Resin composition, prepreg, resin film, laminate, printed wiring board, and semiconductor package

Abstract

The present invention provides: a resin composition which exhibits low transmission loss and excellent flame retardancy, and can improve the appearance of a laminate; and the like. Specifically, the resin composition is as follows. The resin composition contains (A) a thermosetting resin, (B) a polymer that has a hydrocarbon chain or a polyether chain, (X) a phosphorus compound-based flame retardant, and (Y) a flame retardant other than the phosphorus compound-based flame retardant, wherein: in cases where the (X) component does not contain (X1) a filler flame retardant, and the (Y) component does not contain (Y1) a filler flame retardant, or in cases where the (X) component contains (X1) a filler flame retardant or the (Y) component contains (Y1) a filler flame retardant, the total content of the (X1) filler flame retardant and the (Y1) filler flame retardant is 25 parts by mass or less with respect to 100 parts by mass of the solid content in the resin composition.

Description

Resin compositions, prepregs, resin films, laminates, printed wiring boards, and semiconductor packages

[0001] The present disclosure relates to a resin composition, a prepreg, a resin film, a laminate, a printed wiring board, and a semiconductor package.

[0002] In electronic devices such as mobile communication devices typified by mobile phones, their base station equipment, servers, routers, and other network infrastructure devices, and large-scale computers, the speed and capacity of the signals used are increasing year by year. Accordingly, there is a demand for substrate materials for printed wiring boards mounted on these electronic devices that can reduce the transmission loss of high-frequency signals. In recent years, in addition to the electronic devices mentioned above, new systems that handle high-frequency wireless signals have been put into practical use or are planned for practical use in the fields of intelligent transport systems (ITS) related to automobiles and transportation systems, and indoor short-range communications. Therefore, it is expected that there will be an increasing need for substrate materials with excellent high-frequency characteristics for printed wiring boards used in these fields in the future.

[0003] From the viewpoint of safety, printed wiring boards require high flame retardancy. For printed wiring boards that require extremely low transmission loss, hydrocarbon resins that contribute to low transmission loss, such as polybutadiene and styrene-ethylene-butylene-styrene block copolymer (SEBS), are used (see, for example, Patent Document 1). However, although such hydrocarbon resins are effective in reducing transmission loss, increasing the amount of these resins added tends to deteriorate flame retardancy. Therefore, it has been difficult to achieve both low transmission loss and excellent flame retardancy with resin compositions containing these hydrocarbon resins.

[0004] Japanese Patent Application Laid-Open No. 2004-182851

[0005] Therefore, the present inventors have investigated the possibility of achieving both low transmission loss and excellent flame retardancy in a resin composition containing a hydrocarbon resin by using a specific combination of flame retardants, but have found that low transmission loss and excellent flame retardancy do not necessarily coexist, and furthermore, that the laminate tends to have a poor appearance due to the formation of smears on the surface.

[0006] In view of the above circumstances, the present disclosure aims to provide a resin composition that exhibits low transmission loss and excellent flame retardancy and can improve the appearance of laminates, and also aims to provide prepregs, resin films, laminates, printed wiring boards, and semiconductor packages produced using the resin composition.

[0007] The present inventors have conducted extensive research to achieve the above-mentioned object, and have found that the present disclosure can achieve the above-mentioned object. The present disclosure includes the following embodiments [1] to

[15] . [1] A resin composition containing (A) a thermosetting resin, (B) a polymer having a hydrocarbon chain or a polyether chain, (X) a phosphorus compound-based flame retardant, and (Y) a flame retardant other than the phosphorus compound-based flame retardant, wherein the component (X) does not contain a filler flame retardant (X1), and the component (Y) does not contain a filler flame retardant (Y1), or, when the component (X) contains a filler flame retardant (X1) or the component (Y) contains a filler flame retardant (Y1), the total content of the filler flame retardant (X1) and the filler flame retardant (Y1) is 25 parts by mass or less per 100 parts by mass of the solid content of the resin composition. [2] The resin composition according to [1] above, wherein the (X) component contains a compatible flame retardant (X2). [3] The resin composition according to [1] or [2] above, wherein the (Y) component contains a compatible flame retardant (Y2). [4] The resin composition according to any one of [1] to [3] above, wherein the (A) component contains at least one selected from the group consisting of epoxy resins, maleimide compounds, phenolic resins, polyimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins. [5] The resin composition according to any one of [1] to [4] above, wherein the (B) component is at least one selected from the group consisting of conjugated diene polymers, styrene-based elastomers, and modified products thereof. [6] The resin composition according to any one of [1] to [5] above, wherein the component (X) comprises at least one selected from the group consisting of (X-i) a phosphate compound, (X-ii) a phosphine oxide compound, (X-iii) a phosphaphenanthrene compound, (X-iv) a metal salt of phosphinic acid, and (X-v) an organic nitrogen-containing phosphorus compound. [7] The resin composition according to any one of [1] to [6] above, wherein the component (X) has two or more phosphorus atoms in one molecule. [8] The resin composition according to any one of [1] to [7] above, wherein the component (Y) is a halogen-based flame retardant.[9] The resin composition according to any one of [1] to [8] above, further comprising (C) an inorganic filler.

[10] The resin composition according to any one of [1] to [9] above, further comprising (D) a curing accelerator.

[11] A prepreg containing the resin composition according to any one of [1] to

[10] above or a semi-cured product of the resin composition.

[12] A resin film containing the resin composition according to any one of [1] to

[10] above or a semi-cured product of the resin composition.

[13] A laminate having one or more selected from the group consisting of a cured product of the resin composition according to any one of [1] to

[10] above, a cured product of the prepreg according to

[11] above, and a cured product of the resin film according to

[12] above, and a metal foil.

[14] A printed wiring board having one or more selected from the group consisting of a cured product of the resin composition according to any one of [1] to

[10] above, a cured product of the prepreg according to

[11] above, a cured product of the resin film according to

[12] above, and a laminate according to

[13] above.

[15] A semiconductor package comprising the printed wiring board according to

[14] above and a semiconductor element.

[0008] According to the present disclosure, it is possible to provide a resin composition that exhibits low transmission loss and excellent flame retardancy and can improve the appearance of a laminate. Furthermore, it is possible to provide a prepreg, a resin film, a laminate, a printed wiring board, and a semiconductor package using the resin composition.

[0009] In the numerical ranges described in this disclosure, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples. Furthermore, the lower and upper limits of a numerical range can be arbitrarily combined with the lower or upper limit of another numerical range. In the expression "AA to BB," the two extreme values ​​AA and BB are included as the lower and upper limits, respectively, of the numerical range. In this disclosure, for example, the expression "10 or more" means 10 and a value greater than 10, and this also applies when the numerical values ​​differ. Furthermore, for example, the expression "10 or less" means 10 and a value less than 10, and this also applies when the numerical values ​​differ. Furthermore, unless otherwise specified, each component and material exemplified in this disclosure may be used alone or in combination of two or more types. In this disclosure, when multiple substances corresponding to each component (e.g., component (A)) are present in the resin composition, the content of each component in the resin composition refers to the total amount of the multiple substances present in the resin composition, unless otherwise specified.

[0010] In the present disclosure, the term "resin component" is defined as all components of the solid content constituting the resin composition, excluding inorganic compounds such as (C) inorganic filler, which will be described later. In the present disclosure, the term "solid content" refers to components in the resin composition other than the organic solvent, which will be described later, and components that are liquid at room temperature around 25°C are also considered to be solid content. The expression "containing XX" described in the present disclosure means both containing XX in a reacted state when XX is reactive, and simply containing XX. The present disclosure and the present embodiment also include any combination of the items described in the present disclosure.

[0011] [Resin Composition] This embodiment relates to the following resin composition: A resin composition containing (A) a thermosetting resin, (B) a polymer having a hydrocarbon chain or a polyether chain, (X) a phosphorus compound-based flame retardant, and (Y) a flame retardant other than the phosphorus compound-based flame retardant, wherein the (X) component does not contain the (X1) filler flame retardant and the (Y) component does not contain the (Y1) filler flame retardant, or, when the (X) component contains the (X1) filler flame retardant or the (Y) component contains the (Y1) filler flame retardant, the total content of the (X1) filler flame retardant and the (Y1) filler flame retardant is 25 parts by mass or less per 100 parts by mass of the solid content in the resin composition. Each component contained in the resin composition of this embodiment will be described in detail below.

[0012] ((A) Thermosetting Resin) Examples of the component (A) include epoxy resins, maleimide compounds, phenolic resins, polyimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins. Among these, the component (A) preferably contains at least one selected from the group consisting of epoxy resins, maleimide compounds, phenolic resins, polyimide resins, cyanate resins, and isocyanate resins, more preferably contains at least one selected from the group consisting of epoxy resins and maleimide compounds, and even more preferably contains a maleimide compound from the viewpoint of low thermal expansion, etc. As the component (A), one type may be used alone, or two or more types may be used in combination.

