JP4689317B2 - Electrical insulating resin composition and laminate for circuit board using the same - Google Patents

Description

  The present invention relates to an electrically insulating resin composition that can be suitably used as an electrically insulating material in a circuit board such as a printed wiring board, and a laminate for a circuit board using the same, and in particular, has excellent flexibility. The present invention relates to an electrically insulating resin composition capable of forming an electrically insulating layer having high heat resistance at the same time, and a laminate for a circuit board using the same. More specifically, the present invention is an electrically insulating resin composition suitable for use in a metal base circuit board having excellent heat dissipation, excellent in solder heat resistance, and long-term even in a severe environment of high temperature and high humidity. The present invention relates to an electrically insulating resin composition capable of forming an electrically insulating layer that can be used stably over a wide range, a laminate for a circuit board using the same, and a laminate for a circuit board using the same.

  In recent years, there has been a demand for miniaturization, space saving, and high added value of home appliances, industrial equipment, OA equipment, and on-vehicle electronic equipment, and insulation that can withstand use in harsh temperatures, humidity, and electrical environments. There is a demand for materials, and in particular, an electrical insulation material having high electrical insulation, voltage resistance, heat dissipation, and high connection reliability in a soldered portion of a component is desired.

  As a circuit board used in such a harsh environment, a metal base circuit board in which an electrically insulating layer is provided on a metal board such as aluminum or copper having high heat dissipation and a conductive circuit is provided thereon is often used. ing.

  In such a metal base circuit board, an epoxy resin is often used as an electrical insulating layer. However, since the epoxy resin itself has low thermal conductivity, heat generated on the conductive circuit is efficiently transmitted to the metal board. I can't. Therefore, the thermal conductivity of the electrical insulating layer is improved by highly filling the epoxy resin with a thermally conductive inorganic filler.

  However, when the blending ratio of the inorganic filler is increased for the purpose of improving the thermal conductivity, there is a problem that the flexibility of the electrical insulating layer is lowered and becomes brittle, and the adhesion of the electrical insulating layer to the metal substrate is also decreased. In addition, when soldering a metal base circuit board, the treatment is performed at a high temperature of 200 ° C. or higher. However, if the blending ratio of the inorganic filler is high, defects are generated in the electrical insulating layer due to high heat during soldering, and withstand voltage resistance. It was also a factor that decreased.

For this reason, Patent Document 1 discloses a metal base circuit board using a resin composition having an elastic modulus of −40 ° C. of 2 × 10 ¹⁰ Pa or less as a measure for improving the flexibility and adhesion of the electrical insulating layer. As such a low elastic modulus resin composition, an epoxy resin in which a rubber component is dispersed is disclosed. Patent Document 1 exemplifies CTBN (carboxyl-terminated butadiene-acrylonitrile rubber) modified epoxy resin, epoxy resin blended with a modified polyamine flexible curing agent, and the like as specific examples of the epoxy resin in which the rubber component is dispersed. Yes. However, since the ionic impurities are contained in the electrical insulating layer obtained by using such a low elastic modulus epoxy resin, the created circuit is electrically and physically resistant to ion migration and water absorption. The deterioration of characteristics was inevitable. In Patent Document 1, the cured epoxy resin is handled in a semi-cured state (B stage state), but the material in the B stage state has a short life and is difficult to manage and store.

  Patent Document 2 discloses that an insulating adhesive layer material excellent in thermal conductivity, moisture resistance, heat resistance, insulation reliability, and crack resistance has an epoxy resin having a glass transition point of 0 ° C. or less and a molecular weight of 100,000 to A low-modulus thermal conductive adhesive composition to which acrylic rubber having a reactive group such as 2 million epoxy groups or NBR is added is disclosed. Such an epoxy-curing type insulating adhesive layer material is made by semi-curing the resin (B stage state) so that it does not stick even when touched by hand at room temperature, as in Patent Document 1. The handling is improved. However, the epoxy-curing type insulating adhesive layer material has a short life in the B stage state, and there are many difficult problems such as management and storage. Further, in the resin composition described in Patent Document 2, when the blending ratio of the inorganic filler is increased, the flexibility of the electrical insulating layer is lowered and becomes brittle, so that there is a problem that the inorganic filler cannot be filled with a high content. .

  On the other hand, Patent Document 3 discloses a thermosetting composition containing a polybutadiene resin or polyisoprene resin and an unsaturated polybutadiene or polyisoprene-containing polymer as an electrical insulating layer material utilizing a radical polymerization reaction. However, in Patent Document 3, since a 1,2-adduct is mainly used as the polybutadiene resin or polyisoprene resin or unsaturated butadiene or isoprene to be used, the obtained cured product is very hard and has an adhesive strength to the substrate. There was also a problem of being low.

  In addition, Patent Document 4 discloses a method for radical polymerization of a composition having an epoxy-modified rubber, an allyl group-containing compound, and a curable resin component such as bismaleimide. However, since Patent Document 4 mainly aims to provide a material having a low relative dielectric constant in order to improve the speed of signal processing, there is a drawback that the adhesiveness of the obtained electrical insulating layer is very low. Also, since the blending ratio of epoxy-modified rubber is small, the hardness is too high for applications that require flexibility. When a large amount of inorganic filler is blended, it is brittle and lacks insulation reliability. Is actually difficult to use.

Japanese Patent Laid-Open No. 11-8450 JP-A-10-242606 JP-A-8-208856 JP 2001-81429 A

  The present invention has been made in view of the above, and has excellent flexibility and adhesion to a substrate, and has both high heat resistance and moisture resistance, and can withstand high heat treatment during soldering. An electrically insulating resin composition capable of forming an electrically insulating layer that can be stably used over a long period of time in a severe environment of high temperature and humidity such as an engine room, and a laminate for a circuit board using the same The purpose is to provide.

  In order to solve the above problems, the present inventors have intensively studied, and as a result, a rubbery polymer compound (I) comprising a copolymer of a diene monomer and a polymerization having one or more double bonds at the terminal. The electrically insulating resin composition containing the conductive monomer (II), the crosslinking agent (III), and the thermally conductive inorganic filler (IV) has excellent flexibility, adhesion, moisture resistance, and heat deterioration resistance. The inventors have found that an electrical insulating layer provided with can be formed, and have completed the present invention. Furthermore, the electrically insulating resin composition of the present invention is characterized by using an olefin copolymer rubber, butyl rubber, or a mixture thereof as the rubbery polymer compound (I) comprising a copolymer of a diene monomer. To do.

