Resin compositions, insulating resin cured bodies, laminates, and circuit boards

Abstract

A resin composition containing a thermosetting resin, an inorganic filler, a copolymer, and an inorganic ion scavenger, wherein the copolymer has a (meth)acrylic monomer unit A having an anionic group, a (meth)acrylic monomer unit B having a cationic group, and a (meth) acrylic monomer unit C other than the (meth)acrylic monomer unit A and the (meth)acrylic monomer unit B, wherein the content of the inorganic ion scavenger is 0.1-50 parts by mass per 100 parts by mass of the total of the thermosetting resin and the copolymer, and the content of the copolymer is 0.01-10 parts by mass per 100 parts by mass of the inorganic filler.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a resin composition, an insulating resin cured body, a laminate, and a circuit board, which are preferably used for manufacturing an insulating layer of a circuit board (metal base circuit board).

Background Art

[0002] Various circuit boards have been put into practical use as circuit boards for forming hybrid integrated circuits by mounting electronic and electrical components such as semiconductor elements. Circuit boards are classified into resin circuit boards, ceramic circuit boards, metal base circuit boards, etc. based on the substrate material.

[0003] Resin circuit boards are inexpensive but have low thermal conductivity of the substrate, so they are limited to applications that use relatively low power. Ceramic circuit boards are suitable for applications that use relatively high power because of the characteristics of ceramics such as high electrical insulation and heat resistance, but have the disadvantage of being expensive. On the other hand, metal base circuit boards have intermediate properties between the two and are suitable for general-purpose applications that use relatively high power, such as applications for inverters for refrigerators, inverters for commercial air conditioners, power supplies for industrial robots, and power supplies for automobiles.

[0004] For example, Patent Document 1 discloses a method for obtaining a circuit board excellent in stress relaxation property, heat resistance, moisture resistance, and heat dissipation by using a composition for a circuit board containing specific epoxy resin, curing agent, and inorganic filler as essential components.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Replacing ceramic circuit boards with metal-based circuit boards is expected to improve productivity. Furthermore, ceramic circuit boards have the drawback of being prone to solder cracking during thermal cycling; however, replacing them with metal-based circuit boards is expected to suppress the occurrence of solder cracks. On the other hand, since ceramic circuits are suitable for applications using relatively high power, replacing ceramic circuit boards with metal-based circuit boards requires improved insulation reliability against high DC voltage application (especially under high-temperature conditions).

[0007] Therefore, the present invention aims to provide a resin composition capable of forming an insulating layer with excellent insulating reliability against the application of high DC voltage under high temperature (150°C) conditions. Furthermore, the present invention aims to provide an insulating resin cured body which is a cured product of the resin composition, a laminate using the insulating resin cured body, and a circuit board. [Means for solving the problem]

[0008] The present invention includes the following embodiments. (1) A resin composition comprising a thermosetting resin, an inorganic filler, a copolymer, and an inorganic ion scavenger, wherein the copolymer comprises (meth)acrylic monomer unit A having an anionic group, (meth)acrylic monomer unit B having a cationic group, and (meth)acrylic monomer unit C other than (meth)acrylic monomer unit A and (meth)acrylic monomer unit B, the content of the inorganic ion scavenger is 0.1 to 50 parts by mass per 100 parts by mass of the thermosetting resin, and the content of the copolymer is 0.01 to 10 parts by mass per 100 parts by mass of the inorganic filler. (2) The resin composition according to (1), wherein the thermal conductivity of the inorganic filler is 20 W / m·K or more. (3) The resin composition according to (1) or (2), wherein the content of the inorganic filler is 30 to 70% by volume relative to the total volume of the resin composition. (4) The resin composition according to any one of (1) to (3), wherein the inorganic ion scavenger comprises at least one selected from the group consisting of Al, Mg, Bi, Zr, Sb, Sn, Ti, and Zn. (5) The resin composition according to any one of (1) to (4), wherein the average particle size of the inorganic ion scavenger is 0.05 to 10 μm. (6) The resin composition according to any one of (1) to (5), wherein the mass ratio of the inorganic ion scavenger to the copolymer is 0.001 to 10000. (7) A resin composition according to any one of (1) to (6), having a peak in the range of 2θ = 11 to 15° in X-ray diffraction measurements. (8) The resin composition according to any one of (1) to (7), wherein the thermosetting resin is an epoxy resin. (9) An insulating resin cured body which is a cured body of the resin composition described in any of (1) to (8). (10) A laminate comprising a first metal layer, an insulating layer disposed on one surface of the first metal layer, and a second metal layer disposed on the surface of the insulating layer opposite to the first metal layer, wherein the insulating layer is the insulating resin cured body described in (9). (11) A circuit board comprising a metal layer, an insulating layer disposed on one surface of the metal layer, and a metal circuit portion disposed on the surface of the insulating layer opposite to the metal layer, wherein the insulating layer is the insulating resin cured body described in (9). [Effects of the Invention]

[0009] The present invention provides a resin composition capable of forming an insulating layer having excellent insulating reliability against the application of a high DC voltage under high temperature (150°C) conditions. Furthermore, the present invention provides an insulating resin cured body which is a cured product of the resin composition, a laminate using the insulating resin cured body, and a circuit board. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing one embodiment of the laminate. [Figure 2] This is a cross-sectional view showing one embodiment of a circuit board. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below.

