JP4922220B2 - Insulating sheet and laminated structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating sheet capable of having high thermal conductivity and preparing a cured product being excellent on adhesive properties and insulating destruction-resistant characteristics. <P>SOLUTION: In the insulating sheet 3 used to glue the high thermal conductor 4 with thermal conductivity of &ge;10 W/m&times;k on a conductive layer 2, the insulating sheet 3 contains a polymer A with an aromatic structure and weight average molecular weight of &ge;30,000, an epoxy monomer B1 and/or an oxetane monomer B2 with an aromatic structure and weight average molecular weight of &le;600, a curing agent C, and a filler D. Globular filler D1 of 5-30 vol% with average particle sizes of 0.1-0.5 &mu;m, globular filler D2 of 20-60 vol% with average particle sizes of 2-6 &mu;m, and globular filler D3 of 20-60 vol% with average particle sizes of 10-40 &mu;m are included in 100 vol% filler D. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an insulating sheet used for adhering a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, and more particularly, to an insulating sheet having high thermal conductivity and adhesion and insulation. The present invention relates to an insulating sheet that gives a cured product having excellent destructive properties, and a laminated structure using the insulating sheet.

  In recent years, miniaturization and high performance of electric devices have been advanced. Along with this, the mounting density of electronic components is increasing, and the need to effectively dissipate heat generated from electronic components is increasing. Further, in response to the recent increase in environmental awareness, in power device applications such as electric vehicles capable of suppressing environmental loads, it is unavoidable that a high voltage is applied or a large current flows. In this case, a high amount of heat is generated, but in order to cope with the high amount of heat generated, the necessity to dissipate heat more efficiently than ever is increasing.

  As a method of dissipating heat, a method of adhering a high heat conductor such as aluminum having high heat dissipation and a thermal conductivity of 10 W / m · K or more to a heat source is widely adopted. Yes. Further, an insulating adhesive material having an insulating property is used to bond the high thermal conductor to a heat source. Insulating adhesive materials are strongly required to have high thermal conductivity.

  As an example of the above insulating adhesive material, the following Patent Document 1 discloses an insulating material 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. An adhesive sheet is disclosed. In the adhesive composition, it is described that the inorganic filler is preferably blended at a ratio of 3 to 50% by mass.

In Patent Document 2 below, inorganic powder A having an average particle size of 0.1 to 0.9 μm is 15 to 35% by weight, and inorganic powder B having an average particle size of 2.0 to 6.0 μm is 0 to 40% by weight. %, An adhesive having an average particle size of 10.0 to 30.0 μm in an amount of 40 to 80% by weight and 100% by weight in total is disclosed. In this adhesive, the specific inorganic powder having high thermal conductivity and excellent electrical insulation is blended at the specific ratio, thereby improving heat dissipation.
JP 2006-342238 A Japanese Patent No. 2520988

  In the insulating adhesive sheet described in Patent Document 1, it is described that the inorganic filler is preferably blended at the specific ratio. However, Patent Document 1 does not describe what kind of shape and what particle size the inorganic filler is used. Therefore, depending on the shape and particle size of the inorganic filler compounded in the insulating adhesive sheet, the thermal conductivity of the insulating adhesive sheet may be low, and sufficient heat dissipation may not be obtained.

  Furthermore, in the insulating adhesive sheet described in Patent Document 1, a glass cloth is used in order to enhance sheet characteristics such as handling properties. When glass cloth is used, the thermal conductivity of the insulating adhesive sheet is relatively low, and sufficient heat dissipation may not be obtained. On the other hand, it may be difficult to perform various processes such as thinning, laser processing, and drilling. In addition, special impregnation equipment had to be prepared in order to impregnate the glass cloth with the adhesive composition.

  On the other hand, in the adhesive described in Patent Document 2, three types of inorganic powders A to C having different particle sizes are blended. However, for example, when an inorganic powder having an average particle size of more than 0.5 μm and not more than 0.9 μm is used as the inorganic powder A, the inorganic powder B and particles having an average particle size of 2.0 to 6.0 μm are used. Since the diameters were too close, sufficient filling properties could be secured. For this reason, thermal conductivity may decrease, local aggregation of fillers may occur and adhesive strength may decrease, and insulation may not be sufficiently obtained. Moreover, it is sufficient when the blending amount of the inorganic powder B having an average particle size of 2.0 to 6.0 μm is too small and / or when the blending amount of the inorganic powder C having an average particle size of 10 to 30 μm is too large. Fillability may not be ensured. For this reason, thermal conductivity may be lowered, local filler agglomeration may occur and adhesive strength may be reduced, or insulation may not be sufficiently obtained.

  Moreover, depending on the types of resin components other than the inorganic powders A to C blended in the adhesive, the dielectric breakdown characteristics and adhesiveness of the cured product of the adhesive may be reduced.

  An object of the present invention is to adhere a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer in view of the current state of the prior art described above, and has a high thermal conductivity and adhesion. It is an object to provide an insulating sheet that provides a cured product having excellent properties and dielectric breakdown characteristics, and a laminated structure using the insulating sheet.

  A limited object of the present invention is to provide an insulating sheet that has a further higher thermal conductivity and provides a cured product with better dielectric breakdown characteristics, and a laminated structure using the insulating sheet.

  A more limited object of the present invention is to provide an insulating sheet that gives a cured product that has not only high thermal conductivity, excellent adhesion and dielectric breakdown characteristics, but also excellent heat resistance, and lamination using the same It is to provide a structure.

According to the present invention, there is provided an insulating sheet used for bonding a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, having an aromatic skeleton, and having a weight average molecular weight of 30,000. The polymer (A) as described above, an epoxy monomer (B1) having an aromatic skeleton and a weight average molecular weight of 600 or less, and / or an oxetane having an aromatic skeleton and a weight average molecular weight of 600 or less. It contains a monomer (B2), a curing agent (C), and a filler (D), the polymer (A) is a thermosetting resin, and an average particle size of 0 in 100% by volume of the filler (D). .1 to 0.5 μm spherical filler (D1) 5 to 30% by volume, spherical filler (D2) 20 to 60% by volume with an average particle size 2 to 6 μm, and spherical filler (D3) with an average particle size 10 to 40 μm 20-60% by volume is a sphere Filler (D1), (D2) and total (D3) is included respectively in an amount not to exceed 100% by volume, relative to total 100 parts by weight of the total resin component contained in the insulating sheet, the polymer the content of (a) is characterized in der Rukoto the range of 30 to 60 parts by weight, the insulating sheet is provided.

