JP4987161B1 - Insulation material - Google Patents

Abstract

The present invention provides an insulating material that is excellent in thermal conductivity of a cured product after curing and also excellent in moisture resistance of the cured product.
An insulating material according to the present invention is an insulating sheet or an insulating paste used for bonding a thermal conductor 2 having a thermal conductivity of 10 W / m · K or more and a conductive layer 4. The insulating material according to the present invention includes a curable compound having a molecular weight of less than 10,000 and having a cyclic ether group, a curing agent, silica, and an organic compound having an aluminum atom. In 100% by weight of the insulating material, the content of silica is 15% by volume or more and 70% by volume or less.
[Selection] Figure 1

Description

  The present invention relates to an insulating material containing a curable compound, a curing agent, and an inorganic filler. The present invention also relates to 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 recent years, electronic devices and communication devices 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 a fairly high thermal conductivity.

  However, the conventional cured products of insulating adhesive materials described in Patent Documents 1 and 2 may not have sufficiently high thermal conductivity.

  Furthermore, moisture resistance may be lowered in the cured product of the conventional insulating adhesive material. For example, when a pressure cooker test (PCT) of a cured product is performed, the voltage resistance of the cured product may be lowered.

  The objective of this invention is providing the insulating material which is excellent in the heat conductivity of the hardened | cured material after hardening, and is excellent also in the moisture resistance of this hardened | cured material. Moreover, the limited object of this invention is to provide the insulating material which is easy to handle when it is in sheet form.

  Moreover, the objective of this invention is providing the laminated structure which is excellent in the heat conductivity of the hardened | cured material after hardening, and is excellent also in the moisture resistance of this hardened | cured material.

According to a wide aspect of the present invention, it is an insulating sheet used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more and a conductive layer, or the heat conductor or the conductive layer. An insulating material (excluding a prepreg) which is an insulating paste used for bonding the thermal conductor and the conductive layer after being formed into a sheet above, having a molecular weight of less than 10,000 and having a cyclic ether group A curable compound, a curing agent, silica, and an organic compound having an aluminum atom, wherein the curable compound is an epoxy compound having an epoxy group or an oxetane compound having an oxetanyl group, and has the aluminum atom. organic compound, an aluminum-based coupling agent, an insulating material 100 wt%, the content of the silica is 15% by volume or more, 70 bodies % Or less, the insulating material is provided.

  Moreover, according to the wide situation of this invention, the laminated structure using the insulating material mentioned above is provided.

That is, according to the wide aspect of the present invention, a heat conductor having a thermal conductivity of 10 W / m · K or more, an insulating layer laminated on the surface of the heat conductor, and the heat conductor side of the insulating layer A conductive layer laminated on the surface opposite to the above, and the insulating layer is formed by curing an insulating material (except prepreg) in a sheet form, and the insulating material has a molecular weight of 10,000. And a curable compound having a cyclic ether group, a curing agent, silica, and an organic compound having an aluminum atom, and the curable compound has an epoxy compound having an epoxy group or an oxetane having an oxetanyl group. a compound, an organic compound having an aluminum atom, an aluminum-based coupling agent, the insulating material 100 wt%, the content of the silica is 15 Product% or more, 70% by volume or less, the laminated structure is provided.

  In this specification, both the invention related to the insulating material described above and the invention related to the laminated structure described above are disclosed.

Upper Symbol insulating material preferably further comprises a silane coupling agent. The silica is preferably crushed silica. The insulating material includes an organic filler, and the content of the organic filler is preferably 0.1% by volume or more and 3% by volume or less in 100% by weight of the insulating material. The insulating material preferably further includes a polymer having a weight average molecular weight of 10,000 or more. The curing agent preferably contains a basic curing agent. The heat conductor is preferably a metal.

  The insulating material according to the present invention includes a curable compound having a molecular weight of less than 10,000 and having a cyclic ether group, a curing agent, silica, and an organic compound having an aluminum atom, and further 100% by weight of the insulating material. Since the content of the silica in the content is 15% by volume or more and 70% by volume or less, the thermal conductivity of the cured product after curing can be enhanced, and the moisture resistance of the cured product can also be enhanced.

  The laminated structure according to the present invention includes a thermal conductor having a thermal conductivity of 10 W / m · K or more, an insulating layer laminated on the surface of the thermal conductor, and the thermal conductor side of the insulating layer. A conductive layer laminated on the opposite surface, the insulating layer is formed by curing the insulating material in a sheet form, the insulating material has a molecular weight of less than 10,000, and a cyclic ether A curable compound having a group, a curing agent, silica, and an organic compound having an aluminum atom, and the content of the silica in 100% by weight of the insulating material is 15% by volume to 70% by volume. Therefore, the thermal conductivity of the insulating layer can be increased, and the moisture resistance of the insulating layer can be increased.

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

  Hereinafter, the present invention will be described in detail.

