JP7806522B2 - Resin compositions, prepregs, laminates, resin films, printed wiring boards, and semiconductor packages - Google Patents

Description

This embodiment relates to a resin composition, a prepreg, a laminate, a resin film, a printed wiring board, and a semiconductor package.

In electronic devices such as mobile communication devices typified by mobile phones, their base station equipment, servers, routers and other network infrastructure equipment, and mainframe computers, the speed and capacity of the signals they use are increasing year by year. Accordingly, the substrate materials for the printed wiring boards used in these electronic devices are required to have dielectric properties (hereinafter sometimes referred to as "high-frequency properties") that can reduce the transmission loss of high-frequency signals, i.e., low dielectric constant and low dielectric loss tangent.
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 in the field of 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.

Printed wiring boards are primarily required to have heat resistance and low thermal expansion to withstand the environment in which they are used. For this reason, resins with excellent mechanical properties, such as maleimide resins, have been used for printed wiring boards. However, because many of these resins with excellent mechanical properties contain polar groups, there is room for improvement in their high-frequency characteristics.
Therefore, for printed wiring boards that require extremely low transmission loss, hydrocarbon resins that contribute to low dielectric loss tangent, such as polybutadiene and styrene-ethylene-butylene-styrene block copolymer (SEBS), have been used (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-077786

However, while hydrocarbon-based resins such as polybutadiene and SEBS are effective in lowering the dielectric loss tangent, increasing the amount of these resins added tends to worsen flame retardancy. As a result, there are limits to how much dielectric loss tangent can be reduced using these hydrocarbon-based resins alone, and there is a need for technology that can reduce the dielectric loss tangent while maintaining flame retardancy.

In light of this current situation, the objective of this embodiment is to provide a resin composition that maintains flame retardancy while reducing the dielectric loss tangent, as well as prepregs, laminates, resin films, printed wiring boards, and semiconductor packages that use the resin composition.

As a result of investigations into solving the above problems, the inventors have found that the problems can be solved by the following embodiments [1] to [12].
[1] (A) one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof;
(B) a resin containing a structural unit derived from an aromatic vinyl compound and having an ethylenically unsaturated bond;
A resin composition comprising:
[2] The resin composition according to the above [1], wherein the ethylenically unsaturated bond of the component (B) is contained in a 1,2-vinyl group derived from 1,3-butadiene.
[3] The resin composition according to the above [1] or [2], wherein the structural unit derived from the aromatic vinyl compound is a structural unit derived from styrene.
[4] The resin composition according to any one of the above [1] to [3], wherein the component (B) is a styrene-butadiene-styrene block copolymer.
[5] The resin composition according to any one of [1] to [4] above, wherein the number average molecular weight (Mn) of the component (B) is 5,000 to 60,000.
[6] The resin composition according to any one of the above [1] to [5], further comprising (C) one or more selected from the group consisting of conjugated diene polymers and modified conjugated diene polymers.
[7] The resin composition according to any one of the above [1] to [6], further comprising (D) a styrene-ethylene-butylene-styrene block copolymer.
[8] A prepreg containing the resin composition according to any one of [1] to [7] above or a semi-cured product of the resin composition.
[9] A laminate having a cured product of the resin composition according to any one of [1] to [7] above or a cured product of the prepreg according to [8] above, and a metal foil.
[10] A resin film containing the resin composition according to any one of [1] to [7] above or a semi-cured product of the resin composition.
[11] 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 [7] above, a cured product of the prepreg according to [8] above, and a laminate according to [9] above.
[12] A semiconductor package comprising the printed wiring board according to [11] above and a semiconductor element.

According to this embodiment, it is possible to provide a resin composition that maintains flame retardancy while reducing the dielectric loss tangent, as well as prepregs, laminates, resin films, printed wiring boards, and semiconductor packages that use the resin composition.

In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively.
For example, the expression "X to Y" (X and Y are real numbers) means a range of values equal to or greater than X and equal to or less than Y. In this specification, the expression "equal to or greater than X" means X and a value greater than X. In this specification, the expression "equal to or less than Y" means Y and a value less than Y.
The lower and upper limits of any numerical range described herein may be combined with any lower or upper limit of any other numerical range.
In the numerical ranges described in this specification, the lower or upper limit of the numerical range may be replaced with values shown in the examples.

Unless otherwise specified, each of the components and materials exemplified in this specification may be used alone or in combination of two or more.
In this specification, the content of each component in a resin composition means the total amount of the multiple substances present in the resin composition, unless otherwise specified, when multiple substances corresponding to each component are present in the resin composition.

In this specification, "solids" refers to non-volatile components excluding volatile substances such as solvents. In other words, "solids" refers to components that remain without volatilizing when the resin composition is dried, and includes those that are liquid, syrup-like, or waxy at room temperature. Here, in this specification, room temperature means 25°C.

In this specification, "(meth)acrylate" means "acrylate" and its corresponding "methacrylate." Similarly, "(meth)acrylic" means "acrylic" and its corresponding "methacrylic," and "(meth)acryloyl" means "acryloyl" and its corresponding "methacryloyl."

The number average molecular weight (Mn) in this specification refers to a value measured in polystyrene equivalent terms using gel permeation chromatography (GPC). Specifically, the number average molecular weight (Mn) in this specification can be measured by the method described in the Examples.

In this specification, "semi-cured product" is synonymous with a resin composition in the B-stage state as defined in JIS K 6800 (1985), and "cured product" is synonymous with a resin composition in the C-stage state as defined in JIS K 6800 (1985).

The mechanism of action described in this specification is speculative and does not limit the mechanism by which the effects of this embodiment are achieved.

This embodiment also includes any combination of the features described in this specification.

[Resin composition]
The resin composition of the present embodiment is
(A) one or more types selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof [hereinafter, sometimes referred to as "(A) maleimide-based resin"],
(B) a resin containing a structural unit derived from an aromatic vinyl compound and having an ethylenically unsaturated bond;
The resin composition contains:
In this specification, each component may be abbreviated as component (A), component (B), etc., and similar abbreviations may be used for other components.

<(A) Maleimide Resin>
The maleimide resin (A) is at least one selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives of such maleimide resins.
The maleimide resin (A) may be used alone or in combination of two or more.

In the following description, a maleimide resin having one or more N-substituted maleimide groups may be referred to as a "maleimide resin (AX)" or a "(AX) component."
Furthermore, a maleimide resin derivative having one or more N-substituted maleimide groups may be referred to as a "maleimide resin derivative (AY)" or "(AY) component."

(Maleimide resin (AX))
The maleimide resin (AX) is not particularly limited as long as it is a maleimide resin having one or more N-substituted maleimide groups.
From the viewpoints of conductor adhesion and heat resistance, the maleimide resin (AX) is preferably an aromatic maleimide resin having two or more N-substituted maleimide groups, and more preferably an aromatic bismaleimide resin having two N-substituted maleimide groups.

