JP7739802B2 - Resin composition, prepreg, laminate, resin film, multilayer printed wiring board, antenna device and antenna module - Google Patents

Description

This embodiment relates to a resin composition, a prepreg, a laminate, a resin film, a multilayer printed wiring board, an antenna device, and an antenna module.

In recent years, the widespread use of mobile devices such as smartphones and the advancement of technological innovations such as the Internet of Things (IoT) have led to an increase in the number of home appliances and electronic devices with wireless communication capabilities. This has led to an increase in communication traffic on wireless networks, raising concerns about a decline in communication speed and quality.
To solve this problem, the development of the fifth generation mobile communication system (hereinafter sometimes referred to as "5G") is underway and is already being put into use. 5G uses multiple antenna elements to perform advanced beamforming and spatial multiplexing, and also uses millimeter wave signals with higher frequencies of tens of GHz in addition to the conventionally used 6 GHz band signals. This is expected to increase communication speeds and improve communication quality.
On the other hand, since mobile terminals such as smartphones are required to be miniaturized, the antenna modules also need to be miniaturized, and it is widely known that in order to achieve miniaturization of the antenna module, the dielectric constant (Dk) of the substrate needs to be increased.

A method of increasing the dielectric constant (Dk) of a substrate is to add a filler having a high dielectric constant (Dk).
Patent Document 1 discloses a ceramic powder made of titanium oxide or titanate having a BET specific surface area measured by the N ₂ adsorption method in the range of 0.1 to 2.0 ^{m 2} /g and an average particle size measured by the air permeability method in the range of 0.8 to 100 μm.

International Publication No. 2010/027074

The technology described in Patent Document 1 is said to be capable of providing a ceramic powder that, when combined with a synthetic resin, can produce a dielectric composite material that exhibits a sufficiently high relative dielectric constant and a sufficiently low dielectric loss tangent.

However, research by the inventors and others has revealed that when titanium-based inorganic fillers are blended in at high ratios, solder heat resistance decreases, and improvements are desired.

In light of this current situation, the present embodiment aims to provide a resin composition containing a titanium-based inorganic filler that has excellent heat resistance, as well as prepregs, laminates, resin films, multilayer printed wiring boards, antenna devices, and antenna modules that use the resin composition.

The present inventors have conducted research to solve the above problems and have found that the problems can be solved by the present embodiment described below.
That is, this embodiment relates to the following [1] to [16].
[1] (A) a thermosetting resin;
(B) a titanium-based inorganic filler;
(C) a titanate-based coupling agent;
A resin composition comprising:
[2] The resin composition according to the above [1], wherein the average particle size (D ₅₀ ) of the titanium-based inorganic filler (B) is 0.1 to 20 μm.
[3] The resin composition according to the above [1] or [2], wherein the titanium-based inorganic filler (B) is a titanate.
[4] The resin composition according to [3] above, wherein the titanate is at least one selected from the group consisting of barium titanate, potassium titanate, calcium titanate, strontium titanate, lead titanate, and aluminum titanate.
[5] The resin composition according to any one of [1] to [4] above, which is obtained by mixing (B) a titanium-based inorganic filler and (C) a titanate-based coupling agent, and then blending the mixture with (A) a thermosetting resin.
[6] The resin composition according to any one of the above [1] to [5], further comprising (D) an inorganic filler having a lower dielectric constant (Dk) than the titanium-based inorganic filler (B).
[7] (D) The resin composition according to the above [6], wherein the inorganic filler having a lower dielectric constant (Dk) than the titanium-based inorganic filler (B) is at least one selected from the group consisting of silica and alumina.
[8] The resin composition according to any one of [1] to [7] above, wherein the (A) thermosetting resin is one or more selected from the group consisting of maleimide compounds having one or more N-substituted maleimide groups and derivatives thereof.
[9] The resin composition according to any one of the above [1] to [8], wherein the dielectric constant (Dk) of the cured product at 20 GHz is 2 to 50.
[10] The resin composition according to any one of [1] to [9] above, which is for an antenna module.
[11] A prepreg containing the resin composition according to any one of [1] to [10] above.
[12] A laminate comprising the prepreg according to [11] above and a metal foil.
[13] A resin film comprising the resin composition according to any one of [1] to [10] above.
[14] A multilayer printed wiring board comprising one or more selected from the group consisting of the prepreg according to [11] above, the laminate according to [12] above, and the resin film according to [13] above.
[15] An antenna device comprising the multilayer printed wiring board according to [14] above.
[16] An antenna module comprising the antenna device according to [15] above and a power supply circuit.

According to this embodiment, it is possible to provide a resin composition containing a titanium-based inorganic filler, which has excellent heat resistance, as well as prepregs, laminates, resin films, multilayer printed wiring boards, antenna devices, and antenna modules 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, the term "resin composition" includes a mixture of the components described below and a semi-cured product of the mixture.

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

The mechanism of action described in this specification is speculation and does not limit the mechanism by which the resin composition according to this embodiment exhibits its effects.
Any combination of the features described in this specification is also included in this embodiment.

[Resin composition]
The resin composition of the present embodiment is
(A) a thermosetting resin;
(B) a titanium-based inorganic filler;
(C) a titanate-based coupling agent;
It is a resin composition comprising:

In the following description, the thermosetting resin (A) may be referred to as "component (A)."
Furthermore, the titanium-based inorganic filler (B) may be referred to as "component (B)."
Furthermore, the titanate coupling agent (C) may be referred to as "component (C)."

The reason why the resin composition of the present embodiment has excellent heat resistance is presumed to be as follows.
The resin composition of this embodiment is obtained by blending (B) a titanium-based inorganic filler with (C) a titanate-based coupling agent.
Because the (C) titanate-based coupling agent contains a titanium atom and an organic group, it has a high affinity with both the (B) titanium-based inorganic filler and the (A) thermosetting resin. Therefore, it is believed that the (C) titanate-based coupling agent bonds strongly to the (B) titanium-based inorganic filler and also to the (A) thermosetting resin. This is thought to effectively reinforce the bonding strength at the organic-inorganic interface in the resin composition, improving heat resistance.
Hereinafter, each component that may be contained in the resin composition of the present embodiment will be described in order.

<(A) Thermosetting resin>
Examples of (A) thermosetting resins include epoxy resins, phenolic resins, maleimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins.
The thermosetting resin (A) may be used alone or in combination of two or more kinds.
Among these, as the (A) thermosetting resin, a maleimide resin is preferred from the viewpoints of heat resistance, low thermal expansion, and being less susceptible to unintended curing-accelerating effects of the (B) titanium-based inorganic filler, as well as excellent moldability for circuit embedding and the like, and one or more types selected from the group consisting of maleimide compounds having one or more N-substituted maleimide groups and derivatives thereof are more preferred.
In the following description, "one or more compounds selected from the group consisting of maleimide compounds having one or more N-substituted maleimide groups and derivatives thereof" may be referred to as "maleimide resin."
In the following description, a maleimide compound having one or more N-substituted maleimide groups may be referred to as a "maleimide compound (AX)" or a "(AX) component."
Furthermore, a derivative of a maleimide compound having one or more N-substituted maleimide groups may be referred to as a "maleimide compound derivative (AY)" or a "(AY) component."

