WO2023074646A1

WO2023074646A1 - Resin-coated metal foil, printed wiring board and manufacturing method thereof, and semiconductor package

Info

Publication number: WO2023074646A1
Application number: PCT/JP2022/039600
Authority: WO
Inventors: 香織佐々木; 圭芸日▲高▼; 淳生染川; 栞田端; 幸雄中村; 陽佳篠崎; 剛廣瀬
Original assignee: 株式会社レゾナック
Priority date: 2021-10-27
Filing date: 2022-10-25
Publication date: 2023-05-04
Also published as: TW202327874A

Abstract

The present invention relates to a resin-coated metal foil that has a first thermosetting resin layer containing an inorganic filler, a second thermosetting resin layer containing a rubber component, and a metal foil in this order, the content of the inorganic filler in the first thermosetting resin layer being 50-90% by mass, and the content of the inorganic filler in the second thermosetting resin layer being 0-20% by mass, and also relates to a printed wiring board using the resin-coated metal foil, a manufacturing method thereof, and a semiconductor package.

Description

METAL FOIL WITH RESIN, PRINTED WIRING BOARD AND MANUFACTURING METHOD THEREOF, AND SEMICONDUCTOR PACKAGE

The present embodiment relates to a resin-coated metal foil, a printed wiring board and its manufacturing method, and a semiconductor package.

2. Description of the Related Art In recent years, with the trend toward miniaturization and high performance of electronic devices, printed wiring boards are progressing toward higher wiring densities and higher integration.
Thermosetting resins are mainly used as insulating materials for printed wiring boards. Thermosetting resins are excellent in insulating properties, heat resistance, etc., but have a higher coefficient of thermal expansion than inorganic members such as semiconductor elements and circuits. may cause it to occur.
As a method of suppressing the occurrence of warpage, a method of highly filling a thermosetting resin with an inorganic filler has been performed (see, for example, Patent Document 1). By highly filling the inorganic filler with a small thermal expansion coefficient, it is possible to reduce the difference in thermal expansion coefficient between the insulating material containing the thermosetting resin and the inorganic member such as a semiconductor element, thereby suppressing warpage. It is possible.

Japanese Patent Application Laid-Open No. 2020-059820

By the way, as an insulating material for printed wiring boards, a resin-coated metal foil having a resin layer formed using a resin composition on a metal foil is sometimes used. The resin layer of the resin-coated metal foil is normally adjusted to a B-stage state, and forms an insulating layer by curing while embedding the circuit of the circuit board.

In metal foil with resin, high filling of inorganic fillers is also effective in reducing warpage. When the resin layer is B-staged in , there arises a problem that cracks occur in the resin layer. This is because curing shrinkage occurs when the resin composition is B-staged, and stress is generated between the metal foil and the interface between the inorganic fillers or between the inorganic filler and the resin component is destroyed by the stress. This is thought to be because Since the occurrence of such cracks is a factor in lowering the yield of products, it is desirable to suppress them.
Moreover, the occurrence of the above stress also causes curling of the resin-coated metal foil. Curling is desirably suppressed, because it can be a factor in lowering the handleability of the resin-coated metal foil and lowering the productivity of printed wiring boards using the resin-coated metal foil.

In view of such circumstances, the present embodiment provides a resin-coated metal foil in which the occurrence of cracks and curls in the resin layer is suppressed, a printed wiring board using the resin-coated metal foil, a method for manufacturing the same, and a semiconductor package. The task is to

The inventors of the present invention conducted studies to solve the above problems, and as a result, found that the above problems can be solved by the present embodiment described below.
That is, the present embodiment relates to the following [1] to [11].
[1] A first thermosetting resin layer containing an inorganic filler;
a second thermosetting resin layer containing a rubber component;
and a metal foil in this order,
The content of the inorganic filler in the first thermosetting resin layer is 50 to 90 mass%,
The content of the inorganic filler in the second thermosetting resin layer is 0 to 20% by mass,
Metal foil with resin.
[2] The first thermosetting resin layer is a layer formed from a first thermosetting resin composition containing a thermosetting resin and an inorganic filler,
The above [ 1].
[3] at least one type selected from the group consisting of maleimide resins having at least one N-substituted maleimide group and derivatives thereof is a structure derived from a maleimide resin having at least two N-substituted maleimide groups; The resin-coated metal foil according to [2] above, which is a resin containing a structure derived from a silicone compound having a group amino group.
[4] the second thermosetting resin layer is a layer formed from a second thermosetting resin composition containing a thermosetting resin and a rubber component;
The resin-coated metal foil according to any one of [1] to [3] above, wherein the thermosetting resin contained in the second thermosetting resin composition is an epoxy resin.
[5] The metal foil with resin according to [4] above, wherein the second thermosetting resin composition further contains a phenol resin-based curing agent.
[6] The resin-coated metal foil according to any one of [1] to [5] above, wherein the rubber component is crosslinked rubber particles.
[7] The resin-coated metal foil according to any one of [1] to [6] above, wherein the content of the inorganic filler in the second thermosetting resin layer is 0 to 5% by mass.
[8] The resin-coated metal foil according to any one of [1] to [7] above, wherein the metal foil is a copper foil.
[9] A printed wiring board formed using the resin-coated metal foil according to any one of [1] to [8] above,
a circuit board having a circuit on at least one side;
a cured material layer of the first thermosetting resin layer in which the circuit is embedded;
A cured product layer of the second thermosetting resin layer;
A printed wiring board, comprising a laminate structure having in that order:
[10] A semiconductor package formed using the printed wiring board according to [9] above.
[11] A method for manufacturing a printed wiring board according to [9] above,
A method of manufacturing a printed wiring board, wherein the circuit of the circuit board having the circuit on at least one surface is embedded with the first thermosetting resin layer of the metal foil with resin.

According to the present embodiment, it is possible to provide a resin-coated metal foil in which the occurrence of cracks and curls in the resin layer is suppressed, a printed wiring board using the resin-coated metal foil, a method for manufacturing the same, and a semiconductor package.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing showing the one aspect|mode of the metal foil with resin of this embodiment.

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

Each component and material exemplified in this specification may be used alone or in combination of two or more unless otherwise specified.
In the present specification, the content of each component in the resin composition refers to the content of the plurality of substances present in the resin composition when there are multiple substances corresponding to each component in the resin composition, unless otherwise specified. means the total amount of
As used herein, the term "resin composition" includes a mixture of each component described below and a semi-cured product of the mixture.

As used herein, the term "solid content" means components other than the solvent, including those that are liquid at room temperature, starch syrup, and wax. Here, in this specification, room temperature means 25°C.

"(Meth)acrylate" as used herein means "acrylate" and its corresponding "methacrylate". Similarly, "(meth)acrylic" means "acrylic" and corresponding "methacrylic", and "(meth)acryloyl" means "acryloyl" and corresponding "methacryloyl".

In the present specification, when the term "layer" is used, in addition to the solid layer, it is not a solid layer, but is partially island-shaped, has holes, and is adjacent to the layer. The "layer" also includes a mode in which the interface between is unclear.

The number average molecular weight (Mn) and weight average molecular weight (Mw) in this specification mean values measured in terms of polystyrene by gel permeation chromatography (GPC; Gel Permeation Chromatography). Specifically, the number average molecular weight (Mn) and weight average molecular weight (Mw) in this specification can be measured by methods described in Examples.

The mechanism of action described in this specification is speculation, and does not limit the mechanism that produces the effects of this embodiment.

Aspects in which the items described in this specification are arbitrarily combined are also included in the present embodiment.

[Metal foil with resin]
The metal foil with resin of this embodiment is
a first thermosetting resin layer containing an inorganic filler;
a second thermosetting resin layer containing a rubber component;
and a metal foil in this order,
The content of the inorganic filler in the first thermosetting resin layer is 50 to 90 mass%,
The content of the inorganic filler in the second thermosetting resin layer is 0 to 20% by mass,
It is a metal foil with resin.

FIG. 1 shows a schematic cross-sectional view of a resin-coated metal foil 1, which is one aspect of the resin-coated metal foil of this embodiment.
The resin-coated metal foil 1 has a second thermosetting resin layer 3 on one surface of the metal foil 2, and the surface of the second thermosetting resin layer 3 opposite to the metal foil 2 has A first thermosetting resin layer 4 is provided.
Each configuration of the resin-coated metal foil of this embodiment will be described below.

<First thermosetting resin layer>
The first thermosetting resin layer is a thermosetting resin layer containing an inorganic filler.
The first thermosetting resin layer is usually laminated on the circuit of the circuit board and melted and cured by heating to form a cured material layer in which the circuit is embedded. In addition, when there are through holes, via holes, etc. on the circuit board, the fluid may flow into these holes and fill the holes.
In this specification, the term "thermosetting resin layer" means a resin layer having thermosetting properties, and the term "resin layer" means a layer containing a resin.

In the metal foil with resin of this embodiment, the content of the inorganic filler in the first thermosetting resin layer is 50 to 90% by mass.
When the content of the inorganic filler in the first thermosetting resin layer is at least the above lower limit, excellent low thermal expansion and heat resistance can be obtained. Moreover, when the content of the inorganic filler in the first thermosetting resin layer is equal to or less than the above upper limit value, excellent moldability and conductor adhesion can be obtained.
From the same point of view, the content of the inorganic filler in the first thermosetting resin layer is not particularly limited, but is preferably 50 to 80% by mass, more preferably 50 to 75% by mass, and still more preferably 50 to 75% by mass. 70% by mass. Further, the content of the inorganic filler in the first thermosetting resin layer may be 55 to 80% by mass, may be 60 to 75% by mass, or may be 65 to 70% by mass. good too. Suitable types of inorganic fillers are described below.

Although the thickness of the first thermosetting resin layer is not particularly limited, it is preferably 4 to 100 μm, more preferably 6 to 60 μm, still more preferably 8 to 40 μm.
When the thickness of the first thermosetting resin layer is at least the above lower limit, the circuit embedding property tends to be more favorable. Further, when the thickness of the first thermosetting resin layer is equal to or less than the above upper limit value, it tends to be preferable due to high wiring density.

The first thermosetting resin layer is preferably a layer formed from a first thermosetting resin composition containing a thermosetting resin and an inorganic filler.
Next, each component that the first thermosetting resin composition may contain will be described. In the following description, the thermosetting resin contained in the first thermosetting resin composition is "thermosetting resin (A)", and the inorganic filler contained in the first thermosetting resin composition The material may be referred to as "inorganic filler (B)".

(Thermosetting resin (A))
Examples of thermosetting resins (A) include epoxy resins, phenol resins, maleimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, Examples include silicone resins, triazine resins, melamine resins, and the like. Among these, from the viewpoint of heat resistance, maleimide resins, epoxy resins, and cyanate resins are preferred, maleimide resins and epoxy resins are more preferred, and maleimide resins are even more preferred.
The thermosetting resin (A) may be used alone or in combination of two or more.

