Resin composition

Abstract

The present invention provides: a resin composition which enables the achievement of a cured product that has a low dielectric loss tangent, is capable of suppressing warpage after curing, and is excellent in terms of reflow resistance; a cured product of the resin composition; a resin sheet which contains the resin composition; a circuit board which comprises a cured product of the resin composition; and a semiconductor device which comprises the circuit board. This resin composition contains: (A) a compound that has a radically polymerizable group at an end, has a weight average molecular weight (Mw) of more than 5,000 but not more than 300,000, and a tensile elastic modulus of 1 GPa or less as measured at 25°C in accordance with JIS K7161; (B) an inorganic filler; and (C) a compound that has a radically polymerizable group and has a weight average molecular weight (Mw) of 5,000 or less.

Description

resin composition

[0001] The present invention relates to a resin composition, and further to a cured product of the resin composition, a resin sheet, a circuit board, and a semiconductor device.

[0002] For next-generation high-speed communications, there is an increasing need for low dielectric loss tangents in insulating materials such as encapsulants for semiconductor chip packages and interlayer insulating materials for circuit boards.Furthermore, with the need for larger substrates, such as wafer-level packaging (WLP) and panel-level packaging (PLP), it is becoming increasingly important to reduce warpage in the overall package structure.

[0003] Conventionally, by incorporating a high content of inorganic fillers or a stress relaxation agent, excellent dielectric properties have been ensured, while low warpage has been achieved through low thermal expansion and stress relaxation capabilities (for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2018-168217

[0005] On the other hand, as the need for larger sizes increases, the demand for even lower warpage requires the addition of more stress relaxation agents, but this is known to be a trade-off with a low dielectric loss tangent.In addition, in cured products that exhibit a low dielectric loss tangent, swelling can occur between the cured product and the wiring (conductor layer) when subjected to reflow, resulting in reduced reliability.

[0006] The present invention has been made in view of the above, and has an object to provide a resin composition that provides a cured product that has a low dielectric tangent, is capable of suppressing warping after curing, and has excellent reflow resistance; a cured product of the resin composition; a resin sheet containing the resin composition; a circuit board that includes a cured product of the resin composition; and a semiconductor device that includes the circuit board.

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, the present inventors have found that the above-mentioned problems can be solved by using a resin composition containing: (A) a compound having a terminal radical polymerizable group, a weight average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161; (B) an inorganic filler; and (C) a compound having a radical polymerizable group and a weight average molecular weight (Mw) of 5,000 or less, and have thus completed the present invention. That is, the present invention includes the following.

[0008] <1> A resin composition comprising: (A) a compound having a terminal radically polymerizable group, a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity measured at 25°C in accordance with JIS K7161 of 1 GPa or less; (B) an inorganic filler; and (C) a compound having a radically polymerizable group and a weight-average molecular weight (Mw) of 5,000 or less. <2> The resin composition according to <1>, in which the component (A) contains an imide skeleton. <3> The resin composition according to <1> or <2>, in which the component (A) contains an imide skeleton in its main chain. <4> The resin composition according to any one of <1> to <3>, in which the component (A) contains a structure represented by the following formula (A-1): (In formula (A-1), R Ａ１ represents a tetravalent group obtained by removing an acid anhydride group from a tetracarboxylic dianhydride; and * represents a bond.) <5> The resin composition according to <4>, wherein the component (A) contains a structure represented by formula (A-1) in combination with a structure represented by formula (A-3): (In formula (A-3), R Ａ３represents a divalent group obtained by removing two hydroxyl groups from a polyol compound having two or more hydroxyl groups per molecule; * represents a bond.) <6> The resin composition according to any one of <1> to <5>, wherein the content of component (B) is 50% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition. <7> The resin composition according to any one of <1> to <6>, wherein component (A) includes one or more structural units selected from the group consisting of polyolefin structural units, polycarbonate structural units, polyether structural units, polyester structural units, poly(meth)acrylic structural units, and polysiloxane structural units. <8> The resin composition according to any one of <1> to <7>, wherein component (A) includes a polyolefin structural unit. <9> The resin composition according to any one of <1> to <8>, wherein component (C) includes a maleimide-based radically polymerizable compound. <10> The resin composition according to any one of <1> to <9>, wherein the content of the (A) component is 0.1% by mass or more and 30% by mass or less, relative to 100% by mass of the non-volatile components of the resin composition. <11> The resin composition according to any one of <1> to <10>, wherein the content of the (C) component is 5% by mass or more and 40% by mass or less, relative to 100% by mass of the non-volatile components of the resin composition. <12> The resin composition according to any one of <1> to <11>, wherein the mass ratio of the (A) component to the (C) component (content of the (A) component) / (content of the (C) component) is 0.01 or more and 1.5 or less. <13> The resin composition according to any one of <1> to <12>, further comprising (D) a polymerization initiator. <14> The resin composition according to any one of <1> to <13>, further comprising (E) a polymer resin. <15> The resin composition according to any one of <1> to <14>, which is used to form an insulating layer of a circuit board. <16> A cured product of the resin composition according to any one of <1> to <15>. <17> A resin sheet comprising a support and a resin composition layer formed on the support, wherein the resin composition layer comprises the resin composition according to any one of <1> to <15>. <18> A circuit board comprising a cured product of the resin composition according to any one of <1> to <15>. <19> A semiconductor device comprising the circuit board according to <18>.

[0009] <Explanation of Terms> In this specification, the term "non-volatile components" in relation to a resin composition refers to all components constituting the resin composition other than the solvent, which will be described later. Also, in this specification, the term "resin components" in relation to a resin composition refers to all non-volatile components constituting the resin composition excluding inorganic fillers.

[0010] According to the present invention, it is possible to provide a resin composition that provides a cured product with a low dielectric tangent, that can suppress warping after curing, and that has excellent reflow resistance; a cured product of the resin composition; a resin sheet containing the resin composition; a circuit board containing the cured product of the resin composition; and a semiconductor device that includes the circuit board.

[0011] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0012] [Resin Composition] The resin composition of the present invention is characterized by comprising: (A) a compound having a terminal radical polymerizable group, a weight average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less, measured at 25°C in accordance with JIS K7161; (B) an inorganic filler; and (C) a compound having a terminal radical polymerizable group and a weight average molecular weight (Mw) of 5,000 or less. In the following description, "(A) a compound having a terminal radical polymerizable group, a weight average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less, measured at 25°C in accordance with JIS K7161" may be referred to as "(A) a high-molecular-weight, low-elasticity compound having a terminal radical polymerizable group." Furthermore, "(C) a compound having a terminal radical polymerizable group and a weight average molecular weight (Mw) of 5,000 or less" may be referred to as "(C) a compound having a radical polymerizable group."

[0013] The resin composition of the present invention may further contain optional components in combination with components (A) to (C). Examples of optional components include (D) a polymerization initiator, (E) a polymer resin, (F) optional additives, and (G) a solvent. Each component contained in the resin composition will be described in detail below.

[0014] <(A) High-Molecular-Weight, Low-Elasticity Compound Having a Terminal Radically Polymerizable Group (a compound having a terminal radically polymerizable group, a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161)> The resin composition of the present invention includes, as component (A), a high-molecular-weight, low-elasticity compound having a terminal radically polymerizable group. The weight-average molecular weight (Mw) of component (A) is more than 5,000 and not more than 300,000. Furthermore, the tensile modulus of elasticity of component (A) as measured at 25°C in accordance with JIS K7161 is 1 GPa or less. In the resin composition of the present invention, one type of component (A) may be used alone, or two or more types may be used in combination.

[0015] As described above, the weight-average molecular weight (Mw) of component (A) is more than 5,000 and not more than 300,000. The lower limit of the weight-average molecular weight (Mw) of component (A) is preferably 6,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more. The upper limit of the weight-average molecular weight is preferably 250,000 or less, more preferably 200,000 or less, even more preferably 150,000 or less, still more preferably 100,000 or less, 80,000 or less, 60,000 or less, 50,000 or less, or 40,000 or less. The weight-average molecular weight of the (A) high-molecular-weight, low-elasticity compound having a terminal radical polymerizable group can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0016] As described above, the tensile modulus of elasticity of component (A) measured at 25°C in accordance with JIS K7161 is 1 GPa or less. Such a tensile modulus is preferably 0.5 GPa or less, more preferably 0.1 GPa or less, and even more preferably 0.05 GPa or less. The lower limit of such a tensile modulus is not particularly limited and may be, for example, 0.01 MPa. The tensile modulus of component (A) can be measured by the method described in <Synthesis Example 1: Synthesis of Elastomer A1> below.

[0017] The component (A) has a radical polymerizable group at its terminal. Examples of the radical polymerizable group at the terminal of the component (A) include a vinyl group, an allyl group, a vinylphenyl group, a maleimide group, and a (meth)acryloyl group. When the component (A) contains two or more radical polymerizable groups, the two or more radical polymerizable groups may be the same or different. Among these, the radical polymerizable group at the terminal of the component (A) is preferably a (meth)acryloyl group, from the viewpoints that, in combination with the inorganic filler (B) and the compound having a radical polymerizable group (C), the dielectric tangent is lower, warping after curing can be further suppressed, a cured product with better reflow resistance can be obtained, and a resin composition layer with excellent appearance can be obtained.

[0018] In combination with (B) an inorganic filler and (C) a compound having a radical polymerizable group, the component (A) preferably contains an imide skeleton, from the viewpoint of providing a cured product with a lower dielectric tangent, greater suppression of warpage after curing, and superior reflow resistance. The imide skeleton refers to a skeleton containing an imide bond. The imide skeleton may be contained in the main chain of the component (A) or in a side chain of the component (A). Examples of embodiments in which the main chain of the component (A) contains an imide skeleton include an embodiment in which a maleimide group is contained at the end of the main chain, and an embodiment in which the main chain contains an imide skeleton. Among these, the component (A) preferably contains an imide skeleton in the main chain, and more preferably contains an imide skeleton in the main chain or both at the end and inside of the main chain.

[0019] In combination with (B) the inorganic filler and (C) the compound having a radical polymerizable group, from the viewpoint of providing a cured product having a lower dielectric tangent, being able to further suppress warpage after curing, and being more excellent in reflow resistance, as well as providing a resin composition layer having excellent appearance, it is preferable that the component (A) contains a structure represented by the following formula (A-1) as the imide skeleton:

[0020]

[0021] (In formula (A-1), R Ａ１ represents a tetravalent group obtained by removing an acid anhydride group from a tetracarboxylic dianhydride; * represents a bond.

[0022] In formula (A-1), R Ａ１ represents a tetravalent group obtained by removing the acid anhydride group from a tetracarboxylic dianhydride. Ａ１ In the group represented by the formula (I), the tetracarboxylic acid dianhydride may be an aliphatic tetracarboxylic acid dianhydride, an aromatic tetracarboxylic acid dianhydride, or a combination of these. The tetracarboxylic acid dianhydride may be used alone or in combination of two or more. Ａ１The group represented by the formula (I) is preferably a tetravalent group obtained by removing the acid anhydride group from an aromatic tetracarboxylic dianhydride. Examples of aromatic tetracarboxylic dianhydrides include benzenetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, anthracenetetracarboxylic dianhydride, and diphthalic dianhydride. Examples of diphthalic dianhydrides include 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylethertetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, and 2,3,3',4'-biphenyltetracarboxylic dianhydride. carboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-diphenylethertetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl)sulfone dianhydride, 4,4'-oxydiphthalic anhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethynylidene-4 ,4'-diphthalic dianhydride, 2,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenyl)benzene dianhydride

[0039] Examples of the dianhydride include 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)bisphthalic dianhydride.

[0023] In a more preferred embodiment, R Ａ１The group represented by the formula (A-2-1) is preferably a tetravalent group represented by the formula (A-2-2) below.

[0024]

[0025] (In formula (A-2-1) and formula (A-2-2), R Ａ２ represents a single bond or a divalent linking group; n Ａ２ represents 0, 1 or 2; * represents a bond.

[0026] In formula (A-2-1), n Ａ２ represents 0, 1 or 2. Ａ２ is preferably 0 or 1.