In this specification, "aromatic maleimide resin" refers to a compound having an N-substituted maleimide group directly bonded to an aromatic ring. In addition, in this specification, "aromatic bismaleimide resin" refers to a compound having two N-substituted maleimide groups directly bonded to an aromatic ring. In addition, in this specification, "aromatic polymaleimide resin" refers to a compound having three or more N-substituted maleimide groups directly bonded to an aromatic ring. In addition, in this specification, "aliphatic maleimide resin" refers to a compound having an N-substituted maleimide group directly bonded to an aliphatic hydrocarbon.

The maleimide resin (AX) is preferably a maleimide resin represented by the following general formula (A-1):

(In the formula, X ^A1 is a divalent organic group.)

X ^A1 in the above general formula (A-1) is a divalent organic group.
Examples of the divalent organic group represented by X ^A1 in the above general formula (A-1) include a divalent organic group represented by the following general formula (A-2), a divalent organic group represented by the following general formula (A-3), a divalent organic group represented by the following general formula (A-4), a divalent organic group represented by the following general formula (A-5), a divalent organic group represented by the following general formula (A-6), and a divalent organic group represented by the following general formula (A-7).

(In the formula, R ^A1 is an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. n ^A1 is an integer of 0 to 4. * represents a bonding site.)

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^A1 in general formula (A-2) above include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms; and alkynyl groups having 2 to 5 carbon atoms. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched. As the aliphatic hydrocarbon group having 1 to 5 carbon atoms, 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.
Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.
In the above general formula (A-2), n ^A1 is an integer of 0 to 4, and from the viewpoint of availability, is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.
When n ^A1 is an integer of 2 or more, the multiple R ^A1 may be the same or different.

(In the formula, R ^A2 and R ^A3 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^A2 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, a single bond, or a divalent organic group represented by the following general formula (A-3-1). ^{n A2} and n ^A3 each independently represent an integer of 0 to 4. * represents a bonding site.)

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^A2 and R ^A3 in general formula (A-3) above include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms; and alkynyl groups having 2 to 5 carbon atoms. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched. As the aliphatic hydrocarbon group having 1 to 5 carbon atoms, 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 or an ethyl group is even more preferred.
Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^A2 in general formula (A-3) above include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. The alkylene group having 1 to 5 carbon atoms is preferably an alkylene group having 1 to 3 carbon atoms, more preferably an alkylene group having 1 or 2 carbon atoms, and even more preferably a methylene group.

Examples of the alkylidene group having 2 to 5 carbon atoms represented by X ^A2 in the above general formula (A-3) include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. Among these, an alkylidene group having 2 to 4 carbon atoms is preferred, an alkylidene group having 2 or 3 carbon atoms is more preferred, and an isopropylidene group is even more preferred.

In the general formula (A-3), n ^A2 and n ^A3 each independently represent an integer of 0 to 4.
When n ^A2 or n ^A3 is an integer of 2 or greater, a plurality of R ^A2s or a plurality of R ^A3s may be the same or different.

The divalent organic group represented by X ^A2 in the general formula (A-3) and represented by the general formula (A-3-1) is as follows:

(In the formula, R ^A4 and R ^A5 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^A3 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. n ^A4 and n ^A5 each independently represent an integer of 0 to 4. * represents a bonding site.)

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^A4 and R ^A5 in general formula (A-3-1) above include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms; and alkynyl groups having 2 to 5 carbon atoms. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched. As the aliphatic hydrocarbon group having 1 to 5 carbon atoms, 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.
Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^A3 in general formula (A-3-1) above include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. The alkylene group having 1 to 5 carbon atoms is preferably an alkylene group having 1 to 3 carbon atoms, more preferably an alkylene group having 1 or 2 carbon atoms, and even more preferably a methylene group.

Examples of the alkylidene group having 2 to 5 carbon atoms represented by X ^A3 in general formula (A-3-1) above include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. Among these, an alkylidene group having 2 to 4 carbon atoms is preferred, an alkylidene group having 2 or 3 carbon atoms is more preferred, and an isopropylidene group is even more preferred.

In the general formula (A-3-1), n ^A4 and n ^A5 each independently represent an integer of 0 to 4, and from the viewpoint of availability, each is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.
When n ^A4 or n ^A5 is an integer of 2 or greater, a plurality of R ^A4s or a plurality of R ^A5s may be the same or different.

As X ^A2 in the above general formula (A-3), among the above options, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, or a divalent organic group represented by the above general formula (A-3-1) is preferable, an alkylene group having 1 to 5 carbon atoms is more preferable, and a methylene group is even more preferable.

(In the formula, n ^A6 is an integer of 0 to 10. * represents a binding site.)

In view of availability, n ^A6 in the above general formula (A-4) is preferably an integer of 0 to 5, more preferably an integer of 0 to 4, and even more preferably an integer of 0 to 3.

(In the formula, n ^A7 is a number from 0 to 5. * represents a binding site.)

(In the formula, R ^A6 and R ^A7 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms. n ^A8 represents an integer of 1 to 8. * represents a bonding site.)

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by ^R and ^R in general formula (A-6) above include alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms; and alkynyl groups having 2 to 5 carbon atoms. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched.
In the general formula (A-6), n ^A8 is an integer of 1 to 8, preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and even more preferably 1. When n ^A8 is an integer of 2 or greater, multiple R ^A6s or multiple R ^A7s may be the same or different.

(In the formula, R ^A8 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 n ^A9 represents an integer of 0 to 3. R ^A9 to R ^A11 each independently represent an alkyl group having 1 to 10 carbon atoms. R ^A12 each independently represent 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. n Each ^A10 is independently an integer of 0 to 4, and n ^A11 is a number of 0.95 to 10.0. * represents a binding site.

Examples of the alkyl group having 1 to 10 carbon atoms represented by ^R in general formula (A-7) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, etc. These alkyl groups may be linear or branched.
Examples of the alkyl group contained in the alkyloxy group having 1 to 10 carbon atoms and the alkylthio group having 1 to 10 carbon atoms represented by R ^A8 include the same alkyl groups as those having 1 to 10 carbon atoms described above.
Examples of the aryl group having 6 to 10 carbon atoms represented by R ^A8 include a phenyl group and a naphthyl group.
Examples of the aryl group contained in the aryloxy group having 6 to 10 carbon atoms and the arylthio group having 6 to 10 carbon atoms represented by R ^A8 include the same as the aryl group having 6 to 10 carbon atoms described above.
Examples of the cycloalkyl group having 3 to 10 carbon atoms represented by R ^A8 include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclodecyl group.
When n ^A9 in the above general formula (A-7) is an integer of 1 to 3, R ^A8 is preferably an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms, from the viewpoint of solvent solubility and reactivity.

Examples of the alkyl group having 1 to 10 carbon atoms represented by R ^A9 to R ^A11 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group. These alkyl groups may be either linear or branched. Among these, R ^A9 to R ^A11 are preferably alkyl groups having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, and even more preferably a methyl group.
In the general formula (A-7), n ^A9 is an integer of 0 to 3, and when n ^A9 is 2 or 3, multiple R ^A8 may be the same or different.

