Resin composition, resin sheet and method for producing the same, circuit board and method for manufacturing the same, and semiconductor device

Abstract

To provide a resin composition which can suppress swelling of a bleed-out part.SOLUTION: A resin composition contains (A) an epoxy resin and (B) a curing agent, wherein (B) the curing agent contains an active ester-based resin, a ratio M(B) / M(A) of the number M (B) of functional groups of (B) the curing agent to the number M (A) of epoxy groups of (A) the epoxy resin is 1.4 or more, when an evaluation test for heating a test layer obtained by heating a resin composition layer formed of the resin composition at 130°C for 30 minutes and at 170°C for 30 minutes, at 175°C for 30 minutes is performed, a mass reduction ratio of the test layer by heating at 175°C for 30 minutes is 3% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a resin sheet and a method for producing the same, a circuit board and a method for producing the same, and a semiconductor device. [Background technology]

[0002] Circuit boards such as printed wiring boards are widely used in various electronic devices. A known method for manufacturing circuit boards is a build-up method in which insulating layers and conductor layers are alternately stacked on an inner layer substrate. The insulating layer is formed, for example, by forming a resin composition layer containing a resin composition and curing the resin composition layer. A known method for forming a resin composition layer on an inner layer substrate is to laminate a resin sheet having a support and a resin composition layer onto the inner layer substrate (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-172221 Summary of the Invention [Problem to be solved by the invention]

[0004] In the process of laminating an inner layer substrate and a resin sheet during the manufacturing process of a circuit board, heat and pressure are applied to the resin composition layer, causing the resin composition layer to become fluid. As a result, a portion of the resin composition layer may seep out from the gap between the inner layer substrate and the support. Hereinafter, the portion of the resin composition layer or insulating layer that seeps out from the gap between the inner layer substrate and the support may be referred to as a "bleed-out portion."

[0005] In order to meet recent high-level requirements, the insulating layer of a circuit board is required to have a low dielectric loss tangent. Therefore, the present inventors attempted to improve the dielectric loss tangent by adopting a resin composition containing an epoxy resin and a curing agent containing an active ester resin in an appropriate quantitative ratio. However, it was found that when using a resin composition containing such a combination of an epoxy resin and a curing agent, blistering occurs in the bleed-out portion of the insulating layer obtained by curing the resin composition layer. Generally, a conductor layer is formed on an insulating layer, and an annealing treatment is performed after the formation of the conductor layer. This annealing treatment can cause blistering in the bleed-out portion of the insulating layer. Such blistering may hinder the smooth execution of subsequent processes (e.g., processes for forming additional insulating layers and conductor layers).

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a resin composition capable of suppressing swelling in the bleed-out portion; a resin sheet capable of suppressing swelling in the bleed-out portion and a method for producing the same; a circuit board including a cured product of the resin composition; a method for producing a circuit board using the resin sheet; and a semiconductor device including the circuit board. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a resin composition containing a specific ratio of an epoxy resin (A) and a curing agent (B) containing an active ester resin (B-1), wherein the rate of mass loss due to heating measured by a specific evaluation test is within a specific range, and have thus completed the present invention. That is, the present invention includes the following.

[0008] <1> A resin composition comprising (A) an epoxy resin and (B) a curing agent; (B) the curing agent comprises an active ester resin; (B) The ratio M(B) / M(A) of the number of active groups of the curing agent M(B) to the number of epoxy groups M(A) of the epoxy resin (A) is 1.4 or more; A resin composition, wherein when a test layer obtained by heating a resin composition layer formed from the resin composition at 130°C for 30 minutes and 170°C for 30 minutes is heated at 175°C for 30 minutes in an evaluation test, the mass loss rate of the test layer due to heating at 175°C for 30 minutes is 3% or less. <2> The evaluation test forming a resin composition layer on a support using the resin composition; laminating the resin composition layer and the inner layer substrate; The resin composition layer is heated at 130°C for 30 minutes and 170°C for 30 minutes, and the support is peeled off to obtain a test layer; and Heating the test layer at 175°C for 30 minutes; in this order, <1> The resin composition according to claim 1. <3> (C) containing an inorganic filler; <1> or <2> The resin composition according to claim 1. <4> (C) The amount of the inorganic filler is 70% by mass or more relative to 100% by mass of the nonvolatile components of the resin composition; <3> The resin composition according to claim 1. <5> The ratio M(B) / M(A) of the number of active groups in the (B) curing agent to the number of epoxy groups in the (A) epoxy resin, M(B) is 1.6 or more. <1> ~ <4> The resin composition according to any one of claims 1 to 10. <6> A resin sheet comprising a support and a resin composition layer formed on the support; The resin composition layer <1> ~ <5> A resin sheet comprising the resin composition according to any one of claims 1 to 4. <7> <6> A method for producing the resin sheet according to the present invention; A step of preparing a resin varnish containing (A) an epoxy resin, (B) a curing agent, and (G) a solvent; A step of applying a resin varnish onto a support; and a step of drying the applied resin varnish to form a resin composition layer; A method for manufacturing a resin sheet, comprising the steps of: <8> Dry the resin varnish at a temperature between 40°C and 150°C for a drying time between 60 seconds and 10 minutes. <7> A method for producing the resin sheet according to claim 1. <9> <1> ~ <5> A circuit board comprising a cured product of the resin composition according to any one of claims 1 to 4. <10> Inner layer board and <6> a step of laminating the resin sheet according to the above item 1 above so that the inner layer substrate and the resin composition layer are bonded to each other; curing the resin composition layer; A method for manufacturing a circuit board, wherein the step of laminating an inner layer substrate and a resin sheet includes allowing a portion of a resin composition layer to seep out from a gap between the inner layer substrate and the support. <11> <9> A semiconductor device comprising the circuit board according to claim 1. [Effects of the Invention]

[0009] According to the present invention, there can be provided a resin composition capable of suppressing swelling in the bleed-out portion; a resin sheet capable of suppressing swelling in the bleed-out portion and a method for producing the same; a circuit board including a cured product of the resin composition; a method for producing a circuit board using the resin sheet; and a semiconductor device including the circuit board. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a method for manufacturing a circuit board according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented within the scope of the claims and their equivalents.

[0012] <Resin composition> (Summary of Resin Composition) A resin composition according to one embodiment of the present invention comprises an epoxy resin (A) and a curing agent (B). The curing agent (B) comprises an active ester resin (B-1). The ratio M(B) / M(A), the number of active groups in the curing agent (B) to the number of epoxy groups in the epoxy resin (A), is in a specific range of 1.4 or more. Furthermore, the resin composition according to this embodiment satisfies the following requirement (R):

[0013] Requirements(R): When an evaluation test is conducted in which a test layer obtained by heating a resin composition layer formed from the resin composition at 130°C for 30 minutes and 170°C for 30 minutes is then heated at 175°C for 30 minutes, the mass loss rate of the test layer due to heating at 175°C for 30 minutes is 3% or less.

[0014] The resin composition according to this embodiment can suppress swelling of the bleed-out portion. Furthermore, the resin composition according to this embodiment can generally provide an insulating layer with a low dielectric tangent. The inventors speculate that the mechanism by which such advantages are obtained is as follows. However, the present invention is not limited to the mechanism described below.

[0015] When manufacturing a circuit board using a resin sheet having a resin composition layer containing a resin composition, the resin sheet and an inner layer substrate are generally laminated, and the resin composition layer is cured to form an insulating layer. The mechanism of curing the resin composition layer involves the reaction of (A) epoxy resin and (B) curing agent contained in the resin composition to form a bond. The reaction between (A) epoxy resin and (B-1) active ester resin contained in (B) curing agent does not produce polar groups such as hydroxyl groups. Therefore, the polarity of the cured product obtained by curing the resin composition can be reduced, and the dielectric loss tangent of the insulating layer can usually be reduced.

[0016] However, some of the (A) epoxy resin may be vaporized by heat. Furthermore, some of the (B-1) active ester resin may also be vaporized by heat. When the (A) epoxy resin and the (B-1) active ester resin are partially vaporized, the amount of resin component in the resin composition decreases. Unless otherwise specified, the "resin component" of a resin composition refers to the non-volatile components contained in the resin composition excluding the (C) inorganic filler. Furthermore, unless otherwise specified, the non-volatile components of a resin composition refer to the components contained in the resin composition excluding the (G) solvent. Because the resin component typically acts as a binder, if the resin component is present in a small amount, the shape of the cured product may not be maintained against the stress generated by the heat of the annealing treatment.