[0027] In formula (A-2-2), R Ａ２ represents a single bond or a divalent linking group. Ａ２ Examples of the divalent linking group represented by the formula (I) include a divalent group consisting of one or more (for example, 1 to 3000, 1 to 1000, 1 to 100, or 1 to 50) skeletal atoms selected from carbon atoms, oxygen atoms, nitrogen atoms, and sulfur atoms. Examples of the divalent linking group include an alkylene group, an alkenylene group, an arylene group, a heteroarylene group, -O-, -C(=O)-, -C(=O)-O-, -N(R Ｘ ) - (where R Ｘ represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms.), —C(═O)—NH—, —N(R Ｘ )-C(=O)-N(R Ｘ )-, -S-, -S(=O)-, -S(O) ２ -, etc., and groups formed by combining a plurality of these groups may also be used. Ａ２ is a single bond, —O—, —C(═O)—, or —C(═O)—O—CH ２ -CH ２ It is preferably —O—C(═O)—.

[0028] In combination with (B) the inorganic filler and (C) the compound having a radical polymerizable group, from the viewpoint of providing a cured product having a lower dielectric tangent, being able to further suppress warpage after curing, and having better reflow resistance, it is preferable that the component (A) contains one or more structural units selected from the group consisting of a polyolefin structural unit, a polycarbonate structural unit, a polyether structural unit, a polyester structural unit, a poly(meth)acrylic structural unit, and a polysiloxane structural unit.

[0029] Examples of polyolefin structural units include polyethylene structural units, polypropylene structural units, polybutadiene structural units, hydrogenated polybutadiene structural units, polyisopropylene structural units, hydrogenated polyisopropylene structural units, etc. Here, the term "hydrogenated polybutadiene structural units" refers to polybutadiene structural units in which some or all of the unsaturated bonds have been hydrogenated, and similarly, the term "hydrogenated polyisoprene structural units" refers to polyisoprene structural units in which some or all of the unsaturated bonds have been hydrogenated.

[0030] For example, when component (A) is produced using a polyolefin structure-containing polyol compound, the polyolefin structural unit may be the remaining structural unit obtained by removing two or more hydroxyl groups from the polyolefin structure-containing polyol compound. Commercially available polyolefin structure-containing polyol compounds may be used, and examples of such commercially available products include "G-1000," "G-2000," and "G-3000" (polybutadiene having hydroxy groups at both ends), and "GI-1000," "GI-2000," and "GI-3000" (polybutadiene having hydroxy groups at both ends, hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd.

[0031] Examples of polycarbonate structural units include aliphatic polycarbonates (polyethylene carbonate, polypropylene carbonate, polybutylene carbonate, polycyclohexane carbonate, etc.) and aromatic polycarbonates (polybisphenol A carbonate, polybisphenol F carbonate, polybisphenol S carbonate, etc.).

[0032] For example, when component (A) is produced using a polycarbonate structure-containing polyol compound, the polycarbonate structural unit may be the remaining structural unit obtained by removing two or more hydroxyl groups from the polycarbonate structure-containing polyol compound. Commercially available polycarbonate structure-containing polyol compounds may be used, and examples of such commercially available products include "T6002" and "T6001" (polycarbonates with hydroxy groups at both ends) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2015N," "C-2090," and "C-3090" (polycarbonates with hydroxy groups at both ends) manufactured by Kuraray Co., Ltd.

[0033] Examples of the polyether structural unit include a polyethylene glycol structural unit, a polypropylene glycol structural unit, a polytetramethylene glycol structural unit, and a polybutylene glycol structural unit.

[0034] For example, when component (A) is produced using a polyether structure-containing polyol compound, the polyether structural unit may be the remaining structural unit obtained by removing two or more hydroxyl groups from the polyether structure-containing polyol compound. Commercially available polyether structure-containing polyol compounds may be used, and examples of such commercially available products include NOF Corporation's "Pronon #102", "Pronon #104", "Pronon #201", "Pronon #202B", "Pronon #204", "Pronon #208", "Unilube 70DP-600B", and "Unilube 70DP-950B" (polyethylene glycol-polypropylene glycol copolymers), and ADEKA Corporation's "Pluronic (registered trademark) L-23", "Pluronic (registered trademark) L-31", "Pluronic (registered trademark) L-44", "Pluronic (registered trademark) L-61", "ADEKA Pluronic (registered trademark) L-62", "Pluronic (registered trademark) L-64", and "Pluronic (registered trademark) L-71," "Pluronic® L-72," "Pluronic® L-101," "Pluronic® L-121," "Pluronic® P-84," "Pluronic® P-85," "Pluronic® P-103," "Pluronic® F-68," "Pluronic® F-88," "Pluronic® F-108," "Pluronic® 25R-1," "Pluronic® 25R-2," "Pluronic® 17R-2," "Pluronic® 17R-3," and "Pluronic® 17R-4" (polyethylene glycol-polypropylene glycol copolymers).

[0035] Examples of polyester structural units include polyethylene terephthalate structural units, polybutylene terephthalate structural units, polyethylene naphthalate structural units, polybutylene naphthalate structural units, and polytrimethylene terephthalate structural units.

[0036] For example, when component (A) is produced using a polyester structure-containing polyol compound, the polyester structural unit may be the remaining structural unit obtained by removing two or more hydroxyl groups from the polyester structure-containing polyol compound. The polyester structure-containing polyol compound may be a commercially available product, such as Vylon (registered trademark) manufactured by Toyobo Co., Ltd., Polyester (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., or Slack (registered trademark) manufactured by Hitachi Chemical Polymer Co., Ltd.

[0037] The poly(meth)acrylic structural unit refers to a structural unit containing a plurality of at least one of an acrylic structure and a methacrylic structure. For example, when component (A) is produced using a poly(meth)acrylic structure-containing polyol compound, the poly(meth)acrylic structural unit may be the remaining structural unit obtained by removing two or more hydroxyl groups from the poly(meth)acrylic structure-containing polyol compound. The poly(meth)acrylic structure-containing polyol compound may be a commercially available product, and examples of such commercially available products include Teisan Resin "SG-600TEA" and "SG-790" (hydroxy group-containing acrylic ester copolymer resin) manufactured by Nagase ChemteX Corporation, and "W-197C" (hydroxy group-containing acrylic ester copolymer resin) manufactured by Negami Chemical Industrial Co., Ltd.

[0038] Examples of the polysiloxane structural unit include a dialkylpolysiloxane structural unit, a diarylpolysiloxane structural unit, a monoalkylmonoarylpolysiloxane structural unit, and a monoalkylpolysiloxane structural unit.

[0039] For example, when component (A) is produced using a polysiloxane structure-containing polyol compound, the polysiloxane structural unit may be the structural unit remaining after removing two or more hydroxyl groups from the polysiloxane structure-containing polyol compound. The polysiloxane structure-containing polyol compound may be a commercially available product, such as "X-21-5841" or "KF-9701" (polysiloxanes terminated with hydroxy groups) manufactured by Shin-Etsu Chemical Co., Ltd.

[0040] In combination with (B) the inorganic filler and (C) the compound having a radical polymerizable group, from the viewpoint of providing a cured product having a lower dielectric tangent, being able to further suppress warpage after curing, and being more excellent in reflow resistance, as well as providing a resin composition layer having excellent appearance, it is preferable that the component (A) contains a structure represented by the following formula (A-3), and it is preferable that the component (A) contains a combination of the structure represented by the above formula (A-1) and the structure represented by the following formula (A-3).

[0041]

[0042] (In formula (A-3), R Ａ３ represents a divalent group obtained by removing two hydroxyl groups from a polyol compound having two or more hydroxyl groups in one molecule; * represents a bond.

[0043] In formula (A-3), R Ａ３ R represents a divalent group obtained by removing two hydroxyl groups from a polyol compound having two or more alcoholic hydroxyl groups in one molecule. Ａ３ In the group represented by the formula (I), the polyol compound preferably contains one or more structural units selected from the group consisting of polyolefin structural units, polycarbonate structural units, polyether structural units, polyester structural units, poly(meth)acrylic structural units, and polysiloxane structural units, more preferably contains one or more structural units selected from the group consisting of polyolefin structural units, polycarbonate structural units, polyether structural units, polyester structural units, and polysiloxane structural units, even more preferably contains one or more structural units selected from the group consisting of polyolefin structural units, polycarbonate structural units, and polysiloxane structural units, and even more preferably contains a polyolefin structural unit. The polyol compound may be used alone or in combination of two or more. The polyolefin structural units, polycarbonate structural units, polyether structural units, polyester structural units, poly(meth)acrylic structural units, and polysiloxane structural units are as described above.

[0044] In a preferred embodiment, the structure represented by formula (A-3) can be obtained by polycondensation of a polyol compound having two or more hydroxyl groups per molecule with a polyisocyanate compound. Examples of the polyisocyanate include aliphatic diisocyanate compounds such as butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; phenylene diisocyanates such as p-phenylene diisocyanate and m-phenylene diisocyanate; xylylene diisocyanates such as p-xylene diisocyanate and m-xylene diisocyanate; toluene-2,4-diisocyanate; and toluene-2,4-diisocyanate. Examples of the diisocyanate include aromatic diisocyanate compounds such as toluene diisocyanate such as benzene-2,6-diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'-diethyldiphenyl-4,4'-diisocyanate, m-xylene diisocyanate, 1,3-bis(α,α-dimethylisocyanatomethyl)benzene, tetramethylxylylene diisocyanate, diphenylene ether-4,4'-diisocyanate, and naphthalene diisocyanate; polymethylene polyphenyl polyisocyanate having a repeating structure represented by the following formula (A-4); and isocyanurate-modified, biuret-modified, and allophanate-modified polyisocyanates thereof. The polyisocyanate compounds may be used alone or in combination of two or more.

[0045]

[0046] (In formula (A-4), R Ａ４１ each independently represents an alkyl group having 1 to 4 carbon atoms; R Ａ４２ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms; n Ａ４１ represents 0 or an integer of 1 to 3; n Ａ４２ represents an integer of 1 to 15; * represents a bond.

[0047] Among these, as the polyisocyanate compound capable of providing the structure represented by formula (A-3), an alicyclic diisocyanate compound is preferred, and isophorone diisocyanate is more preferred.

[0048] In combination with (B) the inorganic filler and (C) the compound having a radical polymerizable group, the component (A) preferably has a structure represented by the following formula (A-5), from the viewpoint of providing a cured product having a lower dielectric tangent, being able to further suppress warpage after curing, and being more excellent in reflow resistance, as well as providing a resin composition layer having excellent appearance.

[0049]

[0050] (In formula (A-5), n Ａ５ represents an integer of 4 to 90; * represents a bond.

[0051] There is no limitation on the method for producing the high-molecular-weight, low-elasticity compound (A) having a radical polymerizable group at its terminal. In addition, the high-molecular-weight, low-elasticity compound (A) having a radical polymerizable group at its terminal may be purchased from the market.

[0052] The content of component (A) in the resin composition 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 total of components (A) to (C). When the content of component (A) is within the above range, the cured product of the resin composition exhibits a low dielectric tangent, excellent reflow resistance, and particularly suppresses warpage after curing.

[0053] When the resin composition contains components other than components (A) to (C), the content of component (A) in the resin composition 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 non-volatile components of the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. When the content of component (A) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0054] When the resin composition contains components other than components (A) to (C), the content of component (A) in the resin composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more or 7% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less, relative to 100% by mass of the resin components of the resin composition. When the content of component (A) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0055] <(B) Inorganic Filler> The resin composition of the present invention contains an inorganic filler (B) as the component (B). The inorganic filler (B) does not include those corresponding to the above-mentioned component (A). The inorganic filler (B) is contained in the resin composition in the form of particles, and is contained in the cured product while maintaining this particulate form. In the resin composition of the present invention, the component (B) may be used alone or in combination of two or more.

[0056] (B) Inorganic filler materials can be inorganic compounds. (B) Inorganic filler materials include, for example, 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, one or more materials selected from the group consisting of silica and alumina are preferred, and silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Furthermore, spherical silica is preferred.