[Maleimide resin]
The maleimide resin is preferably one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof.
That is, the first thermosetting resin layer is a layer formed from a first thermosetting resin composition containing a thermosetting resin and an inorganic filler, and the first thermosetting resin composition The contained thermosetting resin is preferably one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof.
The one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof include maleimide resins having two or more N-substituted maleimide groups (hereinafter referred to as "maleimide resin (A1)" Also referred to as), a resin containing a structure derived from a maleimide resin having two or more N-substituted maleimide groups and a structure derived from a silicone compound having a primary amino group (hereinafter referred to as "silicone-modified maleimide resin (A2)" Also referred to as) is preferable, and from the viewpoint of heat resistance and low thermal expansion, the silicone-modified maleimide resin (A2) is more preferable. In addition, in this embodiment, the silicone-modified maleimide resin (A2) is one aspect of the maleimide resin.

<<Maleimide resin (A1)>>
As the maleimide resin (A1), a compound represented by the following general formula (A1-1) is preferable.

(In the formula, X ^A11 is a divalent organic group.)

X ^A11 in general formula (A1-1) above is a divalent organic group.
The divalent organic group represented by X ^A11 in the general formula (A1-1) includes, for example, a divalent group represented by the following general formula (A1-2), and a divalent group represented by the following general formula (A1-3). a divalent group represented by the following general formula (A1-4), a divalent group represented by the following general formula (A1-5), a following general formula (A1-6) A divalent group represented by is mentioned.

(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 the general formula (A1-2) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl t-butyl group, n-pentyl group and other alkyl groups having 1 to 5 carbon atoms; 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. 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 further preferably a methyl group.
Halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.
n ^A11 in the general formula (A1-2) is an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, still more preferably 0, from the viewpoint of availability.
When n ^A11 is an integer of 2 or more, the plurality of R ^A11 may be the same or different.

(wherein R ^A12 and R ^A13 are each independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; X ^A12 is an alkylene group having 1 to 5 carbon atoms; ^{n A12} and n ^A13 are an alkylidene group, 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). , each independently an integer from 0 to 4. * represents a binding site.)

Examples of aliphatic hydrocarbon groups having 1 to 5 carbon atoms represented by R ¹² and R ¹³ in general formula (A1-3) include methyl, ethyl, n-propyl, isopropyl and n-butyl. alkyl groups having 1 to 5 carbon atoms such as isobutyl group, t-butyl group and n-pentyl group; 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. 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 further preferably a methyl group or an ethyl group.
Halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.

Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^A12 in the above general formula (A1-3) include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group and a 1,4-tetramethylene group. group, 1,5-pentamethylene group, and the like. 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 still more preferably a methylene group.

The alkylidene group having 2 to 5 carbon atoms represented by X ^A12 in the general formula (A1-3) includes, for example, an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group and 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.

n ^A12 and n ^A13 in general formula (A1-3) are each independently an integer of 0 to 4.
When n ^A12 or n ^A13 is an integer of 2 or more, the plurality of ^RA12s or the plurality of ^RA13s may be the same or different.

The divalent group represented by general formula (A1-3-1) represented by X ^A12 in general formula (A1-3) is as follows.

(wherein R ^A14 and R ^A15 are each independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; X ^A13 is an alkylene group having 1 to 5 carbon atoms; an alkylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group or a single bond, ^nA14 and ^nA15 are each independently an integer of 0 to 4. * represents a binding site. )

Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^A14 and R ^A15 in the general formula (A1-3-1) include methyl group, ethyl group, n-propyl group, isopropyl group, n C1-5 alkyl groups such as -butyl group, isobutyl group, t-butyl group and n-pentyl group; C2-5 alkenyl groups and C2-5 alkynyl groups. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be 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 further preferably a methyl group.
Halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.

Examples of the alkylene group having 1 to 5 carbon atoms represented by X ^A13 in the general formula (A1-3-1) include methylene group, 1,2-dimethylene group, 1,3-trimethylene group, 1,4- A tetramethylene group, a 1,5-pentamethylene group and the like can be mentioned. 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 still more preferably a methylene group.

Examples of the alkylidene group having 2 to 5 carbon atoms represented by X ^A13 in the general formula (A1-3-1) include ethylidene group, propylidene group, isopropylidene group, butylidene group, isobutylidene group, pentylidene group, isopentyl A lidene group and the like can be mentioned. 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 the 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 further an isopropylidene group. preferable.

n ^A14 and n ^A15 in the general formula (A1-3-1) are each independently an integer of 0 to 4, and from the viewpoint of availability, both are preferably integers of 0 to 2, and more It is preferably 0 or 1, more preferably 0.
When n ^A14 or n ^A15 is an integer of 2 or more, the plurality of R ^A14 or the plurality of R ^A15 may be the same or different.

As X ^A12 in the 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, and the above general formula (A1-3-1) is preferred, an alkylene group having 1 to 5 carbon atoms is more preferred, and a methylene group is even more preferred.

(Wherein, n ^A16 is an integer from 0 to 10. * represents a binding site.)

n ^A16 in the general formula (A1-4) is preferably an integer of 0 to 5, more preferably an integer of 0 to 4, and still more preferably an integer of 0 to 3, from the viewpoint of availability.

(Wherein, n ^A17 is a number from 0 to 5. * represents a binding site.)

(In the formula, R ^A16 and R ^A17 are each independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms. ^{n A18} is an integer of 1 to 8. * represents a bonding site. )

The aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ¹⁶ and R ¹⁷ in general formula (A1-6) includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl alkyl groups having 1 to 5 carbon atoms such as isobutyl group, t-butyl group and n-pentyl group; 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.
n ^A18 in the general formula (A1-6) is an integer of 1 to 8, preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and still more preferably 1. When n ^A18 is an integer of 2 or more, the plurality of R ^A16 or the plurality of R ^A17 may be the same or different.

Examples of the maleimide resin (A1) include aromatic bismaleimide resins, aromatic polymaleimide resins, and aliphatic maleimide resins.
As used herein, the term "aromatic bismaleimide resin" means a compound having two N-substituted maleimide groups directly bonded to an aromatic ring. Further, the term "aromatic polymaleimide resin" as used herein means a compound having 3 or more N-substituted maleimide groups directly bonded to an aromatic ring. Further, the term "aliphatic maleimide resin" as used herein means a compound having an N-substituted maleimide group directly bonded to an aliphatic hydrocarbon.

Specific examples of the maleimide resin (A1) include N,N'-ethylenebismaleimide, N,N'-hexamethylenebismaleimide, 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-maleimide phenyl)ether, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl)sulfide, bis(4-maleimidophenyl)ketone, bis(4-maleimidocyclohexyl)methane, 1,4-bis(4-maleimidophenyl) ) cyclohexane, 1,4-bis(maleimidomethyl)cyclohexane, 1,4-bis(maleimidomethyl)benzene, 1,3-bis(4-maleimidophenoxy)benzene, 1,3-bis(3-maleimidophenoxy)benzene , bis[4-(3-maleimidophenoxy)phenyl]methane, bis[4-(4-maleimidophenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,1 -bis[4-(4-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(4-maleimidophenoxy)phenyl]ethane , 2,2-bis[4-(3-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidophenoxy) ) phenyl]butane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3, 3-hexafluoropropane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4-bis(3-maleimidophenoxy) Biphenyl, 4,4-bis(4-maleimidophenoxy)biphenyl, bis[4-(3-maleimidophenoxy)phenyl]ketone, bis[4-(4-maleimidophenoxy)phenyl]ketone, bis(4-maleimidophenyl) Disulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfide, bis[4-(4-maleimidophenoxy)phenyl]sulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfoxide, bis[4-(4 -maleimidophenoxy)phenyl]sulfoxide, bis[4-(3-maleimidophenoxy)phenyl]sulfone, bis[4-(4-maleimidophenoxy)phenyl]sulfone, bis[4-(3-maleimidophenoxy)phenyl]ether, bis[4-(4-maleimidophenoxy)phenyl] ether, 1,4-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimide phenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy) -α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4 -maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, polyphenylmethane maleimide, biphenylaralkyl type maleimide and the like. Among these, bis(4-maleimidophenyl)methane is preferred.

<<Silicone modified maleimide resin (A2)>>
The silicone-modified maleimide resin (A2) is a resin containing a structure derived from a maleimide resin having two or more N-substituted maleimide groups and a structure derived from a silicone compound having a primary amino group.

The structure derived from a maleimide resin having two or more N-substituted maleimide groups includes, for example, among the N-substituted maleimide groups possessed by the maleimide resin (A1), at least one N-substituted maleimide group is a primary amino group. A structure formed by a Michael addition reaction with a primary amino group of a silicone compound having
The structure derived from the maleimide resin (A1) contained in the silicone-modified maleimide resin (A2) may be one type alone or two or more types.

The content of the structure derived from the maleimide resin (A1) in the silicone-modified maleimide resin (A2) is not particularly limited, but is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and still more preferably 20 to 40%. % by mass.
When the content of the structure derived from the maleimide resin (A1) is at least the above lower limit, the heat resistance tends to be better. Moreover, when the content of the structure derived from the maleimide resin (A1) is equal to or less than the above upper limit, the low thermal expansion property tends to be more favorable.

As the structure derived from the silicone compound having a primary amino group, for example, the primary amino group possessed by the silicone compound having a primary amino group is an N-substituted maleimide group possessed by the maleimide resin (A1) and Michael addition. A structure formed by reaction can be mentioned.
The structure derived from the silicone compound having a primary amino group contained in the silicone-modified maleimide resin (A2) may be one type alone or two or more types.

The number of primary amino groups in the silicone compound having primary amino groups is preferably 1 to 4, more preferably 2 to 3, still more preferably 2.
The silicone compound having a primary amino group may have the primary amino group in the side chain or at the end, but preferably at the end.
The silicone compound having a primary amino group may have a primary amino group at one end or at both ends, preferably at both ends.

The silicone compound having a primary amino group is preferably a compound containing a structure represented by general formula (A2-1) below, and is a compound represented by general formula (A2-2) below. is more preferred.

(In the formula, R ^A21 and R ^A22 are each independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms, a phenyl group or a substituted phenyl group. * represents a bonding site.)

(Wherein, R ^A21 and R ^A22 are the same as those in the above general formula (A2-1), R ^A23 and R ^A24 are each independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms, a phenyl group or a substituted phenyl group, X ^A21 and X ^A22 are each independently a divalent organic group, and n ^A21 is an integer of 1 to 100.)

Examples of aliphatic hydrocarbon groups having 1 to 5 carbon atoms represented by R ^A21 to R ^A24 in general formulas (A2-1) and (A2-2) include methyl group, ethyl group, n-propyl group, C1-5 alkyl groups such as isopropyl group, n-butyl group, isobutyl group, t-butyl group and n-pentyl group; C2-5 alkenyl groups, C2-5 alkynyl groups, etc. mentioned. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be 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 further preferably a methyl group.
Examples of substituents possessed by the phenyl groups in the substituted phenyl groups represented by R ^A21 to R ^A24 include the aforementioned aliphatic hydrocarbon groups having 1 to 5 carbon atoms.

