Resin sheet

Abstract

To provide a resin sheet or the like which has low melt viscosity and can give a cured product having excellent embedding properties, high thermal conductivity, and high adhesion before and after a HAST test.SOLUTION: The resin sheet includes a support and a resin composition layer provided on the support. The resin composition layer contains: (A) an epoxy resin; (B) a silane coupling agent which has epoxy groups and a trialkoxysilyl group, the number of the epoxy groups being 2 or more; and (C) an inorganic filler. The thermal conductivity of the component (C) is 20 W / mK or more. The water absorption rate of a cured product obtained by heating the resin composition layer at 200°C for 90 minutes is 0.2 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin sheet. Further, the present invention relates to a circuit board, a semiconductor chip package, a semiconductor device, and an electronic member obtained by using the resin sheet.

Background Art

[0002] In recent years, miniaturization and high functionality of electronic devices have progressed, and the mounting density of semiconductor elements on printed wiring boards has tended to increase. Along with the high functionality of the mounted semiconductor elements, a technique for efficiently dissipating heat generated by the semiconductor elements is required.

[0003] For example, Patent Document 1 discloses that heat dissipation is achieved by using, for a circuit board, an insulating layer obtained by curing a resin composition containing a resin and alumina that satisfies predetermined requirements.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, due to an increase in the amount of heat generated by semiconductor elements in printed wiring boards, it has been required to further improve the thermal conductivity of the insulating layer. Further, with the miniaturization of electronic devices, miniaturization of printed wiring boards has also been required. For this reason, a method using an inorganic filler such as alumina having a small average particle size can be considered, but when an inorganic filler having a small average particle size is contained, the embedding property may be poor. Further, when wiring having pads is embedded in such an insulating layer, the adhesion between the wiring after an accelerated environmental test (HAST test) in a high temperature and high humidity environment and the pads may decrease at the pad portions.

[0006] The present invention was devised in view of the above problems, and provides a resin sheet that is excellent in embeddability, has a high thermal conductivity, and can obtain a cured product with high adhesion before and after the HAST test; a circuit board, a semiconductor chip package, a semiconductor device, and an electronic member including an insulating layer formed of a cured product of the resin composition layer of the resin sheet.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that by incorporating a specific silane coupling agent into the resin composition layer and adjusting the components (A) to (C) so that the water absorption rate of the cured product falls within a specific range and incorporating them into the resin composition layer, a cured product excellent in embeddability, having a high thermal conductivity, and having high adhesion before and after the HAST test can be obtained, and thus the present invention has been completed.

[0008] That is, the present invention includes the following. [1] A resin sheet including a support and a resin composition layer provided on the support, wherein the resin composition layer (A) an epoxy resin, (B) a silane coupling agent having an epoxy group and a trialkoxysilyl group and having two or more epoxy groups, and (C) an inorganic filler, and the thermal conductivity of the component (C) is 20 W / mK or more, and the water absorption rate of the cured product obtained by heating the resin composition layer at 200 °C for 90 minutes is 0.2 mass% or less. [2] The resin sheet according to [1], wherein the component (B) is included as a surface treatment agent for the component (C). [3] The resin sheet according to [1] or [2], wherein the content of the component (C) is 70 mass% or more when the non-volatile components in the resin composition layer are 100 mass%. [4] The resin sheet according to any one of [1] to [3], further including (D) an elastomer. [5] The resin sheet according to any one of [1] to [4], wherein the component (C) includes alumina. [6] The resin sheet according to any one of [1] to [5], wherein the (B) component contains a triethoxysilyl group. [7] A circuit board including an insulating layer formed by a cured product of the resin composition layer of the resin sheet according to any one of [1] to [6]. [8] A semiconductor chip package including a cured product of the resin composition layer of the resin sheet according to any one of [1] to [6]. [9] A semiconductor device including the semiconductor chip package according to [8].

[10] An electronic component having an electronic component, a cured product of the resin composition layer of the resin sheet according to any one of [1] to [6] provided on the electronic component, and a heat radiating member mounted on the cured product. [Advantages of the Invention]

[0009] According to the present invention, a resin sheet capable of obtaining a cured product excellent in embeddability, having a high thermal conductivity, and having high adhesion before and after a HAST test; a circuit board, a semiconductor chip package, a semiconductor device, and an electronic component including an insulating layer formed by a cured product of the resin composition layer of the resin sheet can be provided. [Embodiments for Carrying Out the Invention]

[0010] Hereinafter, the present invention will be described with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0011] [Resin Sheet] The resin sheet of the present invention includes a support and a resin composition layer provided on the support, and the resin composition layer contains (A) an epoxy resin, (B) a silane coupling agent having an epoxy group and a trialkoxysilyl group and having 2 or more epoxy groups, and (C) an inorganic filler. The thermal conductivity of the component (C) is 20 W / mK or more, and the water absorption of the cured product obtained by heating the resin composition layer at 200°C for 90 minutes is 0.2% by mass or less. According to such a resin sheet, it is possible to obtain a cured product that is excellent in embeddability, has a high thermal conductivity, and has high adhesion before and after the HAST test. Further, the resin composition layer of the resin sheet usually has a low melt viscosity and excellent storage stability, so that a cured product having a low melt viscosity even after being stored in a refrigerator for 2 weeks and excellent embeddability even after being stored in a refrigerator for 2 weeks can also be obtained. Hereinafter, each layer constituting the resin sheet will be described in detail.

[0012] <Support> The resin sheet includes a support. Examples of the support include a film made of a plastic material, a metal foil, and a release paper, and a film made of a plastic material and a metal foil are preferred.

[0013] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"); polycarbonate (hereinafter sometimes abbreviated as "PC"); acrylic polymers such as polymethyl methacrylate (hereinafter sometimes abbreviated as "PMMA"); cyclic polyolefin; triacetyl cellulose (hereinafter sometimes abbreviated as "TAC"); polyethersulfide (hereinafter sometimes abbreviated as "PES"); polyether ketone; polyimide; and the like. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0014] When using a metal foil as the support, examples of the metal foil include copper foil, aluminum foil, etc. Among them, copper foil is preferred. As the copper foil, a foil made of single metal copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0015] The support may be subjected to treatments such as mat treatment, corona treatment, antistatic treatment, etc. on the surface that joins the resin composition layer.

[0016] Also, as the support, a support with a release layer having a release layer on the surface that joins the resin composition layer may be used. Examples of the release agent used for the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resin, polyolefin resin, urethane resin, and silicone resin. Examples of commercially available products of the release agent include "SK-1", "AL-5", "AL-7", etc. manufactured by Lintec Corporation, which are alkyd resin-based release agents. Also, examples of the support with a release layer include "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipile" manufactured by Unitika Ltd.; etc.

[0017] The thickness of the support is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When using a support with a release layer, it is preferable that the total thickness of the support with a release layer is within the above range.

[0018] <Resin composition layer> In the resin sheet of the present invention, the resin composition layer provided on the support contains (A) an epoxy resin, (B) a silane coupling agent having an epoxy group and a trialkoxysilyl group and having 2 or more epoxy groups, and (C) an inorganic filler, the thermal conductivity of the (C) component is 20 W / mK or more, and the water absorption rate of the cured product obtained by heating the resin composition layer at 200 °C for 90 minutes is 0.2 mass% or less.

[0019] The resin composition layer contains components (A) to (C) in combination so that the water absorption rate of its cured product is 0.2% by mass or less. As a result of intensive studies by the present inventors, it has been found that the water absorption rate is correlated with the adhesion between the insulating layer and the conductor layer. By containing components (A) to (C) in combination so that the water absorption rate of the cured product is 0.2% by mass or less, excellent embedability, high thermal conductivity, and improvement of adhesion after the HAST test can be achieved.

[0020] From the viewpoint of improving the adhesion after the HAST test, the water absorption rate (% by mass) of the cured product of the resin composition layer is 0.2% by mass or less, preferably 0.18% by mass or less, more preferably 0.15% by mass or less. The lower limit is not particularly limited, and it can be 0.001% by mass or more, etc. The water absorption rate (% by mass) can be measured by the method described in the examples below.

[0021] From the viewpoint of significantly obtaining the effects of the present invention, the water absorption rate (% by volume) of the cured product of the resin composition layer is preferably 0.45% by volume or less, preferably 0.4% by volume or less, more preferably 0.35% by volume or less. The lower limit is not particularly limited, and it can be 0.001% by volume or more, etc. The water absorption rate (% by volume) can be measured by the method described in the examples below.

[0022] The resin composition layer may further contain optional components in combination with components (A) to (C). Examples of the optional components include (D) elastomer, (E) radically polymerizable compound, (F) curing agent, (G) curing accelerator, (H) other additives, and the like. Hereinafter, each component contained in the resin composition layer will be described in detail.

[0023] In the present invention, the content of each component in the resin composition layer is a value when the non-volatile components in the resin composition layer are 100% by mass, unless otherwise specified. The non-volatile components mean the entire non-volatile components excluding the solvent in the resin composition layer.

[0024] <(A) Epoxy resin> The resin composition layer contains, as component (A), an (A) epoxy resin. By including the (A) epoxy resin in the resin composition layer, a cured product with excellent adhesion can be obtained. The (A) epoxy resin may be used alone or in combination of two or more.

[0025] Examples of the (A) epoxy resin include novolac epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, glycidyl cyclohexane type epoxy resin, alkyldiglycidyl ether type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, phenolphthalimide type epoxy resin, and the like. The epoxy resin may be used alone or in combination of two or more.

[0026] The resin composition layer preferably contains, as component (A), an epoxy resin having two or more epoxy groups in one molecule. From the viewpoint of significantly obtaining the desired effects of the present invention, the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more with respect to 100% by mass of the (A) epoxy resin.

[0027] Epoxy resins include liquid epoxy resins (hereinafter sometimes referred to as "liquid epoxy resins") that are liquid at a temperature of 20°C and solid epoxy resins (hereinafter sometimes referred to as "solid epoxy resins") that are solid at a temperature of 20°C. The resin composition layer may contain only a liquid epoxy resin as the component (A), only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin.

[0028] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0029] Examples of the liquid epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, glycidyl amine type epoxy resin, epoxy resin having a butadiene structure, glycidyl cyclohexane type epoxy resin, phenol phthalimide type epoxy resin, and alkyldiglycidyl ether type epoxy resin. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, and alkyldiglycidyl ether type epoxy resin are more preferred, and bisphenol A type epoxy resin and bisphenol F type epoxy resin are even more preferred.

[0030] Specific examples of the liquid epoxy resin include "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "jER828EL", "825", "Epicoat 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YED216D" (alkyl diglycidyl ether-type epoxy resin) manufactured by Mitsubishi Chemical Corporation, etc. These may be used alone or in combination of two or more.

[0031] As the solid epoxy resin, a solid epoxy resin having two or more epoxy groups in one molecule is preferable, a solid epoxy resin having three or more epoxy groups in one molecule is more preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

[0032] As the solid epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, tris-phenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, and tetraphenylethane type epoxy resin are preferred, and biphenyl type epoxy resin is more preferred.

[0033] Specific examples of the solid epoxy resin include "HP4032H" (naphthalene-type epoxy resin), "HP-4700", "HP-4710" (tetrafunctional naphthalene-type epoxy resin), "N-690" (cresol novolak-type epoxy resin), "N-695" (cresol novolak-type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene-type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin), "NC7000L" (naphthol novolak-type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthalene-type epoxy resin), "ESN485" (naphthol novolak-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YL6121" (biphenyl-type epoxy resin), "YX4000HK" (bixylenol-type epoxy resin), "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100", "CG-500" manufactured by Osaka Gas Chemical Co., Ltd., "YL7760" (bisphenol AF-type epoxy resin), "YL7800" (fluorene-type epoxy resin), "jER1010" (solid bisphenol A-type epoxy resin), "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "WHR-991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., etc. These may be used alone or in combination of two or more.

