by mass or more, and more preferably 10% by mass or more, based on the total non-volatile components other than the thermally conductive particles. This ensures sufficient curability. The upper limit of the epoxy resin content is, for example, 40 mass% or less, preferably 35 mass% or less, and more preferably 30 mass% or less, based on the total non-volatile components other than the thermally conductive particles. If the epoxy resin content is not too high, other components can be sufficiently contained, and λ 200 is 12W / (m K) or more and / or R 200 is 1.0×10 10 It is easy to design compositions that have a resistance of Ω·m or more, and it is also easy to further improve heat dissipation and insulation properties. Just to be clear, the term "non-volatile components" refers to components that do not volatilize and remain when a thermosetting resin composition is heated and cured. Usually, non-volatile components refer to components other than volatile solvents.

[0034] (Thermal Conductive Particles) The thermosetting resin composition of the present embodiment contains thermally conductive particles. The presence of the thermally conductive particles makes it easier to obtain sufficient heat dissipation properties.

[0035] The thermally conductive particles include at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. From the viewpoint of the balance between thermal conductivity and insulation, two or more different types of thermally conductive particles may be used in combination.

[0036] As the thermally conductive particles, boron nitride is particularly preferred because of its high thermal conductivity. The boron nitride may include, for example, monodisperse particles, agglomerated particles, or a mixture thereof, of boron nitride. The boron nitride may be granulated. By using agglomerated particles of boron nitride, the thermal conductivity can be further increased. The agglomerated particles may be sintered particles or non-sintered particles.

[0037] The amount of the thermally conductive particles is, for example, 100 to 400 parts by mass, preferably 150 to 350 parts by mass, and more preferably 200 to 300 parts by mass, when the total amount of non-volatile components other than the thermally conductive particles in the composition is 100 parts by mass. By using a sufficient amount of thermally conductive particles, the thermal conductivity can be sufficiently improved. By not using too much thermally conductive particles, the mechanical properties of the cured product can be improved.

[0038] (hardening agent) The thermosetting resin composition of the present embodiment preferably contains a curing agent. The curing agent is not particularly limited as long as it reacts with the epoxy groups in the epoxy resin to cure the composition.

[0039] As the inventors have found, in particular, by using as a curing agent at least a curing agent that does not generate a hydroxyl group by reaction with an epoxy group (hereinafter, this curing agent is also referred to as "curing agent (a)"), R 200 to 1.0×10 10 It is easy to design it to be Ω·m or higher, and the insulation properties can be improved. Although the details of the reason for this are unclear, it is believed that the decrease in the production of highly polar hydroxyl groups makes it difficult for current to flow.

[0040] The curing agent (a) may be a low molecular weight compound or a resin (polymer or oligomer).

[0041] Examples of the curing agent (a) include the following:

[0042] Polyarylate compounds, specifically compounds represented by the following general formula (a1):

[0043] [ka]

[0044] An active ester compound, for example, a compound represented by the following general formula (a2):

[0045] [ka]

[0046] Cyanate ester compounds, for example, compounds represented by the following general formula (a3):

[0047] [ka]

[0048] Isocyanate compounds, for example, compounds represented by the following general formula (a4):

[0049] [ka]

[0050] Imidazole compounds

[0051] In general formulae (a1), (a3), and (a4), R and R' are each independently a divalent linking group. R and R' are preferably groups containing conjugated double bonds. More specifically, R and R' are aromatic rings, aromatic condensed rings or groups of the general formula -A 1 -XA 2 In this general formula, A 1 and A 2 each independently represents a group selected from an aromatic group, a condensed aromatic group, an alicyclic group, and an alicyclic heterocyclic group, and X represents a single bond or a divalent linking group.

[0052] A 1 and A 2 Preferred examples of the alkyl group include a hydrocarbon group having 6 to 12 carbon atoms and containing a benzene ring, a hydrocarbon group having 10 to 20 carbon atoms and containing a naphthalene ring, a hydrocarbon group having 12 to 24 carbon atoms and containing a biphenyl structure, a hydrocarbon group having 12 to 36 carbon atoms and containing three or more benzene rings, a hydrocarbon group having 12 to 36 carbon atoms and containing a condensed aromatic group, and an alicyclic heterocyclic group having 4 to 36 carbon atoms.

[0053] A 1 and A 2 Specific examples of the alkyl group include phenylene, biphenylene, naphthylene, anthracenylene, cyclohexyl, pyridyl, pyrimidyl, thiophenylene, etc. These may be unsubstituted or may have a substituent such as an aliphatic hydrocarbon group, a halogen group, a cyano group, or a nitro group.

[0054] X is preferably, for example, a divalent substituent selected from the group consisting of a single bond, -C=C-, -C≡C-, -CO-O-, -CO-NH-, -CH=N-, -CH=NN=CH-, -N=N- and -N(O)=N-.

[0055] In general formula (a1), R1, R2, R3, and R4 each independently represent an aliphatic group having 1 to 4 carbon atoms, an aromatic group having 6 to 12 carbon atoms containing a benzene ring, or the like; Z is a hydrogen atom, a hydroxyl group or an alkoxy group; n is the number of repetitions, typically 1 to 100.

[0056] In general formula (a2), Ar and Ar' are each independently an aromatic group (which may be a heteroaromatic group), an alicyclic group, or the like. Specific examples of Ar and Ar' include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a cyclohexyl group, a pyridyl group, a pyrimidyl group, and a thienyl group. The aromatic and alicyclic groups of Ar and Ar' may be unsubstituted or may have a substituent, such as an aliphatic hydrocarbon group, a halogen group, a cyano group, or a nitro group.

