Resin compositions, sheets, metal-based substrates

Abstract

The objective is to provide resin compositions, varnishes, inorganic composite sheets thereof, and metal-based substrates that contribute to improved flexibility and heat resistance. [Solution] A resin composition is provided comprising (A) a polyfunctional unsaturated imide resin, (B) synthetic rubber, (C) an initiator, and (D-1) a first inorganic filler, wherein the (D-1) first inorganic filler is boron nitride with an average particle size of 10 to 80 μm.

Description

Technical Field

[0001] The present invention relates to a resin composition, a sheet, and a metal base substrate.

Background Art

[0002] In recent years, with the demands for miniaturization, high frequency, and high output of electronic devices, in order to achieve high integration of semiconductors and miniaturization of printed wiring boards, the manufacture of printed wiring boards by the build-up method has been actively carried out. These printed wiring boards are required to have high heat dissipation performance, and the development of materials with excellent thermal conductivity is in progress.

[0003] For example, Patent Document 1 discloses an epoxy resin composition containing an epoxy resin monomer, a curing agent, and a filler, wherein the filler includes a first filler containing boron nitride particles having a D50 of 20 μm or more and an average aspect ratio of primary particles of 30 or less, or an aggregate of the boron nitride particles, and a second filler containing boron nitride particles having a D50 of less than 10 μm and an average aspect ratio of 5 or less, or an aggregate of the boron nitride particles.

[0004] Patent Document 2 discloses an epoxy resin composition containing an epoxy resin monomer, a curing agent containing a novolak resin obtained by novolakizing a divalent phenol compound, and a mixed filler of α-alumina and boron nitride.

[0005] However, in order to cure the B stage of these resin compositions, it is required to thermally press the laminate from both sides to promote the addition reaction, but the reaction time is long and the molding cycle is long, which is a problem. In addition, there is a possibility that the inorganic filler in the resin composition is crushed by pressing and cannot exhibit its original thermal conductivity.

[0006] Therefore, various resin compositions using bismaleimide resins, in which an improvement in production efficiency is expected in a radical polymerization system, have been developed (Patent Documents 3 to 4).

Prior Art Documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-165401 [Patent Document 2] Japanese Patent Publication No. 2016-155985 [Patent Document 3] Japanese Patent Publication No. 2021-38318 [Patent Document 4] Japanese Patent Publication No. 2020-173945 [Patent Document 5] Patent No. 7330648 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, for example, the resin composition in Patent Document 3 had low thermal conductivity even in the system containing boron nitride, and there was room for improvement from the viewpoint of film flexibility. Similarly, Patent Document 4 could not be made into a thin film and was not satisfactory from the viewpoint of flexibility.

[0009] Furthermore, the maleimide resin described in Patent Document 5 is a polymer resin with a number average molecular weight of 3,000 or more, and has low heat resistance. There were also no examples containing inorganic fillers, and the study of its application to printed circuit boards and the like was insufficient.

[0010] Based on the above, the present invention aims to provide a resin composition, a varnish, an inorganic composite sheet thereof, and a metal-based substrate that contribute to improved flexibility and heat resistance. [Means for solving the problem]

[0011] The inventors diligently conducted research to solve the above problems. As a result, they found that a resin composition containing a polyfunctional unsaturated imide resin, synthetic rubber, and a specific inorganic filler exhibits excellent flexibility, heat resistance, and improved sheet handling properties.

[0012] In other words, the present invention includes the following embodiments.

[0013] [1] (A) a polyfunctional unsaturated imide resin, (B) synthetic rubber, (C) an initiator, and (D-1) a first inorganic filler, A resin composition characterized in that the (D-1) first inorganic filler is boron nitride with an average particle size of 10 to 80 μm.

[0014] [2] The resin composition according to [1] above, wherein the polyfunctional unsaturated imide resin (A) is represented by the following general formula (1).

[0015] [ka] (In the formula, Z represents a divalent group containing a carbon-carbon double bond, R 1 (where k represents an organic group with two or more functions, and k is an integer greater than or equal to 2.)

[0016] [3] The resin composition according to [1] or [2] above, wherein the synthetic rubber (B) is at least one selected from the group consisting of 1,2-polybutadiene, 1,4-polybutadiene, styrene-butadiene, malee-modified 1,2-polybutadiene, acrylic-modified 1,2-polybutadiene, styrene-ethylenepropylene, epoxy-modified 1,2-polybutadiene, and rubbers.

[0017] [4] The resin composition according to any one of [1] to [3] above, wherein the (C) initiator is a peroxide type.