[0034] When a liquid epoxy resin and a solid epoxy resin are used in combination as component (A), their quantitative ratio (liquid epoxy resin: solid epoxy resin) is preferably 1:0.1 to 1:20, more preferably 1:0.15 to 1:10, and particularly preferably 1:0.2 to 1:5 in terms of mass ratio. When the quantitative ratio of the liquid epoxy resin and the solid epoxy resin is within such a range, the desired effects of the present invention can be remarkably obtained.

[0035] The epoxy equivalent of component (A) is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., still more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. Falling within this range can provide a cured product with a sufficient crosslink density in the cured product of the resin composition layer. The epoxy equivalent is the mass of an epoxy resin containing 1 equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

[0036] From the viewpoint of remarkably obtaining the desired effects of the present invention, the weight average molecular weight (Mw) of component (A) is preferably 100 to 5000, more preferably 150 to 3000, and still more preferably 200 to 1500. The weight average molecular weight of the epoxy resin is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) method.

[0037] From the viewpoint of obtaining a cured product exhibiting good mechanical strength and insulation reliability, when the non-volatile components in the resin composition layer are 100% by mass, the content of component (A) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably 1.5% by mass or more. The upper limit of the content of the epoxy resin is preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 5.5% by mass or less from the viewpoint of remarkably obtaining the desired effects of the present invention.

[0038] <(B) A silane coupling agent having an epoxy group and a trialkoxysilyl group and having 2 or more epoxy groups> The resin composition layer contains, as component (B), a silane coupling agent having an epoxy group and a trialkoxysilyl group and having two or more epoxy groups. The silane coupling agent having an epoxy group and a trialkoxysilyl group and having two or more epoxy groups as component (B) does not include those corresponding to component (A) described above. By including component (B) in the resin composition layer, it becomes possible to obtain a cured product having excellent embedability and excellent adhesion before the HAST test. Component (B) may be used alone or in any combination of two or more kinds.

[0039] (B) component can use a silane coupling agent having a trialkoxysilyl group. Examples of the trialkoxysilyl group include a trimethoxysilyl group, a triethoxysilyl group, a tripropoxysilyl group, a tributoxysilyl group, a tripentyloxysilyl group, a trihexyloxysilyl group, etc. From the viewpoint of significantly obtaining the effects of the present invention, a trimethoxysilyl group or a triethoxysilyl group is preferable, and a triethoxysilyl group is more preferable. When component (B) has a plurality of trialkoxysilyl groups, the trialkoxysilyl groups may be the same or different.

[0040] (B) component can use a silane coupling agent having two or more epoxy groups. The number of epoxy groups that can be contained in component (B) is 2 or more, preferably 3 or more, more preferably 4 or more. The upper limit is not particularly limited and can be 100 or less, etc.

[0041] Also, from the viewpoint of significantly obtaining the effects of the present invention, component (B) preferably has a urethane group (-NH-CO-O-).

[0042] (B) component's epoxy group and trialkoxysilyl group are preferably bonded via one or more groups selected from the group consisting of an oxygen atom, an alkylene group, and a urethane group, and the one or more groups preferably contain a urethane group. The alkylene group may be linear, branched, or cyclic, but from the viewpoint of significantly obtaining the effects of the present invention, a linear one is preferred. The alkylene group is preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and even more preferably an alkylene group having 1 to 3 carbon atoms. The alkylene group may have a substituent. Examples of the substituent include a hydroxy group, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an arylalkyl group, a silyl group, an acyl group, an acyloxy group, a carboxy group, a sulfo group, a cyano group, a nitro group, a mercapto group, an oxo group, etc., and a hydroxy group is preferred.

[0043] (B) component's terminal is preferably a trialkoxysilyl group or a hydroxy group.

[0044] (B) component preferably has a structure represented by the following formula (B-1).

Chemical formula

[0045] R 1 , R 2 , and R 3The alkyl group having 1 to 6 carbon atoms represented by may be linear, branched, or cyclic. The alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, preferably an alkyl group having 1 or 2 carbon atoms, and particularly preferably an alkyl group having 2 carbon atoms. Examples of such alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, etc. A methyl group and an ethyl group are preferable, and an ethyl group is more preferable.

[0046] As the component (B), in addition to the structure represented by the formula (B-1), it preferably has one or more selected from the group consisting of the structure represented by the following formula (B-2) and the structure represented by the following formula (B-3). In the formula (B-2) and the formula (B-3), * represents a bond.

Chemical formula

[0047] As the component (B), commercially available products may be used. Examples of commercially available products include "X-12-981S", "X-12-984S", etc. manufactured by Shin-Etsu Chemical Co., Ltd.

[0048] From the viewpoint of significantly obtaining the effects of the present invention, the weight average molecular weight of the component (B) is preferably 3000 or less, more preferably 2500 or less, and further preferably 2000 or less. The lower limit is not particularly limited, but it can be 100 or more, etc.

[0049] The form of the component (B) contained in the resin composition layer of the present invention is not particularly limited, but it is preferably contained in the resin composition layer in any of the following forms (i) to (iii), more preferably contained in the resin composition layer in either of the forms (i) and (iii), and further preferably contained in the resin composition layer in the form (ii). (i) Contained in the resin composition layer alone as the component (B). (ii) The component (B) is contained as a surface treatment agent for the (C) inorganic filler. (iii)(B) component is contained as a surface treatment agent for (C) inorganic filler and is contained in the resin composition layer alone as (B) component.

[0050] "The fact that (B) component is contained as a surface treatment agent for (C) inorganic filler" means that (C) inorganic filler is surface-treated with (B) component. In this case, (B) component usually exists on the surface of (C) inorganic filler. Also, "being contained in the resin composition layer alone as (B) component" means that (B) component is not contained as a surface treatment agent for (C) inorganic filler. In the case where (B) component is not contained as a surface treatment agent for (C) inorganic filler, (B) component is free in the resin composition layer.

[0051] When (B) component is contained alone in the resin composition layer, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition layer are 100% by mass, the content of (B) component is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and preferably 3% by mass or less, more preferably 1.5% by mass or less, still more preferably 1% by mass or less.

[0052] When (B) component is contained as a surface treatment agent for (C) component, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition layer are 100% by mass, the content of (B) component is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1.5% by mass or less.

[0053] When (B) component is contained as a surface treatment agent for (C) component, the degree of surface treatment by (B) component (content of (B) component) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, or 0.6% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, based on 100% by mass of (C) inorganic filler, from the viewpoint of significantly obtaining the effects of the present invention.

[0054] <(C) Inorganic filler> The resin composition layer contains (C) inorganic filler as the (C) component. The (C) inorganic filler has a thermal conductivity of 20 W / m·K or more. By including the (C) inorganic filler in the resin composition layer, it becomes possible to obtain a cured product with high thermal conductivity.

[0055] The material of the (C) component is not particularly limited as long as its thermal conductivity is within the above range. Examples of the material contained in the (C) component include alumina, aluminum nitride, boron nitride, silicon carbide, etc. Among these, alumina is particularly preferred. The (C) component may be used alone or in combination of two or more. Also, two or more of the same material may be used in combination.

[0056] From the viewpoint of obtaining a cured product excellent in both thermal conductivity and embedability, the average particle size of the (C) component is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and preferably 0.1 μm or more, more preferably 1.0 μm or more, still more preferably 1.5 μm or more. The average particle size of the (C) component can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a particle size distribution of the inorganic filler on a volume basis with a laser diffraction scattering type particle size distribution measuring device and taking the median diameter as the average particle size. As the measurement sample, a dispersion of the (C) component in water by ultrasonic waves can preferably be used. As the laser diffraction scattering type particle size distribution measuring device, "LA-500" manufactured by Horiba, Ltd., "SALD2200" manufactured by Shimadzu Corporation, etc. can be used.

[0057] From the viewpoint of obtaining a cured product excellent in both thermal conductivity and embedability, the specific surface area of the (C) component is preferably 0.5 m 2 / g or more. The specific surface area of the (B) component is preferably 0.5 m 2 / g to 10 m 2 / g, and preferably 0.5 m 2 / g to 5 m 2 / g is more preferable. The specific surface area of the component (B) can be measured by the nitrogen BET method. Specifically, it can be measured using an automatic specific surface area measuring device, and as the automatic specific surface area measuring device, "Macsorb HM-1210" manufactured by Mountech Co., Ltd. etc. can be used.

[0058] (C) component may be surface-treated with a silane coupling agent other than the (B) component from the viewpoint of enhancing moisture resistance and dispersibility. Examples of the silane coupling agent other than the (B) component include amino-silane-based coupling agents, epoxy-silane-based coupling agents, mercapto-silane-based coupling agents, silane-based coupling agents, alkoxysilane compounds, organosilazane compounds, titanate-based coupling agents, etc. Examples of commercially available products of the surface treatment agent other than the (B) component include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM5783" (N-phenyl-3-aminooctyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., etc. The (C) component may be surface-treated with two or more kinds of surface treatment agents.

[0059] From the viewpoint of improving the dispersibility of the (C) inorganic filler, it is preferable that the degree of surface treatment with the surface treatment agent falls within a predetermined range. Specifically, it is preferable that 100% by mass of the (C) inorganic filler is surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably surface-treated with 0.2% to 3% by mass, and even more preferably surface-treated with 0.3% to 2% by mass.

[0060] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the (C) inorganic filler. The amount of carbon per unit surface area of the (C) inorganic filler is preferably 0.02 mg / m 2 or more from the viewpoint of improving the dispersibility of the (C) inorganic filler, more preferably 0.1 mg / m 2 or more, and even more preferably 0.2 mg / m 2 or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer and the melt viscosity in the sheet form, 1.0 mg / m 2 or less is preferable, 0.8 mg / m 2 or less is more preferable, and 0.5 mg / m 2 or less is even more preferable.

[0061] The amount of carbon per unit surface area of the (C) inorganic filler can be measured after washing the surface-treated inorganic filler with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler surface-treated with the surface treatment agent, and ultrasonic cleaning is performed at 25 °C for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used.

[0062] The content (% by mass) of the (C) component is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, or 82% by mass or more when the non-volatile components in the resin composition layer are 100% by mass from the viewpoint of obtaining an insulating layer excellent in both thermal conductivity and embeddability. The upper limit is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less.

[0063] The content of component (C) (volume %) is preferably 50% by volume or more, more preferably 55% by volume or more, still more preferably 60% by volume or more, when the non-volatile components in the resin composition layer are taken as 100% by volume, from the viewpoint of obtaining an insulating layer excellent in both thermal conductivity and embedability. The upper limit is preferably 80% by volume or less, more preferably 75% by volume or less, still more preferably 70% by volume or less. The content of component (C) (volume %) can be measured using the specific gravity of each component described in the column of "<Measurement of water absorption rate (volume %)> " in the examples described later.

[0064] <(D) Elastomer> In addition to the above-described components, the resin composition layer may further contain (D) elastomer as an optional component. The (D) elastomer as this (D) component does not include those corresponding to the above-described components (A) to (B). The (D) component may be used alone or in combination of two or more.

[0065] As the (D) component, it is preferably a resin having at least one structure selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in the molecule, more preferably a resin having one or more structures selected from a polybutadiene structure, a poly(meth)acrylate structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, or a polycarbonate structure, still more preferably a resin having one or more structures selected from a polybutadiene structure and a polyalkyleneoxy structure, and particularly preferably a resin having a polybutadiene structure. Note that "(meth)acrylate" is a term encompassing methacrylate, acrylate, and combinations thereof. These structures may be contained in the main chain or in the side chain.

[0066] (D) component preferably has a high molecular weight in order to reduce the warpage when the resin composition layer is cured. The number average molecular weight (Mn) of component (D) is preferably 1,000 or more, more preferably 1,500 or more, still more preferably 3,000 or more, and 5,000 or more. The upper limit is preferably 1,000,000 or less, more preferably 900,000 or less. The number average molecular weight (Mn) is the number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

[0067] (D) component preferably has a functional group capable of reacting with the (A) epoxy resin from the viewpoint of significantly obtaining the effects of the present invention. Note that the functional group capable of reacting with the (A) epoxy resin includes functional groups that appear by heating.

