JP2012116985A - Insulating material and laminated structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating material used for bonding a thermal conductor having a thermal conductivity of ≥10 W/m-K to a conductive layer, having high heat releasability and high processability of a cured product after being cured.SOLUTION: This insulating material is used for bonding a thermal conductor 2 having a thermal conductivity of ≥10 W/m-K to a conductive layer 4. The insulating material contains a polymer having a weight average molecular weight of ≥10,000, a curable compound having a molecular weight of <10,000 and an epoxy group or an oxetanyl group, a curing agent, and alumina. The purity of alumina by fluorescent X-ray analysis is ≥90.0% and ≤99.0%.

Description

  The present invention relates to an insulating material used for adhering a thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, and more specifically, the heat dissipation and workability of a cured product after curing. The present invention relates to a high insulating material and a laminated structure using the insulating material.

  In electronic devices and communication devices, printed wiring boards having an insulating layer are used. The insulating layer is formed using a paste-like or sheet-like insulating adhesive material.

  As an example of the above-mentioned insulating adhesive material, the following patent document 1 discloses an insulating adhesive in which a glass cloth is impregnated with an adhesive composition containing an epoxy resin, an epoxy resin curing agent, a curing accelerator, an elastomer and an inorganic filler. A sheet is disclosed.

  Insulating adhesive materials that do not contain glass cloth are also known. For example, the example of Patent Document 2 below includes an insulating adhesive containing bisphenol A type epoxy resin, phenoxy resin, phenol novolak, 1-cyanoethyl-2-phenylimidazole, γ-glycidoxypropyltrimethoxysilane, and alumina. Agents are disclosed.

JP 2006-342238 A JP-A-8-332696

  In the insulating adhesive sheet described in Patent Document 1, a glass cloth is used in order to improve handling properties. With an insulating adhesive sheet including glass cloth, it is difficult to make a thin film, and various processes such as laser processing or drilling are difficult. Moreover, since the heat conductivity of the hardened | cured material of the insulation adhesive sheet containing a glass cloth is comparatively low, sufficient heat dissipation may not be obtained. Furthermore, special impregnation equipment must be prepared for impregnating the glass cloth with the adhesive composition.

  In the insulating adhesive described in Patent Document 2, since glass cloth is not used, the sheet itself is not self-supporting in an uncured state. For this reason, the handling property of the insulating adhesive is low.

  In recent years, electric appliances have been reduced in size and performance. For this reason, in the printed wiring board used for the said electronic device and communication apparatus, multilayering and a thin film are progressing, and the mounting density of an electronic component is high. Along with this, a large amount of heat is easily generated from the electronic components, and the need to dissipate the generated heat is increasing. In order to dissipate heat, the insulating layer of the printed wiring board needs to have high thermal conductivity.

  In order to impart high thermal conductivity to the insulating layer, for example, a filler having high thermal conductivity with a thermal conductivity of 10 W / m · K or more is blended in the insulating adhesive material for forming the insulating layer. The method is generally adopted. Alumina is known as a filler having a relatively high thermal conductivity. However, in the conventional insulating adhesive material containing alumina, the processability of the cured product may be low.

  An object of the present invention is to bond a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, an insulating material having high heat dissipation and workability of a cured product after curing, and the It is to provide a laminated structure using an insulating material.

  A limited object of the present invention is not only high heat dissipation and workability of the cured product after curing, but also a sheet-like insulating sheet, which is excellent in handling properties of the insulating sheet in an uncured state. An insulating material, and a laminated structure using the insulating material are provided.

  According to a wide aspect of the present invention, there is provided an insulating material used for bonding a thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, and a polymer having a weight average molecular weight of 10,000 or more. A curable compound having a molecular weight of less than 10,000 and having an epoxy group or an oxetanyl group, a curing agent, and alumina having a purity by fluorescent X-ray analysis of 90.0% or more and 99.5% or less, An insulating material in which the content of alumina is 20% by volume to 70% by volume in 100% by volume of the insulating material is provided.

  In a specific aspect of the insulating material according to the present invention, the alumina is crushed alumina.

  In another specific aspect of the insulating material according to the present invention, the alumina has an average particle size of 10 μm or less and a maximum particle size of 35 μm or less.

  The insulating material according to the present invention preferably further includes a titanium-based or zircon-based coupling agent.

  In another specific aspect of the insulating material according to the present invention, the insulating material is a sheet-like insulating sheet, and the content of the alumina is 20% by volume or more and 70% by volume or less in 100% by volume of the insulating sheet. It is.

  The laminated structure according to the present invention includes a heat conductor having a thermal conductivity of 10 W / m · K or more, an insulating layer laminated on at least one surface of the heat conductor, and the heat conduction of the insulating layer. A conductive layer laminated on a surface opposite to the surface on which the body is laminated, and the insulating layer is formed by curing an insulating material constituted according to the present invention. The heat conductor is preferably a metal.

  The insulating material according to the present invention has a polymer having a weight average molecular weight of 10,000 or more, a curable compound having a molecular weight of less than 10,000 and having an epoxy group or oxetanyl group, a curing agent, and a purity by fluorescent X-ray analysis of 90. 0.0% or more and 99.5% or less of alumina, and the content of alumina in 100% by volume of the insulating material is 20% by volume or more and 70% by volume or less, so that the insulating material according to the present invention is cured. The heat dissipation and workability of the cured product formed can be improved.

FIG. 1 is a partially cutaway front sectional view schematically showing a laminated structure according to an embodiment of the present invention.

  Details of the present invention will be described below.

  The insulating material according to the present invention is an insulating material used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer. The insulating material according to the present invention includes a polymer (A) having a weight average molecular weight of 10,000 or more, a curable compound (B) having a molecular weight of less than 10,000 and having an epoxy group or oxetanyl group, and a curing agent (C). And alumina (D) having a purity by fluorescent X-ray analysis of 90.0% or more and 99.5% or less. In 100 volume% of the insulating material according to the present invention, the content of alumina (D) is 20 volume% or more and 70 volume% or less.

  By adopting the above composition, the purity of alumina is 90.0% or more and 99.5% or less, and the processability of the cured product of the insulating material can be enhanced by the relatively low purity. Furthermore, in the insulating material according to the present invention, alumina having a relatively high thermal conductivity is used in a content not less than the above lower limit, so that the thermal conductivity of the cured product of the insulating material can be increased. As a result, the heat dissipation of the cured product is increased.

  The insulating material according to the present invention may be a liquid insulating composition or a sheet-like insulating sheet. In order to improve the handleability, the insulating material according to the present invention is preferably a sheet-like insulating sheet. Since the insulating material according to the present invention has the above composition, the handling property of the insulating sheet in an uncured state can be improved.

