JP4447956B2 - Electrical insulating resin composition, and sheet-like uncured product using the same, uncured laminate for circuit board, and cured laminate for circuit board - Google Patents

Description

  The present invention is 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 sheet-like uncured product using the same, an uncured laminate for a circuit board, More particularly, the present invention relates to an electrically insulating resin composition capable of forming an electrically insulating layer having both excellent flexibility and high heat resistance. More specifically, it is an electrically insulating resin composition suitable for use on a metal base substrate with excellent heat dissipation, excellent solder heat resistance, and can be used stably over a long period of time even in harsh environments of high temperature and high humidity. The present invention relates to an electrically insulating resin composition capable of forming an electrically insulating layer.

  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 part of a component is desired.

  As a circuit board used in such a harsh environment, a metal base board in which an electrically insulating layer is provided on a metal base material 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 substrate, epoxy resin is often used as an electrical insulating layer. However, since the epoxy resin itself has low thermal conductivity, heat generated by the conductive circuit can be efficiently transferred to the metal substrate. 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 electric insulating layer is lowered and becomes brittle, and the adhesion of the electric insulating layer to the metal substrate is also reduced. . In addition, when soldering to a metal base substrate, the treatment is performed at a high temperature of 200 ° C. or higher. However, if the blending ratio of the inorganic filler is high, a crack is generated in the electrical insulating layer due to high heat during soldering, and the withstand voltage is improved. It was also a factor of decline.

For this reason, Patent Document 1 discloses a metal base substrate 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 adhesiveness 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 using such a low elastic modulus epoxy resin, the created circuit has electrical and physical characteristics such as ion migration resistance and water absorption. It was inevitable that there was a decline.

  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 elastic modulus heat 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 improves the handleability by making the resin semi-cured (B stage state) so that it does not stick even when touched by hand at room temperature. . However, the epoxy-cured insulating adhesive layer material has a short material life in the B-stage state, and has many problems such as management and storage. In addition, 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 highly filled.

  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 extremely 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, substrate adhesion, high heat resistance, moisture resistance, withstands high heat treatment during soldering, An electrically insulating resin composition capable of forming an electrically insulating layer that can be used stably over a long period of time even in a severe environment of vibration, and a sheet-like uncured product and an uncured laminate for a circuit board using the same And a cured laminate for a circuit board.

  In order to solve the above-mentioned problems, the present inventors have intensively studied and, as a result, at least a rubber-like polymer compound (A) comprising a copolymer of a vinyl aromatic compound and a conjugated diene compound, and one at the end. An electrically insulating resin composition comprising the polymerizable monomer (B) having the reactive double bond and the oligomer (C) having a cyclic structure in the molecule and having a reactive unsaturated bond. It is found that an electrical insulating layer having excellent flexibility, adhesion, moisture resistance, and heat deterioration resistance can be formed by blending so that the D hardness after curing of the organic component contained in the composition is 75 or less. The present invention has been achieved.

  The electrically insulating resin composition of the present invention can be polymerized utilizing radical polymerization reaction, thermal polymerization reaction, etc., and the resulting reaction product is a uniform cross-link between the rubbery polymer compound and the polymerizable monomer. It becomes the structure. In the conventional electrically insulating resin composition to which no oligomer component is added, when the polymerizable monomer undergoes a polymerization reaction in the rubbery polymer compound, the polymer of the polymerizable monomer grows into particles, and the rubbery polymer compound In some cases, a polymer of a polymerizable monomer is present in a discontinuous phase in the continuous phase, which is a heterogeneous system. In contrast, in the present invention, by adding an oligomer component, the cured product obtained has a structure in which the oligomer functions as a compatibilizer for the rubbery polymer compound and the polymerizable monomer, and the three components are more uniformly polymerized. Therefore, local heating loss at high temperature does not occur, and therefore microvoids do not occur in the insulating layer, or the withstand voltage characteristics after thermal deterioration can be further improved, and heat resistance is required. It can use suitably for a use etc.

  In the present invention, it is preferable to further include a thermally conductive inorganic filler in the electrically insulating resin composition.