[0057] (B) 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 Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Hipressica FH" manufactured by Ube Exsymo Co., Ltd.

[0058] The average particle size of the (B) inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, 2 μm or less, 1 μm or less, or 0.7 μm or less. The lower limit of the average particle size is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.07 μm or more, 0.1 μm or more, or 0.2 μm or more. The average particle size of the (B) inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler is created on a volume basis 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 it ultrasonically for 10 minutes. The measurement sample was measured using a laser diffraction particle size distribution analyzer, with blue and red light source wavelengths used and a flow cell system to measure the volumetric particle size distribution of the inorganic filler, and the average particle size was calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction particle size distribution analyzer is the "LA-960" manufactured by Horiba, Ltd.

[0059] The specific surface area of ​​the inorganic filler (B) is not particularly limited, but is preferably 0.1 m ２ / g or more, more preferably 0.5m ２ / g or more, more preferably 1m ２ / g or more, 3m ２ / g or more or 5m ２ The upper limit of the specific surface area is not particularly limited, but is preferably 100 m ２ / g or less, more preferably 80m ２ / g or less, more preferably 60m ２ / g or less, 50m ２ / g or less or 40m ２ The specific surface area of ​​component (D) is determined 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.

[0060] The inorganic filler (B) is preferably surface-treated with an appropriate surface treatment agent. By performing the surface treatment, the moisture resistance and dispersibility of the inorganic filler (B) can be improved. Examples of the surface treatment agent include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, styryl silane coupling agents, (meth)acrylic silane coupling agents, amino silane coupling agents, isocyanurate silane coupling agents, ureido silane coupling agents, mercapto silane coupling agents, isocyanate silane coupling agents, and acid anhydride silane coupling agents; non-silane coupling alkoxysilane compounds such as methyltrimethoxysilane and phenyltrimethoxysilane; and silazane compounds. The surface treatment agents may be used alone or in combination of two or more.

[0061] Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0062] The degree of surface treatment with the surface treatment agent is preferably within a predetermined 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% by mass to 5% by mass of the surface treatment agent.

[0063] 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 0.02 mg / m ２ More than 0.1 mg / m ２ More preferably, 0.2 mg / m or more ２On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition or the melt viscosity in the form of a sheet, the upper limit of the carbon amount per unit surface area of ​​the inorganic filler (B) is 1 mg / m ２ Preferably, 0.8 mg / m or less ２ More preferably, 0.5 mg / m or less ２ The following is more preferable. (B) The carbon amount 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 carbon amount per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, an "EMIA-320V" manufactured by Horiba, Ltd. or the like can be used.

[0064] The content of component (B) in the resin composition is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, relative to 100% by mass of the total of components (A), (B), and (C), and is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 83% by mass or less or 82% by mass or less. When the content of component (B) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warpage after curing.

[0065] When the resin composition contains components other than components (A) to (C), the content of component (B) in the resin composition is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition, and is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 83% by mass or less or 82% by mass or less. When the content of component (B) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0066] <(C) Compound Having a Radically Polymerizable Group (Compound Having a Radical Polymerizable Group and Having a Weight Average Molecular Weight (Mw) of 5,000 or Less)> The resin composition of the present invention contains (C) a compound having a radically polymerizable group as the component (C). Unless otherwise specified, the (C) compound having a radically polymerizable group does not include compounds that fall under the above-mentioned components (A) and (B). In other words, the weight average molecular weight (Mw) of the component (C) is 5,000 or less. In the resin composition of the present invention, the component (C) may be used alone or in combination of two or more.

[0067] The weight-average molecular weight (Mw) of the compound having a radical polymerizable group (C) is 5,000 or less, preferably 4,000 or less, and more preferably 3,000 or less. The lower limit is not particularly limited, but may be, for example, 150 or more. The weight-average molecular weight of the compound having a radical polymerizable group (C) can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0068] The type of component (C) is not particularly limited as long as it has one or more (preferably two or more) radical polymerizable groups in one molecule. Examples of component (C) include compounds having one or more radical polymerizable groups selected from vinyl groups, allyl groups, vinylphenyl groups, (meth)acryloyl groups, and maleimide groups. When component (C) contains two or more radical polymerizable groups, these two or more radical polymerizable groups may be the same or different.

[0069] The compound (C) having a radical polymerizable group preferably includes one or more compounds selected from the group consisting of maleimide-based radical polymerizable compounds, (meth)acrylic-based radical polymerizable compounds, styrene-based radical polymerizable compounds, and allyl-based radical polymerizable compounds, and more preferably includes a maleimide-based radical polymerizable compound.

[0070] The maleimide radical polymerizable compound is, for example, a compound having one or more, preferably two or more, maleimide groups. The maleimide radical polymerizable compound may be an aliphatic maleimide compound containing an aliphatic amine skeleton, or an aromatic maleimide compound containing an aromatic amine skeleton. Commercially available maleimide radical polymerizable compounds include, for example, "SLK-2600" and "SLK-6895-T90" manufactured by Shin-Etsu Chemical Co., Ltd., "BMI-1500", "BMI-1700", "BMI-3000J", "BMI-689", and "BMI-2500" (dimer diamine structure-containing maleimide compounds) manufactured by Designer Molecules Inc., and "BMI-3000J", "BMI-689", and "BMI-2500" (dimer diamine structure-containing maleimide compounds) manufactured by Designer Molecules Inc. Examples of the maleimide-based radical polymerizable compound include "BMI-6100" manufactured by Nippon Kayaku Co., Ltd. (aromatic maleimide compound); "MIR-5000-60T" and "MIR-3000-70MT" (biphenylaralkyl maleimide compounds) manufactured by Nippon Kayaku Co., Ltd.; "BMI-70" and "BMI-80" manufactured by K.I. Kasei Co., Ltd.; and "BMI-2300" and "BMI-TMH" manufactured by Daiwa Kasei Kogyo Co., Ltd. Furthermore, as the maleimide-based radical polymerizable compound, a maleimide resin (indane ring skeleton-containing maleimide compound) disclosed in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211 may also be used.

[0071] The (meth)acrylic radically polymerizable compound is, for example, a compound having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups. Examples of the (meth)acrylic radical polymerizable compound include aliphatic (meth)acrylic acid ester compounds such as cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxane dimethanol di(meth)acrylate, and the like. ether-containing (meth)acrylic acid ester compounds such as sa-1,8-octanediol di(meth)acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, and propoxylated bisphenol A di(meth)acrylate; isocyanurate-containing (meth)acrylic acid ester compounds such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; and acrylic acid ester compounds such as (meth)acrylic-modified polyphenylene ether resins.Examples of commercially available (meth)acrylic radically polymerizable compounds include "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate) and "DCP" (tricyclodecane dimethanol dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic-modified polyphenylene ether) manufactured by SABIC Corporation.

[0072] The styrene-based radical polymerizable compound is, for example, a compound having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom. Examples of the styrene-based radical polymerizable compound include divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, bis(4-vinylphenyl)ether, vinylbenzyl-modified polyphenylene ether resin, and styrene-divinylbenzene copolymer. Examples of commercially available styrene-based radically polymerizable compounds include "ODV-XET (X03)", "ODV-XET (X04)", and "ODV-XET (X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "OPE-2St", "OPE-2St 1200", and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0073] The allyl radical polymerizable compound is, for example, a compound having one or more, preferably two or more, allyl groups. Examples of the allyl radical polymerizable compound include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenecarboxylate; isocyanuric acid allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; allyl silane compounds such as diallyl diphenyl silane; and resins containing a plurality of benzene rings and allyl groups. Commercially available allyl radical polymerizable compounds include "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Industry Co., Ltd.; "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; "DAND" (2,3-diallyl naphthalenecarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd.; "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Chemicals Corporation; and "NE-V-1100-70T" (a resin containing a plurality of benzene rings and a plurality of allyl groups) manufactured by DIC Corporation.

[0074] The radical polymerizable group equivalent of the compound (C) having a radical polymerizable group is preferably 20 g / eq. to 3,000 g / eq., more preferably 50 g / eq. to 2,500 g / eq., even more preferably 70 g / eq. to 2,000 g / eq., and still more preferably 90 g / eq. to 1,500 g / eq. The radical polymerizable group equivalent represents the mass of the compound (C) having a radical polymerizable group per equivalent of the radical polymerizable group.

[0075] The content of component (C) in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, relative to 100% by mass of the total of components (A) to (C). It is also preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less or 27% by mass or less. When the content of component (C) is within the above range, the cured product of the resin composition exhibits a low dielectric tangent, excellent reflow resistance, and particularly suppresses warpage after curing.

[0076] When the resin composition contains components other than components (A) to (C), the content of component (C) in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less or 27% by mass or less. When the content of component (C) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0077] When the resin composition contains components other than components (A) to (C), the content of component (C) in the resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, relative to 100% by mass of the resin components of the resin composition, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 91% by mass or less. When the content of component (C) is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0078] The ratio of the content of component (A) to the content of component (C) in the resin composition, i.e., the mass ratio of component (A) to component (C), (content of component (A)) / (content of component (C)), is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.09 or more, and is preferably 1.5 or less, more preferably 1 or less, and even more preferably 0.85 or less. When such a mass ratio is within the above range, the cured product of the resin composition has a low dielectric tangent, exhibits excellent reflow resistance, and is particularly able to suppress warping after curing.

[0079] <(D) Polymerization Initiator> The resin composition of the present invention may contain a (D) polymerization initiator as an optional component. Unless otherwise specified, the (D) polymerization initiator as the (D) component does not include those corresponding to the above-mentioned components (A) to (C). The (D) polymerization initiator can promote the reaction between (A) the high-molecular-weight, low-elasticity compound having a terminal radical polymerizable group and (C) the compound having a radical polymerizable group, thereby promoting the curing of the resin composition. When the resin composition contains a (D) polymerization initiator, one type of (D) component may be used alone, or two or more types may be used in combination.

[0080] As the polymerization initiator (D), for example, a compound capable of generating free radicals upon heating is used. Examples of the polymerization initiator (D) include peroxide-based radical polymerization initiators and azo-based radical polymerization initiators, and among these, peroxide-based radical polymerization initiators are preferred.

[0081] Examples of the peroxide radical polymerization initiator include hydroperoxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxide compounds such as tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and diacyl peroxide compounds such as dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, and bis(4-tert-butylcyclohexyl)peroxydicarbonate. peroxyester compounds such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyneodecanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butyl peroxylaurate, (1,1-dimethylpropyl) 2-ethylperhexanoate, tert-butyl 2-ethylperhexanoate, tert-butyl 3,5,5-trimethylperhexanoate, tert-butylperoxy-2-ethylhexyl monocarbonate, and tert-butylperoxymaleic acid; and the like.

[0082] Examples of the azo radical polymerization initiator include azonitrile compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl)azo]formamide, and 2-phenylazo-4-methoxy-2,4-dimethyl-valeronitrile; 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], and 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide]. azoamide compounds such as 2,2'-azobis[2-methyl-N-[2-(1-hydroxybutyl)]-propionamide], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(2-methylpropionamide) dihydrate, 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); alkyl azo compounds such as 2,2'-azobis(2,4,4-trimethylpentane) and 2,2'-azobis(2-methylpropane); and the like.

[0083] Examples of commercially available products of the polymerization initiator (D) include "Perbutyl C," "Perbutyl A," "Perbutyl P," "Perbutyl L," "Perbutyl O," "Perbutyl ND," "Perbutyl Z," "Perbutyl I," "Percumyl P," "Percumyl D," "Perhexyl D," "Perhexyl A," "Perhexyl I," "Perhexyl Z," "Perhexyl ND," "Perhexyl O," and "Perhexyl PV," all manufactured by NOF Corporation; and "Luperox DTA" manufactured by Arkema Yoshitomi Co., Ltd.

[0084] When the resin composition contains a polymerization initiator (D), the content of the component (D) in the resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition, and is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less.

[0085] When the resin composition contains a polymerization initiator (D), the content of the component (D) in the resin composition is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, relative to 100% by mass of the resin components of the resin composition, and is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less.