  Furthermore, by adopting the above composition of the insulating material according to the present invention, the heat resistance and dielectric breakdown characteristics of the cured product can be enhanced.

  The insulating material according to the present invention preferably further includes a titanium-based or zircon-based coupling agent (E) in addition to the components (A) to (D) described above. By using the specific coupling agent (E) together with the components (A) to (D), it is possible to increase the adhesion of the cured product to the conductive layer and the heat conductor, which are members to be bonded. In particular, the present inventor uses a specific coupling agent (E) together with the components (A) to (D) to increase the adhesiveness to a conductive layer formed of copper as a cured product of an insulating material. I found out that I can. Furthermore, the water resistance and moisture resistance of the hardened | cured material of an insulating material can be made high by employ | adopting the said composition containing a coupling agent (E).

  Hereinafter, first, details of each material included in the insulating material according to the present invention will be described.

(Polymer (A))
The polymer (A) contained in the insulating material according to the present invention is not particularly limited as long as the weight average molecular weight is 10,000 or more. From the viewpoint of further improving the heat resistance of the cured product, the polymer (A) preferably has an aromatic skeleton. When the polymer (A) has an aromatic skeleton, the polymer (A) may have an aromatic skeleton in any part of the whole polymer, and may have in the main chain skeleton. , May be present in the side chain. The polymer (A) preferably has an aromatic skeleton in the main chain skeleton. In this case, the heat resistance of the cured product of the insulating material is further increased. As for a polymer (A), only 1 type may be used and 2 or more types may be used together.

  The aromatic skeleton is not particularly limited. Specific examples of the aromatic skeleton include naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and bisphenol A skeleton. Of these, a biphenyl skeleton or a fluorene skeleton is preferable. In this case, the heat resistance of the hardened | cured material of an insulating material becomes still higher.

  As the polymer (A), a curable resin such as a thermoplastic resin and a thermosetting resin can be used. The polymer (A) is preferably a curable resin.

  The thermoplastic resin and thermosetting resin are not particularly limited. Examples of the thermoplastic resin and thermosetting resin include thermoplastic resins such as polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, and polyetherketone. In addition, as the thermoplastic resin and thermosetting resin, thermoplastic polyimide, thermosetting polyimide, benzoxazine, and heat-resistant resin group called super engineering plastics such as a reaction product of polybenzoxazole and benzoxazine, etc. Can be used. As for the said thermoplastic resin and the said thermosetting resin, only 1 type may respectively be used and 2 or more types may be used together. Either one of a thermoplastic resin and a thermosetting resin may be used, and a thermoplastic resin and a thermosetting resin may be used in combination.

  The polymer (A) is preferably an epoxy resin, a styrene polymer, a (meth) acrylic polymer or a phenoxy resin, more preferably an epoxy resin or a phenoxy resin, and further preferably a phenoxy resin. . Use of this preferable polymer makes it difficult for the cured product of the insulating material to undergo oxidative degradation and further increases the heat resistance. In particular, the use of epoxy resin or phenoxy resin further increases the heat resistance of the cured product, and the use of phenoxy resin further increases the heat resistance of the cured product.

  The epoxy resin is preferably an epoxy resin other than a phenoxy resin. Examples of the epoxy resin include styrene skeleton-containing epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin. , Phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, anthracene type epoxy resin, epoxy resin having adamantane skeleton, epoxy resin having tricyclodecane skeleton, and epoxy resin having triazine nucleus in skeleton Etc.

  Specifically, a homopolymer of a styrene monomer, a copolymer of a styrene monomer and an acrylic monomer, or the like can be used as the styrene polymer. Among these, a styrene polymer having a styrene-glycidyl methacrylate structure is preferable.

  Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, and pn-. Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl Examples include styrene and 3,4-dichlorostyrene.

  Examples of the acrylic monomer include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, acrylate-2-ethylhexyl, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, Examples include butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. It is done.

  Specifically, the phenoxy resin is, for example, a resin obtained by reacting an epihalohydrin and a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound and a divalent phenol compound.

  The phenoxy resin comprises a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol A / F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, and a dicyclopentadiene skeleton. It is preferred to have at least one skeleton selected from the group. Among these, the phenoxy resin preferably has at least one skeleton selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol A / F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, and a biphenyl skeleton. Preferably, it has at least one skeleton of a fluorene skeleton and a biphenyl skeleton. By using the phenoxy resin having these preferable skeletons, the heat resistance of the cured product of the insulating material is further increased.

  The phenoxy resin preferably has a polycyclic aromatic skeleton in the main chain. The phenoxy resin more preferably has at least one skeleton of the skeletons represented by the following formulas (11) to (16) in the main chain.

In the above formula (11), R ₁ may be the same or different from each other, and is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom, and X ₁ is a single bond, having 1 to 1 carbon atoms. 7 divalent hydrocarbon group, —O—, —S—, —SO ₂ —, or —CO—.

In the above formula (12), R _1a may be the same or different and is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom, and R ₂ is a hydrogen atom, carbon number 1 10 is a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom, R ₃ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and m is an integer of 0 to 5.

In the above formula (13), R _1b may be the same or different from each other, and is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom, and R ₄ is the same or different from each other. It is a hydrogen atom, a C1-C10 hydrocarbon group, or a halogen atom, and l is an integer of 0-4.

In the above formula (15), _{R 5} and _{R 6} is a hydrogen atom, an alkyl group or a halogen atom having 1 to 5 carbon atoms, _{X 2} is _{-SO 2 -, - CH 2 -} , - C (CH 3) 2 -Or -O-, and k is 0 or 1.

  As the polymer (A), for example, a phenoxy resin represented by the following formula (17) or the following formula (18) is suitably used.

In the above formula (17), A ₁ has a structure represented by any _one of the above formulas (11) to (13), and the structure thereof is the structure represented by the above formula (11) is 0 to 0. 60 mol%, the structure is 5 to 95 mol% of the formula (12), and a structure is 5 to 95 mol% of the formula (13), _{a 2} is a hydrogen atom, or the formula a group represented by (14), _{n 1} is a number of 25 to 500 in average. In the formula (17), the structure represented by the formula (11) may not be included.

In the above formula (18), A ₃ has a structure represented by the above formula (15) or the above formula (16), and n ₂ is a value of at least 21 or more.

  The glass transition temperature Tg of the polymer (A) is preferably 60 ° C. or higher, more preferably 90 ° C. or higher, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. When the Tg of the polymer (A) is not less than the above lower limit, the resin is hardly thermally deteriorated. When the Tg of the polymer (A) is not more than the above upper limit, the compatibility between the polymer (A) and another resin is increased. As a result, the handling property of the insulating sheet in an uncured state is further improved, and the heat resistance of the cured product of the insulating material is further increased.