  Conventionally, when a large amount of an inorganic filler is filled, an electrically insulating layer made from an electrically insulating resin composition becomes brittle and lacks insulation reliability, so that it has been difficult to use as an insulating material for heat dissipation. In contrast, in the present invention, the electrically insulating resin composition contains a rubbery polymer compound (I) made of a copolymer of a predetermined diene monomer, so that a large amount of thermally conductive filler is contained. Even in such a case, it is possible to form an electrically insulating layer that has high heat resistance and moisture resistance and is stable over a long period of time even in a severe environment of high temperature and high humidity without impairing flexibility.

  In the present invention, the iodine value of the rubber-like polymer compound (I) is preferably 25 or less. When the iodine value exceeds 25, a part of the unsaturated group of the rubber-like polymer compound (I) remains in an unreacted state, and this unreacted unsaturated group is oxidized by a high temperature during soldering. In particular, when used in a high-temperature environment, it becomes a factor that degrades the insulating properties of the electrical insulating layer due to oxidation degradation. In order to prevent such insulation deterioration of the electrical insulating layer, the iodine value of the rubbery polymer compound (I) is set to 25 or less.

  The electrically insulating resin composition according to the present invention can further contain an unsaturated cyclic oligomer compound (V). The unsaturated cyclic oligomer compound (V) acts as a compatibilizer between the rubbery polymer compound (I) and the polymerizable monomer (II), and has a structure in which these three components are polymerized more uniformly. In this case, the local heat loss does not occur, and the withstand voltage characteristics due to thermal degradation of the electrically insulating resin composition can be further improved.

  The electrically insulating resin composition according to the present invention can form an electrically insulating layer of a circuit board by being cured after being formed into a layer on a metal substrate. Since the electrically insulating resin composition according to the present invention contains a large amount of the heat conductive inorganic filler (IV) and has high heat resistance and moisture resistance due to the rubbery polymer compound (I), the environment is particularly severe. When used as an electrical insulating layer of a circuit board used below, excellent insulating properties and environmental resistance are obtained.

  The laminate for a circuit board according to the present invention is characterized by having a metal layer on at least one surface of an electrical insulating layer obtained by curing the above-described electrical insulating resin composition. The metal layer is, for example, a wiring layer metal (conductor) foil or a metal substrate. As the laminate for a circuit board of the present invention, a laminate for a circuit board having a three-layer structure in which a metal substrate, an electric insulation layer and a metal conductor foil are laminated in this order, a metal conductor foil and an electric insulation layer are laminated in this order. A laminate for a circuit board having a two-layer structure and a laminate for a circuit board having a three-layer structure in which a metal conductor foil, an electrical insulating layer, and a metal conductor foil are laminated in this order can be given.

  A laminate for a circuit board having a three-layer structure in which a metal substrate, an electrical insulating layer, and a metal conductor foil are laminated in this order is used for manufacturing a metal base circuit board. Also, for a circuit board laminate having a two-layer structure in which a metal conductor foil and an electric insulation layer are laminated in order, and for a circuit board having a three-layer structure in which a metal conductor foil, an electric insulation layer and a metal conductor foil are laminated in this order The laminate is used for an inner layer circuit of a multilayer circuit board.

  The electrically insulating resin composition of the present invention comprises a copolymer of a diene monomer, and in particular, the rubbery polymer (I) having an iodine value of 25 or less has almost completely polymerized double bonds in the molecule. Used for polymerization reaction with the polymerizable monomer (II). Therefore, the amount of unreacted unsaturated groups remaining in the electrical insulating layer can be greatly reduced, and the oxidation deterioration resistance due to heating of the electrical insulating layer can be greatly improved.

  In addition, by using a crosslinkable rubber-like polymer compound (I), even if a large amount of thermally conductive inorganic filler (IV) such as alumina is filled in order to improve heat dissipation, the flexibility is maintained and processed. An electrically insulating layer or an electrically insulating material having good properties can be obtained. In addition, by appropriately combining the resin composition, the adhesiveness, withstand voltage, flexibility, and the like of the electrical insulating material can be provided according to the required characteristics.

  Furthermore, since a radical polymerization reaction or other polymerization reaction is used, B stage management like an epoxy resin is not required at all, storage stability is dramatically increased, and handling is facilitated. In addition, the curing time during the production of the cured laminate can be shortened, which is useful for improving productivity and saving energy.

  Since the laminate for a circuit board according to the present invention includes an electrical insulating layer with greatly improved thermal conductivity, heat resistance, and moisture resistance, it has excellent insulating properties and environmental resistance even in a severe environment. It can be used as a circuit board having

  Hereinafter, embodiments of the electrically insulating resin composition and the laminate for a circuit board according to the present invention will be described in detail. The present invention is not limited to the following embodiments.

[A] Electrically Insulating Resin Composition The electrically insulating resin composition of the present invention has a rubbery polymer (I) composed of a copolymer of a diene monomer and one or more double bonds at the terminal. A resin composition containing a polymerizable monomer (II), a crosslinking agent (III), and a heat conductive inorganic filler (IV).

  First, the crosslinkable rubber-like polymer compound (I) is a rubber-like polymer compound copolymerized with a diene monomer. Examples of such a rubber-like polymer compound (I) include olefin copolymer rubber (1) and butyl rubber ( 2). Examples of the olefin copolymer rubber (1) include ethylene-α-olefin-nonconjugated diene copolymers, and examples of the butyl rubber (2) include vinyls such as isobutylene-isoprene copolymer, halogenated butyl rubber, and styrene. Examples thereof include terpolymers of aromatic compounds and isobutylene-isoprene.

  The olefin copolymer rubber (1) that can be cross-linked is an amorphous and random elastic copolymer having a C 2-20 α-olefin content of 50 mol% or more, or a crystallinity of 50%. The following elastic copolymers include copolymers of two or more α-olefins and non-conjugated dienes.

  Specific examples of such olefin copolymer rubber (1) include ethylene-α-olefin-nonconjugated diene copolymer rubber.

