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

Abstract

Provided is a resin composition that exhibits excellent flame retardancy and that reduces the minimum melt viscosity of a prepreg. Also provided are a prepreg, a resin film, a laminate, a printed wiring board, and a semiconductor package, which are produced using the resin composition. Specifically, the resin composition contains (A) a thermosetting resin, (X) a metal phosphate, and (Y) a phosphazene compound.

Description

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

[0001] This disclosure relates to resin compositions, prepregs, resin films, laminates, printed circuit boards, and semiconductor packages.

[0002] In mobile communication devices such as mobile phones, their base station equipment, network infrastructure equipment such as servers and routers, and electronic devices such as large computers, the speed and capacity of the signals used are increasing year by year. Accordingly, the substrate materials of printed circuit boards mounted on these electronic devices are required to reduce the transmission loss of high-frequency signals. Furthermore, from a safety standpoint, high flame retardancy is required for printed circuit boards. Conventionally, flame retardants such as metal phosphate salts have been used in substrate materials (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2021-176926

[0004] However, the inventors' investigations revealed that prepregs containing flame retardants such as metal phosphate salts have a high minimum melt viscosity. A high minimum melt viscosity tends to reduce the embedding ability of the resin component into the circuit pattern (circuit embedding ability) in the prepreg.

[0005] In view of the above circumstances, this disclosure aims to provide a resin composition that exhibits excellent flame retardancy and has a low minimum melt viscosity for the prepreg. Furthermore, it also aims to provide prepregs, resin films, laminates, printed circuit boards, and semiconductor packages manufactured using the resin composition.

[0006] The present inventors have conducted studies to achieve the above objective and have found that the present disclosure can achieve the above objective. The present disclosure includes the following embodiments [1] to

[16] . [1] A resin composition comprising (A) a thermosetting resin, (X) a metal phosphate salt, and (Y) a phosphazene compound. [2] The resin composition according to [1], wherein component (A) comprises at least one selected from the group consisting of epoxy resin, maleimide compound, phenol resin, polyimide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene resin, silicone resin, triazine resin, and melamine resin. [3] The resin composition according to [1] or [2], wherein component (X) is a metal salt of dialkylphosphinic acid. [4] The resin composition according to any one of [1] to [3], wherein the metal salt in component (X) is a lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, titanium salt, or zinc salt. [5] The resin composition according to any one of [1] to [4], wherein the content of component (X) is 0.5 to 10 parts by mass per 100 parts by mass of solids in the resin composition. [6] The resin composition according to any one of [1] to [5], wherein the content of component (Y) is 0.5 to 10 parts by mass per 100 parts by mass of solids in the resin composition. [7] The resin composition according to any one of [1] to [6], wherein the ratio of the content of component (X) to the content of component (Y) [(X) / (Y)] is 30 / 70 to 70 / 30 by mass. [8] The resin composition according to any one of [1] to [7], further containing an elastomer (B). [9] The resin composition according to any one of [1] to [8], further comprising (C) a crosslinking agent.

[10] The resin composition according to any one of [1] to [9], further comprising (D) an inorganic filler.

[11] The resin composition according to any one of [1] to

[10] , further comprising (E) a curing accelerator.

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

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

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

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

[14] A laminate having a cured resin composition according to any of [1] to

[11] above or a cured prepreg according to

[12] above, and a metal foil.

[15] A printed circuit board having a cured resin composition according to any of [1] to

[11] above.

[16] A semiconductor package having the printed circuit board according to

[15] above and a semiconductor element.

[0007] According to this disclosure, it is possible to provide a resin composition that exhibits excellent flame retardancy and has a low minimum melt viscosity for the prepreg. Furthermore, it is possible to provide prepregs, resin films, laminates, printed circuit boards, and semiconductor packages using the resin composition.

[0008] In the numerical ranges described in this disclosure, the upper or lower limits of the numerical range may be replaced with the values ​​shown in the examples. Furthermore, the lower and upper limits of a numerical range may be arbitrarily combined with the lower or upper limits of other numerical ranges. In the notation "AA to BB" for a numerical range, the numbers AA and BB at both ends are included in the range as the lower and upper limits, respectively. In this disclosure, for example, "10 or more" means 10 and numbers greater than 10, and this applies even if the numbers are different. Similarly, for example, "10 or less" means 10 and numbers less than 10, and this applies even if the numbers are different. Furthermore, unless otherwise specified, each component and material exemplified in this disclosure may be used alone or in combination of two or more. In this disclosure, if there are multiple substances corresponding to each component in the resin composition, unless otherwise specified, the content of each component in the resin composition means the total amount of such multiple substances present in the resin composition.

[0009] In this disclosure, "resin components" refers to all components of the resin composition that constitute the solid content, excluding inorganic compounds such as inorganic fillers described later. In this disclosure, "solid content" refers to components other than organic solvents described later, and components that are liquid at 25°C are also considered to be solid content. The expression "contains XX" as described in this disclosure means that XX may be contained in a reacted state if XX is reactable, or it may simply mean that XX is contained. Any combination of the information described in this disclosure is also included in this disclosure and these embodiments.

[0010] [Resin Composition] This embodiment is a resin composition containing (A) a thermosetting resin, (X) a metal phosphate salt, and (Y) a phosphazene compound. This resin composition is a thermosetting resin composition. By using a resin composition containing the above components (A), (X), and (Y), a resin composition is obtained that exhibits excellent flame retardancy and has a low minimum melt viscosity of the prepreg. The mechanism by which such results are obtained is considered to be as follows. (X) The metal phosphate salt is a flame retardant that tends not to dissolve in the resin composition (sometimes called a dispersed flame retardant). It is presumed that this is the reason why the minimum melt viscosity of the prepreg increases. However, it is presumed that (Y) the phosphazene compound is not the dispersed flame retardant, but a flame retardant that melts or dissolves in the resin composition, and this leads to a reduction in the minimum melt viscosity of the prepreg. The components contained in the resin composition of this embodiment will be described in detail below.