Among the above, the divalent organic group represented by the general formula (A-7) is preferably a divalent organic group in which n ^A9 is 0 and R ^A9 to R ^A11 are methyl groups, from the viewpoints of compatibility with other resins, solvent solubility, dielectric properties, adhesion to conductors, and ease of production.

In the general formula (A-7), a plurality of R ^A8 's, a plurality of R ^A12 's, a plurality of n ^A9 's, and a plurality of n ^A10's may be the same or different from each other. When n ^A11 is greater than 1, a plurality of R ^A9's , a plurality of R ^A10 's, and a plurality of R ^A11 's may be the same or different from each other.

The explanation about the ^alkyl group having 1 to 10 carbon atoms, the alkyloxy group having 1 to 10 carbon atoms, the alkylthio group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, the aryloxy group having 6 to 10 carbon atoms, the arylthio group having 6 to 10 carbon atoms, and the cycloalkyl group having 3 to 10 carbon atoms, represented by R in general formula ^(A-7) , is the same as the explanation about the alkyl group having 1 to 10 carbon atoms, the alkyloxy group having 1 to 10 carbon atoms, the alkylthio group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, the aryloxy group having 6 to 10 carbon atoms, the arylthio group having 6 to 10 carbon atoms, and the cycloalkyl group having 3 to 10 carbon atoms, represented by R above.
Among these, from the viewpoints of compatibility with other resins, solvent solubility, dielectric properties, adhesion to conductors, and ease of production, R ^A12 is preferably an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.
In the general formula (A-7), n ^A10 is an integer of 0 to 4, and from the viewpoints of compatibility with other resins, solvent solubility, dielectric properties, adhesion to conductors, and ease of production, is preferably an integer of 0 to 3, more preferably 0 or 2.
When n ^A10 is 1 or greater, the benzene ring and the N-substituted maleimide group have a twisted conformation, and intermolecular stacking is suppressed, which tends to further improve solvent solubility. From the same viewpoint, when n ^A10 is 1 or greater, the substitution position of R ^A12 is preferably the ortho position relative to the N-substituted maleimide group.
In the above general formula (A-7), n ^A11 is preferably 0.98 to 8.0, more preferably 1.0 to 7.0, and even more preferably 1.1 to 6.0, from the viewpoints of compatibility with other resins, solvent solubility, melt viscosity, handleability, and heat resistance.

Preferred examples of the divalent organic group represented by the above general formula (A-7) include a divalent organic group represented by the following general formula (A-7-1), a divalent organic group represented by the following general formula (A-7-2), a divalent organic group represented by the following general formula (A-7-3), and a divalent organic group represented by the following general formula (A-7-4).

(In the formula, n ^A11 is the same as in the above general formula (A-7). * represents a bonding site.)

Among the maleimide resins represented by the general formula (A-1) above, a maleimide resin having a divalent organic group represented by the general formula (A-3) above as X ^A1 [hereinafter, may be referred to as "maleimide resin (A1)"] and a maleimide resin having a divalent organic group represented by the general formula (A-7) above as X ^A1 [hereinafter, may be referred to as "maleimide resin (A2)"] are preferred, and it is more preferred to use the maleimide resin (A1) and the maleimide resin (A2) in combination.
When the maleimide resin (A1) and the maleimide resin (A2) are used in combination, the content ratio of the maleimide resin (A1) to the maleimide resin (A2) [(A1):(A2)] is not particularly limited, but from the viewpoints of dielectric properties and low thermal expansion, it is preferably 10:90 to 50:50, more preferably 15:85 to 40:60, and even more preferably 20:80 to 30:70, on a mass basis.

Examples of the maleimide resin (AX) include aromatic bismaleimide resins, aromatic polymaleimide resins, and aliphatic maleimide resins, and among these, aromatic bismaleimide resins are preferred.
Specific examples of the maleimide resin (AX) include N,N'-ethylene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-(1,3-phenylene) bismaleimide, N,N'-[1,3-(2-methylphenylene)] bismaleimide, N,N'-[1,3-(4-methylphenylene)] bismaleimide, N,N'-(1,4-phenylene) bismaleimide, bis(4-maleimidophenyl)methane, bis(3-methyl-4-maleimidophenyl)methane, ... ,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, bis(4-maleimidophenyl) ether, bis(4-maleimidophenyl) sulfone, bis(4-maleimidophenyl) sulfide, bis(4-maleimidophenyl) ketone, bis(4-maleimidocyclohexyl)methane, 1,4-bis(4-maleimidophenyl)cyclohexane, 1,4-bis(maleimidomethyl)cyclohexane, 1,4-bis(maleimidomethyl)benzene , 1,3-bis(4-maleimidophenoxy)benzene, 1,3-bis(3-maleimidophenoxy)benzene, bis[4-(3-maleimidophenoxy)phenyl]methane, bis[4-(4-maleimidophenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,2-bis[4- (4-maleimidophenoxy)phenyl]ethane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[ 4-(4-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4-bis(3-maleimidophenoxy)biphenyl, 4,4-bis(4-maleimidophenoxy)biphenyl, bis[4-(3-maleimidophenoxy)phenyl]ketone, bis[4-(4-maleimidophenoxy)phenyl]ketone, bis(4-maleimidophenyl)disulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfide, bis[4-( 4-maleimidophenoxy)phenyl] sulfide, bis[4-(3-maleimidophenoxy)phenyl] sulfoxide, bis[4-(4-maleimidophenoxy)phenyl] sulfoxide, bis[4-(3-maleimidophenoxy)phenyl] sulfone, bis[4-(4-maleimidophenoxy)phenyl] sulfone, bis[4-(3-maleimidophenoxy)phenyl] ether, bis[4-(4-maleimidophenoxy)phenyl] ether, 1,4-bis[4-(4 -maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3- Examples of the bismaleimide resin include bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, polyphenylmethane maleimide, aromatic bismaleimide resins having an indane skeleton, biphenylaralkyl maleimide resins, etc. Among these, aromatic bismaleimide resins having an indane skeleton and 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide are preferred, and it is more preferred to use an aromatic bismaleimide resin having an indane skeleton and 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide in combination.

(Maleimide resin derivative (AY))
The maleimide resin derivative (AY) is preferably an aminomaleimide resin containing a structural unit derived from the above-mentioned maleimide resin (AX) and a structural unit derived from a diamine compound.

Examples of the structural unit derived from the maleimide resin (AX) contained in the aminomaleimide resin include a structural unit formed by a Michael addition reaction between at least one N-substituted maleimide group among the N-substituted maleimide groups contained in the maleimide resin (AX) and an amino group contained in a diamine compound.
The structural unit derived from the maleimide resin (AX) contained in the aminomaleimide resin may be of one type alone or may be of two or more types.