[0012] One embodiment of the present invention is a resin composition containing a thermosetting resin, an inorganic filler, a copolymer, and an inorganic ion scavenger.

[0013] Examples of thermosetting resins include silicone resins, epoxy resins, phenolic resins, cyanate resins, melamine resins, urea resins, thermosetting polyimide resins, and unsaturated polyester resins. The thermosetting resin may include epoxy resin. The thermosetting resin can be used individually or in combination of two or more types.

[0014] From the viewpoint of further improving insulation properties, the content of the thermosetting resin may be 10% by mass or more, 20% by mass or more, or 25% by mass or more, relative to the total mass of the resin composition. From the viewpoint of improving thermal conductivity, the content of the thermosetting resin may be 50% by mass or less, 40% by mass or less, or 30% by mass or less, relative to the total mass of the resin composition.

[0015] The inorganic filler may be, for example, a known inorganic filler used in applications where insulation and thermal conductivity are required (excluding those that fall under the category of inorganic ion scavengers described later). The inorganic filler may include, for example, one or more selected from the group consisting of aluminum oxide (alumina), silicon oxide, silicon nitride, boron nitride, aluminum nitride, and magnesium oxide. From the viewpoint of further improving insulation reliability in high humidity environments, it may also include one or more selected from the group consisting of aluminum oxide, silicon oxide, silicon nitride, boron nitride, and aluminum nitride, or one or more selected from the group consisting of aluminum oxide, boron nitride, and aluminum nitride.

[0016] The shape of the inorganic filler may be, for example, particulate, flaky, polygonal, etc. From the perspective of improving thermal conductivity, the average particle diameter of the inorganic filler may be 0.05 μm or more, 0.1 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. From the perspective of further improving insulation, it may be 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, or 40 μm or less. In this specification, the average particle diameter of the inorganic filler means the d50 diameter in the volume-based particle size distribution of the inorganic filler. The volume-based particle size distribution of the inorganic filler is measured by a laser diffraction particle size distribution measuring device.

[0017] The thermal conductivity of the inorganic filler may be 20 W / m·K or more, 50 W / m·K or more, 100 W / m·K or more, or 150 W / m·K or more, and may also be 35000 W / m·K or less, 2000 W / m·K or less, 600 W / m·K or less, 300 W / m·K or less, or 200 W / m·K or less.

[0018] The inorganic filler may contain two or more types of inorganic fillers having different average particle diameters from each other. For example, the inorganic filler may include a first inorganic filler having an average particle diameter of 25 μm or more and a second inorganic filler having an average particle diameter of 4 μm or less. According to such an inorganic filler, the second inorganic filler fills the gaps between the first inorganic fillers, increasing the packing density and contributing to the improvement of thermal conductivity.

[0019] The average particle diameter of the first inorganic filler may be 30 μm or more or 40 μm or more, and may also be 200 μm or less or 150 μm or less. The average particle diameter of the second inorganic filler may be 3.5 μm or less or 3 μm or less, and may also be 0.05 μm or more or 0.1 μm or more.

[0020] From the viewpoint of improving thermal conductivity, the content of the inorganic filler may be 30% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more based on the total mass of the resin composition. From the viewpoint of further improving insulation properties, the content of the inorganic filler may be 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less based on the total mass of the resin composition, and is preferably 65% by mass or less from the viewpoint of obtaining a metal-based substrate having even more excellent insulation reliability against high voltage in a high-temperature or high-temperature and high-humidity environment.

[0021] From the viewpoint of improving thermal conductivity, the content of the inorganic filler may be 20% by volume or more, 30% by volume or more, 40% by volume or more, 45% by volume or more, or 50% by volume or more based on the total volume of the resin composition. From the viewpoint of further improving insulation properties, the content of the inorganic filler may be 80% by volume or less, 70% by volume or less, 60% by volume or less, 55% by volume or less, or 50% by volume or less based on the total volume of the resin composition, and is preferably 55% by volume or less from the viewpoint of obtaining a metal-based substrate having even more excellent insulation reliability against high voltage in a high-temperature or high-temperature and high-humidity environment. The content of the inorganic filler may be 20 - 80% by volume or 30 - 70% by volume based on the total volume of the resin composition.

[0022] The copolymer has an anionic group-containing (meth)acrylic monomer unit A (hereinafter also referred to as "unit A", and the monomer giving unit A is also referred to as "monomer A"), a cationic group-containing (meth)acrylic monomer unit B (hereinafter also referred to as "unit B", and the monomer giving unit B is also referred to as "monomer B"), and a (meth)acrylic monomer unit C other than the (meth)acrylic monomer unit A and the (meth)acrylic monomer unit B (hereinafter also referred to as "unit C", and the monomer giving unit C is also referred to as "monomer C"). The copolymer may have a (meth)acrylic monomer unit (unit X) having both an anionic group and a cationic group. In this case, unit X is regarded as corresponding to both unit A and unit B. In other words, a copolymer having unit X is regarded as having both unit A and unit B.

[0023] In this specification, "monomer" means a monomer having polymerizable groups before polymerization. "Monomer unit" means a structural unit derived from the monomer that constitutes the copolymer. "(meth)acrylic monomer" means a monomer having a (meth)acryloyl group. "(meth)acrylic monomer" means acrylic monomers and their corresponding methacrylic monomers, and similar expressions such as "(meth)acryloyl group" have the same meaning.