[0057] When the curing agent (a) is used, only one type may be used, or two or more types may be used in combination. When the thermosetting resin composition of the present embodiment contains a curing agent (a), the equivalent ratio of the curing agent (a) to the epoxy resin in the thermosetting resin composition (the number of moles of reactive functional groups in the curing agent (a) / the number of moles of epoxy groups in the epoxy resin) is preferably 1.0 to 2.0, and more preferably 1.1 to 1.8.

[0058] The thermosetting resin composition of the present embodiment may contain a curing agent that does not fall under the category of curing agent (a). Examples of such a curing agent include phenol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, and mercaptan-based curing agents. When using these, they may be used alone or in combination of two or more.

[0059] When a curing agent is used, only one type may be used, or two or more types may be used in combination. When the thermosetting resin composition of the present embodiment contains a curing agent, the amount of the curing agent is preferably 20 to 70 mass %, more preferably 30 to 60 mass %, based on the total amount of non-volatile components other than the thermally conductive particles in the composition. By appropriately adjusting the amount of the curing agent, the heat dissipation property and the insulating property can be further improved. In addition, it may be possible to control the curing property and improve the mechanical properties of the cured product.

[0060] (Cure accelerator) The thermosetting resin composition of the present embodiment may contain a curing accelerator, which can accelerate the curing reaction. The type and amount of the curing accelerator are not particularly limited, and may be selected appropriately from the viewpoints of reaction speed, reaction temperature, storage properties, etc.

[0061] Examples of the curing accelerator include imidazoles, organic phosphorus compounds, organic metal salts, tertiary amines, phenol compounds, and organic acids. These may be used alone or in combination of two or more. Among these, from the viewpoint of heat resistance, at least one selected from the group consisting of organic phosphorus compounds, complexes of organic phosphorus compounds and organic boron compounds, and compounds having intramolecular polarization formed by adding a compound having a π bond to an organic phosphorus compound can be used. Examples of compounds having a π bond include maleic anhydride, quinone compounds, diazophenylmethane, and phenol resins. In addition, quaternary phosphonium salt compounds, quaternary ammonium salt compounds, fatty acid salt compounds, metal chelate compounds, and metal salt compounds may be used. Further, a latent curing accelerator such as a dihydrazide compound such as dicyandiimide or adipic acid dihydrazide, guanamic acid, melamine acid, an addition compound of an epoxy compound and an imidazole compound, an addition compound of an epoxy compound and a dialkylamine, an addition compound of an amine and a thiourea, or an addition compound of an amine and an isocyanate may be used.

[0062] Examples of 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.

[0063] Specific examples of the organic phosphorus compound include triphenylphosphine, tri-p-tolylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkyl / alkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine, dialkylarylphosphine, alkyldiarylphosphine, and 1,2-bis-(diphenylphosphino)ethane.

[0064] Specific examples of complexes of organic phosphine compounds and organic boron compounds include triphenylphosphine·triphenylborane, tetraphenylphosphonium·tetraphenylborate, tetraphenylphosphonium·tetra-p-tolylborate, tetrabutylphosphonium·tetraphenylborate, tetraphenylphosphonium·n-butyltriphenylborate, butyltriphenylphosphonium·tetraphenylborate, and methyltributylphosphonium·tetraphenylborate.

[0065] Examples of the organic metal salt include zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, cobalt bisacetylacetonate (II), and cobalt trisacetylacetonate (III). Examples of tertiary amines include triethylamine, tributylamine, 1,4-diazabicyclo[2.2.2]octane, and 1,8-diazabicyclo(5,4,0)undecene-7. Examples of the phenol compound include phenol, bisphenol A, nonylphenol, and 2,2-bis(3-methyl-4-hydroxyphenyl)propane. Examples of the organic acid include acetic acid, benzoic acid, salicylic acid, and p-toluenesulfonic acid.

[0066] Examples of the phenol-based curing accelerator include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, naphthol novolac resin, aminotriazine novolac resin, novolac resin, and trisphenylmethane-type phenol novolac resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F; resol-type phenolic resins; and allylphenol resins.

[0067] When a curing accelerator is used, only one type may be used, or two or more types may be used in combination. When a curing accelerator is used, the amount thereof is, for example, 0.1 to 20 mass %, preferably 0.1 to 5 mass %, and more preferably 0.2 to 4.5 mass %, based on the total amount of non-volatile components other than the thermally conductive particles.

[0068] (Resin containing mesogenic structure) The thermosetting resin composition of the present embodiment preferably contains, in addition to the epoxy resin, a resin having a mesogen structure and a weight average molecular weight of 500 or more. This can further improve the thermal conductivity (heat dissipation property). In this specification, this resin is also referred to as a "mesogen structure-containing resin."

[0069] The mesogen structure-containing resin preferably includes a phenoxy resin. That is, the mesogen structure-containing resin preferably includes a phenoxy resin containing a mesogen structure. In the narrow sense, "phenoxy resin" refers to a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin. In this specification, however, the term "phenoxy resin" also includes polymers (phenoxy resins in the broad sense) obtained by subjecting polyfunctional epoxy resins to a polyaddition reaction with polyfunctional phenols.

[0070] Hereinafter, a specific description will be given of the case where the mesogen structure-containing resin is a mesogen structure-containing phenoxy resin. An example of a mesogenic structure-containing phenoxy resin is one that contains a structural unit derived from a phenol compound and a structural unit derived from an epoxy compound in the molecule, and at least one of these structural units contains a compound having a mesogenic structure. Other examples of the mesogen structure-containing phenoxy resin include those that contain structural units derived from a mesogen structure-containing phenol compound in the molecule.