Examples of the structural unit derived from a diamine compound contained in the aminomaleimide resin include a structural unit formed by a Michael addition reaction between one or both of two amino groups contained in the diamine compound and an N-substituted maleimide group contained in the maleimide resin (AX).
The structural unit derived from the diamine compound contained in the aminomaleimide resin may be of one type alone or may be of two or more types.

Examples of the diamine compound include 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'- Diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis(3-aminophenoxy)benzene , 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 1,4-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline aromatic diamine compounds such as 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 3,3'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, and 9,9-bis(4-aminophenyl)fluorene; and silicone compounds having two primary amino groups.
In this specification, the term "aromatic diamine compound" means a compound having two amino groups directly bonded to an aromatic ring.

((A) Content of Maleimide Resin)
The content of the maleimide resin (A) in the resin composition of the present embodiment is not particularly limited, but is preferably 5 to 90 mass %, more preferably 10 to 60 mass %, and even more preferably 15 to 40 mass %, relative to the total amount (100 mass %) of resin components in the resin composition of the present embodiment.
When the content of the (A) maleimide resin is equal to or greater than the above lower limit, the heat resistance, moldability, processability, and conductor adhesion tend to be improved. When the content of the (A) maleimide resin is equal to or less than the above upper limit, the dielectric properties tend to be improved.

In this specification, the term "resin component" refers to a resin and a compound that forms a resin through a curing reaction.
For example, in the resin composition of the present embodiment, the component (A) and the component (B) correspond to the resin component.
When the resin composition of the present embodiment contains, as optional components, a resin or a compound that forms a resin by a curing reaction in addition to the above components, these optional components are also included in the resin component. Examples of optional components corresponding to the resin component include component (C) and component (D), which will be described later.
On the other hand, components (E), (F) and (G) are not included in the resin component.

The total content of the resin components in the resin composition of this embodiment is not particularly limited, but from the viewpoints of low thermal expansion, heat resistance, flame retardancy, and conductor adhesion, it is preferably 20 to 70% by mass, more preferably 25 to 60% by mass, and even more preferably 30 to 50% by mass relative to the total solids content (100% by mass) of the resin composition of this embodiment.

<(B) Resin containing a structural unit derived from an aromatic vinyl compound and having an ethylenically unsaturated bond>
The component (B) is a resin containing a structural unit derived from an aromatic vinyl compound and having an ethylenically unsaturated bond.
The resin composition of this embodiment can reduce the dielectric loss tangent while maintaining flame retardancy by containing component (B). This is presumably because component (B) has low polarity, which contributes to reducing the dielectric loss tangent, and also contains aromatic rings that are less flammable than aliphatic hydrocarbons, and the ethylenically unsaturated bonds exhibit a radical trapping effect that captures macroradicals generated by decomposition upon combustion.
The component (B) may be used alone or in combination of two or more.

The structural unit derived from an aromatic vinyl compound contained in component (B) is preferably a structural unit derived from a styrene-based compound represented by the following general formula (B-1):

(In the formula, R ^B1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ^B2 is an alkyl group having 1 to 5 carbon atoms, and n ^B1 is an integer of 0 to 5.)

Examples of the alkyl group having 1 to 5 carbon atoms represented by R ^B1 and R ^B2 in the above general formula (B-1) 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, and an n-pentyl group. The alkyl group having 1 to 5 carbon atoms may be either linear or branched. 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. n ^B1 in the above general formula (B-1) is an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

Among the structural units shown above, from the viewpoint of flame retardancy, the structural unit derived from an aromatic vinyl compound contained in component (B) is preferably a structural unit derived from styrene.

The content of structural units derived from aromatic vinyl compounds in component (B) is not particularly limited, but from the viewpoint of dielectric properties and flame retardancy, it is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass of all structural units.

The component (B) has an ethylenically unsaturated bond.
In this specification, the term "ethylenically unsaturated bond" means a carbon-carbon double bond capable of undergoing an addition reaction, and does not include double bonds in aromatic rings.
Examples of ethylenically unsaturated bonds include those contained in a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, a (meth)acryloyl group, a 2-butenylene group, and the like.

The number of ethylenically unsaturated bonds contained in one molecule of component (B) is not particularly limited, but is preferably 2 or more, more preferably 10 or more, and even more preferably 20 or more.

The component (B) is preferably a copolymer resin having a structural unit derived from an aromatic vinyl compound and a structural unit having an ethylenically unsaturated bond.
From the viewpoint of improving flame retardancy, the component (B) preferably has a vinyl group as the group containing an ethylenically unsaturated bond.
When component (B) has a vinyl group, the vinyl group is preferably a vinyl group derived from a conjugated diene compound. That is, component (B) preferably contains a structural unit derived from a conjugated diene compound, and the structural unit preferably has a vinyl group in a side chain.
Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, etc. The structural unit derived from the conjugated diene compound may be one type alone or two or more types.
Among these, the ethylenically unsaturated bond contained in component (B) is preferably one contained in a 1,2-vinyl group derived from 1,3-butadiene.
The 1,2-vinyl group derived from 1,3-butadiene is a vinyl group contained in a structural unit represented by the following formula (B-2).

When component (B) contains structural units derived from a conjugated diene compound, the content of structural units derived from a conjugated diene compound having a vinyl group in a side chain relative to all structural units derived from the conjugated diene compound is not particularly limited, but from the viewpoints of compatibility with other resins, dielectric properties, low thermal expansion, and heat resistance, it is preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 85 mol % or more.
There is no particular upper limit to the content of structural units derived from a conjugated diene compound having a vinyl group in a side chain, and the content may be 100 mol % or less, 97 mol % or less, or 95 mol % or less, based on all structural units derived from a conjugated diene compound.

When component (B) contains structural units derived from a conjugated diene compound, the content of structural units derived from a conjugated diene compound in component (B) is not particularly limited, but from the viewpoints of dielectric properties and flame retardancy, it is preferably 20 to 80 mass%, more preferably 30 to 70 mass%, and even more preferably 40 to 60 mass% of all structural units.

When component (B) contains structural units derived from a conjugated diene compound, some of the structural units derived from the conjugated diene compound may be hydrogenated, but it is preferable that they are not hydrogenated.
From the viewpoint of flame retardancy, the hydrogenation rate of the carbon-carbon double bonds contained in the structural units derived from the conjugated diene compound contained in component (B) is preferably 0 to 10%, more preferably 0 to 5%, and even more preferably 0 to 1%.

Component (B) may or may not contain structural units other than structural units derived from aromatic vinyl compounds and structural units derived from conjugated diene compounds.

The number average molecular weight (Mn) of component (B) is not particularly limited, but from the perspective of maintaining the melt viscosity of the resin composition in an appropriate range, it is preferably 5,000 to 60,000, more preferably 10,000 to 40,000, and even more preferably 15,000 to 25,000.

Examples of component (B) include styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS). Of these, styrene-butadiene-styrene block copolymer (SBS) is preferred from the standpoints of dielectric properties and flame retardancy.

