JP2009224109A - Insulation sheet and laminated structural body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation sheet bringing forth a cured object excellent in handleability at an uncured state, and yet, excellent in dielectric breakdown characteristics, thermal conductivity, and adhesion. <P>SOLUTION: The insulation sheet 3 contains a thermoplastic elastomer (A) as a block copolymer having at least two hard segments and at least one soft segment, used for bonding a high thermal conductor 4 with a thermal conductivity of 10 W/m×K or more to a conductive layer 2, with a weight-average molecular weight of 30,000 or more, an epoxy monomer (B1) and/or an oxetane monomer (B2) having an aromatic skeleton with a weight-average molecular weight of 600 or less, a curing agent (C) that is phenol resin or acid anhydride having an aromatic skeleton or alicyclic skeleton, its hydrogenated matter or degenerated matter, and a filler (D) with a thermal conductivity of 30 W/m×K or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to 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, and more specifically, has excellent handling properties in an uncured state, and The present invention relates to an insulating sheet that gives a cured product excellent in dielectric breakdown characteristics, thermal conductivity, and adhesiveness, 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. 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. This insulating adhesive material is strongly required to have a 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.

On the other hand, insulating adhesive materials that do not use 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 novolac, 1-cyanoethyl-2-phenylimidazole, γ-glycidoxypropyltrimethoxysilane, and alumina. Agents are disclosed. Here, tertiary amines, acid anhydrides, imidazole compounds, polyphenol resins, mask isocyanates and the like are listed as curing agents for epoxy resins.
JP 2006-342238 A JP-A-8-332696

  However, in the insulating adhesive sheet described in Patent Document 1, a glass cloth is used in order to improve handling properties. When glass cloth is used, it is difficult to make a thin film, and it is difficult to perform various processes such as laser processing and drilling. Furthermore, since the cured product of the insulating adhesive sheet containing glass cloth has a relatively low thermal conductivity, sufficient heat dissipation may not be obtained. Furthermore, special impregnation equipment had to be prepared in order to impregnate the glass cloth with the adhesive composition.

  On the other hand, since the insulating adhesive of Patent Document 2 does not use a glass cloth, the above-described various problems associated with the use of the glass cloth do not occur. However, this insulating adhesive is not a sheet that is self-supporting in an uncured state, and therefore handling properties are not sufficient.

  The object of the present invention is used in order 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 above-described state of the prior art, and even if a glass cloth is not used, An object of the present invention is to provide an insulating sheet that provides a cured product that is excellent in handling properties in an uncured state and that has excellent dielectric breakdown characteristics, thermal conductivity, and adhesiveness, and a laminated structure using the insulating sheet.

  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, which has at least two hard segments and at least one soft segment. A block copolymer and a thermoplastic elastomer (A) having a weight average molecular weight of 30,000 or more, an epoxy monomer (B1) having an aromatic skeleton and a weight 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 phenol resin, an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof, or a modified product thereof A curing agent (C) and a filler (D) having a thermal conductivity of 30 W / m · K or more, the thermoplastic elastomer (A), and the epoxy The thermoplastic elastomer (A) is 20 to 60% by weight in a total of 100% by weight of the resin component in the insulating sheet containing the monomer (B1) and / or the oxetane monomer (B2) and the curing agent (C). %, The epoxy monomer (B1) and / or the oxetane monomer (B2) is 10 to 60% by weight, and the thermoplastic elastomer (A), the epoxy monomer (B1) and / or the oxetane monomer. An insulating sheet is provided, characterized in that the total content of (B2) is less than 100% by weight.

  In a specific aspect of the insulating sheet of the present invention, the hard segment is made of at least one selected from the group consisting of styrene, aromatic urethane, alicyclic urethane, amide, and imide, and the soft segment is , A olefin hydrocarbon having 2 to 5 carbon atoms having no conjugated diene, a conjugated diene compound having 4 to 6 carbon atoms, a hydrocarbon compound containing a partially hydrogenated conjugated diene having 4 to 6 carbon atoms as a structural unit, and silicone It consists of at least one selected from In this case, the handling property of the insulating sheet in an uncured state can be further enhanced.