[0071] As an example, a mesogenic structure-containing phenoxy resin can be obtained by reacting a polyfunctional phenol compound having two or more hydroxy groups in the molecule with a polyfunctional epoxy compound having two or more epoxy groups in the molecule. That is, the mesogenic structure-containing phenoxy resin may contain a reaction compound of a polyfunctional phenolic compound and a polyfunctional epoxy compound, either or both of which have a mesogenic structure.

[0072] As another example, a mesogen structure-containing phenoxy resin can be obtained by subjecting a mesogen structure-containing phenol compound having two or more phenol groups in the molecule to an addition polymerization reaction in epichlorohydrin. That is, the mesogenic structure-containing phenoxy resin may contain an addition polymer of a mesogenic structure-containing phenol compound.

[0073] The mesogenic structure-containing phenoxy resin can be produced without a solvent or in the presence of a reaction solvent. As the reaction solvent, an aprotic organic solvent such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, sulfolane, cyclohexanone, etc. can be suitably used. After the reaction is completed, the resin can be obtained as a solution in a suitable solvent by performing solvent replacement, etc. In addition, the phenoxy resin obtained by the solvent reaction can be made into a solid resin without the solvent by performing a solvent removal treatment using an evaporator, etc.

[0074] As a reaction catalyst that can be used in the production of the mesogenic structure-containing phenoxy resin, a conventionally known polymerization catalyst, for example, an alkali metal hydroxide, a tertiary amine compound, a quaternary ammonium compound, a tertiary phosphine compound, a quaternary phosphonium compound, etc., can be suitably used.

[0075] The mesogenic structure has, for example, a structure represented by the following general formula (1) or (2). -A 11 -xA 12 - (1) -xA 11 -x- ··(2) In the general formula (1) and the general formula (2), A 11 and A 12 each independently represents an aromatic group, a fused aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and each x independently represents a direct bond or a divalent linking group selected from the group consisting of -O-, -S-, -C=C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH=N-, -CH=NN=CH-, -N=N-, and -N(O)=N-.

[0076] A 1 , A 2are each independently selected from a hydrocarbon group having 6 to 12 carbon atoms and a benzene ring, a hydrocarbon group having 10 to 20 carbon atoms and a naphthalene ring, a hydrocarbon group having 12 to 24 carbon atoms and a biphenyl structure, a hydrocarbon group having 12 to 36 carbon atoms and having three or more benzene rings, a hydrocarbon group having 12 to 36 carbon atoms and a condensed aromatic group, and an alicyclic heterocyclic group having 4 to 36 carbon atoms. 1 , A 2 may be unsubstituted or may be a derivative having a substituent.

[0077] A in the mesogenic structure 1 , A 2 Specific examples of the alkyl group include phenylene, biphenylene, naphthylene, anthracenylene, cyclohexyl, pyridyl, pyrimidyl, thiophenylene, etc. These may be unsubstituted or may be derivatives having a substituent such as an aliphatic hydrocarbon group, a halogen group, a cyano group, or a nitro group.

[0078] As x corresponding to the bonding group (linking group) in the mesogenic structure, for example, a direct bond or a divalent substituent selected from the group consisting of -C=C-, -C≡C-, -CO-O-, -CO-NH-, -CH=N-, -CH=NN=CH-, -N=N- or -N(O)=N- is preferred. Here, a direct bond is a single bond or an A 1 and A 2 are linked to each other to form a ring structure. For example, the structure represented by the above general formula (1) may contain a naphthalene structure.

[0079] When the mesogen structure-containing phenoxy resin is obtained by the reaction of a polyfunctional phenol compound with a polyfunctional epoxy compound, the polyfunctional phenol compound may be, for example, a mesogen structure-containing compound represented by the following general formula (A): The polyfunctional epoxy compound may be, for example, a mesogen structure-containing compound represented by the following general formula (B): These compounds may be used alone or in combination of two or more.

[0080] [ka]

[0081] In general formula (A), R 1 and R 3 each independently represents a hydroxy group; R 2 and R 4 each independently represents one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom; a and c are each an integer from 1 to 3; b and d are each an integer of 0 to 2. However, a+b and c+d are each an integer from 1 to 3. a+c may be 3 or more.

[0082] [ka]

[0083] In general formula (B), R 5 and R 7 each independently represents a glycidyl ether group, R 6 and R 8 each independently represents one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom; e and g each independently represent an integer of 1 to 3; f and h each independently represent an integer of 0 to 2. Here, e+f and g+h are each an integer of 1 to 3.

[0084] R in the general formula (A) and the general formula (B) is the above-mentioned -A 11 -xA 12 -, -xA 11-x- or -x-. In addition, the two benzene rings in the general formula (A) may be bonded to each other to form a condensed ring.

[0085] R 2 , R 4 , R 6 and R 8 Specific examples of each of the groups include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a chlorine atom, a bromine atom, etc. Among these, a hydrogen atom or a methyl group is particularly preferred.

[0086] As the polyfunctional epoxy compound containing a mesogenic structure, for example, an addition polymer of a compound represented by general formula (B) may be used. These may be used alone or in combination of two or more kinds.

[0087] As the polyfunctional phenol compound and the polyfunctional epoxy compound, a polyfunctional phenol compound having three or more hydroxy groups in the molecule and a polyfunctional epoxy compound having two or more epoxy groups in the molecule may be used. That is, the mesogen structure-containing phenoxy resin can contain a branched reaction compound between a polyfunctional phenol compound having three or more hydroxy groups in the molecule and a polyfunctional epoxy compound having two or more epoxy groups in the molecule.

