Resin compositions, sheets, metal-based substrates

Abstract

The objective is to provide a resin composition, varnish, inorganic composite sheet thereof, and metal-based substrate that improves thermal conductivity and insulation reliability while contributing to peelability and flexibility. [Solution] A resin composition is provided comprising (A) a polyphenylene ether resin, (B) a synthetic rubber, (C) a crosslinking agent, (D) an initiator, and (E-1) a first inorganic filler, wherein (B) the synthetic rubber is a copolymer having aromatic groups, and (E-1) the 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-based substrate.

Background Art

[0002] In recent years, with the demands for miniaturization, high-frequency operation, 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 has been progressing.

[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 aggregates 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 aggregates 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 novolacifying a divalent phenol compound, and a mixed filler of α-alumina and boron nitride.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described in Patent Documents 1 and 2, epoxy resin compositions are generally used for printed circuit boards. This is because epoxy resin compositions are excellent at being molded into sheets and B-staged, and also have excellent mechanical properties and heat resistance when cured.

[0007] However, inorganic composite sheets using the resin compositions described in Patent Documents 1 and 2 did not have sufficient release properties and also lacked flexibility.

[0008] 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 improve thermal conductivity and insulation reliability while contributing to peelability and flexibility. [Means for solving the problem]

[0009] The inventors diligently conducted research to solve the above problems. As a result, they found that a resin composition containing a polyphenylene ether resin, a crosslinkable resin, and a specific inorganic filler exhibits excellent peelability, flexibility, and handling properties when formed into an inorganic composite sheet.

[0010] In other words, the present invention includes the following embodiments. (1) A resin composition comprising (A) a polyphenylene ether resin, (B) a synthetic rubber, (C) a crosslinking agent, (D) an initiator, and (E-1) a first inorganic filler, wherein (B) the synthetic rubber is a copolymer having aromatic groups, and (E-1) the first inorganic filler is boron nitride with an average particle size of 10 to 80 μm. (2) The resin composition according to (1), wherein the (A) polyphenylene ether resin is a terminally modified polyphenylene ether resin having substituents having an unsaturated double bond with 2 to 15 carbon atoms in the molecule. (3) The resin composition according to (1) or (2) above, wherein the synthetic rubber (B) has a weight-average molecular weight of 3,000 to 75,000. (4) The resin composition according to any one of (1) to (3) above, wherein the styrene content in the synthetic rubber of (B) is 1 to 50%. (5) The resin composition according to any one of (1) to (4) above, further comprising (E-2) alumina and / or aluminum nitride as a second inorganic filler. (6) The resin composition according to any one of (1) to (5) above, further comprising (F) a silane coupling agent. (7) A varnish containing the resin composition described in any one of (1) to (6) above. (8) An inorganic composite sheet obtained by applying the varnish described in (7) above to a carrier material and forming the varnish layer to a thickness of 100 to 200 μm while the varnish layer is still uncured. (9) An inorganic composite sheet having an uncured varnish layer formed by applying the varnish described in (7) above to a carrier material, wherein two inorganic composite sheets are laminated to form a thickness of 100 to 200 μm. (10) A metal base substrate obtained by laminating the inorganic composite sheets described in (8) or (9) above. [Effects of the Invention]

[0011] The resin composition of the present invention, by using a polyphenylene ether resin, a specific synthetic rubber, and a specific inorganic filler, exhibits excellent thermal conductivity and insulation reliability, and contributes to improved sheet handling performance. [Modes for carrying out the invention]

[0012] 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.

[0013] <Resin composition> The resin composition of this embodiment comprises (A) a polyphenylene ether resin, (B) a synthetic rubber, (C) a crosslinking agent, (D) an initiator, and (E-1) a first inorganic filler, wherein (B) the synthetic rubber is a copolymer having aromatic groups, and (E-1) the first inorganic filler is boron nitride with an average particle size of 10 to 80 μm.

[0014] [(A) Polyphenylene ether resin] The polyphenylene ether resin used in the present invention 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 high fluidity of the resin composition, and the resulting cured product exhibits low dielectric properties, thereby improving insulation reliability.

[0015] 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.