Examples of the divalent organic group represented by X ^A21 and X ^A22 include an alkylene group, an alkenylene group, an alkynylene group, an arylene group, —O—, and a divalent linking group in which these are combined.
Examples of the alkylene group include alkylene groups having 1 to 10 carbon atoms such as a methylene group, ethylene group and propylene group.
Examples of the alkenylene group include alkenylene groups having 2 to 10 carbon atoms.
Examples of the alkynylene group include alkynylene groups having 2 to 10 carbon atoms.
Examples of the arylene group include arylene groups having 6 to 20 carbon atoms such as phenylene group and naphthylene group.
Among these, X ^A21 and X ^A22 are preferably an alkylene group or an arylene group, and more preferably an alkylene group.

^nA21 is an integer of 1-100, preferably an integer of 2-50, more preferably an integer of 3-40, and still more preferably an integer of 5-30. When n ^A21 is an integer of 2 or more, the plurality of ^RA21s or the plurality of ^RA22s may be the same or different.

The primary amino group equivalent weight of the silicone compound having a primary amino group is not particularly limited, but is preferably 200 to 1,000 g/mol, more preferably 250 to 700 g/mol, still more preferably 300 to 500 g/mol. is.

The content of the structure derived from the silicone compound having a primary amino group in the silicone-modified maleimide resin (A2) is not particularly limited, but is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and still more preferably. is 55 to 75% by mass.
When the content of the structure derived from the silicone compound having a primary amino group is at least the above lower limit, the low thermal expansion property tends to be more favorable. Moreover, when the content of the structure derived from the silicone compound having a primary amino group is equal to or less than the above upper limit, the heat resistance tends to be more favorable.

The silicone-modified maleimide resin (A2) preferably further contains a structure derived from an amine compound having an acidic substituent.
The structure derived from the amine compound having an acidic substituent contained in the silicone-modified maleimide resin (A2) may be one type alone or two or more types.

The amine compound having an acidic substituent is preferably a compound having an acidic substituent and a primary amino group, more preferably an aromatic compound having an acidic substituent and a primary amino group, represented by the following general formula (A2-3 ) is more preferred.

(In the formula, R ^A25 is a hydroxyl group, a carboxy group or a sulfonic acid group, R ^A26 is an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom, n ^A22 is an integer of 1 to 5, n ^A23 is an integer of 0 to 5, and the sum of ^nA22 and ^nA23 is an integer of 1 to 5.)

R ^A25 in general formula (A2-3) above is a hydroxyl group, a carboxy group or a sulfonic acid group, preferably a carboxy group.
Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by R ^A26 in the general formula (A2-3) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl t-butyl group, n-pentyl group and other alkyl groups having 1 to 5 carbon atoms; 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. 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 further preferably a methyl group.
Examples of the halogen atom represented by R ^{1 A26} in the general formula (A2-3) include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.
n ^A22 in the general formula (A2-3) is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, still more preferably 1, from the viewpoint of availability.
n ^A23 in the general formula (A2-3) is an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 1, still more preferably 0, from the viewpoint of availability.
The sum of n ^A22 and n ^A23 in the general formula (A2-3) is an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, and still more preferably, from the viewpoint of availability. is 1.

Examples of amine compounds having an acidic substituent include aminophenols such as o-aminophenol, m-aminophenol and p-aminophenol; p-aminobenzoic acid, m-aminobenzoic acid and o-aminobenzoic acid. aminobenzoic acid; aminobenzenesulfonic acids such as o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid and p-aminobenzenesulfonic acid; 3,5-dihydroxyaniline, 3,5-dicarboxyaniline and the like. Among these, aminophenol, aminobenzoic acid and 3,5-dihydroxyaniline are preferable from the viewpoint of solubility and synthesis yield, and m-aminophenol and p-aminophenol are more preferable from the viewpoint of heat resistance.

The content of the structure derived from the amine compound having an acidic substituent in the silicone-modified maleimide resin (A2) is not particularly limited, but is preferably 0.1 to 4% by mass, more preferably 0.5 to 2% by mass. , more preferably 0.8 to 1.5% by mass.
When the content of the structure derived from the amine compound having an acidic substituent is at least the above lower limit, the heat resistance and conductor adhesion tend to be better. Moreover, when the content of the structure derived from the amine compound having an acidic substituent is equal to or less than the above upper limit, the heat resistance tends to be more favorable.

The silicone-modified maleimide resin (A2) may contain a structure derived from a compound (C) having at least two primary amino groups in one molecule, which will be described later.

The silicone-modified maleimide resin (A2) can be produced, for example, by reacting the maleimide resin (A1) with a silicone compound having a primary amino group. and an amine compound having an acidic substituent are preferably reacted.
A suitable blending amount of each component is such that the content of the structure derived from each component in the resulting silicone-modified maleimide resin (A2) is within the above range.

The above reaction is preferably carried out in an organic solvent. Examples of the organic solvent include the same organic solvents as those that may be contained in the first thermosetting resin composition described later. Among these, propylene glycol monomethyl ether is preferred.
The reaction temperature for the above reaction is not particularly limited, but is preferably 50 to 160°C, more preferably 60 to 150°C, and still more preferably 70 to 140°C from the viewpoint of obtaining an appropriate reaction rate.
The reaction time for the above reaction is not particularly limited, but from the viewpoint of productivity, it is preferably 0.5 to 12 hours, more preferably 1 to 10 hours, and even more preferably 4 to 8 hours.
However, these reaction conditions are not particularly limited and can be appropriately adjusted depending on the type of raw material used.
When carrying out the above reaction, a reaction catalyst may or may not be used as necessary.

When the thermosetting resin (A) contains a maleimide resin, the content of the maleimide resin in the thermosetting resin (A) is not particularly limited, but is preferably 40 to 98% by mass, more preferably 60 to 95% by mass. % by mass, more preferably 80 to 90% by mass.
When the content of the maleimide resin in the thermosetting resin (A) is at least the above lower limit, the heat resistance tends to be better. Moreover, when the content of the maleimide resin in the thermosetting resin (A) is equal to or less than the above upper limit, the electrical properties tend to be more favorable.

〔Epoxy resin〕
The epoxy resin used as the thermosetting resin (A) is preferably an epoxy resin having two or more epoxy groups. Epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, and the like. Among these, glycidyl ether type epoxy resins are preferred.

Epoxy resins are classified into various epoxy resins depending on the difference in the main skeleton.
Specifically, epoxy resins include, for example, bisphenol-based epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol S-type epoxy resin; Bisphenol-based novolak-type epoxy resins; novolac-type epoxy resins other than the above bisphenol-based novolac-type epoxy resins, such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and biphenyl novolac-type epoxy resins; phenol aralkyl-type epoxy resins; stilbene-type epoxy resins Resin; naphthol novolac type epoxy resin, naphthol type epoxy resin, naphthol aralkyl type epoxy resin, naphthylene ether type epoxy resin, and other naphthalene skeleton-containing epoxy resins; biphenyl type epoxy resin; biphenyl aralkyl type epoxy resin; xylylene type epoxy resin; Anthracene type epoxy resin; alicyclic epoxy resin such as saturated dicyclopentadiene type epoxy resin; heterocyclic epoxy resin; spiro ring-containing epoxy resin; cyclohexanedimethanol type epoxy resin; trimethylol type epoxy resin; resin; rubber-modified epoxy resin; Among these, biphenyl aralkyl type epoxy resins are preferred.

Although the epoxy group equivalent weight of the epoxy resin is not particularly limited, it is preferably 150 to 600 g/mol, more preferably 200 to 450 g/mol, still more preferably 250 to 350 g/mol.

When the thermosetting resin (A) contains an epoxy resin, the content of the epoxy resin in the thermosetting resin (A) is not particularly limited, but is preferably 2 to 60% by mass, more preferably 5 to 40% by mass. % by mass, more preferably 10 to 20% by mass.
When the content of the epoxy resin in the thermosetting resin (A) is at least the above lower limit, moldability tends to be better. Moreover, when the content of the epoxy resin in the thermosetting resin (A) is equal to or less than the above upper limit, the heat resistance tends to be more favorable.

[Content of thermosetting resin (A)]
The content of the thermosetting resin (A) in the first thermosetting resin composition is not particularly limited, but the total amount of resin components in the first thermosetting resin composition (100% by mass) , preferably 30 to 95% by mass, more preferably 50 to 90% by mass, still more preferably 70 to 85% by mass.
When the content of the thermosetting resin (A) in the first thermosetting resin composition is at least the above lower limit, heat resistance, moldability and conductor adhesion tend to be better. Moreover, when the content of the thermosetting resin (A) in the first thermosetting resin composition is equal to or less than the above upper limit, it tends to be easy to adjust the balance of various properties well.

As used herein, the term "resin component" means a resin and a compound that forms a resin through a curing reaction.
For example, in the first thermosetting resin composition, the thermosetting resin (A) corresponds to the resin component. Further, when the first thermosetting resin composition contains, as an optional component, a resin or a compound that forms a resin by a curing reaction in addition to the thermosetting resin (A), these optional components are also included in the resin component. be Optional components corresponding to resin components include compounds (C) having at least two primary amino groups in one molecule, styrene elastomers (D), polyamide resins (E), curing accelerators (F ) and the like.

The total content of the resin components in the first thermosetting resin composition is not particularly limited, but the total solid content (100% by mass) of the first thermosetting resin composition is preferably 20 to 45% by mass, more preferably 25 to 40% by mass, still more preferably 30 to 35% by mass.
When the content of the resin component in the first thermosetting resin composition is at least the above lower limit, heat resistance, moldability and conductor adhesion tend to be better. Moreover, when the content of the resin component in the first thermosetting resin composition is equal to or less than the above upper limit, the low thermal expansion tends to be more favorable.

(Inorganic filler (B))
The first thermosetting resin composition contains an inorganic filler (B).
The inorganic filler (B) may be used alone or in combination of two or more.

Examples of the inorganic filler (B) include silica, alumina, titanium oxide, mica, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, silicon aluminum oxide, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, aluminum borate, silicon carbide and the like. Among these, silica, alumina, mica, and talc are preferred, silica and alumina are more preferred, and silica is even more preferred, from the viewpoints of low thermal expansion, heat resistance, and flame retardancy.

Silica includes, for example, precipitated silica that is produced by a wet method and has a high water content, and dry-process silica that is produced by a dry method and contains almost no bound water. Examples of dry process silica include crushed silica, fumed silica, fused silica, etc., depending on the production method.

Although the average particle size of the inorganic filler (B) is not particularly limited, it is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm, from the viewpoint of the dispersibility and fine wiring properties of the inorganic filler (B). , more preferably 0.2 to 1 μm, particularly preferably 0.3 to 0.8 μm.
In this specification, the average particle size is the particle size at the point corresponding to 50% volume when the cumulative frequency distribution curve of the particle size is obtained with the total volume of the particles being 100%.
The average particle size of the inorganic filler (B) can be measured, for example, with a particle size distribution analyzer using a laser diffraction scattering method.
Examples of the shape of the inorganic filler (B) include a spherical shape and a crushed shape, and a spherical shape is preferred.