[0068] In a preferred embodiment, the functional group capable of reacting with the (A) epoxy resin is one or more functional groups selected from the group consisting of a hydroxy group, a carboxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group. Among them, as the functional group, a hydroxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group are preferred, a hydroxy group, an acid anhydride group, a phenolic hydroxyl group, and an epoxy group are more preferred, and a phenolic hydroxyl group is particularly preferred. However, when the functional group contains an epoxy group, the number average molecular weight (Mn) is preferably 5,000 or more.

[0069] A preferred embodiment of component (D) is a resin containing a polybutadiene structure, and the polybutadiene structure may be contained in the main chain or the side chain. Note that the polybutadiene structure may be partially or entirely hydrogenated. A resin containing a polybutadiene structure is referred to as a polybutadiene resin.

[0070] Specific examples of the polybutadiene resin include "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", "Ricon 184MA6" (acid anhydride group-containing polybutadiene) manufactured by Cray Valley; "GQ-1000" (polybutadiene with hydroxyl group and carboxyl group introduced), "G-1000", "G-2000", "G-3000" (polybutadiene with hydroxyl groups at both ends), "GI-1000", "GI-2000", "GI-3000" (hydrogenated polybutadiene with hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) manufactured by Nagase ChemteX Corporation, etc. As one embodiment, linear polyimide (polyimide described in JP-A-2006-37083 and WO 2008 / 153208) using hydroxyl group-terminated polybutadiene, diisocyanate compound and tetrabasic acid anhydride as raw materials, phenol hydroxyl group-containing butadiene, etc. may be mentioned. The content rate of the butadiene structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. The details of the polyimide resin can be referred to the descriptions in JP-A-2006-37083 and WO 2008 / 153208, and this content is incorporated herein.

[0071] (D) A preferred embodiment of the component is a resin containing a poly(meth)acrylate structure. A resin containing a poly(meth)acrylate structure is referred to as a poly(meth)acrylic resin. Examples of the poly(meth)acrylic resin include Taisan Resin manufactured by Nagase ChemteX Corporation, "ME-2000", "W-116.3", "W-197C", "KG-25", "KG-3000", etc. manufactured by Negami Kogyo Co., Ltd.

[0072] (D) component's preferred embodiment is a resin containing a polycarbonate structure. A resin containing a polycarbonate structure is called a polycarbonate resin. Examples of polycarbonate resins include "T6002" and "T6001" (polycarbonate diol) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd. Also, a linear polyimide using a hydroxyl group-terminated polycarbonate, a diisocyanate compound, and a tetracarboxylic dianhydride as raw materials can be used. The content rate of the carbonate structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. Details of the polyimide resin can be referred to the description in International Publication No. 2016 / 129541, and this content is incorporated herein.

[0073] Also, as another embodiment of the (D) component, it is a resin containing a siloxane structure. A resin containing a siloxane structure is called a siloxane resin. Examples of siloxane resins include "SMP-2006", "SMP-2003PGMEA", "SMP-5005PGMEA" manufactured by Shin-Etsu Silicone Co., Ltd., a linear polyimide using an amine group-terminated polysiloxane and a tetracarboxylic dianhydride as raw materials (International Publication No. 2010 / 053185, Japanese Patent Application Laid-Open No. 2002-12667, Japanese Patent Application Laid-Open No. 2000-319386, etc.).

[0074] (D) component's another embodiment is a resin containing an alkylene structure and an alkyleneoxy structure. A resin containing an alkylene structure is called an alkylene resin, and a resin containing an alkyleneoxy structure is called an alkyleneoxy resin. The polyalkyleneoxy structure preferably has 2 to 15 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 5 to 6 carbon atoms. Specific examples of alkylene resins and alkyleneoxy resins include "PTXG-1000" and "PTXG-1800" manufactured by Asahi Kasei Fibers Corporation.

[0075] (D) component's other embodiments include resins containing an isoprene structure. Resins containing an isoprene structure are called isoprene resins. Specific examples of isoprene resins include "KL-610", "KL613", etc. manufactured by Kuraray Co., Ltd.

[0076] (D) component's other embodiments include resins containing an isobutylene structure. Resins containing an isobutylene structure are called isobutylene resins. Specific examples of isobutylene resins include "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer), "SIBSTAR-042D" (styrene-isobutylene diblock copolymer), etc. manufactured by Kaneka Corporation.

[0077] (D) The content of the elastomer, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition layer are 100% by mass, is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more. The upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.

[0078] <(E) Radical polymerizable compound> In addition to the above-described components, the resin composition layer may further contain (E) a radical polymerizable compound as an optional component. The (E) radical polymerizable resin as this (E) component does not include those corresponding to the above-described (A) to (D) components. The (E) radical polymerizable compound may be used alone or in any combination of two or more.

[0079] (E) The radically polymerizable compound is, in one embodiment, a radically polymerizable compound having an ethylenically unsaturated bond. The (E) radically polymerizable compound is not particularly limited, and examples thereof include unsaturated hydrocarbon groups such as allyl group, 3-cyclohexenyl group, 3-cyclopentenyl group, p-vinylphenyl group, m-vinylphenyl group, o-vinylphenyl group; α,β-unsaturated carbonyl groups such as acryloyl group, methacryloyl group, maleimide group (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl group), etc., and may have a radically polymerizable group. The (E) radically polymerizable compound preferably has two or more radically polymerizable groups.

[0080] Examples of the (E) radically polymerizable compound may include maleimide-based radically polymerizable compounds, (meth)acrylic-based radically polymerizable compounds, styrene-based radically polymerizable compounds, allyl-based radically polymerizable compounds, and the like. Among them, from the viewpoint of significantly obtaining the effects of the present invention, maleimide-based radically polymerizable compounds are preferred.

[0081] The maleimide-based radically polymerizable compound is, for example, a compound having one or more, preferably two or more maleimide groups. The maleimide-based radically polymerizable compound may be an aliphatic maleimide compound containing an aliphatic amine skeleton or an aromatic maleimide compound containing an aromatic amine skeleton. Examples of commercially available products include "SLK-2600" manufactured by Shin-Etsu Chemical Co., Ltd., "BMI-1500", "BMI-1700", "BMI-3000J", "BMI-689", "BMI-2500" (maleimide compound containing a dimer diamine structure) manufactured by Designer Molecules, Inc., "BMI-6100" (aromatic maleimide compound) manufactured by Designer Molecules, Inc., "MIR-5000-60T", "MIR-3000-70MT" (biphenyl aralkyl type maleimide compound) manufactured by Nippon Kayaku Co., Ltd., "BMI-70", "BMI-80" manufactured by K.I. Kasei Co., Ltd., "BMI-2300", "BMI-TMH" manufactured by Daiwa Kasei Kogyo Co., Ltd., and the like. Further, as the maleimide-based radically polymerizable compound, a maleimide resin (maleimide compound containing an indane ring skeleton) disclosed in the Invention Association Publication Technical Report Publication No. 2020-500211 may be used.

[0082] (Meth)acrylic radical polymerizable compounds are, for example, compounds having one or more, preferably two or more acryloyl groups and / or methacryloyl groups. Examples of (meth)acrylic radical polymerizable compounds include low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylate compounds such as cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tetra(meth)acrylate; low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylate compounds such as dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylate compounds such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate; high molecular weight (molecular weight 1000 or more) acrylate compounds such as (meth)acryl-modified polyphenylene ether resin, and the like.Examples of commercially available (meth)acrylic radical polymerizable compounds include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate), "DCP" (tricyclodecane dimethanol dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate), "KAYARAD R-604" (dioxane glycol diacrylate) of Nippon Kayaku Co., Ltd., "SA9000", "SA9000-111" (methacryl-modified polyphenylene ether) manufactured by SABIC Innovative Plastics, etc.

[0083] Styrene-based radical polymerizable compounds are, for example, compounds having one or more, preferably two or more vinyl groups directly bonded to aromatic carbon atoms. Examples of styrene-based radical polymerizable compounds include low molecular weight (molecular weight less than 1000) styrene-based compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, bis(4-vinylphenyl) ether; high molecular weight (molecular weight 1000 or more) styrene-based compounds such as vinylbenzyl-modified polyphenylene ether resin, styrene-divinylbenzene copolymer, etc. Examples of commercially available styrene-based radical polymerizable compounds include, for example, "ODV-XET(X03)", "ODV-XET(X04)", "ODV-XET(X05)" (styrene-divinylbenzene copolymer) manufactured by Nippon Steel Chemical & Material Co., Ltd., "OPE-2St 1200", "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resin) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0084] An allyl radical polymerizable compound is, for example, a compound having one or more, preferably two or more allyl groups. Examples of the allyl radical polymerizable compound include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, diallyl 2,3-naphthalenedicarboxylate; allyl ester compounds of isocyanuric acid such as 1,3,5-triallyl isocyanurate, 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; allyl silane compounds such as diallyl diphenyl silane and the like. Commercially available products of the allyl radical polymerizable compound include "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kayaku Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nittetsu Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Wako Pure Chemical Industries, Ltd., the product name "DAND" (diallyl 2,3-naphthalenedicarboxylate) manufactured by Nippon Distillation Industry Co., Ltd., "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Kasei Kogyo Co., Ltd., "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Kasei Co., Ltd. and the like.

[0085] (E) The ethylene unsaturated bond equivalent of the radical polymerizable compound is preferably 20 g / eq. to 3000 g / eq., more preferably 50 g / eq. to 2500 g / eq., still more preferably 70 g / eq. to 2000 g / eq., and particularly preferably 90 g / eq. to 1500 g / eq. The ethylene unsaturated bond equivalent is the mass of the radical polymerizable compound per equivalent of the ethylene unsaturated bond.

[0086] (E) The weight average molecular weight (Mw) of the radically polymerizable compound is preferably 40,000 or less, more preferably 10,000 or less, still more preferably 5,000 or less, and particularly preferably 3,000 or less from the viewpoint of reducing the melt viscosity of the resin composition layer and improving the embeddability. The lower limit is not particularly limited, but can be, for example, 150 or more.

[0087] (E) From the viewpoint of significantly obtaining the desired effects of the present invention, when the non-volatile components in the resin composition layer are 100% by mass, the content of the (E) component is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less.

[0088] <(F) Curing agent> In addition to the above-described components, the resin composition layer may further contain an (F) curing agent as an optional component. Compounds corresponding to the (A) to (E) components are excluded from the (F) curing agent. As the (F) curing agent, a compound having a function of reacting with the (A) component to cure the resin composition layer can be used. Examples thereof include active ester-based curing agents, phenol-based curing agents, naphthol-based curing agents, carbodiimide-based curing agents, benzoxazine-based curing agents, and cyanate ester-based curing agents. Among them, from the viewpoint of improving insulation reliability, the (F) curing agent preferably contains any one or more of active ester-based curing agents, phenol-based curing agents, and naphthol-based curing agents, more preferably contains any one or more of active ester-based curing agents and phenol-based curing agents, and still more preferably contains a phenol-based curing agent. The (F) curing agent may be used alone or in combination of two or more.

[0089] As the phenolic curing agent and the naphtholic curing agent, from the viewpoints of heat resistance and water resistance, a phenolic curing agent having a novolak structure or a naphtholic curing agent having a novolak structure is preferable. Further, from the viewpoint of adhesion to the conductor layer, a nitrogen-containing phenolic curing agent is preferable, and a phenolic curing agent containing a triazine skeleton is more preferable.

[0090] Specific examples of the phenolic curing agent and the naphtholic curing agent include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN-495V", "SN375", "SN395" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA3018-50P", "EXB-9500", "KA-1163" manufactured by DIC Corporation, and the like.

[0091] The active ester-based curing agent is not particularly limited, but generally, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc., are preferably used. The active ester-based curing agent is preferably obtained by a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. Particularly from the viewpoint of improving heat resistance, an active ester-based curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester-based curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc. Examples of the phenol compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0092] Specifically, an active ester compound containing a dicyclopentadiene-type diphenol structure, an active ester compound containing a naphthalene structure, an active ester compound containing an acetylated product of phenol novolak, and an active ester compound containing a benzoylated product of phenol novolak are preferred. Among them, an active ester compound containing a naphthalene structure and an active ester compound containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" represents a divalent structural unit composed of phenylene-dicyclopentylene-phenylene.