[0088] The polyfunctional phenol compound having three or more hydroxy groups in the molecule can include, for example, polyphenols or polyphenol derivatives. Polyphenol is typically a compound containing three or more phenolic hydroxyl groups in one molecule. In addition, this polyphenol is preferably one having the above-mentioned mesogen structure in the molecule. For example, biphenyl skeleton, phenylbenzoate skeleton, azobenzene skeleton, stilbene skeleton, etc. can be used as the mesogen structure. The polyphenol derivative includes a compound in which a substitutable position of a polyphenol compound having three or more phenolic hydroxy groups and a mesogenic structure is changed to another substituent.

[0089] In this embodiment, the branched reactive compound can be obtained by using one or more of the above-mentioned polyfunctional phenol compounds, including a polyfunctional phenol compound having at least three or more hydroxy groups in the molecule, and one or more of the above-mentioned polyfunctional epoxy resins.

[0090] For example, a combination of a trifunctional phenol compound and a difunctional epoxy compound, or a combination of a trifunctional phenol compound, a difunctional phenol compound and a difunctional epoxy compound may be used. As a trifunctional phenolic compound, for example, resveratrol represented by the following chemical formula can be used.

[0091] [ka]

[0092] As the bifunctional phenol compound, for example, the above R 1 and R 3 In one embodiment, the hydroxy group is bonded to the para position of each benzene ring. In addition, as the bifunctional epoxy compound, 5 and R 7 The glycidyl ether group of the formula (I) bonded to the para position of each benzene ring can be used. In addition, when the bifunctional phenol compound has a naphthalene ring as a condensed ring, R 1 and R 3 The hydroxyl groups of R can be bonded to any one of the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions of the naphthalene ring. 5 and R 7The glycidyl ether groups may be bonded to the 1- and 4-positions, 1- and 5-positions, 1- and 6-positions, 2- and 3-positions, 2- and 6-positions, or 2- and 7-positions of the naphthalene ring.

[0093] A branched reactive compound (branched phenoxy resin) can be obtained by combining a trifunctional phenol compound and a difunctional epoxy compound as described above, or by combining a trifunctional phenol compound, a difunctional phenol compound and a difunctional epoxy compound.

[0094] Among the polyfunctional phenol compounds and the polyfunctional epoxy compounds, bifunctional phenol compounds and bifunctional epoxy compounds may be used either alone or in combination of two or more. That is, the mesogen structure-containing phenoxy resin can contain a linear reaction compound of a difunctional phenol compound having two hydroxy groups in the molecule and a difunctional epoxy compound having two epoxy groups in the molecule.

[0095] As a bifunctional phenolic compound, R 1 and R 3 The hydroxyl group of each of the benzene rings can be bonded to the para position. 5 and R 7 The glycidyl ether group of the formula (I) bonded to the para position of each benzene ring can be used. When the bifunctional phenol compound has a naphthalene ring as a condensed ring, R 1 and R 3 In the case where the hydroxyl group of R is bonded to any one of the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions of the naphthalene ring can be used. From the viewpoint of the thermal conductivity and heat resistance of the molecule, more preferably, a bifunctional phenol compound having a hydroxyl group naphthalene ring at the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions is selected. In addition, when the bifunctional epoxy compound has a naphthalene ring as a condensed ring, R5 and R 7 In the case of epoxy resins having glycidyl ether groups bonded to the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions, the epoxy resins having naphthalene rings having glycidyl ether groups bonded to the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7 ...glycidyl ether groups bonded to the naphthalene rings can be used. By using such a difunctional phenol compound and a difunctional epoxy compound in combination, a linear reaction compound (linear phenoxy resin) can be obtained.

[0096] The branched phenoxy resin and the linear phenoxy resin can have an epoxy group or a hydroxy group at the molecular terminal and an epoxy group or a hydroxy group inside the molecule. By having an epoxy group at the terminal or inside, a crosslinking reaction can be formed, and therefore the heat resistance can be improved. Furthermore, by having a rigid, electron-conjugated, straight-chain structural unit, the heat dissipation characteristics can be improved.

[0097] The weight average molecular weight (Mw) of the mesogen structure-containing resin is usually 500 or more, preferably 500 to 200,000, more preferably 1,000 to 100,000, and further preferably 3,000 to 50,000. Mw is measured by gel permeation chromatography and is expressed as a value converted using a standard polystyrene calibration curve.

[0098] When a mesogen structure-containing resin is used, only one type of mesogen structure-containing resin may be used, or two or more types of mesogen structure-containing resins having different structures, molecular weights, etc. may be used in combination. When a mesogen structure-containing resin is used, the amount thereof is, for example, 1 to 70 mass %, preferably 2 to 50 mass %, and more preferably 3 to 45 mass % of all non-volatile components other than the thermally conductive particles in the composition.

[0099] (Other Ingredients) The thermosetting resin composition of the present embodiment has a λ200 As long as the thermal expansion coefficient is 12 W / (m K) or more, the thermosetting resin composition may contain any optional component other than the above-mentioned components. The thermosetting resin composition of the present embodiment may contain no optional components, may contain only one optional component, or may contain two or more optional components. Examples of the optional components include a silane coupling agent, an antioxidant, and a leveling agent.