A coupling agent may be used in the first thermosetting resin composition for the purpose of improving the dispersibility of the inorganic filler (B) and the adhesion with the organic component. Examples of coupling agents include silane coupling agents and titanate coupling agents. Among these, silane coupling agents are preferred. Silane coupling agents include, for example, aminosilane coupling agents, vinylsilane coupling agents, and epoxysilane coupling agents.

When a coupling agent is used in the first thermosetting resin composition, the surface treatment method for the inorganic filler (B) is to mix the inorganic filler (B) in the resin composition and then add the coupling agent. Although an integral blend treatment method may be used, a method in which the inorganic filler (B) is surface-treated in advance with a coupling agent in a dry or wet manner is preferable.
For the purpose of improving dispersibility, the inorganic filler (B) may be previously dispersed in an organic solvent to form a slurry, and then mixed with other components.

The content of the inorganic filler (B) in the first thermosetting resin composition is such that the content of the inorganic filler (B) in the first thermosetting resin layer is within the range described above. .

(Compound (C) having at least two primary amino groups in one molecule)
The first thermosetting resin composition preferably further contains a compound (C) having at least two primary amino groups in one molecule (hereinafter also referred to as "diamine compound (C)"). . As described above, the diamine compound (C) may be used as a raw material for the silicone-modified maleimide resin (A2).
A diamine compound (C) may be used individually by 1 type, and may use 2 or more types together.

A compound represented by the following general formula (C-1) is preferable as the diamine compound (C).

(In the formula, X ^C1 is a divalent organic group.)

X ^C1 in general formula (C-1) above is preferably a divalent group represented by general formula (C-2) below.

(In the formula, R ^C1 and R ^C2 are each independently 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 ^C2 is 1 carbon atom; -5 alkylene group, C2-5 alkylidene group, ether group, sulfide group, sulfonyl group, carbonyloxy group, keto group, fluorenylene group, single bond, or general formula (C-2-1) below or below It is a divalent group represented by the general formula (C-2-2).n ^C1 and n ^C2 are each independently an integer of 0 to 4. * represents a binding site.)

(wherein R ^C3 and R ^C4 are each independently an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; X ^C3 is an alkylene group having 1 to 5 carbon atoms; an alkylidene group, a 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, ^nC3 and ^nC4 are each independently , an integer from 0 to 4. * represents a binding site.)

(In the formula, R ^C5 is an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom; X ^C4 and X ^C5 each independently represent an alkylene group having 1 to 5 carbon atoms; is an alkylidene group, an ether group, a sulfide group, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond.n ^C5 is an integer of 0 to 4. * represents a bonding site.)

Number of carbon atoms represented by R ^C1 , R ^C2 , R ^C3 , R ^C4 and R ^C5 in general formula (C-2), general formula (C-2-1) and general formula (C-2-2) Examples of 1 to 5 aliphatic hydrocarbon groups include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group and the like. to 5 alkyl 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. 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 further preferably a methyl group or an ethyl group.
Halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.

The number of carbon atoms represented by X ^C2 in the general formula (C-2), X ^C3 in the general formula (C-2-1), and X ^C4 and X ^C5 in the general formula (C-2-2) is 1 Examples of the alkylene group of 1 to 5 include methylene group, 1,2-dimethylene group, 1,3-trimethylene group, 1,4-tetramethylene group, 1,5-pentamethylene group and the like. 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 still more preferably a methylene group.

The number of carbon atoms represented by X ^C2 in the general formula (C-2), X ^C3 in the general formula (C-2-1), and X ^C4 and X ^C5 in the general formula (C-2-2) Examples of alkylidene groups of 2 to 5 include ethylidene group, propylidene group, isopropylidene group, butylidene group, isobutylidene group, pentylidene group, isopentylidene group and the like. 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 still more preferably an isopropylidene group.

n ^C1 and n ^C2 in the general formula (C-2) are each independently an integer of 0 to 4, and from the viewpoint of availability, both are preferably integers of 0 to 3, more preferably It is an integer from 0 to 2, more preferably 0 or 2.
When n ^C1 or n ^C2 is an integer of 2 or more, the plurality of R ^C1 or the plurality of R ^C2 may be the same or different.

n ^C3 and n ^C4 in the general formula (C-2-1) are each independently an integer of 0 to 4, and from the viewpoint of availability, both are preferably integers of 0 to 2, and more It is preferably 0 or 1, more preferably 0.
When n ^C3 or n ^C4 is an integer of 2 or more, the plurality of R ^C3s or the plurality of R ^C4s may be the same or different.

n ^C5 in the general formula (C-2-2) is an integer of 0 to 4, and from the viewpoint of availability, preferably an integer of 0 to 2, more preferably 0 or 1, more preferably 0 is.
When n ^C5 is an integer of 2 or more, the plurality of R ^C5 may be the same or different.

Examples of the diamine compound (C) include aliphatic diamine compounds and aromatic diamine compounds, among which aromatic diamine compounds are preferred from the viewpoint of heat resistance.
In this specification, the term "aliphatic diamine compound" means a compound having two amino groups directly bonded to an aliphatic hydrocarbon, and the term "aromatic diamine compound" means a compound that directly binds to an aromatic hydrocarbon. It means a compound having two binding amino groups.

Examples of aromatic diamine compounds include 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4 '-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4 '-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3'- dimethyl-5,5′-diethyl-4,4′-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1, 3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl , 1,3-bis[1-[4-(4-aminophenoxy)phenyl]-1-methylethyl]benzene, 1,4-bis[1-[4-(4-aminophenoxy)phenyl]-1- methylethyl]benzene, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, 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, 9,9- bis(4-aminophenyl)fluorene and the like.

Among these, the diamine compound (C) is 4,4′-diaminodiphenylmethane, 3,3′-dimethyl, and is excellent in solubility in organic solvents, reactivity, heat resistance, dielectric properties and low water absorption. -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, 4,4′-[1,4-phenylenebis(1-methylethylidene)]bisaniline are preferred, and 3,3′-diethyl-4,4′-diaminodiphenylmethane is more preferred.

[Content of diamine compound (C)]
When the first thermosetting resin composition contains the diamine compound (C), the content of the diamine compound (C) in the first thermosetting resin composition is not particularly limited. It is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 3 to 7% by mass, relative to the total amount (100% by mass) of the resin components in the curable resin composition.
When the content of the diamine compound (C) in the first thermosetting resin composition is at least the above lower limit, the heat resistance tends to be better. Moreover, when the content of the diamine compound (C) in the first thermosetting resin composition is equal to or less than the above upper limit, it tends to be easy to adjust the balance of various properties well.

(Styrene-based elastomer (D))
The first thermosetting resin composition preferably further contains a styrene elastomer (D).
The styrene-based elastomer (D) may be used alone or in combination of two or more.

As the styrene-based elastomer (D), one having a structural unit derived from a styrene-based compound represented by the following general formula (D-1) is preferable.

(In the formula, R ^D1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ^D2 is an alkyl group having 1 to 5 carbon atoms, and ^{n D1} is an integer of 0 to 5.)

Examples of the alkyl group having 1 to 5 carbon atoms represented by R ^D1 and R ^D2 in the general formula (D-1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl. group, t-butyl group, n-pentyl group and the like. Alkyl groups having 1 to 5 carbon atoms may be linear or branched. Among these, an alkyl group having 1 to 3 carbon atoms is preferred, an alkyl group having 1 or 2 carbon atoms is more preferred, and a methyl group is even more preferred.
n ^D1 in the general formula (D-1) is an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 1, still more preferably 0.

The styrene-based elastomer (D) may contain structural units other than structural units derived from styrene-based compounds.
Structural units other than the styrene-based compound-derived structural units possessed by the styrene-based elastomer (D) include, for example, butadiene-derived structural units, isoprene-derived structural units, maleic acid-derived structural units, and maleic anhydride-derived structural units. etc.
The butadiene-derived structural unit and the isoprene-derived structural unit may be hydrogenated. When hydrogenated, structural units derived from butadiene become structural units in which ethylene units and butylene units are mixed, and structural units derived from isoprene become structural units in which ethylene units and propylene units are mixed.

Examples of the styrene elastomer (D) include hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers, styrene-maleic anhydride copolymers, and the like. be done.
Hydrogenated products of styrene-butadiene-styrene block copolymers are SEBS obtained by completely hydrogenating the carbon-carbon double bonds in the butadiene block, and SBBS obtained by partially hydrogenating a heavy bond can be mentioned. In addition, complete hydrogenation in SEBS usually means that the hydrogenation rate of the entire carbon-carbon double bond is 90% or more, may be 95% or more, or may be 99% or more. It may be 100%. Also, the partial hydrogenation rate in SBBS is, for example, 60 to 85% with respect to the entire carbon-carbon double bond. A hydrogenated styrene-isoprene-styrene block copolymer is obtained as SEPS by hydrogenating the polyisoprene portion.
Among these, SEBS and SEPS are preferred, and SEBS is more preferred, from the viewpoint of dielectric properties, conductor adhesion, heat resistance, glass transition temperature and low thermal expansion.

In the styrene elastomer (D), the content of structural units derived from styrene (hereinafter also referred to as "styrene content") is not particularly limited, but is preferably 5 to 60 mol%, more preferably 10 to 50 mol%. , more preferably 20 to 40 mol %.

Examples of commercially available styrene elastomers (D) include Tuftec (registered trademark) H series and M series manufactured by Asahi Kasei Corporation, Septon (registered trademark) series manufactured by Kuraray Co., Ltd., and Kraton manufactured by Kraton Polymer Japan Co., Ltd. (registered trademark) G polymer series and the like.

The styrene elastomer (D) may be acid-modified with maleic anhydride or the like. The acid value of the acid-modified styrene elastomer (D) is not particularly limited, but is preferably 2 to 20 mg CH ₃ ONa/g, more preferably 5 to 15 mg CH ₃ ONa/g, and still more preferably 7 to 13 mg CH ₃ ONa/g. is g.

The number average molecular weight (Mn) of the styrene elastomer (D) is not particularly limited, but is preferably 10,000 to 500,000, more preferably 30,000 to 350,000, still more preferably 50,000 to 100, 000.

[Content of styrene elastomer (D)]
When the first thermosetting resin composition contains the styrene-based elastomer (D), the content of the styrene-based elastomer (D) in the first thermosetting resin composition is not particularly limited. With respect to the total amount (100% by mass) of the resin components in the thermosetting resin composition, preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, more preferably 3 to 7% by mass. be.
When the content of the styrene-based elastomer (D) in the first thermosetting resin composition is at least the above lower limit, the dielectric properties tend to be better. Moreover, when the content of the styrene-based elastomer (D) in the first thermosetting resin composition is equal to or less than the above upper limit, there is a tendency to favorably adjust the balance of various properties.