  Here, specific examples of the α-olefin include ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3 -Methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3 -Ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and combinations thereof It is. Specific examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene, and ethylidene norbornene.

  These olefin-based copolymer rubbers (1) are preferably those having a Mooney viscosity [ML1 + 4 (100 ° C.)] of 10 to 240 from those which are liquid at room temperature. The lower the viscosity, the better the coating property of the solution, so that it can be selected within the range permitted by physical properties such as adhesiveness. The ethylene-α-olefin-nonconjugated diene copolymer rubber preferably has an iodine value of 25 or less. A preferable range of the iodine value will be described later.

  Examples of the crosslinkable butyl rubber (2) include a copolymer mainly composed of isobutylene and isoprene, and a halogenated butyl rubber obtained by adding chlorine or bromine to butyl rubber. Furthermore, a terpolymer of vinyl aromatic monomer such as styrene and isobutylene-isoprene can be used. These butyl rubbers (2) and the like are preferably those having a Mooney viscosity [ML1 + 4 (100 ° C.)] of about 60 from those which are liquid at room temperature.

  The degree of unsaturation is variable depending on the copolymer ratio of isoprene, but the iodine value of the rubbery polymer compound (I) including the olefin copolymer rubber (1) and the butyl rubber (2) is 25 or less. Are preferable, 3-20 are more preferable, and 5-20 are more preferable. If the iodine value is less than 3, poor curing of the resin composition occurs, the T peel strength decreases and the solder heat resistance decreases, which may not be suitable depending on the environment used. Further, since the degree of crosslinking of the polymer is lowered, it tends to swell with a solvent, which is not preferable. On the other hand, when the iodine value exceeds 25, an unsaturated bond tends to remain even after the resin composition is cured, which is not preferable because the withstand voltage after heat treatment is lowered.

  Butyl rubber (2) or the like is suitable as an insulating material because it has low gas permeability such as steam and good electrical insulation. Butyl rubber (2) is blended with EPDM (ethylene-propylene rubber), hydrogenated SBS (styrene-butadiene-styrene block copolymer), hydrogenated SIS (polystyrene-polyisoprene-polystyrene block copolymer), etc. Co-crosslinking is possible, and it can also be added to improve the gas permeability, electrical insulation and vibration damping properties of the rubber-like polymer compound (I).

  Furthermore, the crosslinkable rubbery polymer compound (I) has polar groups such as carboxylic acid groups, acid anhydride groups, amino groups, hydroxyl groups, and epoxy groups, and bonds such as urethane bonds, ester bonds, and amide bonds. The modified product introduced can also be suitably used because it can improve the adhesion to the metal layer described later.

  In the present invention, the olefin copolymer rubber (1) or butyl rubber (2) may be used alone, and two or more olefin copolymer rubbers having different monomer composition ratios and molecular weights of the copolymer. It is also possible to use (1) and butyl rubber (2) in combination. By using two or more rubbery polymer compounds (I) in combination, the compatibility, adhesiveness, flexibility, electrical properties, etc. of the electrically insulating resin composition can be adjusted.

  Next, as the polymerizable monomer (II) (unsaturated compound) having one or more carbon-carbon double bonds at the terminal, a compound that can be crosslinked by a peroxide or the like can be used. As such a compound, for example, a compound having a highly reactive double bond such as a vinyl group, an allyl group, a methallyl group, an acrylic group or a methacryl group at the terminal, a conjugated diene, a non-conjugated diene, or the like is used. be able to.

  Specific examples of such polymerizable monomer (II) include divinyl heptane, divinyl octane, divinyl nonane, vinyl benzene, divinyl benzene, bisphenol A type epoxy acrylate, methyl methacrylate, isobornyl acrylate, tricyclodecane dimethacrylate, tri Examples include allyl isocyanurate, ethoxylated isocyanuric acid triacrylate, butadiene, isobutylene, pentadiene, hexadiene, octadiene, nonadiene, decadiene, dicyclopentadiene, ethylidene norbornene and the like. In particular, isobornyl acrylate, tricyclodecanedimethacrylate, triallyl isocyanurate, ethoxylated isocyanuric acid triacrylate, and cycloaliphatic compounds obtained by hydrogenating aromatic rings contained in these molecules As described above, it is preferable to use a monomer having a cyclic structure in the molecule. By using a monomer having a cyclic structure such as a cycloaliphatic compound, an aromatic ring compound, or a heterocyclic compound, the compatibility and heat resistance of the electrically insulating resin composition can be further improved.

  Furthermore, by introducing polar groups such as carboxylic acid group, amino group, hydroxyl group and epoxy group, and bonds such as urethane bond, ester bond and amide bond into the above-mentioned polymerizable monomer (II), electrical insulation is achieved. This is preferable because the adhesion between the conductive resin composition and the metal layer described later can be improved.

  The molecular weight of the polymerizable monomer (II) is not particularly limited, but the molecular weight Mw is preferably 50 to 500, and more preferably 100 to 350.

  Since the polymerizable monomer (II) is mainly related to the flowability and the crosslinking reaction in the electrically insulating resin composition, it is necessary to sufficiently consider the compatibility depending on the composition used.

  In the electrically insulating resin composition of the present invention, it is possible to add an unsaturated cyclic oligomer (V) having good compatibility with the rubbery polymer compound (I) and the polymerizable monomer (II). The unsaturated cyclic oligomer compound (V) acts as a compatibilizer between the rubbery polymer compound (I) and the polymerizable monomer (II), and has a structure in which these three components are polymerized more uniformly. Due to the effects that are considered to be caused by the fact that local heating loss does not occur and microvoids do not occur in the electrical insulating layer, the withstand voltage characteristics due to thermal degradation of the electrical insulating resin composition can be further improved. Therefore, the electrically insulating resin composition according to the present invention can be suitably used for applications that require heat resistance. In addition, when the unsaturated cyclic oligomer (V) that is solid at room temperature is used, the adhesiveness of the uncured product can be suppressed, and there is also an effect that the workability is improved because there is no stickiness in the production of the laminated material. It is done.