[0086] <(E) Polymer Resin> The resin composition of the present invention may contain a (E) polymer resin as an optional component. Unless otherwise specified, the (E) polymer resin as the (E) component does not include those corresponding to the above-mentioned components (A) to (D). The (E) polymer resin may be included in the resin composition in a state where it is compatible with resin components other than the (E) polymer resin. When the resin composition contains the (E) component, the (E) component may be used alone or in a combination of two or more types.

[0087] The weight average molecular weight (Mw) of the (E) polymer resin is, for example, greater than 5,000, preferably at least 8,000, more preferably at least 10,000, even more preferably at least 20,000, and is preferably at most 100,000, more preferably at most 70,000, even more preferably at most 60,000. The weight average molecular weight of the (E) polymer resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0088] Examples of (E) polymer resins include oxazoline group-containing resins, phenoxy resins, polybutadiene resins, polyimide resins, polyvinyl acetal resins, polyolefin resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. As mentioned above, the (E) polymer resin does not include components (A) to (D). Therefore, compounds having a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161, and having a radically polymerizable group at its terminal, are classified as component (A) rather than component (E).

[0089] The oxazoline group-containing resin can be obtained by polymerizing an addition-polymerizable oxazoline compound (vinyloxazoline skeleton-containing monomer) such as, for example, 2-isopropenyl-2-oxazoline, 5-methyl-2-isopropenyl-2-oxazoline, 4,4-dimethyl-2-isopropenyl-2-oxazoline, 4-methyl-2-isopropenyl-2-oxazoline, 4,4,5-trimethyl-2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, 5-methyl-2-vinyl-2-oxazoline, 4,4-dimethyl-2-vinyl-2-oxazoline, 4-methyl-2-vinyl-2-oxazoline, or 4,4,5-trimethyl-2-vinyl-2-oxazoline. Furthermore, the oxazoline group-containing resin may be copolymerized with any monomer, such as a styrene-based monomer such as styrene, α-methylstyrene, 4-methylstyrene, 3-methylstyrene, 2-methylstyrene, 4-ethylstyrene, 4-tert-butylstyrene, p-divinylbenzene, m-divinylbenzene, etc. A specific example of the oxazoline group-containing resin is "PX-3-RP-61" manufactured by Nippon Shokubai Co., Ltd.

[0090] Examples of the phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" (phenoxy resin containing a bisphenol S skeleton) manufactured by Mitsubishi Chemical Corporation; "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX7200B35," "YL7500BH30," "YX6954BH30," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0091] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, and polyphenylene ether-polybutadiene resins. The polybutadiene resins used as component (E) do not include those corresponding to component (A). Polybutadiene resins whose molecular ends are blocked with phenolic resins may also be used.

[0092] As the polyimide resin, a resin having an imide structure (preferably a cyclic imide structure) can be used, and examples thereof include imidized products of acid anhydrides and diamine compounds; imidized products of acid anhydrides and diisocyanate compounds; etc. Note that the polyimide resin as component (E) does not include those corresponding to component (A). Among them, the polyimide resin as component (E) is preferably an imidized product of acid anhydrides and diamine compounds. Furthermore, the polyimide resin may contain an indane skeleton such as a trimethylindane skeleton, and for example, the indane skeleton may be contained in a structural unit formed by polymerization of a diamine compound.

[0093] As the acid anhydride for producing the polyimide resin, a tetracarboxylic acid anhydride is preferred. Examples of the tetracarboxylic acid anhydride include aromatic tetracarboxylic acid dianhydrides and aliphatic tetracarboxylic acid dianhydrides, with aromatic tetracarboxylic acid dianhydrides being preferred. Examples of the aromatic tetracarboxylic acid dianhydride include benzenetetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride, anthracenetetracarboxylic acid dianhydride, and diphthalic acid dianhydride, with diphthalic acid dianhydride being preferred. Examples of the diphthalic acid dianhydride include 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride. carboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-diphenylethertetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl)sulfone dianhydride, 4,4'-oxydiphthalic anhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethynylidene-4 ,4'-diphthalic dianhydride, 2,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenyl)benzene dianhydride

[0039] Examples of the dianhydride include 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)bisphthalic dianhydride.

[0094] Examples of diamine compounds for producing polyimide resins include aliphatic diamine compounds and aromatic diamine compounds, with aromatic diamine compounds being preferred. Examples of the dianiline compound include 4,4'-diamino-2,2'-ditrifluoromethyl-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl 4-aminobenzoate, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis(4-aminophenyl)propane, 4,4'-(hexafluoroisopropylidene)dianiline, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane,

[0033] hexafluoropropane, α,α-bis[4-(4-aminophenoxy)phenyl]-1,3-diisopropylbenzene, α,α-bis[4-(4-aminophenoxy)phenyl]-1,4-diisopropylbenzene, 4,4'-(9-fluorenylidene)dianiline, 2,2-bis(3-methyl-4-aminophenyl)propane, 2,2-bis(3-methyl-4-aminophenyl)benzene, 4,4'-diamino-3,3'-dimethyl-1,1'-biphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 9,9'-bis(3-methyl-4-aminophenyl)fluorene, 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindane, and the like.

[0095] Commercially available examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Other examples of polyimide resins include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (disclosed in JP-A-2006-37083), and polysiloxane skeleton-containing polyimides (disclosed in JP-A-2002-12667 and JP-A-2000-319386, etc.).

[0096] The polymer resin (E) may contain an elastomer. The elastomer is a flexible resin, preferably a resin with rubber elasticity or a resin that exhibits rubber elasticity by polymerizing with another component. Examples of rubber elasticity include resins that exhibit an elastic modulus of 1 GPa or less when subjected to a tensile test in accordance with Japanese Industrial Standards (JIS K7161) at a temperature of 25°C and a humidity of 40% RH. The elastic modulus of the elastomer is specifically in the range of, for example, 1 GPa or less, preferably 0.9 GPa or less, more preferably 0.8 GPa or less, and even more preferably 0.7 GPa or less, and preferably 0.01 GPa or more, more preferably 0.03 GPa or more, even more preferably 0.05 GPa or more, and even more preferably 0.1 GPa or more.

[0097] The elastomer is preferably one or more types selected from resins having a glass transition temperature (Tg) of 25°C or less and resins that are liquid at 25°C or less. The glass transition temperature of a resin having a glass transition temperature (Tg) of 25°C or less is preferably 20°C or less, more preferably 15°C or less. The lower limit of the glass transition temperature is not particularly limited, but may be, for example, -15°C or higher. Furthermore, the resin that is liquid at 25°C is preferably a resin that is liquid at 20°C or less, more preferably a resin that is liquid at 15°C or less. The glass transition temperature can be measured by DSC (differential scanning calorimetry).

[0098] The (E) polymer resin may be included in the resin composition in a state where it is compatible with resin components other than the (E) polymer resin. Such a compatible (E) polymer resin may be included in the cured product in a state where it is compatible with resin components other than the (E) polymer resin. Furthermore, the (E) polymer resin may be included in the resin composition in a particulate state where it is not compatible with resin components other than the (E) polymer resin. Such particulate (E) polymer resin may be included in the cured product in a particulate state where it is not compatible with resin components other than the (E) polymer resin. Furthermore, a particulate (E) polymer resin that is compatible with resin components other than the (E) polymer resin may be used in combination with a particulate (E) polymer resin.

[0099] Examples of particulate polymer resins (E) include rubber particles, polyamide microparticles, silicone particles, and core-shell particles. Among these, rubber particles and core-shell particles are preferred, with core-shell particles being more preferred. Core-shell particles are particulate polymer resins comprising a core particle and one or more shell layers covering the core particle. Core-shell particles are preferably core-shell graft copolymer particles comprising a core particle containing a resin and a shell portion obtained by graft copolymerizing a copolymerizable monomer component with the resin contained in the core particle. Here, the term "core-shell" does not necessarily refer only to particles in which the core particle and the shell portion are clearly distinguishable, but also includes particles in which the boundary between the core particle and the shell portion is unclear. Furthermore, the core particle does not necessarily have to be completely covered with the shell portion.

[0100] Commercially available core-shell type graft copolymer particles include, for example, "CHT" manufactured by Samsung SDI; "B602" manufactured by Techno UMG; and "Paraloid EXL2602," "Paraloid EXL2603," "Paraloid EXL2655," "Paraloid EXL2311," "Paraloid EXL2313," "Paraloid EXL2315," "Paraloid KM330," and "Paraloid EXL2311" manufactured by Dow Chemical Japan. Examples of such a polymer include "Paraloid KM336P" and "Paraloid KCZ201" manufactured by Mitsubishi Rayon Co., Ltd.; "Metablen C-223A", "Metablen E-901", "Metablen S-2001", "Metablen W-450A", and "Metablen SRK-200" manufactured by Mitsubishi Rayon Co., Ltd.; and "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-400", "Kane Ace M-580", and "Kane Ace MR-01" manufactured by Kaneka Corporation.

[0101] When the resin composition contains a polymer resin (E), the content of the component (E) in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.9% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition, and is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1.5% by mass or less.

[0102] When the resin composition contains a polymer resin (E), the content of the component (E) in the resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, relative to 100% by mass of the resin components of the resin composition, and is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 4% by mass or less.

[0103] <(F) Optional Additives> The resin composition of the present invention may further contain an optional additive (F) as an optional component. The optional additive (F) as component (F) does not include those corresponding to the above-mentioned components (A) to (E). Examples of the optional additive (F) include 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-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion promoters such as triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters. Examples of additives include antioxidants such as hindered phenol antioxidants, fluorescent brighteners such as stilbene derivatives, surfactants such as fluorine-based surfactants and silicone-based surfactants, flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic 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 singly or in combination of two or more.

[0104] <(G) Solvent> The resin composition may further contain a (G) solvent as an optional volatile component in addition to the non-volatile components such as the above-described components (A) to (F). Examples of the (G) 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 the solvent (G) 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. The solvent (G) may be used singly or in combination of two or more.

[0105] The content of the (G) solvent in the resin composition may be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, relative to 100% by mass of all components of the resin composition. The content of the (G) solvent in the resin composition may also be 0% by mass.

[0106] From the viewpoint of further achieving the desired effects of the present invention, the resin composition contains little or no epoxy resin. The content of the epoxy resin in the resin composition is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, 0.1% by mass or less, or 0.05% by mass or less, relative to 100% by mass of the resin components of the resin composition. The lower limit of the epoxy resin content may be 0% by mass or may be greater than 0% by mass, but from the viewpoint of further achieving the desired effects of the present invention, the closer to 0% by mass it is, the more preferable, and 0% by mass is even more preferable.

[0107] In order to further achieve the desired effects of the present invention, the resin composition contains a small amount of at least one thermosetting resin selected from the group consisting of active ester resins, phenolic resins, cyanate ester resins, benzoxazine resins, carbodiimide resins, acid anhydride resins, amine resins, and thiol resins, or does not contain at least one thermosetting resin selected from such a group. Active ester resins, phenolic resins, cyanate ester resins, benzoxazine resins, carbodiimide resins, acid anhydride resins, amine resins, and thiol resins can react with epoxy resins to function as curing agents, so these thermosetting resins are sometimes collectively referred to as "epoxy resin curing agents." The content of the epoxy resin curing agent in the resin composition is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, 0.1% by mass or less, or 0.05% by mass or less, based on 100% by mass of the resin components of the resin composition. The lower limit of the content of the epoxy resin curing agent may be 0% by mass or may be greater than 0% by mass. However, from the viewpoint of further achieving the desired effects of the present invention, the closer to 0% by mass the content is, the more preferable, and 0% by mass is even more preferable.

[0108] [Method for Producing Resin Composition] The resin composition can be produced, for example, by mixing components that can be contained in the resin composition. Thus, the resin composition can be produced by a production method including a step of mixing (A) a high-molecular-weight, low-elasticity compound having a terminal radical polymerizable group, (B) an inorganic filler, and (C) a compound having a radical polymerizable group. This production method may also include a step of mixing optional components such as components (D) to (G). Components (A) to (G) may be mixed in part or all at the same time, or they may be mixed sequentially.