(Content of component (B))
The content of component (B) in the resin composition of the present embodiment is not particularly limited, but is preferably 1 to 40 mass%, more preferably 5 to 30 mass%, and even more preferably 8 to 25 mass%, relative to the total amount (100 mass%) of the resin components in the resin composition of the present embodiment.
When the content of component (B) is equal to or greater than the lower limit, the dielectric properties tend to be better, and when the content of component (B) is equal to or less than the upper limit, the heat resistance tends to be better.

<(C) One or more polymers selected from the group consisting of conjugated diene polymers and modified conjugated diene polymers>
From the viewpoint of dielectric properties, the resin composition of the present embodiment preferably further contains (C) one or more polymers selected from the group consisting of conjugated diene polymers and modified conjugated diene polymers.
The component (C) may be used alone or in combination of two or more.

(Conjugated diene polymer)
In this specification, the term "conjugated diene polymer" means a polymer of a conjugated diene compound.
The resin composition of the present embodiment tends to have better dielectric properties due to the inclusion of a conjugated diene polymer.

Examples of conjugated diene compounds that are monomer components of conjugated diene polymers 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 kind of conjugated diene compound, or may be a copolymer of two or more kinds of conjugated diene compounds.
The conjugated diene polymer may also be a copolymer of one or more conjugated diene compounds and one or more monomers other than the conjugated diene compounds.
When the conjugated diene polymer is a copolymer, the polymerization mode is not particularly limited, and may be any of random polymerization, block polymerization, and graft polymerization.

As the conjugated diene polymer, a conjugated diene polymer having a vinyl group in the side chain is preferred from the viewpoint of compatibility with other resins and dielectric properties.
The number of side chain vinyl groups that the conjugated diene polymer has in one molecule is not particularly limited, but from the viewpoints of compatibility with other resins and dielectric properties, it is preferably 2 or more, more preferably 5 or more, and even more preferably 10 or more.
The upper limit of the number of side chain vinyl groups that the conjugated diene polymer has in one molecule is not particularly limited, but may be, for example, 100 or less, 80 or less, or 60 or less.

Examples of conjugated diene polymers include polybutadiene having a vinyl group and polyisoprene having a vinyl group. Among these, from the viewpoints of dielectric properties and heat resistance, polybutadiene having a vinyl group is preferred, and polybutadiene having a 1,2-vinyl group derived from 1,3-butadiene is more preferred. Furthermore, as polybutadiene having a 1,2-vinyl group derived from 1,3-butadiene, polybutadiene homopolymer having a 1,2-vinyl group derived from 1,3-butadiene is preferred.
The 1,2-vinyl group derived from 1,3-butadiene contained in the conjugated diene polymer is a vinyl group contained in a structural unit represented by the following formula (C-1).

When the conjugated diene polymer 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, dielectric properties, and heat resistance, it is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 85 mol% or more. There is also no particular upper limit to the vinyl group content, and it may be 100 mol% or less, 95 mol% or less, or 90 mol% or less. As the structural unit having a 1,2-vinyl group, a structural unit represented by the above formula (C-1) is preferred.
From the same viewpoint, the polybutadiene having a 1,2-vinyl group is preferably a 1,2-polybutadiene homopolymer.

The number average molecular weight (Mn) of the conjugated diene polymer is not particularly limited, but from the viewpoints of compatibility with other resins, dielectric properties, and heat resistance, it is preferably 400 to 3,000, more preferably 600 to 2,000, and even more preferably 800 to 1,500.

(Modified conjugated diene polymer)
The modified conjugated diene polymer is a polymer obtained by modifying a conjugated diene polymer.
The resin composition of the present embodiment contains a modified conjugated diene polymer, and thus tends to have good heat resistance and low thermal expansion, while also being more likely to have excellent dielectric properties.

From the viewpoints of compatibility with other resins, dielectric properties, and conductor adhesion, a preferred modified conjugated diene polymer is one obtained by modifying a conjugated diene polymer having a vinyl group in the side chain with a maleimide resin having two or more N-substituted maleimide groups.

As the conjugated diene polymer having a vinyl group in the side chain, for example, the conjugated diene polymer having a vinyl group in the side chain explained as the conjugated diene polymer can be used, and the same applies to the preferred embodiment.
The conjugated diene polymer having a vinyl group in the side chain may be used alone or in combination of two or more.

As the maleimide resin having two or more N-substituted maleimide groups, for example, the maleimide resin having two or more N-substituted maleimide groups explained as the maleimide resin (AX) can be used, and preferred embodiments are also the same.
The maleimide resin having two or more N-substituted maleimide groups may be used alone or in combination of two or more.

The modified conjugated diene polymer preferably has a substituent in its side chain that is formed by a reaction between a side-chain vinyl group of a conjugated diene polymer having a vinyl group in its side chain and an N-substituted maleimide group of a maleimide resin having two or more N-substituted maleimide groups [hereinafter, this may be referred to as a "maleimide resin-derived substituent"].
From the viewpoints of compatibility with other resins, dielectric properties, low thermal expansion, and heat resistance, the maleimide resin-derived substituent is preferably a group containing a structure represented by the following general formula (C-2) or (C-3), as a structure derived from a maleimide resin having two or more N-substituted maleimide groups:

(In the formula, X ^C1 is a divalent group obtained by removing two N-substituted maleimide groups from a maleimide resin having two or more N-substituted maleimide groups, * ^C1 is a moiety bonding to a carbon atom derived from a side chain vinyl group of a conjugated diene polymer having a vinyl group in the side chain, and * ^C2 is a moiety bonding to another atom.)

The modified conjugated diene polymer preferably has a maleimide resin-derived substituent and a vinyl group in the side chain.
The vinyl group contained in the modified conjugated diene polymer is preferably a 1,2-vinyl group derived from 1,3-butadiene.

The number average molecular weight (Mn) of the modified conjugated diene polymer is not particularly limited, but from the viewpoints of compatibility with other resins, dielectric properties, low thermal expansion, and heat resistance, it is preferably 700 to 6,000, more preferably 800 to 5,000, and even more preferably 1,000 to 2,500.

The modified conjugated diene polymer can be produced by reacting a conjugated diene polymer having a vinyl group in the side chain with a maleimide resin having two or more N-substituted maleimide groups.
The method for reacting a conjugated diene polymer having a vinyl group in a side chain with a maleimide resin having two or more N-substituted maleimide groups is not particularly limited. For example, a modified conjugated diene polymer can be obtained by charging a conjugated diene polymer having a vinyl group in a side chain, a maleimide resin having two or more N-substituted maleimide groups, a reaction catalyst, and an organic solvent into a reaction vessel and reacting them while heating, keeping the temperature, stirring, etc. as necessary.

When carrying out the above reaction, the ratio (M m /M _v ) of the number of moles (M m ) _of N _{-substituted maleimide groups in the maleimide resin having two or more N-substituted maleimide groups to the number of moles (M v ) of} side chain vinyl groups in the conjugated diene polymer having vinyl groups in the side chains is not particularly limited, but is preferably 0.001 to 0.5, more preferably 0.005 to 0.1, and even more preferably 0.008 to 0.05, from the viewpoints of compatibility of the resulting modified conjugated diene polymer with other resins and suppression of gelation of the product during the reaction.