(Maleimide Compound (AX))
The maleimide compound (AX) is not particularly limited as long as it is a maleimide compound having one or more N-substituted maleimide groups.
As the maleimide compound (AX), from the viewpoints of dielectric properties, conductor adhesion, and heat resistance, a maleimide compound (A1) having two or more N-substituted maleimide groups [hereinafter, may be referred to as "maleimide compound (A1)" or "component (A1)"] is preferred, an aromatic maleimide compound having two or more N-substituted maleimide groups is more preferred, and an aromatic bismaleimide compound having two N-substituted maleimide groups is even more preferred.
In this specification, the term "aromatic maleimide compound" refers to a compound having an N-substituted maleimide group directly bonded to an aromatic ring, and the term "aromatic bismaleimide compound" refers to a compound having two N-substituted maleimide groups directly bonded to an aromatic ring.

[Maleimide compound (A1)]
The maleimide compound (A1) is preferably a maleimide compound represented by the following general formula (A1-1).

(In the formula, X ^a11 is a divalent organic group.)

In the above general formula (A1-1), X ^a11 is a divalent organic group.
Examples of the divalent organic group represented by X ^a11 in general formula (A1-1) above include a divalent group represented by general formula (A1-2) below, a divalent group represented by general formula (A1-3) below, a divalent group represented by general formula (A1-4) below, a divalent group represented by general formula (A1-5) below, and a divalent group represented by general formula (A1-6) below.

(In the formula, R ^a11 is an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; n ^a11 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 ^a11 in general formula (A1-2) 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 (A1-2), n ^a11 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 ^a11 is an integer of 2 or more, the multiple R ^a11 's may be the same or different.

(In the formula, R ^a12 and R ^a13 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a12 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 group represented by the following general formula (A1-3-1). n ^a12 and n ^a13 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 ^a12 and R ^a13 in general formula (A1-3) 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 ^a12 in general formula (A1-3) 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 ^a12 in general formula (A1-3) 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 above general formula (A1-3), n ^a12 and n ^a13 each independently represent an integer of 0 to 4.
When n ^a12 or n ^a13 is an integer of 2 or more, a plurality of R ^a12s or a plurality of R ^a13s may be the same or different.

The divalent group represented by X ^a12 in the general formula (A1-3) and represented by the general formula (A1-3-1) is as follows.

(In the formula, R ^a14 and R ^a15 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a13 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 ^a14 and n ^a15 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 ^a14 and R ^a15 in general formula (A1-3-1) 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 ^a13 in general formula (A1-3-1) 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 ^a13 in general formula (A1-3-1) 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.

Among the above options, X ^a13 in general formula (A1-3-1) is preferably an alkylidene group having 2 to 5 carbon atoms, more preferably an alkylidene group having 2 to 4 carbon atoms, and even more preferably an isopropylidene group.

In the general formula (A1-3-1) above, n ^a14 and n ^a15 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 ^a14 or n ^a15 is an integer of 2 or greater, a plurality of R ^a14s or a plurality of R ^a15s may be the same or different.

As X ^a12 in the above general formula (A1-3), 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 group represented by the above general formula (A1-3-1) 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 ^a16 is an integer of 0 to 10. * represents a binding site.)

In the above general formula (A1-4), n ^a16 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, from the viewpoint of availability.

(In the formula, n ^a17 is a number from 0 to 5. * represents a binding site.)

(In the formula, R ^a16 and R ^a17 each independently represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms. n ^a18 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 ^a16 and R ^a17 in general formula (A1-6) 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 groups; 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 linear or branched.
In the general formula (A1-6) above, n ^a18 represents 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 ^a18 is an integer of 2 or greater, multiple R ^a16s or multiple R ^a17s may be the same or different.

Examples of the maleimide compound (A1) include aromatic bismaleimide compounds, aromatic polymaleimide compounds, and aliphatic maleimide compounds.
Specific examples of the maleimide compound (A1) 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, 3,3'-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)cyclohexane, 1,3-bis(4-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 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]ketone bis[4-(4-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)phenyl]ether, 1,4-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, Examples of suitable phenylene compounds include 1,3-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-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, and polyphenylmethane maleimide. Among these, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane is preferred.

(Maleimide compound derivative (AY))
The maleimide compound derivative (AY) is preferably an aminomaleimide compound having a structural unit derived from the above-mentioned maleimide compound (AX) and a structural unit derived from a diamine compound [hereinafter, sometimes referred to as "aminomaleimide compound (A2)" or "component (A2)"].

[Aminomaleimide compound (A2)]
The aminomaleimide compound (A2) has a structural unit derived from the maleimide compound (AX) and a structural unit derived from a diamine compound (hereinafter, may be referred to as "diamine compound (a)" or "component (a)").

<Structural unit derived from maleimide compound (AX)>
Examples of the structural unit derived from the maleimide compound (AX) 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 compound (AX) and an amino group contained in a diamine compound.
The structural unit derived from the maleimide compound (AX) contained in the aminomaleimide compound (A2) may be of one type alone or may be of two or more types.

The content of structural units derived from maleimide compound (AX) in aminomaleimide compound (A2) is not particularly limited, but is preferably 5 to 95% by mass, more preferably 30 to 93% by mass, and even more preferably 60 to 90% by mass. When the content of structural units derived from maleimide compound (AX) in aminomaleimide compound (A2) is within the above range, the dielectric properties and film handling properties tend to be better.

<<Structural Unit Derived from Diamine Compound (a)>>
Examples of the structural unit derived from the diamine compound (a) include a structural unit formed by a Michael addition reaction of one or both of the two amino groups contained in the diamine compound (a) with an N-substituted maleimide group contained in the maleimide compound (AX).
The structural unit derived from the diamine compound (a) contained in the aminomaleimide compound (A2) may be of one type alone or may be of two or more types.

The amino group contained in the diamine compound (a) is preferably a primary amino group.
Examples of the structural unit derived from the diamine compound (a) having two primary amino groups include a group represented by the following general formula (a-1) and a group represented by the following general formula (a-2).

(In the formula, X ^a21 represents a divalent organic group, and * represents a bonding site.)

X ^a21 in the general formula (a-1) and the general formula (a-2) above is a divalent organic group, and corresponds to the divalent group obtained by removing two primary amino groups from the diamine compound (a).

X ^a21 in the above general formula (a-1) and the above general formula (a-2) is preferably a divalent group represented by the following general formula (a-3).

(In the formula, R ^a21 and R ^a22 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, or a halogen atom. X ^a22 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 fluorenylene group, a single bond, or a divalent group represented by the following general formula (a-3-1) or the following general formula (a-3-2). n ^a21 and n ^a22 each independently represent an integer of 0 to 4. * represents a bonding site.)

(In the formula, R ^a23 and R ^a24 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a23 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an m-phenylenediisopropylidene group, a p-phenylenediisopropylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. n ^a23 and n ^a24 each independently represent an integer of 0 to 4. * represents a bonding site.)

(In the formula, R ^a25 represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. X ^a24 and X ^a25 each independently represent 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 ^a25 represents 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 ^a21 , R ^a22 , R a23 , R ^a24 and R ^a25 in the general formula (a-3), the general formula (a-3-1) and the general formula (a-3-2) 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. The aliphatic hydrocarbon group having 1 to 5 carbon atoms is preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or an ethyl group.
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 ^a22 in general formula (a-3), X ^a23 in general formula (a-3-1), and X ^a24 and X ^a25 in general formula (a-3-2) 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 ^a22 in general formula (a-3), X ^a23 in general formula (a-3-1), and X ^a24 and X ^a25 in general formula (a-3-2) include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. The alkylidene group having 2 to 5 carbon atoms is preferably an alkylidene group having 2 to 4 carbon atoms, more preferably an alkylidene group having 2 or 3 carbon atoms, and even more preferably an isopropylidene group.