  On the specific situation of the insulating sheet of this invention, the dispersing agent (F) which has a functional group containing the hydrogen atom which has hydrogen bonding property is further contained. It is preferable that pKa of the said functional group of the said dispersing agent (F) is 2-10. When such a dispersant (F) is used, the thermal conductivity and dielectric breakdown characteristics of the cured product of the insulating sheet are further enhanced.

  In the present invention, various fillers can be used as the filler (D), but at least one selected from the group consisting of alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, zinc oxide and magnesium oxide. Species are preferred. When these fillers are used, the thermal conductivity of the cured product of the insulating sheet is further enhanced.

  In a specific aspect of the insulating sheet according to the present invention, the main components of the spherical fillers (D1), (D2), and (D3) are the same.

  Further, in the present invention, various polymers can be used as the polymer (A), but a phenoxy resin is preferable, thereby improving heat resistance. The phenoxy resin preferably has a glass transition temperature Tg of 95 ° C. or higher. In this case, the thermal deterioration of the resin is further suppressed.

  In the present invention, various curing agents can be used as the curing agent (C). Among them, an acid anhydride having a polyalicyclic skeleton, an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive thereof, or a modified product thereof are preferably used. . Furthermore, an acid anhydride represented by any of the following formulas (1) to (3) is more preferably used as the curing agent (C). In these cases, the flexibility, moisture resistance and / or adhesion of the insulating sheet can be further enhanced.

  In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.

  In the present invention, various curing agents can be used as the curing agent (C), and a phenol resin having a melamine skeleton or a triazine skeleton or a phenol resin having an allyl group is preferable. In this case, sheet flexibility and flame retardancy can be further enhanced.

  In the laminated structure according to the present invention, a conductive layer is laminated on at least one surface of a high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer, and the insulating layer is configured according to the present invention. The insulating sheet thus formed is cured.

  In a specific aspect of the laminated structure according to the present invention, the high thermal conductor is a metal.

  According to the present invention, the insulating sheet contains the above components (A) to (D), and the filler (D) contains spherical fillers (D1) having an average particle size of 0.1 to 0.5 μm and an average. Since the spherical filler (D2) having a particle diameter of 1 to 6 μm and the spherical filler (D3) having an average particle diameter of 10 to 40 μm are contained in the specific ratio, the cured product of the insulating sheet has high thermal conductivity. It has excellent adhesion and dielectric breakdown characteristics.

  When the dispersant (F) having a functional group containing a hydrogen atom having hydrogen bonding properties is contained, the thermal conductivity and dielectric breakdown characteristics of the cured product of the insulating sheet can be further enhanced.

  In the laminated structure according to the present invention, a conductive layer is laminated on at least one surface of a high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer, and the insulating layer is configured according to the present invention. Since the formed insulating sheet is cured, heat from the conductive layer side is easily transferred to the high heat conductor through the insulating layer, and heat can be efficiently dissipated by the high heat conductor. Further, in the laminated structure, dielectric breakdown and peeling at the adhesive interface are unlikely to occur.

  As a result of intensive studies to solve the above problems, the inventors of the present application have a polymer (A) having an aromatic skeleton and a weight average molecular weight of 30,000 or more, an aromatic skeleton, and a weight. An epoxy monomer (B1) having an average molecular weight of 600 or less and / or an oxetane monomer (B2) having an aromatic skeleton and a weight average molecular weight of 600 or less, a curing agent (C), and a filler (D), In this specific composition, the filler (D) includes a spherical filler (D1) having an average particle size of 0.1 to 0.5 μm and a spherical filler (D2) having an average particle size of 1 to 6 μm. And a spherical filler (D3) having an average particle diameter of 10 to 40 μm is contained at the above-mentioned specific ratio, thereby having a high thermal conductivity and excellent adhesion and dielectric breakdown characteristics. Give things It found that edge sheet is obtained, thereby forming the basis of the present invention.

  In addition to the above components, the inventors of the present application adopt a composition further including a dispersant (F) having a functional group containing a hydrogen atom having hydrogen bonding properties, thereby improving thermal conductivity and dielectric breakdown characteristics. It has also been found that an insulating sheet giving a more excellent cured product can be obtained.

  Furthermore, the inventors of the present application have high thermal conductivity, excellent adhesion and insulation when the polymer (A) having the above aromatic skeleton and having a weight average molecular weight of 30,000 or more is a phenoxy resin. It has also been found that an insulating sheet that gives a cured product that not only has destructive properties but also has excellent heat resistance can be obtained.

  Details of the present invention will be described below.

  The insulating sheet according to the present invention includes a polymer (A) having an aromatic skeleton and a weight average molecular weight of 30,000 or more, and an epoxy monomer having an aromatic skeleton and a weight average molecular weight of 600 or less ( B1) and / or an oxetane monomer (B2) having an aromatic skeleton and a weight average molecular weight of 600 or less, a curing agent (C), and a filler (D). The insulating sheet according to the present invention preferably further contains, in addition to these components, a dispersant (F) having a functional group containing a hydrogen atom having hydrogen bonding properties.

(Polymer (A))
The polymer (A) contained in the insulating sheet according to the present invention may have an aromatic skeleton in the whole polymer, may be contained in the main chain skeleton, and contained in the side chain. Also good. Since heat resistance is enhanced, the polymer (A) preferably has an aromatic skeleton in the main chain skeleton.

  The aromatic skeleton is not particularly limited, and examples thereof include a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, and an adamantane skeleton. Especially, since heat resistance is further improved, a biphenyl skeleton or a fluorene skeleton is preferable.

  The polymer (A) is not particularly limited, and a thermoplastic resin or a thermosetting resin can be used.

  The thermoplastic resin and the thermosetting resin are not particularly limited. For example, thermoplastic resins such as polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, and polyetherketone, A heat-resistant resin group called super engineering plastics such as plastic polyimide, thermosetting polyimide, benzoxazine, and a reaction product of polybenzoxazole and benzoxazine can be used. These thermoplastic resins and thermosetting resins may be used alone or in combination of two or more. Moreover, a thermoplastic resin and a thermosetting resin may each be used independently, and both may be used together.