[0100] Examples of the silane coupling agent include epoxy-based silane coupling agents, amino-based silane coupling agents, mercapto-based silane coupling agents, ureido-based silane coupling agents, cationic-based silane coupling agents, titanate-based coupling agents, and silicone oil-type coupling agents. Among them, it is preferable to use a silane coupling agent having an epoxy group, an amino group, a mercapto group, a ureido group, or a hydroxyl group as a functional group. Also, from the viewpoint of improving compatibility with the resin component, a silane coupling agent having a non-reactive phenyl group is also preferable.

[0101] Specific examples of silane coupling agents having a functional group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptotriethoxysilane, 3-ureidopropyltriethoxysilane, and the like.

[0102] Examples of silane coupling agents containing a phenyl group include 3-phenylaminopropyltrimethoxysilane, 3-phenylaminopropyltriethoxysilane, N-methylanilinopropyltrimethoxysilane, N-methylanilinopropyltriethoxysilane, 3-phenyliminopropyltrimethoxysilane, 3-phenyliminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylmethoxysilane, and triphenylethoxysilane.

[0103] When a silane coupling agent is used, the amount thereof is, for example, 0.05 to 3 parts by mass, and preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the thermally conductive particles.

[0104] (Linear expansion coefficient of cured product) By designing a thermosetting resin composition so that the linear expansion coefficient of the cured product is an appropriate value, it is possible to further increase the reliability of, for example, a power module including the cured product. Specifically, the linear expansion coefficient α1 at 23 to 40° C. of the cured product obtained by heating the thermosetting resin composition of the present embodiment at 200° C. for 90 minutes is preferably 20 ppm / ° C. or less, more preferably 19 ppm / ° C. or less, and further preferably 18 ppm / ° C. or less. Basically, the smaller α1 is, the better, but from the viewpoint of practical design, it is 13 ppm / ° C. or more. The linear expansion coefficient of the cured product can be known, for example, based on data obtained by thermomechanical analysis (abbreviated as TMA).

[0105] (Glass transition temperature of the cured product) By designing a thermosetting resin composition so that the glass transition temperature of the cured product is an appropriate value, for example, it is possible to further increase the reliability of a power module including the cured product, and for example, it is possible to reduce failures and malfunctions of the power module even when the power module is used continuously in a high-temperature environment. Specifically, the glass transition temperature of the cured product obtained by heating the thermosetting resin composition of the present embodiment at 200° C. for 90 minutes is preferably 180° C. or higher, more preferably 190° C. or higher, and even more preferably 200° C. or higher. From the viewpoint of ease of designing the thermosetting resin composition, the upper limit of the glass transition temperature is preferably 350° C. or lower, more preferably 300° C. or lower. As the glass transition temperature of the cured product, for example, the temperature at the peak top of the loss tangent (tan δ) obtained by measuring the dynamic viscoelasticity of the cured product while increasing the temperature can be used.

[0106] (Properties of the composition) The thermosetting resin composition of the present embodiment is, for example, in the form of a varnish (liquid). The varnish-like (liquid) thermosetting resin composition can be obtained, for example, by putting each of the above-mentioned components into a solvent and dissolving or dispersing each component in the solvent. Specific methods for dissolving / dispersing include ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill, high-speed shear dispersion, and rotation-revolution dispersion.

[0107] The solvent that can be used is not particularly limited. The solvent is typically an organic solvent. Specific examples include methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, toluene, ethyl acetate, hexane, cyclohexane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene glycol, anisole, cellosolve-based, carbinol-based, and N-methylpyrrolidone. The solvent may be used alone or in combination of two or more.

[0108] (Resin sheet) The resin sheet of the present embodiment includes a carrier substrate and a resin layer formed on the carrier substrate and made of the thermosetting resin composition of the present embodiment. Such a resin sheet can be produced, for example, by applying the above-mentioned varnish-like (liquid) thermosetting resin composition onto a carrier substrate.

[0109] Specifically, the resin sheet of the present embodiment can be obtained by applying a varnish-like thermosetting resin composition onto a carrier substrate to obtain a coating film (resin layer), and then performing a solvent removal treatment on the coating film (resin layer). The solvent content in the resin sheet can be 10 mass % or less based on the entire thermosetting resin composition. The solvent removal treatment can be carried out under conditions of, for example, 80 to 200° C. and 1 to 30 minutes.

[0110] Examples of the carrier substrate include polymer films and metal foils. The polymer film is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, release papers such as silicone sheets, and thermoplastic resin sheets having heat resistance such as fluorine-based resins and polyimide resins. The metal foil is not particularly limited, and examples thereof include 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.

[0111] (Resin substrate) The resin substrate of the present embodiment has an insulating layer made of a cured product of a thermosetting resin composition. This resin substrate can be used as a material for a printed circuit board on which electronic components such as LEDs and power modules are mounted.

[0112] (Metal base board) A metal base substrate 100 of this embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing an example of the configuration of a metal base substrate 100. As shown in FIG. As shown in FIG. 1, the metal base substrate 100 may 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 selected from the group consisting of a resin layer made of a 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 in a B-stage state (semi-cured state) before the circuit processing of the metal layer 103, and may be a cured product obtained by curing the thermosetting resin composition after the circuit processing.

[0113] The metal layer 103 is provided on the insulating layer 102 and is to be patterned into a circuit. 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 more preferably a copper layer. By using copper or aluminum, the circuit processability of the metal layer 103 can be improved. The metal layer 103 may be a metal foil available in a plate shape, or a metal foil available in a roll shape.

[0114] The lower limit of the thickness of the metal layer 103 is, for example, 0.01 mm or more, preferably 0.035 mm or more. When the metal layer 103 is appropriately thick, it can be preferably 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 0.5 mm or less. By keeping the thickness below such a value, circuit processability can be improved, and the substrate as a whole can be made thinner.