[0017] The majority of the resin composition layer is cured in the gap between the support and the inner layer substrate. In the gap, the resin composition layer is covered by the support and the inner layer substrate. This prevents the resin component from being lost from the resin composition layer due to evaporation. In contrast, the bleed-out portion is the portion that seeps out from the gap between the inner layer substrate and the support. Therefore, at least one side of the bleed-out portion is not covered by the inner layer substrate or the support. Therefore, when the resin composition is subjected to heat during curing, some of the resin component may be vaporized and lost from the bleed-out portion. This reduces the amount of resin component in the bleed-out portion, thereby reducing the ability to maintain the shape of the cured product against the stress generated by the heat of the annealing treatment. It is believed that in the past, the amount of resin component in the bleed-out portion was so small that it resulted in "bulging" in the bleed-out portion.

[0018] Furthermore, the heat of the annealing treatment can cause the volatile component (G) solvent to evaporate and be lost. If the (G) solvent is lost, the (G) solvent may evaporate and expand, causing stress in the cured product. In bleed-out areas where at least one side is not covered by the inner layer substrate or support, the stress cannot be resisted by both the inner layer substrate and the support. Therefore, it is presumed that the stress caused by the expansion of the (G) solvent was also a factor in the "bulging" in the bleed-out area.

[0019] Therefore, in the resin composition according to this embodiment, the resin components and (G) solvent lost when exposed to heat are reduced, thereby suppressing "swelling" in the bleed-out portion. Specifically, the mass loss rate of the test layer in requirement (R) indicates that when the bleed-out portion is exposed to heat equivalent to the heat received during curing of the resin composition, only a small amount of components are lost from the bleed-out portion. Since the (C) inorganic filler is not usually lost due to heat, most or all of the components that may be lost are the resin components or (G) solvent. Therefore, by adopting a composition that minimizes the loss of components to 3% or less, suppression of "swelling" is achieved.

[0020] The evaluation test for the above-mentioned requirement (R) is a test conducted to determine whether or not the requirement (R) is satisfied. Therefore, a resin composition that satisfies the requirement (R) when the above-mentioned evaluation test is conducted is included in the scope of the present invention, regardless of whether or not the evaluation test is conducted.

[0021] (Explanation of Requirement (R)) A resin composition according to one embodiment of the present invention satisfies the above-mentioned requirement (R). That is, when a test layer obtained by heating a resin composition layer formed from the resin composition at 130°C for 30 minutes and 170°C for 30 minutes is subjected to an evaluation test in which the test layer is heated at 175°C for 30 minutes, the mass loss rate of the test layer due to heating at 175°C for 30 minutes is within a specific range of 3% or less. Specifically, the range of the mass loss rate is usually 3% or less, preferably 2.8% or less, and more preferably 2.6% or less. The lower limit is usually 0% or more, and may be 0.5% or more, 1.0% or more, etc.

[0022] Specifically, the evaluation test is carried out as follows. A resin composition layer is formed on a suitable support using the resin composition. When evaluating the resin sheet of the present invention, the support may be the same as the support of the resin sheet. The thickness of the resin composition layer is the same as the thickness of the resin composition layer in the resin sheet. On the other hand, in other cases, a polyethylene terephthalate film may be used as the support. The thickness of the resin composition layer may be 40 μm. The formed resin composition layer contains the resin composition, and usually contains only the resin composition.

[0023] The resin composition layer is then laminated to an inner layer substrate. A polyimide film may be used as the inner layer substrate. The resin composition layer is then heated at 130°C for 30 minutes, and then heated at 170°C for 30 minutes. The support is then peeled off to obtain a test layer on the inner layer substrate. Although heating at 130°C for 30 minutes and 170°C for 30 minutes may cause the resin composition to harden, the hardening usually does not proceed completely. Therefore, the test layer may contain a resin composition in a semi-cured state. In this specification, semi-cured resin compositions are also included in the term "cured product of a resin composition."

[0024] The mass of the test layer thus obtained, W0, is measured. This mass, W0, is sometimes referred to as the "mass of the test layer before heating," W0. The test layer is then heated at 175°C for 30 minutes. Because the support has been peeled off as described above, this heating is performed in an open state, with one side of the test layer uncovered by other components. This open state corresponds to the state of the bleed-out portion uncovered by the support. After heating, the test layer is allowed to cool to room temperature in a desiccator to avoid adsorption of moisture from the air. After cooling, the mass of the test layer, W1, is measured. This mass, W1, is sometimes referred to as the "mass of the test layer after heating," W1. Evaluation tests typically produce a laminate sample comprising an inner layer substrate and a test layer. Therefore, the masses, W0 and W1, of the test layer can be measured by subtracting the mass of the inner layer substrate from the mass of this laminate sample. Generally, the inner layer substrate does not undergo mass change due to the heating, so the mass of the inner layer substrate can be measured before or after.

[0025] Then, the mass loss rate can be calculated by the following formula (M1) using the mass W0 of the test layer before heating and the mass W1 of the test layer after heating. Mass reduction rate (%)=(W0-W1) / W0×100 (M1)

[0026] As a specific procedure for the evaluation test, the method described in the "Test for evaluating mass reduction rate" in the Examples section described later can be adopted.

[0027] One method for obtaining a mass loss rate within a range that satisfies requirement (R) is, for example, to reduce the amount of (G) solvent by thoroughly drying the resin composition during its production process. Generally, a resin composition produced using a (G) solvent may contain the (G) solvent. While most of the (G) solvent is removed by drying during the process of preparing a test layer, some of the (G) solvent may remain in the test layer. Therefore, in order to reduce the amount of (G) solvent contained in the resin composition, it is preferable to thoroughly dry the resin composition during its production process. Since the ease of drying typically varies depending on the type of (G) solvent, it is preferable to set specific drying conditions according to the type of (G) solvent.

[0028] Furthermore, since some of the resin components of the resin composition may be partially vaporized by heat, a method for obtaining a mass loss rate within the range satisfying requirement (R) may include, for example, reducing the amount of such vaporizable components. Specifically, some resins that are liquid at room temperature may be vaporized by heat. Furthermore, some resins that are solid at room temperature may be vaporized by heat, such as the active ester resin (B-1). Therefore, the amount of resin components lost during heating may be reduced by appropriately adjusting the amount of these resins.

[0029] ((A) Explanation of epoxy resin) The resin composition according to this embodiment contains an epoxy resin (A). The epoxy resin (A) is a curable resin having an epoxy group. Examples of (A) epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, phenol aralkyl-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexane dimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, and phenolphthalimidine-type epoxy resins. The (A) epoxy resin may be used alone or in combination of two or more.

[0030] From the viewpoint of obtaining a cured product having excellent heat resistance, the (A) epoxy resin preferably contains an epoxy resin having an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatic rings and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bisxyleneol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexanedimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0031] The (A) epoxy resin preferably contains an epoxy resin having two or more epoxy groups per molecule, and the proportion of the epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the non-volatile components of the (A) epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0032] (A) Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain, as (A) epoxy resin, only liquid epoxy resin, only solid epoxy resin, or a combination of liquid epoxy resin and solid epoxy resin.

[0033] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0034] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, and epoxy resins having a butadiene structure.

[0035] Specific examples of liquid epoxy resins include "HP-4032", "HP-4032-D", and "HP-4032-SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epikote 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol type epoxy resin) manufactured by ADEKA Corporation; and "EP-3950L" and "EP-3980" manufactured by ADEKA Corporation. Examples of epoxy resins include "EP-4088S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation, "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd., "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" manufactured by Daicel Corporation, "JP-100" and "JP-200" (epoxy resins having a butadiene structure) manufactured by Nippon Soda Co., Ltd., and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used alone or in combination of two or more.

[0036] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0037] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins.

[0038] Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); DIC Corporation's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene-type epoxy resins); and DIC Corporation's "EXA-7311." "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4" manufactured by Nippon Steel Chemical & Material Co., Ltd. 100V" (naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "Y" manufactured by Mitsubishi Chemical Corporation Examples include "X7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.These may be used alone or in combination of two or more.

[0039] When a liquid epoxy resin and a solid epoxy resin are used in combination as the (A) epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7. However, since some liquid epoxy resins may volatilize when heated, the specific mass ratio is preferably set depending on the types of liquid epoxy resin and solid epoxy resin so as to satisfy requirement (R).

[0040] The epoxy equivalent of the (A) epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., even more preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0041] The weight average molecular weight (Mw) of the (A) epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0042] The amount of (A) epoxy resin is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the nonvolatile components in the resin composition, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0043] The amount of (A) epoxy resin is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, based on 100% by mass of the resin components in the resin composition.

[0044] The range of the total amount of (A) epoxy resin and (B) curing agent is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on 100% by mass of the resin components in the resin composition. The upper limit is usually 100% by mass or less, and may be 99% by mass or less, 98% by mass or less, etc.