[0024] The copolymer has one or more units A, B, and C. The copolymer may be a random copolymer or a block copolymer. Monomers A, B, and C may each be monomers having one (meth)acryloyl group (monofunctional (meth)acrylic monomers) or monomers having two or more (meth)acryloyl groups (polyfunctional (meth)acrylic monomers), and are preferably monofunctional (meth)acrylic monomers.

[0025] The anionic group possessed by unit A is, for example, one or more selected from the group consisting of a carboxyl group, a phosphoric acid group, a phenolic hydroxyl group, and a sulfonic acid group. From the viewpoint of further improving the dispersibility of the inorganic filler, the anionic group is preferably one or more selected from the group consisting of a carboxyl group, a phosphoric acid group, and a phenolic hydroxyl group.

[0026] Unit A preferably further comprises an electron-withdrawing group bonded to an anionic group, from the viewpoint of further improving the dispersibility of the inorganic filler. The electron-withdrawing group has the effect of stabilizing the anion of the anionic group. Examples of electron-withdrawing groups include halogen groups (also called halogeno groups). Examples of anionic groups to which electron-withdrawing groups are bonded include a group in which a halogen group is bonded to the carbon atom at the α position of a carboxyl group.

[0027] Unit A does not need to have an electron-donating group bonded to the anionic group. Electron-donating groups can destabilize the anion of the anionic group. An example of an electron-donating group is the methyl group.

[0028] Examples of monomer A include acrylic acid, methacrylic acid, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypolyoxypropylene glycol monomethacrylate, phosphoric acid-modified epoxy acrylate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 4-hydroxyphenyl acrylate, 4-hydroxyphenyl meacrylate, 2-methacryloyloxyethyl succinic acid, and 2-acrylamido-2-methylpropanesulfonic acid. From the viewpoint of further improving the dispersibility of the inorganic filler, monomer A is preferably one or more selected from the group consisting of acrylic acid, 2-methacryloyloxyethyl phosphate, 4-hydroxyphenyl meacrylate, and 2-acrylamido-2-methylpropanesulfonic acid, and more preferably acrylic acid.

[0029] The cationic group possessed by unit B is, for example, one or more selected from the group consisting of primary amino groups, secondary amino groups, tertiary amino groups, and quaternary ammonium bases. From the viewpoint of further improving the dispersibility of the inorganic filler, the cationic group is preferably a tertiary amino group.

[0030] Unit B preferably further comprises an electron-donating group bonded to a cationic group, from the viewpoint of further improving the dispersibility of the inorganic filler. The electron-donating group has the effect of stabilizing the cation of the cationic group. An example of an electron-donating group is a methyl group. An example of a cationic group to which an electron-donating group is bonded is a group in which a methyl group is bonded to the carbon atom at the α position of an amino group.

[0031] Unit B does not need to have an electron-withdrawing group bonded to a cationic group. Electron-withdrawing groups can destabilize the cation of the cationic group. An example of an electron-withdrawing group is a carboxyl group.

[0032] Examples of monomer B include 1-aminoethyl acrylate, 1-aminopropyl acrylate, 1-aminoethyl methacrylate, 1-aminopropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, t-butylaminoethyl (meth)acrylate, dimethylaminoethyl methacrylate quaternary salt, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and dimethylaminoethyl acrylate benzyl chloride quaternary salt. From the viewpoint of further improving the dispersibility of the inorganic filler, monomer B is preferably one or more selected from the group consisting of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and more preferably 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate.

[0033] Unit C is a (meth)acrylic monomer that does not contain either a cationic or anionic group. In addition to the (meth)acryloyl group, unit C may have an amphiphilic group, a hydrophobic group, or a hydrophilic group. An example of an amphiphilic group is an oxyalkylene group. An example of a hydrophobic group is a siloxane group and a hydrocarbon group. An example of a hydrophilic group is a phosphate ester group. Note that the hydrocarbon group referred to here does not include the methyl group that constitutes the methacryloyl group (the same applies to the hydrocarbon group in unit C below).

[0034] Unit C has one or more selected from the group consisting of oxyalkylene groups, siloxane groups, and hydrocarbon groups, and more preferably has one or more selected from the group consisting of siloxane groups and hydrocarbon groups, from the viewpoint of affinity or compatibility between the copolymer and the resin when the resin composition further contains a resin.

[0035] Examples of (meth)acrylic monomers having an oxyalkylene group include ethoxycarbonylmethyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, phenol (ethylene oxide 2 molar modified) (meth)acrylate, phenol (ethylene oxide 4 molar modified) (meth)acrylate, paracumylphenol ethylene oxide modified (meth)acrylate, nonylphenol ethylene oxide modified (meth)acrylate, nonylphenol (ethylene oxide 4 molar modified) (meth)acrylate, nonylphenol (ethylene oxide 8 molar modified) (meth)acrylate, nonylphenol (propylene oxide 2.5 molar modified) acrylate, 2-ethylhexylcarbitol (meth)acrylate, ethylene oxide modified phthalic acid (meth)acrylate, ethylene oxide modified succinic acid (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate.

[0036] Examples of (meth)acrylic monomers having a siloxane group include α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane. Examples of (meth)acrylic monomers having a hydrocarbon group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, and methoxylated cyclodecatriene (meth)acrylate.