  The sheet-like uncured material of the present invention is an uncured sheet-like material used for forming an electrical insulating layer on a circuit board. As the sheet-like uncured material of the present invention, the electrically insulating resin composition of the present invention is formed on a prepreg sheet obtained by impregnating a fiber sheet with the electrically insulating resin composition of the present invention or a peelable film. An adhesive sheet formed with an uncured electrical insulating layer formed from a product can be mentioned. The prepreg sheet of the present invention is a sheet-like uncured material that is cured after being laid on a metal layer (metal conductor foil or metal substrate for a wiring layer), and the adhesive sheet of the present invention is In the sheet-like uncured material, after peeling off the peelable film from the uncured electrical insulating layer, the uncured electrical insulating layer is transferred onto the metal layer and cured to become an electrical insulating layer. is there.

  Furthermore, the uncured laminate of the present invention is a laminate used for the production of a circuit board, and comprises an uncured electrical insulating layer obtained from the electrical insulating resin composition of the present invention, a metal layer (wiring layer) Metal conductor foil or metal substrate). That is, the uncured laminate of the present invention is used for simultaneously forming an electrical insulating layer and one layer selected from a metal substrate or a metal conductor foil for a wiring layer. As an uncured laminate of the present invention, a laminate having a two-layer structure in which an uncured electrical insulating layer obtained from the electrical insulating resin composition of the present invention is formed on a metal plate serving as a metal substrate, or A laminate having a two-layer structure in which an uncured electric insulating layer obtained from the electric insulating resin composition of the present invention is formed on a metal conductor foil to be a wiring layer can be exemplified.

  The cured laminate of the present invention is a laminate used for the production of a circuit board, and a metal layer (wiring layer) is formed on at least one surface of an electrical insulating layer obtained by curing an electrical insulating resin composition. Metal conductor foil or metal substrate). The cured laminate of the present invention has a three-layer cured laminate formed by laminating a metal substrate, an electric insulating layer and a metal conductor foil in this order, and a two-layer structure obtained by laminating a metal conductor foil and an electric insulating layer in this order. And a cured laminate 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. A cured laminate 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 substrate. In addition, a cured laminate having a two-layer structure in which metal conductor foil and an electrical insulating layer are laminated in order, and a cured laminate having a three-layer structure in which metal conductor foil, an electrical insulating layer and a metal conductor foil are laminated in order, As a normal printed wiring board material, it is used for a single-sided circuit board, a double-sided circuit board, an inner layer circuit of a multilayer circuit board, and the like.

  The electrically insulating resin composition of the present invention is a compound having an unsaturated double bond capable of radical polymerization reaction or thermal polymerization reaction, and is compatible with each other: rubbery polymer compound, oligomer, polymerizable monomer. Since the components are used, the resulting cured product has a tissue structure in which the three components of the rubbery polymer compound, the oligomer, and the polymerizable monomer are uniformly polymerized. For this reason, the heat deterioration lifetime can be improved, and it can be suitably used for applications requiring heat resistance.

In addition, by using a rubbery polymer compound, it is possible to obtain an electrically insulating material with good workability while maintaining flexibility even when filled with a heat conductive inorganic filler such as alumina in order to improve heat dissipation. Further, by 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.

  In addition, by adding a solid oligomer at room temperature, the tackiness can be suppressed, and there is also an effect that workability is improved without stickiness in the production of an uncured laminate.

  In addition, since a radical polymerization reaction or a thermal 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. Moreover, the curing time during the production of the cured laminate can be shortened, which is useful for improving productivity and saving energy.

[I] Electrical Insulating Resin Composition The electrical insulating resin composition of the present invention is an electrical insulating resin composition containing an organic component having a D hardness after curing of 75 or less. , A rubbery polymer compound (A), a polymerizable monomer (B), and an oligomer (C).

  As the rubbery polymer compound (A), a copolymer of a vinyl aromatic compound (i) and a conjugated diene compound (ii) is used.

  Specific examples of the vinyl aromatic compound that is the monomer component of (i) include styrene, α-methylstyrene, p-methylstyrene, vinylpyridine, t-butylstyrene, N, N-diethyl-p-aminoethylstyrene, Examples include divinylbenzene.

  Specific examples of the conjugated diene that is the monomer component of (ii) include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2- Examples include methyl-1,3-pentadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like.

  The copolymer used as the rubbery polymer compound may be either a block copolymer or a random copolymer. In the case of a block copolymer, when the polymer block derived from the monomer component (i) is A and the polymer block derived from the monomer component (ii) is B, it is represented by A-B-A or A-B. Examples thereof include block copolymers.