[0011] ((A) Thermosetting resin) Examples of component (A) include epoxy resins, maleimide compounds, phenolic resins, polyimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins (e.g., melamine resins), unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins (e.g., bismaleimidotriazine resins). Among these, 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 maleimide compounds from the viewpoint of low thermal expansion. Component (A) may be used alone or two or more may be used in combination.

[0012] 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. Epoxy resins are classified into various types based on differences in their main skeleton. Within each of the above types of epoxy resins, they are further classified into bisphenol-type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; alicyclic epoxy resins such as dicyclopentadiene type epoxy resin; aliphatic chain epoxy resins; novolac-type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, phenol aralkyl novolac type epoxy resin, and biphenyl aralkyl novolac type epoxy resin; stilbene type epoxy resin; naphthalene skeleton-containing epoxy resins such as naphthol novolac type epoxy resin and naphthol aralkyl type epoxy resin; biphenyl type epoxy resin; xylylene type epoxy resin; and dihydroanthracene type epoxy resin.

[0013] 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 their derivatives. 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 the nitrogen atoms of the maleimide groups are bonded to each other via organic groups.

[0014] The maleimide compounds having one or more N-substituted maleimide groups are not particularly limited, but preferably aromatic maleimide compounds 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, N-benzylmaleimide; 4,4'-diphenylmethanebismaleimide, bis(4-maleimidophenyl) ether, bis(4-maleimidophenyl) sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1, Examples include aromatic bismaleimide compounds having two N-substituted maleimide groups preferably bonded to an aromatic ring, such as 3-phenylenebismaleimide, m-phenylenebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, and indan ring-containing aromatic bismaleimide; aromatic polymaleimide compounds having three or more N-substituted maleimide groups preferably bonded to an aromatic ring, such as polyphenylmethanemaleimide and biphenylaralkyl-type maleimide; and aliphatic maleimide compounds such as N-dodecylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, and pyrophosphate binder-type long-chain alkylbismaleimide. Among these, from the viewpoint 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 the aromatic ring are preferred, aromatic polymaleimide compounds having three or more N-substituted maleimide groups bonded to the aromatic ring are more preferred, biphenyl aralkyl type maleimide and indane ring-containing aromatic bismaleimide are even more preferred, and the combined use of biphenyl aralkyl type maleimide and indane ring-containing aromatic bismaleimide is particularly preferred.When biphenylaralkyl maleimide and indane ring-containing aromatic bismaleimide are used in combination, their content ratio (biphenylaralkyl maleimide / indane ring-containing aromatic bismaleimide) is preferably 5 / 95 to 45 / 55 by mass ratio, more preferably 10 / 90 to 40 / 60, and even more preferably 15 / 85 to 35 / 65.

[0015] Herein, in this disclosure, the indan ring refers to a fused bicyclic structure of an aromatic six-membered ring and a saturated aliphatic five-membered ring. The indan ring-containing aromatic bismaleimide is preferably having a divalent group represented by the following general formula (a1-1).

[0016] (In the formula, R ａ１ The C1-C10 alkyl group, C1-C10 alkyloxy group, C1-C10 alkylthio group, C6-C10 aryl group, C6-C10 aryloxy group, C6-C10 arylthio group, C3-C10 cycloalkyl group, halogen atom, hydroxyl group, or mercapto group, where n1 is an integer from 0 to 3. ａ２ ~R ａ４ Each of these is an alkyl group having 1 to 10 carbon atoms. (* indicates a bonding site.)

[0017] As an indane ring-containing aromatic bismaleimide containing a divalent group represented by the general formula (a1-1), the one represented by the following general formula (a1-2) is preferred from the viewpoint of reducing transmission loss, adhesion to conductors, heat resistance, and ease of manufacture.

[0018] (In the formula, R ａ１ ~R ａ４ And n1 is the same as in the general formula (a1-1) above. R ａ５ Each of these is 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 of these is independently an integer from 0 to 4; and each of these is independently an integer from 0.95 to 10.0.

[0019] The indane ring-containing aromatic bismaleimide represented by the 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) from the viewpoints of reducing transmission loss, adhesion to a conductor, solvent solubility, and ease of production.

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

[0021] (In the formula, R ａ１ to R ａ４ and 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 indane ring-containing aromatic bismaleimide, and it may be produced by a known method.

[0023] Examples of the "derivatives" of the maleimide compounds mentioned above include addition reaction products of a maleimide compound having one or more (preferably two or more) N-substituted maleimide groups with an amine compound such as a monoamine compound or a diamine compound. Examples of the monoamine compounds include monoamine compounds having acidic substituents 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. The diamine compounds 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, and 4,4'-diaminodiphenyl Examples include diamine compounds having aromatic hydrocarbon groups, such as phenylthioether, 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 siloxanediamines.

[0024] (Content of component (A)) The content of thermosetting resin (A) in the resin composition of this embodiment is not particularly limited, but from the viewpoint of heat resistance and moldability, it is preferably 3 to 95% by mass, more preferably 5 to 80% by mass, even more preferably 10 to 60% by mass, particularly preferably 15 to 45% by mass, most preferably 15 to 35% by mass, and may also be 20 to 35% by mass, based on the total amount of solids in the resin composition.