[0037] Examples of (meth)acrylic monomers having a phosphate ester group include (meth)acryloyloxyethyldialkyl phosphates.

[0038] Monomer C may also be, for example, a (meth)acrylic monomer having a hydroxyl group. Examples of (meth)acrylic monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate.

[0039] Monomer C may be, for example, a (meth)acrylic monomer having an amide bond. Examples of (meth)acrylic monomers having an amide bond include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, diacetone(meth)acrylamide, and acryloylmorpholine.

[0040] Monomer C may be, for example, a polyfunctional (meth)acrylic monomer. Examples of polyfunctional (meth)acrylic monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexadiol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, 2-ethyl-2-butyl-propanediol (meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, 2-(1,2-cyclohexacarboxyimide)ethyl (meth)acrylate, hexanediol di(meth)acrylate, and polyfunctional (meth)acrylates having a bisphenol structure.

[0041] The content of unit A may be 0.03 mol% or more, 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 2 mol% or more, 3 mol% or more, 4 mol% or more, or 5 mol% or more, based on 100 mol% of the total of unit A, unit B, and unit C (in other words, the total of all monomer units in the copolymer; the same applies hereinafter), or it may be 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 5 mol% or less. A unit A content of 0.03 mol% or more tends to improve the dispersibility of the inorganic filler. A unit A content of 70 mol% or less tends to reduce the viscosity of the resin composition and improve the handling properties of the resin composition.

[0042] The content of unit B may be 0.02 mol% or more, 0.05 mol% or more, 0.07 mol% or more, or 0.1 mol% or more, relative to 100 mol% of the total of units A, B, and C, and may be 20 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, 1 mol% or less, 0.5 mol% or less, or 0.1 mol% or less. A unit B content of 0.02 mol% or more tends to result in better affinity of the copolymer to inorganic fillers. A unit B content of 20 mol% or less tends to further reduce the viscosity of the resin composition and further improve the handling properties of the resin composition.

[0043] The content of unit C may be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 92 mol% or more, or 94 mol% or more, relative to 100 mol% of the total of units A, B, and C, and may be 99.8 mol% or less, 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, or 95 mol% or less. When the content of unit C is 10 mol% or more, the viscosity of the resin composition tends to decrease further and the handling properties of the resin composition tend to improve further. When the content of unit C is 99.8 mol% or less, the affinity of the copolymer to the inorganic filler tends to be better.

[0044] The total content of unit A and unit B may be 0.05 mol% or more, 0.2 mol% or more, 1 mol% or more, 2 mol% or more, 3 mol% or more, 4 mol% or more, or 5 mol% or more, relative to 100 mol% of the total of unit A, unit B, and unit C, and may be 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, 8 mol% or less, or 6 mol% or less. When the total content of unit A and unit B is 0.05 mol% or more, the dispersibility of the inorganic filler tends to be further improved. When the total content of unit A and unit B is 90 mol% or less, the handling properties of the resin composition tend to be further improved.

[0045] The molar ratio of unit A to unit B (unit A / unit B) may be 0.01 or greater, 0.9 or greater, 1 or greater, 5 or greater, 10 or greater, 20 or greater, 30 or greater, 40 or greater, or 50 or greater, and may also be 200 or less, 150 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, or 10 or less. When the molar ratio of unit A to unit B is within the above range, the dispersibility of the inorganic filler tends to improve.

[0046] The weight-average molecular weight of the copolymer may be 1,000 or more, 5,000 or more, 7,000 or more, 10,000 or more, 20,000 or more, 30,000 or more, 40,000 or more, or 50,000 or more, and may also be 1,000,000 or less, 500,000 or less, 300,000 or less, 100,000 or less, 90,000 or less, 80,000 or less, 70,000 or less, or 60,000 or less. By having a weight-average molecular weight of 1,000 or more of the copolymer, the dispersibility of the inorganic filler can be maintained and the hardness increase of the resin composition can be suppressed even when the resin composition is stored for a long time in a high-temperature environment. In addition, the shape retention of the resin composition is improved, and when applied to sloped or vertical surfaces, slippage and dripping of the resin composition are suppressed. When the weight-average molecular weight of the copolymer is 1,000,000 or less, the viscosity of the resin composition tends to decrease further, and the handling properties of the resin composition tend to improve. The weight-average molecular weight of the copolymer is determined as the weight-average molecular weight on a standard polystyrene basis using the GPC (gel permeation chromatography) method.

[0047] Copolymers are obtained by polymerizing monomers A, B, and C using known polymerization methods. Examples of polymerization methods include radical polymerization and anionic polymerization. Radical polymerization is preferred as the polymerization method.

[0048] The polymerization initiator used in radical polymerization may be a thermal polymerization initiator or a photopolymerization initiator. Examples of thermal polymerization initiators include azo compounds such as azobisisobutyronitrile; and organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, and di-tert-butyl peroxide. Examples of photopolymerization initiators include benzoin derivatives. The polymerization initiator may also be a known polymerization initiator used in living radical polymerization such as ATRP and RAFT.

[0049] Polymerization conditions can be adjusted as appropriate depending on the type of monomer, polymerization initiator, etc. If the copolymer is a random copolymer, the monomers may be mixed beforehand before polymerization. If the copolymer is a block copolymer, the monomers may be added sequentially to the polymerization system.