[0018] 〔5〕 Further, it is a resin composition according to any one of the above 〔1〕 to 〔4〕, which contains (E) a crosslinking agent, and the crosslinking agent is at least one selected from the group consisting of an ester acrylate compound, an epoxy acrylate compound, a urethane acrylate compound, an ether acrylate compound, a melamine acrylate compound, an alkyd acrylate compound, a silicon acrylate compound, triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, vinyl toluene, ethyl vinyl benzene, styrene, polypara methylstyrene, and a polyfunctional epoxy compound.

[0019] 〔6〕 Further, it is a resin composition according to any one of the above 〔1〕 to 〔5〕, which contains (F) a polyphenylene ether resin.

[0020] 〔7〕 Further, it is a resin composition according to any one of the above 〔1〕 to 〔6〕, which contains (D-2) alumina and / or aluminum nitride as a second inorganic filler.

[0021] 〔8〕 Further, it is a resin composition according to any one of the above 〔1〕 to 〔7〕, which contains (G) a silane coupling agent.

[0022] 〔9〕 A varnish containing the resin composition according to any one of the above 〔1〕 to 〔8〕.

[0023] 〔10〕 An inorganic composite sheet formed by applying the varnish according to the above 〔9〕 to a carrier material and forming a varnish layer with a thickness of 100 to 200 μm in an uncured state.

[0024] 〔11〕 An inorganic composite sheet having an uncured varnish layer formed by applying the varnish according to the above (9) to a carrier material, wherein the inorganic composite sheet is formed by laminating two sheets to a thickness of 100 to 200 μm.

[0025] 〔12〕 A metal base substrate formed by laminating and molding the inorganic composite sheet according to the above 〔10〕 or 〔11〕. [Effects of the Invention]

[0026] The resin composition of the present invention, comprising a polyfunctional unsaturated imide resin, synthetic rubber, and a specific inorganic filler, exhibits excellent flexibility and heat resistance, contributing to improved sheet handling. [Modes for carrying out the invention]

[0027] The following describes in detail one embodiment of the present invention. The present invention is not limited to the following embodiments. This invention is not intended to be implemented in a manner that impairs the effects of the present invention, but rather to be carried out with appropriate modifications within a range that does not hinder the effects of the present invention. can.

[0028] <Resin composition> The resin composition of this embodiment comprises (A) a polyfunctional unsaturated imide resin, (B) synthetic rubber, (C) and (D-1) a first inorganic filler, wherein (D-1) the first inorganic filler is boron nitride with an average particle size of 10 to 80 μm.

[0029] [(A) Polyfunctional unsaturated imide resin] The polyfunctional unsaturated imide resin used in the present invention is represented by the following general formula (1).

[0030] [ka]

[0031] In the formula, Z represents a divalent group containing a carbon-carbon double bond, and R 1 represents an organic group with two or more functions, and k is an integer greater than or equal to 2.

[0032] Z is not particularly limited, but may be a carbon-carbon double bond, a benzene ring, or a naphthalene ring.

[0033] R 1 While not particularly limited, examples of structural formulas include the following:

[0034] [ka]

[0035] In the formula, n is an integer from 1 to 6, Y is either a direct bond with nitrogen or a methylene group, X is either a direct bond, a methylene group, an ester group, a sulfonyl group, or a cyclohexyl group, and R 2 This represents one of the following: a hydrogen atom, a methyl group, an ethyl group, or a methylene group.

[0036] R 1 From the viewpoint of the flexibility of the resulting inorganic composite sheet, the above general formulas (2), (5), and (6) are good; from the viewpoint of the heat dissipation of the resulting inorganic composite sheet, the above general formulas (3) and (4) are good; and from the viewpoint of heat resistance, the above general formulas (3) and (4) are good.

[0037] The polyfunctional unsaturated imide resin is not particularly limited, and examples include 4,4'-diphenylmethanebismaleimide, polyphenylmethanebismaleimide, m-phenylenebismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, N,N'-ethylene-bis-imide maleate, N,N'-hexamethylene-bis-imide maleate, N,N'-metaphenylene-bis-imide maleate, N,N'-paraphenylene-bis-imide maleate, N,N'-4,4'-diphenylmethane-bis-imide maleate, N,N'-4,4'-diphenyl ether-bis-imide maleate, N,N'-4, Examples include 4'-diphenylsulfone-bis-imide, N,N'-4,4'-dicyclohexylmethane-bis-imide maleate, N,N'-α,α'-4,4'-dimethylenecyclohexane-bis-imide maleate, N,N'-metaxylylene-bis-imide maleate, and N,N'-diphenylcyclohexane-bis-imide maleate, but structures containing a phenylmaleimide group are particularly preferred from the viewpoint of heat resistance.