In the copolymer, when the total of the monomer component (i) and the monomer component (ii) is 100% by weight, the proportion of the monomer component (i) is preferably less than 50% by weight, and more preferably Is preferably 10 wt% to 30 wt%. By setting the proportion of the monomer component (i) to less than 50% by weight, the elastic modulus, flexibility, and heat resistance can be secured, and the adhesion to the metal layer is improved. The polymerization form of the conjugated diene is 1, 4-bond is enhanced preferred flexibility of the cured product obtained with the structure of the principal. When the 1,2-vinyl bond increases, the rubbery properties are deteriorated and the hardness increases, which is not preferable.

  In addition, modified products obtained by introducing 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 into the above copolymer are also available. The rubbery polymer compound (A) in the present invention can be used. It is preferable to introduce a bond such as a polar group, a urethane bond, an ester bond, or an amide bond into the copolymer so that the adhesion to the metal layer can be improved.

  A partially hydrogenated polymer obtained by partially hydrogenating the above copolymer can also be used as the rubbery polymer compound (A) in the present invention. The unsaturated portion remaining unreacted after the monomer component (ii) is polymerized may cause cracks due to high heat during soldering, but the unreacted component derived from the monomer component (ii). It is effective for further improving the heat resistance to hydrogenate the saturated group in advance while leaving a part of it. In this case, the hydrogenation rate of the rubber-like polymer compound (A) is 70% or more, preferably 80% to 99%.

  The molecular weight Mw of the rubbery polymer compound (A) used in the present invention is preferably 30,000 to 300,000. More preferably, the molecular weight is 50,000 to 150,000.

  In the present invention, the rubbery polymer compound may be used alone, but two or more rubbery polymer compounds having different monomer composition ratios or different molecular weights may be used in combination. It is preferable to use two or more rubbery polymer compounds in combination since the compatibility, adhesiveness, flexibility and the like of the electrically insulating resin composition can be adjusted accordingly.

  As the polymerizable monomer (B), a polymerizable monomer having one or more reactive double bonds at the terminal is used. The polymerizable monomer is a compound having one or more reactive double bonds at the terminal portion in the molecule, and a compound that can be cured by radical polymerization or thermal polymerization is used. As such a compound, for example, a compound having a double bond exhibiting high reactivity such as vinyl, allyl, methallyl, methacryl, and acrylic at the terminal, a conjugated diene, a non-conjugated diene, or the like can be used.

  Specific examples of such polymerizable monomers include divinyl heptane, divinyl octane, divinyl nonane, vinyl benzene, divinyl benzene, bisphenol A type epoxy acrylate, methyl methacrylate, isobornyl acrylate, tricyclodecane dimethacrylate, triallyl isocyanurate. Examples thereof include ethoxylated isocyanuric acid triacrylate, butadiene, isobutylene, pentadiene, hexadiene, octadiene, nonadiene, decadiene, dicyclopentadiene, and ethylidene norbornene. 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, compatibility and heat resistance can be further improved.

  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 above-described polymerizable monomer, Since adhesiveness can be improved, it is preferable.

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

  Since the polymerizable monomer mainly relates 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.

  As the oligomer (C), an oligomer having a cyclic structure in the molecule and having a reactive unsaturated bond is used. By blending an oligomer having a cyclic structure in the molecule and having a reactive unsaturated bond, the oligomer acts as a compatibilizer for the rubbery polymer compound and the polymerizable monomer, so that the compatibility of the mixture is increased. The homogeneity of the curing reaction is increased and the heat resistance of the cured product can be improved.

  As the oligomer, a compound having a cyclic structure such as aromatic, cycloaliphatic or heterocyclic in the molecule is used. Examples of the cyclic skeleton contained in the oligomer molecule include coumarone, indene, rosin, cyclopentane, cyclohexane, 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 are more compatible than aromatic and heterocyclic oligomers. This is preferable because the action is high and the heat resistance of the cured product can be further improved.

  The oligomer used in the present invention is a polymer of a polymerizable monomer having a cyclic structure, a copolymer of a polymerizable monomer having a cyclic structure and an aliphatic unsaturated compound, or an ester compound thereof. Can do.

  Specific examples of compounds include (1) 5-ethylidene-2-norbornene and dicyclopentadiene, which are cycloaliphatic compounds, or styrene and vinyltoluene, which are aromatic vinyl compounds, and aliphatic unsaturated compounds. A copolymer with 1,4-hexadiene, isobutylene, 1,3-pentadiene and the like, (2) a condensation polymer such as a rosin derivative or an esterified product thereof, (3) a dimer acid or a modified product, (4) A copolymer such as a coumarone indene resin, a polymer of (5) triallyl isocyanurate, and the like can be exemplified, and among these, the compounds (1) to (3) are more preferable.