[0109] [Characteristics of Resin Composition] The resin composition of the present invention contains a combination of the components (A), (B), and (C) (and, as necessary, the components (D), (E), (F), and (G)), and therefore provides a cured product that has a low dielectric tangent, can suppress warpage after curing, and has excellent reflow resistance.

[0110] The cured product of the resin composition of the present invention is characterized by a low dielectric loss tangent. Therefore, the cured product provides an insulating layer with a low dielectric loss tangent. For example, when measured at 5.8 GHz and 23°C as described in the section <Test Example 1: Measurement of Dielectric Loss Tangent Df> below, the dielectric loss tangent of the cured product obtained by heat-curing the resin composition (layer) at 190°C for 90 minutes is preferably 0.0035 or less, more preferably 0.0032 or less, and even more preferably 0.003 or less. The lower limit of the dielectric loss tangent may be 0.0001 or more.

[0111] The cured product of the resin composition of the present invention can effectively suppress warpage after curing. For example, when the warpage after curing is measured as described in the section <Test Example 2: Warpage Measurement Test> below, the warpage of the cured product obtained by heating the resin composition (layer) at 100°C for 30 minutes and then at 200°C for 90 minutes is preferably less than 2,500, more preferably 2,200 or less, and even more preferably 2,000 or less. In the cured product of the resin composition (layer), the lower limit of the warpage after curing can be 100 or more, for example.

[0112] The cured product of the resin composition of the present invention can effectively suppress the occurrence of abnormalities such as swelling after reflow. Therefore, the resin composition of the present invention can provide an insulating layer with excellent reflow resistance. For example, a resin composition (layer) is thermally cured at 200°C for 90 minutes to form an insulating layer, on which a conductor layer is formed by laminating a metal foil, and five 100 mm x 50 mm test pieces are obtained. These test pieces are then subjected to a test in which they are subjected to a reflow apparatus 10 times that reproduces a solder reflow temperature with a peak temperature of 260°C (the reflow temperature profile conforms to IPC / JEDEC J-STD-020C). In this case, the number of test pieces that exhibit abnormalities such as swelling is preferably one or less, more preferably zero. A specific method for evaluating reflow resistance may be the method described below in <Test Example 3: Evaluation Test for Reflow Resistance>.

[0113] The resin composition of the present invention can provide a resin composition layer with excellent appearance. Therefore, when a resin composition layer is formed using the resin composition of the present invention, the occurrence of unevenness and repelling in the resin composition layer can be suppressed. For example, when a resin composition layer is formed by applying a resin composition layer, preferably, unevenness and repelling occur only in a portion of the resin composition layer, and more preferably, unevenness and repelling do not occur throughout the resin composition layer. The method for evaluating the appearance of the resin composition layer can be, for example, the method described in <Test Example 4: Evaluation of the Appearance of the Resin Composition Layer>.

[0114] [Uses of Resin Composition] As described above, the resin composition of the present invention can provide a cured product that has a low dielectric loss tangent, can suppress warping after curing, and has excellent reflow resistance. Therefore, the resin composition of the present invention can be suitably used as a resin composition for forming an insulating layer of a printed wiring board (resin composition for an insulating layer of a printed wiring board), and can be more suitably used as a resin composition for forming an interlayer insulating layer of a printed wiring board (resin composition for an interlayer insulating layer of a printed wiring board). The resin composition of the present invention can also be suitably used as a resin composition for forming an insulating layer of a rewiring board of a semiconductor package (resin composition for an insulating layer of a rewiring board). In the present invention, printed wiring boards and rewiring boards are collectively referred to as "circuit boards," and therefore the resin composition of the present invention can be suitably used for the insulating layer of a circuit board.

[0115] The resin composition of the present invention can be further used in a wide range of applications requiring a resin composition, such as sheet-like laminate materials such as resin sheets and prepregs, solder resists, underfill materials, die bonding materials, hole filling resins, sealing resins, and component embedding resins.

[0116] [Sheet-like Laminated Material (Resin Sheet, Prepreg)] The resin composition of the present invention can be used as it is, but may also be used in the form of a sheet-like laminated material containing the resin composition.

[0117] As the sheet-like laminate material, the following resin sheets and prepregs are preferred.

[0118] In one embodiment, the resin sheet includes a support and a layer of a resin composition (hereinafter simply referred to as a "resin composition layer") provided on the support, and is characterized in that the resin composition layer is formed from the resin composition of the present invention.

[0119] The thickness of the resin composition layer varies depending on the application, and may be appropriately determined depending on the application. For example, from the viewpoint of thinning printed wiring boards and semiconductor packages, the thickness of the resin composition layer is preferably 100 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 1 μm or more, 5 μm or more, etc.

[0120] Examples of the support include a thermoplastic resin film, a metal foil, and a release paper, and a thermoplastic resin film or a metal foil is preferred. Therefore, in a preferred embodiment, the support is a thermoplastic resin film or a metal foil.

[0121] When a thermoplastic resin film is used as the support, examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0122] 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, such as copper, or a foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0123] The surface of the support to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, or an antistatic treatment. Alternatively, the support may be a support with a release layer, which has a release layer on the surface to be bonded to 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 resins, polyolefin resins, urethane resins, and silicone resins. Commercially available release agents include alkyd resin-based release agents such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation. Commercially available release layer supports include PET films having a release layer primarily composed of an alkyd resin-based release agent, such as "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 Ltd.

[0124] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0125] When a metal foil is used as the support, a metal foil with a support substrate may be used, which is a thin metal foil with a peelable support substrate attached thereto. In one embodiment, the metal foil with a support substrate includes a support substrate, a release layer provided on the support substrate, and a metal foil provided on the release layer. When a metal foil with a support substrate is used as the support, the resin composition layer is provided on the metal foil.

[0126] In the metal foil with a supporting substrate, the material of the supporting substrate is not particularly limited, and examples thereof include copper foil, aluminum foil, stainless steel foil, titanium foil, copper alloy foil, etc. When copper foil is used as the supporting substrate, it may be electrolytic copper foil or rolled copper foil. Furthermore, the release layer is not particularly limited as long as it can release the metal foil from the supporting substrate, and examples thereof include an alloy layer of an element selected from the group consisting of Cr, Ni, Co, Fe, Mo, Ti, W, and P; an organic coating, etc.

[0127] In the metal foil with a supporting substrate, the material of the metal foil is preferably, for example, copper foil or copper alloy foil.

[0128] In the metal foil with a supporting substrate, the thickness of the supporting substrate is not particularly limited, but is preferably in the range of 10 μm to 150 μm, more preferably in the range of 10 μm to 100 μm. The thickness of the metal foil may be, for example, in the range of 0.1 μm to 10 μm.

[0129] In one embodiment, the resin sheet may further include an optional layer as needed. Examples of such optional layers include a protective film provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, adhesion of dust and the like to the surface of the resin composition layer and scratches can be suppressed.

[0130] The resin sheet can be produced, for example, by preparing a liquid resin composition as is or a resin varnish by dissolving the resin composition in an organic solvent, applying this onto a support using a die coater or the like, and then drying to form a resin composition layer.

[0131] The organic solvent may be the same as the organic solvent described as a component of the resin composition. The organic solvent may be used alone or in combination of two or more.

[0132] Drying may be carried out by known methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is carried out so that the content of organic solvent in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the organic solvent in the resin composition or resin varnish, for example, when a resin composition or resin varnish containing 30% by mass to 60% by mass of organic solvent is used, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0133] The resin sheet can be stored in a rolled state. When the resin sheet has a protective film, the resin sheet can be used by peeling off the protective film.

[0134] In one embodiment, the prepreg is formed by impregnating a sheet-like fiber substrate with the resin composition of the present invention.

[0135] The sheet-like fiber substrate used for the prepreg is not particularly limited, and commonly used prepreg substrates such as glass cloth, aramid nonwoven fabric, and liquid crystal polymer nonwoven fabric can be used. From the viewpoint of thinning printed wiring boards and semiconductor chip packages, the thickness of the sheet-like fiber substrate is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less. The lower limit of the thickness of the sheet-like fiber substrate is not particularly limited. The lower limit of the thickness of the sheet-like fiber substrate is usually 10 μm or more.

[0136] The prepreg can be produced by a known method such as a hot melt method or a solvent method.

[0137] The thickness of the prepreg may be in the same range as that of the resin composition layer in the resin sheet described above.

[0138] The sheet-like laminate material of the present invention can be suitably used to form an insulating layer of a printed wiring board (for the insulating layer of a printed wiring board), and can be more suitably used to form an interlayer insulating layer of a printed wiring board (for the interlayer insulating layer of a printed wiring board). The sheet-like laminate material of the present invention can also be suitably used to form an insulating layer of a rewiring board of a semiconductor package (for the insulating layer of a rewiring board). That is, the sheet-like laminate material of the present invention can be suitably used as an insulating layer of a circuit board.

[0139] [Circuit Board] The resin composition of the present invention can be used to form an insulating layer for a circuit board. The present invention also provides such a circuit board, i.e., a circuit board including an insulating layer made of a cured product of the resin composition of the present invention.

[0140] <Printed Wiring Board> In one embodiment, the circuit board of the present invention is a printed wiring board.

[0141] A printed wiring board can be produced, for example, by using the above-mentioned resin sheet by a method including the following steps (I) and (II): (I) a step of laminating a resin sheet on an inner layer substrate so that the resin composition layer of the resin sheet is bonded to the inner layer substrate; and (II) a step of curing (e.g., thermally curing) the resin composition layer to form an insulating layer.

[0142] The "inner layer substrate" used in step (I) is a member that will become the substrate of a printed wiring board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may have a conductor layer on one or both sides, and this conductor layer may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate is sometimes referred to as an "inner layer circuit board." Furthermore, intermediate products on which an insulating layer and / or a conductor layer is to be further formed during the production of a printed wiring board are also included in the "inner layer substrate" of the present invention. When the printed wiring board is a circuit board with built-in components, an inner layer substrate with built-in components may be used.

[0143] The lamination of the inner layer substrate and the resin sheet can be carried out, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). The thermocompression bonding member may be pressed directly onto the resin sheet, or may be pressed 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.

[0144] The lamination of the inner layer substrate and the resin sheet may be carried out 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 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination may be carried out under reduced pressure conditions, preferably a pressure of 26.7 hPa or less.

[0145] The 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.

[0146] After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0147] The support may be removed between step (I) and step (II), or may be removed after step (II). When a metal foil is used as the support, the conductor layer may be formed using the metal foil without peeling off the support. When a metal foil with a supporting substrate is used as the support, the supporting substrate (and the release layer) may be peeled off. Then, the conductor layer can be formed using the metal foil.

[0148] In step (II), the resin composition layer is cured (for example, by heat curing) to form an insulating layer made of a cured product of the resin composition. The curing conditions for the resin composition layer are not particularly limited, and conditions typically employed for forming insulating layers for printed wiring boards may be used.

[0149] For example, the heat curing conditions for the resin composition layer vary depending on the type of resin composition, etc., but in one embodiment, the curing temperature is preferably 140° C. to 250° C., more preferably 150° C. to 240° C., and even more preferably 160° C. to 230° C. The curing time is preferably 5 minutes to 240 minutes, more preferably 10 minutes to 150 minutes, and even more preferably 15 minutes to 120 minutes.

[0150] Before thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature of 50°C to 140°C, preferably 60°C to 135°C, more preferably 70°C to 130°C for 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.

[0151] When manufacturing a printed wiring board, the following steps may be further performed: (III) drilling holes in the insulating layer; (IV) roughening the insulating layer; and (V) forming a conductor layer. These steps (III) to (V) may be performed according to various methods known to those skilled in the art for use in manufacturing printed wiring boards. When the support is removed after step (II), the support may be removed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V). Furthermore, if necessary, the formation of the insulating layer and the conductor layer in steps (I) to (V) may be repeated to form a multilayer wiring board.

[0152] In another embodiment, the printed wiring board of the present invention can be produced using the above-mentioned prepreg. The production method is basically the same as when a resin sheet is used.