  As the unsaturated cyclic oligomer (V), it is preferable to use a compound having a cyclic structure such as aromatic, cycloaliphatic or heterocyclic in the molecule. Examples of the cyclic skeleton contained in the molecule include coumarone, indene, rosin, cyclopentane, cyclopentene, cyclohexane, cyclohexene, tricyclodecane, norbornene, isocyanuric acid, triazine and the like. Among these, oligomers having an alicyclic structure (cycloaliphatic) such as rosin, cyclopentane, cyclopentene, cyclohexane, cyclohexene, tricyclodecane and norbornene have a compatibilizing action compared to aromatic and heterocyclic oligomers. Is preferable because the heat resistance of the cured product can be further improved.

  The unsaturated cyclic oligomer (V) used in the present invention is a polymer of a polymerizable monomer having a cyclic structure, or a copolymer of a polymerizable monomer having a cyclic structure and an aliphatic unsaturated compound, or These ester compounds can also be used.

  Specific examples of the unsaturated cyclic oligomer compound (V) include (1) 5-ethylidene-2-norbornene and dicyclopentadiene, which are cyclic aliphatic compounds, or styrene and vinyl toluene, which are aromatic vinyl compounds. And aliphatic unsaturated compounds such as 1,4-hexadiene, isobutylene and 1,3-pentadiene, and diene unsaturated mixtures called C5 fractions, (2) such as rosin derivatives Examples include condensation polymers or esterified products thereof, (3) dimer acids or modified products, (4) copolymers such as coumarone indene resin, and (5) polymers of triallyl isocyanurate.

  The unsaturated cyclic oligomer (V) preferably has one or more unsaturated bonds in the molecule, and preferably has a bromine number of 25 or more. By using an oligomer having such a reactive unsaturated bond, the compatibility of the electrically insulating resin composition and the uniformity of the reaction can be further enhanced.

  Furthermore, by introducing polar groups such as carboxylic acid groups, amino groups, hydroxyl groups, and epoxy groups, and bonds such as urethane bonds, ester bonds, and amide bonds into the unsaturated cyclic oligomer (V), electrical insulation is achieved. This is preferable because the adhesion between the electrical insulating layer obtained by curing the resin composition and the metal layer described later can be improved.

  The molecular weight Mw of the unsaturated cyclic oligomer (V) is preferably 300 to 10,000, and more preferably 400 to 1,000. By further using the unsaturated cyclic oligomer (V) having a molecular weight corresponding to the intermediate molecular weight of the rubbery polymer compound (I) and the polymerizable monomer (II), the compatibility of the electrically insulating resin composition is further enhanced. Can do.

  Moreover, it is preferable to use a solid unsaturated cyclic oligomer at room temperature from the viewpoint of quality stability that lowers the tackiness of the uncured product of the electrically insulating resin composition.

  Here, since the preferable blending ratio of the crosslinkable rubber-like polymer compound (I) and the polymerizable monomer (II) varies depending on the kind of the compound, it is difficult to define it generally. It is preferable to blend the component of the molecular compound (I) as a main component. Specifically, the rubbery polymer compound (I) component is added in an amount of 50 to 95 parts by weight with respect to 100 parts by weight of the rubbery polymer compound (I) component and the polymerizable monomer (II) component. II) It is preferable to mix | blend a component in the ratio of 50-5 weight part. When the unsaturated cyclic oligomer (V) is added, the rubbery polymer compound (I) component is 50 to 80 parts by weight, the polymerizable monomer (II) component is 40 to 10 parts by weight, and the unsaturated cyclic oligomer. (V) It is preferable to contain a component in the ratio of 40-10 weight part.

  Next, in the electrically insulating resin composition of the present invention, a thermally conductive inorganic filler (IV) is added in order to improve thermal conductivity. Examples of the thermally conductive inorganic filler (IV) include silica, alumina, aluminum nitride, boron nitride, silicon carbide, and silicon nitride. The particle diameter, particle size distribution, shape, and filling amount that are optimal for blending are determined and blended. be able to. The blending amount of the thermally conductive inorganic filler (IV) is 40% to 90%, preferably 50% to 75% by volume, with respect to the volume of the electrically insulating resin composition (including the thermally conductive inorganic filler). % Blended. If the volume fraction of the thermally conductive inorganic filler (IV) is less than 40%, the improvement in thermal conductivity in the electrically insulating resin composition is not sufficient, which is not preferable. On the other hand, if the volume fraction exceeds 90%, the flexibility of the electrical insulating layer decreases and the workability deteriorates, which is not preferable.

  Here, what should be noted in the present invention is that the content of the heat-conductive inorganic filler (IV) compared to the conventional one by containing the predetermined rubber-like polymer compound (I) in the electrically insulating resin composition. Can be greatly increased. That is, since the rubber-like polymer compound (I) of the present invention is very effective in ensuring the flexibility of the electrical insulating layer, the thermally conductive inorganic filler (IV) is used for the electrical insulating resin composition. A large amount can be added. Therefore, the thermal conductivity of the electrical insulation layer can be greatly improved, and the workability can be maintained well without impairing the flexibility of the electrical insulation layer.

  Next, the electrically insulating resin composition of the present invention can be cured by radical polymerization reaction or other polymerization reaction using the crosslinking agent (III), and any of these polymerization reactions can be employed. . In addition, when making it harden | cure by radical polymerization reaction, the radical polymerization initiator normally used for an electrically insulating resin composition is added.

  As radical polymerization initiators, organic peroxides such as diacyl peroxide, alkyl peroxy ester, peroxy dicarbonate, monoperoxy carbonate, peroxy ketal, dialkyl peroxide, hydroperoxide, ketone peroxide, perbenzoic acid Examples include acid, t-butyl peroxide, dicumyl peroxide, azobisisobutyronitrile and azobis-1-cyclohexanenitrile which are azobis compounds, but the present invention is not limited thereto.

  The addition amount of the radical polymerization initiator is preferably 0.1 to 10 parts by weight with respect to a total of 100 parts by weight of the rubbery polymer compound (I) and the polymerizable monomer (II), and ranges from 1 to 5 parts by weight. It is more preferable because a good cured product can be obtained. Also when the unsaturated cyclic oligomer (V) is added, the radical polymerization initiator may be added in the same manner as described above.