[0013] The epoxy resin is preferably an epoxy resin having two or more epoxy groups in one molecule. Here, epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, etc. Among these, glycidyl ether type epoxy resins are preferred.

[0004] Epoxy resins are classified into various epoxy resins depending on the difference in their main skeletons, and each of the above types of epoxy resins can be further classified into bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; alicyclic epoxy resins such as dicyclopentadiene-type epoxy resins; aliphatic chain epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, bisphenol F novolac-type epoxy resins, phenol aralkyl novolac-type epoxy resins, and biphenyl aralkyl novolac-type epoxy resins; stilbene-type epoxy resins; naphthalene-skeleton-containing epoxy resins such as naphthol novolac-type epoxy resins and naphthol aralkyl-type epoxy resins; biphenyl-type epoxy resins; xylylene-type epoxy resins; and dihydroanthracene-type epoxy resins.

[0014] The maleimide compound preferably includes at least one selected from the group consisting of maleimide compounds having one or more N-substituted maleimide groups and derivatives thereof. The maleimide compound having one or more N-substituted maleimide groups is preferably a maleimide compound having two or more N-substituted maleimide groups, more preferably a maleimide compound having 2 to 10 N-substituted maleimide groups, even more preferably a maleimide compound having 2 to 5 N-substituted maleimide groups, and particularly preferably a maleimide compound having two N-substituted maleimide groups. Furthermore, the maleimide compound having two or more N-substituted maleimide groups is preferably a compound in which nitrogen atoms of the maleimide groups are bonded to each other via an organic group.

[0015] The maleimide compound having one or more N-substituted maleimide groups is not particularly limited, and examples thereof include aromatic maleimide compounds preferably having one N-substituted maleimide group bonded to an aromatic ring, such as N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, and N-benzylmaleimide; 4,4'-diphenylmethane bismaleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3 aromatic bismaleimide compounds preferably having two N-substituted maleimide groups bonded to an aromatic ring, such as 1,2-dimethyl-2,3-dimethyl-2,4-dimethyl-2,5-dimethyl-2,6-dimethyl-2,7-dimethyl-2,8-dimethyl-2,9-dimethyl-2,9-dimethyl-2,9-dimethyl-2,10-dimethyl-2,11-dimethyl-2,12-dimethyl-2,13-dimethyl-2,14-dimethyl-2,15-dimethyl-2,16-dimethyl-2,17-dimethyl-2,18-dimethyl-2,19-dimethyl-2,20-dimethyl-2,21-dimethyl-2,22-dimethyl-2,30-dimethyl-2,31-dimethyl-2,32-dimethyl-2,40-dimethyl-2,41-dimethyl-2,52-dimethyl-2,53-dimethyl-2,54-dimethyl-2,60-dimethyl-2,71-dimethyl-2,72-dimethyl-2,71-dimethyl-2,8-dimethyl-2,9-dimethyl-2,10-dimethyl-2,11-dimethyl-2,12-dimethyl-2,13-dimethyl-2,14-dimethyl-2,15-dimethyl-2,16-dimethyl-2,17-dimethyl-2,18-dimethyl-2,19 ... Among these, from the viewpoints of compatibility with other resins, adhesion to conductors, heat resistance, low thermal expansion, mechanical properties, and low transmission loss, aromatic bismaleimide compounds having two N-substituted maleimide groups bonded to an aromatic ring are preferred, and aromatic polymaleimide compounds having three or more N-substituted maleimide groups bonded to an aromatic ring are more preferred, with biphenylaralkyl maleimides and indane ring-containing aromatic bismaleimides being even more preferred. Here, in the present disclosure, an indane ring refers to a fused bicyclic structure of an aromatic six-membered ring and a saturated aliphatic five-membered ring. The indane ring-containing aromatic bismaleimide preferably has a divalent group represented by the following general formula (a1-1):

[0016] (In the formula, Rａ１ represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxyl group, or a mercapto group, and n1 is an integer of 0 to 3. ａ２ ~R ａ４ are each independently an alkyl group having 1 to 10 carbon atoms. * represents a bonding site.

[0017] As the indan ring-containing aromatic bismaleimide containing the divalent group represented by general formula (a1-1), one represented by the following general formula (a1-2) is preferred, from the viewpoints of low transmission loss, adhesion to a conductor, heat resistance, and ease of production:

[0018] (In the formula, R ａ１ ~R ａ４ and n1 are the same as those in the general formula (a1-1). ａ５ are each independently an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, or a mercapto group; each n2 is independently an integer of 0 to 4, and n3 is a number of 0.95 to 10.0.

[0019] From the viewpoints of low transmission loss, adhesion to conductors, solvent solubility, and ease of production, the indan ring-containing aromatic bismaleimide represented by general formula (a1-2) is more preferably one represented by the following general formula (a1-3) or one represented by the following general formula (a1-4):

[0020] (In the formula, R ａ１ ~R ａ５ and n1 and n3 are the same as those in the general formula (a1-2).

[0021] (In the formula, R ａ１ ~R ａ４and n1 and n3 are the same as those in the general formula (a1-2).

[0022] There is no particular limitation on the method for producing the indan ring-containing aromatic bismaleimide, and it may be produced by a known method.

[0023] Examples of the "derivative" of the maleimide compound include an addition reaction product of a maleimide compound having one or more (preferably two or more) N-substituted maleimide groups and one or more amine compounds selected from the group consisting of monoamine compounds, diamine compounds, etc. Examples of the monoamine compound include monoamine compounds having an acidic substituent, such as o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, and 3,5-dicarboxyaniline. Examples of the diamine compound include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 2,2'-bis(4,4'-diaminodiphenyl)propane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylethane, 3,3'-diethyl-4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl diamine compounds having an aromatic hydrocarbon group, such as phenyl thioether, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dibromo-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetrachloro-4,4'-diaminodiphenylmethane, and 2,2',6,6'-tetrabromo-4,4'-diaminodiphenylmethane; and siloxane diamines.

[0024] (Content of Component (A)) The content of the thermosetting resin (A) in the resin composition of the present embodiment is not particularly limited, but from the viewpoints of heat resistance, moldability, and the like, it is preferably 3 to 95 parts by mass, more preferably 5 to 80 parts by mass, even more preferably 5 to 60 parts by mass, particularly preferably 5 to 45 parts by mass, and most preferably 7 to 30 parts by mass, relative to 100 parts by mass of the solid content in the resin composition.

[0025] ((B) Polymer Having a Hydrocarbon Chain or a Polyether Chain) From the viewpoint of reducing transmission loss, the resin composition of this embodiment contains a polymer having a hydrocarbon chain or a polyether chain as component (B). The polymer having a hydrocarbon chain or a polyether chain is preferably a polymer having a hydrocarbon chain or a polyether chain in its main chain. In the present disclosure, the term "main chain" refers to the relatively longest bonded chain in a polymer molecule, and the term "side chain" refers to an atomic group branching off from the main chain. Furthermore, the term "hydrocarbon chain" refers to a structure in which carbon atoms bonded to hydrogen atoms are linked in a chain. Furthermore, the term "polyether chain" refers to a structure in which units containing polyether bonds are linked in a chain. One type of component (B) may be used alone, or two or more types may be used in combination.

[0026] The polymer having a hydrocarbon chain is preferably at least one selected from the group consisting of a conjugated diene polymer, a styrene-based elastomer, and modified products thereof. Hereinafter, modified products of conjugated diene polymers may be referred to as modified conjugated diene polymers. As modified conjugated diene polymers, conjugated diene polymers modified with the maleimide compound described above are preferred, and conjugated diene polymers modified with the maleimide compound having two or more N-substituted maleimide groups are more preferred. Furthermore, examples of polymers having a polyether chain include polyphenylene ether and modified products of polyphenylene ether. Among these, from the viewpoints of compatibility with other resins, low transmission loss, and heat resistance, polymers having a hydrocarbon chain are preferred as component (B), and conjugated diene polymers and styrene-based elastomers are more preferred. Furthermore, from the viewpoints of compatibility with other resins, low transmission loss, and heat resistance, conjugated diene polymers having vinyl groups in their side chains are preferred as conjugated diene polymers. Hereinafter, the conjugated diene polymer having a vinyl group in its side chain may be referred to as a “(B1) conjugated diene polymer” or “(B1) component,” and the styrene-based elastomer may be referred to as a “(B2) styrene-based elastomer” or “(B2) component.” The (B1) component and the (B2) component will be described in order.

[0027] ((B1) Conjugated Diene Polymer) As described above, the component (B1) is a conjugated diene polymer having a vinyl group in the side chain. By using the component (B1) as the component (B), the dielectric loss tangent (Df) of the cured product of the obtained resin composition tends to be further improved, resulting in lower transmission loss. One type of the component (B1) may be used alone, or two or more types may be used in combination.

[0028] The component (B1) is preferably a conjugated diene polymer having multiple vinyl groups in its side chains. The number of vinyl groups in one molecule of the component (B1) is not particularly limited, but from the viewpoints of low transmission loss and heat resistance, it is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more.