  When the polymer (A) is a phenoxy resin, the glass transition temperature Tg of the phenoxy resin is preferably 95 ° C or higher, more preferably 110 ° C or higher, preferably 200 ° C or lower, more preferably 180 ° C or lower. When the Tg of the phenoxy resin is not less than the above lower limit, the thermal deterioration of the resin can be further suppressed. When the Tg of the phenoxy resin is not more than the above upper limit, the compatibility between the phenoxy resin and the other resin is increased. As a result, the handling property of the insulating sheet in an uncured state and the heat resistance of the cured product of the insulating material are further enhanced.

  The weight average molecular weight of the polymer (A) is 10,000 or more. The weight average molecular weight of the polymer (A) is preferably 30000 or more, more preferably 40000 or more, preferably 1000000 or less, more preferably 250,000 or less. When the weight average molecular weight of the polymer (A) is not less than the above lower limit, the insulating material is hardly thermally deteriorated. When the weight average molecular weight of the polymer (A) is not more than the above upper limit, the compatibility between the polymer (A) and another resin is increased. As a result, the handling property of the insulating sheet in an uncured state is further improved, and the heat resistance of the cured product of the insulating material is further increased.

  The polymer (A) may be added as a raw material, and is a polymer produced by utilizing a reaction in each step such as stirring, coating and drying at the time of producing the insulating material or insulating sheet of the present invention. There may be.

  The content of the polymer (A) is 20% by weight or more and 60% by weight in a total of 100% by weight of the total resin components (hereinafter sometimes abbreviated as “total resin component X”) contained in the insulating material and the insulating sheet. The following is preferable. The content of the polymer (A) in 100% by weight of the total resin component X is more preferably 30% by weight or more, and more preferably 50% by weight or less. When the content of the polymer (A) is at least the above lower limit, the handling properties of the insulating sheet in an uncured state are further improved. Dispersion | distribution of an inorganic filler (D) becomes easy that content of a polymer (A) is below the said upper limit. The total resin component X refers to the total of the polymer (A), the curable compound (B), the curing agent (C), and other resin components added as necessary. The total resin component X does not contain alumina (D). The total resin component X includes a coupling agent (E).

(Curable compound having epoxy group or oxetanyl group (B))
The curable compound (B) contained in the insulating material according to the present invention is not particularly limited as long as it has a molecular weight of less than 10,000 and has an epoxy group or an oxetanyl group. As the curable compound (B) having an epoxy group or oxetanyl group, a conventionally known epoxy compound or oxetane compound can be used. The curable compound (B) is cured by the action of the curing agent (C). As for a curable compound (B), only 1 type may be used and 2 or more types may be used together.

  The curable compound (B) may contain an epoxy compound (B1) having an epoxy group, or may contain an oxetane compound (B2) having an oxetanyl group.

  From the viewpoint of further improving the heat resistance and dielectric breakdown characteristics of the cured product, the curable compound (B) preferably has an aromatic skeleton.

  Specific examples of the epoxy compound (B1) having an epoxy group include an epoxy monomer having a bisphenol skeleton, an epoxy monomer having a dicyclopentadiene skeleton, an epoxy monomer having a naphthalene skeleton, an epoxy monomer having an adamantane skeleton, and an epoxy having a fluorene skeleton. Examples of the monomer include an epoxy monomer having a biphenyl skeleton, an epoxy monomer having a bi (glycidyloxyphenyl) methane skeleton, an epoxy monomer having a xanthene skeleton, an epoxy monomer having an anthracene skeleton, and an epoxy monomer having a pyrene skeleton. These hydrogenated products or modified products may be used. As for an epoxy compound (B1), only 1 type may be used and 2 or more types may be used together.

  Examples of the epoxy monomer having a bisphenol skeleton include an epoxy monomer having a bisphenol A type, bisphenol F type, or bisphenol S type bisphenol skeleton.

  Examples of the epoxy monomer having a dicyclopentadiene skeleton include dicyclopentadiene dioxide and a phenol novolac epoxy monomer having a dicyclopentadiene skeleton.

  Examples of the epoxy monomer having a naphthalene skeleton include 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7-diglycidyl. Naphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene and the like can be mentioned.

  Examples of the epoxy monomer having an adamantane skeleton include 1,3-bis (4-glycidyloxyphenyl) adamantane and 2,2-bis (4-glycidyloxyphenyl) adamantane.

  Examples of the epoxy monomer having a fluorene skeleton include 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3-methylphenyl) fluorene, and 9,9-bis (4- Glycidyloxy-3-chlorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-bromophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-fluorophenyl) fluorene, 9,9-bis (4-Glycidyloxy-3-methoxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dimethylphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dichlorophenyl) Fluorene and 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) Fluorene, and the like.

  Examples of the epoxy monomer having a biphenyl skeleton include 4,4'-diglycidylbiphenyl and 4,4'-diglycidyl-3,3 ', 5,5'-tetramethylbiphenyl.

  Examples of the epoxy monomer having a bi (glycidyloxyphenyl) methane skeleton include 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyloxynaphthyl) methane 1,8'-bi (3,5-glycidyloxynaphthyl) methane, 1,2'-bi (2,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) Examples include methane and 1,2′-bi (3,5-glycidyloxynaphthyl) methane.

  Examples of the epoxy monomer having a xanthene skeleton include 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene.

  Specific examples of the oxetane compound (B2) having an oxetanyl group include, for example, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, 1,4-benzenedicarboxylate bis [(3- Ethyl-3-oxetanyl) methyl] ester, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, and oxetane-modified phenol novolac. As for an oxetane compound (B2), only 1 type may be used and 2 or more types may be used together.

  The molecular weight of the curable compound (B) is less than 10,000. The molecular weight of the curable compound (B) is preferably 200 or more, more preferably 1200 or less, still more preferably 600 or less, and particularly preferably 550 or less. When the molecular weight of the curable compound (B) is not less than the above lower limit, the volatile property of the curable compound (B) is lowered, and the handling property of the insulating material is further enhanced. When the molecular weight of the curable compound (B) is not more than the above upper limit, the adhesiveness of the cured product is further enhanced. Furthermore, the insulating material is hard and difficult to be brittle, and the adhesiveness of the cured product is further enhanced.

  In the present specification, the molecular weight in the curable compound (B) means a molecular weight that can be calculated from the structural formula when it is not a polymer and when the structural formula can be specified. Means weight average molecular weight.