  The insulating material according to the present invention is an insulating sheet used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more and a conductive layer, or on the heat conductor or the conductive layer. This is an insulating paste used for bonding the thermal conductor and the conductive layer after being formed into a sheet. The insulating material (insulating paste) according to the present invention may be used by laminating the conductive layer on the insulating material (insulating sheet) formed into a sheet after being formed into a sheet on the heat conductor. The insulating material (insulating paste) according to the present invention may be used by laminating the thermal conductor on a sheeted insulating material (insulating sheet) after being formed into a sheet on the conductive layer.

  The insulating material according to the present invention has a molecular weight of less than 10,000 and a curable compound (B) having a cyclic ether group, a curing agent (C), an inorganic filler (D), and an organic compound having an aluminum atom ( E). The insulating material according to the present invention contains silica as the inorganic filler (D). Further, in 100% by weight of the insulating material, the content of the silica is 15% by volume or more and 70% by volume or less.

  By adopting the above composition in the insulating material according to the present invention, the thermal conductivity of the cured product after curing can be enhanced, and the moisture resistance of the cured product can also be enhanced. Further, by adopting the above composition in the insulating material according to the present invention, a cured product having excellent voltage resistance can be obtained, and further, since the cured product has high moisture resistance, the pressure cooker test (PCT) of the cured product can be obtained. ), The voltage resistance can be maintained high.

  The laminated structure according to the present invention includes a thermal conductor having a thermal conductivity of 10 W / m · K or more, an insulating layer laminated on the surface of the thermal conductor, and the thermal conductor side of the insulating layer. And a conductive layer laminated on the opposite surface. The insulating layer is formed by curing an insulating material in a sheet form. The insulating layer is a cured product obtained by curing the insulating material. The insulating layer is a cured product layer. The insulating layer may be formed by curing an insulating sheet. Further, the insulating material (insulating paste) may be formed into a sheet after the insulating material (insulating paste) is formed into a sheet on the heat conductor or the conductive layer.

  In the laminated structure according to the present invention, the insulating material has a molecular weight of less than 10,000 and a curable compound (B) having a cyclic ether group, a curing agent (C), an inorganic filler (D), and aluminum. And an organic compound (E) having an atom. The insulating material according to the present invention contains silica as the upper inorganic filler (D). Further, in 100% by weight of the insulating material, the content of the silica is 15% by volume or more and 70% by volume or less.

  By adopting the above configuration in the laminated structure according to the present invention, the thermal conductivity of the insulating layer can be increased, and the moisture resistance of the insulating layer can also be increased. Furthermore, since the withstand voltage of the insulating layer is increased and the moisture resistance of the insulating layer is high, the withstand voltage can be maintained high when a pressure cooker test (PCT) of the insulating layer is performed.

  The insulating material preferably further includes a polymer (A) having a weight average molecular weight of 10,000 or more. By using the polymer (A), when the insulating material is in the form of a sheet, the handleability of the sheet-like insulating material is improved. If the insulating material is in the form of a sheet and the handleability is good, a cured product layer (insulating layer) obtained by curing the insulating material in the form of a sheet tends to be uniform and good.

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

(Polymer (A))
The insulating material includes a polymer (A) having a weight average molecular weight of 10,000 or more. The polymer (A) preferably has an aromatic skeleton. In this case, the heat resistance of the cured product increases and the moisture resistance of the cured product also increases. 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. From the viewpoint of further increasing the heat resistance of the cured product and further increasing the moisture resistance of the cured product, the polymer (A) preferably has an aromatic skeleton in the main chain skeleton. 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, and examples thereof 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 thermal cycle resistance and heat resistance of the cured product are further enhanced.

  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 thermoplastic resin or a thermosetting resin. The polymer (A) is preferably a curable resin. The polymer (A) is preferably a thermoplastic resin, and is preferably a thermosetting resin.

  The thermoplastic resin and thermosetting resin are not particularly limited. The thermoplastic resin is not particularly limited, and examples thereof include styrene resin, phenoxy resin, phthalate resin, thermoplastic urethane resin, polyamide resin, thermoplastic polyimide resin, ketone resin, and norbornene resin. The thermosetting resin is not particularly limited, and examples thereof include amino resins, phenol resins, thermosetting urethane resins, epoxy resins, thermosetting polyimide resins, and amino alkyd resins. Examples of the amino resin include urea resin and melamine resin.

  From the viewpoint of suppressing the oxidative deterioration of the cured product, further improving the heat cycle resistance and heat resistance of the cured product, and further reducing the water absorption rate of the cured product, the polymer (A) is a styrene resin or phenoxy resin. Alternatively, an epoxy resin is preferable, a phenoxy resin or an epoxy resin is more preferable, and a phenoxy resin is further preferable. In particular, use of a phenoxy resin or an epoxy resin further increases the heat resistance of the cured product. Moreover, use of a phenoxy resin further lowers the elastic modulus of the cured product and further improves the cold-heat cycle characteristics of the cured product. The polymer (A) may not have a cyclic ether group such as an epoxy group.

  As the styrene resin, specifically, a homopolymer of a styrene monomer, a copolymer of a styrene monomer and an acrylic monomer, or the like can be used. 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.