  As other crosslinking agents (III), dipentamethylene tetrasulfide, dithiomorpholine, brominated alkylphenol formaldehyde resin, methylolated phenol formaldehyde resin, p-quinonedioxim, etc. should be used according to the composition of the electrically insulating resin composition. Can do.

  In addition, when the thermally conductive inorganic filler (IV) is filled, a silane coupling agent exemplified by epoxy silane, aminosilane, methacryloxysilane, titanate, aluminum coupling agent, etc. for the purpose of surface modification. The inorganic material of the thermally conductive inorganic filler (IV) is subjected to surface treatment in advance or is blended in the electrically insulating resin composition, so that it is a thermally conductive inorganic filler (IV), glass cloth, metal layer. The adhesive force between the copper foil and the resin composition can be improved.

  In addition, when an electrically insulating resin composition is impregnated into a glass cloth or the like, or coated on a support such as a peelable film, a metal conductor foil or a metal substrate, the coating property of the electrically insulating resin composition is improved. In order to adjust, it is preferable to dilute the electrically insulating resin composition of the present invention using an organic solvent.

  Examples of the organic solvent used include methanol, ethanol, propanol, isopropanol, methyl acetate, ethyl acetate, benzene, toluene, xylene, acetone, methyl ethyl ketone, diethyl ether, dioxane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, and chlorobenzene. Etc., and one or more of these are appropriately selected and used.

  In addition, in order to improve the performance of the electrically insulating resin composition, various additives may be added as long as the required performance is not impaired. As an additive, for example, an ion adsorbent for improving ion migration resistance, an anti-aging agent for preventing oxidative degradation, a flame retardant for increasing flame retardancy, and the like can be added.

  The rubber-like polymer compound (I), the polymerizable monomer (II), the crosslinking agent (III), the thermally conductive inorganic filler (IV), and the unsaturated cyclic oligomer added as necessary, which are the components described above By uniformly mixing the compound (V), the electrically insulating resin composition of the present invention can be prepared.

[B] Circuit Board Laminate Next, the circuit board laminate according to the present invention will be described. The laminate for a circuit board according to the present invention has a metal layer on at least one surface of an electrical insulating layer formed by curing the above-described electrical insulating resin composition. Here, a metal base material, a metal substrate, metal foil, etc. can be used for a metal layer. Although the electrically insulating resin composition of the present invention can be used without limitation as an electrically insulating material in a known circuit board, it can be suitably used particularly as an electrically insulating material in a metal base circuit board. Hereinafter, a metal base circuit board will be described as an example.

  The laminate for a metal base circuit board of the present invention is a cured laminate obtained by laminating a metal base material, an electric insulation layer and a metal conductor foil in this order, and the electric insulation layer of the electric insulating resin composition of the present invention. It consists of hardened | cured material, It is characterized by the above-mentioned. In use, the circuit board can be formed by subjecting the surface metal conductor foil to a general circuit forming process such as etching. Further, by forming an electrical insulating layer and a metal conductor foil on the circuit formation surface of the circuit board, and further subjecting the surface metal conductor foil to a circuit formation process, the circuit board can be used as a multilayer circuit board.

  The electrical insulating layer is obtained by thermally curing the electrical insulating resin composition of the present invention by radical polymerization reaction or other polymerization reaction. The preferable curing temperature condition is 120 to 250 ° C., and the pressure is 2 to 5 MPa.

  The method for forming the laminate for a metal base circuit board of the present invention is not particularly limited. For example, the electrically insulating resin composition is directly applied onto a metal substrate or a metal conductor foil, and the electrically insulating resin composition is heated. It can be formed by pressure curing. Alternatively, a prepreg sheet in which a glass cloth or the like is impregnated with an electrically insulating resin composition may be sandwiched between a metal substrate and a metal conductor foil and cured by heating and pressing. Also, an electrically insulating resin composition is applied onto the peelable film to form an uncured electrical insulating layer, and the peelable film is peeled off from the uncured electrical insulating layer to form a metal substrate or a metal conductor foil. An uncured electrical insulation layer may be disposed between the layers, and the uncured electrical insulation layer may be formed by heating and pressure curing.

  In addition, the electrically insulating resin composition of the present invention can also be used as a cured product for a circuit board as described below. For example, you may use as a laminated body for circuit boards which provides metal conductor foil in the at least one surface of the electrically insulating layer which consists of hardened | cured material of the electrically insulating resin composition of this invention. Such a laminate for a circuit board can be used for the production of a multilayer circuit board by subjecting a metal conductor foil on the surface to a circuit forming process and sequentially stacking and integrating them.

  When manufacturing a laminate for a single-sided circuit board in which a metal conductor foil is provided on one side of the electrical insulating layer, the metal conductor foil is combined on one side of the above-described prepreg sheet or adhesive sheet, and heat-cured with a hot press or the like. Can be manufactured. It can also be produced by forming an uncured laminate in which a coating film (uncured electrical insulation layer) is formed using an electrically insulating resin composition on a metal conductor foil, and heating and curing this. .

  Moreover, when manufacturing the laminated body for double-sided circuit boards which provided the metal conductor foil on both surfaces of the electrically insulating layer, in the state which has arrange | positioned the metal conductor foil on both surfaces of the above-mentioned prepreg sheet or an adhesive sheet, or an uncured laminated body In this case, it can be obtained by heat-curing with a hot press or the like in a state where the metal conductor foil is further arranged on the opposite side of the surface on which the metal conductor foil is formed.

  The thickness of the electrically insulating layer after curing is preferably 10 to 300 μm in view of general required characteristics, and is industrially useful particularly in the range of 50 to 150 μm.

  As the metal substrate, a metal substrate such as aluminum or copper can be used. The thickness of the metal substrate is 0.1 mm to 5 mm, preferably 0.5 mm to 3 mm.

  As the metal conductor foil for forming the wiring layer, a metal foil such as copper or aluminum can be used, and the thickness of the metal conductor foil is 5 to 500 μm, preferably 35 to 300 μm.

[C] Forming Material of Circuit Board Laminate Next, a forming material (uncured laminate) for forming the circuit board laminate of the present invention will be described. This uncured laminate is a laminate used for the production of a circuit board, and comprises an uncured electrical insulating layer obtained from the electrically insulating resin composition of the present invention and a metal layer (metal conductor foil for wiring layers). Or a metal substrate). That is, the uncured laminate of the present invention is used for simultaneously forming an electrical insulating layer and at least one layer selected from a metal substrate or a metal conductor foil for a wiring layer.