[0025] ((X) Metal Phosphate) The resin composition of this embodiment contains (X) metal phosphate. (X) Metal phosphate functions as a flame retardant. The (X) component has a flame retardant mechanism in which the film of phosphoric acid generated by decomposition blocks oxygen, and further, by carbonizing organic substances through dehydration, a film called char is formed on the surface of the combustible material to block oxygen. The (X) component may be used alone or in combination of two or more. As the (X) component, a metal salt of dialkylphosphinic acid is preferable. Here, examples of the "metal salt" include lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, titanium salt, zinc salt, etc. Among these, aluminum salt is preferable as the metal salt. Further, examples of the alkyl group of 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 preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and an ethyl group is even more preferable. That is, the (X) component is preferably a metal salt of diethylphosphinic acid, and more preferably an aluminum salt of diethylphosphinic acid.

[0026] ((Content of (X) Component)) The content of the (X) metal phosphate in the resin composition of this embodiment is not particularly limited, but is preferably 0.5 to 10% by mass, more preferably 1 to 10% by mass, further preferably 1 to 5% by mass, particularly preferably 1.5 to 4% by mass, and most preferably 1.5 to 3.5% by mass with respect to the total solid content in the resin composition. When the content of the (X) metal phosphate in the resin composition of this embodiment is at least the above lower limit value, the flame retardancy tends to be high, and when it is at most the above upper limit value, the minimum melt viscosity of the prepreg can be suppressed from increasing too much.

[0027] ((Y) Phosphazene Compound) The resin composition of this embodiment contains a (Y) phosphazene compound. The (Y) phosphazene compound functions as a flame retardant. The (Y) component may be used alone or two or more may be used in combination. The (Y) component is preferably one having a structural unit represented by the following general formula (Y-1) or general formula (Y-2), and more preferably one having a structural unit represented by the following general formula (Y-1).

[0028] (In the formula, R Ｙ１ and R Ｙ２ Each of these independently represents an organic group having 1 to 20 carbon atoms.

[0029] (In the formula, Z Ｙ１ (This indicates an aromatic hydrocarbon group with 6 to 20 carbon atoms.)

[0030] In the above general formula (Y-1), R Ｙ１ and R Ｙ２ Examples of organic groups having 1 to 20 carbon atoms include aliphatic hydrocarbon groups having 1 to 20 carbon atoms and aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0031] R Ｙ１ and R Ｙ２Examples of C1-C20 organic groups represented by include C1-C20 aliphatic hydrocarbon groups, C1-C20 alkyl groups, C2-C20 alkenyl groups, and C2-C20 alkynyl groups. The above aliphatic hydrocarbon groups may be linear, branched, or cyclic. Examples of C1-C20 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, 2-ethylhexyl, and cyclohexyl groups. Examples of C2-C20 alkenyl groups include vinyl, propenyl, and butenyl groups. Examples of C2-C20 alkynyl groups include 2-propynyl and 3-butynyl groups. The C1-C20 aliphatic hydrocarbon groups may or may not have substituents. Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, aromatic hydrocarbon groups, acyl groups, alkoxy groups, and groups formed by linking these substituents. When an aliphatic hydrocarbon group has substituents, the carbon number mentioned above also includes the carbon number of the substituents.

[0032] R Ｙ１ and R Ｙ２ The number of carbon atoms in the aromatic hydrocarbon group having 6 to 20 carbon atoms, which is listed as an organic group having 1 to 20 carbon atoms as indicated by , is preferably 6 to 15, and more preferably 6 to 10. Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include phenyl groups, naphthyl groups, biphenyl groups, anthranyl groups, etc. The aromatic hydrocarbon group having 6 to 20 carbon atoms may or may not have substituents. Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, aliphatic hydrocarbon groups, acyl groups, alkoxy groups, cyano groups, and groups formed by linking these substituents. A cyano group is preferred as the substituent. Note that if the aromatic hydrocarbon group has substituents, the above number of carbon atoms also includes the number of carbon atoms of the substituents. Among these, R Ｙ１ and R Ｙ２ Of the organic groups having 1 to 20 carbon atoms, from the viewpoint of flame retardancy, aromatic hydrocarbon groups having 6 to 20 carbon atoms are preferred, unsubstituted phenyl groups and substituted phenyl groups are more preferred, and unsubstituted phenyl groups and cyanophenyl groups are even more preferred.

[0033] In the above general formula (Y-2), Z Ｙ１ Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include divalent aromatic hydrocarbon groups such as phenylene groups, biphenylylene groups, and naphthalenediyl groups. Among these, biphenylylene groups are preferred. The aromatic hydrocarbon group may or may not have substituents. Examples of substituents include hydroxyl groups, carboxyl groups, halogen atoms, aliphatic hydrocarbon groups, acyl groups, alkoxy groups, cyano groups, and groups formed by linking these substituents.

[0034] The phosphazene compound may be a linear phosphazene compound or a cyclic phosphazene compound, but a cyclic phosphazene compound is preferred. As the cyclic phosphazene compound, a phosphazene compound represented by the following general formula (Y-3) is preferred, and a phosphazene compound represented by the following general formula (Y-4) is more preferred.

[0035] (In the formula, Ar Ｙ１ and Ar Ｙ２ Each of these independently represents an aromatic hydrocarbon group having 6 to 20 carbon atoms. Ｙ１ (This represents an integer between 3 and 20.) (In the formula, Ar Ｙ３ ~Ar Ｙ８ Each of these independently represents an aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0036] Ar in the above general formula (Y-3) Ｙ１ and Ar Ｙ２ The aromatic hydrocarbon group having 6 to 20 carbon atoms, and Ar in the above general formula (Y-4) Ｙ３ ~Ar Ｙ８ The explanation for the aromatic hydrocarbon group having 6 to 20 carbon atoms shown is as follows: R in the general formula (Y-1) above. Ｙ１ and R Ｙ２ This is the same as the explanation for aromatic hydrocarbon groups with 6 to 20 carbon atoms shown. n in the above general formula (Y-3) Ｙ１ represents an integer between 3 and 20, preferably an integer between 3 and 10, more preferably an integer between 3 and 5, and even more preferably 3.