[0029] In the present disclosure, a conjugated diene polymer refers to a polymer of a conjugated diene compound. Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. The conjugated diene polymer may be a polymer of one type of conjugated diene compound, or a polymer of two or more types of conjugated diene compounds. Furthermore, the conjugated diene polymer may be a copolymer of one or more types of conjugated diene compounds and one or more types of monomers other than the conjugated diene compounds. In this case, the polymerization mode is not particularly limited and may be random polymerization, block polymerization, or graft polymerization.

[0030] Specific examples of component (B1) include polybutadiene having a 1,2-vinyl group, butadiene-styrene copolymer having a 1,2-vinyl group, and polyisoprene having a 1,2-vinyl group. Among these, from the viewpoints of low transmission loss and heat resistance, polybutadiene having a 1,2-vinyl group and butadiene-styrene copolymer having a 1,2-vinyl group are preferred, and polybutadiene having a 1,2-vinyl group is more preferred. Furthermore, as polybutadiene having a 1,2-vinyl group, butadiene homopolymer having a 1,2-vinyl group is preferred. The butadiene-derived 1,2-vinyl group contained in component (B1) is a vinyl group contained in a butadiene-derived structural unit represented by the following formula (b1-1):

[0031]

[0032] When component (B1) is a polybutadiene having a 1,2-vinyl group, the content of structural units having a 1,2-vinyl group relative to all structural units derived from butadiene constituting the polybutadiene [hereinafter, sometimes referred to as the "vinyl group content"] is not particularly limited, but from the viewpoints of compatibility with other resins, low transmission loss, low thermal expansion, and heat resistance, it is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, particularly preferably 80 mol% or more, and most preferably 85 mol% or more. There is no particular upper limit to the vinyl group content, and it may be 100 mol% or less, 97 mol% or less, or even 95 mol% or less. As the structural unit having a 1,2-vinyl group, a butadiene-derived structural unit represented by the above formula (b1-1) is preferred. From the same viewpoint, the polybutadiene having a 1,2-vinyl group is preferably a 1,2-polybutadiene homopolymer.

[0033] There are no particular limitations on the number average molecular weight of component (B1), but from the viewpoints of compatibility with other resins, low transmission loss, low thermal expansion, and heat resistance, it is preferably 400 to 4,000, more preferably 500 to 3,000, even more preferably 600 to 2,000, and particularly preferably 700 to 1,500.

[0034] ((B2) Styrene-based elastomer) The component (B2) is not particularly limited as long as it is an elastomer having a structural unit derived from a styrene-based compound. When the component (B) contains the component (B2), the dielectric loss tangent (Df) of the cured product of the obtained resin composition tends to be further improved, resulting in low transmission loss. The component (B2) may be used alone or in combination of two or more types.

[0035] The component (B2) is preferably a compound having a structural unit derived from styrene, represented by the following general formula (b2-1).

[0036] (In the formula, R ｂ５ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ｂ６ is an alkyl group having 1 to 5 carbon atoms; and k is an integer of 0 to 5.

[0037] Rｂ５ and R ｂ６ Examples of the alkyl group having 1 to 5 carbon atoms represented by include a methyl group, an ethyl group, and an n-propyl group. Among these, an alkyl group having 1 to 3 carbon atoms is preferred, an alkyl group having 1 or 2 carbon atoms is more preferred, and a methyl group is even more preferred. k is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0038] Examples of structural units other than those derived from styrene compounds contained in component (B2) include structural units derived from butadiene, structural units derived from isoprene, structural units derived from maleic acid, and structural units derived from maleic anhydride. The above-mentioned structural units derived from butadiene and structural units derived from isoprene may be hydrogenated. When hydrogenated, the butadiene-derived structural units become structural units in which ethylene units and butylene units are mixed, and the isoprene-derived structural units become structural units in which ethylene units and propylene units are mixed.

[0039] From the viewpoints of low transmission loss, adhesion to the conductor, heat resistance, and low thermal expansion, component (B2) is preferably at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymers (SEBS and SBBS), hydrogenated styrene-isoprene-styrene block copolymers (SEPS), and styrene-maleic anhydride copolymers (SMA), more preferably at least one selected from the group consisting of SEBS and SEPS, and even more preferably SEBS. Here, SEBS is a styrene-butadiene-styrene block copolymer (SBS) in which the butadiene units have been hydrogenated, and is named after the initials of styrene-ethylene-butylene-styrene, while SBBS is a styrene-butadiene-styrene block copolymer (SBS) in which the 1,2-bond units in the butadiene units have been selectively hydrogenated, and is named after the initials of styrene-(1,4-butadiene)-butylene-styrene. SEPS is a styrene-isoprene-styrene block copolymer (SIS) in which the isoprene units have been hydrogenated, and is named after the initials of styrene-ethylene-propylene-styrene.

[0040] In the SEBS, the content of styrene-derived structural units [hereinafter, may be referred to as "styrene content"] is not particularly limited, but from the viewpoints of low thermal expansion, low transmission loss, adhesion to the conductor, and heat resistance, it is preferably 5 to 80 mass%, more preferably 10 to 75 mass%, even more preferably 15 to 70 mass%, still more preferably 20 to 50 mass%, and particularly preferably 25 to 45 mass%.

[0041] Examples of commercially available SEBS products include the Tuftec H series and M series manufactured by Asahi Kasei Corporation, the Septon series manufactured by Kuraray Co., Ltd., and the Kraton G Polymer series manufactured by Kraton Polymer Japan Co., Ltd.

[0042] The weight average molecular weight (Mw) of component (B2) is not particularly limited, but is preferably 12,000 to 1,000,000, more preferably 30,000 to 500,000, even more preferably 50,000 to 200,000, particularly preferably 70,000 to 150,000, and most preferably 90,000 to 130,000. The weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) in terms of polystyrene, and more specifically, is a value measured by the measurement method described in the Examples.

[0043] [Content Ratio of Conjugated Diene Polymer (B1) and Styrene-Based Elastomer (B2)] In the resin composition of the present embodiment, when the components (B1) and (B2) are used in combination, the content ratio of the components (B1) to the components (B2) [(B1) / (B2)] is not particularly limited, but from the viewpoints of moldability, compatibility with other resins, and low transmission loss, is preferably 2 / 98 to 70 / 30, more preferably 5 / 95 to 60 / 40, even more preferably 10 / 90 to 50 / 50, and particularly preferably 20 / 80 to 40 / 60 by mass.

[0044] (Content of Component (B)) The content of component (B) in the resin composition of this embodiment is not particularly limited, but is preferably 3 to 35 parts by mass, more preferably 5 to 30 parts by mass, even more preferably 10 to 30 parts by mass, particularly preferably 15 to 30 parts by mass, and most preferably 15 to 25 parts by mass, per 100 parts by mass of the solid content in the resin composition. If the content of component (B) is 3 parts by mass or more per 100 parts by mass of the solid content in the resin composition, there is a tendency for the transmission loss to be reduced, and if it is 35 parts by mass or less, there is a tendency for the heat resistance and flame retardancy to be maintained at a good level.

[0045] (X) Phosphorus Compound-Based Flame Retardant The resin composition of this embodiment contains a phosphorus compound-based flame retardant as component (X). Phosphorus compound-based flame retardants have a flame retardant mechanism in which a phosphoric acid layer formed by decomposition blocks oxygen, and furthermore, they carbonize organic matter through a dehydration action to form a film called char on the surface of the burned material, thereby blocking oxygen. Examples of phosphorus compound-based flame retardants include phosphorus oxide compounds. Here, the term "phosphorus oxide compound" refers to a compound having the following phosphorus oxide structure: (* indicates the bond position.)

[0046] The aromatic ring contained in component (X) is preferably an aromatic ring having 6 to 18 ring carbon atoms, and examples include a benzene ring, a naphthalene ring, and an anthracene ring. A benzene ring is preferred as the aromatic ring. The aromatic ring may have a substituent, or may be unsubstituted. Examples of the substituent that the aromatic ring may have include alkyl groups having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group; and alkoxy groups, such as a methoxy group, an ethoxy group, and an isopropoxy group. The substituent is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group.

[0047] Component (X) preferably has two or more aromatic rings per molecule, more preferably 2 to 10, even more preferably 2 to 6, particularly preferably 4 to 6, and most preferably 5. When component (X) has two or more aromatic rings per molecule, the aromatic rings may be the same or different, but are preferably the same. In component (X), the aromatic ring may be directly bonded to the phosphorus atom, may be bonded to the phosphorus atom via an oxygen atom, or may be bonded to the phosphorus atom via an alkylene group such as a methylene group. From the viewpoints of low thermal expansion, high elasticity, and low transmission loss, component (X) preferably has two or more phosphorus atoms per molecule, more preferably 2 to 4 phosphorus atoms per molecule, and even more preferably 2 phosphorus atoms per molecule.