In the general formula (a-3), n ^a21 and n ^a22 each independently represent an integer of 0 to 4, and from the viewpoint of availability, each is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and even more preferably 0 or 2.
When n ^a21 or n ^a22 is an integer of 2 or greater, a plurality of R ^a21 's or a plurality of R ^a22 's may be the same or different.

In the general formula (a-3-1), n ^a23 and n ^a24 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 ^a23 or n ^a24 is an integer of 2 or greater, a plurality of R ^a23s or a plurality of R ^a24s may be the same or different.

In the above general formula (a-3-2), n ^a25 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 ^a25 is an integer of 2 or more, the multiple R ^a25s may be the same or different from each other.

The content of structural units derived from diamine compound (a) in aminomaleimide compound (A2) is not particularly limited, but is preferably 5 to 95% by mass, more preferably 7 to 70% by mass, and even more preferably 10 to 40% by mass. When the content of structural units derived from diamine compound (a) in aminomaleimide compound (A2) is within the above range, the dielectric properties, heat resistance, flame retardancy, and glass transition temperature tend to be better.

Examples of diamine compound (a) 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, Examples include 3-phenylenebis(1-methylethylidene)]bisaniline, 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.

Among these, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, and 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline are preferred as diamine compound (a) from the viewpoints of excellent solubility in organic solvents, reactivity, and heat resistance.

In the aminomaleimide compound (A2), the equivalent ratio (Ta2/Ta1) between the total equivalent ( _Ta2 ) of groups (including _—NH2 ) derived from the —NH2 group of the diamine compound (a) and the total equivalent (Ta1) of groups derived from the N-substituted maleimide group of the maleimide compound (AX) is not particularly limited, but from the viewpoints of dielectric properties, heat resistance, flame retardancy, and glass transition temperature, it is preferably 0.05 to 10, more preferably 0.5 to 7, and even more preferably 1 to 5. The _—NH2 group derived from the diamine compound (a) also includes _—NH2 itself. Furthermore, the N-substituted maleimide group derived from the maleimide compound (AX) also includes the N-substituted maleimide group itself.

The weight-average molecular weight (Mw) of the aminomaleimide compound (A2) is not particularly limited, but is preferably 400 to 10,000, more preferably 500 to 6,000, and even more preferably 1,000 to 6,000. The weight-average molecular weight (Mw) of the aminomaleimide compound (A2) can be measured by the method described in the Examples.

(Method for producing aminomaleimide compound (A2))
The aminomaleimide compound (A2) can be produced, for example, by reacting the maleimide compound (AX) with the diamine compound (a) in an organic solvent.
By reacting the maleimide compound (AX) with the diamine compound (a), an aminomaleimide compound (A2) is obtained through a Michael addition reaction between the maleimide compound (AX) and the diamine compound (a).

When the maleimide compound (AX) is reacted with the diamine compound (a), a reaction catalyst may be used as needed.
Examples of the reaction catalyst include acidic catalysts such as p-toluenesulfonic acid, amines such as triethylamine, pyridine, and tributylamine, imidazoles such as methylimidazole and phenylimidazole, and phosphorus-based catalysts such as triphenylphosphine. These may be used alone or in combination of two or more.
The amount of the reaction catalyst to be added is not particularly limited, but from the viewpoint of the reaction rate and reaction uniformity, it is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total amount of the maleimide compound (AX) and the diamine compound (a).

The reaction temperature for the Michael addition reaction is preferably 50 to 160°C, more preferably 60 to 150°C, and even more preferably 70 to 140°C, from the viewpoints of workability such as reaction rate, suppression of gelation of the product during the reaction, and the like.
The reaction time for the Michael addition reaction is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, and even more preferably 2 to 6 hours, from the viewpoints of productivity and allowing the reaction to proceed sufficiently.
However, these reaction conditions can be appropriately adjusted depending on the types of raw materials used, and are not particularly limited.

In the Michael addition reaction, the solids concentration and solution viscosity of the reaction solution may be adjusted by adding or concentrating an organic solvent. The solids concentration of the reaction solution is not particularly limited, but is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, and even more preferably 20 to 80% by mass. When the solids concentration of the reaction raw materials is equal to or greater than the above-mentioned lower limit, a good reaction rate is obtained and productivity tends to be improved. Furthermore, when the solids concentration of the reaction raw materials is equal to or less than the above-mentioned upper limit, better solubility is obtained, stirring efficiency is improved, and gelation of the product during the reaction tends to be more effectively suppressed.

In the resin composition of the present embodiment, the blending amount of the (A) thermosetting resin is not particularly limited, but is preferably 5 to 100 mass %, more preferably 10 to 99.8 mass %, and even more preferably 20 to 99.5 mass %, relative to the total (100 mass %) of the resin components in the resin composition of the present embodiment.
When the blending amount of (A) thermosetting resin is equal to or greater than the above lower limit, the heat resistance, moldability, processability, and conductor adhesion tend to be better. On the other hand, when the blending amount of (A) thermosetting resin is equal to or less than the above upper limit, the dielectric properties tend to be better.

The content of the maleimide resin in the thermosetting resin (A) is not particularly limited, but is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, relative to the thermosetting resin (A) (100 mass%).
When the content of the maleimide resin is equal to or greater than the lower limit, the heat resistance, moldability, processability, and conductor adhesion tend to be better, whereas when the content of the maleimide resin is equal to or less than the upper limit, the dielectric properties tend to be better.

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 this embodiment, the thermosetting resin (A) corresponds to the resin component.
When the resin composition of the present embodiment contains, as an optional component, a resin or a compound that forms a resin by a curing reaction other than the above components, these optional components are also included in the resin component, and the curing accelerator described below is included in the resin component.
On the other hand, the inorganic filler, (C) the titanate coupling agent, and the flame retardant are not included in the resin component.

In the resin composition of the present embodiment, the blending amount of the resin component is not particularly limited, but is preferably 5 to 80 mass %, more preferably 10 to 70 mass %, and even more preferably 15 to 50 mass %, based on the total solid content of the resin composition.
When the blending amount of the resin component is equal to or greater than the lower limit, the heat resistance, moldability, processability, and conductor adhesion tend to be better, whereas when the blending amount of the resin component is equal to or less than the upper limit, the dielectric properties tend to be better.

<(B) Titanium-based inorganic filler>
The resin composition of the present embodiment contains (B) a titanium-based inorganic filler.
The titanium-based inorganic filler (B) may be used alone or in combination of two or more.

Examples of the titanium-based inorganic filler (B) include titanium dioxide, titanates, etc. Among these, titanates are preferred from the viewpoint of easily increasing the relative dielectric constant (Dk) of the cured product of the resin composition.
Examples of titanates include alkali metal titanates, alkaline earth metal titanates, etc. Among these, from the viewpoint of easily increasing the dielectric constant (Dk) of a cured product of the resin composition, one or more selected from the group consisting of barium titanate, potassium titanate, calcium titanate, strontium titanate, lead titanate, and aluminum titanate are preferred, and calcium titanate and strontium titanate are more preferred.

The average particle size (D ₅₀ ) of the titanium-based inorganic filler (B) is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and even more preferably 0.7 to 10 μm.
When the average particle diameter ( _D50 ) of the (B) titanium-containing inorganic filler is equal to or greater than the lower limit, the specific surface area of the (B) titanium-containing inorganic filler becomes small, and the promotion of unintended curing reaction of the (A) thermosetting resin by the solid surface of the (B) titanium-containing inorganic filler tends to be easily suppressed. Also, when the average particle diameter ( _D50 ) of the (B) titanium-containing inorganic filler is equal to or less than the upper limit, the homogeneity of the cured product of the resin composition tends to be more easily improved.
The average particle size (D ₅₀ ) of the titanium-based inorganic filler (B) can be measured by the method described in the examples.