[0037] More specifically, as cyclic phosphazene compounds, from the viewpoint of flame retardancy, low transmission loss, and minimum melt viscosity, phosphazene compounds represented by the following general formula (Y-5) and phosphazene compounds represented by the following general formula (Y-6) are preferred, and in particular from the viewpoint of minimum melt viscosity, phosphazene compounds represented by the following general formula (Y-5) are more preferred. On the other hand, in the case of phosphazene compounds represented by the following general formula (Y-6), there is a tendency for low transmission loss to be easily achieved.

[0038] (In the formula, n Ｙ２ (This represents an integer between 3 and 20.)

[0039] (In the formula, n Ｙ３ (This indicates 3 or 4.)

[0040] The melting point of component (Y) is preferably 60 to 140°C, more preferably 65 to 125°C, and may also be 60 to 90°C, 65 to 85°C, 90 to 140°C, or 100 to 125°C. When the melting point of component (Y) is above the lower limit, it becomes solid at room temperature, making it less likely to bleed out in the prepreg, and as a result, the tackiness of the prepreg tends to be suppressed. When it is below the upper limit, the minimum melt viscosity of the prepreg tends to be lower.

[0041] (Content of component (Y)) The content of the (Y) phosphazene compound in the resin composition of this embodiment is not particularly limited, but is preferably 0.5 to 10% by mass, more preferably 1 to 10% by mass, even more preferably 1 to 5% by mass, particularly preferably 1.5 to 4% by mass, and most preferably 1.5 to 3.5% by mass, relative to the total amount of solids in the resin composition. When the content of the (Y) phosphazene compound in the resin composition of this embodiment is above the lower limit, the flame retardancy tends to be increased and the minimum melt viscosity of the prepreg tends to be lower, and when it is below the upper limit, it tends to suppress an increase in the dielectric constant (Dk).

[0042] (Content ratio of component (X) and component (Y)) The content ratio of component (X) and component (Y) [(X) / (Y)] (mass ratio) in the resin composition of this embodiment is not particularly limited, but from the viewpoint of the minimum melt viscosity of the prepreg, it is preferably 30 / 70 to 70 / 30, more preferably 40 / 60 to 60 / 40, and even more preferably 45 / 55 to 55 / 45.

[0043] ((B) Elastomer) The resin composition of this embodiment is not particularly limited, but from the viewpoint of low transmission loss, it is preferable to contain (B) elastomer. In this disclosure, elastomer is defined as a polymer compound that exhibits rubber elasticity at 25°C. The rubber elasticity is preferably such that the modulus of elasticity (Young's modulus) is 1 to 10 MPa. Examples of the (B) component include styrene elastomers, olefin elastomers, urethane elastomers, polyester elastomers, polyamide elastomers, acrylic elastomers, silicone elastomers, etc. The (B) component may be used alone or two or more may be used in combination.

[0044] As for component (B), a styrene-based elastomer is preferred from the viewpoint of low transmission loss, and a styrene-based thermoplastic elastomer is more preferred. As for the styrene-based elastomer, it is sufficient to have structural units derived from a styrene-based compound, and from the viewpoint of low transmission loss, adhesion to conductors, heat resistance and low thermal expansion, one or more selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS or SBBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and styrene-maleic anhydride copolymer (SMA) is preferred, one or more selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) and hydrogenated styrene-isoprene-styrene block copolymer (SEPS) is more preferred, and hydrogenated styrene-butadiene-styrene block copolymer (SEBS) is even more preferred. Furthermore, the styrene elastomer (excluding SMA as described above) may be modified with an acid anhydride such as maleic anhydride. Examples include SEBS modified with an acid anhydride such as maleic anhydride, and SEPS modified with an acid anhydride such as maleic anhydride. The acid value of the acid-modified styrene elastomer (excluding SMA as described above) is not particularly limited, but is between 2 and 20 mgCH. ３ ONa / g is preferred, and 5 to 15 mg CH ３ ONa / g is more preferably 7-13 mgCH ３ ONa / g is even more preferred. Here, the acid value is sodium methoxide (CH ３ It can be measured by titration using ONa.

[0045] In component (B), the content of styrene-derived structural units [hereinafter sometimes referred to as "styrene content"] is not particularly limited, but from the viewpoint of low transmission loss, adhesion to conductors, heat resistance and low thermal expansion, it is preferably 5 to 80% by mass, more preferably 10 to 75% by mass, even more preferably 15 to 60% by mass, particularly preferably 18 to 45% by mass, and most preferably 20 to 40% by mass.

[0046] The number-average molecular weight (Mn) of component (B) is not particularly limited, but is preferably 12,000 to 1,000,000, more preferably 30,000 to 500,000, may be 50,000 to 200,000, may be 50,000 to 150,000, may be 50,000 to 100,000, and may be 60,000 to 90,000. In this disclosure, the number-average molecular weight (Mn) is a value measured in polystyrene terms by gel permeation chromatography (GPC), and more specifically, is a value measured by the method described in the examples.

[0047] (Content of component (B)) When the resin composition of this embodiment contains component (B), the content of component (B) is not particularly limited, but is preferably 1 to 35% by mass, more preferably 3 to 30% by mass, even more preferably 5 to 25% by mass, and particularly preferably 10 to 25% by mass, relative to the total amount of solids in the resin composition. When the content of component (B) is above the lower limit, the low transmission loss tends to improve, and when it is below the upper limit, good heat resistance, moldability, processability, and flame retardancy tend to be obtained.

[0048] (C) Crosslinking Agent The resin composition of this embodiment may further contain (C) a crosslinking agent. The inclusion of (C) a crosslinking agent tends to improve the compatibility between component (A) and component (B). Component (C) is preferably a compound having a structure derived from a maleimide compound and a structure derived from butadiene, and more preferably a compound having a structure derived from a maleimide compound containing an indane skeleton and a structure derived from butadiene. Furthermore, the structure derived from the maleimide compound is preferably a structure derived from a bismaleimide compound containing an indane skeleton, and more preferably a structure derived from an indane ring-containing aromatic bismaleimide.