[0045] ((B) Explanation of hardener) The resin composition according to this embodiment contains a (B) curing agent. The (B) curing agent is a resin that can react with and bond with the (A) epoxy resin to cure the resin composition. One type of (B) curing agent may be used alone, or two or more types may be used in combination.

[0046] The (B) curing agent contains an active ester resin (B-1). The active ester resin (B-1) can reduce the polarity of the cured product of the resin composition, thereby effectively reducing the dielectric loss tangent of the insulating layer. Furthermore, some components of some active ester resins (B-1) can be vaporized by heat and lost from the cured product. Therefore, conventional resin compositions containing an active ester resin (B-1) tend to cause swelling in the bleed-out area. In contrast, the resin composition of the present embodiment can suppress swelling in the bleed-out area even when it contains an active ester resin (B-1).

[0047] The (B-1) active ester resin may be a compound having one or more active ester groups per molecule. Among these, preferred (B-1) active ester resins are compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The (B-1) active ester resin is sometimes called an "active ester curing agent" because it reacts with the (A) epoxy resin when combined with the (A) epoxy resin to cure the resin composition. The (B-1) active ester resin may be used alone or in combination of two or more.

[0048] The (B-1) active ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. From the viewpoint of improving heat resistance in particular, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin 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, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, 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, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0049] Specifically, the (B-1) active ester resin is preferably a dicyclopentadiene-type active ester resin, a naphthalene-type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolac, or an active ester resin containing a benzoylated product of phenol novolac, and among these, a naphthalene-type active ester resin is more preferred. The dicyclopentadiene-type active ester resin is preferably an active ester resin containing a dicyclopentadiene-type diphenol structure.

[0050] Commercially available (B-1) active ester resins include, for example, active ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451," "EXB9460," "EXB9460S," "EXB-8000L," "EXB-8000L-65M," "EXB-8000L-65TM," "HPC-8000L-65TM," "HPC-8000," "HPC-8000-65T," "HPC-8000H," and "HPC-8000H-65TM" (manufactured by DIC Corporation); and active ester resins containing a naphthalene structure such as "HP-B-8151-62T," "EXB-8100L-65T," "EXB-8150-60T," and "EXB-8 Examples of such active ester resins include "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", and "EXB-8" (manufactured by DIC Corporation); an active ester resin containing phosphorus, such as "EXB9401" (manufactured by DIC Corporation); an active ester resin which is an acetylated product of phenol novolac, such as "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester resins which are benzoylated products of phenol novolac, such as "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and an active ester resin containing a styryl group and a naphthalene structure, such as "PC1300-02-65MA" (manufactured by Air Water Inc.).

[0051] The active ester group equivalent of the (B-1) active ester resin is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active ester group equivalent represents the mass of the resin per equivalent of the active ester group.

[0052] In one example, the range of the weight average molecular weight (Mw) of the (B-1) active ester resin may be the same as the range of the weight average molecular weight (Mw) of the (A) epoxy resin.

[0053] The amount of the (B-1) active ester resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more, relative to 100% by mass of the nonvolatile components in the resin composition, and is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. Conventionally, resin compositions containing such an amount of (B-1) active ester resin have tended to cause swelling in the bleed-out portion, but the resin composition according to this embodiment can suppress such swelling.

[0054] The amount of the (B-1) active ester resin is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Conventionally, resin compositions containing such an amount of (B-1) active ester resin have tended to cause swelling in the bleed-out portion, but the resin composition according to this embodiment can suppress such swelling.

[0055] When the number of epoxy groups in the (A) epoxy resin is taken as 1, the number of active ester groups in the (B-1) active ester resin is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and preferably 2.0 or less, more preferably 1.6 or less, even more preferably 1.3 or less. The "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the (A) epoxy resin present in the resin composition by the epoxy equivalent. Furthermore, the "number of active ester groups in the active ester resin" refers to the total value obtained by dividing the mass of the non-volatile components of the (B-1) active ester resin present in the resin composition by the active ester group equivalent.

[0056] The (B) curing agent may contain (B-2) an optional curing agent. The (B-2) optional curing agent refers to a curing agent other than the (B-1) active ester resin. Examples of the (B-2) optional curing agent include phenolic resins, cyanate ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among these, phenolic resins, cyanate ester resins, and carbodiimide resins are preferred, and phenolic resins are more preferred. The (B-2) optional curing agent may be used alone or in combination of two or more.

[0057] The phenolic resin may be a compound having one or more, preferably two or more, hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule. When combined with an epoxy resin, a phenolic resin may react with the epoxy resin to cure the resin composition, and is therefore sometimes referred to as a "phenolic curing agent." From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. Furthermore, from the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among these, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of achieving highly satisfactory heat resistance, water resistance, and adhesion.

[0058] Specific examples of phenolic resins include "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", and "SN- 375" and "SN-395" manufactured by DIC Corporation; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0059] The amount of the phenolic resin is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0060] The amount of the phenolic resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0061] (A) When the number of epoxy groups in the epoxy resin is taken as 1, the number of phenolic hydroxyl groups in the phenolic resin is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and preferably 1.5 or less, more preferably 1.0 or less, and particularly preferably 0.6 or less. The "number of phenolic hydroxyl groups in the phenolic resin" refers to the total value obtained by dividing the mass of the non-volatile components of the phenolic resin present in the resin composition by the phenolic hydroxyl group equivalent. The phenolic hydroxyl group equivalent refers to the mass of resin per equivalent of phenolic hydroxyl groups.

[0062] The cyanate ester resin may be a compound having one or more, preferably two or more, cyanate groups in one molecule. When combined with an epoxy resin, the cyanate ester resin reacts with the epoxy resin to cure the resin composition, and is therefore sometimes called a "cyanate ester curing agent." Examples of cyanate ester resins include bifunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl 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; multifunctional cyanate ester resins derived from phenol novolac, cresol novolac, and the like; and prepolymers in which these cyanate ester resins are partially triazine converted. Specific examples of cyanate ester resins include "PT30" and "PT60" (phenol novolac type multifunctional cyanate ester resins) manufactured by Arxada, "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine converted to a trimer).

[0063] As the carbodiimide resin, a compound having one or more, preferably two or more, carbodiimide structures in one molecule can be used. When combined with an epoxy resin, the carbodiimide resin reacts with the epoxy resin to harden the resin composition, and is therefore sometimes referred to as a "carbodiimide curing agent." Specific examples of carbodiimide resins include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-05," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Lanxess AG.

[0064] As the acid anhydride resin, a compound having one or more, preferably two or more, acid anhydride groups in one molecule can be used. When combined with an epoxy group, the acid anhydride resin can react with the epoxy resin to harden the resin composition, and therefore is sometimes called an "acid anhydride curing agent." Specific examples of acid anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable anhydrides include anhydrides, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Resonac Corporation; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Cray Valley Chemical Industries, Ltd.

[0065] The amine resin may be a compound having one or more, preferably two or more, amino groups in one molecule. When combined with an epoxy group, the amine resin may react with the epoxy resin to cure the resin composition, and is therefore sometimes referred to as an "amine curing agent." Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary amine or secondary amine, with primary amines being more preferred. Specific examples of amine-based resins include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propanol. Examples of suitable bis(4-aminophenoxy)benzene include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine-based resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0066] The benzoxazine resin may be a compound having one or more, preferably two or more, benzoxazine rings in one molecule. When combined with an epoxy resin, the benzoxazine resin reacts with the epoxy resin to cure the resin composition, and is therefore sometimes referred to as a "benzoxazine curing agent." Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0067] Thiol-based resins are sometimes called "thiol-based curing agents" because they react with epoxy resins when combined with them to cure the resin composition. Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0068] The active group equivalent of the optional curing agent (B-2) is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the resin per equivalent of the active group.

[0069] In one example, the range of the weight average molecular weight (Mw) of the (B-2) optional curing agent may be the same as the range of the weight average molecular weight (Mw) of the (A) epoxy resin.

[0070] In the resin composition according to this embodiment, the ratio M(B) / M(A), where M(B) is the number of active groups in the (B) curing agent and M(A) is the number of epoxy groups in the (A) epoxy resin, falls within a specific range. Specifically, the ratio M(B) / M(A) is typically 1.40 or greater, preferably 1.45 or greater, more preferably 1.50 or greater, even more preferably 1.55 or greater, and particularly preferably 1.60 or greater. To achieve significant benefits of the present invention, the upper limit is preferably 2.00 or less, more preferably 1.90 or less, and even more preferably 1.80 or less. As described above, the "number of epoxy groups in the epoxy resin" M(A) refers to the sum of all values ​​obtained by dividing the mass of the nonvolatile components of the (A) epoxy resin present in the resin composition by the epoxy equivalent. Furthermore, the "number of active groups in the curing agent" M(B) refers to the sum of all values ​​obtained by dividing the mass of the nonvolatile components of the (B) curing agent present in the resin composition by the active group equivalent. Conventionally, resin compositions having a ratio M(B) / M(A) in this range have yielded cured products with low dielectric tangent Df, but have tended to cause swelling in the bleed-out area. In contrast, the resin composition according to the present embodiment can suppress such swelling.