  Specifically, the phenoxy resin is, for example, a resin obtained by reacting an epihalohydrin with a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with 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. Use of the phenoxy resin having these preferable skeletons further increases the heat resistance of the cured product.

  The epoxy resin is an epoxy resin other than the phenoxy resin. Examples of the epoxy resins include styrene skeleton-containing epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, biphenol type epoxy resins, naphthalene type epoxy resins, and fluorene type epoxy resins. , 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.

  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 handleability of the uncured sheet-like insulating material is further improved, and the heat resistance of the cured product 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 preferably 20% by weight or more in the total 100% by weight of the total resin components (hereinafter, may be abbreviated as the total resin component X) contained in the insulating material and the insulating sheet. It is preferably 30% by weight or more, preferably 60% by weight or less, and more preferably 50% by weight or less. When the content of the polymer (A) is at least the above lower limit, the handleability of the uncured sheet-like insulating material becomes good. 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 curable compound (B), the curing agent (C), the organic compound (E) having an aluminum atom, and other resin components added as necessary. The inorganic filler (D) is not included in all the resin components X.

(Curable compound (B))
The curable compound (B) contained in the insulating material has a molecular weight of less than 10,000 and has a cyclic ether group. Examples of the cyclic ether group include an epoxy group and an oxetanyl group. The curable compound (B) having a cyclic ether group is preferably a curable compound having an epoxy group or an oxetanyl group. 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 voltage resistance 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.

  From the viewpoint of further improving the heat resistance of the cured product, the curable compound (B) preferably has two or more cyclic ether groups.

  From the viewpoint of further improving the heat resistance of the cured product, the content of the curable compound having two or more cyclic ether groups in the total 100% by weight of the curable compound (B) is preferably 70% by weight or more. More preferably, it is 80% by weight or more and 100% by weight or less. The content of the curable compound having two or more cyclic ether groups in the total 100% by weight of the curable compound (B) may be 10% by weight or more and 100% by weight or less. Further, the entire curable compound (B) may be a curable compound having two or more cyclic ether groups.

  The molecular weight of the curable compound (B) is preferably 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 adhesiveness of the surface of the cured product 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 cured product is hard and hard 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 the total resin component X, the content of the curable compound (B) is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 90% by weight or less, more preferably 80% by weight. Hereinafter, it is more preferably 70% by weight or less, particularly preferably 60% by weight or less, and most 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 coating property of the insulating material and the handleability of the sheet-like insulating material are further enhanced.

(Curing agent (C))
The insulating material contains a curing agent (C). The curing agent (C) is not particularly limited as long as the insulating material can be cured. 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) preferably includes an amine curing agent (amine compound), an imidazole curing agent, a phenol curing agent (phenol compound), or an acid anhydride curing agent (acid anhydride), and includes an amine curing agent. More preferred. The acid anhydride curing agent includes an acid anhydride having an aromatic skeleton, a water additive of the acid anhydride or a modified product of the acid anhydride, or an acid anhydride having an alicyclic skeleton, It is preferable to include a water additive of an acid anhydride or a modified product of the acid anhydride.

  The curing agent (C) preferably contains a basic curing agent, a phenol resin having a melamine skeleton or a triazine skeleton, or a phenol resin having an allyl group. Furthermore, from the viewpoint of improving the dispersibility of the inorganic filler (D) and further enhancing the voltage resistance and thermal conductivity of the cured product, the curing agent (C) preferably contains a basic curing agent. Moreover, from the viewpoint of further improving the dispersibility of the inorganic filler (D) and further enhancing the voltage resistance and thermal conductivity of the cured product, the curing agent (C) is an amine curing agent or an imidazole curing agent. More preferably, it includes an amine curing agent, and particularly preferably includes dicyandiamide. Moreover, it is also preferable that a hardening | curing agent (C) contains both a dicyandiamide and an imidazole hardening | curing agent. By using these preferable curing agents, the dispersibility of the inorganic filler (D) in the insulating material is increased, and further, a cured product having an excellent balance of heat resistance, moisture resistance and electrical properties can be obtained. As a result, even if the content of the inorganic filler (D) is small, the thermal conductivity is considerably increased. In particular, when dicyandiamide is used, the adhesiveness between the cured product, the heat conductor, and the conductive layer is considerably increased.

  Examples of the amine curing agent include dicyandiamide, imidazole compounds, diaminodiphenylmethane, and diaminodiphenylsulfone. From the viewpoint of further enhancing the adhesion between the cured product, the heat conductor and the conductive layer, the amine curing agent is more preferably a dicyandiamide or an imidazole curing agent. From the viewpoint of further improving the storage stability of the insulating material, the curing agent (C) preferably includes a curing agent having a melting point of 180 ° C. or higher, and includes an amine curing agent having a melting point of 180 ° C. or higher. Is more preferable.

  Examples of the imidazole curing agent include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl. 2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2- Undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2 '-Methyl Midazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6 [2′-Ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine Isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-dihydroxymethylimidazole Can be mentioned.