[0093] Commercially available products of active ester-based curing agents include, as active ester compounds containing a dicyclopentadiene-type diphenol structure, "EXB-9451", "EXB-9460", "EXB-9460S", "HPC-8000-65T", "HPC-8000H-65TM", "HPC-8000L-65TM" (manufactured by DIC Corporation); as active ester compounds containing a naphthalene structure, "EXB-9416-70BK", "EXB-8100L-65T", "EXB-8150-65T", "EXB-8150L-65T", "HPC-8150-60T", "HPC-8150-62T", "HP-B-8151-62T" (manufactured by DIC Corporation); as an active ester compound containing an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester compound containing a benzoylated product of phenol novolak, "YLH1026" (manufactured by Mitsubishi Chemical Corporation); as an active ester-based curing agent that is an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester-based curing agent that is a benzoylated product of phenol novolak, "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and as an active ester compound containing a styryl group, "PC1300-02-65MA" (manufactured by Air Water Inc.), etc.

[0094] The carbodiimide curing agent is a compound having one or more carbodiimide groups (-N=C=N-) in one molecule, and the carbodiimide curing agent is preferably a compound having two or more carbodiimide groups in one molecule.

[0095] Specific examples of the carbodiimide-based curing agent include commercially available carbodiimide-based curing agents such as Carbodilite V-03 (carbodiimide group equivalent: 216, V-05 (carbodiimide group equivalent: 262), V-07 (carbodiimide group equivalent: 200), V-09 (carbodiimide group equivalent: 200), and Stavaxol P (carbodiimide group equivalent: 302), all manufactured by Nisshinbo Chemical Co., Ltd.

[0096] Specific examples of benzoxazine-based curing agents include "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0097] Examples of the cyanate ester curing agent include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolak and cresol novolak; prepolymers in which part of these cyanate resins is triazine-ized, and the like. Specific examples of the cyanate ester curing agent include "PT30" and "PT60" (phenol novolak type polyfunctional cyanate ester resin), "ULL-950S" (polyfunctional cyanate ester resin), "BA230", "BA230S75" (prepolymer in which part or all of bisphenol A dicyanate is triazine-ized to form a trimer), etc. manufactured by Lonza Japan Co., Ltd.

[0098] (A) component and (F) component, the ratio of their amounts is preferably in the range of 1:0.01 to 1:10, more preferably 1:0.3 to 1:5, and even more preferably 1:0.4 to 1:4, in the ratio of [total number of epoxy groups in (A) component]:[total number of active groups in (F) component]. Here, the "total number of epoxy groups in the epoxy resin" is the total value obtained by summing up the values obtained by dividing the mass of the non-volatile component of the (A) component present in the resin composition layer by the epoxy equivalent. Also, the "total number of active groups in the (F) component" is the total value obtained by summing up the values obtained by dividing the mass of the non-volatile component of the (F) component present in the resin composition layer by the active group equivalent. By setting the ratio of the amounts of the (F) component and the (A) component within such a range, the effects of the present invention can be remarkably obtained.

[0099] (F) The content of the component is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, when the non-volatile components in the resin composition layer are taken as 100% by mass, from the viewpoint of significantly obtaining the desired effects of the present invention. The upper limit is preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less.

[0100] <(G) Curing accelerator> In addition to the components described above, the resin composition layer may further contain (G) a curing accelerator as an optional component. The (G) curing accelerator as this (G) component does not include those corresponding to the above-described components (A) to (F). The (G) component usually functions as a catalyst in the reaction between the (A) epoxy resin and the (F) component to accelerate the curing of the resin composition layer.

[0101] Examples of the (G) component include imidazole-based curing accelerators, amine-based curing accelerators, guanidine-based curing accelerators, phosphorus-based curing accelerators, metal-based curing accelerators, etc. Among them, imidazole-based curing accelerators are preferred as the (G) component. The (G) component may be used alone or in combination of two or more.

[0102] Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline and adducts of imidazole compounds and epoxy resins. 2-Ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred.

[0103] As the imidazole-based curing accelerator, commercially available products may be used. Examples thereof include "1B2PZ" manufactured by Shikoku Kasei Kogyo Co., Ltd. and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0104] Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Among them, 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene are preferred.

[0105] As the amine-based curing accelerator, commercially available products may be used. For example, "DMAP" manufactured by Tokyo Chemical Industry Co., Ltd. can be mentioned.

[0106] Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide, etc. Among them, dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0107] Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc. Among them, triphenylphosphine and tetrabutylphosphonium decanoate are preferred.

[0108] Examples of the metal-based hardening accelerator include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of the organometallic complex include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salt include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0109] (G) From the viewpoint of significantly obtaining the desired effects of the present invention, when the non-volatile components in the resin composition layer are 100% by mass, the content of the component (G) is preferably 0.01% by mass or more, more preferably 0.015% by mass or more, still more preferably 0.02% by mass or more, and preferably 0.3% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less.

[0110] <(H) Other Additives> In addition to the components described above, the resin composition layer may further contain (H) other additives as optional components. Examples of such additives include inorganic fillers (excluding those corresponding to component (C)); thermoplastic resins (excluding those corresponding to component (D)); polymerization initiators; organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as benton and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic-based flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photopolymerization initiation aids such as tertiary amines; photosensitizers such as pyralizones, anthracenes, coumarins, xanthones, and thioxanthones. (H) Other additives may be used alone or in combination of two or more.

[0111] The resin composition layer may contain a solvent as a volatile component. Examples of the solvent include ketones such as methyl ethyl ketone (MEK) and cyclohexanone; aromatic hydrocarbons such as xylene and tetramethylbenzene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate; aliphatic hydrocarbons such as octane and decane; and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These can be used alone or in combination of two or more.

[0112] The amount of the solvent is preferably small from the viewpoint of adjusting the melt viscosity of the resin composition layer. When the mass of the entire resin composition layer is 100% by mass, the amount of the solvent (residual solvent amount) in the resin composition layer is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, even more preferably 2.5% by mass or less, and particularly preferably 1.5% by mass or less. The lower limit is not particularly limited and can be, for example, 0.0001% by mass or more.

[0113] From the viewpoints of thinning the printed wiring board and providing a cured product with excellent insulation even if the cured product of the resin composition layer is a thin film, the thickness of the resin composition layer is preferably 100 μm or less, more preferably 75 μm or less, and still more preferably 50 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited and can usually be 5 μm or more, 10 μm or more, etc.

[0114] <Other Layers> In one embodiment, the resin sheet may further include other layers as needed. Such other layers include, for example, a protective film provided on the surface of the resin composition layer that is not joined to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to suppress the adhesion of dust and the like and scratches on the surface of the resin composition layer.

[0115] <Method for manufacturing resin sheet> The resin sheet can be manufactured, for example, by preparing a resin varnish in which the components contained in the resin composition layer are dissolved in a solvent, applying this resin varnish onto a support using a die coater or the like, and further drying it to form a resin composition layer. As the solvent, those described above can be used.

[0116] Drying may be carried out by known methods such as heating and hot air blowing. The drying conditions are not particularly limited, but drying is carried out so that the content of the organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it also varies depending on the boiling point of the solvent in the resin varnish, for example, when using a resin varnish containing 30% by mass to 60% by mass of the solvent, a resin composition layer can be formed by drying at 50°C to 150°C for 1 minute to 10 minutes.

[0117] The resin sheet can be wound up and stored in a roll shape. When the resin sheet has a protective film, it can be used by peeling off the protective film.

[0118] <Physical properties and uses of resin sheet> Since the resin composition layer contains a combination of component (A), component (B), and component (C), it is possible to obtain a cured product with excellent embedability, high thermal conductivity, and high adhesion before and after the HAST test. In addition, the resin sheet usually has a low melt viscosity and excellent storage stability, so it is also possible to obtain a cured product with a low melt viscosity even after being stored in a refrigerator for two weeks and excellent embedability even after being stored in a refrigerator for two weeks.

[0119] The cured product obtained by curing the resin composition layer at 120°C for 30 minutes and then at 200°C for 90 minutes exhibits the property of excellent embedability. Therefore, it provides an insulating layer with excellent embedability. For example, the resin composition layer of the resin sheet is laminated on an inner layer circuit board on which a wiring pattern of 1 mm square lattice is formed. After lamination, the resin composition layer is thermally cured under the conditions of 120°C for 30 minutes and then 200°C for 90 minutes to obtain an insulating layer. When the support of the resin sheet is peeled off and the surface of the insulating layer is observed with a micro-optical microscope, the wiring patterns of all the inner layer circuit boards are embedded in the insulating layer. The evaluation of embedability can be carried out by the method described in the examples below.

[0120] The cured product obtained by thermally curing the resin composition layer at 200°C for 90 minutes exhibits the property of excellent thermal conductivity. Therefore, it provides an insulating layer with excellent thermal conductivity. The thermal conductivity is preferably 1 W / m·K or more, more preferably 1.2 W / m·K or more, still more preferably 1.3 W / m·K or more. The upper limit is not particularly limited, and it can be 10 W / m·K or less, etc. The evaluation of thermal conductivity can be measured by the method described in the examples below.

[0121] The cured product obtained by curing the resin composition layer at 120°C for 30 minutes and then at 200°C for 90 minutes exhibits the property of excellent adhesion (peel strength) to the copper foil before the HAST test. Therefore, it provides an insulating layer with excellent adhesion to the copper foil such as wiring. The peel strength is preferably 0.7 kgf / cm or more, more preferably 0.8 kgf / cm or more, still more preferably 1 kgf / cm or more. The upper limit is not particularly limited, and it can be 10 kgf / cm or less, etc. The adhesion before the HAST test can be measured by the method described in the examples below.

[0122] The cured product obtained by curing the resin composition layer at 120°C for 30 minutes and then at 200°C for 90 minutes exhibits the property of excellent adhesion (peel strength) to copper foil such as wiring after the HAST test. Therefore, it provides an insulating layer with excellent adhesion to copper foil after the HAST test. The peel strength is preferably 0.5 kgf / cm or more, more preferably 0.6 kgf / cm or more, still more preferably 0.7 kgf / cm or more. The upper limit is not particularly limited, and can be 10 kgf / cm or less, etc. The adhesion after the HAST test can be measured by the method described in the examples below.

[0123] Generally, the adhesion of the cured product of the resin composition layer after the HAST test tends to decrease compared to the adhesion before the HAST test. However, the cured product obtained by curing the resin composition layer in the resin sheet of the present invention at 120°C for 30 minutes and then at 200°C for 90 minutes exhibits the property that the decrease in adhesion after the HAST test is suppressed compared to the adhesion before the HAST test. Therefore, it provides an insulating layer in which the decrease in adhesion after the HAST test is suppressed compared to the adhesion before the HAST test. The decrease in adhesion can be evaluated using the retention rate that indicates how much the adhesion decreases compared to the adhesion before the HAST test. A higher retention rate means that the decrease in adhesion after the HAST test is more suppressed. The retention rate is preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, or 95% or more, particularly preferably 100%. The upper limit is not particularly limited, and can be 100% or less, 99% or less, etc. The retention rate of the peel strength after the HAST test can be evaluated by the method described in the examples below.

[0124] The resin composition layer usually exhibits the property of having a low melt viscosity. Therefore, it provides an insulating layer with excellent embedability. The melt viscosity of the resin composition layer is preferably 800 poise or less, more preferably 700 poise or less, still more preferably 600 poise or less. The lower limit is not particularly limited, and can be 100 poise or more, etc. The measurement of the melt viscosity can be carried out by the method described in the examples below.

[0125] Since the resin composition layer generally has excellent storage stability, the resin composition layer in the resin sheet stored in a refrigerator (5°C) for two weeks exhibits the characteristic of having a low melt viscosity. Thus, it provides an insulating layer with excellent embedability. The melt viscosity of the resin composition layer is preferably 900 poise or less, more preferably 850 poise or less, and even more preferably 800 poise or less. The lower limit is not particularly limited and can be, for example, 100 poise or more. The melt viscosity of the resin composition layer stored in a refrigerator for two weeks can be measured by the method described in the examples below.