  In another specific aspect of the insulating sheet of the present invention, the weight ratio of the hard segment to the soft segment (hard segment: soft segment) in the block copolymer is in the range of 10:90 to 50:50. In this case, the handling property of the insulating sheet in an uncured state can be further enhanced.

  In still another specific aspect of the insulating sheet of the present invention, the hard segment has an epoxy group, an oxetanyl group, a (meth) acryloyl group, an amino group, a carboxyl group, or a hydroxyl group. In this case, the heat resistance of the insulating sheet can be further increased.

  Further, as the curing agent (C), an acid anhydride having a polyalicyclic skeleton, an acid anhydride having an alicyclic skeleton obtained by an addition reaction between a terpene compound and maleic anhydride, its water Additives or modified products thereof are also preferable, and acid anhydrides represented by any of the following formulas (1) to (3) are more preferable. In these cases, the flexibility, moisture resistance and / or adhesion of the insulating sheet can be further enhanced.

上記式（３）中、Ｒ１及びＲ２はそれぞれ独立に、水素、炭素数１〜５のアルキル基、又は水酸基を示す。

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, the sheet flexibility and flame retardancy 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, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. Seeds are preferred, and spherical alumina and / or spherical aluminum nitride are more preferred. When these fillers (D) are used, the heat dissipation 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. 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.

  In the insulating sheet according to the present invention, the thermoplastic elastomer (A), which is a block copolymer having at least two hard segments and at least one soft segment, and has a weight average molecular weight of 30,000 or more is the component ( Since it is used in combination with B) to (D), the handleability of the insulating sheet in the uncured state can be improved. Furthermore, by curing the insulating sheet of the present invention, a cured product having excellent dielectric breakdown characteristics, thermal conductivity, and adhesiveness can be obtained.

  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. Furthermore, in the laminated structure, it is possible to suppress the occurrence of dielectric breakdown or peeling at the adhesion interface.

  Details of the present invention will be described below.

  The insulating sheet according to the present invention is a block copolymer having at least two hard segments and at least one soft segment, and has a weight average molecular weight of 30,000 or more, a thermoplastic elastomer (A), and an aromatic An epoxy monomer (B1) having a skeleton and a weight 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 phenol resin, or an aromatic A curing agent (C) which is an acid anhydride having an aliphatic skeleton or an alicyclic skeleton, a water additive or a modified product thereof, and a filler (D) having a thermal conductivity of 30 W / m · K or more. .

  As a result of intensive studies to solve the above problems, the inventors of the present application are block copolymers having at least two hard segments and at least one soft segment, and have a weight average molecular weight of 30,000 or more. Adopting a composition in which the thermoplastic elastomer (A) is combined with the epoxy monomer (B1) and / or the oxetane monomer (B2), the curing agent (C) and the filler (D), and in this specific composition By using the thermoplastic elastomer (A) and the epoxy monomer (B1) and / or the oxetane monomer (B2) in the specific ratio, the handling property in an uncured state is excellent, and further the insulation Found that an insulating sheet giving a cured product excellent in destructive properties, thermal conductivity and adhesiveness can be obtained, Leading to the completion of the invention.

(Thermoplastic elastomer (A))
The thermoplastic elastomer (A) contained in the insulating sheet according to the present invention is a block copolymer having at least two hard segments and at least one soft segment. A thermoplastic elastomer (A) may be used independently and 2 or more types may be used together.

  The structure of the block copolymer is not particularly limited, and when the hard segment is A and the soft segment is B, for example, an ABA structure, an ABBA structure, or the like. Examples thereof include a block copolymer in which hard segments are bonded to both ends of the soft segment.

  Although the hard segment in the said block copolymer is not specifically limited, For example, it consists of styrene, aromatic urethane, alicyclic urethane, amide, imide, etc. The hard segment may be polystyrene, aromatic polyurethane, alicyclic polyurethane, polyamide, polyimide, or the like.

  The hard segment in the block copolymer preferably has an epoxy group, oxetanyl group, (meth) acryloyl group, amino group, carboxyl group or hydroxyl group. When the hard segment has these groups, the thermoplastic elastomer (A) can be reacted with the epoxy monomer (B1) and / or the oxetane monomer (B2). Therefore, the heat resistance of the cured product can be further improved.