The relative dielectric constant (Dk) of the titanium-based inorganic filler (B) at 10 GHz is not particularly limited, but is preferably 10 to 3,000, more preferably 13 to 2,500, and even more preferably 15 to 2,000.
When the (B) titanium-based inorganic filler has a dielectric constant (Dk) at 10 GHz of at least the lower limit, the dielectric constant (Dk) of the cured product of the resin composition tends to be higher. When the (B) titanium-based inorganic filler has a dielectric constant (Dk) at 10 GHz of at most the upper limit, the titanium-based inorganic filler tends to be more easily available and to maintain a good balance with other physical properties.
The relative dielectric constant (Dk) at 10 GHz of (B) the titanium-based inorganic filler can be measured by the method described in the Examples.

The blending amount of the titanium-based inorganic filler (B) in the resin composition of the present embodiment is not particularly limited, but is preferably 15 to 80 mass %, more preferably 25 to 75 mass %, and even more preferably 30 to 70 mass %, based on the total amount of solids in the resin composition.
When the blending amount of (B) titanium-based inorganic filler is equal to or greater than the above lower limit, the dielectric constant (Dk) of the cured product of the resin composition tends to be increased, whereas when the blending amount of (B) titanium-based inorganic filler is equal to or less than the above upper limit, the moldability tends to be improved.

<(C) Titanate-Based Coupling Agent>
The resin composition of the present embodiment is prepared by blending (C) a titanate-based coupling agent.
The titanate coupling agents (C) may be used singly or in combination of two or more.

The titanate coupling agent (C) is preferably one having a titanium atom and an organic group bonded to the titanium atom.
In this specification, the term "organic group" refers to a group formed by removing one hydrogen atom from an organic compound.
The organic group bonded to the titanium atom preferably has 1 to 25 carbon atoms, more preferably 2 to 22 carbon atoms, and even more preferably 3 to 20 carbon atoms.
The number of organic groups bonded to the titanium atom is preferably 1 to 4, more preferably 2 to 4, and even more preferably 3 or 4.

(C) The titanate-based coupling agent is preferably a compound represented by the following general formula (C-1):

(In the formula, each R ^c1 is independently an organic group having 1 to 25 carbon atoms.)

The organic group having 1 to 25 carbon atoms represented by R ^c1 preferably has 1 to 25 carbon atoms, more preferably 2 to 22 carbon atoms, and even more preferably 3 to 20 carbon atoms.

Examples of the organic group having 1 to 25 carbon atoms represented by R ^c1 include groups represented by any of the following general formulae (C-2) to (C-5).

(In the formula, R ^c2 to R ^c5 each independently represent an aliphatic hydrocarbon group having 1 to 25 carbon atoms. In the general formula (C-5) above, n ^c1 represents an integer of 1 to 5.)

In the above general formulas (C-2) to (C-5), examples of the aliphatic hydrocarbon group having 1 to 25 carbon atoms represented by R ^c2 to R ^c5 include an alkyl group having 1 to 25 carbon atoms, an alkenyl group having 2 to 25 carbon atoms, and an alkynyl group having 2 to 25 carbon atoms. Of these, an alkyl group having 1 to 25 carbon atoms is preferred.
Examples of alkyl groups having 1 to 25 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, etc. These alkyl groups may be linear or branched.
The alkyl group may or may not have a substituent.
Examples of the substituent that the alkyl group may have include an aromatic hydrocarbon group; an aromatic heterocyclic group; a halogen atom; an alkoxy group, an aryloxy group, a hydroxy group, a carboxy group, an amino group; and groups formed by combining these. The amino group as a substituent may be an alkyl-substituted amino group, and examples of the alkyl-substituted amino group include N-aminoethyl-aminoethyl. The number of carbon atoms in the substituent is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 4.

Among the above options, R ^c1 in the general formula (C-1) is preferably a group represented by the general formula (C-2) above, and R ^c2 is more preferably a group represented by the general formula (C-2) above, which is an alkyl group having 1 to 25 carbon atoms.

n ^c1 is an integer of 1 to 5, preferably an integer of 2 to 4, more preferably 3 or 4, and even more preferably 4.

(C) Titanate coupling agents include, for example, tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraisobutyl titanate, tetrahexyl titanate, tetra(2-ethylhexyl) titanate, tetraoctyl titanate, and butyl titanate dimer. Other preferred examples of the titanate coupling agent include tetraisopropyl titanate, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, and tetraoctyl bis(ditridecyl phosphite). bis(dioctyl phosphate) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, dicumyl phenyloxyacetate titanate, diisostearoyl ethylene titanate, etc.

The amount of the titanate coupling agent (C) in the resin composition of the present embodiment is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 6 parts by mass, per 100 parts by mass of the titanium-based inorganic filler (B).
When the blending amount of (C) titanate-based coupling agent is equal to or greater than the above lower limit, the heat resistance of the resin composition tends to be more easily improved, and when the blending amount of (C) titanate-based coupling agent is equal to or less than the above upper limit, the economic efficiency tends to be more easily improved.

The method of blending the titanate coupling agent (C) may be a so-called integral blending method in which the surface-untreated titanium inorganic filler (B) is blended with other components to form a composition, and then the titanate coupling agent (C) is added to the composition. However, from the viewpoint of making it easier to obtain better heat resistance, the resin composition of this embodiment is preferably one in which the titanium inorganic filler (B) and the titanate coupling agent (C) are mixed together and then blended with the thermosetting resin (A).
Examples of the method for treating the surface of the titanium-based inorganic filler (B) with the titanate-based coupling agent (C) include a dry surface treatment method and a wet surface treatment method.
The dry surface treatment method may include, for example, a method in which (C) a titanate-based coupling agent or (C) a titanate-based coupling agent diluted with a solvent is mixed with (B) a titanium-based inorganic filler, and then dried as necessary. The mixing may be carried out using, for example, a mixer.
An example of the wet surface treatment method is a method in which (B) the titanium-based inorganic filler and (C) the titanate-based coupling agent are mixed in a solvent to form a slurry, followed by filtering and drying.

<(D) Low Dielectric Inorganic Filler>
From the viewpoint of reducing the thermal expansion of the cured resin composition, the resin composition of the present embodiment preferably further contains (D) an inorganic filler having a lower dielectric constant (Dk) than the titanium-based inorganic filler (B) (hereinafter also referred to as "(D) low dielectric inorganic filler").
Since the (D) low-dielectric inorganic filler is an inorganic compound, its addition contributes to reducing the thermal expansion coefficient of the resin composition. Furthermore, since the (D) low-dielectric inorganic filler has a lower dielectric constant (Dk) than the (B) titanium-based inorganic filler, its addition can minimize changes in the dielectric constant (Dk) of the entire resin composition. As a result, a resin composition containing the (D) low-dielectric inorganic filler can effectively reduce the thermal expansion coefficient of the cured product without significantly varying the dielectric constant (Dk) of the resin composition from the designed value.
The low dielectric inorganic filler (D) may be used alone or in combination of two or more.

(D) The low-dielectric inorganic filler is not particularly limited as long as it is an inorganic filler with a lower dielectric constant (Dk) than the (B) titanium-based inorganic filler, but examples include silica, alumina, mica, beryllia, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, aluminum borate, and silicon carbide. Among these, from the viewpoint of low thermal expansion, one or more selected from the group consisting of silica, alumina, mica, and talc are preferred, one or more selected from the group consisting of silica and alumina are more preferred, and silica is even more preferred.