  In the total 100% by weight of all the resin components X, the content of the curable compound (B) is preferably 10% by weight or more and 60% by weight or less. The content of the curable compound (B) in 100% by weight of the total resin component X is more preferably 20% by weight or more, and more preferably 50% by weight or less. When the content of the curable compound (B) is not less than the above lower limit, the adhesiveness and heat resistance of the cured product are further increased. When the content of the curable compound (B) is not more than the above upper limit, the handling property of the insulating sheet is further enhanced.

(Curing agent (C))
The curing agent (C) contained in the insulating material according to the present invention is not particularly limited as long as the insulating material can be cured. The curing agent (C) is preferably a thermosetting agent. As for a hardening | curing agent (C), only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further improving the heat resistance of the cured product, the curing agent (C) preferably has an aromatic skeleton or an alicyclic skeleton.

  The curing agent (C) is preferably dicyandiamide, a phenol resin, an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride. By using this curing agent, a cured product having an excellent balance of heat resistance, moisture resistance and electrical properties can be obtained. These curing agents are thermosetting agents.

  From the viewpoint of further improving the handleability of the insulating sheet in an uncured state, the curing agent (C) is an acid anhydride, a water additive of the acid anhydride or a modified product of the acid anhydride, or dicyandiamide. It is preferable that

  The phenol resin is not particularly limited. Specific examples of the phenol resin include phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene modified novolak, decalin modified novolak, Examples include poly (di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, and poly (di-p-hydroxyphenyl) methane. Among these, from the viewpoint of further enhancing the flexibility of the insulating material and the flame retardancy of the cured product, a phenol resin having a melamine skeleton, a phenol resin having a triazine skeleton, or a phenol resin having an allyl group is preferable.

  Commercially available products of the phenol resin include MEH-8005, MEH-8010 and MEH-8015 (all of which are manufactured by Meiwa Kasei Co., Ltd.), YLH903 (manufactured by Mitsubishi Chemical Corporation), LA-7052, LA-7054, LA-7751, LA-1356 and LA-3018-50P (all of which are manufactured by DIC), PS6313 and PS6492 (manufactured by Gunei Chemical Co., Ltd.), and the like.

  The acid anhydride having an aromatic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride is not particularly limited. Examples of the acid anhydride having an aromatic skeleton, a water addition of the acid anhydride, or a modified product of the acid anhydride include, for example, a styrene / maleic anhydride copolymer, benzophenone tetracarboxylic acid anhydride, pyromellitic acid anhydride, Trimellitic anhydride, 4,4'-oxydiphthalic anhydride, phenylethynylphthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydrophthalic anhydride Examples include acid, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride. Of these, methyl nadic acid anhydride or trialkyltetrahydrophthalic anhydride is preferable. Use of methyl nadic anhydride or trialkyltetrahydrophthalic anhydride increases the water resistance of the cured product.

  Examples of commercially available acid anhydrides having an aromatic skeleton, water additives of the acid anhydrides, or modified products of the acid anhydrides include SMA Resin EF30, SMA Resin EF40, SMA Resin EF60, and SMA Resin EF80 (any of the above Also manufactured by Sartomer Japan), ODPA-M and PEPA (all manufactured by Manac), Ricacid MTA-10, Ricacid MTA-15, Ricacid TMTA, Ricacid TMEG-100, Ricacid TMEG-200, Ricacid TMEG-300, Ricacid TMEG-500, Ricacid TMEG-S, Ricacid TH, Ricacid HT-1A, Ricacid HH, Ricacid MH-700, Ricacid MT-500, Ricacid DSDA and Ricacid TDA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) PICLON B4400, EPICLON B650, and EPICLON B570 (all manufactured by both DIC Corporation).

The acid anhydride having the alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride,
An acid anhydride having a polyalicyclic skeleton, a water addition of the acid anhydride or a modified product of the acid anhydride, or an acid having an alicyclic skeleton obtained by an addition reaction between a terpene compound and maleic anhydride An anhydride, a water addition of the acid anhydride, or a modified product of the acid anhydride is preferable. By using these curing agents, the flexibility of the cured product and the moisture resistance and adhesion of the cured product are further increased.

  Examples of the acid anhydride having an alicyclic skeleton, a water addition of the acid anhydride, or a modified product of the acid anhydride include methyl nadic acid anhydride, acid anhydride having a dicyclopentadiene skeleton, and the acid anhydride And the like.

  Examples of commercially available acid anhydrides having the alicyclic skeleton, water additions of the acid anhydrides, or modified products of the acid anhydrides include Ricacid HNA and Ricacid HNA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) , And EpiCure YH306, EpiCure YH307, EpiCure YH308H, EpiCure YH309 (all of which are manufactured by Mitsubishi Chemical Corporation) and the like.

  The curing agent (C) is more preferably an acid anhydride represented by any of the following formulas (1) to (4) or dicyandiamide. Moreover, it is preferable that a hardening | curing agent (C) is an acid anhydride represented by either of following formula (1)-(4). By using this preferable curing agent, the flexibility, moisture resistance and adhesion of the cured product are further increased.

  In said formula (4), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group, respectively.

  In order to adjust the curing speed or the physical properties of the cured product, the curing agent and the curing accelerator may be used in combination.

  The said hardening accelerator is not specifically limited. Specific examples of the curing accelerator include tertiary amines, imidazoles, imidazolines, triazines, organic phosphorus compounds, quaternary phosphonium salts and diazabicycloalkenes such as organic acid salts. Examples of the curing accelerator include organometallic compounds, quaternary ammonium salts, metal halides, and the like. Examples of the organometallic compounds include zinc octylate, tin octylate and aluminum acetylacetone complex.

  Examples of the curing accelerator include a high melting point imidazole curing accelerator, a high melting point dispersion type latent curing accelerator, a microcapsule type latent curing accelerator, an amine salt type latent curing accelerator, and a high temperature dissociation type and thermal cation. A polymerization type latent curing accelerator or the like can be used. As for the said hardening accelerator, only 1 type may be used and 2 or more types may be used together.

  Examples of the high melting point dispersion type latent accelerator include amine addition type accelerators in which dicyandiamide or amine is added to an epoxy monomer or the like. Examples of the microcapsule type latent accelerator include a microcapsule type latent accelerator in which the surface of an imidazole, phosphorus or phosphine accelerator is coated with a polymer. Examples of the high-temperature dissociation type and thermal cationic polymerization type latent curing accelerator include Lewis acid salts and Bronsted acid salts.

  The curing accelerator is preferably a high melting point imidazole curing accelerator. By using a high melting point imidazole curing accelerator, the reaction system can be easily controlled, and the curing speed of the insulating material and the physical properties of the cured product can be more easily adjusted. A high-melting point accelerator having a melting point of 100 ° C. or higher is excellent in handleability. Accordingly, the melting accelerator preferably has a melting point of 100 ° C. or higher.