[0126] Generally, the melt viscosity of the resin composition layer in the resin sheet after being stored in a refrigerator for two weeks tends to increase compared to the melt viscosity of the resin composition layer in the resin sheet before being stored in a refrigerator for two weeks. However, since the resin composition layer in the resin sheet of the present invention generally has excellent storage stability, the ratio (the rate of increase in melt viscosity) of the melt viscosity of the resin composition layer in the resin sheet after being stored in a refrigerator for two weeks to the melt viscosity of the resin composition layer in the resin sheet before being stored in a refrigerator for two weeks is low. The rate of increase is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.2 or less. The lower limit is not particularly limited and can be, for example, 0.01 or more. The rate of increase in melt viscosity can be evaluated by the method described in the examples below.

[0127] Since the resin composition layer generally has excellent storage stability, a cured product obtained by curing the resin composition layer in a resin sheet stored refrigerated (5°C) for two weeks at 120°C for 30 minutes and then at 200°C for 90 minutes exhibits excellent embedability. Therefore, it provides an insulating layer with excellent embedability. For example, the resin composition layer of a resin sheet stored refrigerated for two weeks is laminated on an inner layer circuit board on which a wiring pattern of 1 mm square lattice is formed. After lamination, the resin composition layer is thermally cured under the conditions of 120°C for 30 minutes and then 200°C for 90 minutes to obtain an insulating layer. When the support of the resin sheet is peeled off and the surface of the insulating layer is observed with a micro-optical microscope, there are some insufficient parts in the embedding of the wiring pattern of the inner layer circuit board by the insulating layer. Preferably, all the wiring patterns of the inner layer circuit board are embedded by the insulating layer. The evaluation of embedability can be carried out by the method described in the examples below.

[0128] The resin sheet of the present invention can provide an insulating layer with excellent embedability, high thermal conductivity, and high adhesion before and after the HAST test. Therefore, the resin sheet of the present invention can be suitably used as a resin sheet for forming an insulating layer of a semiconductor chip package (resin sheet for forming an insulating layer of a semiconductor chip package), a resin sheet for forming an insulating layer of a circuit board (including a printed wiring board) (resin sheet for forming an insulating layer of a circuit board), and can be more suitably used as a resin sheet for forming an interlayer insulating layer on which a conductor layer is formed by plating (resin sheet for forming an interlayer insulating layer of a circuit board on which a conductor layer is formed by plating, that is, a resin sheet for forming an interlayer insulating layer of a circuit board formed by a semi-additive process method).

[0129] It can also be suitably used as a resin sheet for sealing a semiconductor chip (resin sheet for forming a semiconductor chip sealing layer) and a resin sheet for forming wiring on a semiconductor chip (resin sheet for forming semiconductor chip wiring).

[0130] [Circuit board] The circuit board of the present invention includes an insulating layer formed by a cured product of the resin composition layer of the resin sheet of the present invention. The manufacturing method of the circuit board of the present invention is as follows: (1) A step of preparing a base material with a wiring layer having a base material and a wiring layer provided on at least one surface of the base material; (2) A step of laminating the resin sheet of the present invention on the base material with a wiring layer so that the wiring layer is embedded in the resin composition layer, and thermally curing to form an insulating layer; (3) including a step of interlayer connecting the wiring layers. Further, the manufacturing method of the circuit board may include (4) a step of removing the base material.

[0131] Step (3) is not particularly limited as long as the wiring layers can be interlayer connected, but it is preferably at least one of the steps of forming via holes in the insulating layer, forming the wiring layers, and polishing or grinding the insulating layer to expose the wiring layers.

[0132] <Step (1)> Step (1) is a step of preparing a base material with a wiring layer having a base material and a wiring layer provided on at least one surface of the base material. Usually, the base material with a wiring layer has, on both surfaces of the base material, a first metal layer and a second metal layer which are parts of the base material in this order, and a wiring layer is formed on the surface of the second metal layer opposite to the surface on the base material side. Specifically, a dry film (photosensitive resist film) is laminated on the base material, exposed and developed under predetermined conditions using a photomask to form a patterned dry film. After forming the wiring layer by electrolytic plating using the developed patterned dry film as a plating mask, the patterned dry film is peeled off. Note that the first metal layer and the second metal layer may not be provided.

[0133] Examples of the base material include substrates such as glass epoxy substrates, metal substrates (such as stainless steel and cold-rolled steel sheets (SPCC)), polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates, and a metal layer such as a copper foil may be formed on the substrate surface. Further, metal layers such as a first metal layer and a second metal layer (for example, an extremely thin copper foil with a carrier copper foil of Mitsui Metal, trade name "Micro Thin") that can be peeled off may be formed on the surface.

[0134] The dry film is not particularly limited as long as it is a photosensitive dry film composed of a photoresist composition. For example, dry films such as novolak resins and acrylic resins can be used. Commercially available products can also be used as the dry film.

[0135] The lamination conditions of the base material and the dry film are the same as those when laminating the resin sheet in step (2) described later so that it is embedded in the wiring layer, and the preferable ranges are also the same.

[0136] After laminating the dry film on the base material, exposure and development are performed under predetermined conditions using a photomask to form a desired pattern on the dry film.

[0137] The line (circuit width) / space (width between circuits) ratio of the wiring layer is not particularly limited, but is preferably 20 / 20 μm or less (i.e., the pitch is 40 μm or less), more preferably 10 / 10 μm or less, still more preferably 5 / 5 μm or less, even more preferably 1 / 1 μm or less, and particularly preferably 0.5 / 0.5 μm or more. The pitch does not have to be the same throughout the entire wiring layer. The minimum pitch of the wiring layer may be 40 μm or less, 36 μm or less, or 30 μm or less.

[0138] After forming the pattern of the dry film, the wiring layer is formed and the dry film is peeled off. Here, the formation of the wiring layer can be carried out by a plating method using the dry film with the desired pattern formed as a plating mask.

[0139] The wiring layer may include not only linear wirings but also, for example, electrode pads (lands) on which external terminals can be mounted. The wiring layer may also be composed only of electrode pads.

[0140] The conductor material used for the wiring layer is not particularly limited. In a preferred embodiment, the wiring layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The wiring layer may be a single-metal layer or an alloy layer. Examples of the alloy layer include those formed from alloys of two or more metals selected from the above group (for example, nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among them, from the viewpoints of general applicability, cost, ease of patterning, etc. for forming the wiring layer, a single-metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy is preferred, a single-metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy is more preferred, and a single-metal layer of copper is even more preferred.

[0141] From the viewpoint of effectively utilizing the effect of excellent embedability, in one example, the wiring layer is preferably thick. The specific range of the thickness of the wiring layer depends on the design of the desired wiring board, but is preferably 3 μm to 35 μm, more preferably 5 μm to 30 μm, still more preferably 10 to 20 μm, or 15 to 20 μm. When adopting the step of polishing or grinding the insulating layer in step (3) to expose the wiring layer for interlayer connection of the wiring layer, it is preferable that the thickness of the wiring for interlayer connection is different from that of the wiring that is not connected. The thickness of the wiring layer can be adjusted by repeating the above-mentioned pattern formation. Among each wiring layer, the thickness of the thickest wiring layer (conductive pillar) depends on the design of the desired wiring board, but is preferably 2 μm or more and 100 μm or less. Also, the wiring for interlayer connection may be convex.

[0142] After forming the wiring layer, the dry film is peeled off. The peeling of the dry film can be carried out, for example, using an alkaline peeling solution such as a sodium hydroxide solution. If necessary, unnecessary wiring patterns can also be removed by etching or the like to form a desired wiring pattern. The pitch of the wiring layer to be formed is as described above.

[0143] <Step (2)> Step (2) is a step of laminating the resin sheet of the present invention on a base material with a wiring layer so that the wiring layer is embedded in the resin composition layer and thermally curing it to form an insulating layer. Specifically, the wiring layer of the base material with a wiring layer obtained in the aforementioned step (1) is laminated so as to be embedded in the resin composition layer of the resin sheet, and the resin composition layer of the resin sheet is thermally cured to form an insulating layer.

[0144] The lamination of the wiring layer and the resin sheet can be carried out, for example, by heat-pressure bonding the resin sheet to the wiring layer from the support side after removing the protective film of the resin sheet. Examples of the member for heat-pressure bonding the resin sheet to the wiring layer (hereinafter also referred to as "heat-pressure bonding member") include a heated metal plate (such as a SUS mirror plate) or a metal roll (such as a SUS roll). It should be noted that it is preferable to press through an elastic material such as heat-resistant rubber so that the resin sheet sufficiently follows the surface unevenness of the wiring layer rather than directly pressing the heat-pressure bonding member against the resin sheet.

[0145] The lamination of the wiring layer and the resin sheet may be carried out by a vacuum lamination method after removing the protective film of the resin sheet. In the vacuum lamination method, the heat-pressure bonding temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the heat-pressure bonding pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa, and the heat-pressure bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions with a pressure of 13 hPa or less.

[0146] After lamination, under normal pressure (atmospheric pressure), for example, a smoothing process of the laminated resin sheet may be performed by pressing a heat-bonding member from the support side. The pressing conditions for the smoothing process can be the same as those for the heat-bonding during the above lamination. Note that lamination and the smoothing process may be continuously performed using the above-mentioned commercially available vacuum laminator.

[0147] After laminating the resin composition layer on the substrate with a wiring layer so that the wiring layer is embedded, the resin composition layer is thermally cured to form an insulating layer. For example, the thermal curing conditions of the resin composition layer vary depending on the type of the resin composition and the like, but the curing temperature can be in the range of 120°C to 240°C, and the curing time can be in the range of 5 minutes to 120 minutes. Before thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature.

[0148] The support of the resin sheet may be peeled off after laminating and thermally curing the resin sheet on the substrate with a wiring layer, or the support may be peeled off before laminating the resin sheet on the substrate with a wiring layer. Also, the support may be peeled off before the roughening process described later.

[0149] After thermally curing the resin composition layer to form an insulating layer, the surface of the insulating layer may be polished. The polishing method is not particularly limited, and it may be polished by a known method. For example, the surface of the insulating layer can be polished using a surface grinding machine.

[0150] <Process (3)> Process (3) is a process for interlayer connection of the wiring layer. Specifically, it is a process of forming a via hole in the insulating layer, forming a conductor layer, and interlayer connecting the wiring layer. Or it is a process of polishing or grinding the insulating layer to expose the wiring layer and interlayer connecting the wiring layer. The conductor layer may be referred to as the wiring layer.

[0151] When adopting the steps of forming via holes in the insulating layer, forming a conductor layer, and performing interlayer connection of wiring layers, the formation of via holes is not particularly limited, and examples include laser irradiation, etching, mechanical drilling, etc., but it is preferably performed by laser irradiation. This laser irradiation can be carried out using any suitable laser processing machine that uses a carbon dioxide laser, YAG laser, excimer laser, etc. as a light source. Specifically, laser irradiation is performed from the surface side of the support of the resin sheet to form via holes that penetrate the support and the insulating layer to expose the wiring layer.

[0152] The conditions of laser irradiation are not particularly limited, and laser irradiation can be carried out by any suitable process according to the selected means and following a conventional method.

[0153] The shape of the via hole, that is, the shape of the opening contour when viewed in the extending direction, is not particularly limited, but generally it is circular (substantially circular).

[0154] After forming the via holes, a so-called desmear process, which is a process for removing smears in the via holes, may be performed. When the conductor layer described later is formed by an electroplating process, for example, a wet desmear treatment may be performed on the via holes. When the conductor layer is formed by a sputtering process, for example, a dry desmear process such as a plasma treatment process may be performed. Also, the desmear process may also serve as a roughening treatment process.

[0155] Before forming the conductor layer, a roughening treatment may be performed on the via holes and the insulating layer. Known procedures and conditions that are usually performed can be adopted for the roughening treatment. Examples of dry roughening treatment include plasma treatment, etc. Examples of wet roughening treatment include a swelling treatment with a swelling solution, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing solution performed in this order.