[0153] Step (III) is a step of drilling holes in the insulating layer, thereby forming holes such as via holes and through holes in the insulating layer. Step (III) may be performed using, for example, a drill, a laser, plasma, or the like, depending on the composition of the resin composition used to form the insulating layer. The dimensions and shape of the holes may be determined appropriately depending on the design of the printed wiring board.

[0154] Step (IV) is a step of roughening the insulating layer. Usually, in this step (IV), smear removal (desmear) is also performed. The procedure and conditions of the roughening treatment are not particularly limited, and known procedures and conditions that are usually used when forming an insulating layer of a printed wiring board can be adopted. For example, the insulating layer can be roughened by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order.

[0155] The swelling liquid used in the roughening treatment is not particularly limited, but examples thereof include alkaline solutions and surfactant solutions, and is preferably an alkaline solution, with sodium hydroxide solution and potassium hydroxide solution being more preferred. Commercially available swelling liquids include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. The swelling treatment using a swelling liquid is not particularly limited, but can be carried out by, for example, immersing the insulating layer in a 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 a swelling liquid at 40°C to 80°C for 5 to 15 minutes.

[0156] The oxidizing agent used in the roughening treatment is not particularly limited, but examples thereof include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidizing agent such as an 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," "Concentrate Compact P," and "Dosing Solution Securigans P" manufactured by Atotech Japan.

[0157] 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 is an example.

[0158] The treatment with the neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30° C. to 80° C. for 5 to 30 minutes. From the viewpoint of workability, etc., a method in which the object that has been roughened with an oxidizing agent is immersed in a neutralizing solution at 40° C. to 70° C. for 5 to 20 minutes is preferred.

[0159] Step (V) is a step of forming a conductor layer, and the conductor layer is formed on the insulating layer. The conductor 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 the alloy layer include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

[0160] The conductor layer may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are stacked. 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.

[0161] The thickness of the conductor layer depends on the desired design of the printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0162] The conductor layer may be formed using a metal foil. When a conductor layer is formed using a metal foil, it is preferable to perform step (V) between step (I) and step (II). For example, after step (I), the support is removed and a metal foil is laminated on the exposed surface of the resin composition layer. The lamination of the resin composition layer and the metal foil may be performed by a vacuum lamination method. The lamination conditions may be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Thereafter, a conductor layer having a desired wiring pattern can be formed using the metal foil on the insulating layer by a conventional known technique such as a modified semi-additive method.

[0163] The metal foil can be produced by a known method such as an electrolytic method, a rolling method, etc. Examples of commercially available metal foils include HLP foil and JXUT-III foil manufactured by JX Nippon Mining & Smelting Corporation, and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd.

[0164] Alternatively, when a metal foil or a metal foil with a supporting substrate is used as the support for the resin sheet, the conductor layer may be formed using the metal foil, as described above.

[0165] In another embodiment, the conductor layer may be formed by plating. When forming the conductor layer by plating, it is preferable to form it by a semi-additive method from the viewpoint of facilitating the formation of fine wiring. An example of forming the conductor layer by a semi-additive method will be described below.

[0166] First, a plating seed layer is formed on the surface of an insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. After a metal layer is formed on the exposed plating seed layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, thereby forming a conductor layer having the desired wiring pattern.

[0167] <Rewiring Substrate of Semiconductor Package> In one embodiment, the circuit board of the present invention is a rewiring substrate (rewiring layer) of a semiconductor package. Hereinafter, a method for manufacturing a semiconductor package will be described.

[0168] The semiconductor package includes an insulating layer made of a cured product of the resin composition of the present invention as an insulating layer of a rewiring substrate. The semiconductor package may also include a sealing layer made of a cured product of the resin composition of the present invention.

[0169] A semiconductor package can be manufactured, for example, by a method including the following steps (1) to (6) using the resin composition and resin sheet of the present invention. The resin composition and resin sheet of the present invention can be used to form a rewiring formation layer (insulating layer for forming a rewiring substrate) in step (5) or a sealing layer in step (3). An example of forming a rewiring formation layer or a sealing layer using a resin composition or a resin sheet will be shown below. However, techniques for forming a rewiring formation layer or a sealing layer for a semiconductor package are known, and a person skilled in the art can manufacture a semiconductor package using the resin composition and resin sheet of the present invention according to known techniques. (1) A step of laminating a temporary fixing film on a substrate; (2) A step of temporarily fixing a semiconductor chip on the temporary fixing film; (3) A step of forming a sealing layer on the semiconductor chip; (4) A step of peeling the substrate and the temporary fixing film from the semiconductor chip; (5) A step of forming a rewiring formation layer as an insulating layer on the surface of the semiconductor chip from which the substrate and the temporary fixing film have been peeled; and (6) A step of forming a rewiring layer as a conductor layer on the rewiring formation layer.

[0170] -Step (1)- The material used for the substrate is not particularly limited. Examples of the substrate include semiconductor wafers such as silicon wafers, glass wafers, glass substrates, metal substrates such as copper, titanium, stainless steel, and cold-rolled steel plate (SPCC), substrates in which glass fibers are impregnated with epoxy resin or the like and subjected to a thermosetting treatment (e.g., FR-4 substrates), and substrates made of bismaleimide triazine resin (BT resin).

[0171] The material of the temporary fixing film is not particularly limited as long as it can be peeled off from the semiconductor chip in step (4) and can temporarily fix the semiconductor chip. Commercially available products can be used as the temporary fixing film. Examples of commercially available products include Riva Alpha manufactured by Nitto Denko Corporation.

[0172] -Step (2)- The semiconductor chips can be temporarily fixed using known devices such as a flip chip bonder, a die bonder, etc. The layout and number of semiconductor chips to be arranged can be set appropriately depending on the shape and size of the temporary fixing film, the number of semiconductor packages to be produced, etc. For example, the semiconductor chips can be temporarily fixed by arranging them in a matrix of multiple rows and multiple columns.

[0173] -Step (3)- A resin composition layer of the resin sheet of the present invention is laminated on a semiconductor chip, or the resin composition of the present invention is applied on a semiconductor chip and cured (for example, thermally cured) to form an encapsulating layer.

[0174] For example, lamination of a semiconductor chip and a resin sheet can be performed by removing the protective film from the resin sheet and then thermocompressing the resin sheet to the semiconductor chip from the support side. Examples of a member for thermocompressing the resin sheet to the semiconductor chip (hereinafter also referred to as a "thermocompression member") include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). It is preferable to press the thermocompression member not directly onto the resin sheet, but via an elastic material such as heat-resistant rubber, so that the resin sheet can adequately conform to the surface irregularities of the semiconductor chip. The semiconductor chip and the resin sheet can also be laminated by a vacuum lamination method, and the lamination conditions and preferred ranges are the same as those described in connection with the method for manufacturing a printed wiring board.

[0175] After lamination, the resin composition is thermally cured to form the sealing layer under the same conditions as those described in relation to the method for producing a printed wiring board.

[0176] The support of the resin sheet may be peeled off after the resin sheet is laminated on the semiconductor chip and thermally cured, or the support may be peeled off before the resin sheet is laminated on the semiconductor chip.

[0177] When forming a sealing layer by applying the resin composition of the present invention, the application conditions are the same as the application conditions when forming the resin composition layer described in relation to the resin sheet of the present invention, and the preferred ranges are also the same.

[0178] -Step (4)- The method for peeling off the substrate and the temporary fixing film can be changed as appropriate depending on the material of the temporary fixing film, etc., and examples thereof include a method in which the temporary fixing film is heated and foamed (or expanded) to peel off, and a method in which ultraviolet light is irradiated from the substrate side to reduce the adhesive strength of the temporary fixing film and then peel it off.

[0179] In the method of heating and foaming (or expanding) the temporary fixing film to peel it off, the heating conditions are usually 100°C to 250°C for 1 second to 90 seconds or 5 minutes to 15 minutes. In the method of irradiating ultraviolet light from the substrate side to reduce the adhesive strength of the temporary fixing film to peel it off, the irradiation dose of ultraviolet light is usually 10 mJ / cm. ２ ~1000mJ / cm ２ is.

[0180] -Step (5)- A rewiring formation layer (insulating layer of a rewiring substrate) is formed using the resin composition and resin sheet of the present invention.

[0181] After forming the redistribution layer, via holes may be formed in the redistribution layer to connect the semiconductor chip to a conductor layer (described later). The via holes may be formed by a known method depending on the material of the redistribution layer.

[0182] Step (6)—The formation of a conductor layer on the rewiring formation layer may be carried out in the same manner as step (V) described in relation to the method for producing a printed wiring board. Steps (5) and (6) may be repeated to alternately stack (build up) conductor layers (rewiring layers) and rewiring formation layers (insulating layers).

[0183] In manufacturing the semiconductor package, the steps of (7) forming a solder resist layer on the conductor layer (rewiring layer), (8) forming bumps, and (9) dicing the plurality of semiconductor packages into individual semiconductor packages may be further performed. These steps may be performed according to various methods used in manufacturing semiconductor packages and known to those skilled in the art.

[0184] By forming a rewiring formation layer (insulating layer) using the resin composition or resin sheet of the present invention, which can provide a cured product that has a low dielectric loss tangent, can suppress warpage after curing, and has excellent reflow resistance, it is possible to realize a semiconductor package with extremely low transmission loss, regardless of whether the semiconductor package is a fan-in (Fan-In) package or a fan-out (Fan-Out) package. In one embodiment, the semiconductor package of the present invention is a fan-out (Fan-Out) package. The resin composition and resin sheet of the present invention can be applied to both fan-out panel level packages (FOPLPs) and fan-out wafer level packages (FOWLPs). In one embodiment, the semiconductor package of the present invention is a fan-out panel level package (FOPLP) or a fan-out wafer level package (FOWLP).

[0185] [Semiconductor Device] The semiconductor device of the present invention includes a layer made of a cured product of the resin composition of the present invention. The semiconductor device of the present invention can be produced using the circuit board of the present invention.

[0186] Examples of semiconductor devices include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft).

[0187] 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.

[0188] Synthesis Example 1 Synthesis of Elastomer A1 To a flask equipped with a stirrer, a thermometer, and a condenser were placed 770.1 g of propylene glycol methyl ether acetate (hereinafter, may be referred to as "PGMAc"), 67.5 g (0.30 mol) of isophorone diisocyanate (hereinafter, may be referred to as "IPDI"), 562.6 g (0.15 mol) of polybutadiene having OH groups at both ends ("G-3000" manufactured by Nippon Soda Co., Ltd., Mn: 3,000, hydroxyl value: 30.3 mgKOH / g), 0.28 g of zirconium dibutoxybis(ethylacetoacetate) ("Orgatix ZC-580" manufactured by Matsumoto Fine Chemical Co., Ltd.), and 0.14 g of a zinc complex ("K-KAT XK-614" manufactured by Kusumoto Chemicals Co., Ltd.). The mixed solution was heated to 60°C and then maintained at this temperature for 4 hours. 16.6 g (0.076 mol) of pyromellitic anhydride was added to the mixed solution. The mixed solution was then heated to 140°C, and the reaction was continued for 4 hours.

[0189] After it was confirmed that the increase in viscosity of the mixed solution had subsided, it was cooled to 120° C. Thereafter, 20.0 g of 2-hydroxyethyl methacrylate (0.15 mol) and 0.37 g of methoquinone were added, and the reaction was carried out at 120° C. for 2 hours.

[0190] Characteristic absorption was measured in the infrared spectrum, and the characteristic absorption of the isocyanate group at 2270 cm －１ After confirming that the absorption peak had completely disappeared, the solution was adjusted to 45% by mass of nonvolatile components using PGMAc. The above procedure yielded Elastomer A1 (a solution containing 45% by mass of nonvolatile components) having methacryloyl groups at its ends. The weight-average molecular weight (Mw) of Elastomer A1 measured by GPC was 13,000.