[0038] The amount of polyfunctional unsaturated imide resin is preferably 5 to 90 parts by mass, more preferably 10 to 70 parts by mass, and particularly preferably 45 to 75 parts by mass, when the total amount of the resin composition (excluding inorganic fillers) is 100 parts by mass. If the amount of polyfunctional unsaturated imide resin is above the lower limit, the sheet will have excellent heat resistance, and if it is below the upper limit, the sheet will have excellent flexibility, which is preferable.

[0039] Polyfunctional unsaturated imide resins can also be used as a substitute for the crosslinking agents described later. In this case, at least two types of polyfunctional unsaturated imide resins are used in combination.

[0040] [(B) Synthetic rubber] The synthetic rubber is not particularly limited, but it is preferably at least one selected from the group consisting of, for example, 1,2-polybutadiene, 1,4-polybutadiene, styrene-butadiene, malee-modified 1,2-polybutadiene, acrylic-modified 1,2-polybutadiene, styrene-ethylenepropylene, epoxy-modified 1,2-polybutadiene, and rubbers. From the viewpoint of electrical properties and heat resistance, styrene-butadiene and epoxy-modified 1,2-polybutadiene are particularly preferred. The inclusion of synthetic rubber is preferable because it improves the flexibility and adhesion to metals of the resulting resin composition.

[0041] The amount of synthetic rubber added is preferably 1 to 40 parts by mass, more preferably 2 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, when the total resin composition (excluding inorganic fillers) is 100 parts by mass. When the amount of synthetic rubber added is above the lower limit, the sheet handling properties are excellent, and when it is below the upper limit, the moldability properties are excellent, which is preferable.

[0042] [(C) Initiator] The initiator is not particularly limited, but more preferably has a decomposition temperature of 100 to 150°C. Examples of initiators include sulfur-based, peroxide-based, quinoid-based, and bismaleimide-based initiators. In this specification, "decomposition temperature" refers to the 10-hour half-life temperature.

[0043] Examples of sulfur-based compounds include sulfur, tetramethylthiraum disulfide, 2-(morpholinodithio)benzothiazole, and morpholin disulfide.

[0044] Examples of the aforementioned peroxide systems include dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl peroxide, 2·5-dimethyl-2·5-di-tert-butylperoxyhexin-3, 2·5-dimethyl-2·5-di-tert-butylperoxyhexane, and α·α'-bis(tert-butylperoxy-m-isopropyl)benzene.

[0045] Examples of the aforementioned quinoids include p-quinone dioximes, p,p'-dibenzoylquinone dioxides, and p-nitrosobenzenes.

[0046] Examples of the bismaleimide system include 4,4'-bismaleimidediphenylamine and N,N'-m-phenylenebismaleimide.

[0047] The initiator is preferably a peroxide-based agent, and more preferably a dicumyl peroxide. A peroxide-based agent is preferable because the reaction does not proceed at the temperature at which the solvent is removed when preparing a sheet from the varnish.

[0048] The amount of initiator added is preferably 0.5 to 5 parts by mass when the total resin composition (excluding inorganic fillers) is 100 parts by mass. Being within this range allows the crosslinking reaction to proceed efficiently.

[0049] [Inorganic fillers] ≪(D-1) First Inorganic Filler≫ (Boron nitride) Boron nitride is aggregated boron nitride or bulk boron nitride, in which flaky boron nitride is randomly oriented. Using aggregated boron nitride or bulk boron nitride is preferable because it suppresses the orientation of boron nitride in the planar direction, thereby improving the thermal conductivity in the thickness direction when used in the inorganic composite sheet described later.

[0050] The average particle size of the boron nitride is preferably 10 μm or more and 80 μm or less, and more preferably 30 μm or more and 70 μm or less. Being within this range is preferable because it improves the thermal conductivity of the resulting cured product. In this invention, the "average particle size" of the first inorganic filler refers to the particle size of aggregated or clumpy secondary particles.

[0051] The boron nitride used in this embodiment can be a commercially available product, such as HP-40MF, HP40-J2 (manufactured by JFE Corporation), PTX60 (manufactured by Momentive Corporation), and Agglomerates 50 (manufactured by 3M Corporation). Preferably, it is HP-40MF or HP40-J2 (manufactured by JFE Corporation) that has been calcined and produced as aggregates without internal voids.

[0052] The boron nitride of this embodiment can also be produced by known methods. For example, the method described in Japanese Patent Application Publication No. 2019-073409 can be used.