[0156] The arithmetic mean roughness (Ra) of the surface of the insulating layer after the roughening treatment is preferably 350 nm or more, more preferably 400 nm or more, and even more preferably 450 nm or more. The upper limit is preferably 700 nm or less, more preferably 650 nm or less, and even more preferably 600 nm or less. The arithmetic mean roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0157] After forming the via holes, a conductor layer is formed. The conductor material constituting the conductor layer is not particularly limited, and the conductor layer can be formed by any suitable method known in the art such as plating, sputtering, evaporation, etc., and is preferably formed by plating. A preferred embodiment can form, for example, a conductor layer having a desired wiring pattern by plating on the surface of the insulating layer by a conventionally known technique such as a semi-additive method or a full-additive method. Among these, the semi-additive method is preferred. Also, when the support in the resin sheet is a metal foil, a conductor layer having a desired wiring pattern can be formed by a conventionally known technique such as a subtractive method. The conductor layer may have a single-layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated.

[0158] When forming by plating, specifically, a plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer to expose a part of the plating seed layer corresponding to the desired wiring pattern. An electrolytic plating layer is formed on the exposed plating seed layer by electrolytic plating. At this time, together with the formation of the electrolytic plating layer, the via holes may be filled by electrolytic plating to form field vias. After forming the electrolytic plating layer, the mask pattern is removed. Thereafter, the unnecessary plating seed layer is removed by etching or the like to form a conductor layer having a desired wiring pattern. Note that the dry film used for forming the mask pattern when forming the conductor layer is the same as the above dry film.

[0159] The conductor layer may include not only linear wirings but also, for example, electrode pads (lands) on which external terminals can be mounted. Further, the conductor layer may be composed only of electrode pads.

[0160] Further, the conductor layer may be formed by forming an electrolytic plating layer and a via hole without using a mask pattern after forming a seed layer, and then performing patterning by etching.

[0161] When adopting a process of polishing or grinding an insulating layer to expose a wiring layer and making an interlayer connection of the wiring layer, the polishing method or grinding method of the insulating layer is not particularly limited as long as the wiring layer can be exposed and the polished or ground surface is horizontal, and a conventionally known polishing method or grinding method can be applied. For example, a chemical mechanical polishing method using a chemical mechanical polishing apparatus, a mechanical polishing method using a buff or the like, a surface grinding method by rotating a grinding wheel, etc. may be mentioned. Similar to the process of forming a via hole in the insulating layer, forming a conductor layer, and making an interlayer connection of the wiring layer, a smear removal process and a process of performing roughening treatment may be performed, and a conductor layer may be formed. Further, it is not necessary to expose all the wiring layers, and a part of the wiring layer may be exposed.

[0162] <Step (4)> Step (4) is a step of removing a base material and forming the circuit board of the present invention. The method of removing the base material is not particularly limited. A preferred embodiment is to peel the base material from the circuit board at the interface between the first and second metal layers, and etch and remove the second metal layer with, for example, an aqueous copper chloride solution. If necessary, the base material may be peeled off with the conductor layer protected by a protective film.

[0163] [Semiconductor Chip Package] A first aspect of the semiconductor chip package of the present invention is a semiconductor chip package in which a semiconductor chip is mounted on the above circuit board. The semiconductor chip package can be manufactured by bonding a semiconductor chip to the above circuit board.

[0164] As long as the terminal electrode of the semiconductor chip is in conductive connection with the circuit wiring of the circuit board, the bonding conditions are not particularly limited, and known conditions used in flip-chip mounting of the semiconductor chip may be used. Further, the semiconductor chip and the circuit board may be bonded via an insulating adhesive.

[0165] In a preferred embodiment, the semiconductor chip is pressure-bonded to the circuit board. As the pressure-bonding conditions, for example, the pressure-bonding temperature may be in the range of 120°C to 240°C (preferably in the range of 130°C to 200°C, more preferably in the range of 140°C to 180°C), and the pressure-bonding time may be in the range of 1 second to 60 seconds (preferably 5 seconds to 30 seconds).

[0166] In another preferred embodiment, the semiconductor chip is reflowed and bonded to the circuit board. As the reflow conditions, for example, it can be in the range of 120°C to 300°C.

[0167] After bonding the semiconductor chip to the circuit board, for example, it is also possible to obtain a semiconductor chip package by filling the semiconductor chip with a mold underfill material. The method of filling with the mold underfill material can be carried out by a known method.

[0168] In the second aspect of the semiconductor chip package of the present invention, the semiconductor chip package of the present invention can be manufactured, for example, by a method including the following steps (A) to (F) using the resin sheet of the present invention. In order to form the sealing layer in step (C) or the rewiring formation layer in step (E), the resin composition layer of the resin sheet of the present invention may be used. Hereinafter, an example of forming a sealing layer and a rewiring formation layer using the resin sheet of the present invention is shown. However, the technology for forming the sealing layer and the rewiring formation layer of the semiconductor chip package is known, and those skilled in the art can manufacture a semiconductor chip package according to known technology using the resin sheet of the present invention. (A) A step of laminating a temporary fixing film on a base material, (B) A step of temporarily fixing a semiconductor chip on the temporary fixing film, (C) A step of forming a sealing layer on the semiconductor chip, (D) Step of peeling the base material and the temporary fixing film from the semiconductor chip (E) Step of forming a redistribution formation layer as an insulating layer on the surface from which the base material and the temporary fixing film of the semiconductor chip have been peeled, and (F) Step of forming a redistribution layer as a conductor layer on the redistribution formation layer

[0169] <Step (A)> In step (A), a temporary fixing film is laminated on the base material. The material used for the base material is not particularly limited. Examples of the base material include a silicon wafer; a glass wafer; a glass substrate; a metal substrate such as copper, titanium, stainless steel, cold-rolled steel sheet (SPCC); a substrate in which glass fibers are impregnated with an epoxy resin or the like and heat-cured (for example, an FR-4 substrate); a substrate made of a bismaleimide triazine resin (BT resin), and the like.

[0170] The temporary fixing film is not particularly limited in material as long as it can be peeled from the semiconductor chip in step (D) and can temporarily fix the semiconductor chip. A commercially available product can be used as the temporary fixing film. Examples of commercially available products include Rivar Alpha manufactured by Nitto Denko Corporation.

[0171] <Step (B)> In step (B), the semiconductor chip is temporarily fixed on the temporary fixing film such that its electrode pad surface is joined to the temporary fixing film. The temporary fixing of the semiconductor chip can be performed using a known apparatus such as a flip chip bonder or a die bonder. The layout and the number of arrangements of the semiconductor chips can be appropriately set according to the shape and size of the temporary fixing film, the production number of the target semiconductor package, etc. For example, they can be aligned and temporarily fixed in a matrix shape with multiple rows and multiple columns.

[0172] <Step (C)> The resin sheet of the present invention is laminated on the semiconductor chip and cured (for example, thermally cured) to form a sealing layer.

[0173] The lamination of the semiconductor chip and the resin sheet can be carried out by heat - pressure bonding the resin sheet to the semiconductor chip from the support side after removing the protective film of the resin sheet if necessary. The lamination of the semiconductor chip and the resin sheet may be carried out by a vacuum lamination method, and the lamination conditions are the same as those in step (2) of the manufacturing method of the circuit board.

[0174] After lamination, the resin composition layer is thermally cured to form a sealing layer. The thermal curing conditions are the same as those in step (2) of the manufacturing method of the circuit board.

[0175] The support of the resin sheet may be peeled off after laminating and thermally curing the resin sheet on the semiconductor chip, or the support may be peeled off before laminating the resin sheet on the semiconductor chip.

[0176] <Process (D)> The method of peeling the base material and the temporary fixing film can be appropriately changed according to the material of the temporary fixing film, etc. For example, methods such as heating and foaming (or expanding) the temporary fixing film to peel it, and irradiating ultraviolet rays from the base material side to reduce the adhesive force of the temporary fixing film and peel it can be mentioned.

[0177] In the method of heating and foaming (or expanding) the temporary fixing film to peel it, the heating conditions are usually 100 - 250 °C for 1 - 90 seconds or 5 - 15 minutes. Also, in the method of irradiating ultraviolet rays from the base material side to reduce the adhesive force of the temporary fixing film and peel it, the irradiation amount of ultraviolet rays is usually 10 mJ / cm 2 ~1000 mJ / cm 2 is.

[0178] <Process (E)> The material for forming the redistribution formation layer (insulating layer) is not particularly limited as long as it has insulating properties when forming the redistribution formation layer (insulating layer). From the viewpoint of ease of manufacturing the semiconductor chip package, photosensitive resin and thermosetting resin are preferable. The redistribution formation layer may be formed using the resin sheet of the present invention.

[0179] After forming the rewiring formation layer, via holes may be formed in the rewiring formation layer in order to make an interlayer connection between the semiconductor chip and a conductor layer described later. The via holes may be formed by a known method according to the material of the rewiring formation layer.

[0180] <Process (F)> The material of the conductor layer formed on the rewiring formation layer is not particularly limited. In a preferred embodiment, the conductor layer is the same as the conductor material used for the wiring layer in the circuit board. The conductor material is as described above. The conductor layer may have a single-layer structure or a multilayer structure in which two or more single-metal layers or alloy layers made of different kinds of metals or alloys are laminated.

[0181] The thickness of the conductor layer depends on the design of the desired semiconductor chip package, but is generally 1 μm to 35 μm, preferably 1 μm to 20 μm.

[0182] In one embodiment, the conductor layer may be formed by plating. For example, by a conventionally known technique such as a semi-additive method or a full-additive method, plating is performed on the surface of the rewiring formation layer to form a conductor layer having a desired wiring pattern. From the viewpoint of manufacturing simplicity, it is preferable to form it by the semi-additive method. Hereinafter, an example of forming the conductor layer by the semi-additive method will be shown.

[0183] First, a plating seed layer is formed on the surface of the rewiring formation layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer to expose a part of the plating seed layer corresponding to the desired wiring pattern. After forming a metal layer by electroplating on the exposed plating seed layer, the mask pattern is removed. Then, an unnecessary plating seed layer is removed by etching or the like to form a conductor layer (rewiring layer) having a desired wiring pattern.

[0184] Note that processes (E) and (F) may be repeated to alternately stack (build up) the conductor layer (rewiring layer) and the rewiring formation layer (insulating layer).

[0185] In manufacturing a semiconductor chip package, the steps of (G) forming a solder resist layer on a conductor layer (redistribution layer), (H) forming bumps, and (I) dicing and singulating a plurality of semiconductor chip packages into individual semiconductor chip packages may be further performed. These steps may be carried out according to various methods known to those skilled in the art and used in the manufacture of semiconductor chip packages.

[0186] The above-described second embodiment is an example of a manufacturing method in which a semiconductor chip is first provided and a redistribution layer is formed on the electrode pad surface thereof, that is, the Chip-1 method. The semiconductor chip package of the present invention may be manufactured by the Chip-1 method or, in addition to such a Chip-1 method, a method in which a redistribution layer is first provided, and a semiconductor chip is provided and sealed in a state where the electrode pad surface thereof can be electrically connected to the redistribution layer, that is, the RDL-1 method. st ) method. st ) method.

[0187] [Semiconductor device] Examples of semiconductor devices in which the semiconductor chip package of the present invention is to be mounted include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical devices, and televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, and airplanes, etc.).

[0188] [Electronic component] The electronic member of the present invention has an electronic component, a cured product of the resin composition layer of the resin sheet of the present invention provided on the electronic component, and a heat dissipation member mounted on the cured product. Since the cured product of the resin composition layer has a high thermal conductivity, for example, by providing the cured product of the resin composition layer on the electronic component so as to adhere the cured product to the electronic component and mounting the heat dissipation member on the cured product, the heat dissipation efficiency from the electronic component to the heat dissipation member is increased. The method for forming the cured product can be carried out by the same method as the above-mentioned step (2). The electronic member of the present invention may have a plurality of heat dissipation members. In this case, the electronic member preferably has an electronic component, a first cured product of the resin composition layer of the resin sheet of the present invention provided on the electronic component, a first heat dissipation member mounted on the first cured product, a second cured product of the resin composition layer of the resin sheet of the present invention provided on the heat dissipation member, and a second heat dissipation member mounted on the second cured product. The first cured product and the second cured product may be the same component or different components. Also, the first heat dissipation member and the second heat dissipation member may be the same heat dissipation member or different heat dissipation members.