  The oligomer needs to have one or more reactive unsaturated bonds in the molecule. By using an oligomer having 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 above-mentioned oligomer, it is possible to improve adhesion to metals. Can be improved.

  The molecular weight Mw of the oligomer is preferably 300 to 10,000, and more preferably 400 to 1,000. By using an oligomer having a molecular weight corresponding to an intermediate molecular weight between the rubbery polymer compound and the polymerizable monomer, the compatibility of the electrically insulating resin composition can be further enhanced.

  From the viewpoint of quality stability that lowers the tackiness of the uncured product of the electrically insulating resin composition, it is preferable to use an oligomer that is solid at room temperature.

  In this invention, each organic component is mix | blended so that D hardness after hardening of the organic component in an electrically insulating resin composition may be 75 or less. “D hardness” means a value measured according to a JIS test method. In addition, the “organic component” referred to here includes all organic compounds contained in the electrically insulating resin composition, and includes the components (A), (B), and (C) described above. , Polymerization initiators described later, various additives, and the like are included.

  In the present invention, by setting the D hardness after curing of the organic component to 75 or less, it is possible to form an electrical insulating layer having excellent flexibility, adhesion, moisture resistance, and heat deterioration resistance. When the D hardness after curing of the organic component exceeds 75, the flexibility and the adhesion to the metal layer are insufficient, and when the inorganic filler is highly filled, the electrical insulating layer cracks due to high heat, There is a problem that the voltage property is lowered. In the present invention, it is more preferable that the D hardness after the organic component is heated and pressurized and cured is 70 or less.

  The blending ratio of the above component (A), component (B), and component (C) is not particularly limited as long as the D hardness after curing of the organic component is 75 or less. Since the preferred blending ratio varies depending on the type of organic component, it is difficult to define it generally. However, in order to adjust the D hardness to 75 or less, it is preferable to blend the component (A) as a main component. Specifically, when the total of the three components is 100% by mass, the component (A) is preferably blended in a proportion of 50% by mass or more. In particular, the component (A) is preferably contained in an amount of 50 to 80% by mass, the component (B) in an amount of 40 to 10% by mass, and the oligomer component in an amount of 40 to 10% by mass.

  In the electrically insulating resin composition of the present invention, it is preferable to add a thermally conductive inorganic filler in order to improve thermal conductivity. Examples of the thermally conductive inorganic filler 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 can be determined and blended. The blending amount of the heat conductive inorganic filler is 40% to 90%, preferably 50% to 75% in terms of volume fraction with respect to the volume of the electrically insulating resin composition (including the heat conductive inorganic filler). Blend in.

  The electrically insulating resin composition of the present invention can be cured by a radical polymerization reaction or a thermal polymerization reaction, and any reaction method can be adopted, but it is preferably cured by a radical polymerization reaction. Add polymerization initiator.

  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 thereof include, but are not limited to, acid, t-butyl peroxide, dicumyl peroxide, azobisisobutyronitrile and azobis-1-cyclohexanenitrile which are azobis compounds.

  The addition amount of the radical polymerization initiator is 0.1 to 10 parts by weight with respect to 100 parts by weight in total of the components (A), (B) and (C), and is in the range of 1 to 5 parts by weight. Addition is preferable because a good cured product can be obtained.

  In addition, the inorganic material may be surface-treated with a silane coupling agent exemplified by epoxy silane, amino silane, methacryloxy silane, or titanate or aluminum coupling agent in advance, or in an electrically insulating resin composition. By mix | blending, the adhesive force with resin compositions, such as a heat conductive inorganic filler, glass cloth, and copper foil, 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 fluidity of the electrically insulating resin composition In order to adjust this, the electrically insulating resin composition of the present invention may be diluted using an organic solvent. Examples of the organic solvent include methanol, ethanol, propanol, isopropanol, methyl acetate, ethyl acetate, benzene, toluene, xylene, acetone, methyl ethyl ketone, diethyl ether, dioxane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, chlorobenzene and the like. Of these, one or more of them are appropriately selected and used.

  In addition, various additives may be added. As the additive, for example, an ion adsorbent for suppressing ion migration and an anti-aging agent for preventing oxidative degradation can be used. Moreover, a flame retardant can also be added and flame retardance can also be raised.

  By electrically mixing the components described above, the electrically insulating resin composition of the present invention can be prepared.