  Among the polymers (A), oxidative deterioration can be prevented and the heat resistance is further enhanced, so that a styrene polymer or a phenoxy resin is preferable, and among these, a phenoxy resin is more preferable.

  Specific examples of the styrenic polymer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, 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, 3,4-dichlorostyrene and the like, a styrene monomer homopolymer selected from these, or these monomers and acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, Methyl tacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate Further, a copolymer with an acrylic monomer selected from diethylaminoethyl methacrylate and the like as required can be used. Among these, a styrene polymer having a styrene-glycidyl methacrylate structure can be preferably used.

  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. is there.

  Examples of the phenoxy resin include bisphenol A skeleton, bisphenol F skeleton, bisphenol A / F mixed skeleton, naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton and dicyclopentadiene skeleton. Phenoxy resins having at least one skeleton selected from the group consisting of Among them, since the heat resistance is further enhanced, 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 is used. A phenoxy resin having a fluorene skeleton and / or a biphenyl skeleton is more preferable.

  The phenoxy resin preferably has a polycyclic aromatic skeleton in the main chain. The phenoxy resin more preferably has at least one skeleton among the skeletons represented by the following formulas (4) to (9) in the main chain.

In the above formula (4), 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 element, and X ₁ is a single bond or carbon. It is a group selected from a divalent hydrocarbon group of formulas 1 to 7, —O—, —S—, —SO ₂ —, or —CO—.

In the formula (5), R _1a may be the same as or different from each other, and is a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and R ₂ is a hydrogen atom, It is a group selected from a hydrocarbon group having 1 to 10 carbon atoms or a halogen element, 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 (6), R _1b may be the same as or different from each other, and is a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and R ₄ is the same as each other. Or a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and l is an integer of 0 to 4.

In the above formula (8), R ₅ and R ₆ are selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a halogen atom, and X ₂ is —SO ₂ —, —CH ₂ —, —C ( CH ₃ ) ₂ —, or —O—, and k is a value of 0 or 1.

  As the polymer (A), for example, a phenoxy resin represented by the following formula (10) or the following formula (11) can be suitably used.

In the above formula (10), A ₁ has a structure represented by any of the above formulas (4) to (6), and the structure is 0 to 60 mol of the structure represented by the above formula (4). %, The structure represented by the above formula (5) is 5 to 95 mol%, and the structure represented by the above formula (6) is 5 to 95 mol%, and A ₂ represents a hydrogen atom or the above formula (7 ), And n ₁ is an average value of 25 to 500.

In the above formula (11), A ₃ has a structure represented by the above formula (8) or the above formula (9), and n ₂ has a value of at least 21 or more.

  The glass transition temperature Tg of the polymer (A) is preferably in the range of 60 to 200 ° C. More preferably, it is the range of 90-180 degreeC. If the Tg of the polymer (A) is too low, the resin may be thermally deteriorated. If the Tg is too high, the compatibility with other resins is deteriorated. As a result, the handling property of the insulating sheet and the cured product of the insulating sheet are deteriorated. Heat resistance such as cold cycle resistance and high temperature storage resistance may be reduced.

  When the polymer (A) is a phenoxy resin, the glass transition temperature Tg is preferably 95 ° C. or higher, more preferably 110 to 200 ° C., and even more preferably 110 to 180 ° C. If the Tg of the phenoxy resin is too low, the resin may be thermally deteriorated. If the Tg is too high, the compatibility with other resins deteriorates. As a result, the handling properties of the insulating sheet and the heat resistance of the cured product of the insulating sheet are reduced. Heat resistance such as cycle performance and high temperature resistance may decrease.

  The polymer (A) has a weight average molecular weight of 30,000 or more. The weight average molecular weight of the polymer (A) is preferably in the range of 30,000 to 1,000,000, more preferably in the range of 40,000 to 250,000. If the weight average molecular weight is too small, thermal degradation may occur.If the weight average molecular weight is too large, compatibility with other resins is deteriorated. As a result, the handling properties of the insulating sheet, and the thermal cycle resistance of the cured product of the insulating sheet and Heat resistance such as resistance to high-temperature standing may decrease.

  As a compounding quantity of the said polymer (A), the range of 20-60 weight part is preferable with respect to a total of 100 weight part of all the resin components contained in the insulating sheet, More preferably, it is 30-50 weight part. It is a range. When there are too few polymers (A), the handleability of an insulating sheet may fall, and when there are too many, dispersion | distribution of a filler (D) may become difficult. The total resin component means the sum of the polymer (A), the epoxy monomer (B1), the oxetane monomer (B2), the curing agent (C), and other resin components added as necessary. .

(Epoxy monomer (B1) and oxetane monomer (B2))
The insulating sheet according to the present invention has an aromatic skeleton and an epoxy monomer (B1) having a weight average molecular weight of 600 or less, and / or an oxetane monomer having an aromatic skeleton and a weight average molecular weight of 600 or less ( B2). The insulating sheet may contain only one of the epoxy monomer (B1) and the oxetane monomer (B2), or may contain both.

  The epoxy monomer (B1) is not particularly limited. For example, an epoxy monomer having a bisphenol skeleton of bisphenol A type, bisphenol F type, or bisphenol S type; a phenol novolac epoxy having a dicyclopentadiene dioxide or dicyclopentadiene skeleton. Epoxy monomers having a dicyclopentadiene skeleton such as monomers; 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7- Epoxy monomers having a naphthalene skeleton such as diglycidylnaphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene; 1,3-bis (4 Epoxy monomers having an adamantene skeleton such as glycidyloxyphenyl) adamantene and 2,2-bis (4-glycidyloxyphenyl) adamanten; 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4- Glycidyloxy-3-methylphenyl) fluorene, 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-dic Rophenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) fluorene and other epoxy monomers having a fluorene skeleton, 4,4′-diglycidylbiphenyl, 4,4′-diglycidyl-3, Epoxy resins having a biphenyl skeleton such as 3 ′, 5,5′-tetramethylbiphenyl; 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxy) Naphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyl) Oxynaphthyl) methane, 1,8′-bi (3,5-glycidyloxynaphthyl) methane, 1,2′-bi (2,7-glycidyloxy) Epoxy having a bi (glycidyloxyphenyl) methane skeleton such as sinaphtyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,5-glycidyloxynaphthyl) methane Monomer; Epoxy monomer having xanthene skeleton such as 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene; having anthracene skeleton or pyrene skeleton An epoxy monomer etc. are mentioned. As for these epoxy monomers (B1), only 1 type may be used and 2 or more types may be used together.