[0071] The amount of (B) curing agent is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, relative to 100% by mass of non-volatile components in the resin composition.

[0072] The amount of the curing agent is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, relative to 100% by mass of the resin component in the resin composition.

[0073] ((C) Explanation of inorganic filler) The resin composition according to the present embodiment preferably includes an inorganic filler (C) as component (C). The inorganic filler (C) is included in the resin composition in the form of particles, and is typically included in the cured product while maintaining this particle state. The inorganic filler (C) typically reduces the degree of thermal expansion and contraction of the cured product of the resin composition, resulting in an insulating layer with a low linear thermal expansion coefficient. However, resin compositions containing a large amount of inorganic filler (C) have a relatively small amount of resin components that can function as a binder. Therefore, when inorganic filler (C) is used, the ability to retain the shape of the cured product against the stress generated by the heat of the annealing treatment is further reduced, making swelling particularly likely to occur in the bleed-out area. The resin composition according to the present embodiment can suppress swelling in the bleed-out area even in such a configuration.

[0074] (C) Inorganic filler materials include inorganic compounds. Examples of (C) inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Therefore, (C) inorganic filler preferably contains silica, or may contain only silica. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Moreover, the silica is preferably spherical silica.The inorganic filler (C) may be used alone or in combination of two or more kinds.

[0075] (C) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," "YA010C," "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30," "DAW-03," and "FB-105FD" manufactured by Denka Company, Limited; "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation; and "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation.

[0076] The average particle size of the (C) inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less.

[0077] (C) The average particle size of an inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the inorganic filler is created using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The volumetric particle size distribution of the inorganic filler is measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0078] (C) The specific surface area of ​​the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, particularly preferably 3m 2 / g or more, preferably 100m 2 / g or less, more preferably 70m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 40m 2 The specific surface area of ​​the inorganic filler can be measured in accordance with the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0079] The (C) inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of the surface treatment agent include a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an alkoxysilane, an organosilazane compound, and a titanate coupling agent. One type of surface treatment agent may be used alone, or two or more types may be used in any combination.

[0080] Examples of commercially available surface treatment agents include Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical Co., Ltd.'s "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

[0081] The degree of surface treatment with the surface treatment agent preferably falls within a specific range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass of the surface treatment agent, and even more preferably with 0.3% to 2% by mass of the surface treatment agent.

[0082] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition, it is more preferable that the content be 1.0 mg / m 2 Preferably less than 0.8 mg / m 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0083] (C) The amount of carbon per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a 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. An "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used as the carbon analyzer.

[0084] The amount of the (C) inorganic filler is preferably 70% by mass or more, preferably 72% by mass or more, more preferably 74% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition. When the amount of the (C) inorganic filler is within the above range, the linear thermal expansion coefficient of the cured resin composition can be reduced. Furthermore, resin compositions containing an amount of the (C) inorganic filler within this range have traditionally tended to cause swelling in the bleed-out area. In contrast, the resin composition of the present embodiment can suppress swelling in the bleed-out area, even while containing such an amount of the (C) inorganic filler.

[0085] (D) Description of organic filler The resin composition according to this embodiment may contain an organic filler (D) as an optional component. The organic filler (D) as component (D) does not include components (A) to (C) described above. The organic filler (D) is contained in the resin composition in the form of particles, and is usually contained in the cured product while maintaining this particulate state. The organic filler (D) improves the thixotropy of the resin composition during lamination, thereby suppressing exudation of the resin composition layer from the gap between the inner layer substrate and the support. This makes it possible to reduce the area of ​​the bleed-out portion. One type of organic filler (D) may be used alone, or two or more types may be used in combination.

[0086] Examples of the (D) organic filler include rubber particles, polyamide fine particles, silicone particles, core-shell particles, etc. Among these, it is preferable to use either rubber particles or core-shell particles, and it is more preferable to use core-shell particles.

[0087] Examples of rubber components contained in the rubber particles include thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and acrylic thermoplastic elastomers such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, and polyoctyl(meth)acrylate. The term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof, unless otherwise specified. Among these, olefin-based thermoplastic elastomers are preferred, and styrene-butadiene copolymers are more preferred. Silicone-based rubbers such as polyorganosiloxane rubbers may also be mixed with the rubber component. The rubber component contained in the rubber particles usually has a glass transition temperature of 0°C or lower, preferably -10°C or lower, more preferably -20°C or lower, and even more preferably -30°C or lower.

[0088] As the rubber particles, commercially available products may be used, such as "EXL2655" manufactured by Dow Chemical Japan, and "AC3401N" and "AC3816N" manufactured by Aica Kogyo Co., Ltd.

[0089] Core-shell particles are particulate organic fillers comprising a core particle and one or more shell layers covering the core particle. The core particle preferably contains the rubber component described above. The shell preferably contains an appropriate polymer. The core-shell particles are preferably core-shell graft copolymer particles consisting of a core particle containing a rubber component and a shell obtained by graft copolymerization of a monomer component copolymerizable with the rubber component contained in the core particle. The term "core-shell" as used here does not necessarily refer only to particles in which the core particle and the shell are clearly distinguishable, but also includes particles in which the boundary between the core particle and the shell is unclear. The core particle may or may not be completely covered by the shell.

[0090] The amount of core particles contained in the core-shell particles is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on 100% by mass of the core-shell particles. The upper limit is not particularly limited, but may be, for example, 95% by mass or less, 90% by mass or less, from the viewpoint of sufficiently covering the core particles with the shell portion.

[0091] Examples of monomer components for the polymer forming the shell portion include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, and glycidyl (meth)acrylate; (meth)acrylic acid; N-substituted maleimides such as N-methylmaleimide and N-phenylmaleimide; maleimide; α,β-unsaturated carboxylic acids such as maleic acid and itaconic acid; aromatic vinyl compounds such as styrene, 4-vinyltoluene, and α-methylstyrene; and (meth)acrylonitrile. Among these, (meth)acrylic acid esters are preferred, and methyl (meth)acrylate is more preferred. One type of monomer component may be used alone, or two or more types may be used in combination.

[0092] Commercially available core-shell particles may be used. For example, commercially available core-shell graft copolymer particles include "CHT" manufactured by Samsung SDI Corporation; "B602" manufactured by Techno UMG Corporation; "Paraloid EXL-2602," "Paraloid EXL-2603," "Paraloid EXL-2655," "Paraloid EXL-2311," "Paraloid EXL-2313," "Paraloid EXL-2315," "Paraloid KM-330," and "Paraloid KM-3311" manufactured by Dow Chemical Japan. Examples include Pararoid KM-336P and Pararoid KCZ-201; Mitsubishi Rayon's Metablen C-223A, Metablen E-901, Metablen S-2001, Metablen W-450A, and Metablen SRK-200; and Kaneka's Kane Ace M-511, Kane Ace M-600, Kane Ace M-400, Kane Ace M-580, and Kane Ace MR-01.

[0093] The average particle size (average primary particle size) of the (D) organic filler is not particularly limited, but is preferably 20 nm or more, more preferably 50 nm or more, even more preferably 80 nm or more, and even more preferably 100 nm or more, and is preferably 5,000 nm or less, more preferably 2,000 nm or less, even more preferably 1,000 nm or less, and even more preferably 500 nm or less. The average particle size (average primary particle size) of the (D) organic filler can be measured using a zeta potential particle size distribution measuring device.

[0094] The amount of (D) organic filler is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, relative to 100% by mass of the nonvolatile components in the resin composition, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, even more preferably 1% by mass or less.

[0095] The amount of (D) organic filler is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0096] ((E) Explanation of hardening accelerator) The resin composition according to the present embodiment may contain a curing accelerator (E) as an optional component. The curing accelerator (E) as component (E) does not include components (A) to (D) described above. The curing accelerator (E) acts as a catalyst for the reaction of the epoxy resin (A) to accelerate the curing of the resin composition.

[0097] Examples of the (E) curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, etc. One type of (E) curing accelerator may be used alone, or two or more types may be used in combination.

[0098] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0099] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0100] Examples of guanidine 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, and 1-(o-tolyl)biguanide.