  Examples of the phenol curing agent 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, poly ( And di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, and poly (di-p-hydroxyphenyl) methane. From the viewpoint of further enhancing the flexibility of the cured product 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 curing agent 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, and LA-7751. LA-1356 and LA-3018-50P (all of which are manufactured by DIC Corporation), PS6313 and PS6492 (all of which are manufactured by Gunei Chemical Co., Ltd.), and the like.

  Examples of the acid anhydride having an aromatic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride include, for example, a styrene / maleic anhydride copolymer, a benzophenone tetracarboxylic acid anhydride, and a pyromellitic acid anhydride. , Trimellitic anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydroanhydride Examples include phthalic acid, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride.

  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 an alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride is an acid anhydride having a polyalicyclic skeleton, a water additive of the acid anhydride, or the A modified product of an acid anhydride, or an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive of the acid anhydride, or a modified product of the acid anhydride It 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 also preferably methyl nadic acid anhydride or trialkyltetrahydrophthalic anhydride. Use of methyl nadic anhydride or trialkyltetrahydrophthalic anhydride increases the water resistance of the cured product.

In the total 100% by weight of the total resin component X, the content of the curing agent (C) is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 40% by weight or less, 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.

(Inorganic filler (D))
The insulating material includes an inorganic filler (D). By using the inorganic filler (D), the thermal conductivity of the cured product is considerably increased. As for an inorganic filler (D), only 1 type may be used and 2 or more types may be used together. Moreover, the said insulating material contains a silica essential as an inorganic filler (D).

  From the viewpoint of further increasing the thermal conductivity of the cured product, the thermal conductivity of the inorganic filler (D) is preferably 10 W / m · K or more, more preferably 15 W / m · K or more, and further preferably 20 W / m ·. K or more. The upper limit of the thermal conductivity of the inorganic filler (D) is not particularly limited. Inorganic fillers having a thermal conductivity of about 300 W / m · K are widely known, and inorganic fillers having a thermal conductivity of about 200 W / m · K are easily available.

  The inorganic filler (D) other than silica is preferably at least one selected from the group consisting of alumina, synthetic magnesite, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. More preferred is at least one selected from the group consisting of boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. Use of these preferable inorganic fillers further increases the thermal conductivity of the cured product.

  The inorganic filler (D) other than silica is preferably at least one selected from the group consisting of spherical alumina, crushed alumina and spherical aluminum nitride, and more preferably spherical alumina or spherical aluminum nitride. Use of these preferable inorganic fillers further increases the thermal conductivity of the cured product.

  The new Mohs hardness of the inorganic filler (D) is preferably 12 or less, more preferably 9 or less. When the new Mohs hardness of the inorganic filler (D) is 9 or less, the workability of the cured product is further enhanced.

  From the viewpoint of further improving the workability of the cured product, the inorganic filler (D) is preferably at least one selected from the group consisting of synthetic magnesite, crystalline silica, zinc oxide, and magnesium oxide. The new Mohs hardness of these inorganic fillers is 9 or less.

  The inorganic filler (D) may contain a spherical filler (spherical filler), may contain a crushed filler (crushed filler), or may contain a plate-like filler (plate-like filler). Good. It is particularly preferable that the inorganic filler (D) includes a spherical filler. Since spherical fillers can be filled at high density, the use of spherical fillers further increases the thermal conductivity of the cured product.

  Examples of the crushed filler include crushed alumina and crushed silica. The crushing filler is obtained, for example, by crushing a lump-like inorganic substance using a uniaxial crusher, a biaxial crusher, a hammer crusher, a ball mill, or the like. By using the crushed filler, the filler in the cured product tends to be bridged or effectively brought into a close structure. Therefore, the thermal conductivity of the cured product is further increased. Moreover, generally the crushing filler is cheap compared with a normal filler. For this reason, the cost of an insulating material becomes low by use of a crushing filler.

  The silica is preferably crushed silica (crushed silica). By using the crushed silica, the moisture resistance of the cured product is further enhanced, and the voltage resistance is further unlikely to be lowered when the pressure cooker test of the cured product is performed.

  The average particle diameter of the crushed filler is preferably 12 μm or less, more preferably 10 μm or less, and preferably 1 μm or more. When the average particle size of the crushed filler is not more than the above upper limit, the crushed filler can be dispersed with high density in the insulating material, and the voltage resistance of the cured product is further enhanced. When the average particle diameter of the crushed filler is not less than the above lower limit, it becomes easy to fill the crushed filler with high density.

  The aspect ratio of the crushing filler is not particularly limited. The aspect ratio of the crushed filler is preferably 1.5 or more, and preferably 20 or less. Fillers with an aspect ratio of less than 1.5 are relatively expensive and increase the cost of the insulating material. When the aspect ratio is 20 or less, filling of the crushed filler is easy.

  The aspect ratio of the crushed filler can be determined, for example, by measuring the crushed surface of the filler using a digital image analysis particle size distribution measuring apparatus (“FPA” manufactured by Nippon Luft).