  In a total of 100% by weight of all the resin components X, the content of the curing agent (C) is preferably 10% by weight or more and 40% by weight or less. In the total 100% by weight of all the resin components X, the content of the curing agent (C) is more preferably 12% by weight or more, more preferably 25% by weight or less. When the content of the curing agent (C) is not less than the above lower limit, it is easy to sufficiently cure the insulating material. When the content of the curing agent (C) is not more than the above upper limit, it becomes difficult to generate an excessive curing agent (C) that does not participate in curing. For this reason, the heat resistance and adhesiveness of hardened | cured material become still higher.

(Alumina (D))
Alumina (D) contained in the insulating material according to the present invention has a high thermal conductivity. Therefore, the heat dissipation of the cured product can be enhanced by using alumina (D).

Further, the purity (alumina purity) of alumina (D) contained in the insulating material according to the present invention by fluorescent X-ray analysis is 90.0% or more and 99.5% or less. By using such alumina (D), the workability of the cured product is enhanced. When alumina with a purity exceeding 99.5% is used, it is difficult to sufficiently improve the workability of the cured product. When the purity is 90.0% or more, the heat dissipation of the cured product is sufficiently high. The purity, a content of alumina of the inorganic filler in 100% alumina formulated _{(Al 2 O 3) (%} ). In other words, alumina (D) having a purity by fluorescent X-ray analysis of 90.0% or more and 99.5% or less has an alumina purity of 90.0% or more and 99.5% or less by fluorescent X-ray analysis. It is an inorganic filler. The purity of alumina by fluorescent X-ray analysis is preferably 95% or more, and preferably 99.0% or less.

  The average particle diameter of alumina (D) is preferably 0.3 μm or more, more preferably 0.4 μm or more, preferably 35 μm or less, more preferably 30 μm or less. When the average particle diameter of the alumina (D) is not less than the above lower limit, the alumina (D) can be dispersed with high density, and the heat dissipation of the cured product can be enhanced. When the average particle diameter of the alumina (D) is not more than the above upper limit, the alumina (D) can be dispersed with high density, and the dielectric breakdown characteristics of the cured product are further enhanced. Moreover, high voltage resistance can be maintained even in a thin film having a thickness of 100 μm or less.

  From the viewpoint of further improving the workability and dielectric breakdown characteristics of the cured product, the average particle diameter of alumina (D) is particularly preferably 10 μm or less.

  The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a laser diffraction particle size distribution measuring apparatus. That is, the “average particle size” is a volume average particle size.

  From the viewpoint of further enhancing the voltage resistance of the cured product, the maximum particle size of alumina (D) is preferably 35 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. In the case where the insulating material is an insulating sheet, the maximum particle diameter of alumina (D) is preferably 1/2 or less of the thickness of the insulating sheet from the viewpoint of further enhancing the voltage resistance of the cured product. In order to satisfy the above relationship, alumina treated so as to be substantially free of alumina having a large maximum particle diameter by filtering or classification using a sieve may be used.

  The alumina (D) may be crushed crushed alumina or spherical spherical alumina. Since spherical alumina can be filled at high density, the use of spherical alumina can further improve the heat dissipation of the cured product. From this viewpoint, the alumina (D) is particularly preferably spherical.

  The crushed alumina can be obtained, for example, by crushing massive inorganic substances using a uniaxial crusher, a biaxial crusher, a hammer crusher, a ball mill, or the like. By using the crushed alumina, the crushed alumina in the insulating material tends to have a structure that is bridged or effectively brought close together. Therefore, the thermal conductivity of the cured product of the insulating material can be further enhanced. Also, crushed alumina is generally inexpensive. For this reason, the cost of an insulating material can be reduced by use of crushing alumina.

  The average particle size of the crushed alumina is preferably 12 μm or less. When the average particle size is 12 μm or less, the crushed alumina can be dispersed at a high density in the insulating material, and the dielectric breakdown characteristics of the cured product can be further enhanced. The average particle size of the crushed alumina is more preferably 10 μm or less, and preferably 1 μm or more. When the average particle diameter of the crushed alumina is equal to or more than the above lower limit, it becomes easy to fill the crushed alumina with high density.

  The aspect ratio of crushed alumina is not particularly limited. The aspect ratio of crushed alumina is preferably 1.5 or more and 20 or less. Crushed alumina having an aspect ratio of 1.5 or more is relatively expensive. Therefore, the cost of the insulating material is increased. When the aspect ratio is 20 or less, filling with crushed alumina or crushed silica is easy.

  The aspect ratio of the crushed alumina can be determined by measuring the crushed surface of the crushed alumina using, for example, a digital image analysis type particle size distribution measuring device (trade name: FPA, manufactured by Nippon Luft).

  In 100% by volume of the insulating material and 100% by volume of the insulating sheet, the content of alumina (D) is 20% by volume or more and 70% by volume or less, respectively. For this reason, the heat dissipation of a hardened | cured material and workability become high enough. From the viewpoint of further improving the heat dissipation of the cured product, the content of alumina (D) is preferably 25% by volume or more, more preferably 30% by volume in 100% by volume of the insulating material and 100% by volume of the insulating sheet. That's it. From the viewpoint of further enhancing the handling properties of the insulating sheet in an uncured state and the workability of the cured product, the content of alumina (D) is 60 volumes in 100 volume% of the insulating material and 100 volume% of the insulating sheet, respectively. % Or less is particularly preferable.

(Coupling agent (E))
The insulating material according to the present invention preferably contains a titanium-based or zircon-based coupling agent (E). By using the coupling agent (E), the adhesiveness of the cured product is increased, and in particular, the adhesiveness of the cured product to copper is increased. As for a coupling agent (E), only 1 type may be used and 2 or more types may be used together.

  By using the coupling agent (E) together with the polymer (A), the curable compound (B), the curing agent (C) and the alumina (D), water resistance and moisture resistance of the cured product, and a cured product of the insulating material The adhesion to a member to be bonded is considerably high, and particularly the adhesion to a conductive layer made of copper is considerably high. Further, the use of the coupling agent (E) can suppress the aggregation of the alumina (D) and can further enhance the thermal conductivity and dielectric breakdown characteristics of the cured product.

  The coupling agent (E) may be a titanium-based coupling agent or a zircon-based coupling agent. From the viewpoint of further improving the water resistance and moisture resistance of the cured product and the adhesion of the cured product of the insulating material to the bonding target member, the coupling agent (E) is preferably a titanium-based coupling agent.