  The main supply form of the forming material for forming the laminate for a circuit board of the present invention is as follows: (1) Sheet-like material that is an uncured sheet-like material used for forming an electrical insulating layer in a circuit board An uncured product and (2) an uncured laminate having a two-layer structure for forming an electrical insulating layer and one metal layer selected from a metal conductor foil for a metal substrate or a wiring layer in a circuit board Can be mentioned. In addition, about these formation materials, although it can utilize suitably for manufacture of the hardening laminated body for metal base circuit boards, the use is not limited to this.

  As the sheet-like uncured material of (1), an adhesive sheet in which an uncured electrical insulating layer is formed by applying an electrically insulating resin composition on (i) a prepreg sheet and (ii) a peelable film. Can be mentioned.

  The prepreg sheet (i) is obtained by impregnating a fiber sheet with the electrically insulating resin composition of the present invention. In use, in a state where the metal conductor foil is superimposed on one side or both sides of the prepreg sheet, or in a state where the metal conductor foil is arranged on one side of the prepreg sheet and the metal substrate is arranged on the other side. By thermally pressing the body, the electrically insulating resin composition soaked in glass cloth or the like is cured to form an electrically insulating layer. A cured laminate in which a metal conductor foil is laminated on both surfaces of a prepreg sheet and the electrically insulating resin composition is cured can be suitably used for an inner layer circuit of a multilayer circuit board.

  As a fiber sheet used for preparation of the prepreg sheet (i), an organic or inorganic woven fabric or non-woven fabric can be used. A glass cloth etc. can be used as an inorganic fiber sheet. As the organic fiber sheet, a fiber sheet made of polyimide, aramid, heat resistant polyester, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), carbon fiber, or the like can be used.

  The prepreg sheet (i) can be formed by diluting the electrically insulating resin composition of the present invention to an appropriate concentration with an organic solvent or the like, impregnating it with a glass cloth or the like, and then drying it. The thickness of the glass cloth or the like is preferably 30 to 200 μm, more preferably 60 to 100 μm, and the adhesion amount of the electrically insulating resin composition can be adjusted according to the application.

  The adhesive sheet (ii) is an adhesive sheet in which an uncured electrical insulating layer made of the electrical insulating resin composition of the present invention is formed on a peelable film. In actual use, the peelable film is peeled off and an uncured electrical insulating layer is sandwiched between a metal substrate and a metal conductor foil, and then cured by heating and pressing, so that it can be used for a metal base circuit board. Furthermore, it can utilize as a hardening laminated body for the inner layer circuits in a multilayer circuit board by heat-pressing in the state which accumulated the metal conductor foil on the single side | surface or both surfaces.

  This adhesive sheet (ii) can be obtained, for example, by applying the electrically insulating resin composition of the present invention on a peelable film and drying the resulting coating film. Examples of the peelable film include olefin films such as polyethylene and polypropylene, fluororesin films, polyethylene terephthalate films, and triacetyl cellulose. Those obtained by imparting peelability to these films with a silicone resin or the like are preferably used. This film preferably has a thickness of 10 to 200 μm, more preferably 30 to 100 μm.

  The uncured laminate having the two-layer structure (2) includes (i) an uncured electrical insulating layer obtained from the electrically insulating resin composition of the present invention on a metal plate serving as a metal substrate in a circuit board. (Ii) An uncured electrical insulating layer obtained from the electrical insulating resin composition of the present invention is formed on a two-layer laminate or (ii) a metal conductor foil serving as a wiring layer in a circuit board. A layer structure laminate can be given. When producing such an uncured laminate, it can be produced by applying the electrically insulating resin composition of the present invention on a metal substrate or metal conductor foil and drying the resulting coating film. it can.

  In the case of an uncured laminate in which an uncured electrical insulation layer is formed on a metal conductor foil, the uncured electrical insulation layer is heated and pressed in a state where the uncured electrical insulation layer is disposed on the metal substrate, and the uncured electrical insulation layer is formed on the metal substrate. A three-layer laminate composed of a metal substrate, an electrical insulating layer, and a metal conductor foil is formed by sticking to the substrate. Moreover, it can utilize as a hardening laminated body for the inner layer circuits in a multilayer circuit board by carrying out thermocompression bonding in the state which accumulated the metal conductor foil on the uncured electrical insulation layer.

  In the case of a laminate in which an uncured electrical insulation layer is formed on a metal substrate, the uncured electrical insulation layer is made into a metal conductor by heating and pressing with a metal conductor foil placed on the uncured electrical insulation layer. By sticking to the foil, a three-layer laminate is formed by laminating the metal substrate, the electrical insulating layer, and the metal conductor foil in this order.

  The above-mentioned (1) sheet-like uncured product and (2) the uncured electrical insulating layer in the uncured laminate can be provided with a protective film as necessary, and are preferably peeled off during use. As the protective film, the above-described peelable film or the like is used.

  Hereinafter, based on an Example and a comparative example, it demonstrates further more concretely about this invention. In addition, this invention is not limited to the following Example.

Example 1
Liquid EPDM (Uniroy Chemical Co .: Trilene # 65, ethylene / propylene ratio = 48/52, molecular weight = 40000, iodine value = 20) as rubbery polymer (I), 60 parts by weight, polymerizable monomer (II) 40 parts by weight of triallyl isocyanurate (TAIC) as a component, 3.5 parts by weight of a silane coupling agent (Shin-Etsu Chemical Co., Ltd .: KMB503), and dicumyl peroxide (DCP) as a radical polymerization initiator as a crosslinking agent (III) ) 3.0 parts by weight was dissolved in 250 parts by weight of toluene.

  Next, 60% by volume of alumina powder (Showa Denko: S50 average particle size 9 μm) is added as a thermally conductive inorganic filler (IV) to 40% by volume of the resin composition in the solution to obtain an electrically insulating resin composition. Prepared. The obtained solution was impregnated into a glass cloth having a thickness of 70 μm to produce a prepreg having a thickness of 100 μm. This is set between a 35 μm copper foil and an aluminum substrate having a thickness of 1.0 mm, and heated and cured at 180 ° C. and 5 MPa for 30 minutes with a hot press, and from three layers of an aluminum substrate, an electrical insulating layer and a copper foil. A laminate was produced.