  Although the soft segment in the said block copolymer is not specifically limited, For example, C2-C5 olefin hydrocarbon which does not have a conjugated diene, C4-C6 conjugated diene compound, C4-C6 partial water It consists of a hydrocarbon compound, silicone and the like containing a conjugated diene as a structural unit.

  Examples of the olefin hydrocarbon having 2 to 5 carbon atoms not having the conjugated diene include ethylene, propylene, 2-methylpropene (isobutylene), 1-butylene, 2-butylene, 2-methyl-2-butylene, 1- Examples include pentene, 2-pentene, or 1,4-pentadiene.

  Examples of the conjugated diene compound having 4 to 6 carbon atoms include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, and the like.

  The block copolymer includes at least one selected from the group consisting of styrene, aromatic urethane, alicyclic urethane, amide, and imide, and the soft segment includes a conjugated diene. Selected from the group consisting of a hydrocarbon compound having 2 to 5 carbon atoms, a conjugated diene compound having 4 to 6 carbon atoms, a partially hydrogenated conjugated diene having 4 to 6 carbon atoms as a structural unit, and silicone It is preferable to consist of at least one. In this case, the handling property in the uncured state of the insulating sheet can be further enhanced.

  The block copolymer includes a block copolymer having two hard segments made of styrene and one soft segment made of 2-methylpropene, two hard segments made of styrene, ethylene and 1,3-butadiene. A block copolymer having two soft segments or a block copolymer having two hard segments made of aromatic urethane or alicyclic urethane and one soft segment made of silicone is more preferable. When the thermoplastic elastomer is such a block copolymer, the handleability of the insulating sheet in the uncured state can be further enhanced.

  The weight ratio of the hard segment to the soft segment (hard segment: soft segment) in the block copolymer is preferably in the range of 10:90 to 50:50. More preferably, it is the range of 20: 80-40: 60. In this case, the handling property of the insulating sheet in an uncured state can be further enhanced. If the ratio of the hard segment to the soft segment becomes too high, the cured product of the insulating sheet may become hard and brittle. If the ratio of the hard segment to the soft segment becomes too low, the strength of the cured product of the insulating sheet is insufficient. May be.

  The thermoplastic elastomer (A) has a weight average molecular weight of 30,000 or more. The weight average molecular weight of the thermoplastic elastomer (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, and if it is too large, the compatibility with other resin components 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. May decrease.

  100% by weight in total of all resin components contained in the insulating sheet containing the thermoplastic elastomer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), and the curing agent (C). In the thermoplastic elastomer (A), the proportion of the thermoplastic elastomer (A) is 20 to 60% by weight, preferably 30 to 50% by weight, and the thermoplastic elastomer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2). ) And a total amount of less than 100% by weight. When there are too few thermoplastic elastomers (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 thermoplastic elastomer (A), epoxy monomer (B1), oxetane monomer (B2), curing agent (C) and other resin components added as necessary. And

(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 novolak having a dicyclopentadiene dioxide or dicyclopentadiene skeleton. Epoxy monomers having a dicyclopentadiene skeleton such as epoxy 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 ( -Epoxy monomer having an adamantene skeleton such as glycidyloxyphenyl) adamantene and 2,2-bis (4-glycidyloxyphenyl) adamantene; 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-di (Lolophenyl) 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-glycidylo) Epoxy having a bi (glycidyloxyphenyl) methane skeleton such as xylnaphthyl) 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. For example, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, bis-1,4-benzenedicarboxylate [(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.

  When the epoxy monomer (B1) and the oxetane monomer (B2) are used in combination or when any one of them is used, the thermoplastic elastomer (A), the epoxy monomer (B1) and / or the oxetane are used. The epoxy monomer (B1) and / or oxetane monomer (B2) is 10 to 60 in a total of 100% by weight of all resin components contained in the insulating sheet containing the monomer (B2) and the curing agent (C). % By weight, preferably 10 to 40% by weight, and a ratio in which the total of the thermoplastic elastomer (A) and the epoxy monomer (B1) and / or oxetane monomer (B2) is less than 100% by weight. included.

  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 a phenol resin, an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof, or a modified product thereof. By using this hardening | curing agent (C), the hardened | cured material of the insulating sheet excellent in heat resistance, moisture resistance, and the balance of an electrical property can be obtained. 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 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, and poly (di-p-hydroxyphenyl) methane. 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.