[0053] In the resin composition of this embodiment, the boron nitride content may be 60 to 85 wt%, preferably 65 to 80 wt%, based on 100 units of the total solid content of the resin composition.

[0054] ≪(D-2) Second Inorganic Filler≫ The resin composition of the present invention may contain a second inorganic filler, and examples of the second inorganic filler include alumina and / or aluminum nitride. Alumina and / or aluminum nitride are preferred because they have excellent thermal conductivity.

[0055] (alumina) In this embodiment, "alumina" refers to aluminum oxide, and may be transition alumina in various crystalline forms such as γ, δ, θ, κ, or may contain alumina hydrate within the transition alumina. However, it is basically preferable that it be in the α crystalline form due to its superior stability.

[0056] The alumina is preferably spherical or polyhedral, and more preferably polyhedral with 14 or more faces. Having 14 or more faces is preferable because, compared to polyhedra with fewer than 14 faces, the inter-face distance between particles becomes smaller, making it easier to obtain excellent thermal conductivity.

[0057] The shape of alumina can be confirmed using a scanning electron microscope (SEM). Using a JEOL JCM7000, images obtained from multiple SEM images from arbitrary fields of view of the sample are observed. Then, based on the observation results of 50 randomly selected alumina particles, the shape of 60% or more particles can be determined to be the shape possessed by that sample.

[0058] In this embodiment, the average particle size of the alumina is preferably 25 μm or more and 45 μm or less. An average particle size of 25 μm or more is preferable because it suppresses an increase in viscosity when used as a varnish. An average particle size of 45 μm or less is preferable because it provides excellent sheet processability.

[0059] In this specification, "average particle size" refers to the value calculated as the volume-based median diameter D50 from the volume-based cumulative particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer. .

[0060] In the resin composition of this embodiment, the alumina content may be 30 to 80 parts by mass, or 40 to 70 parts by mass, per 100 parts by mass of the total solid content of the resin composition. The preferred alumina content can be set according to the boron nitride content described later.

[0061] The alumina used in this embodiment may be commercially available alumina particles, or alumina particles produced by the method described in Japanese Patent Application Publication No. 2016-028993 and International Publication No. 2021 / 070729 may be used.

[0062] Commercially available alumina particles include DAW45 (Denka Co., Ltd.), CB-A20S, CB-AS30S, CB-P15 (Resonac Co., Ltd.), AZ series (Nippon Steel Material & Chemical Co., Ltd.), AH40-S (DIC Corporation), and AO-502 (Admatex Co., Ltd.). From the perspective of fluidity, CB-A20S, CB-A30S, CB-P15 (Resonac Co., Ltd.), and AO-502 (Admatex Co., Ltd.) are preferable, while AH40-S (DIC Corporation) is preferable for thermal conductivity, but the material is not limited to these.

[0063] These alumina particles may be used individually or in combination, but it is preferable to use them in combination. When using them in combination, it is preferable that polyhedral alumina particles make up 50% by mass or more of the total alumina, and more preferably 60% by mass or more. Being within this range is preferable because it results in particularly excellent thermal conductivity for the resulting inorganic composite sheet and metal base substrate.

[0064] (aluminum nitride) As the aluminum nitride, known and commonly used materials can be used, but it is preferable that the aluminum nitride is granular with an average particle size of 0.5 to 100 μm. Examples of commercially available aluminum nitride include, but are not limited to, FAN-f05-A1, FAN-f30-A1, FAN-f50-A1, and FAN-f80-A1 (manufactured by Furukawa Electronics Co., Ltd.).

[0065] In the resin composition of this embodiment, a first inorganic filler and a second inorganic filler can be used in combination. When used in combination, the total content of the first and second inorganic fillers is preferably 60 to 85 parts by mass, and more preferably 65 to 80 parts by mass, per 100 parts by mass of the total solid content of the resin composition. Being within this range suppresses the increase in viscosity of the resin composition or its varnish, and allows for the formation of a uniform coating film.

[0066] Within the aforementioned range, the content of the first inorganic filler and the second inorganic filler may be in any combination, but the mass ratio of the first inorganic filler to the second inorganic filler is preferably 50:50 to 5:95, more preferably 45:55 to 10:90, and particularly preferably 40:60 to 15:85. Within this range is preferable because it allows for excellent levels of both thermal conductivity and insulation reliability.

[0067] By combining the first inorganic filler and the second inorganic filler, a superior thermal conductivity can be obtained compared to conventional methods, thus reducing the amount of filler in the resin composition. Furthermore, the reduced amount of filler leads to a higher dielectric breakdown voltage of the resin composition, and the variation in dielectric breakdown voltage is suppressed, thereby stabilizing the electrical properties. From the viewpoint of the resulting properties, the first inorganic filler alone is particularly preferable.