[0191] The elastic modulus of the resulting elastomer A1 was measured using the following elastic modulus measurement method. A polyethylene terephthalate film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C) was prepared, which had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation). Elastomer A1 was uniformly applied to the support using a die coater so that the dried resin layer would have a thickness of 50 μm. The film was then dried for a total of 10 minutes in an oven heated from 70°C to 120°C at a rate of 10°C / min, thereby forming a resin layer of elastomer A1 with a volatile component content of 1% by mass or less relative to 100% by mass of all components of elastomer A1. The dried resin layer was peeled from the support and punched into the shape of a Type 5 test piece as specified in JIS K 7127. The elastic modulus of this was measured by a tensile test (temperature 25°C, humidity 40% RH, tensile speed 5 mm / min) in accordance with JIS K7161. The elastic modulus of Elastomer A1 was 0.02 GPa.

[0192] Synthesis Example 2 Synthesis of Elastomer A2 A flask equipped with a stirrer, a thermometer, and a condenser was charged with 727.2 g of PGMAc, 135.9 g (0.61 mol) of IPDI, 459.1 g (0.31 mol) of polybutadiene terminated with OH groups ("G-1000" manufactured by Nippon Soda Co., Ltd., Mn: 1,400, hydroxyl value: 74.8 mg KOH / g), 0.26 g of zirconium dibutoxybis(ethylacetoacetate) ("Orgatix ZC-580" manufactured by Matsumoto Fine Chemical Co., Ltd.), and 0.13 g of zinc complex ("K-KAT XK-614" manufactured by Kusumoto Chemicals Co., Ltd.). The mixture was heated to 60°C and then maintained at this temperature for 4 hours. To this mixed solution, 33.4 g (0.15 mol) of pyromellitic anhydride was added, and then the mixed solution was heated to 140° C., and the reaction was continued for 4 hours.

[0193] After it was confirmed that the increase in viscosity of the mixed solution had subsided, it was cooled to 120° C. Thereafter, 40.2 g of 2-hydroxyethyl methacrylate (0.31 mol) and 0.34 g of methoquinone were added, and the reaction was carried out at 120° C. for 2 hours.

[0194] Characteristic absorption was measured in the infrared spectrum, and the characteristic absorption of the isocyanate group at 2270 cm －１ After confirming that the absorption peak of β-glucan had completely disappeared, the solution was adjusted to 45% by mass of nonvolatile components using PGMAc. Using the above procedure, Elastomer A2 (solution containing 45% by mass of nonvolatile components) having methacryloyl groups at its ends was synthesized. The weight average molecular weight (Mw) of Elastomer A2 measured by GPC was 22,000.

[0195] The modulus of elasticity of Elastomer A2 was measured in the same manner as that of Elastomer A1, and was found to be 0.01 GPa.

[0196] Synthesis Example 3: Synthesis of Elastomer A3 A flask equipped with a stirrer, thermometer, and condenser was charged with 727.2 g of PGMAc, 135.9 g (0.61 mol) of IPDI, 459.1 g (0.31 mol) of polybutadiene terminated with OH groups ("G-1000" manufactured by Nippon Soda Co., Ltd.), 0.26 g of zirconium tetraacetylacetonate ("Orgatix ZC-150" manufactured by Matsumoto Fine Chemical Co., Ltd.), and 0.13 g of titanium diisopropoxybis(ethylacetoacetate) ("Orgatix TC-750" manufactured by Matsumoto Fine Chemical Co., Ltd.). The resulting mixture was heated to 60°C and maintained at this temperature for 4 hours. 49.3 g (0.15 mol) of benzophenonetetracarboxylic dianhydride was then added to the resulting mixture. Thereafter, the mixed solution was heated to 140° C., and the reaction was continued for 4 hours.

[0197] After it was confirmed that the increase in viscosity of the mixed solution had subsided, it was cooled to 120° C. Thereafter, 34.8 g of 2-hydroxyethyl acrylate (0.30 mol) and 0.34 g of methoquinone were added, and the reaction was carried out at 120° C. for 2 hours.

[0198] Characteristic absorption was measured in the infrared spectrum, and the characteristic absorption of the isocyanate group at 2270 cm －１It was confirmed that the absorption peak of α-methyl-2-propanol completely disappeared. The reaction mixture was then adjusted using PGMAc so that the nonvolatile content was 45% by mass. In this manner, an acryloyl-terminated elastomer A3 (a solution containing 45% by mass of nonvolatile components) was obtained. The weight-average molecular weight (Mw) of elastomer A3 measured by GPC was 16,000.

[0199] The modulus of elasticity of Elastomer A3 was measured in the same manner as that of Elastomer A1, and was found to be 0.05 GPa.

[0200] Synthesis Example 4 Synthesis of Elastomer A4 A flask equipped with a stirrer, a thermometer, and a condenser was charged with 770.1 g of PGMAc, 67.5 g (0.30 mol) of IPDI, 300.0 g (0.15 mol) of polycarbonate diol ("C-2015N" manufactured by Kuraray Co., Ltd., Mn: approximately 2000, hydroxyl equivalent: 1000 g / eq.), 0.28 g of zirconium dibutoxybis(ethylacetoacetate) ("Orgatix ZC-580" manufactured by Matsumoto Fine Chemical Co., Ltd.), and 0.14 g of zinc complex ("K-KAT XK-614" manufactured by Kusumoto Chemicals Co., Ltd.). The mixed solution was heated to 60°C and then maintained at this temperature for 4 hours.

[0201] To this mixed solution, 16.6 g (0.076 mol) of pyromellitic anhydride was added. Thereafter, the mixed solution was heated to 140°C, and the reaction was continued for 4 hours. After confirming that the increase in viscosity of the mixed solution had subsided, the solution was cooled to 120°C. Thereafter, 20.0 g of 2-hydroxyethyl methacrylate (0.15 mol) and 0.37 g of methoquinone were added, and the reaction was carried out at 120°C for 2 hours.

[0202] Characteristic absorption was measured in the infrared spectrum, and the characteristic absorption of the isocyanate group at 2270 cm －１ After confirming that the absorption peak had completely disappeared, the solution was adjusted to 45% by mass of nonvolatile components using PGMAc. The above procedure yielded Elastomer A4 (a solution containing 45% by mass of nonvolatile components) having methacryloyl groups at its ends. The weight-average molecular weight (Mw) of Elastomer A4 measured by GPC was 150,000.

[0203] The modulus of elasticity of Elastomer A4 was measured in the same manner as that of Elastomer A1, and was found to be 0.05 GPa.

[0204] Synthesis Example 5: Synthesis of Elastomer A5 69 g of polybutadiene terminated with OH groups ("G-3000" manufactured by Nippon Soda Co., Ltd.), 40 g of propylene glycol monomethyl ether acetate ("PGMEA" manufactured by Resonac Corporation), and 0.005 g of dibutyltin laurate were placed in a reaction vessel and mixed to dissolve uniformly. Once uniform, the temperature was raised to 60°C, and 8 g of isophorone diisocyanate ("IPDI" manufactured by Evonik Degussa Japan Co., Ltd., isocyanate group equivalent: 113 g / eq.) was added with further stirring, and the reaction was carried out for approximately 3 hours.

[0205] Next, 23 g of cresol novolak resin ("KA-1160" manufactured by DIC Corporation, hydroxyl group equivalent: 117 g / eq.) and 60 g of propylene glycol monomethyl ether acetate ("PGMEA" manufactured by Resonac Corporation) were added to the reaction mixture, and the mixture was refluxed at 150°C with stirring and reacted for about 10 hours. －１ The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end of the reaction, and the reaction mixture was cooled to room temperature. The reaction mixture was then filtered through a 100-mesh filter cloth to obtain Elastomer A5 having a butadiene structure and phenolic hydroxyl groups (phenolic hydroxyl group-containing butadiene resin: solution containing 50% by mass of non-volatile components). Elastomer A5 does not have radically polymerizable groups at the molecular terminals. The weight-average molecular weight (Mw) of Elastomer A5 measured by GPC was 27,000.

[0206] The modulus of elasticity of Elastomer A5 was measured in the same manner as that of Elastomer A1, and was found to be 0.05 GPa.

[0207] Synthesis Example 6: Synthesis of Vinyl Resin B1 201 g of orthoallylphenol and 1,000 g of toluene were charged into a reaction vessel and dissolved while the vessel was purged with nitrogen under reduced pressure. Subsequently, 152 g of isophthalic acid chloride was charged and dissolved. While purging the vessel with nitrogen, 309 g of a 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. The temperature in the system was controlled to 60°C or less. The mixture was then stirred for 1 hour to react. After the reaction was completed, the reaction mixture was separated and the aqueous layer was removed. This operation was repeated until the pH of the aqueous layer reached 7, and toluene and other components were distilled off under heating and reduced pressure to obtain Vinyl Resin B1. The unsaturated bond equivalent of the resulting Vinyl Resin B1 was calculated from the charge ratio to be 199 g / eq.

[0208] Synthesis Example 7: Synthesis of Vinyl Resin B2 A flask equipped with a thermometer, dropping funnel, condenser, distillation column, and stirrer was charged with 165 g of a polyaddition reaction resin of dicyclopentadiene and phenol (hydroxyl equivalent: 165 g / eq., softening point 85°C), 134 g (1.0 mol) of ortho-allylphenol, and 1,200 g of toluene, and the system was purged with nitrogen under reduced pressure. Next, 203 g (1.0 mol) of isophthalic acid chloride was charged, and the system was purged with nitrogen under reduced pressure. 0.6 g of tetrabutylammonium bromide was added, and while purging with nitrogen gas, the system was controlled to 60°C or less, and 412 g of a 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. After the addition, the mixture was stirred for 1.0 hour. After the reaction was completed, the aqueous layer was removed by static separation. Water was further added to the obtained toluene layer and stirred for 15 minutes, and the aqueous layer was removed by static separation. This operation was repeated until the pH of the aqueous layer reached 7. The nonvolatile content was then adjusted to 70% by mass by heat drying, thereby obtaining a vinyl resin B2 represented by the following chemical formula.

[0209]

[0210] In the above chemical formula, each s is independently an integer of 0 or 1 or greater, and the average value of r calculated from the charge ratio is 1. The dashed line in the chemical formula represents a structure obtained by reacting isophthalic acid chloride with a phenol polyaddition reaction resin and / or ortho-allylphenol. The unsaturated bond equivalent of the obtained vinyl resin B2 was calculated from the charge ratio and was found to be 428 g / eq.

[0211] Synthesis Example 8 Synthesis of Maleimide Resin B3 An MEK solution (60% by mass of non-volatile components) of maleimide resin B3 (Mw / Mn=1.81, t″=1.47 (mainly 1, 2, or 3)) synthesized by the method described in Synthesis Example 1 of the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211 was prepared. This maleimide resin B3 has a structure represented by the following formula.

[0212]

[0213] Examples 1 to 12 and Comparative Examples 1 and 2: Preparation of Resin Compositions Each component was weighed out in the amount of parts by mass shown in Table 1 below, and then 15 parts of MEK (methyl ethyl ketone) and 15 parts of cyclohexanone were added and mixed together, followed by uniform dispersion using a high-speed rotary mixer to obtain a resin composition (resin varnish). Details of each component shown in Table 1 below are as follows:

[0214] (A) High-molecular-weight, low-elasticity compound having a radically polymerizable group at its terminal (a compound having a radically polymerizable group at its terminal, a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161) - "Elastomer A1": Elastomer A1 obtained in Synthesis Example 1 - "Elastomer A2": Elastomer A2 obtained in Synthesis Example 2 - "Elastomer A3": Elastomer A3 obtained in Synthesis Example 3 - "Elastomer A4": Elastomer A4 obtained in Synthesis Example 4

[0215] (A') A high-molecular-weight, low-elasticity compound having no terminal radical polymerizable groups (a compound having no terminal radical polymerizable groups, a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161). "Elastomer A5": Elastomer A5 obtained in Synthesis Example 5

[0216] (B) Inorganic filler "SO-C2": Spherical silica (manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-573"). ２ / g) "Alumina B": spherical alumina (average particle size 1.0 μm) surface-treated with an aminosilane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.)