  The average particle diameter of the inorganic filler (D) is preferably 0.1 μm or more, and preferably 40 μm or less. When the average particle diameter is not less than the above lower limit, the inorganic filler (D) can be easily filled at a high density. When the average particle size is not more than the above upper limit, the withstand voltage of the cured product is further enhanced.

  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.

  In 100 volume% of the insulating material, the content of the inorganic filler (D) is 15 volume% or more, more preferably 30 volume% or more, still more preferably 50 volume% or more, preferably 90 volume% or less, more preferably 85 volume. % Or less, more preferably 80% by volume or less, particularly preferably 75% by volume or less, and most preferably 70% by volume or less. When the content of the inorganic filler (D) is not less than the above lower limit and not more than the above upper limit, the coating property of the insulating material is improved and the handleability of the sheet-like insulating material is also improved.

  In 100% by volume of the insulating material, the content of silica is 15% by volume or more and 70% by volume or less. When the content of silica is not less than the above lower limit and not more than the above upper limit, the coating property of the insulating material is improved and the handleability of the sheet-like insulating material is also improved. Furthermore, the moisture resistance of the cured product is further increased, and the voltage resistance is less likely to be lowered when a pressure cooker test of the cured product is performed. In 100% by volume of the insulating material, the silica content is preferably 50% by volume or more. When the silica content is 50% by volume or more, the thermal conductivity of the cured product is further increased, the moisture resistance of the cured product is further increased, and when the pressure cooker test of the cured product is performed, The voltage property is further hardly lowered.

(Organic compound having an aluminum atom (E))
The insulating material includes an organic compound (E) having an aluminum atom. By using the organic compound (E) having an aluminum atom, the moisture resistance of the cured product is increased, and the voltage resistance is hardly lowered when a pressure cooker test of the cured product is performed.

  From the viewpoint of further increasing the moisture resistance of the cured product and further suppressing the decrease in voltage resistance when the pressure cooker test of the cured product is performed, the organic compound (E) having an aluminum atom is an aluminum-based compound. A coupling agent is preferred.

  Examples of the organic compound (E) having an aluminum atom include aluminum ethylate, aluminum isopropylate, aluminum diisopropylate mono-sec-butyrate, and aluminum-sec-butyrate.

  Furthermore, as the organic compound (E) having an aluminum atom, an organic compound having a chelate structure and an aluminum atom can also be used. The use of an organic compound having a chelate structure and an aluminum atom increases the storage stability of the insulating material. Examples of organic compounds having a chelate structure and an aluminum atom include aluminum ethyl acetoacetate / diisopropylate, aluminum trisethyl acetoacetate, aluminum alkyl acetoacetate / diisopropylate, aluminum bisethyl acetoacetate / monoacetylacetonate, aluminum trisacetyl Examples include acetonate and acetoalkoxyaluminum diisopropylate.

  The content of the organic compound (E) having an aluminum atom is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, preferably 20% by weight or less in the total 100% by weight of the total resin component X. More preferably, it is 10% by weight or less. When the content of the organic compound (E) having an aluminum atom is not less than the above lower limit, the heat resistance and moisture resistance of the cured product are further increased. When the content of the organic compound (E) having an aluminum atom is not less than the above lower limit and not more than the above upper limit, the moisture resistance of the cured product is further increased, and the withstand voltage when the pressure cooker test of the cured product is performed. Becomes more difficult to decrease. The total resin component X includes an organic compound (E) having an aluminum atom.

(Coupling agent (F))
The insulating material preferably contains a coupling agent (F). The coupling agent (F) does not include an organic compound having an aluminum atom. The coupling agent (F) preferably has no aluminum atom. The coupling agent (F) preferably contains a silane coupling agent. Further, the coupling agent (F) preferably contains a silane, titanium or zircon coupling agent, preferably contains a titanium or zircon coupling agent, and further comprises a titanium coupling. It is preferable that an agent is included. The use of a titanium or zircon coupling agent significantly increases the water and moisture resistance of the cured product and the adhesion of the cured material of the insulating material to the object to be bonded, particularly to the conductive layer formed of copper. Sex is considerably higher. Furthermore, use of a titanium-based or zircon-based coupling agent also increases the heat resistance of the cured product. In addition, the use of a titanium-based or zircon-based coupling agent suppresses the aggregation of the inorganic filler (D) and further increases the thermal conductivity and voltage resistance of the cured product. As for a coupling agent (F), only 1 type may be used and 2 or more types may be used together.

  When the coupling agent (F) is a silane coupling agent (silane coupling agent), the coupling agent (F) is an aminosilane coupling agent, an imidazole silane coupling agent, or a vinyl silane coupling. And an epoxy silane coupling agent. By using the silane coupling agent, aggregation of the inorganic filler (D) is suppressed, and the thermal conductivity and voltage resistance of the cured product are further enhanced. As for a silane coupling agent, only 1 type may be used and 2 or more types may be used together.