[0050] The copolymer content is 0.01 to 10 parts by mass per 100 parts by mass of inorganic filler. By having a copolymer content within this range, a resin composition is obtained that can form an insulating layer with excellent insulating reliability against the application of high DC voltage under high temperature (150°C) conditions. The copolymer content may be 0.05 parts by mass or more, 0.1 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more per 100 parts by mass of inorganic filler, and may also be 9 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, 6 parts by mass or less, 5 parts by mass or less, or 4 parts by mass or less.

[0051] The copolymer content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 2.5% by mass or more, relative to the total mass of the resin composition, and may also be 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, or 3% by mass or less.

[0052] An inorganic ion scavenger is an inorganic material that has the function of capturing at least one of a cation and an anion (has ion-scavenging properties). In this specification, "ion-scavenging properties" mean the property of adsorbing the ion to be captured onto the surface of the inorganic material, or the property of introducing the ion to be captured into the structure of the inorganic material through ion exchange between ions in the structure of the inorganic material and the ion to be captured. Examples of ions to be captured by an inorganic ion scavenger include cations such as Na ions, Cu ions, and Ag ions; and anions such as Cl ions and Br ions.

[0053] The inorganic ion scavenger may contain, for example, at least one element selected from the group consisting of Al, Mg, Bi, Zr, Sb, Sn, Ti, and Zn, or it may contain at least one element selected from the group consisting of Al, Mg, Bi, Zr, Sb, and Zn. The inorganic ion scavenger may also be, for example, an oxide, acid chloride, or hydrate thereof containing at least one of these metal elements. The inorganic ion scavenger may contain two or more of these metal elements.

[0054] Examples of inorganic ion scavenging agents include anion exchangers that scavenge anions, cation exchangers that scavenge cations, and dual ion exchangers that scavenge both anions and cations. Inorganic ion scavenging agents may be used individually or in combination of two or more types. For example, a dual ion exchanger may be a mixture of an anion exchanger and a cation exchanger.

[0055] Examples of anion exchangers include inorganic materials containing at least one selected from the group consisting of Al, Mg, Bi, Zr, and Zn. Specific examples of anion exchangers include IXE-500 (Bi-based), IXE-530 (Bi-based), IXE-550 (Bi-based), IXE-700 (Mg, Al-based), IXE-700F (Mg, Al-based), IXE-770 (Mg, Al-based), IXE-770D (Mg, Al-based), IXE-702 (Al-based), IXE-800 (Zr-based), and IXE-1000 (Zn-based) (all manufactured by Toagosei Co., Ltd.).

[0056] Examples of cation exchangers include inorganic materials containing at least one selected from the group consisting of Zr, Sn, and Ti. Specific examples of cation exchangers include IXE-100 (Zr-based), IXE-200 (Sn-based), IXE-300 (Sb-based), and IXE-400 (Ti-based) (all manufactured by Toagosei Co., Ltd.).

[0057] Examples of ion exchangers include inorganic materials containing at least one selected from the group consisting of Al, Mg, Bi, Zr, and Sb. Specific examples of ion exchangers include IXE-1320 (Mg, Al system), IXE-600 (Sb, Bi system), IXE-633 (Bi system), IXE-680 (Bi system), IXE-6107 (Zr, Bi system), IXE-6136 (Zr, Bi system), IXEPLAS-A1 (Zr, Mg, Al system), IXEPLAS-A2 (Zr, Mg, Al system), and IXEPLAS-B1 (Zr, Bi system) (all manufactured by Toagosei Co., Ltd.).

[0058] The average particle size of the inorganic ion scavenger may be 0.05 μm or larger, 0.1 μm or larger, 0.15 μm or larger, 0.2 μm or larger, 0.3 μm or larger, 0.4 μm or larger, or 0.5 μm or larger, and may be 10 μm or smaller, 5 μm or smaller, 3 μm or smaller, 2 μm or smaller, 1.5 μm or smaller, or 1 μm or smaller. The average particle size of the inorganic ion scavenger may be between 0.05 and 10 μm. The average particle size of the inorganic ion scavenger can be measured by laser diffraction / scattering.

[0059] The content of the inorganic ion scavenger, which includes at least one selected from the group consisting of Al, Mg, Bi, Zr, Sb, and Zn, may be 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total mass of the inorganic ion scavenger. The content of the inorganic ion scavenger, which includes at least one selected from the group consisting of Al, Mg, Bi, Zr, Sb, and Zn, may be substantially 100% by mass, based on the total mass of the inorganic ion scavenger.

[0060] The inorganic ion scavenger content is 0.1 to 50 parts by mass per 100 parts by mass of the total of the thermosetting resin and copolymer. From the viewpoint of obtaining a resin composition capable of forming an insulating layer with better insulating reliability against the application of high DC voltage under high temperature (150°C) conditions, the inorganic ion scavenger content may be 0.3 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more per 100 parts by mass of the total of the thermosetting resin and copolymer, or it may be 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less.

[0061] The inorganic ion scavenger content may be 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 1.2% by mass or more, or 1.4% by mass or more, relative to the total mass of the resin composition, from the viewpoint of obtaining a resin composition capable of forming an insulating layer with better insulating reliability against the application of high DC voltage under high temperature (150°C) conditions. It may also be 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, or 4% by mass or less.