(Polyamide resin (E))
The first thermosetting resin composition preferably further contains a polyamide resin (E).
The polyamide resin (E) may be used alone or in combination of two or more.

The polyamide resin (E) is preferably a polyamide resin containing a polybutadiene skeleton, a structural unit represented by the following general formula (E-1), a structural unit represented by the following general formula (E-2) and the following general A polyamide resin containing a structural unit represented by formula (E-3) (hereinafter also referred to as “modified polyamide resin”) is more preferred.

In the general formulas (E-1) to (E-3), n ^E1 , n ^E2 , n ^E3 , n ^E4 , n ^E5 and n ^E6 are average degrees of polymerization, and n ^E1 is a number from 2 to 10. , n ^E2 is a number from 0 to 3, and n ^E3 is a number from 3 to 30. However, n ^E5 +n ^E6 = a number from 2 to 300 for n E4 =1, ^and n ^E6 ≧20 for n ^E5 =1. In general formula (E-2) above, n ^E7 is an integer of 1 or 2.
In general formulas (E-1) to (E-3) above, R ^E1 , R ^E2 and R ^E3 each independently represent a divalent diamine obtained by removing two amino groups from an aromatic diamine compound or an aliphatic diamine compound. and R ^E4 is a divalent group obtained by removing two carboxy groups from an aromatic dicarboxylic acid compound, an aliphatic dicarboxylic acid compound, or an oligomer having carboxy groups at both ends.
In the present specification, the term "aromatic dicarboxylic acid compound" means a compound having two carboxyl groups directly bonded to an aromatic hydrocarbon, and the term "aliphatic dicarboxylic acid compound" means an aliphatic hydrocarbon. means a compound having two carboxyl groups directly bonded to

The modified polyamide resin includes, for example, a diamine compound that is an aromatic diamine compound or an aliphatic diamine compound, an aromatic dicarboxylic acid compound, an aliphatic dicarboxylic acid compound, or a dicarboxylic acid compound that is an oligomer having carboxy groups at both ends, and phenol and a polybutadiene having carboxyl groups at both ends are reacted with each other to polycondense the carboxyl groups and amino groups of each component. In addition, these raw material components may be used individually by 1 type, and may use 2 or more types together about each.

Examples of the aromatic diamine compounds include diaminobenzene, diaminotoluene, diaminophenol, diaminodimethylbenzene, diaminomesitylene, diaminonitrobenzene, diaminodiazobenzene, diaminonaphthalene, diaminobiphenyl, diaminodimethoxybiphenyl, diaminodiphenyl ether, diaminodimethyldiphenyl ether, Methylenebis (dimethylaniline), Methylenebis (methoxyaniline), Methylenebis (dimethoxyaniline), Methylenebis (ethylaniline), Methylenebis (diethylaniline), Methylenebis (ethoxyaniline), Methylenebis (diethoxyaniline), Isopropylidenedianiline, Diaminobenzophenone , diaminodimethylbenzophenone, diaminoanthraquinone, diaminodiphenylthioether, diaminodimethyldiphenylthioether, diaminodiphenylsulfone, diaminodiphenylsulfoxide, diaminofluorene and the like.
Examples of the aliphatic diamine compounds include methylenediamine, ethylenediamine, propanediamine, hydroxypropanediamine, butanediamine, heptanediamine, hexanediamine, diaminodiethylamine, diaminopropylamine, cyclopentanediamine, cyclohexanediamine, azapentanediamine, tri zaunde diamine and the like.

Examples of the aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, biphenyldicarboxylic acid, methylene dibenzoic acid, thiodibenzoic acid, carbonyl dibenzoic acid, sulfonylbenzoic acid, and naphthalenedicarboxylic acid. .
Examples of the aliphatic dicarboxylic acid compounds include oxalic acid, malonic acid, methylmalonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, malic acid, tartaric acid, (meth)acryloyloxysuccinic acid, di (Meth)acryloyloxysuccinic acid, (meth)acryloyloxymalic acid, (meth)acrylamidosuccinic acid, (meth)acrylamidomalic acid and the like.

Examples of the phenolic hydroxyl group-containing dicarboxylic acid compounds include hydroxyisophthalic acid, hydroxyphthalic acid, hydroxyterephthalic acid, dihydroxyisophthalic acid, and dihydroxyterephthalic acid.

The number average molecular weight (Mn) of the polyamide resin (E) is preferably 20,000 to 30,000, more preferably 22,000 to 29,000, from the viewpoint of solvent solubility and film thickness retention after lamination. , more preferably 24,000 to 28,000.
From the same viewpoint, the weight average molecular weight (Mw) of the polyamide resin (E) is preferably 100,000 to 140,000, more preferably 103,000 to 130,000, still more preferably 105,000 to 120,000. is.

A commercially available product may be used as the polyamide resin (E). Examples of commercially available polyamide resins (E) include polyamide resins “BPAM-01” and “BPAM-155” (both trade names) manufactured by Nippon Kayaku Co., Ltd., and the like.

[Content of polyamide resin (E)]
When the first thermosetting resin composition contains the polyamide resin (E), the content of the polyamide resin (E) in the first thermosetting resin composition is not particularly limited. It is preferably 1 to 30% by mass, more preferably 4 to 20% by mass, still more preferably 7 to 15% by mass, relative to the total amount (100% by mass) of the resin components in the curable resin composition.
When the content of the polyamide resin (E) in the first thermosetting resin composition is at least the above lower limit, the conductor adhesion tends to be better. Moreover, when the content of the polyamide resin (E) in the first thermosetting resin composition is equal to or less than the above upper limit, it tends to be easy to adjust the balance of various properties well.

(Curing accelerator (F))
From the viewpoint of curability, the first thermosetting resin composition preferably further contains a curing accelerator (F).
The curing accelerator (F) may be used alone or in combination of two or more.

Examples of the curing accelerator (F) include acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, tributylamine and dicyandiamide; methylimidazole, phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1 -Imidazole compounds such as cyanoethyl-2-phenylimidazolium trimellitate; isocyanate mask imidazole compounds such as addition reaction products of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; quaternary ammonium compounds; Dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy) organic peroxides such as hexane, t-butylperoxyisopropylmonocarbonate, α,α'-bis(t-butylperoxy)diisopropylbenzene; and carboxylates such as manganese, cobalt and zinc.
Among these, isocyanate masked imidazole compounds are preferred.

When the first thermosetting resin composition contains the curing accelerator (F), the content of the curing accelerator (F) in the first thermosetting resin composition is not particularly limited, but thermosetting It is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, still more preferably 0.4 to 1 part by mass with respect to 100 parts by mass of the resin (A).
When the content of the curing accelerator (F) in the first thermosetting resin composition is at least the above lower limit, curability tends to be better. Moreover, when the content of the curing accelerator (F) in the first thermosetting resin composition is equal to or less than the above upper limit, the storage stability tends to be better.

(organic solvent)
The first thermosetting resin composition may be a varnish-like resin composition containing an organic solvent from the viewpoint of ease of handling.
An organic solvent may be used individually by 1 type, and may use 2 or more types together.

Examples of organic solvents include alcohol solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ether solvents such as tetrahydrofuran; aromatic hydrocarbon solvents such as toluene, xylene and mesitylene; nitrogen atom-containing solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; sulfur atom-containing solvents such as dimethylsulfoxide; ester solvents such as γ-butyrolactone, etc. mentioned.
Among these, from the viewpoint of solubility, alcohol solvents, ketone solvents, nitrogen atom-containing solvents, and aromatic hydrocarbon solvents are preferred, ketone solvents are more preferred, and methyl ethyl ketone is even more preferred.

When the first thermosetting resin composition contains an organic solvent, the solid content concentration of the first thermosetting resin composition is not particularly limited, but from the viewpoint of coatability, preferably 40 to 90% by mass. , more preferably 50 to 80% by mass, more preferably 60 to 70% by mass.

(other ingredients)
If necessary, the first thermosetting resin composition further contains a resin material other than the above components, a flame retardant, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a pigment, a coloring agent, and a lubricant. and one or more optional components selected from the group consisting of additives other than these.
Each of the above optional components may be used alone or in combination of two or more.
The content of the above optional component in the first thermosetting resin composition is not particularly limited, and may be used as necessary within a range that does not impair the effects of the present embodiment.
The first thermosetting resin composition may be free of the above optional components depending on the desired performance. In addition, it is preferable that the first thermosetting resin composition and the first thermosetting resin layer do not contain a fiber base material.

(Method for producing the first thermosetting resin composition)
The first thermosetting resin composition can be produced by mixing the above components.
When mixing each component, each component may be dissolved or dispersed while stirring. Conditions such as the order of mixing raw materials, mixing temperature, and mixing time are not particularly limited, and may be arbitrarily set according to the type of raw materials.

<Second thermosetting resin layer>
The second thermosetting resin layer is a thermosetting resin layer containing a rubber component.
In the metal foil with resin of this embodiment, cracks in the resin layer and curling of the metal foil with resin are prevented by providing the second thermosetting resin layer between the metal foil and the first thermosetting resin layer. occurrence is suppressed.
As used herein, the term "rubber component" means a crosslinked elastomer or a crosslinkable elastomer. The rubber component contained in the second thermosetting resin layer may exist in a form reacted with other components.

In the metal foil with resin of this embodiment, the content of the inorganic filler in the second thermosetting resin layer is 0 to 20% by mass.
When the content of the inorganic filler in the second thermosetting resin layer is equal to or less than the above upper limit, cracks in the resin layer and curling of the resin-coated metal foil can be sufficiently suppressed.
From the same viewpoint as above, the content of the inorganic filler in the second thermosetting resin layer is not particularly limited, but is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and still more preferably It is 0 to 1% by mass.
Examples of the inorganic filler include the same inorganic filler (B) as described above.

The thickness of the second thermosetting resin layer is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 10 μm, from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil. It is 1 to 7 μm, more preferably 1.5 to 4 μm.

The second thermosetting resin layer is preferably a layer formed from a second thermosetting resin composition containing a thermosetting resin and a rubber component.
In the following description, the thermosetting resin contained in the second thermosetting resin composition is referred to as "thermosetting resin (a)", and the rubber component contained in the second thermosetting resin composition may be referred to as "rubber component (b)".

(Thermosetting resin (a))
Examples of thermosetting resins (a) include epoxy resins, phenol resins, maleimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, Examples include silicone resins, triazine resins, melamine resins, and the like. Among these, from the viewpoint of heat resistance, maleimide resins, epoxy resins and cyanate resins are preferred, maleimide resins and epoxy resins are more preferred, and epoxy resins are even more preferred.
The thermosetting resin (a) may be used alone or in combination of two or more.

The epoxy resin used as the thermosetting resin (a) is preferably an epoxy resin having two or more epoxy groups. Epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, and the like. Among these, glycidyl ether type epoxy resins are preferred.