  The coupling agent (F) may be a titanium-based coupling agent or a zircon-based coupling agent. From the viewpoint of further improving the heat resistance and moisture resistance of the cured product, the coupling agent (F) 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. 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 manufactured by Ajinomoto Fine Techno Co., Ltd.) Etc. 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.

  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 total 100% by weight of the total resin component X, the content of the coupling agent (F) is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, preferably 20% by weight or less, more preferably Is 10% by weight or less. When the content of the coupling agent (F) is not less than the above lower limit, the heat resistance and moisture resistance of the cured product are further increased. The heat resistance of the hardened | cured material of an insulating material and the handleability of a sheet-like insulating material become it still higher that content of a coupling agent (F) is below the said upper limit. Furthermore, when the content of the coupling agent (F) is not less than the above lower limit and not more than the above upper limit, the aggregation of the inorganic filler (D) is further suppressed, and the thermal conductivity and voltage resistance of the cured product are further improved. Get higher. The total resin component X includes a coupling agent (F).

(Organic filler (G))
The insulating material preferably contains an organic filler (G). The organic filler (G) has a relatively high flexibility. Therefore, by using the organic filler (G), the moisture resistance of the cured product is further increased, and the voltage resistance is hardly further lowered when the pressure cooker test of the cured product is performed.

  The organic filler (G) is preferably insoluble particles including a repeating structure formed of monomers. The monomer is preferably an acrylic monomer or a styrene monomer. As for an acryl-type monomer and a styrene-type monomer, only 1 type may respectively be used and 2 or more types may be used together.

  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, Butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate Can be mentioned. As for the said acrylic monomer, only 1 type may be used and 2 or more types may be used together.

  Examples of the styrene monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethylstyrene And 3,4-dichlorostyrene. Only one type of styrenic monomer may be used, or two or more types may be used in combination.

  The organic filler (G) preferably has a core-shell structure. Use of the organic filler having a core-shell structure further increases the heat resistance of the cured product. The organic filler having a core-shell structure has a core layer and a shell layer covering the core layer. The core layer and the shell layer covering the core layer are preferably acrylic compounds.

  The organic filler (G) is preferably a composite filler containing a compound having a skeleton in which oxygen atoms are directly bonded to silicon atoms and an organic substance. In this case, the heat resistance of the cured product is further increased.

  The core layer preferably contains a compound having a skeleton in which oxygen atoms are directly bonded to silicon atoms. The shell layer preferably contains an organic substance. The organic filler (G) is preferably a composite filler having a core layer containing a compound having a skeleton in which an oxygen atom is directly bonded to the silicon atom, and a shell layer containing the organic substance.

  The compound having a skeleton in which an oxygen atom is directly bonded to the silicon atom is preferably a siloxane polymer. The organic material is preferably an acrylic compound.

  The average particle diameter of the organic filler (G) is preferably 0.1 μm or more, preferably 40 μm or less, more preferably 20 μm or less. When the average particle diameter of the organic filler (G) is not less than the above lower limit, the organic filler (G) can be easily filled at a high density. When the average particle diameter of the organic filler (G) is not more than the above upper limit, the heat resistance of the cured product is further increased.

  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.

  In 100% by volume of the insulating material, the content of the organic filler (G) is preferably 0.01% by volume or more, more preferably 0.1% by volume or more, preferably 10% by volume or less, more preferably 5% by volume or less. More preferably, it is 3% by volume or less. When the content of the organic filler (G) is not less than the above lower limit and not more than the above upper limit, the moisture resistance of the cured product is further increased, and the withstand voltage is further reduced when the pressure cooker test of the cured product is performed. It becomes difficult to do.

(Dispersant)
The insulating material preferably contains a dispersant. Use of the dispersant further increases the thermal conductivity and voltage resistance 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 voltage resistance of the cured product are 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 sheet-like insulating material is further enhanced. When the pKa of the functional group is not more than the above upper limit, the function of the dispersant is sufficiently exhibited, and the thermal conductivity and voltage resistance 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 voltage resistance of the cured product are further increased.

  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, the aggregation of the inorganic filler (D) is suppressed, and the thermal conductivity and voltage resistance of the cured product are further enhanced.

(Other ingredients)
In order to further improve the handleability, 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 is self-supporting at room temperature (23 ° C.) and has excellent handleability. 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.

  Furthermore, the insulating material may contain a tackifier, a plasticizer, a thixotropic agent, a flame retardant, a photosensitizer, a colorant, and the like as necessary.

(Other details of insulation materials)
The insulating material 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. Further, the thickness of the sheet-like insulating material when the insulating material is formed into a sheet is not particularly limited. The thickness of the insulating sheet and the sheet-like insulating material is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 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 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 thermal conductivity of the cured product of the insulating material is preferably 0.3 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 thermal conductivity of the cured product.

  The dielectric breakdown voltage of the cured product of the insulating material is preferably 40 kV / mm or more, more preferably 50 kV / mm or more, still more preferably 60 kV / mm or more, and particularly preferably 70 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.