[0115] The metal substrate 101 has the 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. The metal substrate 101 is, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate, and is preferably a copper substrate or an aluminum substrate, and more preferably a copper substrate. By using a copper substrate or an aluminum substrate, the heat dissipation of the metal substrate 101 can be improved.

[0116] The thickness of the metal substrate 101 can be appropriately set as long as it does not impair the object of the present invention. 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 20.0 mm or less, the workability of the metal base substrate 100 can be improved in the outer shape processing, cutting processing, and the like. 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 having a thickness of 0.01 mm or more, the heat dissipation properties of the metal base substrate 100 as a whole can be improved.

[0117] The metal base substrate 100 can be used for various substrate applications. Because of its excellent thermal conductivity and heat resistance, it can be used as a printed circuit board that uses an LED or a power module. The metal base substrate 100 may have a metal layer 103 that is circuitized by etching or the like into a pattern. In the 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.

[0118] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. Below, examples of reference forms are given. 1. A thermosetting resin composition comprising an epoxy resin and thermally conductive particles, The thermal conductivity λ of the cured product obtained by heating the thermosetting resin composition at 200°C for 90 minutes at 200°C200 The thermosetting resin composition has a thermal conductivity of 12 W / (m·K) or more. 2. 1. The thermosetting resin composition according to claim 1, The volume resistivity R of the cured product at 200°C 200 is 1.0 × 10 10 A thermosetting resin composition having a hardness of Ω·m or more. 3. 1. The thermosetting resin composition according to 1. or 2., Further comprising a hardener, The thermosetting resin composition, wherein the curing agent comprises a curing agent (a) that does not generate a hydroxy group upon reaction with an epoxy group. 4. 3. The thermosetting resin composition according to claim 1, The curing agent (a) is a thermosetting resin composition containing one or more compounds selected from the group consisting of polyarylate compounds, active ester compounds, cyanate ester compounds, isocyanate compounds and imidazole compounds. 5. The thermosetting resin composition according to any one of 1. to 4., The thermosetting resin composition, wherein the epoxy resin contains a mesogenic skeleton. 6. The thermosetting resin composition according to any one of 1. to 5., A thermosetting resin composition, wherein a part or all of the epoxy resin is liquid at 23°C. 7. 3. or 4. The thermosetting resin composition according to claim 1, A thermosetting resin composition, wherein an equivalent ratio of the curing agent (a) to the epoxy resin in the thermosetting resin composition is 1.0 to 2.0. 8. The thermosetting resin composition according to any one of 1. to 7., The thermosetting resin composition further comprises a curing accelerator. 9. 1. The thermosetting resin composition according to any one of 1. to 8., The thermosetting resin composition further comprises, in addition to the epoxy resin, a resin having a mesogen structure and a weight average molecular weight of 500 or more. 10. The thermosetting resin composition according to any one of 1. to 9., The thermosetting resin composition, wherein the thermally conductive particles include at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. 11. The thermosetting resin composition according to any one of 1. to 10., The linear expansion coefficient α of the cured product at 23 to 40 ° C. 1 The thermosetting resin composition has a viscosity of 20 ppm / °C or less. 12. The thermosetting resin composition according to any one of 1. to 11., The thermosetting resin composition, wherein the cured product has a glass transition temperature of 180° C. or higher. 13. A carrier substrate; A resin sheet comprising: a resin layer formed on the carrier base and made of the thermosetting resin composition according to any one of 1. to 12. 14. A metal substrate; an insulating layer provided on the metal substrate; a metal layer provided on the insulating layer, A metal base board, wherein the insulating layer is a resin layer made of the thermosetting resin composition described in any one of 1. to 12., or a cured product of the thermosetting resin composition described in any one of 1. to 12. EXAMPLES

[0119] The embodiments of the present invention will be described in detail based on examples and comparative examples. However, the present invention is not limited to the examples.

[0120] <Production of Thermosetting Resin Composition (Varnish Form)> Each component shown in Table 1 was added to MEK (methyl ethyl ketone) and stirred. The amount of MEK was appropriately adjusted in consideration of the film thickness in the later evaluation. As a result, a varnish-like resin composition (P) was obtained. The amount of each component in Table 1 is given in parts by mass.

[0121] Details of each component in Table 1 are as follows.

[0122] (Epoxy resin) Epoxy 1: Epoxy resin represented by the following structural formula, product number "EPICLON 830" manufactured by DIC Corporation

[0123] [ka]

[0124] Epoxy 2: Epoxy resin represented by the following structural formula, product number "EPICLON HP-4700" manufactured by DIC Corporation

[0125] [ka]

[0126] (Hardening agent (one that does not produce hydroxyl groups by reaction with epoxy groups)) Cyanate 1: Primaset "PT-30" manufactured by Lonza Active ester 1: DIC, HPC-8000-65T

[0127] (Phenoxy resin (mesogen skeleton-containing resin, etc.)) Phenoxy 1: Bisphenol A type phenoxy resin represented by the following chemical formula (no mesogen structure, "jER-4275" manufactured by Mitsubishi Chemical Corporation)

[0128] [ka]

[0129] Phenoxy 2: Phenoxy resin obtained by the following synthesis method 23.5 parts by mass of epoxy resin (having a mesogen structure, a bifunctional epoxy compound having the following structure, manufactured by Mitsubishi Chemical Corporation, YX4000), 72.5 parts by mass of a bisphenol compound (having a mesogen structure, a bifunctional phenol having the following structure, manufactured by Ueno Pharmaceutical Co., Ltd., HQPOB), 0.04 parts by mass of triphenylphosphine (TPP), and 3.9 parts by mass of a solvent (methyl ethyl ketone) were added to a reactor. Then, the mixture was reacted at a temperature of 120 to 150°C while removing the solvent. The reaction was stopped after confirming that the molecular weight reached the target value by GPC. As a result of the above, a phenoxy resin (phenoxy 2) having a molecular weight of 4500 was obtained.