The average particle size (D ₅₀ ) of the low dielectric inorganic filler (D) is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.3 to 12 μm.
When the average particle diameter ( _D50 ) of the (D) low dielectric inorganic filler is equal to or greater than the above lower limit, the dispersibility of the (D) low dielectric inorganic filler tends to be improved. On the other hand, when the average particle diameter ( _D50 ) of the (D) low dielectric inorganic filler is equal to or less than the above upper limit, the sedimentation of the (D) low dielectric inorganic filler tends to be more easily suppressed.
The average particle size (D ₅₀ ) of the low dielectric inorganic filler (D) can be measured by the method described in the examples.

The dielectric constant (Dk) at 10 GHz of the (D) low dielectric inorganic filler is not particularly limited, but it is preferable that the dielectric constant (Dk) is at least one order of magnitude lower than that of the (B) titanium-based inorganic filler. For example, the dielectric constant (Dk) at 10 GHz of the (D) low dielectric inorganic filler may be in the range of 1/1000 to 1/5, 1/500 to 1/10, or 1/100 to 1/20 of the dielectric constant (Dk) at 10 GHz of the (B) titanium-based inorganic filler.
When the dielectric constant (Dk) at 10 GHz of the (D) low dielectric inorganic filler is within the above range, the fluctuation in the dielectric constant (Dk) of the cured product of the resin composition due to the addition of the (D) low dielectric inorganic filler tends to be smaller.
The relative dielectric constant (Dk) at 10 GHz of the (D) low dielectric inorganic filler can be measured by the method described in the Examples.

The amount of the low dielectric inorganic filler (D) in the resin composition of the present embodiment is not particularly limited, but is preferably 10 to 60 mass %, more preferably 20 to 50 mass %, and even more preferably 25 to 40 mass %, relative to the total amount of solids in the resin composition.
When the blending amount of the (D) low dielectric inorganic filler is equal to or greater than the above lower limit, the coefficient of thermal expansion of the cured product of the resin composition tends to be smaller. On the other hand, when the blending amount of the (D) low dielectric inorganic filler is equal to or less than the above upper limit, the fluctuation in the relative dielectric constant (Dk) of the cured product of the resin composition due to the addition of the (D) low dielectric inorganic filler tends to be smaller.

The total amount of the (B) titanium-based inorganic filler and the (D) low dielectric inorganic filler in the resin composition of this embodiment is preferably 20 to 95 mass %, more preferably 50 to 90 mass %, and even more preferably 70 to 85 mass %, based on the total amount of solids in the resin composition.
When the total amount of the (B) titanium-based inorganic filler and the (D) low-dielectric inorganic filler is equal to or greater than the lower limit, a higher dielectric constant (Dk) and a lower coefficient of thermal expansion tend to be easily obtained. When the total amount of the (B) titanium-based inorganic filler and the (D) low-dielectric inorganic filler is equal to or less than the upper limit, the moldability tends to be more easily improved.

The proportion of the combined amount of (B) titanium-based inorganic filler and (D) low-dielectric inorganic filler relative to the total amount of inorganic fillers contained in the resin composition of this embodiment is not particularly limited, but is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

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

(E) Examples of curing accelerators include acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, tributylamine, and dicyandiamide; imidazole compounds such as methylimidazole, phenylimidazole, and 1-cyanoethyl-2-phenylimidazole; isocyanate-masked imidazole compounds such as the addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; 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 curing acceleration effect and storage stability, amine compounds and imidazole compounds are preferred, and dicyandiamide and 1-cyanoethyl-2-phenylimidazole are more preferred.

When the curing accelerator (E) is blended into the resin composition of the present embodiment, the blending amount thereof 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, relative to 100 parts by mass of the thermosetting resin (A).
When the blending amount of the (E) curing accelerator is equal to or greater than the above lower limit, a sufficient curing acceleration effect tends to be easily obtained, and when the blending amount of the (E) curing accelerator is equal to or less than the above upper limit, storage stability tends to be better.

<Other ingredients>
The resin composition of the present embodiment may or may not contain other components in addition to the above components, as necessary.
Examples of other components include (A) resins other than thermosetting resins, flame retardants, organic solvents, and other additives.
These may be used singly or in combination of two or more.

(A) Examples of resins other than thermosetting resins include thermoplastic resins.
Examples of thermoplastic resins include polyphenylene ether resins; thermoplastic elastomers such as styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, silicone-based thermoplastic elastomers, and derivatives thereof.

Examples of the flame retardant include phosphorus-based flame retardants, metal hydrates, halogen-based flame retardants, etc. Among these, from the viewpoint of environmental issues, phosphorus-based flame retardants and metal hydrates are preferred.
The phosphorus-based flame retardant may be an inorganic phosphorus-based flame retardant, but from the viewpoints of dielectric properties, adhesion to conductors, heat resistance, glass transition temperature, low thermal expansion, and flame retardancy, an organic phosphorus-based flame retardant is preferred.
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 esters, mono-substituted phosphonic acid diesters, di-substituted phosphinic acid esters, metal salts of di-substituted phosphinic acids, organic nitrogen-containing phosphorus compounds, cyclic organic phosphorus compounds, phosphine oxide compounds, etc. Here, examples of metal salts of di-substituted phosphinic acids include lithium salts, sodium salts, potassium salts, calcium salts, magnesium salts, aluminum salts, titanium salts, zinc salts, etc.

Examples of organic solvents include acetone, methyl ethyl ketone, toluene, xylene, cyclohexanone, 4-methyl-2-pentanone, ethyl acetate, ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, N,N-dimethylformamide, and N,N-dimethylacetamide.

Other additives include, for example, ultraviolet absorbers such as benzotriazoles; antioxidants such as hindered phenol antioxidants and styrenated phenol antioxidants; photopolymerization initiators such as benzophenones, benzil ketals, and thioxanthones; fluorescent brighteners such as stilbene derivatives, adhesion improvers such as urea compounds and silane coupling agents; and crosslinkers such as cyanamide crosslinkers.

The content of other ingredients is not particularly limited, and they may be used as needed within a range that does not impair the effects of this embodiment.

<Method of producing resin composition>
The resin composition of the present embodiment can be produced by mixing the above components.
When mixing the components, the components may be dissolved or dispersed while being stirred. The mixing order of the raw materials, the mixing temperature, the mixing time, and other conditions are not particularly limited and may be set arbitrarily depending on the types of raw materials, etc.

<Relative dielectric constant (Dk) of cured product>
The relative dielectric constant (Dk) at 20 GHz of the cured product of the resin composition of this embodiment is not particularly limited, but is preferably 2 to 50, more preferably 3 to 40, and even more preferably 5 to 35.
When the dielectric constant (Dk) at 20 GHz of the cured product is equal to or greater than the lower limit, the antenna module tends to be more easily miniaturized. On the other hand, when the dielectric constant (Dk) at 20 GHz of the cured product is equal to or less than the upper limit, the antenna module tends to be more easily balanced with other physical properties.
The relative dielectric constant (Dk) at 20 GHz of the cured product of the resin composition of this embodiment can be measured by the method described in the examples.

<Thermal expansion coefficient of the cured product>
The coefficient of thermal expansion of the cured product of the resin composition of the present embodiment is not particularly limited, but from the viewpoint of making it easier to suppress the occurrence of warping, it is preferably 35 ppm/°C or less, more preferably 30 ppm/°C or less, and even more preferably 25 ppm/°C or less.
There is no particular restriction on the lower limit of the coefficient of thermal expansion of the cured product of the resin composition of the present embodiment, but from the viewpoint of maintaining a good balance with other physical properties, it may be 5 ppm/°C or more, 10 ppm/°C or more, or 15 ppm/°C or more.
The coefficient of thermal expansion of the cured product of the resin composition of this embodiment can be measured by the method described in the examples.