(Other details of 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. The thermal conductor having a thermal conductivity of 10 W / m · K or more is preferably a metal, and more preferably 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 (“E1256” manufactured by Mitsubishi Chemical Corporation, Mw = 51000, Tg = 98 ° C.)
(2) High heat resistance phenoxy resin (“FX-293” manufactured by Nippon Steel Chemical Co., Ltd., Mw = 43700, Tg = 163 ° C.)
(3) Epoxy group-containing styrene resin (“Marproof G-1010S” manufactured by NOF Corporation, Mw = 100000, Tg = 93 ° C.)

[Curable compound (B)]
(1) Bisphenol A liquid epoxy resin ("Epicoat 828US" manufactured by Mitsubishi Chemical Corporation, Mw = 370)
(2) Bisphenol F type liquid epoxy resin (“Epicoat 806L” manufactured by Mitsubishi Chemical Corporation, Mw = 370)
(3) Fluorene skeleton epoxy resin (Osaka Gas Chemical Co., Ltd. “Oncoat EX1011”, Mw = 486)
(4) Oxetane resin containing a benzene skeleton (“Ethanacol OXTP” manufactured by Ube Industries, Ltd., Mw = 362.4)
(5) Hexahydrophthalic acid skeleton liquid epoxy resin (“AK-601” manufactured by Nippon Kayaku Co., Ltd., Mw = 284)
(6) Bisphenol A type solid epoxy resin ("1003" manufactured by Mitsubishi Chemical Corporation, Mw = 1300)

[Curing agent (C)]
(1) Alicyclic skeleton acid anhydride (“MH-700” manufactured by Shin Nippon Rika Co., Ltd.)
(2) Aromatic skeleton acid anhydride ("SMA Resin EF60" manufactured by Sartomer Japan)
(3) Biphenyl skeleton phenol resin (“MEH-7851-S” manufactured by Meiwa Kasei Co., Ltd.)
(4) Triazine skeleton phenol resin (“Phenolite KA-7052-L2” manufactured by DIC)
(5) Dicyandiamide ("DICY7" manufactured by Mitsubishi Chemical Corporation)
(6) Isocyanur-modified solid dispersion type imidazole (imidazole curing accelerator, “2MZA-PW” manufactured by Shikoku Kasei Kogyo Co., Ltd.)

[Inorganic filler (D)]
(1) 8 μm silica (spherical silica, “MSS-7” manufactured by Tatsumori, average particle diameter 8 μm, thermal conductivity 10 W / m · K, new Mohs hardness 9)
(2) 10 μm silica (crushed silica, “CMC-1” manufactured by Tatsumori, average particle diameter 10 μm, thermal conductivity 10 W / m · K, new Mohs hardness 9)
(3) 5 μm silica (crushed silica, “VX-S2” manufactured by Tatsumori, average particle diameter 5 μm, thermal conductivity 10 W / m · K, new Mohs hardness 9)
(4) 5 μm alumina (crushed alumina, “LT300C” manufactured by Nippon Light Metal Co., Ltd., average particle size 5 μm, thermal conductivity 36 W / m · K, new Mohs hardness 12)
(5) 6 μm aluminum nitride (crushed aluminum nitride, “FLC” manufactured by Toyo Aluminum Co., Ltd., average particle diameter 6 μm, thermal conductivity 200 W / m · K, new Mohs hardness 11)

[Organic compound having an aluminum atom (E)]
(1) Aluminum-sec-butyrate (manufactured by Kawaken Fine Chemical Co., Ltd.)
(2) Acetoalkoxyaluminum diisopropylate (“AL-M” manufactured by Ajinomoto Fine Techno Co.)

[Coupling agent (F)]
(1) Aminosilane coupling agent (“KBM903” manufactured by Shin-Etsu Chemical Co., Ltd.)
(2) Epoxysilane coupling agent (“KBE403” manufactured by Shin-Etsu Chemical Co., Ltd.)

[Organic filler (G)]
(1) 0.1 μm particles (core-shell type silicone-acrylic particles, “P22” manufactured by Asahi Kasei Wacker Silicone Co., Ltd., having an average particle size of 0.1 μm, a core-shell structure and a skeleton in which oxygen atoms are directly bonded to silicon atoms Including core layer and organic matter)
(2) 0.5 μm particles (core-shell type organic particles, “AC-3355” manufactured by Ganz Kasei Co., Ltd., having an average particle diameter of 0.5 μm and a core-shell structure)
(3) 4 μm particles (“GM-0401S” manufactured by Ganz Chemical Co., Ltd., average particle diameter of 4 μm)

[solvent]
(1) Methyl ethyl ketone

(Examples 1-36 and Comparative Examples 1-8)
Using a homodisper type stirrer, each component was blended in the proportions shown in Tables 1 to 5 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 a PET (polyethylene terephthalate) sheet.

(Evaluation)
(1) Handling property A laminated sheet having a PET sheet and an insulating sheet immediately after production formed on the PET sheet is cut into a size of 460 mm × 610 mm, the insulating sheet is peeled off, and the test sample is peeled off. Got.