  The oxetane monomer (B2) is not particularly limited, and examples thereof include 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, oxetated phenol novolac and the like. As for these oxetane monomers (B2), only 1 type may be used and 2 or more types may be used together.

  The epoxy monomer (B1) and / or oxetane monomer (B2) has a weight average molecular weight of 600 or less. The preferable lower limit of the weight average molecular weight of the epoxy monomer (B1) and / or the oxetane monomer (B2) is 200, and the preferable upper limit is 550. If the weight average molecular weight is too small, the volatility is too high and the handleability of the insulating sheet may be lowered. If it is too large, the sheet may be hard and brittle, or the adhesive force may be lowered.

  The total amount of the epoxy monomer (B1) and / or oxetane monomer (B2) is preferably in the range of 10 to 60 parts by weight with respect to a total of 100 parts by weight of all resin components contained in the insulating sheet. More preferably, it is the range of 10-40 weight part. When there are too few epoxy monomers (B1) and / or oxetane monomers (B2), adhesiveness and heat resistance may fall, and when too much, the softness | flexibility of an insulating sheet may fall.

(Curing agent (C))
The curing agent (C) contained in the insulating sheet according to the present invention is not particularly limited, but is a thermosetting curing agent such as a phenolic curing agent, an acid anhydride curing agent, an amine curing agent, or dicyandiamide. Examples include latent curing agents. Among them, a cured product of an insulating sheet having an excellent balance of heat resistance, moisture resistance, and electrical properties can be obtained. Therefore, a phenol resin, an acid anhydride, a water additive thereof, or a modified product thereof is preferable. An acid anhydride having an aliphatic skeleton or an alicyclic skeleton, a water additive thereof, or a modified product thereof is more preferable. A hardening | curing agent (C) may be used independently and 2 or more types may be used together.

  The phenol resin is not particularly limited, but is phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene modified novolak, decalin modified. Examples include novolak, poly (di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, poly (di-p-hydroxyphenyl) methane, and the like. Especially, since a sheet | seat softness | flexibility and a flame retardance are improved further, the phenol resin which has a melamine skeleton, the phenol resin which has a triazine skeleton, or the phenol resin which has an allyl group is preferable.

  Examples of commercially available phenol resins include MEH-8005, MEH-8010, NEH-8015 manufactured by Meiwa Kasei Co., Ltd .; YLH903 manufactured by Japan Epoxy Resin; LA-7052, LA-7054, LA- 7751, LA-1356, LA-3018-50P; PS6313 and PS6492 manufactured by Gunei Chemical Co., Ltd.

  Although it does not specifically limit as said acid anhydride, For example, acid anhydride type hardening | curing agents, such as methyl tetrahydro phthalic anhydride, methyl hexahydro phthalic anhydride, methyl nadic acid anhydride, trialkyl tetrahydro phthalic anhydride, are mentioned.

  Further, the acid anhydride having an aromatic skeleton, its water additive or its modified product is not particularly limited, and examples thereof include styrene / maleic anhydride copolymer, benzophenone tetracarboxylic acid anhydride, pyromellitic acid anhydride, Mellitic acid anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydrophthalic anhydride Methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride and the like. Of these, methylnadic acid anhydride and trialkyltetrahydrophthalic anhydride are preferable because water resistance is improved.

  Examples of commercially available acid anhydrides having an aromatic skeleton, water additives thereof, and modified products thereof include SMA Resin EF30, SMA Resin EF40, SMA Resin EF60, and SMA Resin EF80 manufactured by Sartomer Japan; manufactured by Manac ODPA-M, PEPA; Rikagit MTA-10, Rikagit MTA-15, Rikagit TMTA, Rikagit TMEG-100, Rikagit TMEG-200, Rikagit TMEG-300, Rikagit TMEG-500, Rikagit TMEG-S, manufactured by Shin Nippon Chemical Co., Ltd. Rikagit TH, Rikagit HT-1A, Rikagit HH, Rikagit MH-700, Rikagit MT-500, Rikagit DSDA, Rikagit TDA-100; EPICLON B4400, EPICLON B65 manufactured by Dainippon Ink & Chemicals, Inc. 0, EPICLON B570 and the like.

  Moreover, as an acid anhydride having an alicyclic skeleton, a water additive thereof, or a modified product thereof, an acid anhydride having a polyalicyclic skeleton, an alicyclic ring obtained by an addition reaction of a terpene compound and maleic anhydride An acid anhydride having a formula skeleton, a water additive thereof or a modified product thereof is preferred. In this case, the flexibility, moisture resistance, and / or adhesiveness of the insulating sheet can be further enhanced. Examples of the acid anhydride having an alicyclic skeleton, a water additive thereof, or a modified product thereof include methyl nadic acid anhydride, an acid anhydride having a dicyclopentadiene skeleton, or a modified product thereof.

  Examples of commercially available acid anhydrides having the alicyclic skeleton, water additives thereof, or modified products thereof include Rikajito HNA and Rikajito HNA-100 manufactured by Shin Nippon Rika Co., Ltd .; EpiCure YH306 and EpiCure YH307 manufactured by Japan Epoxy Resin Co., Ltd. Epicure YH308H, Epicure YH309, and the like.

  As the curing agent (C), the flexibility, moisture resistance, adhesion and the like of the sheet are further enhanced, so that an addition reaction between an acid anhydride having a polyalicyclic skeleton or a terpene compound and maleic anhydride is performed. An acid anhydride having an alicyclic skeleton obtained by the above, a water additive thereof, or a modified product thereof is preferred.

  Moreover, as the said hardening | curing agent (C), since the softness | flexibility of a sheet | seat, moisture resistance, adhesiveness, etc. are improved further, the acid anhydride represented by either of following formula (1)-(3) is more. preferable.

  In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.

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

  Although it does not specifically limit as said hardening accelerator, For example, diazabicycloalkenes, such as tertiary amine, imidazole, imidazoline, triazine, organophosphorus compound, quaternary phosphonium salt, organic acid salt; zinc octylate Organic metal compounds such as tin octylate and aluminum acetylacetone complex; quaternary ammonium salts; metal halides.