(Example 2)
60 parts by weight of EPDM # 4010 (Mitsui Chemicals Co., Ltd .: ethylene / propylene / diene ratio = 63 / 26.4 / 10.6, iodine value = 22), which is a solid ethylene / propylene rubber, as the rubbery polymer compound (I) 20 parts by weight of dicyclopentadiene-based petroleum resin (Nippon Zeon: QNT1345) as the oligomer compound (V), 20 parts by weight of triallyl isocyanurate (TAIC) as the polymerizable monomer (II) component, and a silane coupling agent ( Shin-Etsu Chemical Co., Ltd .: KMB503) was added to 3.5 parts by weight, and further, 3.0 parts by weight of dicumyl peroxide as a radical initiator as a crosslinking agent (III) was added to 250 parts by weight of toluene and dissolved.

  Next, 60% by volume of alumina powder (Showa Denko: S50 average particle size 9 μm) as heat conductive inorganic filler (IV) is added to 40% by volume of the resin composition in the solution, and the mixture is sufficiently stirred with a centrifugal de-stirrer. Thus, an electrically insulating resin composition was prepared. The obtained solution was applied to the back surface of a 35 μm thick copper foil with a bar coater and then dried in a heating oven at 80 ° C. for 10 minutes to disperse the solvent, thereby obtaining an electric insulating layer having a thickness of 100 μm. Next, an electrical insulating layer applied to a copper foil is overlaid on an aluminum substrate having a thickness of 1.0 mm, and heated and cured by heating at 180 ° C. and 5 MPa for 30 minutes. A laminate composed of three layers of copper foil was prepared.

(Example 3)
60 parts by weight of butyl rubber # 365 (Nippon Butyl: iodine value = 11) as the rubber-like polymer compound (I) and 20 parts by weight of dicyclopentadiene-based petroleum resin (Maruzen Petroleum: Marcaretsu M845A) as the oligomeric compound (V) As a polymerizable monomer (II), 20 parts by weight of tricyclodecane dimethanol dimethacrylate (Shin Nakamura Chemical: NKDCP), 3.5 parts by weight of an aluminum coupling agent (Ajinomoto: AL-M), and a crosslinking agent ( As III), 3.0 parts by weight of dicumyl peroxide as a radical polymerization initiator was added to 200 parts by weight of toluene and dissolved to prepare. Next, 50% by volume of aluminum nitride powder (Toyo Aluminum: UMK, average particle size 6.5 μm) was added as a thermally conductive inorganic filler (IV) to 50% by volume of the resin composition in the solution. An electrically insulating resin composition was prepared by sufficiently stirring with a stirrer. An insulating layer having a thickness of 100 μm was made from the obtained solution in the same manner as in Example 2, and a laminate was further produced.

Example 4
60 parts by weight of EP43 (ENB diene content of Japanese synthetic rubber: 1.5% by weight: iodine value = 3) as an ethylene-propylene rubber as the rubbery polymer compound (I), and dicyclopentadiene as the oligomeric compound (V) 20 parts by weight of petroleum resin (Nippon ZEON: QNT1345), 20 parts by weight of triallyl isocyanurate (TAIC) as polymerizable monomer (II), and 3.5 parts by weight of silane coupling agent (Shin-Etsu Chemical Co., Ltd .: KMB503) Further, 3.0 parts by weight of dicumyl peroxide as a radical initiator as a crosslinking agent (III) was dissolved in 250 parts by weight of toluene.

  Next, 50% by volume of alumina powder (Showa Denko: S50 average particle size 9 μm) is added as a thermally conductive inorganic filler (IV) to 50% by volume of the resin composition in the solution, and the mixture is sufficiently stirred with a centrifugal defoaming stirrer. Thus, an electrically insulating resin composition was prepared. The obtained solution was applied to the back surface of a 35 μm thick copper foil with a bar coater and then dried in a heating oven at 80 ° C. for 10 minutes to scatter the solvent to obtain a 100 μm electrically insulating layer. Next, an electrical insulating layer applied to a copper foil is overlaid on an aluminum substrate having a thickness of 1.0 mm, and heated and cured by heating at 180 ° C. and 5 MPa for 30 minutes. A laminate consisting of three layers of copper foil was produced.

(Comparative Example 1)
70 parts by weight of liquid isoprene rubber (Kuraray: LIR-50 iodine number = 368) as a rubbery polymer compound, 20 parts by weight of dicyclopentadiene petroleum resin (Maruzen Petroleum: Marcaretsu M845A) as an oligomer compound (V), polymerization 10 parts by weight of tricyclodecane dimethanol dimethacrylate (Shin Nakamura Chemical: NKDCP), 3.5 parts by weight of an aluminum coupling agent (Ajinomoto: AL-M), and a crosslinking agent (III) As a radical polymerization initiator, 3.0 parts by weight of dicumyl peroxide as a radical polymerization initiator was added to 200 parts by weight of toluene and dissolved to prepare.

  Next, 50% by volume of aluminum nitride (Toyo Aluminum: UMK average particle size 6.5 μm) is added as a thermally conductive inorganic filler (IV) to 50% by volume of the resin composition in the solution, and a centrifugal de-stirring stirrer is sufficient. An electrically insulating resin composition was prepared by stirring. From the obtained solution, an electrical insulating layer having a thickness of 100 μm was produced in the same manner as in Example 1. Furthermore, a laminate was produced in the same manner as in Example 2 using the obtained electrical insulating layer.

(Comparative Example 2)
70 parts by weight of SBS rubber (styrene, butadiene, styrene) (Asahi Kasei: Tufprene 125 iodine value = 205) as the rubbery polymer compound, and tricyclodecane dimethanol dimethacrylate (Shin Nakamura Chemical) as the polymerizable monomer (II) : NKDCP), 30 parts by weight of silane coupling agent (Shin-Etsu Chemical Co., Ltd .: KMB503), and 3.0 parts by weight of dicumyl peroxide as a radical polymerization initiator as a crosslinking agent (III) And dissolved in 250 parts by weight of toluene.