  The test sample was wound around a round bar having a radius of 0.5 mm and bent by 180 °, and a bending test was performed. From the number of windings at which cracks occur in the test sample, the handleability was determined according to the following criteria.

[Handling criteria]
○ ○: No cracking occurs even when the winding number is 30 times ○: Cracking occurs when the winding number is 5 times or more and 29 times or less ×: Cracking occurs when the winding number is 4 times or less

(2) Thermal conductivity The thermal conductivity of the insulating sheet immediately after production was measured using a thermal conductivity meter (“Rapid thermal conductivity meter QTM-500” manufactured by Kyoto Electronics Industry Co., Ltd.). Thermal conductivity was determined according to the following criteria.

[Criteria of thermal conductivity]
○○: Thermal conductivity of 1.5 W / m · K or more ○: Thermal conductivity of 0.3 W / m · K or more, less than 1.5 W / m · K ×: Thermal conductivity of 0.3 W / m · K Less than K

(3) Dielectric breakdown voltage (withstand voltage)
The insulating sheet immediately after production was cut out to 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 (dielectric breakdown voltage before PCT). The dielectric breakdown voltage (voltage resistance) was determined according to the following criteria.

[Criteria for dielectric breakdown voltage (withstand voltage)]
○: 70 kV / mm or more ○: 50 kV / mm or more, less than 70 kV / mm ×: less than 50 kV / mm

(4) Dielectric breakdown voltage after pressure cooker test (PCT) (withstand voltage)
The insulating sheet immediately after production was cut out to 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.

  A pressure cooker test (PCT) was performed by treating the obtained cured product for 250 hours under conditions of 120 ° C. and 100% RH.

  Using a withstand voltage tester (MODEL7473, manufactured by EXTECH Electronics), an alternating voltage was applied so that the voltage increased at a rate of 1 kV / sec between the cured products of the insulating sheet after PCT. The voltage at which the cured product of the insulating sheet was broken was defined as the dielectric breakdown voltage. The dielectric breakdown voltage (voltage resistance) after PCT was determined according to the following criteria.

[Criteria for dielectric breakdown voltage (withstand voltage)]
○: Dielectric breakdown voltage after PCT is 70% or more of dielectric breakdown voltage before PCT ○: Dielectric breakdown voltage after PCT is 30% or more and less than 70% of dielectric breakdown voltage before PCT ×: After PCT The breakdown voltage is less than 30% of the breakdown voltage before PCT

  The results are shown in Tables 1 to 5 below. In Table 5 below, * 1 indicates that the composition was not cured, and “-” indicates that it was not evaluated. Moreover, in the following Tables 1-5, content (volume%) of a silica and content (volume%) of an organic filler (G) show the ratio in 100 volume% of insulating sheets.

  In Example 19 using crushed silica and Example 29 using spherical silica, the evaluation results of the dielectric breakdown voltage after PCT are both “◯◯”, but Example 19 is the Example. The evaluation result of the dielectric breakdown voltage after PCT was higher than 29.

  In Example 1 using the organic filler (G) and Example 19 not using the organic filler (G), the dielectric breakdown voltage evaluation results after PCT are both “◯◯”. The numerical value of the evaluation result of the dielectric breakdown voltage after PCT was higher than that in Example 19.

  In Example 20 using the coupling agent (F) and Example 19 not using the coupling agent (F), the evaluation results of the dielectric breakdown voltage after PCT are both “◯◯”. The numerical value of the evaluation result of the dielectric breakdown voltage after PCT was higher in Example 20 than in Example 19.

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

Claims (7)

It is an insulating sheet used for bonding a heat conductor having a thermal conductivity of 10 W / m · K or more and a conductive layer, or the heat conductor after being formed into a sheet on the heat conductor or the conductive layer. An insulating material (excluding a prepreg) that is an insulating paste used to bond a conductor and the conductive layer,
A curable compound having a molecular weight of less than 10,000 and having a cyclic ether group;
A curing agent;
Silica,
An organic compound having an aluminum atom,
The curable compound is an epoxy compound having an epoxy group or an oxetane compound having an oxetanyl group,
The organic compound having an aluminum atom is an aluminum coupling agent,
The insulating material whose content of the said silica is 15 volume% or more and 70 volume% or less in 100 weight% of insulating materials. The insulating material according to claim 1, further comprising a silane coupling agent. The silica is crushed silica, insulating material according to claim 1 or 2. Contains organic filler,
The insulating material according to claim 1 or 2 , wherein a content of the organic filler is 0.1 vol% or more and 3 vol% or less in 100 wt% of the insulating material. Further look-containing polymer has a weight average molecular weight of 10,000 or more,
The insulating material according to any one of claims 1 to 4 , wherein the polymer is a thermoplastic resin or a thermosetting resin . Wherein the curing agent comprises an amine curing agent, an insulating material according to any one of claims 1-5. The heat conductor is a metal, an insulating material according to any one of claims 1-6.

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