[0217] (C) Compounds Having a Radically Polymerizable Group (Compounds Having a Radical Polymerizable Group and Having a Weight-Average Molecular Weight (Mw) of 5,000 or Less) "OPE-2St 1200": Vinylbenzyl-Modified Polyphenylene Ether (Mitsubishi Gas Chemical Company, Inc., toluene solution with a non-volatile content of 65%, number-average molecular weight (Mn): 1,200) "BMI-689": Aliphatic Maleimide Resin (N-Alkylbismaleimide Having a Skeleton Derived from Dimer Diamine, Designer Molecules Inc.) "BMI-1500": Aliphatic Maleimide Resin (N-Alkylbismaleimide Having a Skeleton Derived from Dimer Diamine, Designer Molecules Inc.) "MIR-3000-70MT": Aromatic Maleimide Resin (Nippon Kayaku Co., Ltd., MEK / Toluene Mixed Solution with a Non-volatile Content of 70%) "MIR-5000-60T": aromatic maleimide resin (manufactured by Nippon Kayaku Co., Ltd., toluene solution with a non-volatile content of 60%); "SA9000": methacrylic-modified polyphenylene ether (manufactured by SABIC); "A-DOG": dioxane glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.); "DAD": diallyl diphenate (manufactured by Nisshoku Techno Fine Chemical Co., Ltd.); "DCP": tricyclodecane dimethanol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.); "Petrotack 70": aliphatic / aromatic copolymer hydrocarbon resin containing 50% by mass of hydrocarbons with 5 carbon atoms (manufactured by Tosoh Corporation, propenyl resin with an active group equivalent of less than 250 g / eq.). "Petrotack 90" aromatic copolymer hydrocarbon resin containing 30% by mass of hydrocarbons having 5 carbon atoms (manufactured by Tosoh Corporation, a propenyl resin having an active group equivalent of 250 g / eq. or more); "HYBRAR 5125": vinyl group-containing polystyrene isoprene resin (manufactured by Kuraray Co., Ltd.); "Vinyl resin B1": vinyl resin B1 obtained in Synthesis Example 6; "Vinyl resin B2": vinyl resin B2 obtained in Synthesis Example 7; "Maleimide resin B3": maleimide resin B3 obtained in Synthesis Example 8.

[0218] (D) Radical polymerization initiator "Luperox DTA": di-t-amyl peroxide (manufactured by Arkema Yoshitomi Co., Ltd.) "Perbutyl C": t-butylcumyl peroxide (manufactured by NOF Corporation)

[0219] (E) Polymer Resin "EXL2655": Core-shell type graft copolymer rubber particles (manufactured by The Dow Chemical Company)

[0220] <Preparation of Resin Sheet> A polyethylene terephthalate film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130° C.) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared as a support. Each of the resin compositions obtained in Examples 1 to 12 and Comparative Examples 1 and 2 was uniformly applied onto the support using a die coater so that the thickness of the resin composition layer after drying would be 50 μm, and the resulting film was dried at 70° C. to 90° C. for 3 minutes to form a resin composition layer on the support.

[0221] After the resin composition layer was subjected to <Test Example 4: Evaluation of Appearance of Resin Composition Layer> described below, the rough surface of a polypropylene film ("Alphan MA-411" manufactured by Oji F-Tex Co., Ltd., thickness 15 μm) was attached as a protective film to the surface of the resin composition layer that was not bonded to the support, thereby obtaining a resin sheet having the support / resin composition layer / protective film in this order.

[0222] Test Example 1: Measurement of Dielectric Loss Tangent (Df) The protective film was peeled off from the resin sheet, and the resin composition layer was thermally cured by heating at 200°C for 90 minutes. The support was then peeled off to obtain a cured product. The obtained cured product was cut into a width of 2 mm and a length of 80 mm to obtain a test piece for evaluation. The dielectric loss tangent (Df value) of this test piece was measured using a cavity resonance perturbation method using a measuring device (Agilent Technologies' "HP8362B") at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. Measurements were performed on three test pieces, and the average value was calculated. Based on this average value, the dielectric loss tangent was evaluated according to the following criteria. [Evaluation Criteria for Dielectric Loss Tangent (Df)] "○": The dielectric loss tangent (Df value) is less than 0.003. "△": The dielectric loss tangent (Df value) is 0.003 or more and 0.0035 or less. "×": The dielectric loss tangent (Df value) is greater than 0.0035.

[0223] <Test Example 2: Warpage Measurement Test> The resin sheet from which the protective film had been peeled off was laminated onto the entire surface of one side of a 12-inch silicon wafer (thickness 775 μm) using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"). This lamination was performed so that the resin composition layer and the silicon wafer were bonded. The support of the resin sheet was peeled off to expose the resin composition layer. A resin sheet from which the protective film had been peeled off was similarly laminated on the surface of this exposed resin composition layer, and the support was peeled off to form two resin composition layers (total thickness 100 μm) on one side of the 12-inch silicon wafer. The lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at 100 ° C. and a pressure of 0.74 MPa for 30 seconds.

[0224] Next, the silicon wafer on which the resin composition layer was laminated was heated in an oven at 100° C. for 30 minutes, and further heated at 200° C. for 90 minutes. By such heating, the resin composition layer was cured, and a sample laminate X having a layer structure of "silicon wafer / cured product layer" was obtained.

[0225] The amount of warpage of the obtained sample laminate X was measured using a shadow moiré measurement device ("Thermoire AXP" manufactured by Akorometrix). The measurement was performed in accordance with JEITA EDX-7311-24, a standard of the Japan Electronics and Information Technology Industries Association. Specifically, a virtual plane calculated using the least squares method for all data on the evaluation substrate surface (the surface of the cured product layer opposite the silicon wafer) in the measurement area was used as a reference plane, and the difference between the minimum and maximum values ​​of the vertical height from the reference plane to the evaluation substrate surface was calculated as the amount of warpage. The measured values ​​of the amount of warpage obtained were evaluated according to the following criteria. A smaller amount of warpage indicates more effective suppression of warpage. [Evaluation Criteria for Warpage] "○": The amount of warpage is 0 μm or more and 2,000 μm or less. "△": The amount of warpage is more than 2,000 μm and less than 2,500 μm. "×": The amount of warpage is 2,500 μm or more.

[0226] Test Example 3: Evaluation Test for Reflow Resistance (1) Copper Foil Primer Treatment The shiny side of an electrolytic copper foil ("3EC-III" manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 35 μm) was etched by 1 μm with an etching agent ("CZ8101" manufactured by MEC Co., Ltd.) to roughen the copper surface. Next, the roughened surface of the copper foil was subjected to a rust prevention treatment using a rust inhibitor ("CL8300" manufactured by MEC Co., Ltd.). This copper foil was further heat-treated in an oven at 130° C. for 30 minutes to obtain a CZ-treated copper foil.

[0227] (2) Preparation of Inner Layer Substrate: A glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness: 18 μm, substrate thickness: 0.4 mm, Panasonic "R1515A") was prepared as the inner layer substrate. Both sides of this inner layer substrate were etched to a depth of 1 μm using an etching agent (MEC "CZ8101") to roughen the copper surface. Furthermore, this inner layer substrate was subjected to a heat treatment in an oven at 130°C for 30 minutes.

[0228] (3) Lamination of Resin Composition Layer The protective film was peeled off from the resin sheet to expose the resin composition layer. Using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"), resin sheets were laminated on both sides of the inner layer substrate so that the resin composition layer was in contact with the inner layer substrate. The lamination was carried out by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing at 120 ° C and a pressure of 0.74 MPa for 30 seconds. Next, a heat press was performed at 100 ° C and a pressure of 0.5 MPa for 60 seconds. Thereafter, the support was peeled off to expose the resin composition layer.

[0229] (4) Lamination of Copper Foil and Curing of Resin Composition Layer The treated surface of the CZ-treated copper foil was laminated onto the exposed resin composition layer under the same conditions as in "(3) Lamination of Resin Composition Layer" above. The resin composition layer was then thermally cured at 200°C for 90 minutes to form an insulating layer as a cured product layer. This resulted in an evaluation substrate Y having a layer structure of CZ-treated copper foil / insulating layer / inner layer substrate / insulating layer / CZ-treated copper foil.

[0230] (5) Reflow Resistance Evaluation Test The evaluation board Y was cut into small pieces of 100 mm x 50 mm to obtain test pieces. These test pieces were subjected to a test in which they were subjected to a reflow apparatus ("HAS-6116" manufactured by Nippon Antom Co., Ltd.) 10 times, which reproduces a solder reflow temperature of a peak temperature of 260°C (the reflow temperature profile conforms to IPC / JEDEC J-STD-020C). This test was performed on five test pieces. After the test, the test pieces were visually observed, and the reflow resistance was evaluated according to the following criteria. [Evaluation of Reflow Resistance] "○": No abnormalities such as blistering were observed in the CZ-treated copper foil in any of the test pieces. "△": An abnormality such as blistering was observed in the CZ-treated copper foil in one test piece. "×": An abnormality such as blistering was observed in the CZ-treated copper foil in two or more test pieces.

[0231] Test Example 4: Evaluation of Appearance of Resin Composition Layer The resin composition layer was visually observed in the resin sheet before the protective film was attached. Based on this visual observation, the appearance of the resin composition layer was evaluated according to the following criteria. [Evaluation of Appearance of Resin Composition Layer] "◯": No unevenness or cissing is present throughout the resin composition layer. "Δ": Unevenness or cissing is present in a portion of the resin composition layer. "×": Unevenness or cissing is present throughout the resin composition layer.

[0232]

Claims

1. A resin composition comprising: (A) a compound having a radically polymerizable group at its terminal, a weight-average molecular weight (Mw) of more than 5,000 and not more than 300,000, and a tensile modulus of elasticity of 1 GPa or less as measured at 25°C in accordance with JIS K7161; (B) an inorganic filler; and (C) a compound having a radically polymerizable group and a weight-average molecular weight (Mw) of 5,000 or less.

2. The resin composition according to claim 1, wherein component (A) contains an imide skeleton.

3. The resin composition according to claim 1, wherein component (A) contains an imide skeleton in the main chain.

4. The resin composition according to claim 1, wherein component (A) contains a structure represented by the following formula (A-1): (In formula (A-1), R Ａ１ represents a tetravalent group obtained by removing an acid anhydride group from a tetracarboxylic dianhydride; * represents a bond.

5. The resin composition according to claim 4, wherein the component (A) contains a structure represented by the formula (A-1) in combination with a structure represented by the following formula (A-3): (In formula (A-3), R Ａ３ represents a divalent group obtained by removing two hydroxyl groups from a polyol compound having two or more hydroxyl groups in one molecule; * represents a bond.

6. The resin composition according to claim 1, wherein the content of component (B) is 50% by mass or more relative to 100% by mass of the non-volatile components of the resin composition.

7. The resin composition according to claim 1, wherein component (A) contains one or more structural units selected from the group consisting of polyolefin structural units, polycarbonate structural units, polyether structural units, polyester structural units, poly(meth)acrylic structural units, and polysiloxane structural units.

8. The resin composition according to claim 1, wherein component (A) contains a polyolefin structural unit.

9. The resin composition according to claim 1, wherein component (C) comprises a maleimide-based radical polymerizable compound.

10. A resin composition according to claim 1, wherein the content of component (A) is 0.1% by mass or more and 30% by mass or less, based on 100% by mass of the non-volatile components of the resin composition.

11. The resin composition according to claim 1, wherein the content of component (C) is 5% by mass or more and 40% by mass or less, based on 100% by mass of the non-volatile components of the resin composition.

12. A resin composition according to claim 1, in which the mass ratio of component (A) to component (C) (content of component (A)) / (content of component (C)) is 0.01 or more and 1.5 or less.

13. The resin composition according to claim 1, further comprising (D) a polymerization initiator.

14. The resin composition of claim 1, further comprising (E) a polymeric resin.

15. The resin composition according to claim 1, which is used to form an insulating layer of a circuit board.

16. A cured product of the resin composition according to any one of claims 1 to 15.

17. A resin sheet comprising a support and a resin composition layer formed on the support, wherein the resin composition layer contains the resin composition according to any one of claims 1 to 15.

18. A circuit board comprising a cured product of the resin composition according to any one of claims 1 to 15.

19. A semiconductor device comprising the circuit board according to claim 18.

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