  Examples of the curing accelerator include high melting point imidazole compounds, dicyandiamide, or high melting point dispersion type latent accelerators such as amine addition type accelerators in which an amine is added to an epoxy monomer, imidazole-based, phosphorus-based or phosphine-based accelerators. Microcapsule-type latent accelerators coated with polymer, amine salt-type latent curing accelerators, high-temperature dissociation type thermal cationic polymerization type latent curing accelerators such as Lewis acid salts and Bronsted acid salts Representative latent curing accelerators can also be used. Especially, since it is easy to control the reaction system for adjusting a cure rate, the physical property of hardened | cured material, etc., a high melting point imidazole type hardening accelerator is used suitably. These curing accelerators may be used alone or in combination of two or more. Since the handleability is excellent, the curing accelerator preferably has a melting point of 100 ° C. or higher.

(Filler (D))
The insulating sheet according to the present invention includes a filler (D), and the filler (D) includes a spherical filler (D1) having an average particle diameter of 0.1 to 0.5 μm and a spherical filler having an average particle diameter of 2 to 6 μm. (D2) and a spherical filler (D3) having an average particle diameter of 10 to 40 μm are included. In 100% by volume of the filler (D), 5 to 30% by volume of the spherical filler (D1), 20 to 60% by volume of the spherical filler (D2), and 20 to 60% by volume of the spherical filler (D3). , Spherical fillers (D1), (D2) and (D3) are included in amounts not exceeding 100% by volume.

  That is, in the present invention, in the composition containing the above components (A) to (D), a small particle size spherical filler (D1), a medium particle size spherical filler (D2), and a large particle size spherical filler (D3). ) In combination with the above specific ratio, the cured product of the insulating sheet has high thermal conductivity and is excellent in adhesiveness and dielectric breakdown characteristics.

  When the average particle diameter of the spherical filler (D1) is less than 0.1 μm, filling may be difficult or adhesiveness may be lowered.

  When the average particle size of the spherical filler (D1) exceeds 0.5 μm, or the average particle size of the spherical filler (D2) is less than 2 μm, the particle size of the spherical filler (D1) and the spherical filler (D2) Is too close, it is difficult to form a densely packed structure, and sufficient filling properties may not be ensured. Therefore, in the cured product of the insulating sheet, the thermal conductivity may be lowered, or local filler agglomeration may occur and the adhesiveness may be lowered, or the insulating property may not be sufficiently obtained.

  When the average particle diameter of the spherical filler (D2) exceeds 6 μm or the average particle diameter of the filler (D3) is less than 10 μm, the particle diameters of the spherical filler (D2) and the spherical filler (D3) are close to each other. Therefore, sufficient fillability may not be ensured. Therefore, in the cured product of the insulating sheet, the thermal conductivity may be lowered, the filler may be aggregated, the insulating property may be lowered, and the adhesive force may not be sufficiently obtained.

  When the average particle diameter of the spherical filler (D3) exceeds 40 μm, the insulating property may be remarkably lowered when the thickness of the insulating sheet is reduced to about 100 μm.

  In addition, in this specification, an average particle diameter is an average particle diameter calculated | required from the particle size distribution measurement result in the volume average measured with the laser diffraction type particle size distribution measuring apparatus.

  If the filler (D) does not contain the spherical fillers (D1), (D2), and (D3) at the volume ratios, sufficient filling properties may not be ensured. For this reason, thermal conductivity may be lowered, filler aggregation may occur, insulation may be reduced, and sufficient adhesive strength may not be obtained.

  The spherical fillers (D1), (D2), and (D3) have a spherical shape. A spherical shape means an aspect ratio in the range of 1-2.

  The insulating sheet of this invention should just contain the spherical filler (D1), (D2), and (D3) of the said specific particle size in the said specific ratio, respectively. Further, the filler (D) may have a particle size different from the spherical fillers (D1), (D2), and (D3), or may contain a non-spherical filler (hereinafter referred to as filler (D4)). Good. The insulating sheet preferably does not contain the filler (D4), but when it contains the filler (D4), the content is preferably 5% by volume or less in 100% by volume of the filler (D). .

  As the particle size distribution of the spherical filler (D1), the maximum particle size is preferably 2 μm or less, and the minimum particle size is preferably 0.01 μm or more. As the particle size distribution of the spherical filler (D2), the maximum particle size is preferably 40 μm or less, and the minimum particle size is preferably 0.1 μm or more. As the particle size distribution of the spherical filler (D3), the maximum particle size is preferably 60 μm or less, and the minimum particle size is preferably 0.5 μm or more.

  In the present invention, when the particle size distribution of all the fillers (D) contained in the insulating sheet is measured, when the cumulative volume of the filler (D) is measured from the smallest particle size, the particle size is 0.1 μm. The cumulative volume is preferably in the range of 0 to 5%, the cumulative volume% in the particle size of 0.5 μm is preferably in the range of 1 to 10%, and the cumulative volume% in the particle size of 2 μm is 2 to 20%. The cumulative volume% at a particle size of 6 μm is preferably in the range of 20 to 50%, the cumulative volume% at a particle size of 10 μm is preferably in the range of 30 to 80%, and the particle size of 40 μm. The cumulative volume% in is preferably in the range of 80 to 100%.

  In the present specification, the particle size distribution means a value in the case of a particle size distribution with a volume average measured by a laser diffraction particle size distribution measuring device.

  Although it does not specifically limit as said filler (D), Since thermal conductivity is raised further, at least 1 selected from the group which consists of alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, zinc oxide, and magnesium oxide. Species are preferred. When a dispersant having a low pKa, that is, a high acidity is used as the dispersant (F) described later, dissolution in the dispersant can be prevented, so alumina, aluminum nitride, boron nitride, silicon carbide, and silicon nitride More preferred is at least one selected from the group consisting of Moreover, since heat dissipation is further improved, spherical alumina and / or spherical aluminum nitride is more preferable. Furthermore, since the dispersion | distribution dispersion | variation resulting from the difference in specific gravity etc. is hard to generate | occur | produce, it is preferable that the main components of the said spherical filler (D1), (D2), and (D3) are the same.

  As a compounding quantity of the said filler (D), the range of 65-90 volume% is preferable in 100 volume% of insulating sheets. If it is less than 65 volume%, the heat dissipation may not be sufficiently improved, and if it exceeds 90 volume%, the flexibility and adhesiveness of the insulating sheet may be significantly reduced.