  Next, 60% by volume of alumina powder (Showa Denko: S50 average particle size 9 μm) is added as a thermally conductive inorganic filler (IV) to 40% by volume of the resin composition in this solution, and the mixture is sufficiently stirred with a centrifugal de-stirrer. Thus, an electrically insulating resin composition was prepared. An insulating layer having a thickness of 100 μm was formed from the obtained solution in the same manner as in Example 2, and a laminate was further prepared.

(Comparative Example 3)
70 parts by weight of ethylene-propylene rubber (ethylene: propylene = 48: 52, Mooney viscosity 40, iodine value = 0) containing no double bond as a rubbery polymer compound, and dicyclopentadiene petroleum as an oligomer compound (V) 20 parts by weight of resin (Maruzen Petroleum: Marcaretsu M845A), 10 parts by weight of tricyclodecane dimethanol dimethacrylate (Shin Nakamura Chemical: NKDCP) as a polymerizable monomer, 3 parts of an aluminum coupling agent (Ajinomoto: AL-M) 0.5 parts by weight and 3.0 parts by weight of dicumyl peroxide as a radical initiator as a crosslinking agent (III) were added and dissolved in 200 parts by weight of toluene to prepare. Next, 50% by volume of aluminum nitride (Toyo Aluminum: UMK average particle size 6.5 μm) was added as a thermally conductive inorganic filler (IV) to 50% by volume of the resin composition in the solution, and the mixture was centrifuged using a centrifugal de-stirrer. By sufficiently stirring, an electrically insulating resin composition was prepared. An insulating layer having a thickness of 100 μm was formed from the obtained solution in the same manner as in Example 1, and a laminate was further produced. A laminate was produced in the same manner as in Example 2 using the obtained electrically insulating resin composition.

  The laminated board produced by Examples 1-4 and Comparative Examples 1-3 was evaluated with the following evaluation method. The results are shown in Tables 1 and 2.

<T peel strength test>
A sample having a 10 mm wide pattern formed by etching the copper foil of the laminated board is prepared, and the T peel strength (N / cm) when peeling off at a rate of 50 mm / min so that the substrate and the copper foil are vertical It was measured.

<Solder heat resistance test>
Samples were prepared according to JIS C-6481 from the laminates prepared in the above examples and comparative examples, and the sample was floated on a 300 ° C. solder bath, and the time until the presence or absence of swelling, cracks, etc. was observed visually. It was measured.

<Withstand voltage after high temperature thermal degradation>
A test pattern for a withstand voltage test (copper foil pattern having a diameter of 20 mm) was produced by etching, left in a drying oven at 220 ° C. for 120 hours, and then measured according to a step withstand voltage test method of JIS C2110.

  As shown in Tables 1 and 2, in Examples 1 to 4, the rubbery polymer compound (I) having an iodine value of 25 or less is used so that the heat resistance is excellent, and sufficient characteristics are also obtained in the copper foil T peel strength test. It is clear that the withstand voltage characteristics after high temperature degradation are very excellent, and an insulating material that is practical at high temperatures was obtained. In addition, since the electrical insulating layers in Examples 1 to 4 are more flexible than the electrical insulating layers in Comparative Examples 1 to 3, solder crack resistance in a heat cycle can be expected.

  When these results are combined, the intended tendency of the present invention can be stated as follows. That is, when a polymer having an iodine value of more than 25 is used as the rubber-like polymer compound (I), the crosslinking reaction is not sufficiently performed, that is, the unsaturated bond remains, so that the characteristics deteriorate due to oxidative degradation at a high temperature. . These degradations have an impact on most other properties. On the other hand, when an electrical insulation layer is produced with a composition according to the scope of the present invention, the crosslinking proceeds to a state in which almost no unsaturated bond that undergoes oxidative degradation remains, and an electrical insulation layer having high heat resistance can be obtained.

  As described above, the electrically insulating resin composition according to the present invention has excellent flexibility, adhesion, and moisture resistance, and has heat deterioration resistance that can withstand high heat treatment during soldering. Since it can be used stably over a long period of time even in a harsh and humid environment, it is useful as an electrical insulating material in a circuit board such as a printed wiring board. In particular, it is suitable for use in circuit boards for electrical equipment that is used under high temperature and vibration conditions, such as applications that generate a large amount of heat, such as inverters for air conditioners and industrial motors, and electrical equipment mounted in automobile engine rooms, etc. can do.

Claims (6)

A rubbery polymer (I) selected from an ethylene-α-olefin-nonconjugated diene copolymer, an isobutylene-isoprene copolymer, a halogenated butyl rubber or a vinyl aromatic compound-isobutylene-isoprene copolymer;
A cyclic aliphatic compound, an aromatic ring compound or a heterocyclic compound (II) having one or more double bonds at the terminal;
A radical polymerization initiator (III) of an organic peroxide or an azobis compound ,
And a thermally conductive inorganic filler (IV),
Before SL rubbery polymer compound with respect to 50 to 95 parts by weight of (I), the electrically insulating resin composition characterized by blending the compound (II) in a proportion of 50 to 5 parts by weight. The electrically insulating resin composition according to claim 1 , wherein the rubbery polymer compound (I) has an iodine value of 25 or less. Furthermore, the oligomer (V) of an unsaturated cycloaliphatic compound is contained,
40 to 10 parts by weight of the compound (II) and 40 to 10 parts by weight of the oligomer (V) with respect to 50 to 80 parts by weight of the rubbery polymer compound (I) The electrically insulating resin composition according to claim 1 or 2 . The electrically insulating resin composition by being cured after being formed into a layer on a metal substrate, among claim 1, characterized in that the electrically insulating layer of a circuit board according to claim 3, or 2. The electrically insulating resin composition according to item 1. 5. A circuit board comprising a metal layer on at least one surface of an electrical insulating layer obtained by curing the electrical insulating resin composition according to any one of claims 1 to 4 . Laminated body. Wherein the metal layer is formed on both sides of the electrically insulating layer, wherein a metal substrate a metal layer of one of the metal layers, claim other metal layer, characterized in that a metal foil for wiring formation 5 The laminated body for circuit boards as described in 2.