[0101] Examples of the imidazole curing accelerator 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, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium 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 Examples of imidazole compounds include 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, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Commercially available imidazole curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0102] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0103] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Commercially available amine curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0104] The amount of (E) curing accelerator is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, relative to 100% by mass of non-volatile components in the resin composition.

[0105] The amount of (E) curing accelerator is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1.0% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less.

[0106] ((F) Description of optional additives) The resin composition may further contain (F) optional additives as an optional component. The (F) optional additives as component (F) do not include those corresponding to the above-mentioned components (A) to (E). (F) Optional additives include, for example, radical polymerizable resins such as acrylic resins, styryl resins, allyl resins, and maleimide resins; radical polymerization initiators such as peroxide radical polymerization initiators and azo radical polymerization initiators; organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt 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 leveling agents and acrylic polymer leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone antifoaming agents, acrylic antifoaming agents, fluorine-based antifoaming agents, and vinyl resin antifoaming agents; ultraviolet absorbers such as benzotriazole ultraviolet absorbers; and adhesive agents such as urea silane. Examples of the additives include adhesion improvers, adhesion promoters such as triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters, 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, and red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic 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, and 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. (F) Optional additives may be used alone or in combination of two or more.

[0107] (G) Solvent Description The resin composition may further contain a (G) solvent as an optional volatile component in addition to the non-volatile components (A) to (F) described above. An organic solvent is typically used as the (G) solvent. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of suitable solvents include ether ester solvents such as ethyl acetate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (G) Solvents may be used singly or in combination of two or more.

[0108] Usually, all or most of the (G) solvent is removed by drying during the production process of the resin composition. Therefore, the resin composition may not contain the (G) solvent. Furthermore, when the resin composition contains the (G) solvent, it is preferable that the amount of the (G) solvent is small. It is preferable that the specific amount of the (G) solvent is set so that the above-mentioned requirement (R) is satisfied.

[0109] (Characteristics of resin composition) The resin composition may have a low minimum melt viscosity. The range of the minimum melt viscosity of the resin composition is preferably 10,000 poise or less, more preferably 9,000 poise or less, and even more preferably 7,000 poise or less. A resin composition having a low minimum melt viscosity can satisfactorily embed the conductor layer and components provided on the surface of the inner layer substrate, but is prone to exudation of the resin composition layer, resulting in the formation of a bleed-out portion. However, even when such a bleed-out portion is formed, the resin composition according to this embodiment can suppress swelling of the bleed-out portion. From the viewpoint of smoothly forming a resin composition layer of the desired thickness, the lower limit of the minimum melt viscosity is preferably 200 poise or more, more preferably 500 poise or more. The minimum melt viscosity of the resin composition can be measured using a dynamic viscoelasticity measuring device. Specifically, the minimum melt viscosity can be determined by measuring the dynamic viscoelastic modulus of a sample at a temperature rise rate of 5°C / min within a temperature range from a starting temperature of 60°C to 200°C, with a measurement temperature interval of 2.5°C, a vibration frequency of 1 Hz, and a strain of 5 deg. The specific method for measuring the minimum melt viscosity may be the method described in "Measurement of minimum melt viscosity of resin composition" in the Examples section below.

[0110] By curing the resin composition, a cured product of the resin composition can be obtained. An insulating layer can be formed from this cured product. During the curing process, heat is usually applied to the resin composition layer, and the volatile component (F) of the resin composition, which is a solvent, can volatilize due to the heat generated during curing. Therefore, the cured product of the resin composition can contain the non-volatile components of the resin composition or their reaction products.

[0111] Generally, in a method for manufacturing a circuit board using a resin composition, the resin composition is cured to form an insulating layer, a conductor layer is formed on the insulating layer, and then an annealing process is performed to heat the insulating layer and the conductor layer. Typically, prior to this annealing process, the cured resin composition contained in the insulating layer is in a semi-cured state, in which the curing reaction has not yet been completed. It is believed that the swelling of the bleed-out portion caused by the annealing process in the past occurred because such a semi-cured cured product contains components that can be vaporized by heat. In this embodiment, even when the bleed-out portion of the insulating layer is formed from such a semi-cured cured product, swelling of the bleed-out portion can be suppressed.

[0112] The cured product obtained by curing the resin composition according to this embodiment typically has a low dielectric loss tangent Df. Therefore, this resin composition can form an insulating layer with a low dielectric loss tangent Df. In one example, the dielectric loss tangent of the cured product is preferably 0.020 or less, more preferably 0.010 or less, and even more preferably 0.005 or less. There is no particular lower limit, and the dielectric loss tangent can be, for example, 0.0001 or more. The dielectric loss tangent can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. When the sample is a resin composition before curing, the resin composition is cured at 190°C for 90 minutes to obtain a cured product, and the dielectric loss tangent of the cured product can be measured. The dielectric loss tangent can be measured as described in the "Dielectric Loss Tangent Measurement Test" section of the Examples below.

[0113] The cured product obtained by curing the resin composition according to this embodiment typically has a small coefficient of linear thermal expansion. Therefore, this resin composition can form an insulating layer with a small coefficient of linear thermal expansion, thereby suppressing warpage of the circuit board. The average coefficient of linear thermal expansion (CTE) of the cured product is preferably 100 ppm / °C or less, more preferably 50 ppm / °C or less, and even more preferably 30 ppm / °C or less. The lower limit is not particularly limited, but may be, for example, 0.01 ppm / °C or more. The average coefficient of linear thermal expansion (CTE) can be measured in the temperature range of 25°C to 150°C by thermomechanical analysis at a heating rate of 5°C / min from 25°C to 250°C. When the sample is a resin composition before curing, the resin composition is cured under curing conditions of 190°C for 90 minutes to obtain a cured product, and the average coefficient of linear thermal expansion (CTE) of the cured product can be measured. The specific method for measuring the average coefficient of linear thermal expansion (CTE) can be the method described in the "Measurement Test for the Average Coefficient of Linear Thermal Expansion (CTE)" section of the Examples below.

[0114] (Method of producing resin composition) The resin composition can be produced by mixing components that can be contained in the resin composition. The above-mentioned components may be mixed in part or all at the same time, or may be mixed sequentially. In the process of mixing each component, the temperature may be appropriately set, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed in the process of mixing each component.

[0115] The resin composition may be produced by preparing a resin varnish containing (A) an epoxy resin, (B) a curing agent, and (G) a solvent, and then drying the resin varnish to remove the (G) solvent. The resin varnish may further contain optional non-volatile components such as components (C) to (F). Typically, the non-volatile components of the resin varnish have the same composition as the non-volatile components of the resin composition. For example, after preparing the resin varnish, the resin varnish may be applied to a support and dried to produce a resin composition layer.

[0116] The drying conditions are preferably set so as to obtain a mass loss rate that satisfies the above-mentioned requirement (R). In one example, the drying temperature is preferably 40°C or higher, more preferably 50°C or higher, even more preferably 60°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, even more preferably 130°C or lower. The drying time is preferably 60 seconds or longer, more preferably 90 seconds or longer, even more preferably 120 seconds or longer, and preferably 10 minutes or shorter, more preferably 8 minutes or shorter, even more preferably 6 minutes or shorter.

[0117] (Uses of resin composition) The resin composition according to this embodiment can be used to form an insulating layer, and is particularly preferably used to form an insulating layer for a circuit board. The resin composition can also be used to manufacture a resin sheet. Typically, an insulating layer is formed using this resin sheet. The resin composition may also be used for other purposes, such as a solder resist, an underfill material, a die bonding material, a hole filling resin, a sealing resin, or a component embedding resin.

[0118] <Resin sheet> A resin sheet according to one embodiment of the present invention includes a support and a resin composition layer formed on the support. The resin composition layer contains the resin composition described above, and preferably contains only the resin composition described above.

[0119] Since the resin composition layer contains the resin composition described above, when an evaluation test relating to requirement (R) is performed using the resin composition layer of the resin sheet, a mass loss rate within a range that satisfies requirement (R) is obtained. That is, as explained in the section on resin composition, when an evaluation test is performed in which a test layer obtained by heating the resin composition layer of the resin sheet at 130°C for 30 minutes and at 170°C for 30 minutes is heated at 175°C for 30 minutes, the mass loss rate of the test layer after heating at 175°C for 30 minutes is within a specific range of 3% or less. The evaluation test can be performed using the method explained in the section on resin composition.

[0120] This resin sheet can suppress swelling at the bleed-out portion. Furthermore, it is usually possible to obtain an insulating layer with a low dielectric tangent. Furthermore, this resin sheet can provide the same advantages as the resin composition described above.