[0062] The mass ratio of the inorganic ion scavenger to the copolymer (mass-based content of inorganic ion scavenger / mass-based content of copolymer) may be 0.005 or more, 0.01 or more, or 0.05 or more, or 1000 or less, 100 or less, or 50 or less, from the viewpoint of obtaining a resin composition capable of forming an insulating layer with better insulating reliability against the application of high DC voltage under high temperature conditions (150°C). The mass ratio of the inorganic ion scavenger to the copolymer may be 25 or less, 10 or less, 5 or less, or 3 or less. The mass ratio of the inorganic ion scavenger to the copolymer may be 0.001 to 10000.

[0063] The resin composition may further contain a curing agent for curing the thermosetting resin. The curing agent is appropriately selected depending on the type of thermosetting resin. For example, when the thermosetting resin is an epoxy resin, examples of curing agents include amine-based resins, acid anhydride-based resins, and phenol-based resins. The curing agent may be used alone or in combination of two or more types.

[0064] The curing agent content may be 1% by mass or more, or 3% by mass or more, or 10% by mass or less, or 5% by mass or less, based on the total mass of the resin composition.

[0065] The resin composition may further contain other components. Examples of other components include curing accelerators, coupling agents, leveling agents, antioxidants, defoamers, wetting agents, dispersants, and stabilizers.

[0066] The resin composition is obtained by mixing a thermosetting resin, an inorganic filler, a copolymer, and an inorganic ion scavenger (and, if necessary, a curing agent and other components). Mixing may be carried out using, for example, a planetary agitator, a universal mixer, a kneader, a hybrid mixer, etc.

[0067] The resin composition may have a peak in the range of 2θ = 11 to 15° in X-ray diffraction measurements. The peak position of the resin composition in X-ray diffraction measurements can be confirmed, for example, by preparing a cured body of the resin composition and performing X-ray diffraction measurements on the cured body. The resin composition may have a peak at the position of 2θ = 11.5 to 14.5 or 11.8 to 14 in X-ray diffraction measurements.

[0068] The resin compositions described above can be used, for example, after curing. That is, one embodiment of the present invention is a cured body (insulating resin cured body) of the above-described resin composition. The cured body may be in a semi-cured state (Stage B) or a fully cured state (Stage C).

[0069] The cured body can be obtained, for example, by heat-treating and curing the resin composition described above. The heat treatment conditions (heating temperature, heating time, etc.) are set appropriately according to the type of resin and curing agent, the desired curing state, etc. The heat treatment may be carried out in one stage or in two stages.

[0070] The cured body may be in the form of a sheet, for example. A sheet-shaped cured body can be obtained, for example, by applying the above-described resin composition onto a substrate and heating (and pressurizing as necessary). The sheet-shaped cured body may be a B-stage sheet in a semi-cured state, or a C-stage sheet in a fully cured state.

[0071] The resin composition and its cured product described above are suitably used for forming an insulating layer on a metal-based substrate. In other words, the resin composition and its cured product can also be referred to as a resin composition for metal-based substrates and a cured product for metal-based substrates, respectively.

[0072] Figure 1 is a schematic cross-sectional view showing one embodiment of the laminate. As shown in Figure 1, the laminate 10A according to one embodiment comprises a first metal layer 1A, an insulating layer (cured resin composition as described above) 2 disposed on one surface of the first metal layer, and a second metal layer 3A disposed on the surface of the insulating layer 2 opposite to the first metal layer. In this laminate 10A, the first metal layer 1A and the second metal layer 3A are separated by the insulating layer 2 and maintain an electrically insulated state from each other.

[0073] Examples of metal materials constituting the first metal layer 1A include aluminum, aluminum alloys, copper, copper alloys, iron, and stainless steel. The first metal layer 1A may be composed of one type of metal material, or it may be composed of two or more types of metal materials. The first metal layer 1A may have a single-layer structure or a multi-layer structure.

[0074] Examples of metal materials that constitute the second metal layer 3A include copper, aluminum, and nickel. The second metal layer 3A may be composed of one metal material, or it may be composed of two or more metal materials. The second metal layer 3A may have a single-layer structure or a multi-layer structure. In Figure 1, the second metal layer 3A is arranged over substantially the entire surface of the insulating layer 2, but the second metal layer may be arranged over only a part of the insulating layer 2.

[0075] The thickness of the first metal layer 1A may be, for example, 0.5 mm or more, or 3 mm or less. The thickness of the insulating layer 2 may be, for example, 50 μm or more, or 300 μm or less. The thickness of the second metal layer 3A may be, for example, 5 μm or more, or 1 mm or less.

[0076] Figure 2 is a schematic cross-sectional view showing one embodiment of a circuit board. As shown in Figure 2, the circuit board 10B according to one embodiment comprises a metal layer 1B, an insulating layer (a cured body of the resin composition described above) 2 disposed on one surface of the metal layer 1B, and a metal circuit portion 3B disposed on the surface of the insulating layer 2 opposite to the metal layer 1B. In this circuit board 10B, the metal circuit portion 3B is, for example, a circuit processed into a predetermined pattern (e.g., etched).

[0077] The metal material constituting the metal layer 1B is the same as the metal material constituting the first metal layer 1A described above. The metal material constituting the metal circuit portion 3B is the same as the metal material constituting the second metal layer 3A described above.