(Content of component (C))
When the resin composition of the present embodiment contains the component (C), the content of the component (C) is not particularly limited, but is preferably 5 to 40 mass %, more preferably 10 to 30 mass %, and even more preferably 15 to 25 mass %, relative to the total amount (100 mass %) of the resin components in the resin composition of the present embodiment.
When the content of component (C) is equal to or greater than the lower limit, the dielectric properties tend to be better, and when the content of component (C) is equal to or less than the upper limit, the heat resistance and flame retardancy tend to be better.

<(D) Styrene-Ethylene-Butylene-Styrene Block Copolymer>
From the viewpoint of dielectric properties, the resin composition of the present embodiment preferably further contains (D) a styrene-ethylene-butylene-styrene block copolymer [hereinafter, sometimes referred to as "(D) SEBS"].
(D) SEBS may be used alone or in combination of two or more.

(D) SEBS is obtained by completely hydrogenating the carbon-carbon double bonds in a styrene-butadiene-styrene block copolymer.
In (D) SEBS, the content of structural units derived from styrene (hereinafter, may be referred to as "styrene content") is not particularly limited, but is preferably 10 to 50% by mass, more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass.

(D) Commercially available SEBS products include, for example, the Tuftec (registered trademark) H series and M series manufactured by Asahi Kasei Corporation, the Septon (registered trademark) series manufactured by Kuraray Co., Ltd., and the Kraton (registered trademark) G Polymer series manufactured by Kraton Polymer Japan Co., Ltd.

(D) The number average molecular weight (Mn) of SEBS is not particularly limited, but is preferably 10,000 to 200,000, more preferably 20,000 to 150,000, and even more preferably 30,000 to 100,000.

((D) SEBS content)
When the resin composition of the present embodiment contains (D) SEBS, the content of (D) SEBS is not particularly limited, but is preferably 10 to 80 mass %, more preferably 20 to 60 mass %, and even more preferably 30 to 50 mass %, relative to the total amount (100 mass %) of resin components in the resin composition of the present embodiment.
When the content of (D) SEBS is equal to or greater than the lower limit, the dielectric properties tend to be better, whereas when the content of (D) SEBS is equal to or less than the upper limit, the heat resistance and flame retardancy tend to be better.

<(E) Inorganic filler>
The resin composition of the present embodiment preferably further contains (E) an inorganic filler from the viewpoints of low thermal expansion, elastic modulus, heat resistance, and flame retardancy.
The inorganic filler (E) may be used alone or in combination of two or more.

Examples of (E) inorganic fillers 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, talc, aluminum borate, silicon carbide, etc. 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 precipitated silica produced by a wet method and having a high water content, and dry-process silica produced by a dry method and containing almost no bound water, etc. Furthermore, examples of dry-process silica that differ in production method include crushed silica, fumed silica, and fused silica.

The average particle size of the (E) inorganic filler is not particularly limited, but is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm, and even more preferably 0.2 to 1 μm. Here, the average particle size of the (E) inorganic filler refers to the particle size at the point corresponding to 50% volume when a cumulative frequency distribution curve of particle sizes is calculated, with the total volume of the particles being 100%. The particle size of the (E) inorganic filler can be measured using a particle size distribution measuring device using a laser diffraction scattering method, for example.
The shape of the (E) inorganic filler may be spherical, crushed, or the like, with spherical being preferred.

When the resin composition of this embodiment contains (E) an inorganic filler, a coupling agent may be used to improve the dispersibility of (E) the inorganic filler and its adhesion to the organic component. Examples of coupling agents include silane coupling agents and titanate coupling agents.

((E) Content of inorganic filler)
When the resin composition of the present embodiment contains an inorganic filler (E), the content of the inorganic filler (E) is not particularly limited, but from the viewpoints of low thermal expansion, elastic modulus, heat resistance, and flame retardancy, it is preferably 10 to 90 mass %, more preferably 20 to 80 mass %, even more preferably 30 to 70 mass %, and particularly preferably 40 to 60 mass %, relative to the total solid content (100 mass %) of the resin composition of the present embodiment.

<(F) Curing Accelerator>
From the viewpoint of improving curability, the resin composition of the present embodiment preferably further contains (F) a curing accelerator.
The curing accelerator (F) may be used alone or in combination of two or more.

Examples of the (F) curing accelerator 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 an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; phosphorus compounds such as triphenylphosphine; 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, glass transition temperature, 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.

((F) Content of curing accelerator)
When the resin composition of the present embodiment contains the curing accelerator (F), the content of the curing accelerator (F) is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the total of the resin components in the resin composition of the present embodiment.
When the content of the (F) curing accelerator is equal to or greater than the lower limit, the dielectric properties, heat resistance, adhesion to a conductor, elastic modulus, and glass transition temperature tend to be better. When the content of the (F) curing accelerator is equal to or less than the upper limit, the storage stability tends to be better.

<(G) Flame Retardant>
The resin composition of the present embodiment tends to have improved flame retardancy by containing the flame retardant (G).
The flame retardant (G) may be used alone or in combination of two or more. If necessary, a flame retardant auxiliary may also be contained.

(G) Examples of the flame retardant include phosphorus-based flame retardants, metal hydrates, and halogen-based flame retardants.
The phosphorus-based flame retardant may be an inorganic phosphorus-based flame retardant or an organic phosphorus-based flame retardant.
Examples of inorganic phosphorus-based flame retardants include red phosphorus; ammonium phosphates such as monoammonium phosphate, diammonium phosphate, triammonium phosphate, and ammonium polyphosphate; inorganic nitrogen-containing phosphorus compounds such as phosphoric acid amide; phosphoric acid; and phosphine oxide.
Examples of organic phosphorus-based flame retardants include aromatic phosphate ester compounds, mono-substituted phosphonic acid diester compounds, di-substituted phosphinic acid ester compounds, metal salts of di-substituted phosphinic acids, organic nitrogen-containing phosphorus compounds, cyclic organic phosphorus compounds, etc. Among these, aromatic phosphate ester compounds and metal salts of di-substituted phosphinic acids are preferred.
Examples of metal hydrates include aluminum hydroxide hydrate and magnesium hydroxide hydrate.
Examples of halogen-based flame retardants include chlorine-based flame retardants and bromine-based flame retardants.

((G) Flame retardant content)
When the resin composition of the present embodiment contains a flame retardant (G), the content of the flame retardant (G) is not particularly limited, but is preferably 1 to 45 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 15 to 35 parts by mass per 100 parts by mass of the total of the resin components in the resin composition of the present embodiment.
When the content of the (G) flame retardant is equal to or greater than the above lower limit, the flame retardancy tends to be better, whereas when the content of the (G) flame retardant is equal to or less than the above upper limit, the moldability, adhesion to conductors, and heat resistance tend to be better.