[0121] From the viewpoint of thinning, the thickness of the resin composition layer provided in the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0122] Examples of the support include plastic film, metal foil, and release paper, with plastic film and metal foil being preferred.

[0123] When a film 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"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0124] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0125] The surface of the support that is to be bonded to the resin composition layer may be subjected to a surface treatment such as matte treatment, corona treatment, or antistatic treatment.

[0126] The support may be a support with a release layer, which has a release layer on the surface that bonds with the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, and silicone-based release agents. Commercially available products may be used as the support with a release layer, including PET films having a release layer primarily composed of a silicone-based release agent or an alkyd resin-based release agent, such as "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Limited.

[0127] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is within the above range.

[0128] The resin sheet may include any optional member as needed. For example, the resin sheet may include a protective film for protecting the resin composition layer. The protective film is usually provided on the surface of the resin composition layer that is not bonded 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. When the protective film is provided, adhesion of dust and scratches to the surface of the resin composition layer can be suppressed.

[0129] The resin sheet can be produced, for example, by a method including forming a resin composition layer on a support. For example, the resin sheet may be produced by a production method including, in this order, the steps of preparing a resin varnish described in the section on the method for producing a resin composition, applying the resin varnish to a support, and drying the applied resin varnish to form a resin composition layer.

[0130] The resin varnish can be applied using a coating device such as a die coater. Drying can be performed by, for example, heating, hot air blowing, or other drying methods. The drying conditions are preferably set so as to obtain a mass loss rate that satisfies the above-mentioned requirement (R). The drying conditions, such as the drying temperature and drying time, may be the same as those described in the section on the method for producing the resin composition.

[0131] The produced resin sheet can be stored by being wound up in a roll. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0132] <Circuit board> A circuit board according to one embodiment of the present invention includes a cured product of the resin composition described above. Typically, the circuit board includes an insulating layer, and this insulating layer includes a cured product of the resin composition. The insulating layer may include only a cured product of the resin composition. The thickness of the insulating layer is not particularly limited and may be, for example, in the same range as the thickness of the resin composition layer included in the resin sheet.

[0133] Preferably, the circuit board includes an inner layer substrate and the insulating layer is provided on the inner layer substrate. The circuit board may also include a conductor layer. For example, the conductor layer may be provided on an insulating layer. An example of a preferred method for manufacturing a circuit board will be described below.

[0134] A preferred example of a method for manufacturing a circuit board includes the steps of: a step (I) of laminating an inner layer substrate and a resin sheet so that the inner layer substrate and the resin composition layer are bonded to each other; a step (II) of curing the resin composition layer; Includes.

[0135] A preferred example of a method for manufacturing a circuit board includes a step (I) of laminating a resin sheet and an inner layer substrate. The resin sheet and the inner layer substrate are laminated so that the resin composition layer of the resin sheet and the inner layer substrate are bonded. This lamination forms a resin composition layer on the inner layer substrate.

[0136] An "inner layer substrate" is a member that serves as the base material of a circuit board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate may have a conductor layer on one or both sides. The conductor layer of the inner layer substrate may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." The term "inner layer substrate" also includes intermediate products on which insulating layers and / or conductor layers are to be further formed during the production of a circuit board. In addition, inner layer substrates with built-in components may also be used.

[0137] The inner layer substrate and the resin sheet can be laminated, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of the member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as the "thermocompression bonding member") include a heated metal plate (such as a SUS plate) or a metal roll (such as a SUS roll). Note that rather than pressing the thermocompression bonding member directly onto the resin sheet, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the inner layer substrate.

[0138] The inner layer substrate and the resin sheet may be laminated by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions of 26.7hPa or less.

[0139] Lamination can be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0140] FIG. 1 is a schematic cross-sectional view illustrating a method for manufacturing a circuit board according to one embodiment of the present invention. As shown in FIG. 1, when laminating an inner substrate 100 and a resin sheet 200, most of the resin composition layer 210 is provided in a gap 300 between the inner substrate 100 and the support 220, but a portion 230 of the resin composition layer 210 seeps out of the gap 300. Thus, step (I) involves the portion 230 of the resin composition layer 210 seeping out of the gap 300. This seeped portion 230 forms a bleed-out portion. In the following description, the bleed-out portion will be denoted by the same reference numeral "230" as the portion 230 of the resin composition layer 210 seeping out of the gap 300. By using the resin composition described above, swelling of the bleed-out portion 230 can be suppressed.

[0141] The method for manufacturing a circuit board shown in this example may include smoothing the resin sheet after lamination under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing may be the same as the conditions for thermocompression bonding of the lamination. The smoothing may be performed using a commercially available laminator. The lamination and smoothing may be performed consecutively using the commercially available vacuum laminator.

[0142] The method for producing a circuit board according to this example includes a step (II) of curing the resin composition layer after the step (I). By curing the resin composition layer in the step (II), an insulating layer can be formed.

[0143] Specific curing conditions for the resin composition layer may be those typically employed when forming an insulating layer for a circuit board. Typically, curing of a resin composition proceeds by thermal curing. Therefore, step (II) may include thermally curing the resin composition layer. The thermal curing conditions for the resin composition layer may vary depending on the type of resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. The curing time is preferably 5 to 120 minutes, more preferably 10 to 100 minutes, and even more preferably 15 to 100 minutes.

[0144] Furthermore, when the resin composition layer is thermally cured, the method for producing a circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before the thermal curing. For example, prior to thermal curing of the resin composition layer, the resin composition layer may be preheated for typically 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes, at a temperature of typically 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C. Preheating is typically performed after step (I). Furthermore, when a smoothing treatment is performed after laminating the inner layer substrate and the resin sheet, preheating can be performed after the smoothing treatment.

[0145] The method for producing a circuit board shown in this example may include a step of peeling off the support of the resin sheet after laminating the inner layer substrate and the resin sheet. Peeling off the support may be performed between steps (I) and (II), or after step (II). Furthermore, when the method for producing a circuit board includes step (III) of forming holes in the insulating layer, step (IV) of roughening the insulating layer, and step (V) of forming a conductor layer, as described below, peeling off the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V).

[0146] The method for producing a circuit board according to this example may include a step (III) of forming holes such as via holes or through holes in the insulating layer after step (II). The method for forming the holes may be selected depending on factors such as the composition of the resin composition used to form the insulating layer. For example, holes may be formed by processing methods such as drilling, laser processing, and plasma processing, with laser processing being preferred among them. For example, holes may be formed by irradiating the insulating layer with laser light after peeling off the support, or by irradiating the insulating layer with laser light through the support. The dimensions and shape of the holes may be determined appropriately depending on the design of the circuit board.

[0147] The method for manufacturing a circuit board according to this embodiment may include a step (IV) of roughening the insulating layer. The roughening treatment can roughen the surface of the insulating layer. Furthermore, the roughening treatment can remove smears (resin residues) from the insulating layer. Therefore, this roughening treatment is sometimes called a "desmear treatment." For example, when holes are formed in step (III), smears may form in the holes. Therefore, it is preferable to perform the roughening treatment of step (IV) after step (III) to remove the smears.

[0148] The procedure and conditions for the roughening treatment are not particularly limited, and known procedures and conditions that are commonly used when forming an insulating layer for a circuit board can be adopted. For example, the roughening treatment may be performed by subjecting the insulating layer to a swelling treatment using a swelling liquid, an oxidation treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid in this order.

[0149] Examples of swelling liquids used in the roughening treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Examples of the alkaline solution include sodium hydroxide solution and potassium hydroxide solution. Examples of commercially available swelling liquids include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. Swelling treatment using a swelling liquid can be performed by immersing the insulating layer in the swelling liquid at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in the swelling liquid at 40°C to 80°C for 5 to 15 minutes.

[0150] Examples of oxidizing agents used in the roughening treatment include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Oxidation treatment using an oxidizing agent such as alkaline permanganate solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0151] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan can be cited as an example. Neutralization treatment using a neutralizing solution can be carried out by immersing the surface that has been oxidized with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, a preferred method is to immerse the object that has been oxidized with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0152] The method for producing a circuit board according to this embodiment may include a step (V) of forming a conductor layer on an insulating layer. When the method for producing a circuit board includes the steps (III) or (IV), the step (V) of forming a conductor layer is usually preferably carried out after the steps (III) and (IV).

[0153] The conductive material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor 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 conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy are preferred. Single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy are more preferred, and single metal layers of copper are even more preferred.

[0154] The conductor layer may have a single layer structure or a multi-layer structure including two or more single metal or alloy layers made of different types of metals or alloys. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0155] The thickness of the conductor layer depends on the design of the circuit board, but is preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

[0156] The conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventionally known technique such as a semi-additive method or a full-additive method. From the viewpoint of ease of production, the semi-additive method is preferred. An example of forming a conductor layer by a semi-additive method will be described below.