[0078] The thickness of the metal layer 1B may be, for example, 0.5 mm or more, or 3 mm or less. The thickness of the insulating layer 2 may be, for example, 50 μm or more, or 300 μm or less. The thickness of the metal circuit portion 3B may be, for example, 5 μm or more, or 1 mm or less. [Examples]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0080] <Synthesis of copolymers> The monomers used in the synthesis of the copolymers in the examples are shown below. (Anionic group-containing (meth)acrylic monomer A) • Acrylic acid (manufactured by Toagosei Co., Ltd.) ((meth)acrylic monomer B having a cationic group) • 1,2,2,6,6-Pentamethyl-4-Piperidyl Methacrylate (ADEKA Corporation's "ADEKA Stab LA-82") ((meth)acrylic monomer C) • Benzyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd. as "Light Ester BZ")

[0081] First, 100 parts by mass of a (meth)acrylic monomer consisting of 5 mol% acrylic acid, 0.1 mol% 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and 94.9 mol% benzyl methacrylate was added to an autoclave equipped with a stirrer. Next, 0.5 parts by mass of azobisisobutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) as an initiator (relative to 100 parts by mass of the total (meth)acrylic monomer) and 1000 parts by mass of a mixed solution of toluene (reagent grade) and 2-propanol (reagent grade) as a solvent (toluene:2-propanol = 7:3 (volume ratio)) were added, and the autoclave was purged with nitrogen. After that, the autoclave was heated in an oil bath at 65°C for 20 hours to carry out radical polymerization. After polymerization was complete, the copolymer was obtained by degassing under reduced pressure at 120°C for 1 hour.

[0082] Gas chromatography analysis revealed that the polymerization rate relative to 100% of the monomer input was over 98%. Therefore, it was estimated that the ratio of each monomer unit in the copolymer was approximately the same as the input ratio of the monomers.

[0083] Furthermore, the weight-average molecular weight of the obtained copolymer 1 was determined as the weight-average molecular weight on a standard polystyrene basis using GPC (gel permeation chromatography). The measurement conditions were as follows. High-speed GPC system: Tosoh Corporation's "HLC-8020" Columns: One 6.0mm ID x 4.0cm column of Tosoh Corporation's "TSK guardcolumn MP (xL)" and two 7.8mm ID x 30.0cm columns of Tosoh Corporation's "TSK-GELMULTIPOREHXL-M" (16,000 theoretical plates), for a total of three columns (32,000 theoretical plates in total). Developing solvent: tetrahydrofuran Detector: RI (Differential Refractive Index Meter)

[0084] <Preparation of resin composition> (Example 1) 27.9% by mass of naphthalene-type epoxy resin HP-4032D (manufactured by DIC Corporation) as the thermosetting resin and 3.5% by mass of phenol novolac resin VH-4150 (manufactured by DIC Corporation) as the curing agent were stirred at 170°C to dissolve the curing agent in the thermosetting resin. A resin composition was prepared by stirring and mixing a resin with a dissolved curing agent, 64.4% by mass (50 vol%) of boron nitride filler (manufactured by Denka Co., Ltd., average particle size 40 μm, thermal conductivity 150 W / m·K) and 2.6% by mass (4 pf) of copolymer as inorganic fillers, 1.4% by mass (4.5 phr) of inorganic ion scavenging agent 1 (IXEPLAS-A1 (Zr, Mg, Al-based), average particle size 0.5 μm, manufactured by Toagosei Co., Ltd.) as an inorganic ion scavenging agent, and 0.2% by mass of 1B2PZ (manufactured by Shikoku Chemicals, Inc.) as a curing accelerator in a planetary mixer for 15 minutes.

[0085] <Preparation of hardened body> The obtained resin composition was applied to a polyethylene terephthalate (PET) film with a thickness of 0.038 mm so that the thickness after curing would be 0.20 mm, and then heated and dried at 100°C for 50 minutes to produce a semi-cured body (a sheet in the B stage).

[0086] <Fabrication of metal-based circuit boards> The prepared cured body (sheet in B-stage state) was peeled from the PET film and placed on the roughened surface of a metal plate (2.0 mm thick copper plate). The roughened surface of a metal foil (0.5 mm thick copper foil) was then placed on top of the cured body, and the material was heated and cured at 180°C for 410 minutes while applying a surface pressure of 10 MPa using a press machine.

[0087] Next, after masking the predetermined areas with etching resist, the copper foil was etched using a sulfuric acid-hydrogen peroxide mixed solution as the etching solution. After removing the etching resist and washing and drying, a metal-based circuit board having a 20 mm diameter circular electrode (copper foil) was obtained.

[0088] (Example 2) A resin composition, cured body, and metal-based circuit board were prepared in the same manner as in Example 1, except that inorganic ion scavenging agent 2 (IXEPLAS-A2 (Zr, Mg, Al-based), average particle size 0.2 μm, manufactured by Toagosei Co., Ltd.) was used as the inorganic ion scavenging agent.

[0089] (Example 3) Except for using inorganic ion scavenger 3 (IXEPLAS-B1 (Zr, Bi-based), average particle size 0.4 μm, manufactured by Toagosei Co., Ltd.) as the inorganic ion scavenger, a resin composition, a cured body, and a metal-based circuit board were prepared by the same method as in Example 1.