[0048] The component (X) is not particularly limited, but from the viewpoint of low thermal expansion, high elasticity, and low transmission loss, it preferably contains at least one selected from the group consisting of (X-i) phosphate compounds, (X-ii) phosphine oxide compounds, (X-iii) phosphaphenanthrene compounds, (X-iv) metal salts of phosphinic acid, and (X-v) organic nitrogen-containing phosphorus compounds, more preferably contains at least one selected from the group consisting of (X-i) phosphate compounds, (X-ii) phosphine oxide compounds, and (X-iv) metal salts of phosphinic acid, and even more preferably contains at least one selected from the group consisting of (X-ii) phosphine oxide compounds and (X-iv) metal salts of phosphinic acid. Components (X-i) to (X-v) will be described in detail below in order.

[0049] ((X-i) Phosphate Compound) One type of phosphate compound may be used alone, or two or more types may be used in combination. Commercially available phosphate compounds can be used. The component (X-i) preferably has two or more phosphate groups in the molecule, and more preferably has two phosphate groups in the molecule. Here, the phosphate group is a group represented by the following formula: (* indicates the bond position.)

[0050] A phosphate compound having two or more phosphate groups in the molecule preferably has a linking group that links the two or more phosphate groups. The linking group is not particularly limited, but examples include a phenylene group, a xylylene group, a biphenylene group, a naphthylene group, a methylene group, and an ethylene group. From the viewpoint of achieving a high melting point of component (X-i), the linking group preferably contains at least one selected from the group consisting of a phenylene group, a xylylene group, a biphenylene group, and a naphthylene group, and more preferably contains a phenylene group.

[0051] From the viewpoints of low thermal expansion, high elasticity, and low transmission loss, the oxygen atom of the phosphate group may be substituted on the aromatic ring. From the viewpoints of improving the adhesive strength to the metal foil and the soldering heat resistance while maintaining good low thermal expansion, the component (X-i) is preferably a compound represented by the following general formula (X-1):

[0052] (In the formula, R ｘ１ ~R ｘ４ each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms. ｘ１ represents a divalent group represented by the following general formula (X-2) or a divalent fused polycyclic aromatic hydrocarbon group: ｘ１ ~n ｘ４ each independently represents an integer of 0 to 5, ｘ５ represents an integer from 0 to 5.)

[0053] (In the formula, R ｘ５ and R ｘ６ each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. ｘ２ represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, —O—, —S—, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. ｘ６ and n ｘ７ Each independently represents an integer of 0 to 4. ｘ８ represents an integer of 0 to 3.)

[0054] R in the general formula (X-1) ｘ１ ~R ｘ４Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by n include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, etc. As the aliphatic hydrocarbon group, an aliphatic hydrocarbon group having 1 to 3 carbon atoms is preferred, an alkyl group having 1 to 3 carbon atoms is more preferred, and a methyl group is even more preferred. ｘ１ ~n ｘ４ represents an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 2, and even more preferably 2. ｘ１ ~n ｘ４ is an integer of 2 or more, a plurality of R ｘ１ Comrade, R ｘ２ Comrade, R ｘ３ Comrades or R ｘ４ may be the same or different. ｘ５ represents an integer of 0 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1. ｘ５ is an integer of 2 or more, a plurality of Z ｘ１ n and multiple n ｘ４ They may be the same or different from each other.

[0055] The definitions of each group in the general formula (X-2) are as described above. ｘ５ and R ｘ６ The aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ｘ１ ~R ｘ４ The aliphatic hydrocarbon groups having 1 to 5 carbon atoms are the same as those shown by R ｘ５ and R ｘ６ Examples of the halogen atom represented by Z include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. ｘ２ Examples of the alkylene group having 1 to 5 carbon atoms represented by Z include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, and a 1,5-pentamethylene group. ｘ２ Examples of the alkylidene group having 2 to 5 carbon atoms represented by include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, and an isopentylidene group.ｘ６ and n ｘ７ are each independently an integer of 0 to 4, preferably 0 or 1, and more preferably 0. ｘ８ is an integer of 0 to 3, preferably 0 or 1, and more preferably 0. The general formula (X-2) is preferably the following general formula (X-2-1). (In the formula, the definition of each group is the same as the definition of each group in general formula (X-2).)

[0056] Z in the general formula (X-1) ｘ１ Examples of the divalent fused polycyclic aromatic hydrocarbon group represented by the formula (I) include divalent groups obtained by removing two hydrogen atoms from a fused polycyclic aromatic hydrocarbon such as naphthalene, anthracene, or pyrene. The fused polycyclic aromatic hydrocarbon group may be substituted or unsubstituted with a substituent. Examples of the substituent on the fused polycyclic aromatic hydrocarbon group include aliphatic hydrocarbon groups having 1 to 5 carbon atoms, such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, or n-pentyl group; and halogen atoms, such as a fluorine atom, chlorine atom, bromine atom, or iodine atom.

[0057] Specific examples of the phosphate compound (X-i) include 1,3-phenylene-bis(di-2,6-dimethylphenyl phosphate), 1,3-phenylene-bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), 1,4-phenylene-bis(di-2,6-dimethylphenyl phosphate), 4,4'-biphenylene-bis(di-2,6-dimethylphenyl phosphate), bisphenol A polyphenyl phosphate, 4,4'-biphenol-polycresyl phosphate, bisphenol A polycresyl phosphate, 4,4'-biphenol-poly(2,6-xylenyl phosphate), bisphenol A poly(2,6-xylenyl phosphate), etc. Note that the term "poly" in the specific examples of the phosphate compound refers to a compound having two or more structural units composed of a structure derived from a divalent phenol compound and a structure derived from phosphoric acid that constitute the phosphate compound, and may also refer to a compound in which the average number of structural units exceeds 1 due to the inclusion of the compound. Here, the "structural unit" refers to the structural unit in the brackets in the general formula (X-1), for example.

[0058] (X-ii) Phosphine oxide compound) One phosphine oxide compound may be used alone, or two or more phosphine oxide compounds may be used in combination. Commercially available phosphine oxide compounds can be used. The component (X-ii) preferably has two or more diphenylphosphine oxide groups in the molecule, and more preferably has two diphenylphosphine oxide groups in the molecule. Here, the diphenylphosphine oxide group is a group represented by the following formula: (* indicates the bond position.)

[0059] From the viewpoint of achieving low transmission loss, the melting point of component (X-ii) is preferably 280°C or higher, and more preferably 310°C or higher. From the viewpoint of the decomposition temperature of organic substances, the melting point of the phosphine oxide compound is limited to approximately 450°C. For this reason, the melting point of component (X-ii) is preferably 280 to 450°C, and more preferably 310 to 450°C. The melting point can be measured using a thermogravimetric / differential thermal analyzer (TG / DTA).

[0060] A phosphine oxide compound having two or more diphenylphosphine oxide groups in the molecule preferably has a linking group that links the two or more diphenylphosphine oxide groups. The linking group is not particularly limited, but examples include a phenylene group, a xylylene group, a biphenylene group, a naphthylene group, a methylene group, and an ethylene group. From the viewpoint of achieving a high melting point of component (X-ii), the linking group preferably contains at least one selected from the group consisting of a phenylene group, a xylylene group, a biphenylene group, and a naphthylene group, and more preferably contains a phenylene group.

[0061] Specific examples of the component (X-ii) include the following compounds:

[0062] ((X-iii) Phosphaphenanthrene Compound) One type of phosphaphenanthrene compound may be used alone, or two or more types may be used in combination. Commercially available phosphaphenanthrene compounds can be used. Examples of the component (X-iii) include compounds represented by the following formula (X-3). (In the formula, R ｘ１０ and R ｘ１１ are each independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. b and c are each independently an integer of 0 to 4. A is a hydrogen atom or a group represented by any one of the following formulas (X-4) to (X-6). (* indicates the bond position.) (* indicates the bond position.) (* indicates the bond position.)

[0063] Examples of the component (X-iii) include 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, 9,10-dihydro-10-(2,5-dihydroxyphenyl)-9-oxa-10-phosphaphenanthrene 10-oxide, and the like.

[0064] (X-iv) Metal Salt of Phosphinic Acid As the component (X-iv), a metal salt of dialkylphosphinic acid is preferred. Here, examples of the "metal salt" include lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, titanium salt, and zinc salt. Of these, the aluminum salt is preferred as the metal salt. Furthermore, examples of the alkyl group possessed by the dialkylphosphinic acid include alkyl groups having 1 to 10 carbon atoms. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferred, an alkyl group having 1 to 4 carbon atoms is more preferred, and an ethyl group is even more preferred.

[0065] ((X-v) Organic Nitrogen-Containing Phosphorus Compound) The component (X-v) may be a phosphazene compound. The phosphazene compound is preferably one having a structural unit represented by the following general formula (X-7).

[0066] (In the formula, R ｘ１２ and R ｘ１３ each independently represents an organic group having 1 to 20 carbon atoms.