  The titanium-based coupling agent contains a titanium atom. Examples of the titanium-based coupling agent include tetramethoxy titanium, tetraethoxy titanium, tetrapropoxy titanium, tetraisopropoxy titanium, and tetrabutoxy titanium. Examples of commercially available titanium coupling agents include Preneact TTS, Preneact 55, Preneact 46B, Preneact 338X, Preneact 238S, Preneact 38S, Preneact 138S, Preneact 41B, Preneact 9SA and Preneact KR44 (all Ajinomoto Finetect). Can be mentioned. Titanium-based coupling agents other than these may be used. Only one type of titanium coupling agent may be used, or two or more types may be used in combination.

  From the viewpoint of further enhancing the water resistance and moisture resistance of the cured product and the adhesion of the cured product of the insulating material to the bonding target member, the coupling agent (E) preferably contains a phosphorus atom, and the following formula (20 It is more preferable to have a structural unit represented by formula (21), and a titanium-based coupling agent represented by any one of the following formulas (21) to (23) is more preferable.

  In said formula (21), n and m show the integer of 1-3, respectively, and the sum total of n and m is 4.

  The zircon-based coupling agent contains a zircon atom. Examples of commercially available zircon coupling agents include NZ01, NZ09, NZ12, NZ33, NZ37, NZ38, NZ39, NZ44, NZ66A, NZ97, NZ38J, KZTPP, and KZ55 (all manufactured by Kenrich Petrochemical). It is done. Zircon coupling agents other than these may be used. Only one type of zircon coupling agent may be used, or two or more types may be used in combination.

  In the insulating material according to the present invention, the content of the coupling agent (E) is preferably 0.01% by weight or more and 20% by weight or less in the total 100% by weight of the total resin component X. In a total of 100% by weight of all resin components X in the insulating material, the content of the coupling agent (E) is more preferably 0.05% by weight or more, and more preferably 10% by weight or less. When the content of the coupling agent (E) is not less than the above lower limit, the adhesiveness and moisture resistance of the cured material of the insulating material to the copper foil are further enhanced. When the content of the coupling agent (E) is not more than the above upper limit, the heat resistance of the cured product of the insulating material and the handleability of the insulating sheet in an uncured state are further enhanced. Furthermore, when the content of the coupling agent (E) is not less than the above lower limit and not more than the above upper limit, the aggregation of alumina (D) can be further suppressed, and the thermal conductivity and dielectric breakdown characteristics of the cured product are further enhanced. be able to.

(Other ingredients)
The insulating material according to the present invention may contain rubber particles. By using the rubber particles, the stress relaxation property and flexibility of the insulating material can be enhanced.

  The insulating material according to the present invention may contain a dispersant. Use of the dispersant can further enhance the thermal conductivity and dielectric breakdown characteristics of the cured product.

  The dispersant preferably has a functional group containing a hydrogen atom having hydrogen bonding properties. When the dispersing agent has a functional group containing a hydrogen atom having hydrogen bonding properties, the thermal conductivity and dielectric breakdown characteristics of the cured product can be further enhanced. Examples of the functional group containing a hydrogen atom having hydrogen bonding include a carboxyl group (pKa = 4), a phosphoric acid group (pKa = 7), a phenol group (pKa = 10), and the like.

  The pKa of the functional group containing a hydrogen atom having hydrogen bonding property is preferably 2 or more, more preferably 3 or more, preferably 10 or less, more preferably 9 or less. When the pKa of the functional group is not less than the lower limit, the acidity of the dispersant does not become too high. Therefore, the storage stability of the insulating material is further enhanced. When the pKa of the functional group is not more than the above upper limit, the function as the dispersant is sufficiently fulfilled, and the thermal conductivity and dielectric breakdown characteristics of the cured product are further enhanced.

  The functional group containing a hydrogen atom having hydrogen bonding properties is preferably a carboxyl group or a phosphate group. In this case, the thermal conductivity and dielectric breakdown characteristics of the cured product are further enhanced.

  Specific examples of the dispersant include a polyester carboxylic acid, a polyether carboxylic acid, a polyacrylic carboxylic acid, an aliphatic carboxylic acid, a polysiloxane carboxylic acid, a polyester phosphoric acid, and a polyether type. Examples thereof include phosphoric acid, polyacrylic phosphoric acid, aliphatic phosphoric acid, polysiloxane phosphoric acid, polyester phenol, polyether phenol, polyacrylic phenol, aliphatic phenol, and polysiloxane phenol. As for the said dispersing agent, only 1 type may be used and 2 or more types may be used together.

  In the total 100% by weight of the total resin component X, the content of the dispersant is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 20% by weight or less, more preferably 10% by weight. % By weight or less. When the content of the dispersant is not less than the above lower limit and not more than the upper limit, aggregation of alumina (D) can be suppressed, and the heat dissipation and dielectric breakdown characteristics of the cured product can be further enhanced.

  In order to further improve handling properties, the insulating sheet may contain a base material such as glass cloth, glass nonwoven fabric, and aramid nonwoven fabric. However, even if the base material is not included, the sheet-like insulating material (insulating sheet) having the above composition has self-supporting property at room temperature (23 ° C.) and excellent handling properties. Therefore, the insulating sheet preferably does not contain a base material, and particularly preferably does not contain glass cloth. When an insulating sheet does not contain the said base material, the thickness of an insulating sheet can be made thin and the thermal conductivity of hardened | cured material can be improved further. Furthermore, when an insulating sheet does not contain the said base material, various processes, such as a laser processing or a drilling process, can also be easily performed to an insulating sheet as needed. In addition, self-supporting means that the shape of a sheet can be maintained and handled as a sheet even if there is no support such as a PET film or copper foil.

  The insulating material according to the present invention may contain a tackifier, a plasticizer, a coupling agent, a thixotropic agent, a flame retardant, a photosensitizer, a colorant, and the like as necessary. Furthermore, the insulating material according to the present invention may contain a filler other than alumina (D).

(Insulation material)
The insulating material according to the present invention is used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer.

  The manufacturing method of the said insulating sheet is not specifically limited. The insulating sheet can be obtained, for example, by forming a mixture obtained by mixing the above-described materials into a sheet shape by a method such as a solvent casting method or an extrusion film forming method. Defoaming is preferred when forming into a sheet.

  The thickness of the insulating sheet is not particularly limited. The thickness of the insulating sheet is preferably 10 μm or more, more preferably 50 μm or more, further preferably 70 μm or more, preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 120 μm or less. When the thickness is not less than the above lower limit, the insulating property of the cured product of the insulating sheet is increased. When the thickness is less than or equal to the above upper limit, the heat dissipation becomes high when the metal body is bonded to the conductive layer.

  The glass transition temperature Tg of the insulating material in the uncured state is preferably 25 ° C. or lower. When the glass transition temperature is 25 ° C. or lower, the insulating material is hard and hardly brittle at room temperature. For this reason, the handleability of the insulating sheet in an uncured state is enhanced.