[II] Cured laminate for circuit board and forming material thereof The electrically insulating resin composition of the present invention can be used without limitation as an electrically insulating material in a known circuit board, but particularly in a metal base substrate. Since it can be suitably used as an electrically insulating material, the following description will focus on a metal base substrate.

  The metal base substrate of the present invention is a cured laminate obtained by laminating a metal base material, an electrical insulation layer and a metal conductor foil in this order, and the electrical insulation layer is made of a cured product of the electrical insulation resin composition of the present invention. It is characterized by that. In its use, a circuit board can be formed by subjecting the surface metal conductor foil to a general circuit forming process such as an etching process. Moreover, it is good also as a multilayer circuit board by forming an electrical insulation layer and metal conductor foil further on the circuit formation surface of the said circuit board, and also giving circuit formation processing to the surface metal conductor foil.

  The electrical insulating layer is obtained by thermally curing the electrical insulating resin composition of the present invention by a radical polymerization reaction or a thermal polymerization reaction. A preferable curing temperature condition is 120 to 250 ° C.

  The method for forming the metal base substrate of the present invention is not particularly limited. For example, an electrically insulating resin composition is directly applied on a metal substrate, and a metal conductor foil is applied on the coating film of the electrically insulating resin composition. To heat and pressure cure the electrically insulating resin composition, or directly apply the electrically insulating resin composition on the metal conductor foil, and then apply the electrically insulating resin composition on the coating film of the electrically insulating resin composition. It can form by arrange | positioning a metal base material and heat-press-hardening an electrically insulating resin composition. 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 insulation layer, and the peelable film is peeled off from the uncured electrical insulation layer to form a metal substrate and a metal conductor foil. An uncured electrical insulating layer may be disposed between the layers, and the uncured electrical insulating 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 laminate for circuit boards as described below. For example, you may use as a hardening laminated body for circuit boards which provides a 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.

  When producing a cured 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 with one side of the above-described prepreg sheet or adhesive sheet, and heat-cured with a hot press or the like. Can be manufactured. Moreover, it can manufacture also by forming a coating film (uncured electrical insulation layer) on a metal conductor foil using an electrical insulating resin composition, and heat-curing this.

  When producing a cured laminate for a double-sided circuit board in which metal conductor foils are provided on both sides of the electrical insulation layer, the metal conductor foils are disposed on both sides of the above-described prepreg sheet or adhesive sheet, or uncured laminates. In the case of a body, it is 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, and particularly preferably in the range of 50 to 150 μm.

  As the metal substrate, metal materials such as aluminum and 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. The metal conductor foil has a thickness of 5 to 500 μm, preferably 35 to 300 μm.

  Next, a forming material for forming the cured laminate for a circuit board of the present invention will be described. As a main supply form of the forming material for forming the cured laminate for a circuit board of the present invention, (1) a sheet-like uncured material used for forming an electrical insulating layer in a circuit board, and ( 2) In a circuit board, an uncured laminate having a two-layer structure for forming an electrical insulating layer and one layer selected from a metal substrate or a metal conductor foil for a wiring layer may be mentioned. In addition, although these formation materials can be utilized suitably for manufacture of a metal base board | substrate, the use is not limited to this.

  As the sheet-like uncured material of (1), an adhesive sheet in which an electrically insulative resin composition is applied to (i) a prepreg sheet and (ii) a peelable film to form an uncured electrically insulating layer. 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 overlapped 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 base material is arranged on the other side. By heat-pressing the laminate, 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 metal conductor foils are stacked on both sides of a prepreg sheet and the electrically insulating resin composition is cured can be used for an inner layer circuit of a multilayer circuit board.

  As the fiber sheet used for preparing the prepreg sheet, an organic or inorganic woven fabric or nonwoven fabric can be used. As the inorganic fiber sheet, glass cloth, glass nonwoven fabric, alumina cloth or the like can be used. Moreover, as an organic fiber sheet, fiber sheets, such as a cloth | cross and a nonwoven fabric which consist of polyamide, a polyimide, an aramid, heat resistant polyester, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), carbon fiber etc., can be used.

  The prepreg sheet can be formed by diluting the electrically insulating resin composition of the present invention to an appropriate concentration with an organic solvent and the like, impregnating it with 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 substrate. Furthermore, it can be used as a cured laminate for an inner layer circuit in a multilayer circuit board by thermocompression bonding with a metal conductor foil superimposed on one or both sides.