[0067] R in the above general formula (X-7) ｘ１２ and R ｘ１３ The organic group having 1 to 20 carbon atoms represented by the formula (I) includes an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0068] R ｘ１２ and R ｘ１３Examples of the aliphatic hydrocarbon group having 1 to 20 carbon atoms that can be mentioned as the organic group having 1 to 20 carbon atoms represented by the formula (I) include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and an alkynyl group having 2 to 20 carbon atoms. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, a 2-ethylhexyl group, and a cyclohexyl group. Examples of the alkenyl group having 2 to 20 carbon atoms include a vinyl group, a propenyl group, and a butenyl group. Examples of the alkynyl group having 2 to 20 carbon atoms include a 2-propynyl group and a 3-butynyl group. The aliphatic hydrocarbon group having 1 to 20 carbon atoms may or may not have a substituent. Examples of the substituent include a hydroxyl group, a carboxyl group, a halogen atom, an aromatic hydrocarbon group, an acyl group, an alkoxy group, a group formed by linking these substituents, etc. When the aliphatic hydrocarbon group has a substituent, the number of carbon atoms mentioned above includes the number of carbon atoms of the substituent.

[0069] R ｘ１２ and R ｘ１３ The number of carbon atoms in the aromatic hydrocarbon group having 6 to 20 carbon atoms, which is exemplified as the organic group having 1 to 20 carbon atoms represented by the formula (I), is preferably 6 to 15, and more preferably 6 to 10. Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and an anthranyl group. The aromatic hydrocarbon group having 6 to 20 carbon atoms may have a substituent, or may not have a substituent. Examples of the substituent include a hydroxyl group, a carboxy group, a halogen atom, an aliphatic hydrocarbon group, an acyl group, an alkoxy group, a cyano group, and groups in which these substituents are linked. A cyano group is preferred as the substituent. When the aromatic hydrocarbon group has a substituent, the number of carbon atoms in the above formula includes the number of carbon atoms of the substituent. Among these, R ｘ１２ and R ｘ１３ From the viewpoint of flame retardancy, the organic group having 1 to 20 carbon atoms represented by is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably an unsubstituted phenyl group or a phenyl group having a substituent, and even more preferably an unsubstituted phenyl group or a cyanophenyl group.

[0070] The phosphazene compound may be a chain phosphazene compound or a cyclic phosphazene compound, but is preferably a cyclic phosphazene compound. As the cyclic phosphazene compound, a phosphazene compound represented by the following general formula (X-8) is preferred, and a phosphazene compound represented by the following general formula (X-9) is more preferred.

[0071] (In the formula, Ar ｘ１ and Ar ｘ２ Each of n independently represents an aromatic hydrocarbon group having 6 to 20 carbon atoms. ｘ９ represents an integer from 3 to 20.) (In the formula, Ar ｘ３ ~Ar ｘ８ each independently represents an aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0072] Ar in the above general formula (X-8) ｘ１ and Ar ｘ２ and Ar in the general formula (X-9). ｘ３ ~Ar ｘ８ The aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R in the above general formula (X-7) is explained below. ｘ１２ and R ｘ１３ The same applies to the aromatic hydrocarbon group having 6 to 20 carbon atoms as defined above. ｘ９ represents an integer of 3 to 20, preferably an integer of 3 to 10, more preferably an integer of 3 to 5, and even more preferably 3.

[0073] (Y) Flame retardant other than the phosphorus compound-based flame retardant) The resin composition of this embodiment contains a flame retardant other than the phosphorus compound-based flame retardant as component (Y). The flame retardant other than the phosphorus compound-based flame retardant is preferably a flame retardant having a flame retardant mechanism different from that of the phosphorus compound-based flame retardant. Here, "having a flame retardant mechanism different from that of the phosphorus compound-based flame retardant" means that the flame retardant mechanism is not the same as that of the phosphorus compound-based flame retardant. The flame retardant mechanism different from that of the phosphorus compound-based flame retardant is not particularly limited, but examples include a flame retardant mechanism in which active OH radicals are stabilized by radical trapping, thereby suppressing combustion. A halogen-based flame retardant is preferred as a flame retardant having a flame retardant mechanism different from that of the phosphorus compound-based flame retardant. It is believed that the resin composition of this embodiment contains both the component (X) and the halogen-based flame retardant, which generates phosphorus halide and oxyhalide, which exhibit excellent radical trapping effects, making it easier to achieve a synergistic flame retardant effect. In this embodiment, from the perspective of the flame retardant mechanism, compounds containing both phosphorus and halogen are classified as component (Y) rather than component (X). The halogen-based flame retardant may be a low-molecular-weight compound or a high-molecular-weight compound. The molecular weight of the low-molecular-weight compound is not particularly limited, but is preferably 1,500 or less, more preferably 200 to 1,500, even more preferably 500 to 1,300, even more preferably 700 to 1,200, particularly preferably 800 to 1,100, and most preferably 900 to 1,100. The molecular weight of the high-molecular-weight compound is not particularly limited, but is preferably greater than 1,500, more preferably greater than 1,500 to 30,000, even more preferably 2,000 to 20,000, and particularly preferably 2,000 to 15,000.

[0074] Examples of halogen-based flame retardants include chlorine compounds and bromine compounds. Among these, bromine compounds are preferred as halogen-based flame retardants. Examples of chlorine compounds include chain aliphatic chlorine compounds and cyclic aliphatic chlorine compounds. Here, the chain aliphatic chlorine compound is a compound having a moiety where a chlorine atom is directly bonded to a chain aliphatic hydrocarbon group, and the cyclic aliphatic chlorine compound is a compound having a moiety where a chlorine atom is directly bonded to a cyclic aliphatic hydrocarbon group. Examples of bromine compounds include chain aliphatic bromine compounds, cyclic aliphatic bromine compounds, and aromatic bromine compounds. Here, the chain aliphatic chlorine compound is a compound having a moiety where a bromine atom is directly bonded to a chain aliphatic hydrocarbon group, and the cyclic aliphatic chlorine compound is a compound having a moiety where a bromine atom is directly bonded to a cyclic aliphatic hydrocarbon group. Furthermore, the aromatic bromine compound is a compound having a moiety where a bromine atom is bonded to an aromatic ring, but does not include compounds having a moiety where a bromine atom is also bonded to an aliphatic hydrocarbon group. Among these, aromatic bromine compounds are preferred as the bromine compounds from the viewpoints of low thermal expansion, high elasticity, and low transmission loss. Specific examples of the bromine compounds include the following compounds:

[0075]

[0076]

[0077] (Content of (X) Component and (Y) Component) The contents of the (X) component and the (Y) component in the resin composition of this embodiment are not particularly limited. For example, relative to 100 parts by mass of the solid content in the resin composition, the (X) component is preferably 0.5 to 10 parts by mass and the (Y) component is 0.5 to 20 parts by mass, more preferably 1.0 to 7 parts by mass and 3 to 18 parts by mass, even more preferably 1.0 to 8 parts by mass and 5 to 17 parts by mass, and particularly preferably 1.5 to 6.5 parts by mass and 8 to 16 parts by mass. If the contents of the (X) component and the (Y) component are within the above numerical ranges, the dielectric loss tangent (Df) is reduced, resulting in low transmission loss, a synergistic effect of flame retardancy is obtained, and the appearance of the laminate also tends to be good.

[0078] (Regarding the (X1) filler flame retardant and the (Y1) filler flame retardant) In this embodiment, when the (X) component does not contain the (X1) filler flame retardant and the (Y) component does not contain the (Y1) filler flame retardant, or when the (X) component contains the (X1) filler flame retardant or the (Y) component contains the (Y1) filler flame retardant, the content of the (X1) filler flame retardant and the total content of the (Y1) filler flame retardant are limited to a predetermined amount. In the present disclosure, "filler" refers to a flame retardant that does not dissolve in a resin varnish when an organic solvent is added to a resin composition to prepare a resin varnish. Whether or not a flame retardant dissolves in a resin varnish is determined by visually inspecting the state of the flame retardant when 17 parts by mass of the flame retardant is added to 83 parts by mass of the resin varnish and stirred at 25°C for 30 minutes. If the flame retardant can be confirmed in the resin varnish, it is determined to be a filler flame retardant. The organic solvent is the same as the organic solvent that may be contained in the resin varnish described below. The organic solvent may be, for example, an aromatic hydrocarbon solvent or toluene. Here, the filler flame retardant (Y1) is assumed to be a flame retardant as component (Y), and therefore is different from the filler flame retardant (X1).

[0079] Examples of filler flame retardants (X1) include, but are not limited to, the metal salts of phosphinic acid (X-iv), and more specifically, aluminum tris(diethylphosphinate). For example, 1,3-phenylenebis(di-2,6-xylenylphosphate), which is a powder at 25°C, is soluble in organic solvents (e.g., aromatic hydrocarbon solvents such as toluene) and is therefore compatible with resin varnishes but is not a filler. Similarly, 1,3-phenylenebis(diphenylphosphate), which is a liquid at 25°C, and bisphenol A bis(diphenylphosphate), which is a liquid at 25°C, are also compatible with resin varnishes but are not a filler. Examples of filler flame retardants (Y') include, but are not limited to, ethylenebispentabromobenzene, 1,2-bis(2,4,6-tribromophenoxy)ethane, and the like. For example, tris(tribromophenoxy)triazine, tribromophenol, tetrabromobisphenol A, etc., which are powders at 25° C., are soluble in organic solvents (for example, aromatic hydrocarbon solvents such as toluene) and are not packable.