<Uses of resin composition>
The resin composition of this embodiment is a resin composition containing a titanium-based inorganic filler and has excellent heat resistance, and is therefore suitable as a resin composition for an antenna module.

[Prepreg]
The prepreg of this embodiment is a prepreg containing the resin composition of this embodiment.
The prepreg of this embodiment is suitable as a prepreg for an antenna module.
The prepreg of this embodiment is preferably obtained by impregnating or coating a sheet-like fiber substrate with the resin composition of this embodiment and then B-staging the resulting material. In this specification, B-staging refers to achieving the B-stage state defined in JIS K 6900:1994, and is also referred to as semi-curing.

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 thickness of the sheet-like fiber substrate is not particularly limited, but from the viewpoint of mechanical strength and thinning of the prepreg, it is preferably 0.01 to 0.5 mm, more preferably 0.02 to 0.3 mm, and even more preferably 0.03 to 0.1 mm.
The sheet-like fiber substrate may be surface-treated with a coupling agent or the like, or may be mechanically opened, from the viewpoints of impregnation with the resin composition, heat resistance, moisture absorption resistance, and processability when made into a laminate.

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 drying it as necessary.
As a method for impregnating or applying the resin composition of this embodiment to a sheet-like fiber substrate, for example, a hot melt method, a solvent method, or the like can be used.

The hot melt method is a method in which a resin composition containing no organic solvent is impregnated into or coated on a sheet-like fiber substrate.
One aspect of the hot melt method is to first coat the resin composition of this embodiment, which does not contain an organic solvent, onto coated paper with good peelability, and then laminate the coated resin composition onto a sheet-like fiber substrate.
Another embodiment of the hot melt method is a method in which the resin composition of the present embodiment, which does not contain an organic solvent, is directly applied to a sheet-like fiber substrate using a die coater or the like.

The solvent method is a method of impregnating or coating a sheet-like fiber substrate with a resin composition containing an organic solvent. Specifically, for example, a method of immersing a sheet-like fiber substrate in the resin composition of the present embodiment containing an organic solvent and then drying it can be mentioned. By drying, the organic solvent in the resin composition can be removed and the resin composition can be brought into a B-stage.
The drying temperature is not particularly limited, but from the viewpoint of productivity and appropriately B-staging the resin composition of the present embodiment, it is preferably 50 to 200°C, more preferably 100 to 190°C, and even more preferably 150 to 180°C.
The drying time is not particularly limited, but from the viewpoints of productivity and appropriately bringing the resin composition of the present embodiment into a B-stage, it is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and even more preferably 3 to 10 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.

The thickness of the prepreg of this embodiment is not particularly limited, but from the viewpoint of formability and enabling high-density wiring, it is preferably 0.01 to 0.5 mm, more preferably 0.02 to 0.3 mm, and even more preferably 0.03 to 0.1 mm.

[Resin film]
The resin film of the present embodiment is a resin film containing the resin composition of the present embodiment.
The resin film of this embodiment is suitable as a resin film for an antenna module.
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 a release paper.
Examples of plastic films include polyolefin films such as polyethylene, polypropylene, and polyvinyl chloride; polyester films such as polyethylene terephthalate (hereinafter sometimes referred to as "PET") and polyethylene naphthalate; polycarbonate films; and polyimide films. Among these, polyethylene terephthalate films are preferred from the viewpoints of economy and ease of handling.
Examples of metal foils include copper foil and aluminum foil. When copper foil is used as the support, the copper foil itself can be used as a conductor layer to form a circuit. In this case, rolled copper foil, electrolytic copper foil, etc. can be used as the copper foil. When a thin copper foil is used, a copper foil with a carrier may be used from the viewpoint of improving workability.
The support may be subjected to a surface treatment such as matte treatment or corona treatment, or may be subjected to a release treatment using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, or the like.
The thickness of the support is not particularly limited, but from the viewpoints of ease of handling and economy, it is preferably 10 to 150 μm, more preferably 20 to 100 μm, and even more preferably 25 to 50 μm.

The coating device for applying the resin varnish may be any coating device known to those skilled in the art, such as a comma coater, bar coater, kiss coater, roll coater, gravure coater, die coater, etc. These coating devices may be appropriately selected depending on the film thickness to be formed.
The drying conditions after applying the resin varnish may be appropriately determined depending on the content, boiling point, etc. of the organic solvent, and are not particularly limited.
For example, in the case of a resin varnish containing 40 to 60 mass% of an aromatic hydrocarbon solvent, the drying temperature is not particularly limited, but from the viewpoints of productivity and appropriately B-staging the resin composition of the present embodiment, it is preferably 50 to 200°C, more preferably 100 to 190°C, and even more preferably 150 to 180°C.
Furthermore, in the case of the above-mentioned resin varnish, the drying time is not particularly limited, but from the viewpoints of productivity and appropriately bringing the resin composition of the present embodiment into a B-stage, it is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and even more preferably 3 to 10 minutes.

The thickness of the resin film in this embodiment can be determined appropriately depending on the application of the resin film, but from the viewpoint of formability and enabling high-density wiring, it is preferably 5 to 150 μm, more preferably 10 to 100 μm, and even more preferably 15 to 60 μm.

The resin film of this embodiment may have a protective film. The protective film is provided on the surface of the resin film of this embodiment opposite the surface on which the support is provided, and is used for the purpose of preventing the adhesion of foreign matter and scratches to the resin film. The protective film is peeled off before the resin film of this embodiment is laminated, heat pressed, or otherwise stacked on a circuit board or the like.

The resin film of this embodiment is preferably used to form an insulating layer when producing a multilayer printed wiring board.
For example, when a multilayer printed wiring board is produced, the resin film of this embodiment is a layer that melts and flows when laminated onto a circuit board, thereby serving to embed the circuit board.
Furthermore, when a circuit board has through holes, via holes, etc., the resin film of this embodiment flows into the holes and fills them.

[Laminate]
The laminate of this embodiment is a laminate containing the prepreg of this embodiment and a metal foil. Note that a laminate having a metal foil is sometimes called a metal-clad laminate.
The laminate of this embodiment is suitable as a laminate for an antenna module.

The metal of the metal foil is not particularly limited, and examples thereof include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing one or more of these metal elements. Examples of alloys include copper-based alloys, aluminum-based alloys, and iron-based alloys. Examples of copper-based alloys include copper-nickel alloys. Examples of iron-based alloys include iron-nickel alloys.
Among these, from the viewpoints of conductivity and availability, copper, nickel, aluminum, and iron-nickel alloys are preferred, copper and aluminum are more preferred, and copper is even more preferred.
The thickness of the metal foil is not particularly limited, but is preferably 1 to 200 μm, more preferably 2 to 100 μm, and even more preferably 3 to 50 μm.

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 prepreg in a semi-cured state is cured by this heat and pressure molding to obtain the laminate of this embodiment.
In the heat and pressure molding, only one prepreg may be used, or two or more prepregs may be laminated together. In addition to the prepreg and metal foil, the heat and pressure molding may also include a substrate on which an inner layer circuit has been processed.
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 heating temperature for hot pressing is not particularly limited, but is preferably 100 to 300°C, more preferably 150 to 280°C, and even more preferably 200 to 250°C.
The heating and pressing time for the hot and pressure molding is not particularly limited, but is preferably 10 to 300 minutes, more preferably 30 to 200 minutes, and even more preferably 80 to 150 minutes.
The pressure for the hot pressing is not particularly limited, but is preferably 1.5 to 5 MPa, more preferably 1.7 to 3 MPa, and even more preferably 1.8 to 2.5 MPa.
However, these conditions can be adjusted appropriately depending on the type of raw material used, and are not particularly limited.