[0157] First, an electroless plated layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plated layer, exposing a portion of the electroless plated layer corresponding to the desired wiring pattern. After forming an electroless plated layer on the exposed electroless plated layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary electroless plated layer is removed by etching, thereby forming a conductor layer having the desired wiring pattern.

[0158] When a conductor layer is formed on an insulating layer, the manufacturing method of a circuit board usually includes performing an annealing treatment after the formation of the conductor layer. The annealing treatment can improve the adhesion between the insulating layer and the conductor layer. Furthermore, while the heat of the annealing treatment has conventionally caused swelling in the bleed-out portion, this embodiment can suppress swelling in the bleed-out portion. The annealing treatment can be performed, for example, by heating at 150°C to 210°C for 20 to 180 minutes.

[0159] In the method for manufacturing a circuit board, each of the above steps may be performed only once or may be repeated two or more times. For example, steps (I) to (V) may be performed repeatedly to form a circuit board having a multilayer structure, such as a multilayer printed wiring board having a plurality of insulating layers and conductor layers.

[0160] The method for manufacturing a circuit board may further include any optional steps in addition to the steps described above. For example, the method for manufacturing a circuit board may include a step of providing a semiconductor chip so that the semiconductor chip is bonded to the conductor layer. Specifically, when manufacturing a circuit board for a semiconductor chip package including a semiconductor chip, the method for manufacturing a circuit board may include a step of providing the semiconductor chip. The semiconductor chip may be bonded under appropriate conditions that allow conductive connection between the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer. For example, conditions used in flip-chip mounting may be employed. The semiconductor chip may be bonded via an insulating adhesive or by reflow bonding. If necessary, the provided semiconductor chip may be filled with a mold underfill material. The method for manufacturing a circuit board may also include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, and a step of dicing the manufactured circuit board into individual pieces.

[0161] Examples of circuit boards include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA package, ETS-BGA package, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to form a rewiring formation layer using an insulating layer obtained by curing the above-mentioned resin composition layer. However, the circuit board is not limited to those exemplified here.

[0162] <Semiconductor device> The circuit board can be used to manufacture a semiconductor device. The semiconductor device includes the circuit board described above. Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0163] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, the temperature and pressure conditions were room temperature (23°C) and atmospheric pressure (1 atm), unless otherwise specified.

[0164] <Synthesis Example 1: Synthesis of active ester compound (A2)> A flask equipped with a thermometer, dropping funnel, condenser, distillation column, and stirrer was charged with 320 g (2.0 mol) of 2,7-dihydroxynaphthalene, 184 g (1.7 mol) of benzyl alcohol, and 5.0 g of paratoluenesulfonic acid monohydrate. The mixture was stirred at room temperature while blowing in nitrogen. The temperature was then raised to 150 °C and the mixture was stirred for 4 hours while distilling off the resulting water. After the reaction was complete, 900 g of methyl isobutyl ketone and 5.4 g of 20% aqueous sodium hydroxide solution were added to neutralize the mixture. The aqueous layer was then removed by separation. The mixture was washed three times with 280 g of water, and the methyl isobutyl ketone was removed under reduced pressure to obtain 460 g of benzyl-modified naphthalene compound (A1). The resulting benzyl-modified naphthalene compound (A1) was a black solid with a hydroxyl equivalent of 180 g / eq.

[0165] A flask equipped with a thermometer, dropping funnel, condenser, distillation column, and stirrer was charged with 203.0 g of isophthalic acid chloride (molar number of acid chloride groups: 2.0 mol) and 1400 g of toluene, and the system was purged with nitrogen under reduced pressure to allow dissolution. Next, 113.9 g (0.67 mol) of orthophenylphenol and 240 g of benzyl-modified naphthalene compound (A1) (molar number of phenolic hydroxyl groups: 1.33 mol) were charged, and the system was purged with nitrogen under reduced pressure to allow dissolution. Then, 0.70 g of tetrabutylammonium bromide was dissolved, and while purging with nitrogen gas, the system was controlled to below 60°C, and 400 g of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was then continued under these conditions for 1.0 hour. After completion of the reaction, the mixture was allowed to stand for separation, and the aqueous layer was removed. Water was then added to the toluene layer containing the dissolved reactant, and the mixture was stirred and mixed for 15 minutes. The mixture was then allowed to stand and separated, and the aqueous layer was removed. This procedure was repeated until the pH of the aqueous layer reached 7. The water was then removed by decanting, yielding an active ester compound (A2) in the form of a toluene solution containing 65% by mass of nonvolatile components. The active ester equivalent of the resulting active ester compound (A2) was 238 g / eq.

[0166] <Explanation of Examples 1 to 4 and Comparative Examples 1 to 4> The components were weighed in the amounts shown in Tables 1 and 2 below, mixed, and uniformly dispersed using a high-speed rotary mixer to obtain a resin varnish. The amount of each component shown in Tables 1 and 2 is expressed in parts by mass. Details of each component shown in Tables 1 and 2 are as follows:

[0167] (A) Epoxy resin HP-4032-SS: Naphthalene-type epoxy resin, epoxy equivalent 144g / eq., manufactured by DIC Corporation NC-3000L: Biphenyl type epoxy resin, epoxy equivalent 270g / eq., manufactured by Nippon Kayaku Co., Ltd.

[0168] (B-1) Active ester resin: HPC-8150-62T: Active ester equivalent weight 230 g / eq., non-volatile content 61.5% by mass in toluene solution, manufactured by DIC Corporation Active ester compound (A2): Synthesized in Synthesis Example 1. Active ester group equivalent weight 238 g / eq., toluene solution with non-volatile components of 65% by mass

[0169] (C) Optional hardener: LA-3018-50P: Phenolic resin, phenolic hydroxyl equivalent 151g / eq., 1-methoxy-2-propanol solution containing 50% non-volatile matter, manufactured by DIC Corporation

[0170] (D) Inorganic filler: SO-C2: Spherical silica surface-treated with an amine-based alkoxysilane compound ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), average particle size 0.5 μm, specific surface area 5.8 m 2 / g, manufactured by Admatechs Co., Ltd.

[0171] (E) Organic filler: EXL-2655: Core-shell particles containing rubber components in the core, manufactured by Dow

[0172] (F) Curing accelerator: 1B2PZ: Imidazole curing accelerator, manufactured by Shikoku Chemicals Corporation

[0173] (E) Solvent: MEK: Methyl ethyl ketone IP150: Solvent naphtha, manufactured by Idemitsu Kosan

[0174] <Manufacturing of resin sheets> A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) with a release layer was prepared as a support. The resin varnish was uniformly applied onto the release layer of this support so that the thickness of the resin composition layer after drying would be 40 μm. The applied resin varnish was then dried at 100°C for the drying time shown in Tables 1 and 2 to obtain a resin sheet A having a support and a resin composition layer containing a resin composition.

[0175] <Dielectric loss tangent measurement test> The resin sheet A obtained in each of the examples and comparative examples was heated in an oven at 190°C for 90 minutes to cure the resin composition layer. The support was then peeled off to obtain a cured product of the resin composition layer. The cured product was cut into a length of 80 mm and a width of 2 mm to obtain a cured product for evaluation.

[0176] For each cured evaluation product, the dielectric loss tangent (Df value) was measured using a measuring device (Agilent Technologies "HP8362B") by the cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. Measurement was performed on two cured evaluation products, and the average was calculated.

[0177] <Measurement test of mean coefficient of linear thermal expansion (CTE)> The resin sheet A obtained in each of the examples and comparative examples was heated in an oven at 190°C for 90 minutes to cure the resin composition layer. The support was then peeled off to obtain a cured product of the resin composition layer. The cured product was cut into a length of 20 mm and a width of 6 mm to obtain a test piece.

[0178] Each test piece was subjected to thermomechanical analysis using a TMA device (thermomechanical analyzer, manufactured by Rigaku Corporation) at a temperature increase rate of 5°C / min from 25°C to 250°C to measure the average coefficient of thermal expansion CTE [ppm / °C] in the range from 25°C to 150°C. The same test piece was measured twice, and the second value was recorded.