  An acid anhydride having an aromatic skeleton, a water additive thereof, or a modified product thereof is not particularly limited. For example, styrene / maleic anhydride copolymer, benzophenone tetracarboxylic acid anhydride, pyromellitic acid anhydride, trimellitic acid Anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydrophthalic anhydride, methyl Examples include hexahydrophthalic anhydride and trialkyltetrahydrophthalic anhydride. 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.

  Moreover, since the softness | flexibility of a sheet | seat, moisture resistance, and / or adhesiveness can be improved further as said hardening | curing agent (C), the acid anhydride represented by either of following formula (1)-(3). More preferred.

上記式（３）中、Ｒ１及びＲ２はそれぞれ独立に、水素、炭素数１〜５のアルキル基、又は水酸基を示す。

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.

  The curing accelerator is not particularly limited. For example, diazabicycloalkenes such as tertiary amines, imidazoles, imidazolines, triazines, organic phosphorus compounds, quaternary phosphonium salts, and organic acid salts; octylic acid Organometallic compounds such as zinc, 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 hardening accelerators may be used independently and 2 or more types may be used together. Since the handleability is excellent, the curing accelerator preferably has a melting point of 100 ° C. or higher.

(Filler (D))
The filler (D) contained in the insulating sheet according to the present invention is not particularly limited as long as the thermal conductivity is 30 W / m · K or more. A filler (D) may be used independently and 2 or more types may be used together.

  The filler (D) having a thermal conductivity of 30 W / m · K or more is preferably at least one selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. . Especially, since heat dissipation can be improved further, spherical alumina and / or spherical aluminum nitride are more preferable.

  The average particle size of the filler (D) is preferably in the range of 0.1 to 40 μm. When the average particle size is less than 0.1 μm, high filling may be difficult, and when it exceeds 40 μm, the dielectric breakdown characteristics may be deteriorated.

  As a compounding quantity of the said filler (D), the range of 50-90 volume% is preferable in 100 volume% of insulating sheets. If the filler (D) is less than 50% by volume, the heat dissipation may not be sufficiently improved, and if it exceeds 90% by volume, the flexibility and adhesiveness of the insulating sheet may be significantly reduced.

(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 improve handling properties. However, even if these base materials are not included, the insulating sheet of the present invention is self-supporting even in an uncured state at room temperature (23 ° C.) and has excellent handling properties. 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, if necessary, the insulating sheet is laser processed, drilled, etc. These various processes can be easily performed. 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.

  The glass transition temperature (Tg) of the insulating sheet according to the present invention in an uncured state is preferably 25 ° C. or lower. 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.

  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 30-200 micrometers, Most preferably, it is 40-100 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 thermal conductivity after curing of the insulating sheet is preferably 2.0 W / m · K or more. More preferably, it is 3.0 W / m * K or more, More preferably, it is 5.0 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. 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 double-sided copper circuit laminated board or 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 a high thermal conductivity, heat from the conductive layer 2 side is easily transferred 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.

[Thermoplastic elastomer (A)]
(Synthesis Example 1)
In a pressure-resistant container substituted with dry nitrogen, 30 g of styrene monomer and 1000 g of cyclohexane as a solvent are added, 0.1 g of sec-butyllithium is added as a polymerization initiator, and the first stage polymerization is performed at 40 ° C. went.

  Thereafter, 5 g of tetrahydrofuran is added as a Lewis base, then 60 g of isobutylene and 30 g of styrene monomer are sequentially added, and the second stage polymerization is carried out to obtain a styrene-isobutylene-styrene trisylate having a styrene: isobutylene weight ratio of 50:50. A block copolymer 1 was obtained. The obtained triblock copolymer 1 had a weight average molecular weight (polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC)) of Mw = 100,000.

(Synthesis Example 2)
Synthesis except that the blending amount of styrene monomer in the first stage polymerization was changed to 15 g, the addition amount of isobutylene in the second stage polymerization was changed to 70 g, and the addition amount of styrene monomer was changed to 15 g. In the same manner as in Example 1, a styrene-isobutylene-styrene triblock copolymer 2 having a styrene: isobutylene weight ratio of 30:70 was obtained. The weight average molecular weight of the obtained triblock copolymer 2 was Mw = 70,000.