[0049] Compounds having a structure derived from a maleimide compound and a structure derived from butadiene can be produced by reacting a maleimide compound and butadiene in the presence of an organic peroxide. The organic peroxide is not particularly limited, but examples include benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, and t-butyl perbenzoate. The amount of organic peroxide used is preferably 0.1 to 10 parts by mass per 100 parts by mass of the total amount of the maleimide compound and butadiene. In compounds having a structure derived from a maleimide compound and a structure derived from butadiene, the extent to which the vinyl groups in the butadiene are modified by the maleimide compound (hereinafter sometimes referred to as the "vinyl group modification rate") is not particularly limited, but from the viewpoint of compatibility with other resins, dielectric properties, low thermal expansion, and heat resistance, it is preferably 20 to 70%, more preferably 30 to 60%, and even more preferably 35 to 50%. Here, the vinyl group modification rate is the value obtained by the method described in the examples.

[0050] The butadiene used in the production of a compound having a structure derived from a maleimide compound and a structure derived from butadiene preferably has a number average molecular weight of 200 to 10,000, more preferably 500 to 5,000, even more preferably 500 to 2,500, and particularly preferably 800 to 2,000. The butadiene preferably contains structural units having 1,2-vinyl groups, and the content of structural units having 1,2-vinyl groups (hereinafter sometimes referred to as "vinyl group content") is not particularly limited, but is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 85 mol% or more, relative to the total structural units of butadiene. Furthermore, the upper limit of the vinyl group content is not particularly limited and may be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0051] (Content of component (C)) When the resin composition of this embodiment contains component (C), the content of component (C) is not particularly limited, but is preferably 1 to 40% by mass, more preferably 1 to 30% by mass, even more preferably 3 to 20% by mass, and particularly preferably 5 to 15% by mass, relative to the total amount of solids in the resin composition. If the content of component (C) is above the lower limit, the compatibility between component (A) and component (B) tends to be good, and if it is below the upper limit, it tends to be easier to maintain good heat resistance and flame retardancy.

[0052] (D) Inorganic Filler The resin composition of this embodiment tends to have improved low thermal expansion, heat resistance and flame retardancy by further containing (D) an inorganic filler. The (D) component is not particularly limited, but examples include silica, alumina, titanium oxide, mica, beryllium, 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 (zinc molybdate, etc.), talc, aluminum borate, silicon carbide, etc. The (D) component may be used alone or two or more may be used in combination. Among these, silica, alumina, mica, and talc are preferred from the viewpoint of low thermal expansion, heat resistance and flame retardancy, silica and alumina are more preferred, and silica is even more preferred. Examples of silica include crushed silica, fumed silica, and fused silica (fused spherical silica).

[0053] The shape and particle size of component (D) are not particularly limited, but the particle size 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. Here, particle size refers to the average particle diameter, which is the particle diameter at the point corresponding to 50% of the volume when the cumulative frequency distribution curve by particle diameter is determined with the total volume of particles set to 100%. The particle size of component (D) can be measured using a particle size distribution analyzer that uses laser diffraction scattering or the like.

[0054] (Content of component (D)) When the resin composition of this embodiment contains component (D), the content of component (D) is not particularly limited, but from the viewpoint of low thermal expansion, heat resistance and flame retardancy, it is preferably 5 to 70% by mass, more preferably 15 to 60% by mass, even more preferably 20 to 55% by mass, and particularly preferably 25 to 50% by mass, based on the total amount of solids in the resin composition.

[0055] Furthermore, component (D) may be an inorganic filler that has been pre-treated with a coupling agent by a dry or wet method, from the viewpoint of improving the dispersibility of component (D) and the adhesion between component (D) and the organic components in the resin composition. The coupling agent is not particularly limited, and for example, a silane coupling agent or a titanate coupling agent can be appropriately selected and used. One type of coupling agent may be used alone, or two or more types may be used in combination. Also, the amount of coupling agent used is not particularly limited.

[0056] In this embodiment, when component (D) is used, in order to improve the dispersibility of component (D) in the resin composition, it may be used as a slurry in which component (D) is pre-dispersed in an organic solvent, if necessary. Examples of organic solvents include those described later.

[0057] (E) Curing accelerator The resin composition of this embodiment, by further containing a curing accelerator (E), tends to have improved curability, resulting in better low transmission loss, heat resistance, adhesion to conductors, elastic modulus, and glass transition temperature. When the resin composition of this embodiment contains a curing accelerator (E), a suitable curing accelerator (E) can be appropriately selected according to the type of thermosetting resin (B) component used. One type of curing accelerator (E) may be used alone, or two or more types may be used in combination.

[0058] (E) Component may include amine-based curing accelerators, imidazole-based curing accelerators, phosphorus-based curing accelerators, organometallic salts, acidic catalysts, organic peroxides, etc. In this embodiment, imidazole-based curing accelerators are not classified as amine-based curing accelerators. Examples of amine-based curing accelerators include amine compounds having primary to tertiary amines such as triethylamine, pyridine, tributylamine, dicyandiamide, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; and quaternary ammonium compounds. Examples of imidazole-based curing accelerators include imidazole compounds such as methylimidazole, phenylimidazole, 2-undecylimidazole, and isocyanate-masquimidazole (for example, an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole). Examples of phosphorus-based curing accelerators include tertiary phosphines such as triphenylphosphine, and quaternary phosphonium compounds such as the tri-n-butylphosphine addition reaction product of p-benzoquinone. Examples of organometallic salts include carboxylates of manganese, cobalt, zinc, etc. Examples of acidic catalysts include p-toluenesulfonic acid. Examples of organic peroxides include dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyn-3,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and α,α'-di(t-butylperoxy)diisopropylbenzene. Among these, imidazole-based curing accelerators are preferred from the viewpoint of obtaining better low transmission loss, heat resistance, adhesion to conductors, elastic modulus, and glass transition temperature. Furthermore, an embodiment using an imidazole-based curing accelerator in combination with an organic peroxide is also preferred.