[0016] Specific examples of the polyphenylene ether resin obtained by the homopolycondensation or copolymerization of the compound having a phenolic hydroxyl group 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, 2,6-dimethylphenol / 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, a graft copolymer obtained by graft-polymerizing styrene onto poly(2,6-dimethyl-1,4-phenylene) ether, and a graft copolymer obtained by graft-polymerizing styrene onto 2,6-dimethylphenol / 2,3,6-trimethylphenol copolymer.

[0017] In addition, the polyphenylene ether resin used in the present invention may be commercially available in the form of an alloy polymer with polystyrene or the like. Such an alloy polymer can also be used. Examples of the alloy polymer include an alloy polymer of poly(2,6-dimethyl-1,4-phenylene) ether and polystyrene, and an alloy polymer of poly(2,6-dimethyl-1,4-phenylene) ether and styrene-butadiene copolymer.

[0018] Among the polyphenylene ether resins used in the present invention, a resin having 1 to 4 methyl groups bonded to the carbon atoms of the phenylene skeleton per phenylene skeleton is preferred. Further, the polyphenylene ether resin preferably has a weight average molecular weight of 500 or more and 5000 or less, more preferably 500 or more and 2000 or less, and even more preferably 1000 or more and 2000 or less. The weight average molecular weight is measured using gel permeation chromatography (GPC) and is a value in terms of polystyrene.

[0019] Although there is no particular limitation on the blending amount of the polyphenylene ether resin in the resin composition of the present invention, from the viewpoint of obtaining good cured product properties, when the total solid content of the resin composition is 100 parts by mass, it is preferably 25 parts by mass or less, and preferably 13 to 15 parts by mass. When it is within the above range, the peel strength of the obtained inorganic composite sheet is excellent, which is preferable.

[0020] The polyphenylene ether resin of the present invention is more preferably a terminally modified polyphenylene ether resin modified at the terminal with a substituent having an unsaturated double bond having 2 to 15 carbon atoms in the molecule.

[0021] The substituent having an unsaturated double bond having 2 to 15 carbon atoms in the molecule is not particularly limited in structure, and examples thereof include the following formula.

[0022]

Chemical formula

[0023] In formula (1), Y represents a hydrocarbon group having 1 to 13 carbon atoms, an arylene group, or a carbonyl group. Each R1 independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 13 carbon atoms (for example, a chain hydrocarbon group, a cyclic hydrocarbon group), an aryl group, an alkoxy group, an allyloxy group, an amino group, or a hydroxyl group.

[0024] In the terminally modified polyphenylene ether of the present embodiment, the average number of substituents having an unsaturated double bond having 2 to 15 carbon atoms in the molecule at the molecular terminal (terminal substitution number) per molecule of the terminally modified polyphenylene ether is preferably 1.5 to 3, more preferably 1.7 to 2.7, and even more preferably 1.8 to 2.5. When it is within the above range, crosslinking points are sufficiently formed, the heat resistance of the obtained cured product is excellent, and the excessive progress of the reaction is suppressed, so that the storage stability and fluidity maintenance of the resin composition are excellent, which is preferable.

[0025] 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.

[0026] [(B) Synthetic rubber] The synthetic rubber used in the present invention may be any rubber having aromatic groups, and is preferably at least one selected from the group consisting of styrene-butadiene, styrene-butadiene-styrene, malee-modified 1,2-polybutadiene, acrylic-modified 1,2-polybutadiene, epoxy-modified 1,2-polybutadiene-styrene conjugated diene block copolymer, hydrogenated styrene-conjugated diene block copolymer, and styrene-ethylene-propylene-styrene. From the viewpoint of electrical properties, heat resistance, and compatibility with polyphenylene ether resin, copolymers and block copolymers of styrene-butadiene, styrene-butadiene-styrene, and styrene-ethylene-propylene-styrene are particularly preferred. Furthermore, the presence of unsaturated reactive groups is even more preferable as it further improves heat resistance. The presence of aromatic groups results in excellent compatibility with the polyphenylene ether resin, and as a result, when used as a varnish, phase separation does not occur, improving the peelability and flexibility of the sheet.