[0080] (Total Content of Component (X1) and Component (Y1)) In the resin composition of this embodiment, when the component (X) contains the filler flame retardant (X1) or the component (Y) contains the filler flame retardant (Y1), the total content of the filler flame retardant (X1) and the filler flame retardant (Y1) is 25 parts by mass or less per 100 parts by mass of the solid content in the resin composition. By keeping the content of the filler flame retardant within this range, the effect of improving the appearance of the laminate is greatly improved. From the same viewpoint, in the resin composition of this embodiment, the content of the filler flame retardant (X1) and the total content of the filler flame retardant (Y1) are preferably 0 to 20 parts by mass, more preferably 0 to 18 parts by mass, and even more preferably 0 to 15 parts by mass, relative to 100 parts by mass of the solid content in the resin composition, and may be 1 to 25 parts by mass, 3 to 20 parts by mass, 5 to 20 parts by mass, 8 to 20 parts by mass, 10 to 20 parts by mass, 10 to 18 parts by mass, or 10 to 15 parts by mass.

[0081] (Ratio of the Content of the (X1) Component to the Content of the (Y1) Component) When the resin composition of the present embodiment contains both the (X1) filler flame retardant and the (Y1) filler flame retardant, the ratio of the (X1) filler flame retardant to the (Y1) filler flame retardant [(X1) / (Y1)] is not particularly limited, but from the viewpoint of flame retardancy and the balance between low transmission loss and the appearance of the laminate, the mass ratio is preferably 1 / 99 to 45 / 55, more preferably 5 / 95 to 40 / 60, may be 5 / 95 to 35 / 65, may be 10 / 90 to 30 / 70, may be 10 / 90 to 25 / 75, may be 15 / 85 to 50 / 50, may be 20 / 80 to 45 / 55, or may be 25 / 75 to 45 / 55.

[0082] (Compatible Flame Retardant (X2) and Compatible Flame Retardant (Y2)) In terms of the appearance of the laminate, the resin composition of this embodiment may contain the compatible flame retardant (X2), and preferably the compatible flame retardant (X2). In terms of the appearance of the laminate, the resin composition of this embodiment may contain the compatible flame retardant (Y2), and preferably the compatible flame retardant (Y2). In addition, in terms of the appearance of the laminate, the resin composition of this embodiment may contain the compatible flame retardant (Y2), and preferably the compatible flame retardant (Y2). In the present disclosure, "compatible" refers to a flame retardant that dissolves in a resin varnish when an organic solvent is added to a resin composition to form a resin varnish. Whether or not a flame retardant dissolves in a resin varnish is determined by visually inspecting the state of the flame retardant when 17 parts by mass of the flame retardant is added to 83 parts by mass of the resin varnish and stirred at 25°C for 30 minutes. If no flame retardant is observed in the resin varnish, the flame retardant is determined to be compatible. The organic solvent is the same as the organic solvent that may be contained in the resin varnish described below. The organic solvent may be, for example, an aromatic hydrocarbon solvent or toluene. Here, the compatible flame retardant (Y2) is assumed to be a flame retardant as component (Y), and therefore is different from the compatible flame retardant (X2).

[0083] The compatible flame retardant (X2) is not particularly limited, but examples thereof include the phosphate compounds (X-i) and phosphine oxide compounds (X-ii), more specifically, 1,3-phenylene-bis(di-2,6-dimethylphenylphosphate), triphenylphosphine oxide, etc.

[0084] The compatible flame retardant (Y2) is not particularly limited, but examples thereof include the following halogen-based flame retardants.

[0085] (Content of Component (X2) and Content of Component (Y2)) In the resin composition of this embodiment, when the component (X) contains a compatible flame retardant (X2), the content of the component (X2) is not particularly limited, but from the viewpoints of low transmission loss, flame retardancy, and the appearance of the laminate, it is preferably 0.5 to 10 parts by mass, more preferably 1 to 7 parts by mass, and even more preferably 2 to 5 parts by mass, per 100 parts by mass of the solid content in the resin composition. Furthermore, in the resin composition of this embodiment, when the component (Y) contains a compatible flame retardant (Y2), the content of the component (Y2) is not particularly limited, but from the viewpoints of low transmission loss, flame retardancy, and the appearance of the laminate, it is preferably 0.5 to 17 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 13 parts by mass, per 100 parts by mass of the solid content in the resin composition, and may be 2 to 7 parts by mass or 7 to 17 parts by mass.

[0086] ((C) Inorganic Filler) The resin composition of the present embodiment contains an inorganic filler as component (C) [hereinafter, may be referred to as component (C)], which tends to improve low thermal expansion, elastic modulus, heat resistance, and flame retardancy. One type of component (C) may be used alone, or two or more types may be used in combination.

[0087] Examples of component (C) include silica, alumina, titanium oxide, mica, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay (calcined clay, etc.), molybdate compounds such as zinc molybdate, talc, aluminum borate, and silicon carbide. Among these, from the viewpoints of low thermal expansion, elastic modulus, heat resistance, and flame retardancy, silica, alumina, mica, and talc are preferred, silica and alumina are more preferred, and silica is even more preferred. Examples of silica include crushed silica, fumed silica, and fused silica.

[0088] The average particle size of component (C) is not particularly limited, but is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm, even more preferably 0.2 to 1 μm, and particularly preferably 0.3 to 0.8 μm. The shape of component (C) may be spherical, crushed, etc., but is not particularly limited, and spherical is preferred.

[0089] When the resin composition of the present embodiment contains the component (C), the content of the component (C) in the resin composition is not particularly limited, but from the viewpoints of low thermal expansion, elastic modulus, and heat resistance, it is preferably 5 to 70 parts by mass, more preferably 15 to 65 parts by mass, even more preferably 20 to 60 parts by mass, particularly preferably 30 to 55 parts by mass, and most preferably 40 to 55 parts by mass, relative to 100 parts by mass of the solid content in the resin composition.

[0090] When the resin composition of this embodiment contains component (C), a coupling agent may be used to improve the dispersibility of component (C) and its adhesion to the organic component. A silane coupling agent is preferred as the coupling agent. Examples of such silane coupling agents include aminosilane coupling agents, epoxysilane coupling agents, phenylsilane coupling agents, alkylsilane coupling agents, alkenylsilane coupling agents, alkynylsilane coupling agents, and silicone oligomer coupling agents. A single coupling agent may be used alone, or two or more may be used in combination. When a coupling agent is used, the surface treatment of component (C) may be an integral blend treatment method in which the coupling agent is added after blending component (C) into the resin composition, or a method in which component (C) is previously surface-treated with the coupling agent in a dry or wet manner. Among these, a method in which component (C) is previously surface-treated with the coupling agent in a dry or wet manner is preferred from the viewpoint of more effectively exhibiting the characteristics of component (C). In order to improve dispersibility in the resin composition, the component (C) may be dispersed in an organic solvent in advance to form a slurry, and then mixed with the other components.

[0091] ((D) Curing Accelerator) The resin composition of the present embodiment contains a curing accelerator as component (D) [hereinafter, may be referred to as component (D)], which improves curability and tends to improve elastic modulus, low transmission loss, heat resistance, and adhesion to conductors. One type of component (D) may be used alone, or two or more types may be used in combination.

[0092] Examples of component (D) include acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, and tributylamine; imidazole compounds such as methylimidazole and phenylimidazole; isocyanate-masked imidazole compounds such as the addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and α,α'-bis(t-butylperoxy)diisopropylbenzene; and carboxylates of manganese, cobalt, zinc, and the like. Among these, from the viewpoints of heat resistance and storage stability, imidazole compounds, isocyanate-masked imidazole compounds, organic peroxides, and carboxylates are preferred, organic peroxides are more preferred, and α,α'-bis(t-butylperoxy)diisopropylbenzene is even more preferred.

[0093] When the resin composition of this embodiment contains component (D), the content of component (D) is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, even more preferably 0.1 to 6 parts by mass, and particularly preferably 0.2 to 3 parts by mass, per 100 parts by mass of the resin components in the resin composition. When the content of component (D) is at least the above-mentioned lower limit, the elastic modulus, low transmission loss, heat resistance, and adhesion to conductors tend to be improved. Furthermore, when the content of component (D) is at most the above-mentioned upper limit, the storage stability of the resin composition tends to be improved.

[0094] (Other Components) The resin composition of the present embodiment may further contain, as necessary, one or more additives selected from the group consisting of resin materials other than the above components, antioxidants, flame retardants, flame retardant assistants, heat stabilizers, antistatic agents, UV absorbers, pigments, colorants, lubricants, and other additives. Each of these may be used alone, or two or more may be used in combination. The amount of these additives used is not particularly limited, and they may be used as needed within a range that does not inhibit the effects of the present embodiment.