(Dispersant (F))
The insulating sheet according to the present invention preferably further contains a dispersant (F) having a functional group containing a hydrogen atom having hydrogen bonding properties. When an insulating sheet contains the said dispersing agent (F), the thermal conductivity and dielectric breakdown characteristic of the hardened | cured material of an insulating sheet can be improved further.

  Examples of the functional group containing a hydrogen atom having hydrogen bonding include a carboxyl group (pKa = 4), a phosphate group (pKa = 7), a phenol group (pKa = 10), and the like.

  The pKa of the functional group containing a hydrogen atom having hydrogen bonding properties is preferably in the range of 2 to 10, more preferably in the range of 3 to 9. When the pKa is less than 2, since the acidity of the dispersant is too high, the reaction of the epoxy component and / or the oxetane component in the raw resin component is easily promoted, and when the uncured insulating sheet is stored, Its storage stability may be inferior. When pKa exceeds 10, the function as a dispersant may not be sufficiently achieved, and the thermal conductivity and dielectric breakdown characteristics of the cured product of the insulating sheet may not be sufficiently improved.

  Since the thermal conductivity and dielectric breakdown characteristics of the cured product of the insulating sheet can be further enhanced, the functional group containing a hydrogen atom having hydrogen bonding properties is preferably a carboxyl group or a phosphate group.

  Specific examples of the dispersant (F) include polyester carboxylic acid, polyether carboxylic acid, polyacrylic carboxylic acid, aliphatic carboxylic acid, polysiloxane carboxylic acid, polyester phosphoric acid, Polyether phosphoric acid, polyacrylic phosphoric acid, aliphatic phosphoric acid, polysiloxane phosphoric acid, polyester phenol, polyether phenol, polyacrylic phenol, aliphatic phenol, polysiloxane phenol, etc. Can be mentioned. A dispersing agent (F) may be used independently and may use 2 or more types together.

  As a compounding ratio of the said dispersing agent (F), the range of 0.01-20 weight part is preferable in 100 weight part of insulating sheets, More preferably, it is the range of 0.1-10 weight part. When the blending ratio of the dispersant (F) is within this range, aggregation of the filler (D) can be suppressed, and the thermal conductivity and dielectric breakdown characteristics of the cured product of the insulating sheet can be sufficiently enhanced.

(Rubber particles (E))
The insulating sheet according to the present invention may contain rubber fine particles (E).

  The rubber particles (E) are not particularly limited. For example, acrylic rubber, butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, styrene isoprene rubber, urethane rubber, silicone rubber, fluorine rubber, natural rubber, etc. Can be used regardless. Of these, silicone rubber is preferable because stress relaxation and flexibility of the insulating sheet after curing are enhanced.

  By using the rubber particles (E) and the filler (D) in combination, the insulating sheet has a low coefficient of linear thermal expansion and a stress relaxation capability, such as peeling and cracking under high temperature and cooling cycle conditions. Generation | occurrence | production can be suppressed further.

  The blending ratio of the rubber particles (E) is preferably in the range of 0.1 to 40 parts by weight, more preferably in the range of 0.3 to 20 parts by weight, in 100 parts by weight of the insulating sheet. When there are too few rubber particles (E), the stress relaxation property of hardened | cured material may not fully express, and when too large, adhesiveness may become low.

(Other ingredients)
The insulating sheet according to the present invention may contain a base material such as glass cloth, glass nonwoven fabric, and aramid nonwoven fabric in order to further enhance sheet characteristics. However, even if these base materials are not included, the insulating sheet of the present invention can be self-supporting even in an uncured state at room temperature (23 ° C.) and can have excellent sheet characteristics. Therefore, the insulating sheet preferably does not contain a base material, and particularly preferably does not contain glass cloth. When the base material is not included, the insulating sheet can be made thin, and the thermal conductivity of the insulating sheet can be further increased. Further, various types of laser processing, drilling, etc. are performed on the insulating sheet as necessary. Processing can also be performed easily. In addition, self-supporting means that the shape of the sheet can be maintained and handled as a sheet even in the absence of a support such as a PET film or copper foil, even in an uncured state. And

  Moreover, the insulating sheet of the present invention may contain a thixotropic agent, a dispersant, a flame retardant, a colorant, and the like as necessary.

(Insulating sheet)
The insulating sheet according to the present invention is not particularly limited, but can be obtained, for example, by molding a mixture of 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.

  Although it does not specifically limit as a film thickness of an insulating sheet, The range of 10-300 micrometers is preferable. More preferably, it is the range of 50-200 micrometers, Most preferably, it is 70-120 micrometers. If the film thickness is too thin, the insulating property may be lowered, and if it is too thick, the heat dissipation may be lowered when the metal body is bonded to the conductive layer.

  The insulating sheet according to the present invention can obtain extremely high dielectric breakdown characteristics particularly when the film thickness is thick. However, even if the film thickness is small, the insulating sheet has sufficient dielectric breakdown characteristics.

  Moreover, it is preferable that the glass transition temperature Tg in the uncured state of the insulating sheet which concerns on this invention is 25 degrees C or less. When the glass transition temperature exceeds 25 ° C., it may be hard and brittle at room temperature, and the handling properties of the insulating sheet may be lowered.

  The thermal conductivity after curing of the insulating sheet is preferably 3.0 W / m · K or more. More preferably, it is 5.0 W / m · K or more, and still more preferably 7.0 W / m · K or more. If the thermal conductivity is too low, sufficient heat dissipation may not be obtained.

  The dielectric breakdown voltage after curing of the insulating sheet is preferably 30 kV / mm or more. More preferably, it is 40 kV / mm or more, More preferably, it is 50 kV / mm or more, More preferably, it is 80 kV / mm or more, More preferably, it is 100 kV / mm or more. If the dielectric breakdown voltage is too low, sufficient insulation may not be obtained when used for high current applications such as for power devices.

The volume resistivity after curing of the insulating sheet is preferably 10 ¹⁴ Ω · cm or more. More preferably, it is 10 ¹⁶ Ω · cm or more. If the volume resistivity is too low, insulation between the conductor layer and the high thermal conductor may not be maintained.

  The coefficient of thermal expansion after curing of the insulating sheet is preferably 30 ppm / ° C. or less. More preferably, it is 20 ppm / ° C. or less. If the coefficient of thermal expansion is too high, the thermal cycle resistance may be inferior.