  This adhesive sheet can be obtained, for example, by applying the electrically insulating resin composition of the present invention onto 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. The film preferably has a thickness of 10 to 200 μm, more preferably 30 to 100 μm.

  Moreover, as the uncured laminate of (2), (i) a laminate having a two-layer structure in which an uncured electrical insulating layer obtained from the electrical insulating resin composition of the present invention is formed on a metal substrate, Alternatively, (ii) a two-layer structure laminate in which an uncured electrical insulating layer obtained from the electrical insulating resin composition of the present invention is formed on a metal conductor foil to be a wiring layer can be mentioned. When producing such an uncured laminate, it is 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. Can do.

  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 made of metal by heating and pressing with the uncured electrical insulation layer placed on the metal substrate. By sticking to a base material, the 3 layer laminated body which consists of a metal base material, an electric insulation layer, and metal conductor foil is formed. Moreover, it can utilize as a hardening laminated body for the inner layer circuits in a multilayer circuit board by carrying out the 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 of metal by heating and pressing with the metal conductor foil placed on the uncured electrical insulation layer. By sticking on the conductor foil, a three-layer laminate formed by laminating the metal base, the electrical insulating layer, and the metal conductor foil in this order is formed.

  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 peeled off during use. As the protective film, the above-described peelable film or the like is used.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

Example 1
To 130 parts by weight of toluene, epoxy-modified SBS block copolymer A (styrene / butadiene = 40/60, oxirane oxygen concentration 1.5 wt%, molecular weight of about 100,000, MFR 7 g / 10 min (190 ° C.) as a rubbery polymer compound 2.16 kgf)) 60 parts by weight, 20 parts by weight of dicyclopentadiene petroleum resin (iodine number = 190, softening point = 145 ° C.) as oligomer C and 20 parts by weight of tricyclodecane dimethanol dimethacrylate as monomer E Then, 2.7 parts by weight of an acrylic silane coupling agent and 3.0 parts by weight of a radical initiator (dicumyl peroxide) were added to knead the electrically insulating resin composition.

  The obtained electrically insulating resin composition was applied to one side 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 electric insulating layer coated on a copper foil is overlaid on an aluminum substrate having a thickness of 1.0 mm, and heat-pressed and cured at 180 ° C. and 5 MPa for 30 minutes with a hot press, and the aluminum substrate, the electric insulating layer, A cured laminate composed of three layers of copper foil was prepared.

(Example 2)
The electrically insulating resin was the same as in Example 1 except that the addition amount of the rubbery polymer compound A was 70 parts by weight, the addition amount of the oligomer C was 10 parts by weight, and the addition amount of the monomer E was 20 parts by weight. A composition was prepared. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer, and a copper foil was prepared in the same manner as in Example 1.

(Comparative Example 1)
The electrically insulating resin was the same as in Example 1 except that the amount of the rubbery polymer compound A added was 40 parts by weight, the amount of the oligomer C added was 30 parts by weight, and the amount of the monomer E added was 30 parts by weight. A composition was prepared. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

  The cured laminates of Examples 1 and 2 and Comparative Example 1 (without inorganic filler) were evaluated by the following evaluation methods. The results are shown in Table 1.

<D hardness>
Measure D hardness of electrical insulation layer after heat and pressure curing according to JIS test method using durometer type D (Ueshima Seisakusho Co., Ltd.) specified in JIS K7215 “Plastic Durometer Hardness Test Method”. did.

<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. Moreover, T peel strength was measured about the high temperature deterioration sample which put the sample in 220 degreeC oven for five days and made high temperature deterioration. The retention rate was calculated from the T peel strength after high temperature degradation and the T peel strength of the A state (the state before the deterioration treatment).
Retention rate (%) = (T peel strength after high temperature degradation / T peel strength in A state) × 100

<Solder heat resistance test>
A sample was prepared by removing the copper foil for 25 × 50 mm of the 50 × 50 mm laminated plate, and the sample was floated on a solder bath at 300 ° C., and the time until the presence or absence of swelling was observed by visual observation was measured. .