[0027] The weight-average molecular weight of the synthetic rubber may be between 2,000 and 100,000, or between 3,000 and 75,000. A molecular weight below the upper limit is preferable as it facilitates flow during molding, while a molecular weight above the lower limit is preferable from the viewpoint of sheet handling properties. Furthermore, a liquid state of the synthetic rubber is preferable in terms of fluidity during molding.

[0028] The styrene content in the synthetic rubber is preferably 1 to 50%. Within this range, it is preferable from the viewpoint of flexibility and compatibility with polyphenylene ether.

[0029] The amount of synthetic rubber blended in the resin composition of the present invention is not particularly limited, but from the standpoint of good cured product properties, it is preferably 40 parts by mass or less, and preferably 5 to 30 parts by mass, when the total solid content of the resin composition is 100 parts by mass. When the blending is within this range, the resulting inorganic composite sheet has excellent flexibility, which is preferable.

[0030] [(C) Crosslinking agent] The crosslinking agent is not particularly limited, but 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, bismaleimide compounds, triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, vinyltoluene, ethyl vinylbenzene, styrene, poly-p-methylstyrene, and polyfunctional epoxy compounds, and is preferably a rigid skeleton from the viewpoint of heat resistance, and is particularly preferably isocyanurate, benzene, dicyclopentadiene, etc.

[0031] The amount of crosslinking agent is preferably 10 to 70 parts by mass, more preferably 20 to 65 parts by mass, and particularly preferably 35 to 50 parts by mass, when the total resin composition (excluding inorganic fillers) is 100 parts by mass. A value below the upper limit is preferable because it improves insulation reliability and heat resistance. A value above the lower limit is preferable because it improves moldability.

[0032] [(D) 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, and quinoid-based initiators. In this specification, "decomposition temperature" refers to the 10-hour half-life temperature.

[0033] Examples of sulfur-based compounds include sulfur, tetramethylthiraum disulfide, 2-(morpholinodithio)benzothiazole, and morpholin disulfide.

[0034] 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.

[0035] Examples of the aforementioned quinoids include p-quinone dioximes, p,p'-dibenzoylquinone dioxides, and p-nitrosobenzenes.

[0036] Examples of the bismaleimide system include 4,4'-bismaleimidediphenylamine and N,N'-m-phenylenebismaleimide.

[0037] 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.

[0038] The amount of initiator added is preferably 0.5 to 5 wt% when the total resin composition (excluding inorganic fillers) is considered as 100. Being within this range allows the crosslinking reaction to proceed efficiently.

[0039] [Inorganic fillers] ≪(E-1) First Inorganic Filler≫ (Boron nitride) The boron nitride in this embodiment 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, and when used in the inorganic composite sheet described later, the thermal conductivity in the thickness direction is improved.

[0040] 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.

[0041] The boron nitride used in this embodiment can be a commercially available product, such as HP-40MF, HP40-J2 (manufactured by Mizushima Iron Alloy Co., Ltd.), PTX60 (manufactured by Momentive Corporation), and Agglomerates 50 (manufactured by 3M Corporation). Preferably, HP-40MF or HP40-J2 (manufactured by Mizushima Iron Alloy Co., Ltd.), which are produced as aggregates by firing and have no internal voids, are used.

[0042] 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.

[0043] In the resin composition of this embodiment, the boron nitride content may be 60 to 85 wt%, and preferably 65 to 80 wt%, when the total solid content of the resin composition is 100.

[0044] ≪(E-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.

[0045] (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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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. .

[0050] In the resin composition of this embodiment, the alumina content may be 30 to 80 wt%, or 40 to 70 wt%, when the total solid content of the resin composition is 100. The preferred alumina content can be set according to the boron nitride content described later.

[0051] 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.

[0052] 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.

[0053] 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 wt% or more of the total alumina, and more preferably 60 wt% 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.

[0054] (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.).

[0055] 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 wt%, and more preferably 65 to 80 wt%, when the total solid content of the resin composition is 100. 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.

[0056] 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 1:99, more preferably 45:55 to 3:97, and particularly preferably 40:60 to 5:95. Within this range is preferable because it allows for excellent levels of both thermal conductivity and insulation reliability.

[0057] 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.