[0095] The resin composition of this embodiment may be dissolved or dispersed in an organic solvent, in the form of a so-called "resin varnish." Hereinafter, a resin composition containing an organic solvent may be referred to as a "resin varnish." Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbon-based solvents such as toluene and xylene; ester-based solvents such as methoxyethyl acetate, ethoxyethyl acetate, butoxyethyl acetate, and ethyl acetate; amide-based solvents such as N-methylpyrrolidone, formamide, N-methylformamide, and N,N-dimethylacetamide; and alcohol-based solvents such as methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monopropyl ether, and dipropylene glycol monopropyl ether. One type of organic solvent may be used alone, or two or more types may be used in combination. The solid content concentration in the resin varnish is preferably from 10 to 70% by mass, more preferably from 20 to 60% by mass, and even more preferably from 35 to 60% by mass.

[0096] [Prepreg] The prepreg of this embodiment is a prepreg containing the resin composition of this embodiment or a semi-cured product of the resin composition. The prepreg of this embodiment contains, for example, the resin composition of this embodiment or a semi-cured product of the resin composition and a sheet-like fiber substrate. The prepreg is formed using the resin composition or resin film of this embodiment and a sheet-like fiber substrate. For example, the prepreg can be obtained by impregnating or coating the sheet-like fiber substrate with the resin composition or resin film of this embodiment, drying, and semi-curing (B-staging) as needed. More specifically, the prepreg of this embodiment can be produced by, for example, semi-curing (B-staging) by heating and drying in a drying oven, typically at a temperature of 80 to 200°C for 1 to 30 minutes. Here, in this disclosure, B-staging refers to achieving a B-stage state as defined in JIS K6900 (1994). The amount of resin composition used can be determined appropriately so that the solids concentration derived from the resin composition in the prepreg after drying is 30 to 90% by mass. By setting the solid content concentration within the above range, better moldability tends to be obtained when the laminate is formed.

[0097] As the sheet-like fiber substrate for the prepreg, known materials used in various laminates for electrical insulating materials can be used. The sheet-like fiber substrate is not particularly limited, but is preferably a sheet-like fiber reinforcement substrate used for the purpose of reinforcing the prepreg. Examples of materials for the sheet-like fiber substrate include inorganic fibers such as E-glass, D-glass, S-glass, and Q-glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. These sheet-like fiber substrates have shapes such as woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. The thickness of the sheet-like fiber substrate is not particularly limited, but a thickness of 0.02 to 0.5 mm can be used, for example. Furthermore, the sheet-like fiber substrate can be surface-treated with a coupling agent or mechanically opened to improve the impregnation of the resin composition, the heat resistance, moisture absorption resistance, and processability when formed into a laminate.

[0098] The following hot melt method or solvent method can be used as a method for impregnating or coating a sheet-like fiber substrate with a resin composition. The hot melt method is a method in which the resin composition does not contain an organic solvent, and (1) the resin composition is first coated on coated paper that has good peelability from the resin composition and then laminated onto the sheet-like fiber substrate, or (2) the resin composition is coated onto the sheet-like fiber substrate using a die coater. On the other hand, the solvent method is a method in which an organic solvent is added to the resin composition, and the sheet-like fiber substrate is immersed in the obtained resin composition to impregnate the resin composition into the sheet-like fiber substrate, and then dried.

[0099] [Resin Film] The resin film of this embodiment is a resin film containing the resin composition of this embodiment or a semi-cured product of the resin composition. The resin film of this embodiment can be produced, for example, by applying a resin composition containing an organic solvent, i.e., a resin varnish, to a support, and then heating and drying to semi-cure (B-stage) the film as needed. Examples of the support include polyolefin films such as polyethylene, polypropylene, and polyvinyl chloride; polyester films such as polyethylene terephthalate (hereinafter also referred to as "PET") and polyethylene naphthalate; and various plastic films such as polycarbonate and polyimide films. Metal foils such as copper foil and aluminum foil, and release paper may also be used as the support. The support may be subjected to a surface treatment such as a matte finish or a corona treatment. The support may also be subjected to a release treatment using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, or the like. The thickness of the support is not particularly limited, but is preferably 10 to 150 μm, and more preferably 25 to 50 μm.

[0100] The method for applying the resin varnish to the support is not particularly limited, and coating devices known to those skilled in the art, such as a comma coater, bar coater, kiss coater, roll coater, gravure coater, or die coater, can be used. These coating devices can be appropriately selected depending on the film thickness. The drying temperature and drying time can be appropriately determined depending on the amount of organic solvent used, the boiling point of the organic solvent used, and other factors. For example, in the case of a resin varnish containing approximately 40 to 60% by mass of organic solvent, a resin film can be suitably formed by drying at 50 to 150°C for approximately 3 to 10 minutes.

[0101] [Laminate] The laminate of this embodiment is a laminate having one or more selected from the group consisting of a cured product of the resin composition of this embodiment, a cured product of a prepreg, and a cured product of a resin film, and a metal foil. The laminate of this embodiment can be produced, for example, by placing metal foil on one or both sides of a single prepreg of this embodiment, or by placing metal foil on one or both sides of a prepreg obtained by stacking two or more prepregs of this embodiment (preferably 2 to 30 sheets, more preferably 3 to 15 sheets), and then hot-pressing and molding. In the laminate obtained by this production method, the prepreg of this embodiment is C-staged. In this disclosure, C-staging refers to bringing the prepreg to the C-stage state defined in JIS K6900 (1994). Note that a laminate having metal foil is sometimes referred to as a metal-clad laminate.

[0102] The metal of the metal foil is not particularly limited, but from the viewpoint of electrical conductivity, it may be copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing one or more of these metal elements, with copper and aluminum being preferred, and copper being more preferred. The conditions for hot-press molding are not particularly limited, but can be, for example, a temperature of 100 to 300°C, a pressure of 0.2 to 10 MPa, and a time of 0.1 to 5 hours. Furthermore, hot-press molding can be performed using a vacuum press or the like to maintain a vacuum state for 0.5 to 5 hours.

[0103] [Printed Wiring Board] The printed wiring board of this embodiment has one or more selected from the group consisting of a cured product of the resin composition of this embodiment, a cured product of the prepreg, and a laminate of this embodiment. The printed wiring board of this embodiment can be manufactured by performing circuit formation processing such as drilling, metal plating, and etching of metal foil using one or more selected from the group consisting of the prepreg of this embodiment, the resin film of this embodiment, and the laminate of this embodiment by a known method, and further performing multilayer adhesive processing as needed to manufacture a multilayer printed wiring board. In the printed wiring board of this embodiment, the prepreg of this embodiment or the resin film of this embodiment is C-staged.

[0104] [Semiconductor Package] The semiconductor package of this embodiment is a semiconductor package having a printed wiring board and a semiconductor element. The semiconductor package of this embodiment can be manufactured by mounting a semiconductor element such as a semiconductor chip or memory at a predetermined position on the printed wiring board of this embodiment and sealing the semiconductor element with a sealing resin or the like.

[0105] The resin composition, prepreg, resin film, laminate, printed wiring board, and semiconductor package of this embodiment can be suitably used in electronic devices that handle high-frequency signals of 10 GHz or more. In particular, the printed wiring board is useful as a printed wiring board for millimeter-wave radar.

[0106] The present embodiment will be specifically described below with reference to examples, but the present embodiment is not limited to the following examples.

[0107] In each example, the number average molecular weight and weight average molecular weight (Mw) were measured by the following procedure. (I. Method for measuring number average molecular weight (Mn) and weight average molecular weight (Mw)) The number average molecular weight and weight average molecular weight were calculated by gel permeation chromatography (GPC) from a calibration curve using standard polystyrene. The calibration curve was approximated by a cubic equation using standard polystyrene: TSKstandard POLYSTYRENE (Types: A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) [manufactured by Tosoh Corporation, trade name]. The GPC measurement conditions are shown below. Apparatus: High-speed GPC apparatus HLC-8320GPC Detector: Ultraviolet absorption detector UV-8320 [manufactured by Tosoh Corporation] Column: Guard column; TSK Guard column SuperHZ-L + column; TSKgel SuperHZM-N + TSKgel SuperHZM-M + TSKgel SuperH-RC (all manufactured by Tosoh Corporation, trade names) Column size: 4.6 x 20 mm (guard column), 4.6 x 150 mm (column), 6.0 x 150 mm (reference column) Eluent: Tetrahydrofuran Sample concentration: 10 mg / 5 mL Injection volume: 25 μL Flow rate: 1.00 mL / min Measurement temperature: 40°C

[0108] (II. Measurement of Vinyl Group Modification Rate) The value obtained by the following method was taken as the vinyl group modification rate of the modified conjugated diene polymer B1-1 prepared in Production Example 1. A liquid containing the components (b1) and (b2) before the start of the reaction and a liquid containing the modified conjugated diene polymer obtained after the reaction were subjected to GPC measurement by the same method as above. The rate of decrease in the peak area derived from the component (b2) before and after the reaction, i.e., (peak area derived from the component (b2) before the reaction - peak area derived from the component (b2) after the reaction) × 100 / (peak area derived from the component (b2) before the reaction), was determined, and the obtained value was taken as the vinyl group modification rate.