When the thermosetting resin (a) contains an epoxy resin, the content of the epoxy resin in the thermosetting resin (a) is not particularly limited, but is preferably 80 to 100% by mass, more preferably 90 to 100%. % by mass, more preferably 95 to 100% by mass.
When the content of the epoxy resin in the thermosetting resin (a) is within the above range, heat resistance and moldability tend to be better.

[Content of thermosetting resin (a)]
The content of the thermosetting resin (a) in the second thermosetting resin composition is not particularly limited, but the total amount of resin components in the second thermosetting resin composition (100% by mass) , preferably 30 to 80% by mass, more preferably 40 to 75% by mass, still more preferably 50 to 70% by mass.
When the content of the thermosetting resin (a) in the second thermosetting resin composition is at least the above lower limit, heat resistance and moldability tend to be better. Moreover, when the content of the thermosetting resin (a) in the second thermosetting resin composition is equal to or less than the above upper limit, it tends to be easy to adjust the balance of various properties well.

The total content of the resin components in the second thermosetting resin composition is not particularly limited, but from the viewpoint of heat resistance, the total solid content (100% by mass) of the second thermosetting resin composition , preferably 90 to 100% by mass, more preferably 95 to 100% by mass, still more preferably 99 to 100% by mass.
When the content of the resin component in the second thermosetting resin composition is within the above range, heat resistance and moldability tend to be better.
In addition, in the second thermosetting resin composition, the thermosetting resin (a) and the rubber component (b) correspond to the resin component. Optional components corresponding to the resin component include a curing agent (c), a thermoplastic resin (d), a curing accelerator (e), and the like, which will be described later.

(Rubber component (b))
Examples of the rubber component (b) include crosslinked rubber particles and liquid rubber. Among these, crosslinked rubber particles are preferable from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil.
Examples of crosslinked rubber particles include butadiene rubber particles, isoprene rubber particles, chloroprene rubber particles, styrene rubber particles, acrylic rubber particles, silicone rubber particles, natural rubber particles, styrene-butadiene rubber particles, acrylonitrile-butadiene rubber particles, and carboxylic acid-modified rubber particles. Examples include acrylonitrile-butadiene rubber particles and core-shell type rubber particles. Among these, acrylonitrile-butadiene rubber particles and carboxylic acid-modified acrylonitrile-butadiene rubber particles are preferred, and carboxylic acid-modified acrylonitrile-butadiene rubber particles are more preferred.
The rubber component (b) may be used alone or in combination of two or more.

Acrylonitrile-butadiene rubber particles are particles obtained by partially cross-linking acrylonitrile and butadiene during copolymerization. Moreover, carboxylic acid-modified acrylonitrile-butadiene rubber particles can be obtained by copolymerizing carboxylic acids such as acrylic acid and methacrylic acid together.

The average primary particle diameter (D ₅₀ ) of the crosslinked rubber particles is not particularly limited, but is preferably 50 to 1,000 nm from the viewpoint of more easily suppressing cracks in the resin layer and curling of the resin-coated metal foil.
The average primary particle size (D ₅₀ ) of the crosslinked rubber particles can be obtained by measuring with a laser diffraction particle size distribution meter.

[Content of rubber component (b)]
The content of the rubber component (b) in the second thermosetting resin composition is not particularly limited. It is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 3 to 7% by mass.
When the content of the rubber component (b) in the second thermosetting resin composition is at least the above lower limit, cracks in the resin layer and curling of the resin-coated metal foil tend to be more easily suppressed. Moreover, when the content of the rubber component (b) in the second thermosetting resin composition is equal to or less than the above upper limit, the heat resistance tends to be better.

(Curing agent (c))
The second thermosetting resin composition may further contain a curing agent (c). In particular, when an epoxy resin is contained as the thermosetting resin (a), it is preferable to contain an epoxy resin curing agent as the curing agent (c).
The curing agent (c) may be used alone or in combination of two or more.

Examples of epoxy resin curing agents include amine curing agents, phenolic resin curing agents, acid anhydride curing agents, and the like. Among these, phenolic resin curing agents are preferred.
As the phenolic resin-based curing agent, a novolak-type phenolic resin is preferred.
The novolak-type phenolic resin may be a phenol having no substituents other than hydroxyl groups that has been novolacified, or a phenol having substituents other than hydroxyl groups such as cresol and the like that has been novolakified.

Moreover, the novolac-type phenolic resin may be a triazine ring-containing novolak-type phenolic resin containing a triazine ring in the main chain.
The nitrogen content in the triazine ring-containing novolac-type phenolic resin is not particularly limited, but from the viewpoint of dielectric properties and solvent solubility, it is preferably 10 to 25% by mass, more preferably 11 to 22% by mass, and still more preferably 12% by mass. ~19% by mass.

The phenolic hydroxyl group equivalent of the phenolic resin-based curing agent is not particularly limited, but is preferably 100 to 300 g/mol, more preferably 120 to 200 g/mol, and still more preferably 140 to 170 g/mol.

[Content of curing agent (c)]
When the second thermosetting resin composition contains the curing agent (c), the content of the curing agent (c) in the second thermosetting resin composition is not particularly limited, but the thermosetting resin (a) is preferably 5 to 100 parts by mass, more preferably 10 to 70 parts by mass, and still more preferably 20 to 40 parts by mass based on 100 parts by mass.
When the content of the curing agent (c) in the second thermosetting resin composition is within the above range, the heat resistance tends to be better.

(Thermoplastic resin (d))
The second thermosetting resin composition preferably further contains a thermoplastic resin (d).
The thermoplastic resin (d) may be used alone or in combination of two or more.

Examples of thermoplastic resins (d) include polyethylene resins, polypropylene resins, polybutadiene resins, polystyrene resins, polyphenylene ether resins, polycarbonate resins, polyester resins, polyamide resins, polyvinyl acetal resins, and copolymerization of monomers constituting these resins. A coalescence etc. are mentioned. Among these, polyvinyl acetal resin is preferable.
The polyvinyl acetal resin may be a polyvinyl acetal resin having a carboxy group modified with a carboxylic acid.
The polymerization degree of the polyvinyl acetal resin is preferably 1,000 to 2,500 from the viewpoint of heat resistance. The degree of polymerization of polyvinyl acetal resin can be calculated from the number average molecular weight (Mn) of polyvinyl acetate as a raw material.

[Content of thermoplastic resin (d)]
When the second thermosetting resin composition contains the thermoplastic resin (d), the content of the thermoplastic resin (d) in the second thermosetting resin composition is not particularly limited. It is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and still more preferably 7 to 15% by mass relative to the total amount (100% by mass) of the resin components in the thermosetting resin composition.
When the content of the thermoplastic resin (d) in the second thermosetting resin composition is at least the above lower limit, cracks in the resin layer and curling of the resin-coated metal foil tend to be more easily suppressed. Moreover, when the content of the thermoplastic resin (d) in the second thermosetting resin composition is equal to or less than the above upper limit, it tends to be easy to adjust the balance of various properties well.

(Curing accelerator (e))
The second thermosetting resin composition preferably further contains a curing accelerator (e).
The curing accelerator (e) may be used alone or in combination of two or more.

Examples of the curing accelerator (e) include acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, tributylamine and dicyandiamide; methylimidazole, phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1 -Imidazole compounds such as cyanoethyl-2-phenylimidazolium trimellitate; isocyanate mask imidazole compounds such as addition reaction products of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; quaternary ammonium compounds; Dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(t-butylperoxy) organic peroxides such as hexane, t-butylperoxyisopropylmonocarbonate, α,α'-bis(t-butylperoxy)diisopropylbenzene; and carboxylates such as manganese, cobalt and zinc. Among these, imidazole compounds are preferred, and 1-cyanoethyl-2-phenylimidazolium trimellitate is more preferred.

When the second thermosetting resin composition contains the curing accelerator (e), the content of the curing accelerator (e) in the second thermosetting resin composition is not particularly limited. It is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, still more preferably 0.3 to 1 part by mass, based on 100 parts by mass of the flexible resin (a).
When the content of the curing accelerator (e) in the second thermosetting resin composition is at least the above lower limit, curability tends to be better. Moreover, when the content of the curing accelerator (e) in the second thermosetting resin composition is equal to or less than the above upper limit, the storage stability tends to be better.

(organic solvent)
The second thermosetting resin composition may be a varnish-like resin composition containing an organic solvent from the viewpoint of ease of handling.
An organic solvent may be used individually by 1 type, and may use 2 or more types together.
Examples of the organic solvent include the same organic solvent as the organic solvent that may be contained in the first thermosetting resin composition, and preferred aspects of the type and amount used are also the same.

(other ingredients)
If necessary, the second thermosetting resin composition further contains a resin material other than the above components, a flame retardant, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a pigment, a coloring agent, and a lubricant. and one or more optional components selected from the group consisting of additives other than these.
Each of the above optional components may be used alone or in combination of two or more.
The content of the above-described optional components in the second thermosetting resin composition is not particularly limited, and may be used as necessary within a range that does not impair the effects of the present embodiment.
The second thermosetting resin composition may be free of the above optional components depending on the desired performance. In addition, it is preferable that the second thermosetting resin composition and the second thermosetting resin layer do not contain a fiber base material.

(Method for producing second thermosetting resin composition)
The second thermosetting resin composition can be produced by mixing the above components.
When mixing each component, each component may be dissolved or dispersed while stirring. Conditions such as the order of mixing raw materials, mixing temperature, and mixing time are not particularly limited, and may be arbitrarily set according to the type of raw materials.

<Elastic modulus of resin layer>
In the resin-coated metal foil of the present embodiment, the cured product of the second thermosetting resin layer has a storage elastic modulus E′ at 25° C. (hereinafter also referred to as “25° C. storage elastic modulus E′(i)”), Although not particularly limited, it is preferably 1.2 to 4.0 GPa, more preferably 1.5 to 3.5 GPa, still more preferably 1.5 to 3.5 GPa, from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil. 2.0 to 3.0 GPa.
In the resin-coated metal foil of the present embodiment, the cured product of the second thermosetting resin layer has a storage elastic modulus E′ at 150° C. (hereinafter also referred to as “150° C. storage elastic modulus E′(i)”) of Although it is not particularly limited, it is preferably 0.1 to 1.0 GPa, more preferably 0.3 to 0.8 GPa, and still more preferably from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil. 0.4 to 0.6 GPa.
The 25°C storage modulus E'(i) and the 150°C storage modulus E'(i) can be measured by the method described in Examples.