[0058] [(F) Silane coupling agent] The resin composition of the present invention may further contain a silane coupling agent. Examples of silane coupling agents include vinylsilane and epoxysilane.

[0059] <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.

[0060] 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.

[0061] 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 1000 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.

[0062] [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.

[0063] 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.

[0064] <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.

[0065] 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. .

[0066] 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.

[0067] 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.

[0068] <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]

[0069] The present invention will be described in further detail below based on examples, but this description is not intended to limit the present invention.

[0070] The materials used are as follows: (A) 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) (B) Synthetic rubber Synthetic rubber-1: Hydrogenated styrene-ethylene propylene block copolymer (S2002, manufactured by Kuraray Co., Ltd., weight-average molecular weight 54000, styrene content 30%) Synthetic Rubber-2: Styrene-butadiene copolymer (liquid 1,2-SBS, manufactured by Nippon Soda Co., Ltd., number average average molecular weight 4500, styrene content 20%) Synthetic rubber-3:1,2-polybutadiene homopolymer (B-1000, manufactured by Nippon Soda Co., Ltd., number average molecular weight 1200, weight average molecular weight 1100, styrene content 0%) (C) 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.) Crosslinking agent-4: Bismaleimide (BMI-689, manufactured by Designer Molecules) (D) Initiator Initiator-1: α·α'-bis(tert-butylperox-m-isopropyl)benzene (Perbutyl P, manufactured by NOF Corporation) (E) Inorganic fillers a: HP40MF100 (D50=36μm, manufactured by JFE Corporation) b: HP40J2WP (D50=16μm, manufactured by JFE Corporation) c:FAN-f05 (D50=5μm, manufactured by Furukawa Electronics)

[0071] [Examples 1-9, Comparative Example 1] Resin compositions were prepared according to Table 1, and inorganic composite sheets and metal-based substrates were fabricated and evaluated according to the following methods.

[0072] [Table 1]

[0073] (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.

[0074] 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.

[0075] [Evaluation Method] (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.

[0076] (Insulation reliability BDV) Test samples were obtained by etching the copper foil on the metal base substrate obtained in the examples and comparative examples described later, thereby patterning the copper foil into a circle with a diameter of 2.5 cm. Using 20 of the obtained test samples, an AC voltage was applied between the test samples, and the value at which dielectric breakdown occurred was measured and averaged.

[0077] (flexibility) Inorganic composite sheets were pressed against the outer circumference of a cylindrical jig with a diameter of φ760 mm, and the number of sheets that developed cracks or fissures on their surface was evaluated. The evaluation was performed using n=10. A result of 5 or fewer sheets indicates no practical problems.

[0078] (Peelability) We marked the inorganic composite sheets, cut into 150mm squares, with ○ if they could be peeled off the PET film and × if they could not be peeled off.

[0079] [Table 2]

Claims

1. (A) polyphenylene ether resin, (B) synthetic rubber, (C) crosslinking agent, (D) initiator, and (E-1) first inorganic filler, The synthetic rubber (B) is a copolymer having aromatic groups, A resin composition characterized in that the (E-1) first inorganic filler is boron nitride having an average particle size of 10 to 80 μm.

2. The resin composition according to claim 1, wherein the (A) polyphenylene ether resin is a terminally modified polyphenylene ether resin containing substituents having an unsaturated double bond with 2 to 15 carbon atoms in the molecule.

3. The resin composition according to claim 1 or 2, wherein the synthetic rubber (B) has a weight-average molecular weight of 3,000 to 75,000.

4. The resin composition according to claim 1 or 2, wherein the styrene content in the synthetic rubber (B) is 1 to 50%.

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

6. Furthermore, the resin composition according to claim 1, comprising (F) a silane coupling agent.

7. A varnish containing the resin composition described in claim 1.

8. An inorganic composite sheet comprising applying the varnish described in claim 7 to a carrier material, and forming the varnish layer to a thickness of 100 to 200 μm while it is still uncured.

9. An inorganic composite sheet having an uncured varnish layer formed by applying the varnish described in claim 7 to a carrier material, wherein two inorganic composite sheets are laminated to form a thickness of 100 to 200 μm.

10. A metal base substrate obtained by laminating an inorganic composite sheet according to claim 8 or 9.

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