[0130] [ka]

[0131] Phenoxy 3: Phenoxy resin obtained by the following synthesis procedure Phenoxy 3 was obtained in the same manner as in the synthesis of "Phenoxy 2" above, except that the epoxy resin was 2,6-dihydroxynaphthalene diglycidyl ether having the following structure, and the bisphenol compound was 2,6-dihydroxynaphthalene having the following structure. The weight average molecular weight of the obtained resin was 4800.

[0132] [ka]

[0133] Phenoxy 4: Phenoxy resin obtained by the following synthesis procedure Phenoxy 4 was obtained in the same manner as in the synthesis of "Phenoxy 2" above, except that the epoxy resin was 4,4'-dihydroxybiphenyl diglycidyl ether, and the bisphenol compound was HQ-POB, as shown below. The weight average molecular weight of the obtained resin was 6,400.

[0134] [ka]

[0135] Phenoxy 5: Phenoxy resin obtained by the following synthesis procedure Phenoxy 5 was obtained in the same manner as in the synthesis of "Phenoxy 2" above, except that the epoxy resin was 4,4'-dihydroxybiphenyl diglycidyl ether, and the bisphenol compound was 2,7-dihydroxynaphthalene, as shown below. The weight average molecular weight of the obtained resin was 7700.

[0136] [ka]

[0137] Phenoxy 6: Phenoxy resin obtained by the following synthesis procedure Phenoxy 5 was obtained in the same manner as in the synthesis of "Phenoxy 2" above, except that the epoxy resin was 4,4'-dihydroxybiphenyl diglycidyl ether, and the bisphenol compound was hydroquinone, as shown below. The weight average molecular weight of the obtained resin was 4600.

[0138] [ka]

[0139] (Cure accelerator) Novolac 1: Novolac resin "PR-51470" manufactured by Sumitomo Bakelite Co., Ltd. Imidazole 1: 2-methylimidazole manufactured by Tokyo Chemical Industry Co., Ltd.

[0140] (Thermal Conductive Particles) Granular boron nitride prepared according to the following procedure [procedure] Commercially available boron carbide powder was placed in a carbon crucible and nitrided under nitrogen atmosphere at 2000℃ for 10 hours. Next, commercially available diboron trioxide powder was added to the above nitrided boron nitride powder and mixed in a blender for 1 hour (boron nitride: diboron trioxide = 7:3 (mass ratio)). The resulting mixture was placed in a carbon crucible and fired under a nitrogen atmosphere at 2000°C for 10 hours. Granular boron nitride was obtained in this manner.

[0141] <Preparation of samples for measurement / evaluation (cured products for measurement)>

[0142] The varnish-like resin composition (P) was applied onto a PET film and heat-treated at 100° C. for 30 minutes to produce a thermally conductive sheet in a B-stage (semi-cured state) with a film thickness of 200 μm (0.2 mm). This was peeled off from the PET film and heat-treated at 200° C. for 90 minutes to obtain a thermally conductive sheet cured product. This thermally conductive sheet cured product is hereinafter also referred to as the "cured product for measurement."

[0143] <Measurement of properties of cured product of thermosetting resin composition> (Thermal conductivity at 200℃ λ 200 ) Thermal conductivity is calculated by the formula α×Cp×ρ (α is the thermal diffusion coefficient, Cp is the specific heat, and ρ is the density). Therefore, α, Cp, and ρ were measured to calculate the thermal conductivity. Specifically, the calculation is as follows.

[0144] Measurement of thermal diffusion coefficient α at 200℃ The cured product for measurement was cut into a size of 10 mm x 10 mm with a thickness of about 0.2 mm. This was set in a NETZSCH LFA447 NanoFlash device and held at 200°C in air. The thermal diffusion coefficient α at 200°C was then measured by the laser flash method.

[0145] Measurement of specific heat Cp at 200℃ The specific heat (Cp) of the cured product for measurement at 200° C. was measured by the DSC method in accordance with JIS K 7123 (method for measuring specific heat capacity of plastics).

[0146] Measurement of density ρ The test was carried out in accordance with JIS K 6911 (general test method for thermosetting plastics). The test piece was prepared by cutting the cured product for measurement into a size of 2 cm length × 2 cm width × 0.2 mm thickness. The density ρ was measured at 23°C. Strictly speaking, λ 200 To calculate this, it is necessary to also calculate the density ρ at 200°C. However, due to the difficulty of measurement, the change in density ρ between 23°C and 200°C was ignored.

[0147] Thermal conductivity λ at 200℃ 200 Calculation of Multiplying the α, Cp, and ρ obtained above gives the thermal conductivity λ at 200°C. 200 was calculated.

[0148] (Volume resistivity R at 200℃ 200 ) Measurements were performed in accordance with JIS C 2139. Specifically, a cured product for measurement, processed to an appropriate size, was placed in an oven at 200° C., and the volume resistivity was measured when it reached the target temperature (i.e., 200° C.).