Ａ：エポキシ変性ＳＢＳブロック共重合体
Ｃ：ジシクロペンタジエン系石油樹脂
Ｅ：トリシクロデカンジメタノールジメタクリレート

A: Epoxy-modified SBS block copolymer C: Dicyclopentadiene petroleum resin E: Tricyclodecane dimethanol dimethacrylate

  As shown in Table 1, the electrical insulation layer of Comparative Example 1 has a D hardness of more than 75 and does not satisfy the flexibility standard required for the present invention. For this reason, the adhesiveness to a board | substrate is inferior compared with Example 1 and 2 evidently from a T peel strength test. Moreover, as shown in the solder heat test, the heat resistance is also poor. From this result, it can be seen that in the electrically insulating resin composition of the present invention, it is an important condition that the organic component is blended so that the D hardness after curing is 75 or less.

(Example 3)
To 130 parts by weight of toluene, epoxy-modified SBS block copolymer A (styrene / butadiene = 40/60, oxirane oxygen concentration 1.5 wt%, molecular weight of about 100,000, MFR 7 g / 10 min (190 ° C.) as a rubbery polymer compound 2.16 kgf)) 50 parts by weight, 5 parts by weight of dicyclopentadiene petroleum resin (iodine number = 190, softening point = 145 ° C.) as oligomer C, 45 parts by weight of tricyclodecane dimethanol dimethacrylate as monomer E Then, 2.7 parts by weight of an acrylic silane coupling agent and 3.0 parts by weight of a radical initiator (dicumyl peroxide) were added to knead the organic components. Next, 60% by volume of a thermally conductive inorganic filler (alumina, average particle size 10 μm, BET specific surface area 2.0 m ² / g) is added to 40% by volume of the organic component, and the mixture is stirred for 5 minutes with a centrifugal defoaming stirrer. Thus, an electrically insulating resin composition was prepared.

  Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

Example 4
When preparing the organic component, Example 3 and Example 3 except that the addition amount of the rubber-like polymer compound A was 60 parts by weight, the addition amount of the oligomer C was 20 parts by weight, and the addition amount of the monomer E was 20 parts by weight. Similarly, an electrically insulating resin composition was prepared. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

(Example 5)
When preparing an organic component, SBS block copolymer B (styrene / 1,4-butadiene = 30/70, molecular weight 120,000, MFR 6 g / 10 min (200 ° C., 49.0 N)) is used as a rubbery polymer compound. An electrically insulating resin composition was prepared in the same manner as in Example 4 except that it was used. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

(Example 6)
When preparing the organic component, the same as Example 3 except that the addition amount of the rubbery polymer compound A was 70 parts by weight, the addition amount of the oligomer C was 15 parts by weight, and the addition amount of the monomer E was 15 parts by weight. Thus, an electrically insulating resin composition was prepared. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

(Example 7)
In preparing the organic component, instead of the oligomer C, the oligomer D (copolymer petroleum resin of cyclopentadiene, C5 component and C9 component, bromine number = 50, softening point = 60 ° C., average molecular weight = 800) was used. Except for this, an electrically insulating resin composition was prepared in the same manner as in Example 4. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

(Comparative Example 2)
With respect to 130 parts by weight of toluene, an epoxy-modified SBS block copolymer (styrene / butadiene = 40/60, oxirane oxygen concentration 1.5 wt%, molecular weight of about 100,000, MFR 7 g / 10 min (190 ° C.) as rubbery polymer compound A )) 50 parts by weight, after dissolving 50 parts by weight of tricyclodecane dimethanol dimethacrylate as monomer E, 2.7 parts by weight of acrylic silane coupling agent and 3.0 parts by weight of radical initiator (dicumyl peroxide) Part was added and the organic component was kneaded. Next, 60% by volume of a thermally conductive inorganic filler (alumina, average particle size 10 μm, BET specific surface area 2.0 m ² / g) is added to 40% by volume of the organic component, and the mixture is stirred for 5 minutes with a centrifugal defoaming stirrer. Thus, an electrically insulating resin composition was prepared.

  Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

(Comparative Example 3)
When preparing the organic component, an electrically insulating resin composition was prepared in the same manner as in Comparative Example 2 except that the addition amount of the rubber-like polymer compound A was 70 parts by weight and the addition amount of the monomer E was 30 parts by weight. did. Using the obtained electrically insulating resin composition, a cured laminate composed of three layers of an aluminum substrate, an electrically insulating layer and a copper foil was prepared in the same manner as in Example 1.

  The cured laminates of Examples 3 to 7 and Comparative Examples 2 and 3 (with inorganic filler) were subjected to a T peel strength test and a solder test in the same manner as in Examples 1, 2 and Comparative Example 1, and the following evaluations were made. The withstand voltage test was performed by the method. The evaluation results are shown in Table 2.