(Laminated structure)
The insulating sheet according to the present invention is used to bond a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer. The insulating sheet 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 high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer. It is used suitably for. For example, by bonding a metal body via an insulating sheet to each conductive layer such as a laminated board with a double-sided copper circuit or a multilayer wiring board, copper foil, copper plate, semiconductor element, semiconductor package, etc., by curing the insulating sheet, The laminated structure can be obtained.

  In FIG. 1, the laminated structure which concerns on one Embodiment of this invention is typically shown with a partial notch front sectional drawing.

  In the laminated structure 1 shown in FIG. 1, a high thermal conductor 4 is laminated on a surface 2 a of a conductive layer 2 as a heat source via an insulating layer 3. The insulating layer 3 is formed by curing the insulating sheet of the present invention. As the high thermal conductor 4, a high thermal conductor having a thermal conductivity of 10 W / m · K or more is used.

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

  The high thermal conductor 4 having a thermal conductivity of 10 W / m · K or more is not particularly limited, and examples thereof include aluminum, copper, alumina, beryllia, silicon carbide, silicon nitride, aluminum nitride, and a graphite sheet. Especially, since it is excellent in heat dissipation, copper and aluminum are preferable.

  The insulating sheet according to the present invention is suitably used for bonding a high thermal 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 sheet according to the present invention adheres a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer of an electronic component device in which electronic component elements other than semiconductor elements are mounted on a substrate. Are also preferably used.

  In the case where the semiconductor element is a power device element for a large current, a higher insulation property or a higher heat resistance is required. Therefore, in such an application, the insulating sheet of the present invention is more preferably used.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. In addition, this invention is not limited to a following example.

  The following materials were prepared.

[Polymer (A)]
(1) Bisphenol A-type phenoxy resin (trade name: E1256, Mw = 51,000, Tg = 98 ° C., manufactured by Japan Epoxy Resin Co., Ltd.)
(2) High heat resistance phenoxy resin (manufactured by Toto Kasei Co., Ltd., trade name: FX-293, Mw = 43,700, Tg = 163 ° C.)
(3) Epoxy group-containing styrene resin (manufactured by NOF Corporation, trade name: Marproof G-1010S, Mw = 100,000, Tg = 93 ° C.)

[Polymers other than polymer (A)]
(1) Epoxy group-containing acrylic resin (manufactured by NOF Corporation, trade name: Marproof G-0130S, Mw = 9,000, Tg = 69 ° C.)

[Epoxy monomer (B1)]
(1) Bisphenol A type liquid epoxy resin (made by Japan Epoxy Resin, trade name: Epicoat 828US, Mw = 370)
(2) Bisphenol F type liquid epoxy resin (made by Japan Epoxy Resin, trade name: Epicoat 806L, Mw = 370)
(3) Trifunctional glycidyldiamine type liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., 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 (Dainippon Ink Chemical Co., Ltd., trade name: EPICLON HP-4032D, Mw = 304)

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

[Monomers other than epoxy monomer (B1) and oxetane monomer (B2)]
(1) Hexahydrophthalic acid skeleton liquid epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: AK-601, Mw = 284)
(2) Bisphenol A type solid epoxy resin (product name: 1003, Mw = 1300, manufactured by Japan Epoxy Resin Co., Ltd.)

[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 (manufactured by Japan Epoxy Resin, trade name: Epicure YH-306)
(5) Biphenyl skeleton phenolic resin (Madewa Kasei Co., Ltd., trade name: MEH-7851-S)
(6) Allyl group-containing skeletal phenol resin (manufactured by Japan Epoxy Resin, trade name: YLH-903)
(7) Triazine skeleton phenolic resin (Dainippon Ink Chemical Co., Ltd., trade name: Phenolite KA-7052-L2)
(8) Melamine skeleton phenolic resin (manufactured by Gunei Chemical Industry Co., Ltd., trade name: PS-6492)
(9) Isocyanur-modified solid dispersion type imidazole (imidazole curing accelerator, manufactured by Shikoku Kasei Co., Ltd., trade name: 2MZA-PW)

[Filler (D)]
Spherical filler (D1)
(1) Spherical alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name: AKP-30, average particle size 0.4 μm, aspect ratio 1.1 to 2.0, thermal conductivity 36 W / m · K)
(2) Spherical magnesium oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: SMO Small Particle, average particle size 0.1 μm, aspect ratio 1.1 to 1.5, thermal conductivity 42 W / m · K)

Spherical filler (D2)
(1) Spherical alumina (Denka Co., Ltd., trade name: DAM-05, average particle size 5 μm, aspect ratio 1 to 1.2, thermal conductivity 36 W / m · K)
(2) Spherical aluminum nitride (manufactured by Toyo Aluminum Co., Ltd., trade name: TOYALNITE-FLC, average particle size 3.7 μm, aspect ratio 1-1.3, thermal conductivity 200 W / m · K)

Spherical filler (D3)
(1) Spherical alumina (manufactured by Admatechs, trade name: AO-820, average particle size 20 μm, aspect ratio 1 to 1.1, thermal conductivity 36 W / m · K)
(2) Spherical aluminum nitride (manufactured by Toyo Aluminum Co., Ltd., trade name: TOYALNITE-FLD, average particle size 30 μm, aspect ratio 1-1.3, thermal conductivity 200 W / m · K)

[Other fillers (D4) other than spherical fillers (D1), (D2) and (D3)]
(1) Spherical alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name: AA-07, average particle size 0.7 μm, aspect ratio 1.1-2.0, thermal conductivity 36 W / m · K)

[Dispersant (F)]
(1) Acrylic dispersant (manufactured by Big Chemie Japan, trade name: Disperbyk-2070, pKa has a carboxyl group of 4)
(2) Polyether-based dispersant (manufactured by Enomoto Kasei Co., Ltd., trade name: ED151, pKa has 7 phosphate groups)

[Dispersants other than dispersant (F)]
(1) Nonionic dispersant (manufactured by Kyoeisha Chemical Co., Ltd., trade name: D-90, a dispersant having no functional group containing hydrogen atoms having hydrogen bonding properties)

[Rubber particles (E)]
(1) Core shell type rubber fine particles (manufactured by Mitsubishi Rayon Co., Ltd., trade name: KW4426, rubber fine particles having a shell made of methyl methacrylate and a core made of butyl acrylate, an average particle size of 5 μm)
(2) Silicone rubber fine particles (manufactured by Dow Corning Toray, trade name: Trefil E601, average particle size 2 μm)

[Additive]
(1) Epoxysilane coupling agent (Shin-Etsu Chemical Co., Ltd., trade name: KBE403)

[solvent]
(1) Methyl ethyl ketone

Example 1
Using a homodisper type stirrer, each compound was blended and kneaded at the ratio shown in Table 1 below to prepare an insulating material.