  The thermal conductivity of the cured material of the insulating material is preferably 0.7 W / m · K or more, more preferably 1.0 W / m · K or more, and further preferably 1.5 W / m · K or more. The higher the thermal conductivity, the higher the heat dissipation of the cured material of the insulating material.

  The dielectric breakdown voltage of the cured product of the insulating material is preferably 40 kV / mm or more, more preferably 60 kV / mm or more, still more preferably 80 kV / mm or more, and particularly preferably 100 kV / mm or more. The higher the dielectric breakdown voltage, the more sufficient insulation can be ensured when the insulating material is used for large current applications such as for power devices.

(Laminated structure)
The insulating material according to the present invention constitutes an insulating layer of a laminated structure in which a conductive layer is laminated on at least one surface of a heat conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer. Is preferably used.

  FIG. 1 shows an example of a laminated structure using an insulating material according to an embodiment of the present invention.

  The laminated structure 1 shown in FIG. 1 includes a heat conductor 2, an insulating layer 3 laminated on the first surface 2a of the heat conductor 2, and a surface on which the heat conductor 2 of the insulating layer 3 is laminated. And a conductive layer 4 laminated on the opposite surface. The insulating layer and the conductive layer are not laminated on the second surface 2b opposite to the first surface 2a of the heat conductor 2. The insulating layer 3 is formed by curing the insulating material according to the present invention. The heat conductivity of the heat conductor 2 is 10 W / m · K or more.

  It is sufficient that the insulating layer and the conductive layer are laminated in this order on at least one surface of the heat conductor, and the insulating layer and the conductive layer are laminated in this order on the other surface of the heat conductor. Good.

  In the laminated structure 1, since the insulating layer 3 has a high thermal conductivity, heat from the conductive layer 4 side is easily transmitted to the thermal conductor 2 through the insulating layer 3. In the laminated structure 1, heat can be efficiently dissipated by the heat conductor 2.

  For example, after bonding a metal body to each conductive layer such as a laminated board or multilayer wiring board provided with copper circuits on both sides, copper foil, copper plate, semiconductor element or semiconductor package via an insulating material, the insulating material is cured. By doing so, the laminated structure 1 can be obtained.

  The heat conductor whose heat conductivity is 10 W / m · K or more is not particularly limited. Examples of the heat conductor having a thermal conductivity of 10 W / m · K or more include aluminum, copper, alumina, beryllia, silicon carbide, silicon nitride, aluminum nitride, and graphite sheet. Especially, it is preferable that the heat conductor whose said heat conductivity is 10 W / m * K or more is copper or aluminum. Copper or aluminum is excellent in heat dissipation.

  The insulating material according to the present invention is suitably used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer of a semiconductor device on which a semiconductor element is mounted on a substrate.

  The insulating material according to the present invention adheres a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer of an electronic component device in which an electronic component element other than a semiconductor element is mounted on a substrate. Also preferably used.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

  The following materials were prepared.

[Polymer (A)]
(1) Bisphenol A type phenoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: E1256, Mw = 51000, Tg = 98 ° C.)
(2) High heat resistance phenoxy resin (manufactured by Toto Kasei Co., Ltd., trade name: FX-293, Mw = 43700, Tg = 163 ° C.)
(3) Epoxy group-containing styrene resin (manufactured by NOF Corporation, trade name: Marproof G-1010S, Mw = 100000, Tg = 93 ° C.)

[Epoxy compound (B1)]
(1) Bisphenol A type liquid epoxy resin (Mitsubishi Chemical Corporation, trade name: Epicoat 828US, Mw = 370)
(2) Bisphenol F type liquid epoxy resin (product name: Epicoat 806L, Mw = 370, manufactured by Mitsubishi Chemical Corporation)
(3) Trifunctional glycidyldiamine type liquid epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: Epicoat 630, Mw = 300)
(4) Fluorene skeleton epoxy resin (manufactured by Osaka Gas Chemical Co., Ltd., trade name: ONCOAT EX1011, Mw = 486)
(5) Naphthalene skeleton liquid epoxy resin (manufactured by DIC, trade name: EPICLON HP-4032D, Mw = 304)
(6) Hexahydrophthalic acid skeleton liquid epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: AK-601, Mw = 284)
(7) Bisphenol A type solid epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: 1003, Mw = 1300)

[Oxetane compound (B2)]
(1) Oxetane resin containing benzene skeleton (manufactured by Ube Industries, trade name: etanacol OXTP, Mw = 362.4)

[Curing agent (C)]
(1) Alicyclic skeleton acid anhydride (manufactured by Shin Nippon Chemical Co., Ltd., trade name: MH-700)
(2) Aromatic skeleton acid anhydride (manufactured by Sartomer Japan, trade name: SMA resin EF60)
(3) Polyalicyclic skeleton acid anhydride (manufactured by Shin Nippon Rika Co., Ltd., trade name: HNA-100)
(4) Terpene-based skeleton acid anhydride (trade name: Epicure YH-306, manufactured by Mitsubishi Chemical Corporation)
(5) Biphenyl skeleton phenolic resin (Madewa Kasei Co., Ltd., trade name: MEH-7851-S)
(6) Allyl group-containing skeletal phenol resin (trade name: YLH-903, manufactured by Mitsubishi Chemical Corporation)
(7) Triazine skeleton phenolic resin (manufactured by DIC, trade name: Phenolite KA-7052-L2)
(8) Melamine skeleton phenolic resin (manufactured by Gunei Chemical Industry Co., Ltd., trade name: PS-6492)
(9) Dicyandiamide (10) Isocyanur-modified solid dispersion type imidazole (imidazole curing accelerator, manufactured by Shikoku Kasei Co., Ltd., trade name: 2MZA-PW)

[Alumina (D)]
(1) Crushed alumina 1 (manufactured by Showa Denko KK, trade name: A-172, average particle size 1.8 μm, maximum particle size 32 μm, purity 99.4% by X-ray fluorescence analysis, thermal conductivity 36 W / m · K New Mohs hardness 12)
(2) Crushed alumina 2 (manufactured by Showa Denko KK, trade name: A-50N, average particle size 1.2 μm, maximum particle size 32 μm, purity 99.0% by X-ray fluorescence analysis, thermal conductivity 36 W / m · K New Mohs hardness 12)
(3) Crushed alumina 3 (manufactured by Showa Denko KK, trade name: A-50-F, average particle size 1.2 μm, maximum particle size 32 μm, purity 98.8% by fluorescent X-ray analysis, thermal conductivity 36 W / m・ K, new Mohs hardness 12)
(4) Crushed Alumina 4 (manufactured by Kinsei Matec Co., Ltd., trade name: Seraph 02050, average particle size 2 μm, maximum particle size 32 μm, purity by fluorescent X-ray analysis 98.2%, thermal conductivity 36 W / m · K, new Morse Hardness 12)