<anti-voltage test>
A sample in which a copper foil land having a diameter of 20 mm was formed by etching the copper foil of the laminate was prepared. Further, the sample was put in an oven at 220 ° C. for 5 days to prepare a high temperature deteriorated sample, and the sample was floated in a solder bath at 300 ° C. for 2 minutes to prepare a solder deteriorated sample. The withstand voltage was measured for the A state (the state before the deterioration treatment), the high temperature deterioration, and the solder deterioration. Withstand voltage measurement was started from 1 kV, boosted by 500 V every 20 seconds, and the value obtained by subtracting 500 V from the voltage causing dielectric breakdown was taken as the withstand voltage value.

Ａ：エポキシ変性ＳＢＳブロック共重合体
Ｂ：ＳＢＳブロック共重合体（エポキシ変性なし）
Ｃ：ジシクロペンタジエン系石油樹脂
Ｄ：シクロペンタジエンとＣ５、Ｃ９成分との共重合体系石油樹脂
Ｅ：トリシクロデカンジメタノールジメタクリレート

A: Epoxy-modified SBS block copolymer B: SBS block copolymer (no epoxy modification)
C: Dicyclopentadiene-based petroleum resin D: Copolymer-based petroleum resin of cyclopentadiene and C5 and C9 components E: Tricyclodecane dimethanol dimethacrylate

  As is clear from the T peel strength test, it can be seen that in Examples 3 to 7, even when the high temperature deterioration treatment was performed, the T peel strength hardly decreased and the adhesion of the electrical insulating layer to the substrate was high. On the other hand, in Comparative Examples 2 and 3, since no oligomer is contained, the adhesiveness of the electrical insulating layer to the substrate is lowered by the high temperature deterioration treatment.

  In Examples 3 to 7, even when the high temperature deterioration treatment and the solder deterioration treatment are performed, the withstand voltage is hardly lowered and high insulation reliability is shown. On the other hand, in Comparative Examples 2 and 3, the withstand voltage was remarkably lowered after the solder deterioration treatment. In addition, due to the high temperature deterioration treatment, dielectric breakdown occurred before the withstand voltage measurement, and measurement was impossible.

  As described above, the electrically insulating resin composition according to the present invention has excellent flexibility, adhesion, moisture resistance, and has heat deterioration resistance that can withstand high heat treatment when soldering parts. It can be used stably over a long period of time even in harsh environments of high temperature and high humidity, so it is useful as an electrical insulation material for circuit boards such as printed wiring boards. Especially, it generates large amounts of heat such as air conditioners and inverters for industrial motors. It can be suitably used for a circuit board of an electronic device used under high temperature and vibration conditions, such as an electronic device mounted in an application or an automobile engine room.

Claims (6)

An electrically insulating resin composition comprising an organic component having a D hardness after curing of 75 or less,
The organic component is a rubber-like polymer compound (A) having a weight average molecular weight of 30,000 to 300,000 comprising a copolymer of a vinyl aromatic compound and a conjugated diene compound, and one or more reactive compounds at the end. It contains a polymerizable monomer (B) having a molecular weight of 100 to 350 having a heavy bond, and an oligomer (C) having a weight average molecular weight of 400 to 1000 having an alicyclic structure in the molecule and a reactive unsaturated bond. An electrically insulating resin composition characterized by that.   The content of the rubbery polymer compound (A) is 50 to 80% by mass with respect to the total amount of 100% by mass of the rubbery polymer compound (A), the polymerizable monomer (B), and the oligomer (C). 2. The electrically insulating resin composition according to claim 1, wherein the content of the conductive monomer (B) is 40 to 10 mass% and the content of the oligomer (C) is 40 to 10 mass%.   Furthermore, 40-90 volume% of heat conductive inorganic fillers are contained with respect to 100 volume% of compositions, The electrically insulating resin composition of Claim 1 or 2 characterized by the above-mentioned. It is a sheet-like uncured material that is cured after being laid on a metal layer to become an electrically insulating layer,
A sheet-like uncured product obtained by impregnating a fiber sheet with the electrically insulating resin composition according to claim 1. An uncured electrical insulation layer is formed on a peelable film, and the uncured electrical insulation layer is a sheet-like uncured material that becomes an electrical insulation layer by being cured after being transferred onto a metal layer. And
The sheet-shaped uncured product, wherein the uncured electrical insulation layer is formed from the electrical insulating resin composition according to any one of claims 1 to 3.   A cured laminate for 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 3.