In the resin-coated metal foil of the present embodiment, the cured product of the resin layer composed of the second thermosetting resin layer and the first thermosetting resin layer has a storage elastic modulus E' at 25 ° C. (hereinafter referred to as "25 ° C. storage The elastic modulus E′(ii)”) is not particularly limited, but from the viewpoint of forming an insulating layer having an appropriate mechanical strength, it is preferably 4.0 to 9.0 GPa, more preferably 5.0 to 8.0 GPa, more preferably 6.0 to 7.0 GPa.
In the resin-coated metal foil of the present embodiment, the cured product of the resin layer composed of the second thermosetting resin layer and the first thermosetting resin layer has a storage elastic modulus E' at 150 ° C. (hereinafter referred to as "150 ° C. storage Elastic modulus E′(ii)”) is not particularly limited, but is preferably 2.0 to 7.0 GPa, more preferably 3.0 to 7.0 GPa, from the viewpoint of forming an insulating layer having appropriate mechanical strength. 6.0 GPa, more preferably 4.0 to 5.0 GPa.
The 25°C storage modulus E'(ii) and the 150°C storage modulus E'(ii) can be measured by the method described in Examples.

The difference between the 25° C. storage modulus E′(ii) and the 25° C. storage modulus E′(i) [25° C. storage modulus E′(ii)−25° C. storage modulus E′(i)] is particularly Although not limited, it is preferably 2.0 to 7.0 GPa, more preferably 3.0 to 6.0 GPa, still more preferably 4 from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil. .0 to 5.0 GPa.
The difference between the 150° C. storage modulus E′(ii) and the 150° C. storage modulus E′(i) [150° C. storage modulus E′(ii)−150° C. storage modulus E′(i)] is particularly Although not limited, it is preferably 2.0 to 7.0 GPa, more preferably 3.0 to 6.0 GPa, still more preferably 4 from the viewpoint of making it easier to suppress cracks in the resin layer and curling of the resin-coated metal foil. .0 to 5.0 GPa.

<Metal foil>
Examples of metal foil include copper foil, tin foil, tin-lead alloy foil, and nickel foil. Among these, copper foil is preferable. The copper foil preferably has a copper content of 95% by mass or more.
The metal foil conforms to JIS standards (electrolytic copper foil for printed wiring boards: JIS C6512, rolled copper foil for printed wiring boards: JIS C6513) or IPC standards (IPC 4562

standards Grades

1, 2, and 3). , is preferable from the viewpoint of use in semiconductor packages.

The surface of the metal foil on which the resin layer is to be formed may be roughened from the viewpoint of adhesion.
The roughening treatment can be applied by forming roughening particles on the surface of the metal foil.
As roughening particles, for example, electrodeposited particles made of a single substance selected from copper, nickel, phosphorus, tungsten, arsenic, molybdenum, chromium, cobalt and zinc, or alloys containing one or more of these Electrodeposited grains are preferred.
The roughening particles may be used singly or in combination of two or more.

In addition to the above roughening treatment, the metal foil is subjected to, for example, a single substance selected from nickel, cobalt, copper and zinc, an alloy containing one or more of these, and the like to remove secondary particles, tertiary particles, and A rust layer, a heat-resistant layer, or the like may be formed.
In addition to the layers described above, the surface may be subjected to surface treatment such as chromate treatment or silane coupling treatment.

The thickness of the metal foil is not particularly limited and may be appropriately adjusted depending on the application of the metal foil with resin, but is preferably 0.1 to 35 μm, more preferably 0.3 to 15 μm, and still more preferably 0.1 μm. 5 to 5 μm.
When the thickness of the metal foil is equal to or greater than the above lower limit, the handleability of the resin-coated metal foil tends to be further improved. On the other hand, if the thickness of the metal foil is equal to or greater than the above lower limit, it tends to be more suitable for increasing the wiring density.
Note that the thickness of the metal foil described above does not include the thickness of the carrier foil, which will be described later.

A carrier foil may be provided on the metal foil. The carrier foil corresponds to a support that is provided as necessary in order to improve handleability when the thickness of the metal foil is thin. Therefore, the carrier foil is removed during the manufacturing process of the printed wiring board.
Examples of carrier foil include copper foil, aluminum foil, and nickel foil. Among these, copper foil is preferable.

The thickness of the carrier foil is preferably 5 to 50 μm, more preferably 7 to 35 μm, still more preferably 10 to 25 μm, from the viewpoints of improving the handleability of the resin-coated metal foil and from the viewpoint of production cost.
When the thickness of the carrier foil is at least the above lower limit, the handleability of the resin-coated metal foil tends to be further improved. On the other hand, when the thickness of the carrier foil is equal to or less than the above upper limit, there is a tendency that the cost of the resin-coated metal foil can be further reduced.

A release layer may be provided between the metal foil and the carrier foil. A peeling layer is a layer provided between the metal foil and the carrier foil as necessary in order to facilitate the peeling of the carrier foil from the metal foil.
Exfoliation layers include, for example, layers containing one or more metals selected from chromium, nickel, cobalt, iron, molybdenum, titanium, tungsten, phosphorus, copper, and aluminum. These metals may be alloys, hydrates, oxides, and the like. The release layer may be one layer or multiple layers.
The peeling layer is, for example, electroplating, electroless plating, wet plating such as immersion plating; sputtering, chemical vapor deposition (CVD; Chemical Vapor Deposition), physical vapor deposition (PDV; Physical Vapor Deposition), etc. can be formed by

<Method for manufacturing resin-coated metal foil>
The method for producing the resin-coated metal foil of the present embodiment is not particularly limited. For example, a second thermosetting resin layer is formed on the metal foil, and then the first thermosetting resin layer is formed on the second thermosetting resin layer. and a method of forming a thermosetting resin layer.

As a method of forming the second thermosetting resin layer on the metal foil, a method of applying the second varnish-like thermosetting resin composition on the metal foil and then drying is preferable.
The drying temperature of the applied second thermosetting resin composition is not particularly limited, but from the viewpoint of productivity and moderate B-stage of the second thermosetting resin composition, it is preferably 160 to 210 ° C. , more preferably 170 to 200°C, more preferably 180 to 190°C.
The drying time of the applied second thermosetting resin composition is not particularly limited, but from the viewpoint of productivity and moderate B-stage of the second thermosetting resin composition, preferably 1 to 10 minutes. , more preferably 1 to 7 minutes, more preferably 1 to 4 minutes.

As a method for forming the first thermosetting resin layer on the second thermosetting resin layer, a varnish-like first thermosetting resin composition was applied on the second thermosetting resin layer. A drying method is preferred.
The drying temperature of the applied first thermosetting resin composition is not particularly limited, but from the viewpoint of productivity and moderate B-stage of the first thermosetting resin composition, it is preferably 90 to 170 ° C. , more preferably 100 to 160°C, more preferably 110 to 150°C.
The drying time of the applied first thermosetting resin composition is not particularly limited, but from the viewpoint of productivity and moderate B-stage of the second thermosetting resin composition, preferably 1 to 15 minutes. , more preferably 1 to 10 minutes, more preferably 2 to 6 minutes.

Examples of coating devices for coating the first and second thermosetting resin compositions include coating devices known to those skilled in the art such as comma coaters, bar coaters, kiss coaters, roll coaters, gravure coaters, and die coaters. can be used. These coating apparatuses may be appropriately selected according to the film thickness to be formed.

[Printed wiring board and its manufacturing method]
The printed wiring board of the present embodiment is a printed wiring board formed using the resin-coated metal foil of the present embodiment, comprising: a circuit board having a circuit on at least one surface; The printed wiring board includes a laminated structure having a cured product layer of the thermosetting resin layer and a cured product layer of the second thermosetting resin layer in this order.

The printed wiring board of the present embodiment can be manufactured by a method of embedding the circuit of a circuit board having a circuit on at least one surface with the first thermosetting resin layer of the resin-coated metal foil.

Examples of circuit boards include glass epoxy, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, thermosetting polyphenylene ether substrates, and the like, on which a patterned circuit is formed on one or both sides.
From the viewpoint of adhesiveness, the surface of the circuit may be roughened in advance by blackening treatment or the like.

The resin-coated metal foil is placed on the circuit board so that the first thermosetting resin layer is in contact with the circuit, and is molded under heat and pressure so that the first thermosetting resin layer mainly melts and melts. A cured material layer is formed that cures to embed the circuit. The cured material layer functions as an insulating layer for circuits.
For heat-press molding, for example, a multi-stage press, a multi-stage vacuum press, continuous molding, an autoclave molding machine, etc. can be used.
The heating temperature for hot-press molding is not particularly limited, but is preferably 100 to 300.degree. C., more preferably 150 to 280.degree. C., still more preferably 200 to 250.degree.
The heating and pressing time for the heating and pressing molding is not particularly limited, but is preferably 10 to 300 minutes, more preferably 30 to 200 minutes, still more preferably 80 to 150 minutes.
The pressure for hot-press molding is not particularly limited, but is preferably 1.5 to 5 MPa, more preferably 1.7 to 3 MPa, still more preferably 1.8 to 2.5 MPa.
However, these conditions can be appropriately adjusted according to the type of raw material used, etc., and are not particularly limited.

By the above method, a laminate is formed in which the circuit board, the cured layer of the first thermosetting resin layer in which the circuit is embedded, the cured layer of the second thermosetting resin layer, and the metal foil are laminated in this order. be done.
The metal foil of the outermost layer may be removed by etching, or may be used as it is to form the circuit.

After forming the cured material layer, holes may be drilled as necessary. Drilling is a step of drilling holes in the circuit board and the formed cured material layer by a method such as a drill, laser, plasma, or a combination thereof to form via holes, through holes, and the like. Examples of lasers used for drilling include carbon dioxide lasers, YAG lasers, UV lasers, excimer lasers, and the like.

When removing the metal foil derived from the resin-coated metal foil by etching, the exposed hardened layer of the second thermosetting resin layer may be roughened with an oxidizing agent. The roughening treatment can form uneven anchors on the surface of the cured material layer.
Examples of the oxidizing agent include permanganates such as potassium permanganate and sodium permanganate, bichromate, ozone, hydrogen peroxide, sulfuric acid, and nitric acid. Among these, potassium permanganate and sodium permanganate are preferable from the viewpoint of versatility.

When the outermost layer is a metal foil, a circuit may be formed on the metal foil, or the metal foil itself may be patterned to form a circuit, depending on the form of the metal foil.
Further, when the outermost layer is a cured layer of the second thermosetting resin layer, a circuit may be formed on the cured layer after the above roughening treatment, if necessary. good.

When providing a conductor for forming a circuit, the conductor is preferably formed by a plating method such as an electroless plating method or an electrolytic plating method. 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 preferable, and copper is more preferable.

For conductor pattern processing, use known methods such as the subtractive method, full additive method, semi-additive method (SAP: SemiAdditive Process), modified semi-additive process (m-SAP: modified Semi Additive Process), etc. can be done.

[Semiconductor package]
The semiconductor package of this embodiment is a semiconductor package formed using the printed wiring board of this embodiment.
The semiconductor package of this embodiment can be manufactured, for example, by mounting a semiconductor chip, a memory, etc. on the printed wiring board of this embodiment by a known method.

The present embodiment will be specifically described below with reference to Examples. However, this embodiment is not limited to the following examples.