(Synthesis Example 3)
Synthesis except that the amount of styrene monomer added in the first stage polymerization was changed to 4 g, the amount of isobutylene added in the second stage polymerization was changed to 92 g, and the amount of styrene monomer added was changed to 4 g. In the same manner as in Example 1, a styrene-isobutylene-styrene triblock copolymer 3 having a styrene: isobutylene weight ratio of 8:92 was obtained. The weight average molecular weight of the obtained triblock copolymer 3 was Mw = 80,000.

(Synthesis Example 4)
A styrene-isobutylene-styrene triblock copolymer 4 having a styrene: isobutylene weight ratio of 60:40 was prepared in the same manner as in Synthesis Example 1 except that the amount of isobutylene added in the second stage polymerization was changed to 40 g. Obtained. The weight average molecular weight of the obtained triblock copolymer 4 was Mw = 92,000.

(Synthesis Example 5)
In the first stage of polymerization, 27 g of styrene monomer and 3 g of 4-aminostyrene were used instead of 30 g of styrene monomer, and in the second stage of polymerization, 27 g of styrene monomer instead of 30 g of styrene monomer, A styrene-isobutylene-styrene triblock copolymer 5 having a styrene: isobutylene weight ratio of aminostyrene = 50: 50 was obtained in the same manner as in Synthesis Example 1 except that 3 g of 4-aminostyrene was used. The weight average molecular weight of the obtained triblock copolymer 5 was Mw = 130,000.

(Synthesis Example 6)
After adding 20 g of 4,4′-diphenylmethane isocyanate and 60 g of both-terminal hydroxyl group-containing silicone (Mw = 30,000) in a pressure-resistant container substituted with dry nitrogen and dissolving at 70 ° C. to 90 ° C., 2 Stir for hours.

  After stirring, 20 g of neopentyl glycol was further added, the mixture was further stirred for 30 minutes and polymerized to obtain an aromatic polyurethane: silicone = 40: 60 aromatic polyurethane-silicone-aromatic polyurethane triblock copolymer 6. It was. The weight average molecular weight of the obtained triblock copolymer 6 was Mw = 52,000.

[Thermoplastic elastomers other than the thermoplastic elastomer (A)]
(Synthesis Example 7)
In a pressure-resistant container substituted with dry nitrogen, 50 g of styrene monomer and 1000 g of cyclohexane as a solvent are added, 0.1 g of sec-butyllithium is added as a polymerization initiator, and the first stage polymerization is performed at 40 ° C. went.

  Thereafter, 5 g of tetrahydrofuran was added as a Lewis base, and then 50 g of isobutylene was added, and the second stage polymerization was performed to obtain a styrene-isobutylene diblock copolymer 7 having a styrene: isobutylene weight ratio of 50:50. . The weight average molecular weight of the obtained diblock copolymer 7 was Mw = 120,000.

(Synthesis Example 8)
Synthesis except that the addition amount of styrene monomer in the first stage polymerization was changed to 3 g, the addition amount of isobutylene in the second stage polymerization was changed to 3 g, and the addition amount of styrene monomer was changed to 3 g. In the same manner as in Example 1, a styrene-isobutylene-styrene triblock copolymer 8 having a styrene: isobutylene weight ratio of 50:50 was obtained. The weight average molecular weight of the obtained triblock copolymer 8 was Mw = 11,000.

[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) Benzene skeleton oxetane resin (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 skeleton acid anhydride (trade name: Epicure YH-306, manufactured by Japan Epoxy Resin Co., Ltd.)
(5) Biphenyl skeleton phenolic resin (Madewa Kasei Co., Ltd., trade name: MEH-7851-S)
(6) Allyl skeleton phenol resin (product name: YLH-903, manufactured by Japan Epoxy Resin Co., Ltd.)
(7) Triazine skeleton phenolic resin (Dainippon Ink Chemical Co., Ltd., trade name: Phenolite KA-7052-L2)
(8) Melamine skeleton phenol 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)]
(1) Spherical alumina (Denka Co., Ltd., trade name: DAM-10, average particle size 10 μm, thermal conductivity 36 W / m · K)
(2) Boron nitride (manufactured by Showa Denko KK, trade name: UHP-1, average particle size 8 μm, thermal conductivity 60 W / m · K)
(3) Aluminum nitride (manufactured by Toyo Aluminum Co., Ltd., trade name: TOYALNITE-FLX, average particle size 14 μm, thermal conductivity 200 W / m · K)

[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 raw material was blended and kneaded in the proportions shown in Table 1 below (the blending unit is by weight) to prepare an insulating material.