[Multilayer printed wiring board]
The multilayer printed wiring board of the present embodiment contains one or more materials selected from the group consisting of the prepreg of the present embodiment, the resin film of the present embodiment, and the laminate of the present embodiment.
That is, the multilayer printed wiring board of this embodiment includes at least a multilayer structure containing a cured product of the prepreg of this embodiment, a cured product of the resin film of this embodiment, or a laminate of this embodiment, and a conductor circuit layer.
The multilayer printed wiring board of this embodiment is suitable as a multilayer printed wiring board for an antenna module.
A method for producing a multilayer printed wiring board of this embodiment using the resin film of this embodiment will be described below.

When a multilayer printed wiring board is manufactured using the resin film of this embodiment, the resin film of this embodiment is first laminated onto one or both sides of a circuit board. After the resin film of this embodiment is placed so as to be in contact with the circuit board, the resin film of this embodiment can be laminated onto the circuit board by, for example, pressing the circuit board while applying pressure and heat using a vacuum laminator.
Examples of circuit boards used in multilayer printed wiring boards include glass epoxy, metal, polyester, polyimide, BT resin, and thermosetting polyphenylene ether substrates, each having a patterned conductor layer (circuit) formed on one or both sides thereof.
From the viewpoint of adhesiveness, the surface of the conductor layer of the circuit board may be previously roughened by blackening or the like.

Next, after peeling off the support of the resin film as necessary, the resin film is cured by heating to form an insulating layer.
The heating temperature during heat curing is not particularly limited, but is preferably 100 to 300°C, more preferably 120 to 280°C, and even more preferably 150 to 250°C.
The heating time for heat curing is not particularly limited, but is preferably 2 to 300 minutes, more preferably 5 to 200 minutes, and even more preferably 10 to 150 minutes.

After forming the insulating layer using the above method, drilling may be performed as needed. Drilling is a process in which holes are drilled into the circuit board and the formed insulating layer using methods such as drilling, laser, plasma, or a combination of these to form via holes, through holes, etc. Lasers used for drilling include, for example, carbon dioxide lasers, YAG lasers, UV lasers, and excimer lasers.

Next, the surface of the insulating layer may be roughened with an oxidizing agent. Furthermore, if via holes, through holes, etc. are formed in the insulating layer and the circuit board, the so-called "smear" that occurs when these holes are formed may be removed with an oxidizing agent. The roughening treatment and smear removal can be performed simultaneously. The roughening treatment can form uneven anchors on the surface of the insulating layer.
Examples of the oxidizing agent include permanganates such as potassium permanganate and sodium permanganate, dichromates, ozone, hydrogen peroxide, sulfuric acid, nitric acid, etc. Among these, preferred are aqueous solutions of sodium hydroxide of potassium permanganate and aqueous solutions of sodium hydroxide of sodium permanganate, which are oxidizing agents commonly used in the manufacture of multilayer printed wiring boards by the build-up method.

Next, a conductor layer is formed on the roughened surface of the insulating layer. The conductor layer can be formed by, for example, plating.
Examples of plating methods include electroless plating and electrolytic plating. Examples of metals for plating include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing at least one of these metal elements. Among these, copper and nickel are preferred, and copper is more preferred.
Alternatively, a plating resist having a reverse pattern to the wiring pattern may be formed first, and then the wiring pattern may be formed only by electroless plating.
Furthermore, after the conductor layer is formed, an annealing treatment may be carried out, which tends to further improve and stabilize the adhesive strength between the interlayer insulating layer and the conductor layer.

Methods that can be used to pattern the conductor layer and form circuits include known methods such as the subtractive method, full-additive method, semi-additive method (SAP: Semi-Additive Process), and modified semi-additive method (m-SAP: Modified Semi-Additive Process).

[Antenna device]
The antenna device of this embodiment is an antenna device including the multilayer printed wiring board of this embodiment.
The antenna device of this embodiment can be manufactured by, for example, mounting an antenna element on the multilayer printed wiring board of this embodiment.
There is no particular limitation on the method of installing the antenna elements, but for example, it is preferable to arrange them in a two-dimensional array. There is no particular limitation on the configuration of the antenna device, but for example, reference can be made to Japanese Patent No. 6777273.

[Antenna module]
The antenna module of this embodiment includes the antenna device of this embodiment and a power supply circuit.
The antenna module of this embodiment can be manufactured by a method including, for example, installing a feed circuit and the antenna device of this embodiment.
The power supply circuit is not particularly limited, but may be an RFIC (Radio Frequency Integrated Circuit), etc. The RFIC includes a switch, a power amplifier, a low-noise amplifier, an attenuator, a phase shifter, a signal combiner-demultiplexer, a mixer, an amplifier circuit, etc.
A high frequency signal supplied from the RFIC is transmitted to the feeding point of the feeding conductor via a short-circuiting conductor formed in a via of the antenna module laminate.
The configuration of the antenna module is not particularly limited, but reference can be made to, for example, Japanese Patent No. 6777273.

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

(Method for measuring weight average molecular weight (Mw))
The weight average molecular weight (Mw) 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.
[GPC measurement conditions]
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℃

(Method for measuring the average particle diameter ( _D50 ) of inorganic filler)
The average particle diameter (D ₅₀ ) of the inorganic filler was measured by diluting 0.1 g of the inorganic filler to be measured with 20 g of a solvent (type: methyl ethyl ketone) and then dispersing the diluted material by vibrating it for 5 to 20 minutes with a 100 W ultrasonic homogenizer.
One to two drops of the measurement sample were poured into a measurement cell, and the particle size distribution was measured at 25°C and a refractive index of 1.38 using a particle size distribution measuring device (manufactured by Microtrack Bell Corporation, product name: Microtrack MT3000) in accordance with international standard ISO 13321. The particle size corresponding to an integrated value of 50% (volume basis) in the obtained particle size distribution was defined as the average particle size (D ₅₀ ).

(Method for measuring the relative dielectric constant (Dk) of inorganic filler at 10 GHz)
The relative dielectric constant (Dk) of the inorganic filler at 10 GHz was measured by the following procedure.
The inorganic filler and polyphenylene ether resin to be measured were blended in a ratio of 20% by volume of inorganic filler to 80% by volume of polyphenylene ether resin, and the resulting mixture was press-molded at 230°C for 30 minutes under 3 MPa to obtain a test piece measuring 50 mm wide, 130 mm long, and 0.5 mm thick, for measuring the relative dielectric constant (Dk).
Next, the dielectric constant (Dk) of the test piece obtained above was measured by a cavity resonator perturbation method using the following device and program under the conditions of a frequency of 10 GHz and 25°C.
- Measuring instrument: Agilent Technologies vector network analyzer "N5227A"
Cavity resonator: "CP129" (10 GHz band resonator) manufactured by Kanto Electronics Application Development Co., Ltd.
- Measurement program: "CPMA-V2" manufactured by Kanto Electronics Application Development Co., Ltd.
The dielectric constant (Dk) of the test piece measured above was defined as Dk1, and the dielectric constant (Dk) of the polyphenylene ether resin alone measured in advance under the above measurement conditions was defined as Dk2, and the dielectric constant (Dk) of the inorganic filler alone was calculated based on the following formula.
Relative dielectric constant (Dk) = (Dk1 - Dk2 × 0.2) / 0.8

Production Example 1: Production of Aminomaleimide Compound [0043] 195 parts by mass of 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 34 parts by mass of 3,3'-diethyl-4,4'-diaminodiphenylmethane, and 229 parts by mass of propylene glycol monomethyl ether were charged into a 5-liter reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a water content monitor, and the mixture was allowed to react under reflux for 2 hours. The mixture was concentrated at the reflux temperature for 3 hours to produce an aminomaleimide compound solution with a solids concentration of 65% by mass. The weight-average molecular weight (Mw) of the resulting aminomaleimide compound was approximately 2,200.