[0059] (Content of component (E)) When the resin composition of this embodiment contains component (E), the content of component (E) is not particularly limited, but is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.05 to 3% by mass, relative to the total solid content of the resin composition. When the content of component (E) is within the above range, there is a tendency for low transmission loss, heat resistance, storage stability, and moldability to be good.

[0060] (Other Components) The resin composition of this embodiment may further contain, if necessary, one or more optional components such as flame retardants [excluding components (X) and (Y) above], flame retardant aids, coupling agents, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, and lubricants. Each of the above optional components may be used individually or in combination of two or more.

[0061] If the resin composition of this embodiment contains the above-mentioned optional components, the amount thereof is not particularly limited, but may be 0.01% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 30% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, based on the total amount of resin components. Furthermore, the resin composition of this embodiment may not contain the above-mentioned optional components depending on the desired performance. In the resin composition of this embodiment, the total amount of components (A) to (E) and components (X) and (Y) is preferably 70% by mass or more (including 100% by mass), more preferably 90% by mass or more (including 100% by mass), even more preferably 95% by mass or more (including 100% by mass), may be 99% by mass or more (including 100% by mass), or may be 100% by mass, based on the total amount of solids.

[0062] The resin composition of this embodiment can be produced by mixing component (A), component (X), and component (Y), and other components as needed, in a known manner. In this case, each component may be dissolved or dispersed in the organic solvent while stirring. The mixing order, temperature, time, and other conditions are not particularly limited and can be set arbitrarily. Hereinafter, the resin composition containing the organic solvent may be referred to as a resin varnish. Examples of the organic solvent include alcohol-based solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfur-containing solvents such as dimethyl sulfoxide; and ester-based solvents such as γ-butyrolactone. These organic solvents may be used individually or in combination of two or more. The solid content concentration in the resin varnish is preferably 10 to 70% by mass, more preferably 20 to 65% by mass, and may also be 20 to 60% by mass or 35 to 60% by mass.

[0063] [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 fibrous substrate. The prepreg is formed using the resin composition or resin film of this embodiment and a sheet-like fibrous substrate, and can be obtained, for example, by impregnating or coating the sheet-like fibrous substrate with the resin composition or resin film of this embodiment, drying it, and partially curing it (B-stage) as necessary. More specifically, for example, the prepreg of this embodiment can be manufactured by heating and drying it in a drying oven at a temperature of 80 to 200°C for 1 to 30 minutes to partially cure it (B-stage). Here, in this disclosure, B-stage means reaching the B-stage state as defined in JIS K6900 (1994). The amount of resin composition used can be appropriately determined for the purpose of making the solid content concentration derived from the resin composition in the prepreg after drying 30 to 90% by mass. By setting the solid content concentration within the above range, better moldability tends to be obtained when forming laminated boards.

[0064] As the sheet-like fiber base material for the prepreg, known materials used in laminates for various electrical insulating materials can be used. The sheet-like fiber base material is not particularly limited, but it is preferably a sheet-like fiber reinforcing base material used for the purpose of reinforcing the prepreg. Examples of materials for the sheet-like fiber base material 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 base materials preferably have a shape such as woven fabric, non-woven fabric, rawhide, chopped strand mat, or surfacing mat, and more preferably a woven fabric shape. The thickness of the sheet-like fiber base material is not particularly limited, but for example, a thickness of 0.02 to 0.5 mm can be used. Furthermore, the sheet-like fiber base material can be surface-treated with a coupling agent or the like, or mechanically opened, from the viewpoint of impregnation of the resin composition, heat resistance when used as a laminate, moisture resistance, and processability.

[0065] As a method for impregnating or coating a sheet-like fibrous substrate with a resin composition, the following hot-melt method or solvent method can be employed. The hot-melt method does not involve the resin composition containing an organic solvent, and involves (1) first coating a coated paper with good release properties from the resin composition and then laminating it onto the sheet-like fibrous substrate, or (2) coating the sheet-like fibrous substrate with the resin composition using a die coater. On the other hand, the solvent method involves including an organic solvent in the resin composition, impregnating the sheet-like fibrous substrate with the resin composition by immersing it in the resulting resin composition, and then drying it.

[0066] [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 manufactured, for example, by applying a resin composition containing an organic solvent, i.e., a resin varnish, to a support, heating and drying it, and semi-curing (B-stage) it as needed. Examples of support materials 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 films and polyimide films. Alternatively, metal foils such as copper foil and aluminum foil, or release paper may be used as support materials. The support material may be subjected to surface treatments such as mat treatment or corona treatment. The support material may also be subjected to release treatment with a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, etc. The thickness of the support material is not particularly limited, but is preferably 10 to 150 μm, more preferably 25 to 50 μm.

[0067] The method for applying the resin varnish to the support is not particularly limited, and coating apparatus known to those skilled in the art, such as comma coaters, bar coaters, kiss coaters, roll coaters, gravure coaters, and die coaters, can be used. These coating apparatuses can be appropriately selected depending on the film thickness. The drying temperature and drying time can be appropriately determined according to the amount of organic solvent used and the boiling point of the organic solvent used, but for example, in the case of a resin varnish containing about 40 to 60% by mass of organic solvent, a resin film can be suitably formed by drying at 50 to 150°C for about 3 to 10 minutes.