  The insulating material was applied to a release PET sheet having a thickness of 50 μm 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 1-20 and Comparative Examples 1-4)
An insulating material was prepared in the same manner as in Example 1 except that the types and blending amounts of the raw materials used were as shown in Tables 1 and 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.

○: There is no deformation of the insulating sheet and it can be easily peeled. Δ: The insulating sheet can be peeled, but the sheet is stretched or broken.
In the evaluation of the handling property, the squares of the uncured insulating sheet after being peeled off from the PET sheet are fixed, and the insulating sheet is suspended in the air so that the squares are positioned in the horizontal direction. I left it alone. The deformation of the insulating sheet after being allowed to stand was observed, and the self-supporting property was evaluated according to the following criteria.

○: The insulation sheet is bent downward, and the insulation sheet is bent in the vertical direction (degree of deformation) within 5 cm. Δ: The insulation sheet is bent downward, and the insulation sheet is bent in the vertical direction ( Degree of deformation) exceeds 5 cm ×: Breaking occurs in the insulating sheet (3. Thermal conductivity)
The thermal conductivity of the insulating sheet was measured using a thermal conductivity meter “rapid thermal conductivity meter QTM-500” manufactured by Kyoto Electronics Industry Co., Ltd.

(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 strip of copper foil having a width of 10 mm, and the peeling strength when the copper foil is peeled from the substrate at a pulling speed of 50 mm / min at an angle of 90 ° C. 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 3 minutes △: Swelling and peeling occurred after 3 minutes passed and before 3 minutes passed. × Swelled and peeled before 1 minute passed. Tables 1 and 2 show.

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 (11)

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 thermoplastic elastomer (A), which is a block copolymer having at least two hard segments and at least one soft segment, 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) which is a phenol resin, or an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof or a modified product thereof;
Containing a filler (D) having a thermal conductivity of 30 W / m · K or more,
In a total of 100% by weight of the resin component in the insulating sheet containing the thermoplastic elastomer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), and the curing agent (C), The thermoplastic elastomer (A) is 20 to 60% by weight, the epoxy monomer (B1) and / or the oxetane monomer (B2) is 10 to 60% by weight, and the thermoplastic elastomer (A), The insulating sheet which is respectively contained in the ratio which the sum total with an epoxy monomer (B1) and / or the said oxetane monomer (B2) will be less than 100 weight%. The hard segment comprises at least one selected from the group consisting of styrene, aromatic urethane, alicyclic urethane, amide and imide, and
The soft segment contains a olefin hydrocarbon having 2 to 5 carbon atoms having no conjugated diene, a conjugated diene compound having 4 to 6 carbon atoms, a partially hydrogenated conjugated diene having 4 to 6 carbon atoms as a structural unit, and The insulating sheet according to claim 1, comprising at least one selected from the group consisting of silicone.   The insulating sheet according to claim 1 or 2, wherein a weight ratio of the hard segment to the soft segment (hard segment: soft segment) in the block copolymer is in the range of 10:90 to 50:50.   The insulating sheet according to any one of claims 1 to 3, wherein the hard segment has an epoxy group, an oxetanyl group, a (meth) acryloyl group, an amino group, a carboxyl group, or a hydroxyl group.   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 4, which is a modified product thereof. The insulating sheet according to claim 5, 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 4, 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 filler (D) according to any one of claims 1 to 7, wherein the filler (D) is at least one selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, and magnesium oxide. The insulating sheet described.   The insulating sheet according to any one of claims 1 to 7, wherein the filler (D) is spherical alumina and / or spherical aluminum nitride.   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 1-9. A laminated structure formed by curing an insulating sheet.   The laminated structure according to claim 10, wherein the high thermal conductor is a metal.

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