[0189] Examples of the heat dissipation member include a heat spreader, a heat sink, etc. Examples of the electronic component include a semiconductor chip package, a power semiconductor, an LED-PKG, etc. Examples of the electronic member include a circuit board, a semiconductor chip package, a semiconductor device, etc.

Examples

[0190] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass%", respectively, unless otherwise specified. Also, the operations described below were carried out in an environment of normal temperature and normal pressure unless otherwise specified.

[0191] The inorganic fillers 1 to 9 used in the examples and comparative examples are as follows. · Inorganic filler 1: Alumina particles with an average particle size of 1.5 μm, surface-treated with 1% by mass of X-12-981S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 2: Alumina particles with an average particle size of 1.5 μm, surface-treated with 1.5% by mass of X-12-981S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 3: Alumina particles with an average particle size of 1.5 μm, surface-treated with 0.5% by mass of X-12-981S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 4: Alumina particles with an average particle size of 1.5 μm, surface-treated with 1% by mass of X-12-984S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 5: Alumina particles with an average particle size of 1.5 μm, surface-treated with 0.5% by mass of X-12-984S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 6: Alumina particles with an average particle size of 1.5 μm, surface-treated with 0.5% by mass of KBM573 (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 7: Alumina particles with an average particle size of 1.5 μm, surface-treated with 0.5% by mass of KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100% by mass of the inorganic filler · Inorganic filler 8: Alumina particles with an average particle size of 1.5 μm, not surface-treated with a surface treatment agent · Inorganic filler 9: Silica particles with an average particle size of 1.5 μm, surface-treated with 1% by mass of X-12-981S (manufactured by Shin-Etsu Chemical Co., Ltd.) based on 100 parts by mass of the inorganic filler (thermal conductivity is 1 W / m·K)

[0192] X-12-981S is a silane coupling agent that contains the structure represented by the following formula (1) and the structure represented by the following formula (2), and the terminal group is a hydroxyl group or a group represented by the following formula (3). The epoxy equivalent with respect to one structure represented by formula (1) is 3, the epoxy equivalent is 290 g / mol, the average number of epoxy groups in one molecule is 3.0, and the weight average molecular weight is 870.

[0193] X-12-984S is a silane coupling agent that contains the structure represented by the following formula (1) and the structure represented by the following formula (2), and has a hydroxyl group or a group represented by the following formula (3) as a terminal group. The epoxy equivalent with respect to one structure represented by formula (1) is 3, the epoxy equivalent is 270 g / mol, the average number of epoxy groups in one molecule is 5.7, and the weight average molecular weight is 1540.

Chemical formula

[0194] KBM573 used in the inorganic filler 6 has the following structure.

Chemical formula

[0195] KBM403 used in the inorganic filler 7 has the following structure.

Chemical formula

[0196] <Synthesis Example 1: Synthesis of Elastomer 1> In a reaction vessel, 50 g of bifunctional hydroxyl group-terminated polybutadiene (number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1800 g / eq., solid content 100 mass%: "G-3000" manufactured by Nippon Soda Co., Ltd.), 23.5 g of an aromatic hydrocarbon-based mixed solvent ("Ipzol 150" manufactured by Idemitsu Petrochemical Co., Ltd.), and 0.005 g of dibutyltin laurate were mixed and uniformly dissolved. When it became uniform, the temperature was raised to 50 °C, and while further stirring, 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) was added, and the reaction was carried out for about 3 hours. Next, after cooling this reaction product to room temperature, 8.96 g of benzophenone tetracarboxylic dianhydride (acid anhydride equivalent = 161.1 g / eq.), 0.07 g of triethylenediamine, and 40.4 g of ethyl diglycol acetate (manufactured by Daicel Corporation) were added thereto, and the temperature was raised to 130 °C while stirring, and the reaction was carried out for about 4 hours. By FT-IR at 2250 cm -1The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was regarded as the end point of the reaction. After cooling the reaction product to room temperature, it was filtered through a 100-mesh filter cloth to obtain Elastomer 1 having an imide structure, a urethane structure, and a polybutadiene structure (non-volatile component: 50% by mass). The number average molecular weight was 13,700.

[0197] <Synthesis Example 2: Synthesis of Elastomer 2> In a reaction vessel, 69 g of bifunctional hydroxyl-terminated polybutadiene (number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1800 g / eq., solid content 100% by mass, "G-3000" manufactured by Nippon Soda Co., Ltd.), 40 g of an aromatic hydrocarbon-based mixed solvent ("Ipzol 150" manufactured by Idemitsu Petrochemical Co., Ltd.), and 0.005 g of dibutyltin laurate were mixed and uniformly dissolved. When it became uniform, the temperature was raised to 50°C, and while further stirring, 8 g of isophorone diisocyanate (manufactured by Evonik Degussa Japan Co., Ltd., IPDI, isocyanate group equivalent = 113 g / eq) was added, and the reaction was carried out for about 3 hours. Next, after cooling this reaction product to room temperature, 23 g of cresol novolak resin ("KA-1160" manufactured by DIC Corporation, hydroxyl group equivalent = 117 g / eq.) and 60 g of ethyl diglycol acetate (manufactured by Daicel Corporation) were added thereto, and the temperature was raised to 80°C with stirring, and the reaction was carried out for about 4 hours. The disappearance of the NCO peak at 2250 cm-1 was confirmed by FT-IR. The disappearance of the NCO peak was regarded as the end point of the reaction. After cooling the reaction product to room temperature, it was filtered through a 100-mesh filter cloth to obtain Elastomer 2 having a polybutadiene structure and phenolic hydroxyl groups (non-volatile component: 50% by mass). The number average molecular weight was 5500.

[0198] <Synthesis Example 3: Synthesis of Elastomer 3> A monomer composition obtained by mixing 46.5 g of BPADA, 12.6 g of BPPAN, 38.3 g of PRIAMINE 1075, 1.1 g of maleic anhydride, and 40 g of toluene as a solvent in 400 g of N,N-dimethylacetamide (hereinafter also referred to as "DMAc") as a solvent was stirred and reacted at normal temperature and atmospheric pressure for 3 hours. Thereby, a solution of polyamic acid was obtained. Subsequently, after heating the solution of polyamic acid, while maintaining it at about 160 °C, condensed water was removed azeotropically with toluene under a nitrogen stream. It was confirmed that a predetermined amount of water had accumulated in the water determination receiver and that the outflow of water was no longer visible. After confirmation, the reaction solution was further heated and stirred at 200 °C for 1 hour. Then, it was cooled. Thereby, elastomer 3 (non-volatile component 20 mass%) was obtained. The number average molecular weight was 8800.

[0199] <Example 1> 6 parts of a bisphenol type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "ZX-1059", a 1:1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent 165 g / eq.), 2 parts of a biphenyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., "NC3100", epoxy equivalent 258 g / eq.) were heated and dissolved in 10 parts of MEK with stirring to obtain a resin solution. This resin solution was cooled to room temperature. Then, 20 parts of elastomer 1 (non-volatile component 50 mass%), 10 parts of a maleimide resin (40 mass% toluene solution of "BMI689" manufactured by Designer Molecule), 8 parts of a phenol novolak resin (50 mass% toluene solution of "TD-2090" manufactured by DIC, phenol equivalent 105 g / eq.), 0.5 part of a curing accelerator (10 mass% MEK solution of 1-benzyl-2-phenylimidazole "1B2PZ"), 140 parts of inorganic filler 1, and 18 parts of MEK were mixed with the above resin solution and uniformly dispersed with a high-speed rotary mixer to obtain a mixture. Then, the above mixture was filtered through a cartridge filter ("SHP020" manufactured by ROKITECHNO) to produce a resin varnish.

[0200] On a polyethylene terephthalate (PET) film (Toray Industries, Inc.'s "Lumirror R80", thickness 38 μm, softening point 130 °C) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation), a resin varnish was applied with a die coater so that the thickness of the resin composition layer after drying would be 40 μm, and then dried at 100 °C for 4 minutes to obtain a resin sheet A containing the resin composition layer. Also, a resin sheet B was obtained by storing resin sheet A in a refrigerator (5 °C) for 2 weeks.

[0201] <Example 2> 6 parts of a bisphenol type epoxy resin ("ZX-1059" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., a 1:1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent 165 g / eq.) and 2 parts of a biphenyl type epoxy resin ("NC3100" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 258 g / eq.) were heated and dissolved with stirring in 10 parts of MEK to obtain a resin solution. This resin solution was cooled to room temperature. Then, 20 parts of elastomer 1 (non-volatile component 50% by mass), 10 parts of a maleimide resin (40% by mass toluene solution of "BMI689" manufactured by Designer Molecules, Inc.), 8 parts of a phenol novolak resin ("TD-2090" manufactured by DIC Corporation, 50% by mass toluene solution with a phenol equivalent of 105 g / eq.), 0.5 part of a curing accelerator (10% by mass MEK solution of 1-benzyl-2-phenylimidazole "1B2PZ"), 138.5 parts of an inorganic filler 8, 1.5 parts of a silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s X-12-981S), and 18 parts of MEK were added to the above resin solution and mixed uniformly with a high-speed rotating mixer to obtain a mixture. Then, the above mixture was filtered with a cartridge filter ("SHP020" manufactured by ROKITECHNO Co., Ltd.) to produce a resin varnish.

[0202] On a polyethylene terephthalate film (Toray Industries, Inc.'s "Lumirror R80", thickness 38 μm, softening point 130 °C) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation), a resin varnish was applied with a die coater so that the thickness of the resin composition layer after drying would be 40 μm, and then dried at 100 °C for 4 minutes to obtain a resin sheet A containing the resin composition layer. Also, a resin sheet B was obtained by storing resin sheet A in a refrigerator (5 °C) for 2 weeks.

[0203] <Example 3> In Example 1, the amount of Inorganic filler 1 was changed from 140 parts to 150 parts. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0204] <Example 4> In Example 1, the amount of Inorganic filler 1 was changed from 140 parts to 125 parts. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0205] <Example 5> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 2. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0206] <Example 6> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 3. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0207] <Example 7> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 4. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0208] <Example 8> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 5. Resin varnish, Resin sheet A, and Resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0209] <Example 9> In Example 1, 1) Replace 6 parts of bisphenol type epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "ZX-1059", a 1:1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent 165 g / eq.) with 4 parts of aliphatic epoxy resin (manufactured by Mitsubishi Chemical Corporation, "YED216D", epoxy equivalent 120 g / eq.). 2) Change the amount of biphenyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., "NC3100", epoxy equivalent 258 g / eq.) from 2 parts to 4 parts. Except for the above matters, resin varnish, resin sheet A, and resin sheet B were prepared in the same manner as in Example 1.

[0210] <Example 10> In Example 1, 1) Change the amount of phenol novolac resin (manufactured by DIC Corporation, "TD-2090", a 50% by mass toluene solution with a phenol equivalent of 105 g / eq.) from 8 parts to 4 parts. 2) Use 4 parts of a phenolic curing agent (manufactured by DIC Corporation, "LA-3018-50P", active group equivalent of about 151 g / eq., solid content 50%). Except for the above matters, resin varnish, resin sheet A, and resin sheet B were prepared in the same manner as in Example 1.

[0211] <Example 11> In Example 10, change 4 parts of the phenolic curing agent (manufactured by DIC Corporation, "LA-3018-50P", active group equivalent of about 151 g / eq., solid content 50%) to 3.1 parts of an active ester type curing agent (manufactured by DIC Corporation, "HPC-8000-65T", active ester group equivalent of about 223 g / eq., a toluene solution with a non-volatile component ratio of 65%). Except for the above matters, resin varnish, resin sheet A, and resin sheet B were prepared in the same manner as in Example 10.