[0179] <Mass loss rate evaluation test> A polyimide film (UBE Corporation U-Plex, thickness 50 μm) was prepared as an inner layer substrate. Resin sheet A obtained in the examples and comparative examples was cut to a size of 490 mm length x 320 mm width. Using a batch-type vacuum pressure laminator (Nikko Materials Corporation, two-stage build-up laminator "CVP700"), resin sheet A was laminated onto the polyimide film so that the resin composition layer was in contact with the polyimide film, yielding an intermediate laminate having a layer structure of inner layer substrate / resin composition layer / support. This laminate was then depressurized for 30 seconds to adjust the air pressure to 13 hPa or less, and then heated at 100°C under a pressure of 7 kgf / cm. 2The resin sheet A was laminated with the polyimide film in this manner, thereby achieving lamination of the resin composition layer with the polyimide film.

[0180] The intermediate laminate was then placed in a 130°C oven and heated for 30 minutes, then transferred to a 170°C oven and heated for 30 minutes. The intermediate laminate was cut into a 10 cm square, and the support was peeled off to obtain a laminate sample comprising a polyimide film and a test layer. Because the resin composition cured by heating at 130°C for 30 minutes and 170°C for 30 minutes, the test layer contained a semi-cured cured product of the resin composition. The mass W0 of the test layer included in this laminate sample was measured. The polyimide film used as the inner layer substrate did not undergo mass change due to heating in the evaluation test. Therefore, the mass W0 of the test layer was calculated by measuring the mass of the laminate sample and subtracting the mass of a 10 cm square polyimide film, which had been measured in advance.

[0181] The laminated sample was then heated in an oven at 175°C for 30 minutes and allowed to cool in a desiccator. After cooling, the mass W1 of the test layer included in the laminated sample was measured. The mass W1 of the test layer was determined by measuring the mass of the laminated sample and subtracting the mass of a 10 cm square polyimide film, which had been measured in advance.

[0182] The mass loss rate was calculated by the following formula (M1) using the mass W0 of the test layer before heating and the mass W1 of the test layer after heating. Mass reduction rate (%)=(W0-W1) / W0×100 (M1)

[0183] <Manufacturing test of evaluation boards equivalent to circuit boards> (1) Preparation of inner layer board: Both sides of a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R1515A", substrate dimensions 510 mm × 340 mm) with an inner layer circuit formed on it were etched 1 μm in the thickness direction using a microetching agent (MEC "CZ8101") to roughen the copper surface.

[0184] (2) Lamination of resin sheet A: Resin sheet A was cut to a size of 490 mm x 320 mm. The resin sheet A thus cut was laminated onto both sides of the inner layer substrate using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700") so that the resin composition layer was in contact with the inner layer substrate. This lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then heating at 120°C and a pressure of 10 kgf / cm. 2 Then, the adhesive was applied at 120°C and a pressure of 14 kgf / cm for 30 seconds. 2 The laminate was then heat-pressed for 60 seconds at 100° C. Due to the lamination and heat-pressing, a part of the resin composition layer oozed out from the gap between the inner layer substrate and the support, forming a bleed-out portion.

[0185] (3) Thermal curing of the resin composition layer: The inner layer substrate laminated with resin sheet A was then placed in a 130°C oven and heated for 30 minutes, and then transferred to a 170°C oven and heated for 30 minutes to thermally cure the resin composition layer and form an insulating layer. The resulting insulating layer was in a semi-cured state, where the resin composition had partially cured. The support was then peeled off to obtain cured substrate A having the insulating layer, inner layer substrate, and insulating layer in this order.

[0186] (4) Roughening treatment: A desmear treatment as a roughening treatment was performed on the cured substrate A. The desmear treatment was the following wet desmear treatment.

[0187] Cured Substrate A was immersed in a swelling solution (Atotech Japan's "Swelling Dip Securigant P," an aqueous solution of diethylene glycol monobutyl ether and sodium hydroxide) at 60°C for 5 minutes. It was then immersed in an oxidizing solution (Atotech Japan's "Concentrate Compact CP," an aqueous solution of approximately 6% potassium permanganate and 4% sodium hydroxide) at 80°C for 20 minutes. It was then immersed in a neutralizing solution (Atotech Japan's "Reduction Solution Securigant P," an aqueous sulfuric acid solution) at 40°C for 5 minutes. It was then dried at 80°C for 15 minutes.

[0188] (5) Formation of the conductor layer: A conductor layer was formed on the roughened surface (roughened surface) of the insulating layer using a semi-additive process. Specifically, the roughened cured substrate A was immersed in an electroless plating solution containing PdCl2 at 40°C for 5 minutes. The cured substrate A was then immersed in an electroless copper plating solution at 25°C for 20 minutes to form an electroless plated layer. Next, the cured substrate A was annealed by heating at 150°C for 30 minutes, after which an etching resist was formed on the electroless plated layer and a pattern was formed by etching. Subsequently, copper sulfate electroplating was performed to form an electrolytic plated layer on the electroless plated layer, resulting in a conductor layer with a thickness of 25 μm, including the electroless plated layer and the electrolytic plated layer. The substrate was then annealed by heating at 190°C for 60 minutes to completely cure the resin composition in the insulating layer, yielding an evaluation substrate.

[0189] The bleed-out portion formed at the end of the insulating layer of the evaluation substrate was visually observed to check for the presence or absence of swelling in the bleed-out portion.

[0190] <Measurement of minimum melt viscosity of resin composition> A measurement sample was prepared by extracting 1.0 g of resin composition from the resin composition layer of the resin sheet A obtained in the Examples and Comparative Examples. The minimum melt viscosity of the obtained measurement sample was measured using a dynamic viscoelasticity measuring device (Rheosol-G3000 manufactured by UBM). Specifically, the measurement sample was heated in a temperature range from a starting temperature of 60°C to 200°C, and the dynamic viscoelastic modulus of the measurement sample was measured, and the minimum melt viscosity (poise) was calculated. The measurement conditions were a temperature rise rate of 5°C / min, a measurement temperature interval of 2.5°C, a vibration frequency of 1 Hz, and a strain of 5°.

[0191] <Result> The results of the above-mentioned Examples and Comparative Examples are shown in Tables 1 and 2 below.

[0192] [Table 1]

[0193] [Table 2] [Explanation of symbols]

[0194] 100 Inner layer board 200 Resin Sheet 210 Resin composition layer 220 Support 230 Bleed-out portion (part of the resin composition layer) 300 Gap

Claims

1. A resin composition comprising (A) an epoxy resin and (B) a curing agent; (B) the curing agent contains an active ester resin; the ratio M(B) / M(A) of the number of active groups in the (B) curing agent to the number of epoxy groups in the (A) epoxy resin, M(B) / M(A), is 1.4 or more; A resin composition, wherein when a test layer obtained by heating a resin composition layer formed from the resin composition at 130°C for 30 minutes and 170°C for 30 minutes is heated at 175°C for 30 minutes, an evaluation test is conducted in which the mass loss rate of the test layer due to heating at 175°C for 30 minutes is 3% or less.

2. The evaluation test forming a resin composition layer on a support using the resin composition; laminating the resin composition layer and the inner layer substrate; The resin composition layer is heated at 130°C for 30 minutes and 170°C for 30 minutes, and the support is peeled off to obtain a test layer; and Heating the test layer at 175°C for 30 minutes; The resin composition according to claim 1, comprising, in this order:

3. The resin composition according to claim 1 , further comprising (C) an inorganic filler.

4. The resin composition according to claim 3, wherein the amount of the inorganic filler (C) is 70% by mass or more relative to 100% by mass of the nonvolatile components of the resin composition.

5. 2. The resin composition according to claim 1, wherein the ratio M(B) / M(A) of the number of active groups of the curing agent (B) to the number of epoxy groups of the epoxy resin (A) is 1.6 or more.

6. A resin sheet comprising a support and a resin composition layer formed on the support; The resin sheet, wherein the resin composition layer comprises the resin composition according to any one of claims 1 to 5.

7. The method for producing a resin sheet according to claim 6, A step of preparing a resin varnish containing (A) an epoxy resin, (B) a curing agent, and (G) a solvent; A step of applying a resin varnish onto a support; and a step of drying the applied resin varnish to form a resin composition layer; A method for manufacturing a resin sheet, comprising the steps of:

8. The method for producing a resin sheet according to claim 7, wherein the resin varnish is dried at a drying temperature of 40°C or higher and 150°C or lower for a drying time of 60 seconds or higher and 10 minutes or shorter.

9. A circuit board comprising a cured product of the resin composition according to any one of claims 1 to 5.

10. a step of laminating an inner layer substrate and the resin sheet according to claim 6 so that the inner layer substrate and the resin composition layer are bonded to each other; and curing the resin composition layer; A method for manufacturing a circuit board, wherein the step of laminating an inner layer substrate and a resin sheet includes allowing a portion of a resin composition layer to seep out from a gap between the inner layer substrate and the support.

11. A semiconductor device comprising the circuit board according to claim 9.

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