[0090] (Example 4) A resin composition, cured body, and metal-based circuit board were prepared in the same manner as in Example 1, except that an inorganic ion scavenger 4 (IXE-700F (Mg, Al-based), average particle size 1.5 μm, manufactured by Toagosei Co., Ltd.) was used as the inorganic ion scavenger.

[0091] (Example 5) A resin composition, a cured body, and a metal-based circuit board were prepared in the same manner as in Example 1, except that an inorganic ion scavenger 5 (IXE-550 (Bi-based), average particle size 1.5 μm, manufactured by Toagosei Co., Ltd.) was used as the inorganic ion scavenger.

[0092] (Example 6) Except for using inorganic ion scavenger 6 (IXE-100 (Zr-based), average particle size 1.0 μm, manufactured by Toagosei Co., Ltd.) as the inorganic ion scavenger, a resin composition, a cured body, and a metal-based circuit board were prepared by the same method as in Example 1.

[0093] (Example 7) Except for using inorganic ion scavenger 7 (IXE-600 (Sb, Bi-based), average particle size 1.0 μm, manufactured by Toagosei Co., Ltd.) as the inorganic ion scavenger, a resin composition, a cured body, and a metal-based circuit board were prepared by the same method as in Example 1.

[0094] (Example 8) A resin composition, a cured body, and a metal-based circuit board were prepared in the same manner as in Example 1, except that an inorganic ion scavenger 8 (IXE-6107 (Zr, Bi-based), average particle size 1.5 μm, manufactured by Toagosei Co., Ltd.) was used as the inorganic ion scavenger.

[0095] (Examples 9-15) Resin compositions, cured bodies, and metal-based circuit boards were prepared in the same manner as in Example 3, except that the amount of inorganic ion scavenger or copolymer added was changed as shown in Tables 2 and 3.

[0096] (Comparative Examples 1 and 2) Except for changing the amount of inorganic ion scavenging agent added as shown in Table 4, the resin composition, cured body, and metal-based circuit board were prepared in the same manner as in Example 3.

[0097] (Comparative Examples 3 and 4) The resin composition, cured body, and metal-based circuit board were prepared in the same manner as in Example 2, except that the amount of copolymer added was changed as shown in Table 4.

[0098] [XRD peak measurement] X-ray diffraction measurements were performed on the cured bodies prepared in each example and comparative example using the Rigaku MiniFlexII X-ray diffractometer manufactured by Rigaku Corporation. The positions of the XRD peaks detected in the range of 2θ = 11 to 15° are shown in Tables 1 to 4.

[0099] [Reliability evaluation using high-temperature, high-pressure bias testing (Vt)] A high-temperature, high-voltage bias test (Vt) was performed on the obtained metal-based substrates under test conditions of applying a DC voltage of 10kV between the metal foil and metal plate at a 150°C environment, measuring the time until dielectric breakdown. The time until dielectric breakdown was defined as the time from the start of voltage application until the leakage current value measured by the withstand voltage tester exceeded 10mA.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] [Table 4] [Explanation of Symbols]

[0104] 1A...First metal layer, 1B...Metal layer, 2...Insulating layer, 3A...Second metal layer, 3B...Metal circuit section, 10A...Laminate, 10B...Circuit board.

Claims

1. A resin composition containing a thermosetting resin, an inorganic filler, a copolymer, and an inorganic ion scavenger, The copolymer comprises an anionic group (meth)acrylic monomer unit A, a cationic group (meth)acrylic monomer unit B, and (meth)acrylic monomer units C other than the (meth)acrylic monomer unit A and the (meth)acrylic monomer unit B. The inorganic filler content is 30 to 70% by volume relative to the total volume of the resin composition. The amount of the inorganic ion scavenger is 0.5 to 20 parts by mass per 100 parts by mass of the total of the thermosetting resin and the copolymer. The copolymer content is 3 to 5 parts by mass per 100 parts by mass of the inorganic filler. A resin composition in which the mass ratio of the inorganic ion scavenger to the copolymer is 0.37 to 1.

22.

2. The resin composition according to claim 1, wherein the thermal conductivity of the inorganic filler is 20 W / m·K or more.

3. The resin composition according to claim 1, wherein the inorganic ion scavenger comprises at least one selected from the group consisting of Al, Mg, Bi, Zr, Sb, Sn, Ti, and Zn.

4. The resin composition according to claim 1, wherein the average particle size of the inorganic ion scavenger is 0.05 to 10 μm.

5. The resin composition according to claim 1, having a peak in the range of 2θ = 11 to 15° in X-ray diffraction measurements.

6. The resin composition according to claim 1, wherein the thermosetting resin is an epoxy resin.

7. An insulating resin cured body, which is a cured body of the resin composition described in claim 1.

8. The device comprises a first metal layer, an insulating layer disposed on one surface of the first metal layer, and a second metal layer disposed on the surface of the insulating layer opposite to the first metal layer. A laminate in which the insulating layer is the insulating resin cured body described in claim 7.

9. It comprises a metal layer, an insulating layer disposed on one surface of the metal layer, and a metal circuit portion disposed on the surface of the insulating layer opposite to the metal layer, A circuit board wherein the insulating layer is the insulating resin cured body described in claim 7.

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