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

Production example 1
(Synthesis of silicone-modified maleimide resin)
Polydimethylsiloxane having primary amino groups at both ends (Shin-Etsu Chemical Co., Ltd., product Name "KF-8012", primary amino group equivalent weight 400 g / mol) 172.0 parts by mass, bis (4-maleimidophenyl) methane 75.1 parts by mass, p-aminophenol 2.8 parts by mass, 250 parts by mass of propylene glycol monomethyl ether was added and reacted at 115° C. for 6 hours to obtain a silicone-modified maleimide resin.

[Manufacturing of resin-coated metal foil]
Examples 1-8
(Preparation of first thermosetting resin composition)
69.5 parts by mass of the silicone-modified maleimide resin obtained in Production Example 1, and 10 parts of a biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name "NC-3000-H", epoxy group equivalent: 290 g/mol). .0 parts by mass, 5.0 parts by mass of 3,3'-diethyl-4,4'-diaminodiphenylmethane, carboxylic acid-modified hydrogenated styrene-butadiene copolymer resin (manufactured by Asahi Kasei Chemicals Co., Ltd., trade name "Tuftec (registered Trademark) M1913", molar ratio of structural units derived from styrene and structural units derived from butadiene (styrene:butadiene) = 30:70, acid value 10 _mgCH3ONa /g), 5.0 parts by mass, polyamide resin (Nippon Kagaku Pharmaceutical Co., Ltd., trade name "BPAM-155", number average molecular weight (Mn): 26,000, weight average molecular weight (Mw): 110,000) 10.0 parts by mass, isocyanate mask imidazole (Daiichi Kogyo Seiyaku Co., Ltd., trade name “G-8009L”), 200.0 parts by mass of fused spherical silica (average particle size (D ₅₀ ) 0.5 μm), methyl ethyl ketone, and solid content concentration A first thermosetting resin composition having a content of 65% by mass was obtained.

(Preparation of second thermosetting resin composition)
65.0 parts by mass of biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name “NC-3000S-H”, epoxy group equivalent 285 g / mol), carboxylic acid-modified acrylonitrile butadiene rubber particles (manufactured by JSR Corporation, 5 parts by mass of carboxylic acid-modified polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd., product name "KS-23Z"), 10.0 parts by mass of cresol novolac-type phenolic resin ( DIC Corporation, trade name “Phenolite (registered trademark) EXB-9829, hydroxyl equivalent 151 g / mol) 20.0 parts by mass, 1-cyanoethyl-2-phenylimidazolium trimellitate 0.3 parts by mass , and methyl ethyl ketone to obtain a second thermosetting resin composition having a solid concentration of 70% by mass.

(Manufacture of resin-coated metal foil)
On a copper foil with a carrier (manufactured by Mitsui Mining & Smelting Co., Ltd., trade name "MT18SP2-1.5", the thickness of the carrier foil is 18 μm, the thickness of the copper foil excluding the carrier foil is 1.5 μm), After applying the second thermosetting resin composition obtained above so that the thickness of the second thermosetting resin layer after drying becomes the thickness shown in Table 1, After drying under the conditions, a second thermosetting resin layer was formed on the copper foil.
Then, the first thermosetting resin composition is applied on the second thermosetting resin layer formed above, and the thickness of the first thermosetting resin layer after drying is shown in Table 1. After being coated so as to obtain a resin-coated metal foil having a first thermosetting resin layer, a second thermosetting resin layer and a copper foil in this order, the resin-coated metal foil was dried under the conditions shown in Table 1.

Comparative example 1
The first thermosetting resin composition obtained in the same manner as in Example 1 was placed on the same copper foil as that used in Example 1, and the thickness of the first thermosetting resin layer after drying was shown. 1 and then dried under the conditions shown in Table 1 to obtain a resin-coated metal foil having a first thermosetting resin layer on a copper foil.

[Evaluation method]
Using the resin composition and resin-coated metal foil obtained in each example, each evaluation was performed according to the following methods.

(Method for measuring storage elastic modulus E' of resin layer)
A resin film having a thickness of 200 μm was formed from the second thermosetting resin composition obtained in Example 1, and copper foil was placed on both sides of the film. The resin film was cured by pressing for 60 minutes at a holding temperature of 180°C. The obtained laminate having copper foils on both sides was immersed in a copper etchant to remove the copper foils on both sides, and a 5 mm×40 mm piece was cut out to obtain a test piece. Using the test piece as a measurement object, using a dynamic viscoelasticity measuring device (manufactured by UBM Co., Ltd., trade name "Rheogel-E4000"), the measurement temperature range is 25 to 320 ° C., the temperature increase rate is 5 ° C./min, and the frequency is 10 Hz. The storage modulus E' was measured under the conditions of
As a result, the 25° C. storage elastic modulus E′(i) of the cured product of the second thermosetting resin layer alone was 2.4 GPa, and the 150° C. storage elastic modulus E′(i) was 0.5 GPa. .

Next, two metal foils with resin obtained in Example 4 were prepared and placed so that the first thermosetting resin layers faced each other. Then, using a molding press, this was pressed for 90 minutes under conditions of a pressure of 2.0 MPa and a maximum holding temperature of 230° C. to cure each resin layer. The obtained laminate having copper foils on both sides is immersed in a copper etching solution to remove the copper foils on both sides, and a test piece cut into 5 mm × 40 mm is used as a test piece, and the storage elastic modulus E is measured under the same conditions as above. ' was measured.
As a result, the 25° C. storage elastic modulus E′(ii) of the cured product of the resin layer composed of the second thermosetting resin layer and the first thermosetting resin layer was 6.8 GPa, and the 150° C. storage elastic modulus was 6.8 GPa. The modulus E'(ii) was 4.7 GPa. That is, the difference between the 25° C. storage modulus E′(ii) and the 25° C. storage modulus E′(i) [25° C. storage modulus E′(ii)−25° C. storage modulus E′(i)] is , 4.4 GPa, and the difference between the 150° C. storage modulus E′(ii) and the 150° C. storage modulus E′(i) [150° C. storage modulus E′(ii)−150° C. storage modulus E′ (i)] was 4.2 GPa.

(Method for evaluating cracks in resin layer)
On the surface of the first thermosetting resin layer of the resin-coated metal foil obtained in each example, an arbitrarily selected range of 335 mm × 300 mm was observed with a fluorescence microscope to determine the presence or absence of cracks in the resin layer. confirmed. In Table 1, "A" indicates that cracks were not observed in the resin layer, and "C" indicates that cracks were observed in the resin layer.

(Method for measuring curl size)
The metal foil with resin obtained in each example was cut into a size of 335 mm×300 mm, and the maximum height when the metal foil was placed on a flat surface with the metal foil facing downward was taken as the curl value (mm).

(Method for evaluating moisture absorption and heat resistance)
The resin-coated metal foil obtained in each example was placed on both sides of a circuit board having circuits on both sides so that the first thermosetting resin layer was on the circuit side. Next, using a molding press, this is pressed for 90 minutes under conditions of a pressure of 2.0 MPa and a maximum holding temperature of 230° C., and the resin layers are cured while embedding the circuit with the first thermosetting resin composition. let me The obtained laminate having copper foils on both sides was cut into a size of 50 mm square, and only half of one surface was left with copper, and the other surface was immersed in a copper etching solution to remove the copper from the entire surface. An evaluation board was produced.
The half-copper-attached evaluation board was treated in a pressure cooker test apparatus (manufactured by Hirayama Seisakusho Co., Ltd.) under conditions of 121° C. and 2.2 atm for 1 to 5 hours. After immersing the evaluation board with semi-copper after treatment in a solder bath at 288° C. for 20 seconds, the appearance was visually observed to confirm the presence or absence of swelling. In each example and each processing time, three evaluation substrates were evaluated. In Table 1, "A" indicates that no swelling was observed in any of the three, "B" indicates that one swelling was observed, "C" indicates that two swellings were observed, and three swellings were observed. Those observed were labeled as "D".

As can be seen from Table 1, no cracks were observed in the resin layers of the resin-coated metal foils obtained in Examples 1 to 8 of the present embodiment, and curling of the resin-coated metal foils was suppressed. In addition, these resin-coated metal foils were also excellent in moisture absorption and heat resistance.
On the other hand, in the resin-coated metal foil obtained in Comparative Example 1, in which the second thermosetting resin layer was not formed, cracks were observed in the resin layer, and the resin-coated metal foil was greatly curled. In addition, the resin-coated metal foil of Comparative Example 1 was also inferior in moisture absorption and heat resistance.

Since the resin-coated metal foil of the present embodiment suppresses cracking of the resin layer and curling of the resin-coated metal foil, it is suitable for electronic component applications such as prepregs, laminates, printed wiring boards, and semiconductor packages. .

1 metal foil with resin 2 metal foil 3 second thermosetting resin layer 4 first thermosetting resin layer

Claims

a first thermosetting resin layer containing an inorganic filler;
a second thermosetting resin layer containing a rubber component;
and a metal foil in this order,
The content of the inorganic filler in the first thermosetting resin layer is 50 to 90 mass%,
The content of the inorganic filler in the second thermosetting resin layer is 0 to 20% by mass,
Metal foil with resin.
The first thermosetting resin layer is a layer formed from a first thermosetting resin composition containing a thermosetting resin and an inorganic filler,
The thermosetting resin contained in the first thermosetting resin composition is at least one selected from the group consisting of maleimide resins having at least one N-substituted maleimide group and derivatives thereof. 2. The metal foil with resin according to 1.
one or more selected from the group consisting of maleimide resins having one or more N-substituted maleimide groups and derivatives thereof, a structure derived from a maleimide resin having two or more N-substituted maleimide groups, and a primary amino group; The resin-coated metal foil according to claim 2, which is a resin containing a structure derived from a silicone compound having
The second thermosetting resin layer is a layer formed from a second thermosetting resin composition containing a thermosetting resin and a rubber component,
4. The resin-coated metal foil according to claim 1, wherein the thermosetting resin contained in said second thermosetting resin composition is an epoxy resin.
The resin-coated metal foil according to claim 4, wherein the second thermosetting resin composition further contains a phenol resin-based curing agent.
The resin-coated metal foil according to any one of claims 1 to 3, wherein the rubber component is crosslinked rubber particles.
The resin-coated metal foil according to any one of claims 1 to 3, wherein the content of the inorganic filler in the second thermosetting resin layer is 0 to 5% by mass.
The resin-coated metal foil according to any one of claims 1 to 3, wherein the metal foil is a copper foil.
A printed wiring board formed using the resin-coated metal foil according to any one of claims 1 to 3,
a circuit board having a circuit on at least one side;
a cured material layer of the first thermosetting resin layer in which the circuit is embedded;
A cured product layer of the second thermosetting resin layer;
A printed wiring board, comprising a laminate structure having in that order:
A semiconductor package formed using the printed wiring board according to claim 9.
A method for manufacturing a printed wiring board according to claim 9,
A method of manufacturing a printed wiring board, wherein the circuit of the circuit board having the circuit on at least one surface is embedded with the first thermosetting resin layer of the metal foil with resin.