[0068] [Laminate] The laminate of this embodiment is a laminate having one or more selected from the group consisting of a cured resin composition of this embodiment, a cured prepreg, and a cured resin film, and a metal foil. The laminate of this embodiment can be manufactured, for example, by placing a metal foil on one or both sides of a single prepreg of this embodiment, or by placing a metal foil on one or both sides of a prepreg obtained by stacking two or more (preferably 2 to 30, more preferably 3 to 15) prepregs of this embodiment, and then by heating and pressing it. In the laminate obtained by this manufacturing method, the prepreg of this embodiment is C-staged. In this disclosure, C-staged means being in the state of C-stage as defined in JIS K6900 (1994). The laminate having a metal foil is sometimes called a metal-clad laminate.

[0069] The metal of the metal foil is not particularly limited, but from the viewpoint of 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 heat and pressure molding are not particularly limited, but for example, it can be carried out in the range of 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, the heat and pressure molding can be carried out by using a vacuum press or the like to maintain a vacuum state for 0.5 to 5 hours.

[0070] [Printed Wiring Board] The printed wiring board of this embodiment comprises one or more selected from the group consisting of a cured resin composition of this embodiment, a cured prepreg, and a laminate of this embodiment. The printed wiring board of this embodiment can be manufactured by 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, and performing circuit formation processing such as drilling, metal plating, and etching of metal foil by known methods, and further, if necessary, a multilayer printed wiring board can be manufactured by performing multilayer bonding processing. In the printed wiring board of this embodiment, the prepreg of this embodiment or the resin film of this embodiment is C-staged.

[0071] [Semiconductor Package] The semiconductor package of this embodiment is a semiconductor package having a printed circuit board and semiconductor elements. The semiconductor package of this embodiment can be manufactured by mounting semiconductor elements such as semiconductor chips and memory at predetermined positions on the printed circuit board of this embodiment and sealing the semiconductor elements with a sealing resin or the like.

[0072] The resin composition, prepreg, resin film, laminate, printed circuit board, and semiconductor package of this embodiment can be suitably used in electronic equipment that handles high-frequency signals of 10 GHz or higher. In particular, the printed circuit board is useful as a printed circuit board for millimeter-wave radar.

[0073] The embodiment will be described in detail below with reference to examples. However, this embodiment is not limited to the following examples.

[0074] In each example, the number-average molecular weight was measured using the following procedure. (I. Method for measuring number-average molecular weight (Mn)) The number-average molecular weight was calculated from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve was approximated by a cubic equation using standard polystyrene: TSK standard POLYSTYRENE (Type; 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. Instrument: High-speed GPC instrument HLC-8320GPC Detector: UV-8320 ultraviolet absorption detector [manufactured by Tosoh Corporation] Column: Guard column; TSK Guardcolumn SuperHZ-L+ Column; TSKgel SuperHZM-N+ TSKgel SuperHZM-M+ TSKgel SuperH-RC (all manufactured by Tosoh Corporation, product names) Column size: 4.6 × 20 mm (guard column), 4.6 × 150 mm (column), 6.0 × 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

[0075] [Production Example 1: Production of Maleimide-Modified Polybutadiene (Component (C))] In a 2 L glass flask container equipped with a thermometer, reflux condenser, and stirring device, 33.8 parts by mass of polybutadiene (1,2-polybutadiene homopolymer, number average molecular weight (Mn) 1,200, vinyl group content = 85 mol% or more), 1.43 parts by mass of maleimide compound 1 described below, 0.0035 parts by mass of α,α'-bis(t-butylperoxy)diisopropylbenzene, and toluene as an organic solvent were added. The mixture was then reacted under a nitrogen atmosphere at 90-100°C for 5 hours with stirring to obtain a solution of maleimide-modified polybutadiene (solid content concentration: 35% by mass). The number average molecular weight (Mn) of the obtained maleimide-modified polybutadiene was 2,000.

[0076] Furthermore, GPC was measured using the method described above for the solution containing the polybutadiene and maleimide compound 1 before the reaction and for the solution after the reaction, and the peak area derived from the maleimide compound before and after the reaction was determined. Next, the vinyl group modification rate of the maleimide compound was calculated using the following formula. The vinyl group modification rate corresponds to the rate of decrease in the peak area derived from the maleimide compound due to the reaction. Vinyl group modification rate (%) = [(Peak area derived from the maleimide compound before the reaction) - (Peak area derived from the maleimide compound after the reaction)] × 100 / (Peak area derived from the maleimide compound before the reaction) The vinyl group modification rate obtained from the above formula was 40%.

[0077] [Examples 1-3, Comparative Example 1] (Preparation of Resin Composition) Each component listed in Table 1 was stirred and mixed with toluene and methyl ethyl ketone at room temperature according to the blending amounts (unit: parts by mass) listed in Table 1 to prepare a resin composition (resin varnish) with a solid content concentration of 55-65% by mass. Note that the values ​​listed in the blending composition in Table 1 refer to parts by mass in terms of solid content in the case of a solution or dispersion. (Prepreg Production) The resin composition obtained above was coated onto a glass cloth with a thickness of 0.1 mm, and then heated and dried at 130°C for 5 minutes to produce a prepreg with a solid content concentration of approximately 50% by mass derived from the resin composition. (Production of Double-Sided Copper-Clad Laminate) Four of these prepregs were stacked, and 12 μm thick copper foil (Rz: 0.6 μm on the M side (matte side)) was placed above and below them so that the M side was in contact with the prepreg. This laminate was heated and pressure-molded under the conditions of 230°C, 3.0 MPa, and 90 minutes to produce a double-sided copper-clad laminate (thickness: 0.41 mm).