[Fillers other than alumina (D)]
(1) Crushed Alumina A (Nippon Light Metal Co., Ltd., trade name: LS-242C, average particle size 2 μm, purity 99.9% by X-ray fluorescence analysis, thermal conductivity 36 W / m · K, new Mohs hardness 12)
(2) Spherical alumina A (manufactured by Denka Co., Ltd., trade name: DAM-10, average particle size 10 μm, purity 99.9% by X-ray fluorescence analysis, thermal conductivity 36 W / m · K, new Mohs hardness 12)
(3) Talc (Nippon Talc Co., Ltd., trade name: K-1, average particle size 8 μm)

[Coupling agent (E)]
(1) Titanium-based coupling agent 1 (manufactured by Ajinomoto Fine-Techno Co., Ltd., trade name: Plenact 138S)
(2) Titanium coupling agent 2 (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: Plenact 238S)
(3) Titanium coupling agent 3 (manufactured by Ajinomoto Fine-Techno Co., Ltd., trade name: Plenact 338X)
(4) Titanium-based coupling agent 4 (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: Plenact 38S)
(5) Zircon coupling agent (Kenrich Petrochemical Co., Ltd., trade name: NZ38)

[Coupling agents other than coupling agent (E)]
(1) Phenyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE103)

[solvent]
(1) Methyl ethyl ketone

(Examples 1-27 and Comparative Examples 1-7)
Using a homodisper-type stirrer, each raw material was blended in the proportions shown in Tables 1 to 4 below (blending unit is parts by weight) and kneaded to prepare an insulating material.

  The insulating material was applied to a release PET sheet having a thickness of 50 μm so as to have a thickness of 100 μm, and dried in an oven at 90 ° C. for 30 minutes to produce an insulating sheet on the PET sheet.

(Evaluation)
(1) Handling property A laminate sheet having a PET sheet and an insulating sheet formed on the PET sheet was cut into a size of 460 mm x 610 mm to obtain a test sample. Using the obtained test sample, handling properties when the insulating sheet before thermosetting was peeled from the PET sheet at room temperature (23 ° C.) were evaluated according to the following criteria.

[Handling criteria]
○: The insulating sheet is not deformed and can be easily peeled. Δ: The insulating sheet can be peeled, but the sheet is stretched or broken.

(2) Glass transition temperature Using a differential scanning calorimeter “DSC220C” (manufactured by Seiko Instruments Inc.), the glass transition temperature of the insulating sheet in an uncured state was measured at a rate of temperature increase of 3 ° C./min.

(3) Thermal conductivity The thermal conductivity of the insulating sheet was measured using a thermal conductivity meter “quick thermal conductivity meter QTM-500” manufactured by Kyoto Electronics Industry Co., Ltd.

(4) Solder heat resistance test (heat resistance)
An insulating sheet is sandwiched between an aluminum plate having a thickness of 1.5 mm and an electrolytic copper foil having a thickness of 35 μm. Press-cured to form a copper-clad laminate. This copper-clad laminate was cut into a size of 50 mm × 60 mm to obtain a test sample. The obtained test sample was floated in a solder bath at 288 ° C. with the copper foil side facing down, and the time until the copper foil swelled or peeled off was measured and judged according to the following criteria.

[Criteria for solder heat resistance test]
○: No swelling or peeling even after 3 minutes △: Swelling or peeling occurs after 1 minute and before 3 minutes ×: Swelling or peeling occurs after 1 minute

(5) Dielectric breakdown voltage (voltage resistance)
The insulating sheet was cut into a size of 100 mm × 100 mm to obtain a test sample. The obtained test sample was cured in an oven at 120 ° C. for 1 hour and further in an oven at 200 ° C. for 1 hour to obtain a cured product of an insulating sheet. An AC voltage was applied using a withstand voltage tester (MODEL7473, manufactured by EXTECH Electronics) so that the voltage increased at a rate of 1 kV / second between the cured products of the insulating sheet. The voltage at which the cured product of the insulating sheet was broken was defined as the dielectric breakdown voltage.

(6) Workability A copper-clad laminate obtained by the evaluation in (4) above was prepared. This copper-clad laminate was subjected to router processing using a drill having a diameter of 2.0 mm (RA series, manufactured by Union Tool Co., Ltd.) under conditions of a rotational speed of 60000 and a table feed speed of 0.3 m / min. The processing distance until the flash was generated was measured, and the workability was evaluated according to the following criteria.

[Criteria for workability]
A: Processing is possible for 20 m or more without generating burr B: Processing is possible for 10 m or more and less than 20 m without generating burr C: Processing is possible for 5 m or more and less than 10 m without generating burr D: Without generating burr 1m or more and less than 5m can be processed. E: Burrs are generated by processing less than 1m.

  The results are shown in Tables 1 to 4 below. In the following Tables 1 to 4, * 1 represents the content (% by weight) in 100% by weight of the total resin component X. * 2 shows content (volume%) in 100 volume% of insulating sheets. “-” Indicates that evaluation is not performed.

DESCRIPTION OF SYMBOLS 1 ... Laminated structure 2 ... Thermal conductor 2a ... 1st surface 2b ... 2nd surface 3 ... Insulating layer 4 ... Conductive layer

Claims (7)

An insulating material used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer,
A polymer having a weight average molecular weight of 10,000 or more;
A curable compound having a molecular weight of less than 10,000 and having an epoxy group or an oxetanyl group;
A curing agent;
Including alumina having a purity by fluorescent X-ray analysis of 90.0% or more and 99.5% or less,
The insulating material whose content of the said alumina is 20 volume% or more and 70 volume% or less in 100 volume% of insulating materials.   The insulating material according to claim 1, wherein the alumina is crushed alumina.   The insulating material according to claim 1 or 2, wherein the average particle size of the alumina is 10 µm or less and the maximum particle size is 35 µm or less.   The insulating material according to claim 1, further comprising a titanium-based or zircon-based coupling agent. A sheet-like insulation sheet,
The insulating material according to any one of claims 1 to 4, wherein a content of the alumina is 20% by volume or more and 70% by volume or less in 100% by volume of the insulating sheet. A thermal conductor having a thermal conductivity of 10 W / m · K or more;
An insulating layer laminated on at least one surface of the thermal conductor;
A conductive layer laminated on a surface opposite to the surface on which the thermal conductor of the insulating layer is laminated,
The laminated structure in which the said insulating layer is formed by hardening the insulating material of any one of Claims 1-5.   The laminated structure according to claim 6, wherein the heat conductor is a metal.

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