<Other ingredients>
The resin composition of this embodiment may further contain, as necessary, one or more additives selected from the group consisting of resin materials other than the above components, antioxidants, heat stabilizers, antistatic agents, UV absorbers, pigments, colorants, lubricants, and other additives. Each of these may be used alone or in combination of two or more. The amount of each additive is not particularly limited, and may be used as needed within a range that does not impair the effects of this embodiment.

(organic solvent)
The resin composition of the present embodiment may contain an organic solvent from the viewpoint of facilitating handling and facilitating production of a prepreg, which will be described later.
The organic solvents may be used alone or in combination of two or more.
In this specification, a resin composition containing an 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 hydrocarbon-based 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.
Among these, from the viewpoint of solubility, alcohol-based solvents, ketone-based solvents, nitrogen atom-containing solvents, and aromatic hydrocarbon-based solvents are preferred, aromatic hydrocarbon-based solvents are more preferred, and toluene is even more preferred.

<Method of producing resin composition>
The resin composition of this embodiment can be produced by mixing component (A), component (B), and other components used as needed, using a known method. At this time, each component may be dissolved or dispersed while stirring. The mixing conditions, such as the order of mixing, temperature, and time, are not particularly limited and may be set as desired depending on the type of raw materials, etc.

<Relative dielectric constant (Dk) of cured product>
The dielectric constant (Dk) at 10 GHz of the cured product of the resin composition of this embodiment is not particularly limited, but is preferably 3.5 or less, more preferably 3.4 or less, and even more preferably 3.3 or less. The smaller the dielectric constant (Dk), the better, and there is no particular restriction on the lower limit, but in consideration of the balance with other physical properties, it may be, for example, 2.4 or more, or 2.5 or more.
The above-mentioned relative dielectric constant (Dk) is a value based on the cavity resonator perturbation method, and more specifically, is a value measured by the method described in the examples.

<Dielectric loss tangent (Df) of cured product>
The dielectric loss tangent (Df) at 10 GHz of the cured product of the resin composition of this embodiment is not particularly limited, but is preferably 0.0040 or less, more preferably 0.0030 or less, and even more preferably 0.0020 or less. The smaller the dielectric loss tangent (Df), the better, and there is no particular limit to the lower limit, but in consideration of the balance with other physical properties, it may be, for example, 0.0010 or more, or 0.0011 or more.
The dielectric loss tangent (Df) is a value based on the cavity resonator perturbation method, and more specifically, is a value measured by the method described in the examples.

[Prepreg]
The prepreg of the present embodiment is a prepreg containing the resin composition of the present embodiment or a semi-cured product of the resin composition.
The prepreg of the present embodiment contains, for example, the resin composition of the present embodiment or a semi-cured product of the resin composition, and a sheet-like fiber base material.

As the sheet-like fiber base material contained in the prepreg of this embodiment, for example, a known sheet-like fiber base material used in various laminates for electrical insulating materials can be used.
Examples of the material 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 prepreg of this embodiment can be produced, for example, by impregnating or applying the resin composition of this embodiment to a sheet-like fiber substrate, and then heating and drying it to B-stage.
The temperature and time for heat drying are not particularly limited, but from the viewpoint of productivity and appropriately bringing the resin composition of the present embodiment into a B-stage, the temperature and time for heat drying can be, for example, 50 to 200°C and 1 to 30 minutes.

The solids concentration derived from the resin composition in the prepreg of this embodiment is not particularly limited, but from the viewpoint of easily achieving better moldability when formed into a laminate, it is preferably 20 to 90% by mass, more preferably 25 to 80% by mass, and even more preferably 30 to 75% by mass.

[Resin film]
The resin film of the present embodiment is a resin film containing the resin composition of the present embodiment or a semi-cured product of the resin composition.
The resin film of this embodiment can be produced, for example, by applying the resin composition of this embodiment containing an organic solvent, that is, a resin varnish, to a support and then drying it by heating.
Examples of the support include a plastic film, a metal foil, and release paper.
The temperature and time for heat drying are not particularly limited, but from the viewpoint of productivity and appropriately bringing the resin composition of this embodiment into a B-stage, the temperature and time for heat drying can be set to 50 to 200° C. and 1 to 30 minutes.

The resin film of this embodiment is preferably used to form an insulating layer when manufacturing printed wiring boards.

[Laminate]
The laminate of the present embodiment is a laminate having a cured product of the resin composition of the present embodiment or a cured product of the prepreg of the present embodiment and a metal foil.
A laminate having a metal foil is sometimes called a metal-clad laminate.

The metal for the metal foil is not particularly limited, and examples include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing one or more of these metal elements.

The laminate of this embodiment can be produced, for example, by placing metal foil on one or both sides of the prepreg of this embodiment and then molding it under heat and pressure.
Usually, the B-staged prepreg is cured by this heat and pressure molding to obtain the laminate of this embodiment.
When hot-press molding is performed, only one prepreg may be used, or two or more prepregs may be laminated.
For the hot pressure molding, for example, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like can be used.
The conditions for the hot pressing are not particularly limited, but may be, for example, a temperature of 100 to 300° C., a time of 10 to 300 minutes, and a pressure of 1.5 to 5 MPa.

[Printed wiring board]
The printed wiring board of this embodiment is a printed wiring board having one or more materials selected from the group consisting of a cured product of the resin composition of this embodiment, a cured product of the prepreg of this embodiment, and a laminate of this embodiment.
The printed wiring board of this embodiment can be produced, for example, by forming a conductor circuit on one or more materials selected from the group consisting of a cured product of the prepreg of this embodiment, a cured product of the resin film of this embodiment, and a laminate by a known method. Furthermore, a multilayer printed wiring board can also be produced by further performing a multilayer adhesive process as necessary. The conductor circuit can be formed, for example, by appropriately performing drilling, metal plating, etching of metal foil, etc.

[Semiconductor package]
The semiconductor package of this embodiment includes the printed wiring board of this embodiment and a semiconductor element.
The semiconductor package of this embodiment can be manufactured by, for example, mounting a semiconductor element, a memory, and the like on the printed wiring board of this embodiment by a known method.

The present embodiment will be described in detail below using examples. However, the present embodiment is not limited to the following examples.

In each example, the number average molecular weight (Mn) was measured by the following procedure.
(Method for measuring number average molecular weight (Mn))
The number average molecular weight (Mn) was 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.
Equipment: High-speed GPC equipment HLC-8320GPC
Detector: UV absorption detector UV-8320 [manufactured by Tosoh Corporation]
Column: Guard column: TSK Guard column Super HZ-L + column: TSKgel Super HZM-N + TSKgel Super HZM-M + TSKgel Super H-RC (all product names manufactured by Tosoh Corporation)
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: 25μL
Flow rate: 1.00mL/min Measurement temperature: 40℃

[Production of modified conjugated diene polymer]
Production Example 1
A 2 L glass flask equipped with a thermometer, a reflux condenser, and a stirrer and capable of being heated and cooled was charged with 100 parts by mass of 1,2-polybutadiene homopolymer (number average molecular weight (Mn) = 1,200, vinyl group content = 85% or more), 4.4 parts by mass of 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 0.1 parts by mass of α,α'-bis(t-butylperoxy)diisopropylbenzene, and toluene as an organic solvent. The mixture was then stirred at 90 to 100°C for 5 hours under a nitrogen atmosphere to obtain a solution of a modified conjugated diene polymer with a solids concentration of 35% by mass.