[0068] [(E) Crosslinking agent] The resin composition of the present invention may further contain a crosslinking agent. The crosslinking agent is not particularly limited, but for example, it is at least one selected from the group consisting of ester acrylate compounds, epoxy acrylate compounds, urethane acrylate compounds, ether acrylate compounds, melamine acrylate compounds, alkyd acrylate compounds, silicon acrylate compounds, triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, vinyltoluene, ethyl vinylbenzene, styrene, poly-p-methylstyrene, and polyfunctional epoxy compounds, and triallyl isocyanurate is particularly preferred from the viewpoint of electrical properties and heat resistance. Furthermore, the aforementioned crosslinking agent does not include the polyfunctional unsaturated imide mentioned above.

[0069] The amount of crosslinking agent is preferably 10 to 50 parts by mass, and more preferably 20 to 40 parts by mass, when the total resin composition (excluding inorganic fillers) is 100 parts by mass. It is preferable to have an amount below the upper limit because it improves sheet handling performance.

[0070] [(F) Polyphenylene ether resin] The resin composition of the present invention may further contain a polyphenylene ether resin. The polyphenylene ether resin can be obtained, for example, by polycondensation of a compound having a phenolic hydroxyl group alone, or by copolymerization of two or more such compounds. Using a polyphenylene ether resin can suppress the increase in fluidity of the resin composition and improve its heat resistance.

[0071] Examples of compounds having the aforementioned phenolic hydroxyl group include 2,6-dimethylphenol, 2,6-diethylphenol, 2,6-dipropylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-propylphenol, 2-ethyl-6-propylphenol, m-cresol, 2,3-dimethylphenol, 2,3-dipropylphenol, 2-methyl-3-ethylphenol, 2-methyl-3-propylphenol, 2-ethyl-3-methylphenol, 2-ethyl-3-propylphenol, 2-propyl-3-methylphenol, 2-propyl-3-ethylphenol, 2,3,6-trimethylphenol, 2,3,6-triethylphenol, 2,3,6-tripropylphenol, 2,6-dimethyl-3-ethylphenol, and 2,6-dimethyl-3-propylphenol.

[0072] Specific examples of polyphenylene ether resins obtained by the sole polycondensation or copolymerization of the compounds having phenolic hydroxyl groups include poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether, and 2,6-dimethylphenylene Examples include 2,6-moleol / 2,3,6-trimethylphenol copolymer, 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer, 2,6-diethylphenol / 2,3,6-trimethylphenol copolymer, 2,6-dipropylphenol / 2,3,6-trimethylphenol copolymer, graft copolymer obtained by graft polymerization of styrene onto poly(2,6-dimethyl-1,4-phenylene) ether, and graft copolymer obtained by graft polymerization of styrene onto 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer.

[0073] Furthermore, polyphenylene ether resins are sometimes commercially available in the form of alloyed polymers with polystyrene and other materials. Such alloyed polymers can also be used. Examples of alloyed polymers include alloyed polymers of poly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, and alloyed polymers of poly(2,6-dimethyl-1,4-phenylene) ether and styrene-butadiene copolymer.

[0074] Among polyphenylene ether resins, those having 1 to 4 methyl groups bonded to the carbon atoms of each phenylene skeleton are preferred. Furthermore, the polyphenylene ether resin preferably has a weight-average molecular weight of 500 to 5000, more preferably 500 to 2000, and even more preferably 1000 to 2000. The weight-average molecular weight is measured using gel permeation chromatography (GPC) and converted to polystyrene equivalent.

[0075] While there are no particular restrictions on the amount of polyphenylene ether resin blended, it is preferable that the amount be 25 parts by mass or less, and preferably 13 to 15 parts by mass, when the total solid content of the resin composition is 100 parts by mass, in order to obtain good cured product properties. Within this range, the peel strength of the resulting inorganic composite sheet is excellent and therefore preferable.

[0076] The polyphenylene ether resin is more preferably a terminally modified polyphenylene ether resin, which is terminally modified by substituents having unsaturated double bonds with 2 to 15 carbon atoms in the molecule.

[0077] Substituents having an unsaturated double bond with 2 to 15 carbon atoms in the molecule are not particularly limited in structure, but examples include the following formula.