  The insulating material was applied to a 50 μm-released PET sheet to 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.

(Examples 2 to 23 and Comparative Examples 1 to 5)
An insulating material was prepared in the same manner as in Example 1 except that the types and blending amounts of the components used were as shown in Tables 1 and 2 below, and an insulating sheet was produced on the PET sheet.

(Examples 24-26)
An insulating material was prepared in the same manner as in Example 1 except that the types and blending amounts of the components used were as shown in Table 2 below, and an insulating sheet was produced on the PET sheet.

(Evaluation of Examples and Comparative Examples)
The following items were evaluated for each insulating sheet obtained as described above.

(1. Handling property)
A test sample was prepared by cutting a PET sheet and an insulating sheet formed on the PET sheet into a 460 mm × 610 mm square. In this test sample, the handling property when the uncured insulating sheet was peeled from the PET sheet at room temperature (23 ° C.) was evaluated according to the following 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. ×: The insulating sheet cannot be peeled.

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

(3. Thermal conductivity)
The insulating sheet was cured by heating in an oven at 120 ° C. for 1 hour and then at 200 ° C. for 1 hour. The heat conductivity of the hardened | cured material of the insulating sheet was measured using the Kyoto Denshi Kogyo company thermal conductivity meter "rapid thermal conductivity meter QTM-500".

(4. Peeling strength)
An insulating sheet is sandwiched between an aluminum plate having a thickness of 1 mm and an electrolytic copper foil having a thickness of 35 μm, and the insulating sheet is press-cured at 120 ° C. for 1 hour and further at 200 ° C. for 1 hour while maintaining a pressure of 4 MPa with a vacuum press machine. A copper-clad laminate of the base substrate was formed. The copper foil of the obtained metal base substrate is etched to form a 10 mm wide copper foil strip, and the peel strength when the copper foil is peeled from the substrate at an angle of 90 ° C. and a pulling speed of 50 mm / min. Was measured.

(5. Dielectric breakdown voltage)
An insulating sheet cut into 100 mm × 100 mm square was cured in a 120 ° C. oven for 1 hour and further in a 200 ° C. oven for 1 hour to prepare a test sample. Using a withstand voltage tester (MODEL7473, manufactured by EXTECH Electronics), the voltage was increased at a rate of 1 kV / sec, and the dielectric breakdown voltage of the test sample was measured.

(6. Solder heat resistance)
The copper-clad laminate prepared by the above (4) evaluation of the peel strength was cut out to a size of 50 mm × 60 mm. This 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.

◎: No swelling or peeling even after 10 minutes ◯: Swelling after 3 minutes and before 10 minutes passed, peeling occurred △: Swelled after 1 minute and before 3 minutes passed, Peeling occurred ×: Swelled and peeled before 1 minute passed

(7. Particle size distribution of filler)
The particle size distribution of all fillers (D) contained in the insulating sheet was measured using a laser diffraction particle size distribution measuring device. Based on the measurement results, the cumulative volume of filler (D) is calculated from the small particle size, so that the cumulative volume% at the particle size of 0.1 μm, 0.5 μm, 2.0 μm, 6.0 μm and 10.0 μm. Got.

  The results are shown in Table 1 below.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated structure 2 ... Conductive layer 2a ... Surface 3 ... Insulating layer 4 ... High thermal conductor

Claims (12)

An insulating sheet used to adhere a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer,
A polymer (A) having an aromatic skeleton and having a weight average molecular weight of 30,000 or more;
An epoxy monomer (B1) having an aromatic skeleton and having a weight average molecular weight of 600 or less and / or an oxetane monomer (B2) having an aromatic skeleton and having a weight average molecular weight of 600 or less;
A curing agent (C);
Containing filler (D),
The polymer (A) is a thermosetting resin,
In 100% by volume of the filler (D), 5 to 30% by volume of spherical filler (D1) having an average particle size of 0.1 to 0.5 μm and 20 to 60 volumes of spherical filler (D2) having an average particle size of 2 to 6 μm. % And spherical filler (D3) 20-60% by volume with an average particle size of 10-40 μm are included in amounts that the total of spherical fillers (D1), (D2) and (D3) does not exceed 100% by volume. and,
Per 100 parts by weight of the total resin components contained in the insulating sheet, the content of the polymer (A) is characterized in der Rukoto the range of 30 to 60 parts by weight, the insulating sheet.   The insulating sheet according to claim 1, further comprising a dispersant (F) having a functional group containing a hydrogen atom having hydrogen bonding properties.   The insulating sheet according to claim 2, wherein pKa of the functional group of the dispersant (F) is in the range of 2 to 10.   The filler (D) according to any one of claims 1 to 3, wherein the filler (D) is at least one selected from the group consisting of alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, zinc oxide, and magnesium oxide. The insulating sheet described.   The insulating sheet according to any one of claims 1 to 4, wherein main components of the spherical fillers (D1), (D2), and (D3) are the same.   The insulating sheet according to any one of claims 1 to 5, wherein the polymer (A) is a phenoxy resin.   The insulating sheet according to claim 6 whose glass transition temperature Tg of said phenoxy resin is 95 ° C or more.   The curing agent (C) is an acid anhydride having a polyalicyclic skeleton, an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive thereof, or The insulating sheet according to any one of claims 1 to 7, which is a modified product thereof. The insulating sheet according to claim 8, wherein the curing agent (C) is an acid anhydride represented by any of the following formulas (1) to (3).

In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.   The insulating sheet according to any one of claims 1 to 7, wherein the curing agent (C) is a phenol resin having a melamine skeleton or a triazine skeleton, or a phenol resin having an allyl group.   The conductive layer is laminated | stacked through the insulating layer on the at least single side | surface of the high heat conductor whose heat conductivity is 10 W / m * K or more, This insulating layer is any one of Claims 1-10. A laminated structure formed by curing an insulating sheet.   The laminated structure according to claim 11, wherein the high thermal conductor is a metal.

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