[0078] [Measurement Method] (1) Relative permittivity (Dk) - Transmission loss A double-sided copper-clad laminate A obtained in each example was immersed in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Company, Inc.), which is a copper etching solution, to remove the copper foil. From this evaluation substrate, a 40 mm x 50 mm evaluation substrate was prepared. Using this evaluation substrate, the relative permittivity (Dk) was measured at 25°C in the 10 GHz band using a "PNA Network Analyzer N5227A" (manufactured by Agilent Technologies) equipped with a split post dielectric resonator (SPDR). From the viewpoint of low transmission loss, a relative permittivity (Dk) of 3.48 or less is preferable.

[0079] (2) From the evaluation substrates obtained in each example of flame retardancy, which had their copper foil removed by immersing them in a 10% by mass solution of ammonium persulfate (a copper etching solution), test pieces measuring 127 mm in length and 12.7 mm in width (thickness: 0.41 mm) were cut out, and the flame retardancy was tested and evaluated using these test pieces in accordance with the UL94 test method (V method). Specifically, the lower end of the vertically held test piece was subjected to two 10-second flame applications using a 20 mm flame. The evaluation was performed according to the criteria of the UL94 V method.

[0080] (3) Minimum melt viscosity Approximately 0.6 g of resin powder in the B-stage state, obtained by kneading the prepreg prepared in each example, was weighed and molded into a 20 mm diameter disc-shaped tablet using a tablet molder. Using this tablet as a measurement sample, the melt viscosity was measured using a rheometer (manufactured by Rheometric, trade name "ARES-2K STD-FCO-STD") under the conditions of a heating rate of 3°C / min, a load of 0.2 N, and a temperature range of 50 to 200°C, and the minimum melt viscosity was obtained.

[0081]

[0082] In addition, the total content of components (X) and (Y) in each example in Table 1 has been adjusted so that the content of components (A) to (C) is the same in each example, assuming a total amount of 100 parts by mass.

[0083] The details of the components in Table 1 are as follows: [Component (A)] Maleimide compound 1: Indane ring-containing aromatic bismaleimide (number average molecular weight: 1,200) Maleimide compound 2: Maleimide compound "MIR-3000" (manufactured by Nippon Kayaku Co., Ltd., trade name) having a biphenyl aralkyl skeleton

[0084] [Component (X)] • Metal phosphate salt 1; Aluminum tris(diethylphosphinate) (see structural formula below);

[0085] [Component (Y)] Phosphazene compound 1: "Rabitol FP-300B" (manufactured by Fushimi Pharmaceutical Co., Ltd.), a phosphazene compound having the following structure (melting point: 77°C) (In the above structural formula, n1 represents 3 or 4.)

[0086] • Phosphazene compound 2; "Rabitol FP-100B" (manufactured by Fushimi Pharmaceutical Co., Ltd.), a phosphazene compound having the following structure (melting point: 112°C), a high-purity version of the later-mentioned Rabitol FP-110B. (In the above structural formula, n² represents an integer between 3 and 20.)

[0087] • Phosphazene compound 3; "Rabitol FP-110B" (manufactured by Fushimi Pharmaceutical Co., Ltd.), a phosphazene compound having the following structure (melting point: 112°C) (In the above structural formula, n² represents an integer between 3 and 20.)

[0088] [Component (B)] Elastomer 1: SEBS "KRATON (registered trademark) MD1653", styrene content 31% by mass, number average molecular weight (Mn) = 72,100

[0089] [(C) Component] Crosslinking agent 1: Maleimide-modified polybutadiene obtained in Production Example 1

[0090] [Component (D)] Silica 1: Spherical fused silica, average particle size: 0.5 μm, 70% by mass slurry (solvent: methyl isobutyl ketone)

[0091] [(E) Components] • Curing accelerator 1: α,α'-di(t-butylperoxy)diisopropylbenzene • Curing accelerator 2: Isocyanate macuimidazole

[0092] As is clear from Table 1, the double-sided copper-clad laminates obtained in each example exhibit excellent flame retardancy, and furthermore, the minimum melt viscosity of the prepreg is low. Because the minimum melt viscosity of the prepreg is low, the double-sided copper-clad laminates obtained in each example are thought to have excellent embedding properties for resin components into circuit patterns (circuit embedding properties). In addition, because the relative permittivity (Dk) of the double-sided copper-clad laminates obtained in each example is low, it can be said that they have the characteristic of low transmission loss. On the other hand, the double-sided copper-clad laminate of Comparative Example 1 is presumed to have poor circuit embedding properties because the minimum melt viscosity of the prepreg is significantly higher.

Claims

1. A resin composition containing (A) a thermosetting resin, (X) a metal phosphate salt, and (Y) a phosphazene compound.

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

3. The resin composition according to claim 1, wherein component (X) is a metal salt of dialkylphosphinic acid.

4. The resin composition according to claim 1, wherein in component (X), the metal salt is a lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, titanium salt, or zinc salt.

5. The resin composition according to claim 1, wherein the content of component (X) is 0.5 to 10 parts by mass per 100 parts by mass of solids in the resin composition.

6. The resin composition according to claim 1, wherein the content of component (Y) is 0.5 to 10 parts by mass per 100 parts by mass of solids in the resin composition.

7. The resin composition according to claim 1, wherein the ratio of the content of component (X) to the content of component (Y) [(X) / (Y)] is 30 / 70 to 70 / 30 by mass.

8. The resin composition according to claim 1, further comprising (B) an elastomer.

9. The resin composition according to claim 1, further comprising (C) a crosslinking agent.

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

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

12. A prepreg containing the resin composition described in claim 1 or a semi-cured product of the resin composition.

13. A resin film containing the resin composition described in claim 1 or a semi-cured product of the resin composition.

14. A laminate having a cured product of the resin composition described in claim 1 or a cured product of the prepreg described in claim 12, and a metal foil.

15. A printed circuit board having a cured product of the resin composition described in claim 1.

16. A semiconductor package having a printed circuit board according to claim 15 and a semiconductor element.

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