[Production of resin composition]
Examples 1 to 5, Comparative Examples 1 to 6
Component (B) and component (C) or a comparative component were blended in the composition shown in Table 1 and mixed in a mixer, whereby component (B) was subjected to a dry surface treatment with component (C).
Next, the mixture and the other components shown in Table 1 were blended in the amounts shown in Table 1, and then stirred and mixed at 25°C to prepare a resin composition. In Table 1, the blend amount of each component is expressed in parts by mass. The aminomaleimide compound was blended as the aminomaleimide compound solution obtained in Production Example 1, and the amounts shown in Table 1 are expressed in parts by mass calculated as solid content.

[Production of resin film and resin plate with double-sided copper foil]
The resin composition obtained above was applied to a 38 μm thick PET film (manufactured by Teijin Limited, product name: G2-38), and then heated and dried for 5 minutes at 170° C. to produce a B-stage resin film. The resin film was peeled off from the PET film and then pulverized to obtain a B-stage resin powder.
The resin powder obtained above was placed into a Teflon (registered trademark) sheet die-cut to a size of 0.5 mm thick x 50 mm long x 35 mm wide, and 18 μm thick low-profile copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product name: 3EC-VLP-18) was placed on top and bottom of it. The low-profile copper foil was placed with the M side facing the resin powder. Next, this pre-heat-pressure-molded laminate was heat-pressurized at a temperature of 230°C, a pressure of 2.0 MPa, and a time of 120 minutes, and the resin powder was molded into a resin plate while being cured, thereby producing a resin plate with double-sided copper foil. The thickness of the resin plate portion of the obtained double-sided copper foil-molded resin plate was 0.5 mm.

[Measurement and evaluation methods]
The resin compositions and resin plates with copper foil on both sides 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.

(1. Measurement of thermal expansion coefficient)
The outer copper foil of the double-sided copper foil-covered resin board obtained above was removed by immersion in a copper etching solution (a 10% by mass solution of ammonium persulfate, manufactured by Mitsubishi Gas Chemical Company, Inc.) to prepare 5 mm square test pieces. The thermal expansion coefficient of the test pieces was then measured using a thermomechanical analyzer (TMA) (manufactured by TA Instruments Japan, product name: Q400) in accordance with the IPC (The Institute for Interconnecting and Packaging Electronic Circuits) standard. The thermal expansion coefficient was the thermal expansion coefficient in the thickness direction of the resin board, and was the average thermal expansion coefficient over a temperature range of 30 to 120°C.

(2. Measurement of relative dielectric constant (Dk))
The outer copper foil of the double-sided copper foil-covered resin board obtained above was removed by immersion in a copper etching solution (a 10% by mass solution of ammonium persulfate, manufactured by Mitsubishi Gas Chemical Company, Inc.), and then cut into a length of 60 mm and a width of 0.5 mm to prepare a test piece for measuring the dielectric constant (Dk). The dielectric constant (Dk) of this test piece was measured by a cavity resonator perturbation method using the following apparatus and program under conditions of a frequency of 20 GHz and 25°C.
- Measuring instrument: Agilent Technologies vector network analyzer "N5227A"
Cavity resonator: "CP129" (10 GHz band resonator) manufactured by Kanto Electronics Application Development Co., Ltd.
- Measurement program: "CPMA-V2" manufactured by Kanto Electronics Application Development Co., Ltd.

(3. Evaluation of solder heat resistance)
The resin board with copper foil on both sides obtained above was cut into 25 mm squares, floated in a solder bath at 288°C, and visually observed to measure the time (unit: seconds) until the board blistered. The maximum observation time was 1200 seconds, and if no blistering was observed after 1200 seconds, it was marked as ">1200." If blistering occurred within 2 seconds, it was marked as "<2."

The details of each component shown in Table 1 are as follows:
[(B) Component]
Calcium titanate: manufactured by Kyoritsu Material Co., Ltd., product name "CT-3", average particle size (D ₅₀ ): 2 μm, relative dielectric constant (Dk) (10 GHz): 175
Strontium titanate: manufactured by Sakai Chemical Industry Co., Ltd., product name "ST-03", average particle size (D ₅₀ ): 0.3 μm, relative dielectric constant (Dk) (10 GHz): 220
[(C) Component]
Titanate coupling agent 1: isopropyl tri(N-aminoethyl-aminoethyl) titanate Titanate coupling agent 2: tetraoctyl titanate [comparison component]
Silane coupling agent: 3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-903"
[(D) Component]
Silica: manufactured by Admatechs Co., Ltd., product name "SC-05", average particle diameter (D ₅₀ ): 1.5 μm, relative dielectric constant (Dk) (10 GHz): 4

Table 1 shows that the resin compositions of Examples 1 to 5 of this embodiment have excellent solder heat resistance, dielectric constant, and thermal expansion coefficient. On the other hand, the resin compositions of Comparative Examples 1 to 6, which did not contain component (C), had poor solder heat resistance.

The resin composition of this embodiment has excellent heat resistance. Therefore, the resin composition of this embodiment is useful for applications such as multilayer printed wiring boards used in fifth-generation mobile communication system (5G) antennas, which use radio waves in frequency bands above 6 GHz, and millimeter-wave radar, which uses radio waves in the 30 to 300 GHz frequency band.

Claims (14)

(A) a thermosetting resin;
(B) a titanium-based inorganic filler;
(C) a titanate-based coupling agent;
A resin composition comprising:
The resin composition, wherein the (A) thermosetting resin is at least one selected from the group consisting of maleimide compounds having one or more N-substituted maleimide groups and derivatives thereof . 2. The resin composition according to claim 1, wherein the average particle size (D ₅₀ ) of the titanium-based inorganic filler (B) is 0.1 to 20 μm. The resin composition according to claim 1 or 2, wherein (B) the titanium-based inorganic filler is a titanate. The resin composition according to claim 3, wherein the titanate is one or more selected from the group consisting of barium titanate, potassium titanate, calcium titanate, strontium titanate, lead titanate, and aluminum titanate. The resin composition according to any one of claims 1 to 4 , further comprising (D) an inorganic filler having a lower relative dielectric constant (Dk) than the titanium-based inorganic filler (B). 6. The resin composition according to claim 5 , wherein (D) the inorganic filler having a lower dielectric constant (Dk) than the titanium-based inorganic filler (B) is at least one selected from the group consisting of silica and alumina. The resin composition according to any one of claims 1 to 6 , wherein the cured product has a relative dielectric constant (Dk) at 20 GHz of 2 to 50. The resin composition according to any one of claims 1 to 7 , which is used for an antenna module. A prepreg comprising the resin composition according to any one of claims 1 to 8 . A laminate comprising the prepreg according to claim 9 and a metal foil. A resin film comprising the resin composition according to any one of claims 1 to 8 . A multilayer printed wiring board comprising at least one member selected from the group consisting of the prepreg according to claim 9 , the laminate according to claim 10 , and the resin film according to claim 11 . An antenna device comprising the multilayer printed wiring board according to claim 12 . An antenna module comprising the antenna device according to claim 13 and a feeder circuit.