[0078] [ka]

[0079] In formula (7), Y represents a hydrocarbon group having 1 to 13 carbon atoms, an arylene group, or a carbonyl group. R2 independently represents a hydrogen atom, a hydroxyl group, or a hydrocarbon group having 1 to 13 carbon atoms (e.g., a linear hydrocarbon group, a cyclic hydrocarbon group), an aryl group, an alkoxy group, an aryloxy group, an amino group, or a hydroxyl group.

[0080] The terminally modified polyphenylene ether preferably has an average number of substituents (number of terminal substituents) per molecule that have an unsaturated double bond with 2 to 15 carbon atoms at the molecular ends of 1.5 to 3, more preferably 1.7 to 2.7, and even more preferably 1.8 to 2.5. Being within this range is preferable because it allows for sufficient crosslinking to be formed, resulting in excellent heat resistance of the resulting cured product, suppression of excessive reaction progression, and excellent storage stability and fluidity maintenance of the resin composition.

[0081] The number of terminal substituents in a terminally modified polyphenylene ether can be expressed as the average value of the number of substituents per molecule of all terminally modified polyphenylene ether present in one mole of the terminally modified polyphenylene ether. This number of terminal substituents can be measured, for example, by measuring the number of hydroxyl groups remaining in the obtained terminally modified polyphenylene ether and calculating the decrease from the number of hydroxyl groups in the polyphenylene ether before terminal modification. The number of hydroxyl groups remaining in a terminally modified polyphenylene ether can be measured by adding a quaternary ammonium salt (tetraethylammonium hydroxide) that associates with hydroxyl groups to a solution of the terminally modified polyphenylene ether and measuring the UV absorbance of the resulting mixture.

[0082] [(G) Silane coupling agent] The resin composition of the present invention may further contain a silane coupling agent. Examples of silane coupling agents include epoxysilanes.

[0083] <Varnish> The resin composition of the present invention can be suitably used as a varnish. Known methods can be used to prepare the varnish; the resin composition can be dissolved (diluted) in an organic solvent to produce the varnish.

[0084] As the solvent, for example, polar solvents such as methyl ethyl ketone, methoxypropanol, N,N-dimethylformamide, and dimethyl sulfoxide can be used, and one solvent may be used alone or two or more solvents may be used in combination.

[0085] The amount of solvent used is not particularly limited and can be appropriately determined, for example, taking into account sheet processability. Specifically, it is preferable to prepare the resulting varnish so that its viscosity is between 3000 mPa·s and 15000 mPa·s. A viscosity of 3000 mPa·s or higher is preferable because it suppresses appearance defects due to repulsion during coating. A viscosity of 15000 mPa·s or lower is preferable because it suppresses appearance defects due to streaking during coating.

[0086] [Other ingredients] The aforementioned varnish may contain other components, to the extent that it does not impair the purpose of the present invention. Examples include dispersants.

[0087] The aforementioned dispersant is not particularly limited as long as it is a dispersant used for paints, but examples include Disperbyk-110, 111, 180, 161, BYK-W996, W9010, and W903. By using a dispersant, it is possible not only to improve the dispersibility of the inorganic filler but also to adjust the viscosity of the varnish within the above range.

[0088] <Inorganic composite sheet> The aforementioned varnish is suitably used for inorganic composite sheets. The inorganic composite sheet is obtained by applying the above-mentioned varnish to a carrier material and then heating and drying it. Furthermore, the inorganic composite sheet is formed in a semi-cured state on the surface of the carrier material. In other words, the heat drying process is a B-stage process, in which the varnish applied to the carrier material is heated to partially initiate the crosslinking reaction within the varnish. Therefore, the inorganic composite sheet of this embodiment has the property of melting once due to the heat and pressure of lamination molding and then curing.

[0089] The method of applying the varnish is not particularly limited and can be carried out by known methods. For example Methods such as comma coating, die coating, lip coating, and gravure coating are mentioned. One method for forming an inorganic composite sheet of a fixed thickness involves passing the material to be coated through the gaps. The comma coating method and the die coating method, in which varnish is applied from a nozzle with controlled flow rate, are preferred. .

[0090] The thickness of the inorganic composite sheet formed on the carrier material is 100 to 200 μm. This is preferable. A thickness of 200 μm or less is preferable because it reduces thermal resistance. The closer the thickness is to 0 μm, the more the generation of microvoids during sheet formation can be suppressed, and the higher the dielectric breakdown voltage, which is preferable. When using two inorganic composite sheets laminated together, it is preferable to adjust the thickness of each sheet so that the thickness after lamination pressing is 100 to 200 μm. The resin composition of the present invention allows for thinning compared to conventional ones, and the carrier material can be easily peeled off, making it possible to obtain an inorganic composite sheet with a thickness of 100 to 200 μm even when laminating and pressing two sheets together.