[0212] <Example 12> In Example 1, change 20 parts of elastomer 1 (non-volatile component 50% by mass) to 20 parts of elastomer 2 (non-volatile component 50% by mass). Except for the above matters, resin varnish, resin sheet A, and resin sheet B were prepared in the same manner as in Example 1.

[0213] <Example 13> In Example 1, 20 parts of Elastomer 1 (non-volatile component: 50% by mass) were changed to 50 parts of Elastomer 3 (non-volatile component: 20% by mass). A resin varnish, a resin sheet A, and a resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0214] <Example 14> In Example 1, 10 parts of a maleimide resin (40% by mass toluene solution of "BMI689" manufactured by Designer Molecules) were changed to 10 parts of a maleimide resin (40% by mass toluene solution of "BMI-1500" manufactured by Designer Molecules). A resin varnish, a resin sheet A, and a resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0215] <Comparative Example 1> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 6. A resin varnish, a resin sheet A, and a resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0216] <Comparative Example 2> In Example 1, 140 parts of Inorganic filler 1 were changed to 140 parts of Inorganic filler 7. A resin varnish, a resin sheet A, and a resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0217] <Comparative Example 3> In Example 1, 140 parts of Inorganic filler 1 were changed to 100 parts of Inorganic filler 9. A resin varnish, a resin sheet A, and a resin sheet B were produced in the same manner as in Example 1, except for the above matters.

[0218]

Table 1

Table 2

[0219] <Measurement of Melt Viscosity> After peeling off the supports of Resin Sheet A and Resin Sheet B, the resin composition layer was compressed with a mold to produce measurement pellets (diameter 18 mm, 1.0 g to 1.1 g). Then, for these measurement pellets, using a dynamic viscoelasticity measuring device (“Rheosol-G3000” manufactured by UBM Co., Ltd.), the minimum melt viscosity was measured. Specifically, for 1 g of the measurement pellets, using a parallel plate with a diameter of 18 mm, the temperature was raised from an initial temperature of 60°C to 200°C, and the dynamic viscoelastic modulus was measured. The measurement conditions were a heating rate of 5°C / min, a measurement temperature interval of 2.5°C, a frequency of 1 Hz, and a strain of 5 deg.

[0220] Also, the ratio of the melt viscosity of Resin Sheet A to the melt viscosity of Resin Sheet B (melt viscosity of Resin Sheet B / melt viscosity of Resin Sheet A) was calculated to obtain the increase rate of the melt viscosity.

[0221] <Evaluation of Embeddability> As an inner layer circuit board, a glass cloth base epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.3 mm, “R1515F” manufactured by Panasonic Corporation) having circuit conductors (copper) formed with a wiring pattern of 1 mm square grid (copper residue ratio 70%) on both sides was prepared. The resin composition layer of Resin Sheet A prepared in the examples and comparative examples was laminated on the inner layer circuit board. Lamination was performed by reducing the pressure for 30 seconds to make the atmospheric pressure 13 hPa or less, and then pressure-bonding at 100°C and a pressure of 0.74 MPa for 30 seconds. Next, under atmospheric pressure, heat pressing was performed at 100°C and a pressure of 0.5 MPa for 60 seconds to smooth the resin composition layer. After peeling off the support of Resin Sheet A, the resin composition layer was cured under curing conditions of 120°C for 30 minutes and then 200°C for 90 minutes to obtain an insulating layer.

[0222] The support was peeled off, and the surface of the insulating layer was observed with a micro-optical microscope and evaluated according to the following evaluation criteria. 〇: The wiring patterns of all the inner layer circuit boards are embedded in the insulating layer. △: There are some insufficient parts in the embedding of the wiring patterns of the inner layer circuit boards by the insulating layer. ×: The embedding of the wiring patterns of the inner layer circuit boards by the insulating layer is insufficient as a whole.

[0223] Also, the resin sheet B was evaluated for its embedding property in the same manner as the resin sheet A.

[0224] <Measurement of Adhesion (Peel Strength 1) with Copper Foil before HAST Test> The support of the resin sheet A laminated on the roughened copper-clad laminate was peeled off to expose the resin composition layer. The resin composition layer and the ultra-low roughness electrolytic copper foil (「TQ-M4-VSP」manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 18 μm, arithmetic mean roughness (Ra) 110 nm) were laminated so that the laminate surface of the ultra-low roughness electrolytic copper foil was joined to the resin composition layer. The lamination was carried out by reducing the pressure for 30 seconds to make the atmospheric pressure 13 hPa or less, and then crimping at 100 °C and a pressure of 0.74 MPa for 30 seconds. Next, under atmospheric pressure, it was hot-pressed at 100 °C and a pressure of 0.5 MPa for 60 seconds to smooth the resin composition layer. Further, the resin composition layer was cured under the curing conditions of 120 °C for 30 minutes and then 200 °C for 90 minutes to obtain a sample (evaluation substrate A) having a layer structure of 「roughened copper-clad laminate / hardened product of resin composition layer / copper foil」.

[0225] An incision was made in the copper foil of the evaluation substrate A to surround a portion with a width of 10 mm and a length of 100 mm. One end of this portion was peeled off and grasped with a gripping tool (auto-comb type tester 「AC-50C-SL」manufactured by T.S.E. Co., Ltd.), and the load (kgf / cm) when it was peeled off vertically by 20 mm at a speed of 50 mm / min at room temperature was measured to obtain the peel strength (peel strength 1) between the copper foil. Also, the peel strength 1 was evaluated according to the following criteria. 〇: The peel strength is 0.9 kgf / cm or more △: Peel strength is less than 0.9 kgf / cm

[0226] <Measurement of adhesion (peel strength 2) with copper foil after HAST test> The evaluation substrate A was subjected to a HAST test in an environment of a temperature of 130°C and a humidity of 85% RH for 100 hours. After the HAST test, the peel strength between the copper foil and the insulating layer of the evaluation substrate A was measured in the same manner as before the HAST test.

[0227] Also, the ratio of the adhesion (peel strength 1) with the copper foil before the HAST test to the adhesion (peel strength 2) with the copper foil after the HAST test ((peel strength 2 / peel strength 1) × 100) was calculated to obtain the retention rate of the adhesion with the copper foil, and it was evaluated according to the following criteria. 〇: Retention rate is 80% or more △: Retention rate is 70% or more and less than 80% ×: Retention rate is less than 70%

[0228] <Measurement of water absorption rate (mass%)> After heating the resin sheet A at 200°C for 90 minutes to thermoset the resin composition layer, the released PET film was peeled off. The obtained cured product (thickness 40 μm) was cut into test pieces of 4 cm square, and after drying the test pieces at 130°C for 30 minutes, they were weighed (this weighed mass is denoted as X (g)). The test pieces were immersed in boiled ion-exchanged water for 1 hour. Then, the test pieces were immersed in ion-exchanged water at room temperature (25°C) for 1 minute, and the water droplets on the surface of the test pieces were wiped off with a clean wiper (manufactured by Kuraray Flex Co., Ltd.) and weighed (this weighed mass is denoted as Y (g)). The boiling water absorption rates (mass%) of five test pieces were respectively obtained from the following formula, and the average value was shown in the following table. Boiling water absorption rate (mass%) = ((Y - X) / X) × 100

[0229] <Measurement of water absorption rate (volume%)> (A) component, (B) component, (D) component, (E) component, (F) component, and (G) component have a specific gravity of 1.1 g / cm 3 , (C) component has a specific gravity of 3.9 g / cm 3 , (H) component has a specific gravity of 2.2 g / cm3 The volume (cm 3 ) of the resin composition layer was calculated. The boiling water absorption amount (cm 3 ) was calculated from the boiling water absorption rate (mass %), and the boiling water absorption rate (volume %) was calculated by dividing it by the volume (cm 3 ) of the resin composition layer.

[0230] <Measurement of Thermal Conductivity> (1) Preparation of cured sample The resin varnishes prepared in the examples and comparative examples were applied onto a PET film (Toray Industries, Inc.'s "Lumirror R80", thickness 38 μm, softening point 130 °C) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) using a die coater so that the thickness of the resin composition layer after drying would be 100 μm, and dried at 80 °C to 100 °C (average 90 °C) for 7 minutes to obtain a resin composition layer.

[0231] Using a batch type vacuum pressure laminator (Nikko Materials Co., Ltd.'s 2-stage build-up laminator "CVP700"), after stacking three resin composition layers, lamination was performed, and the resin composition layer was cured under curing conditions of 200 °C for 90 minutes to obtain a cured sample. The lamination was performed by reducing the pressure for 30 seconds to make the atmospheric pressure 13 hPa or less, and then pressing at 100 °C and a pressure of 0.4 MPa for 20 seconds.

[0232] (2) Measurement of thermal diffusivity α The thermal diffusivity α (m 2 / s) in the thickness direction of the cured sample was measured by the temperature wave analysis method using "ai-Phase Mobile 1u" manufactured by ai-Phase. The same sample was measured three times, and the average value was calculated.

[0233] (3) Measurement of specific heat capacity Cp Regarding the cured sample, using a differential scanning calorimeter ("DSC7020" manufactured by SII NanoTechnology Inc.), the temperature was raised from -40 °C to 80 °C at 10 °C / min and measured, and thus the specific heat capacity Cp (J / kg·K) of the cured sample at 25 °C was calculated.

[0234] (4) Measurement of density ρ The density (kg / m3) of the cured sample was measured using an analytical balance (METTLER TOLEDO's "XP105" (using a specific gravity measurement kit)).

[0235] (5) Calculation of thermal conductivity λ The thermal diffusivity α (m 2 / s), specific heat capacity Cp (J / kg·K), and density ρ (kg / m 3 ) obtained in the above (2) to (4) were substituted into the following formula (I) to calculate the thermal conductivity λ (W / m·K) of the cured product, and evaluation was performed according to the following criteria. λ = α × Cp × ρ (I) 〇: Thermal conductivity is 1.3 W / m·K or more △: Thermal conductivity is 0.8 W / m·K or more and less than 1.3 W / m·K ×: Thermal conductivity is less than 0.8 W / m·K

[0236]

Table 3

Table 4

[0237] In Examples 1 to 14, even when the components (D) to (G) are not contained, although there are differences to some extent, it has been confirmed that the results are the same as those of the above examples.

Claims

1. A resin sheet comprising a support and a resin composition layer provided on the support, wherein the resin composition layer (A) an epoxy resin, (B) a silane coupling agent having an epoxy group and a trialkoxysilyl group and having 2 or more epoxy groups, and (C) an inorganic filler, and component (C) is alumina, the thermal conductivity of component (C) is 20 W / mK or more, when the content of component (C) is 100% by volume of the non-volatile components in the resin composition layer, it is 50% by volume or more, a resin sheet having a water absorption rate of 0.2% by mass or less for a cured product obtained by heating the resin composition layer at 200°C for 90 minutes.

2. The resin sheet according to claim 1, wherein component (B) is included as a surface treatment agent for component (C).

3. The resin sheet according to claim 1, wherein when the content of component (C) is 100% by mass of the non-volatile components in the resin composition layer, it is 70% by mass or more.

4. The resin sheet according to claim 1, further comprising (D) an elastomer.

5. The resin sheet according to claim 1, wherein component (B) contains a triethoxysilyl group.

6. In the resin sheet before storage in a refrigerator (5°C) for 2 weeks, the resin sheet according to claim 1, wherein the minimum melt viscosity of the resin composition layer is 800 poise or less.

7. In the resin sheet after storage in a refrigerator (5°C) for 2 weeks, the resin sheet according to claim 1, wherein the minimum melt viscosity of the resin composition layer is 900 poise or less.

8. A circuit board including an insulating layer formed of a cured product of the resin composition layer of the resin sheet according to any one of claims 1 to 7.

9. A semiconductor chip package including a cured product of the resin composition layer of the resin sheet according to any one of claims 1 to 7.

10. A semiconductor device including the semiconductor chip package according to claim 9.

11. An electronic component having an electronic component, a cured product of the resin composition layer of the resin sheet according to any one of claims 1 to 7 provided on the electronic component, and a heat dissipation member mounted on the cured product.

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