[0149] (Linear expansion coefficient α1 of cured product at 23 to 40°C) The cured product for measurement was processed to a size of 4 mm x 20 mm to prepare a test piece for measuring the linear expansion coefficient. This test piece was set in a TMA (Thermal Mechanical Analyzer) test device (TMA / SS6100 manufactured by Seiko Instruments Inc.). Thermomechanical analysis (TMA) was measured for two cycles under the conditions of a heating rate of 5°C / min, a load of 0.05 N, tension mode, and a measurement temperature range of 30 to 320°C. Of the obtained results, the average value of the linear expansion coefficient in the planar direction (XY direction) in the range of 23 to 40° C. was calculated from the information from the second cycle.

[0150] (Glass transition temperature Tg of cured product) The obtained varnish-like resin composition (P) was heat-treated at 100° C. for 30 minutes to produce a thermally conductive sheet in a B-stage state (semi-cured state) having a thickness of 400 μm. Next, this thermally conductive sheet was heat-treated at 200° C. for 90 minutes to obtain a cured thermally conductive sheet. The glass transition temperature (Tg) of the resulting cured product was measured by DMA (dynamic viscoelasticity measurement) at a heating rate of 5° C. / min and a frequency of 1 Hz. The peak top temperature of tan δ was taken as Tg.

[0151] <Evaluation of heat dissipation in a high-temperature environment simulating that of a generator> The varnish-like resin composition (P) was applied onto a copper foil and heated at 100° C. for 30 minutes to prepare a copper foil with a B-stage (semi-cured) resin composition. This copper foil was cut into a size of 100 mm x 100 mm, and was hardened while being bonded to a 3 mm thick SUS plate under press conditions of 200°C, 25 MPa, and 90 minutes. In this manner, a substrate for evaluating heat dissipation properties was prepared.

[0152] The obtained substrate was placed on a hot plate with the SUS side facing up, and preheated to a surface temperature of 200° C. After confirming that the substrate had reached the target temperature (200° C.), the substrate was quickly moved onto a hot plate that had been preheated to 250° C. At this time, care was taken not to turn the substrate over. After the movement, the temperature rise of the substrate surface was tracked and the time until it reached the saturation point (250°C) was measured. The time to reach the saturation point was evaluated as ⊚ (very good) when it was less than 250 seconds, ◯ (good) when it was between 250 and 300 seconds, and △ (slightly bad) when it was more than 300 seconds. A cured product that reaches its saturation point in a short time can be said to be a cured product that can effectively dissipate heat even in high-temperature environments, such as near a generator.

[0153] The composition, properties, and evaluation results of the thermosetting resin composition are shown in Table 1 below.

[0154] [Table 1]

[0155] Comparing the Example and the Comparative Example, the Example showed better "heat dissipation properties in a high-temperature environment". 200 This is thought to be due to the large size of In addition, R in Examples 1 to 11 200 This clearly shows that, for example, by forming a heat dissipation member in a power module from the cured product of the composition of Examples 1 to 11, it is possible to obtain an effect of reducing leakage current during high-temperature operation of the power module and suppressing leakage current, short circuits, and the like.

[0156] This application claims priority based on Japanese Patent Application No. 2019-115337, filed on June 21, 2019, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0157] 100 Metal base board 101 Metal Substrate 102 Insulating layer 103 Metal layer

Claims

1. A thermosetting resin composition comprising an epoxy resin and thermally conductive particles, and not including metal particles, The thermal conductivity λ of the cured product obtained by heating the thermosetting resin composition at 200°C for 90 minutes at 200°C ２００ is 12 W / (m K) or more, The volume resistivity R of the cured product at 200° C. ２００ is 1.0 x 10 １０ Ω·m or more, The epoxy resin contains a condensed polycyclic aromatic hydrocarbon skeleton, the thermally conductive particles include boron nitride particles; The composition further comprises a mesogen structure-containing phenoxy resin having a weight average molecular weight of 500 or more and a curing agent in addition to the epoxy resin, The curing agent contains a cyanate ester compound as a curing agent (a) that does not generate a hydroxyl group upon reaction with an epoxy group, The content of the epoxy resin is 10% by mass or more and 40% by mass or less of the total non-volatile components other than the thermally conductive particles, the content of the thermally conductive particles is 100 to 400 parts by mass relative to 100 parts by mass of the total non-volatile components other than the thermally conductive particles in the thermosetting resin composition; an equivalent ratio of the curing agent (a) to the epoxy resin in the thermosetting resin composition (the number of moles of reactive functional groups in the curing agent (a) / the number of moles of epoxy groups in the epoxy resin) is 1.0 to 2.0; A thermosetting resin composition, wherein the content of the mesogen structure-containing phenoxy resin is 3 to 70 mass % of all non-volatile components other than the thermally conductive particles in the thermosetting resin composition.

2. The thermosetting resin composition according to claim 1, The thermosetting resin composition further comprises a curing accelerator.

3. The thermosetting resin composition according to claim 1 or 2, The linear expansion coefficient α of the cured product at 23 to 40° C. １ The thermosetting resin composition according to claim 1, wherein the viscosity of the thermosetting resin composition is 20 ppm / ° C. or less.

4. The thermosetting resin composition according to any one of claims 1 to 3, The thermosetting resin composition, wherein the cured product has a glass transition temperature of 180° C. or higher.

5. A carrier substrate; A resin sheet comprising: a resin layer formed on the carrier substrate and made of the thermosetting resin composition according to any one of claims 1 to 4.

6. A metal substrate; an insulating layer provided on the metal substrate; a metal layer provided on the insulating layer, A metal base substrate, wherein the insulating layer is a resin layer made of the thermosetting resin composition according to any one of claims 1 to 4, or a cured product of the thermosetting resin composition according to any one of claims 1 to 4.

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