[Production of resin composition]
Examples 1 and 2, Comparative Examples 1 and 2
Each component shown in Table 1 was blended with toluene in the amounts shown in Table 1, and the blended mixture was stirred and mixed at 25°C or while heating to 50 to 80°C to prepare a resin composition with a solids concentration of approximately 50% by mass. In Table 1, the blending amount of each component is expressed in parts by mass, and in the case of a solution, it means parts by mass converted into solids content.

[Production of copper-clad laminate]
The resin composition obtained in each example was impregnated into glass cloth (manufactured by Nitto Boseki Co., Ltd., product name "NE Glass Cloth #1078") and dried by heating at 100°C for 4 minutes to obtain a prepreg. The solid content concentration derived from the resin composition in the prepreg was 64% by mass in Example 1 and Comparative Example 1, and 76% by mass in Example 2 and Comparative Example 2.
Next, ten prepregs were stacked in Example 1 and Comparative Example 1, and six prepregs were stacked in Example 2 and Comparative Example 2, and electrolytic copper foils were placed on top and bottom of each prepreg. The stack was then pressed at a pressure of 3 MPa and a temperature of 230°C for 90 minutes to obtain a copper-clad laminate.

[Evaluation and measurement methods]
The resin compositions and copper-clad laminates obtained in the above Examples and Comparative Examples were subjected to measurements and evaluations according to the following methods. The results are shown in Table 1.

(Method for measuring relative permittivity and dielectric loss tangent)
The copper foil was removed from the copper-clad laminate obtained in each example by immersing it in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Company, Inc.), which is a copper etching solution, to prepare a 2 mm × 50 mm test piece. Next, the relative permittivity (Dk) and dielectric loss tangent (Df) of the test piece were measured in the 10 GHz band at an ambient temperature of 25°C according to the cavity resonator perturbation method.

(Method for measuring melt viscosity)
The resin composition obtained in each example was applied to a 38 μm thick PET film (manufactured by Teijin Limited, product name: G2-38), and then heated and dried at 170° C. for 5 minutes to produce a B-stage resin film. This resin film was peeled off from the PET film and then pulverized to obtain a B-stage resin powder.
Approximately 0.6 g of the resin powder obtained above was weighed and molded into a disk-shaped tablet with a diameter of 20 mm using a tablet molding machine. Subsequently, using this tablet as a measurement sample, the viscosity was measured using a rheometer (manufactured by Rheometrics, product name: ARES-2K STD-FCO-STD) under conditions of a heating rate of 3°C/min, a load of 0.2 N, and a measurement temperature range of 50 to 200°C, and the minimum melt viscosity was recorded as the melt viscosity.

(Flame retardancy evaluation method)
The copper foil was removed from the copper-clad laminate obtained in each example by immersing it in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Company, Inc.), which is a copper etching solution, and the copper foil was removed, and the resulting specimen was cut into a length of 127 mm and a width of 12.7 mm. Next, in accordance with the UL94 test method (V method), a 20 mm flame was applied to the lower end of the test specimen held vertically for 10 seconds twice, and the flame retardancy was evaluated in accordance with the standards of UL94 V method.

The materials in Table 1 are as follows:
[Component (A)]
Maleimide resin 1: Aromatic bismaleimide resin containing an indane ring Maleimide resin 2: 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide

[(B) Component]
SBS: styrene-butadiene-styrene block copolymer, styrene/butadiene content ratio = 50/50 (mass basis), number average molecular weight (Mn): 20,000, manufactured by Nippon Soda Co., Ltd., trade name "1,2-SBS", the ratio of structural units having 1,2-vinyl groups to all structural units derived from butadiene is 94 mol%

[(C) Component]
Modified conjugated diene polymer: Modified conjugated diene polymer obtained in Production Example 1

[(D) Component]
SEBS: styrene-ethylene-butylene-styrene block copolymer, styrene/ethylene-butylene content ratio = 30/70 (by mass), manufactured by Kraton Corporation, trade name "MD1653MO", number average molecular weight (Mn) 46,720

The results shown in Table 1 show that when comparing Comparative Example 1, which does not contain component (B), with Example 1, in which a portion of component (A) in Comparative Example 1 is replaced with component (B), Example 1 maintains flame retardancy while having a lower dielectric tangent than Comparative Example 1. A similar effect can also be confirmed by comparing Example 2 with Comparative Example 2.

The cured product produced from the resin composition of this embodiment has a low dielectric tangent and excellent flame retardancy, so prepregs, laminates, printed wiring boards, semiconductor packages, and the like obtained using this resin composition are particularly suitable for use in electronic components that handle high-frequency signals.

Claims (12)

(A) one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof;
(B) a resin containing a structural unit derived from an aromatic vinyl compound and having an ethylenically unsaturated bond;
(D) a styrene-ethylene-butylene-styrene block copolymer;
A resin composition comprising: The resin composition according to claim 1, wherein the ethylenically unsaturated bond in component (B) is contained in a 1,2-vinyl group derived from 1,3-butadiene. The resin composition according to claim 1 or 2, wherein the structural units derived from an aromatic vinyl compound are structural units derived from styrene. The resin composition according to any one of claims 1 to 3, wherein component (B) is a styrene-butadiene-styrene block copolymer. The resin composition according to any one of claims 1 to 4, wherein the number average molecular weight (Mn) of component (B) is 5,000 to 60,000. The resin composition according to any one of claims 1 to 5, further comprising (C) one or more polymers selected from the group consisting of conjugated diene polymers and modified conjugated diene polymers. the content of the component (A) is 5 to 60% by mass relative to the total amount (100% by mass) of resin components in the resin composition,
the content of the (B) component is 1 to 40% by mass relative to the total amount (100% by mass) of resin components in the resin composition,
The content of the (D) component is 10 to 80% by mass relative to the total amount (100% by mass) of the resin components in the resin composition.
The resin composition according to any one of claims 1 to 6. A prepreg containing the resin composition according to any one of claims 1 to 7 or a semi-cured product of said resin composition. A laminate comprising a cured product of the resin composition described in any one of claims 1 to 7 or a cured product of the prepreg described in claim 8, and a metal foil. A resin film containing the resin composition according to any one of claims 1 to 7 or a semi-cured product of the resin composition. A printed wiring board comprising one or more components selected from the group consisting of a cured product of the resin composition described in any one of claims 1 to 7, a cured product of the prepreg described in claim 8, and the laminate described in claim 9. A semiconductor package comprising the printed wiring board of claim 11 and a semiconductor element.