[0091] It is preferable to use a polymer film or a metal sheet as the carrier material. Examples of polymer films include polyethylene, polypropylene, polyvinyl chloride, and other polyolefins. Fins, polyethylene terephthalate and other polyesters, polycarbonates, acetyl cellulose Examples include lurose and tetrafluoroethylene. The metal sheet is a metal sheet Examples of metal foils include copper foil, aluminum foil, and nickel foil. Furthermore, release paper and the like can be used as carrier materials.

[0092] <Metal-based substrate> The inorganic composite sheet of the present invention can be laminated and suitably used as a metal base substrate. Specifically, two or more of the inorganic composite sheets obtained above are laminated to achieve the desired thickness. Later, metal foil is placed on the outermost layer of one or both sides to form a laminate, and this laminate is then pressed It is obtained by laminating and integrating materials through heating and pressurizing, similar to molding. Here, copper is used as the metal foil. Aluminum, brass, nickel, and other metal foils can be used individually, as well as alloys and composites. The heating and pressurizing conditions for the laminate are adjusted as needed to control the curing of the varnish. Pressurization is necessary, but if the pressurization pressure is too low, air bubbles will form inside the resulting metal base substrate. Because residue may remain and electrical properties may deteriorate, pressurize under conditions that satisfy moldability. This is preferable. For example, under conditions of a heating temperature of 100-200°C and a pressure of 0.98-4.9 MPa. By heating and pressurizing for 10 minutes to 2 hours, a metal base substrate can be obtained by integral molding. can. [Examples]

[0093] The present invention will be described in further detail below based on examples, but this description is not intended to limit the present invention.

[0094] [Preparation of resin] Resin compositions were prepared according to Table 1.

[0095] The materials used are as follows: (A) Polyfunctional unsaturated imide resin BMI-1: Phenylenemethanemaleimide (BMI-2300, equivalent amount of maleimide functional groups 180g / eq, manufactured by Yamato Chemical Industries, Ltd.) BMI-2: BMI-SE55 (Functional group equivalent 253, manufactured by KI Chemicals Co., Ltd.) BMI-3: BMI-689 (Functional group equivalent weight 350g / eq, Designer Molecule Inc.) BMI-4: BMI-3000 (Functional group equivalent weight 1500g / eq, Designer Molecule Inc.) (B) Synthetic rubber Synthetic rubber-1: Hydrogenated styrene-ethylene propylene block copolymer (S2002, manufactured by Kuraray Co., Ltd.) Synthetic rubber-2: Styrene-butadiene copolymer (liquid 1,2-SBS, manufactured by Nippon Soda Co., Ltd.) Synthetic rubber-3:1,2-polybutadiene homopolymer (B-3000, manufactured by Nippon Soda Co., Ltd.) (C) Initiator Initiator-1: α·α'-bis(tert-butylperox-m-isopropyl)benzene (Perbutyl P, manufactured by NOF Corporation) (D) Inorganic fillers a: HP40MF100 (D50=36um, manufactured by JFE Corporation) b: HP40J2WP (D50=16um, manufactured by JFE Corporation) c:FAN-f05 (D50=5um, manufactured by Furukawa Denshi) (E) Crosslinking agent Crosslinking agent-1: Triallyl isocyanurate (TAIC, manufactured by Shinryo Co., Ltd.) Crosslinking agent-2: Tricyclodecanedimethanol dimethacrylate (DCP, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) Crosslinking agent-3: Trimethylolpropane trimethacrelite (TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) (F) Polyphenylene ether resin PPE-1: Reactive low molecular weight polyphenylene ether (Noryl SA9000 resin, manufactured by SHPP Japan LLC) PPE-2: Vinyl benzyl ether-terminated oligonucleotide (2,6-dimethyl-1,4-phenylene ether) (OPE-2St1200, manufactured by Mitsubishi Gas Chemical Company)

[0096] [Table 1]

[0097] [Examples 1-10, Comparative Example 1] The obtained resin composition was used to fabricate inorganic composite sheets and metal-based substrates according to the following method, and these were then evaluated.

[0098] (Fabrication of metal-based substrates) The obtained resin composition was kneaded in a planetary mixer, and a predetermined amount of solvent (toluene) was added to adjust the viscosity to 3000 mPa·s to obtain a varnish. Next, this varnish was applied to a polyethylene terephthalate (PET) film with a thickness of 75 μm, and heated and dried at 130°C for 8 minutes to form an inorganic composite sheet in the B-stage state with a thickness of 150 μm on one side of the carrier material.