[0109] Production Example 1 (Production of Modified Conjugated Diene Polymer B1-1) Components (b1) and (b2), an organic peroxide, and toluene as an organic solvent in the amounts shown in Table 1 were placed in a 2 L glass flask equipped with a thermometer, a reflux condenser, and a stirrer, and the mixture was allowed to react with stirring at 90 to 100°C for 5 hours in a nitrogen atmosphere to obtain a liquid containing modified conjugated diene polymer B1-1 (toluene diluted solution, solids concentration: 35% by mass). The vinyl group modification rate and number average molecular weight of the obtained modified conjugated diene polymer B1-1 are shown in Table 1.

[0110] The details of each component listed in Table 1 are as follows: [Component (b1)] Polybutadiene 1: 1,2-polybutadiene homopolymer, number average molecular weight = 1,200, vinyl group content = 85% or more [Component (b2)] Bismaleimide compound 1: 4,4'-diphenylmethane bismaleimide [Reaction catalyst] Organic peroxide: α,α'-bis(t-butylperoxy)diisopropylbenzene

[0111] Examples 1 to 6 and Comparative Examples 1 to 3 (Preparation of Resin Compositions and Resin Varnishes) The components shown in Table 2 were blended in the amounts shown in Table 2 (the amounts listed in Table 2 are parts by mass of solids) and mixed in toluene to obtain resin compositions (resin varnishes) with a non-volatile content (solids concentration) of 50% by mass. In Table 2, the blending amounts of each component are in parts by mass. In the case of solutions or dispersions, the blending amounts refer to parts by mass of solids. (Preparation of Prepregs) The resin varnishes prepared in each example were impregnated into glass cloth (Nitto Boseki Co., Ltd., #1078 type or #2116 type), which was then heated and dried at 120°C for 5 minutes to obtain prepregs. The resin composition content in the prepregs using #1078 type glass cloth (for evaluation of transmission loss and appearance) was 66% by mass, and the resin composition content in the prepregs using #2116 type glass cloth (for evaluation of flame retardancy) was 57% by mass. Flame retardancy was evaluated using a prepreg made with #2116 type glass cloth according to the measurement method described below. (Preparation of Double-Sided Copper-Clad Laminate) Six layers of prepreg (prepreg made with #1078 type glass cloth) were stacked on both sides of which 12 μm-thick electrolytic copper foil "3EC-M3-VLP-18" (trade name, manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed with the adhesive surface facing the prepreg, and heated and pressed at 180°C for 60 minutes under vacuum pressing conditions of 3 MPa, to prepare a double-sided copper-clad laminate. The resulting double-sided copper-clad laminate was evaluated for transmission loss and appearance according to the measurement methods described below. The results are shown in Table 2.

[0112] [Measurement Method] (1) Measurement Method of Dielectric Loss Tangent (Df) - Transmission Loss The double-sided copper-clad laminate obtained in each example was immersed in a 10% by mass solution of ammonium persulfate, a copper etching solution, to remove the copper foil, and a 2 mm x 50 mm evaluation board was prepared from the evaluation board. The dielectric loss tangent (Df) of the evaluation board was measured in the 10 GHz band at an ambient temperature of 25°C using the cavity resonator perturbation method. The dielectric loss tangent (Df) is preferably 0.0020 or less, more preferably 0.0018 or less, and even more preferably 0.0017 or less.

[0113] (2) Burn Time - Flame Retardancy The prepregs obtained in each example (prepregs using #2116 type glass cloth) were stacked to a thickness of 1.6 mm, and electrolytic copper foil "3EC-M3-VLP-18" (trade name, manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on top and bottom with the adhesive surface facing the prepreg. A double-sided copper-clad laminate was produced by heating and pressing at 180 °C for 60 minutes under vacuum pressing conditions of 3 MPa. The obtained double-sided copper-clad laminate was immersed in a 10% by mass solution of ammonium persulfate, a copper etching solution, to remove the copper foil, and then cut into five evaluation boards measuring 1.3 cm x 12.5 cm each. A vertical combustion test (UL94 flammability test) was performed on five obtained evaluation boards, and each was exposed to flame twice, measuring the combustion time after the first exposure and the combustion time after the second exposure, and the average combustion time for the five evaluation boards was calculated. In both the first and second flame contacts, the average combustion time is preferably 10 seconds or less, more preferably 7 seconds or less, and even more preferably 5 seconds or less.

[0114] (3) Appearance The double-sided copper-clad laminate obtained in each example was immersed in a 10% by mass solution of ammonium persulfate, which is a copper etching solution, to remove the copper foil, and the evaluation board was visually observed and evaluated according to the following evaluation criteria: A: No smears were found anywhere on the surface. B: Smears were observed only on the edges. C: Smears were observed at least in the center.

[0115]

[0116] The details of the components in Table 2 are as follows: [Component (A)] Maleimide compound A-1: ​​indane ring-containing aromatic bismaleimide (number average molecular weight: 1,200) Maleimide compound having a biphenylaralkyl skeleton "MIR-3000" (trade name, manufactured by Nippon Kayaku Co., Ltd.)

[0117] [Component (B)] Modified conjugated diene polymer B1-1: Modified conjugated diene polymer B1-1 obtained in Production Example 1 Styrene-based elastomer B2-1: Hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene content: 30% by mass, weight average molecular weight: 115,200

[0118] [Component (X)] Component (X1): Filled flame retardant X1-1: aluminum tris(diethylphosphinate) (see the following structural formula);

[0119] Component (X2): Compatible flame retardant X2-1: a phosphorus compound-based flame retardant having the following structure:

[0120] [Component (Y)] Component (Y1): Filled flame retardant Y1-1: decabromodiphenylethane (see structural formula below);

[0121] Component (Y2): Compatible flame retardant Y2-1: a halogen-based flame retardant having the following structure

[0122] [Component (C)] Inorganic filler C-1: silane coupling-treated fused spherical silica, average particle size 0.5 μm [Component (D)] Curing accelerator D-1: α,α'-bis(t-butylperoxy)diisopropylbenzene

[0123] As is clear from Table 2, the double-sided copper-clad laminates obtained in each Example have a small dielectric dissipation factor (Df), resulting in low transmission loss, excellent flame retardancy, and good appearance. On the other hand, the double-sided copper-clad laminate of Comparative Example 1 has a high dielectric dissipation factor (Df), poor flame retardancy compared to the Examples, and poor appearance. In Comparative Example 2, the dielectric dissipation factor (Df) was improved and the flame retardancy was good, but the appearance was poor. In Comparative Example 3, the dielectric dissipation factor (Df) was relatively good and the flame retardancy was excellent, but the appearance was poor. As such, it can be seen that it is not easy to achieve low transmission loss and excellent flame retardancy while also improving the appearance of a laminate.

Claims

1. A resin composition containing (A) a thermosetting resin, (B) a polymer having a hydrocarbon chain or a polyether chain, (X) a phosphorus compound-based flame retardant, and (Y) a flame retardant other than the phosphorus compound-based flame retardant, wherein the (X) component does not contain the (X1) filler flame retardant and the (Y) component does not contain the (Y1) filler flame retardant, or, when the (X) component contains the (X1) filler flame retardant or the (Y) component contains the (Y1) filler flame retardant, the content of the (X1) filler flame retardant and the content of the (Y1) filler flame retardant in total is 25 parts by mass or less per 100 parts by mass of solids in the resin composition.

2. The resin composition according to claim 1, wherein the component (X) contains a compatible flame retardant (X2).

3. The resin composition according to claim 1, wherein the component (Y) contains a compatible flame retardant (Y2).

4. The resin composition according to claim 1, wherein the component (A) comprises at least one selected from the group consisting of epoxy resins, maleimide compounds, phenolic resins, polyimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins and melamine resins.

5. The resin composition according to claim 1, wherein the component (B) is at least one selected from the group consisting of conjugated diene polymers, styrene-based elastomers, and modified products thereof.

6. The resin composition according to claim 1, wherein the component (X) comprises at least one member selected from the group consisting of (X-i) a phosphate compound, (X-ii) a phosphine oxide compound, (X-iii) a phosphaphenanthrene compound, (X-iv) a metal salt of phosphinic acid, and (X-v) an organic nitrogen-containing phosphorus compound.

7. The resin composition according to claim 1, wherein the component (X) has two or more phosphorus atoms in one molecule.

8. The resin composition according to claim 1, wherein the component (Y) is a halogen-based flame retardant.

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

10. The resin composition according to claim 1, further comprising (D) a curing accelerator.

11. A prepreg containing the resin composition according to claim 1 or a semi-cured product of said resin composition.

12. A resin film containing the resin composition according to claim 1 or a semi-cured product of said resin composition.

13. A laminate comprising a cured product of the resin composition according to claim 1 or a cured product of the prepreg according to claim 11, and a metal foil.

14. A printed wiring board having a cured product of the resin composition according to claim 1.

15. A semiconductor package comprising the printed wiring board according to claim 14 and a semiconductor element.

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