[0099] One inorganic composite sheet was stacked, and an 18 μm copper foil was placed on the coated sheet and 1 mm aluminum plate. The sheet was then heated and compressed in a vacuum at a temperature of 175°C and a pressure of 2.94 MPa for 30 minutes to produce a metal base substrate. In the comparative example using epoxy, since the above conditions were not feasible, the heating temperature was changed to 175°C and the pressure to 2.94 MPa for 90 minutes, and the sheet was then heated and compressed.

[0100] [Evaluation Method] (Average particle size D50) This value is calculated as the volume-based median diameter D50 from the volume-based cumulative particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer.

[0101] (Thermal conductivity) Inorganic composite sheets were laminated and heated and pressure-molded in a vacuum at a temperature of 175°C and a pressure of 2.94 MPa for 90 minutes to obtain a 1 mm thick sheet. The thermal diffusivity and specific heat of the sheet were measured at 25°C using a thermal conductivity measuring device (LFA467 HyperFlash, manufactured by NETZSCH). Next, the density of this heat dissipation material was measured by the Archimedes method. The thermal conductivity of this heat dissipation material was estimated from the product of the obtained thermal diffusivity, specific heat, and density.

[0102] (Seat handling) Varnish was applied to a PET film using a film applicator and dried at 100°C for 15 minutes. After drying, the edges of the sheet were observed to check for warping. Handling was evaluated by checking for cracking, chipping, and powder fallout during the cutting process.

[0103] (DMA-Tg) Inorganic composite sheets were laminated and heated and pressure-molded in a vacuum at a heating temperature of 175°C and a pressure of 2.94 MPa for 90 minutes to obtain a 1 mm thick sheet cured product. The glass transition temperature (Tg) (°C) of the sheet cured product was measured using a Hitachi High-Tech DMA device (DMA7100) under heating conditions of 20°C / min from room temperature, and the TanΔ peak temperature observed was measured. A glass transition temperature (Tg) of 200°C or higher is acceptable for practical purposes, and more preferably 250°C or higher. Furthermore, the Tg of the cured products obtained in the examples was 200°C or higher in all cases.

[0104] [Table 2]

[0105] [Table 3]

Claims

1. (A) a polyfunctional unsaturated imide resin, (B) synthetic rubber, (C) an initiator, and (D-1) a first inorganic filler, A resin composition characterized in that the (D-1) first inorganic filler is boron nitride with an average particle size of 10 to 80 μm.

2. The resin composition according to claim 1, wherein the (A) polyfunctional unsaturated imide resin is represented by the following general formula (1). 【Chemistry 1】 (In the formula, Z represents a divalent group containing a carbon-carbon double bond, R １ (where represents a two- or more functional organic group, and k is an integer greater than or equal to 2.)

3. The resin composition according to claim 1 or 2, wherein the synthetic rubber (B) is at least one selected from the group consisting of 1,2-polybutadiene, 1,4-polybutadiene, styrene-butadiene, malee-modified 1,2-polybutadiene, acrylic-modified 1,2-polybutadiene, styrene-ethylenepropylene, epoxy-modified 1,2-polybutadiene, and rubbers.

4. The resin composition according to claim 1 or 2, wherein the (C) initiator is a peroxide type.

5. Furthermore, the resin composition according to claim 1 or 2, comprising (E) a crosslinking agent, wherein the crosslinking agent is at least one selected from the group consisting of ester acrylate compounds, epoxy acrylate compounds, urethane acrylate compounds, ether acrylate compounds, melamine acrylate compounds, alkyd acrylate compounds, silicon acrylate compounds, triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, vinyltoluene, ethyl vinylbenzene, styrene, poly-p-methylstyrene, and polyfunctional epoxy compounds.

6. Furthermore, the resin composition according to claim 1 or 2, further comprising (F) a polyphenylene ether resin.

7. Furthermore, (D-2) the resin composition according to claim 1 or 2, comprising alumina and / or aluminum nitride as a second inorganic filler.

8. Furthermore, the resin composition according to claim 1 or 2, comprising (G) a silane coupling agent.

9. A varnish containing the resin composition according to claim 1 or 2.

10. An inorganic composite sheet comprising applying the varnish described in claim 9 to a carrier material, and forming the varnish layer to a thickness of 100 to 200 μm while it is still uncured.

11. An inorganic composite sheet having an uncured varnish layer formed by applying the varnish described in claim 9 to a carrier material, wherein two inorganic composite sheets are laminated to form a thickness of 100 to 200 μm.

12. A metal base substrate obtained by laminating an inorganic composite sheet according to claim 9 or 10.

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