Resin composition, prepreg, resin-attached film, resin-attached metal foil, metal-clad laminate, and wiring board

Abstract

The present disclosure addresses the problem of providing a resin composition that realizes excellent circuit filling properties, dielectric loss tangent, water absorption, and laser processability. This resin composition comprises: a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond; a maleimide compound (B) having a functional group equivalent of 230-500 g / eq.; a free radical compound (C) that has a molecular weight of 160-800 and that has at least one selected from the group consisting of groups represented by formula (1), formula (2), formula (3), and formula (4); and an inorganic filler (D). The resin composition does not contain a phenol compound, or the resin composition contains a phenol compound and the percentage content of the phenol compound is not more than 0.01 mass% with respect to the total amount of solid content of the resin composition.

Description

Resin composition, prepreg, resin film, metal foil with resin, metal-clad laminate, and wiring board

[0001] The present disclosure generally relates to a resin composition, a prepreg, a resin film, a metal foil with resin, a metal-clad laminate, and a wiring board, and more particularly to a resin composition containing a polyphenylene ether compound, a prepreg containing the resin composition, a resin film, a metal foil with resin, a metal-clad laminate, and a wiring board.

[0002] Patent Document 1 discloses a resin composition. This resin composition contains a polyphenylene ether resin having an unsaturated bond, a maleimide resin represented by the formula (10), and a compound represented by the formula (11) or the formula (12).

[0003]

[0004]

[0005]

[0006] In the formula (10), R １ represents a covalent bond, -CH ２ -, -CH(CH ３ ) -, -C(CH ３ ) ２ -, -O -, -S -, -SO ２ -, or a carbonyl group, and R ２ to R ５ each independently represents a hydrogen atom or an alkyl group of C １ to C ５ and R ２ to R ５ do not simultaneously represent hydrogen atoms.

[0007] In the formula (11), X １ represents an oxygen radical or a hydroxy group, and R ６ to R ９ each independently represents a hydrogen atom or an alkyl group of C １ to C ５ and R ２ to R ５ do not simultaneously represent hydrogen atoms, and R １０This represents a hydrogen atom, a methyl group, an amino group, a hydroxyl group, a carbonyl group, or a carboxyl group.

[0008] In formula (12), X ２ R represents an oxygen radical or a hydroxyl group. １１ ~R １４ Each of these is independently a hydrogen atom or C １ ~C ５ The alkyl group is R １１ ~R １４ It does not simultaneously show a hydrogen atom, R １５ and R １６ Each of these independently represents a hydrogen atom, a methyl group, an amino group, a hydroxyl group, a carbonyl group, or a carboxyl group, or R １５ and R １６ Together, they form a benzene ring structure.

[0009] However, the resin composition described in Patent Document 1 had the problem of poor dielectric loss tangent and water absorption. Furthermore, the laser processability of this resin composition was unknown.

[0010] U.S. Patent Application Publication No. 2021 / 032463

[0011] The object of this disclosure is to provide resin compositions, prepregs, resin-coated films, resin-coated metal foils, metal-clad laminates, and wiring boards that achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0012] A resin composition according to one aspect of the present disclosure is a resin composition containing a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond, a maleimide compound (B) having a functional group equivalent of 230 g / eq. to 500 g / eq., a free radical compound (C) having a molecular weight of 160 to 800 and having at least one selected from the group consisting of groups represented by formulas (1), (2), (3), and (4), and an inorganic filler (D). The resin composition does not contain a phenol compound, or the resin composition contains a phenol compound, and the content of the phenol compound is 0.01% by mass or less with respect to the total amount of solids in the resin composition.

[0013]

[0014]

[0015]

[0016]

[0017] A prepreg according to one aspect of the present disclosure comprises the resin composition or a semi-cured product of the resin composition and a fibrous substrate.

[0018] A resin-coated film according to one aspect of the present disclosure comprises a resin layer containing the resin composition or a semi-cured product of the resin composition, and a support film.

[0019] A resin-coated metal foil according to one aspect of the present disclosure comprises a resin layer containing the resin composition or a semi-cured product of the resin composition, and a metal foil.

[0020] A metal-clad laminate according to one aspect of the present disclosure comprises an insulating layer containing a cured product of the resin composition and a metal foil.

[0021] A metal-clad laminate according to one aspect of the present disclosure comprises an insulating layer containing a cured prepreg and a metal foil.

[0022] A wiring board according to one aspect of the present disclosure comprises an insulating layer containing a cured product of the resin composition and wiring.

[0023] A wiring board according to one aspect of the present disclosure comprises an insulating layer containing a cured prepreg and wiring.

[0024] Figure 1 is a schematic cross-sectional view of a prepreg according to one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view of a resin-coated film according to one embodiment of the present disclosure. Figure 3 is a schematic cross-sectional view of a resin-coated metal foil according to one embodiment of the present disclosure. Figure 4 is a schematic cross-sectional view of a metal-clad laminate according to one embodiment of the present disclosure. Figure 5 is a schematic cross-sectional view of a wiring board according to one embodiment of the present disclosure.

[0025] Embodiments of this disclosure will now be described. Note that the embodiments described below are only a selection of the various embodiments of this disclosure. Furthermore, the embodiments described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. In addition, while the mechanisms of operation in the embodiments may be described, these descriptions of mechanisms of operation include explanations based on speculation, and this disclosure is not bound by the descriptions of mechanisms of operation.

[0026] 1. Overview The resin composition according to this embodiment contains a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond, a maleimide compound (B) having a functional group equivalent of 230 g / eq. to 500 g / eq., a free radical compound (C) having a molecular weight of 160 to 800 and having at least one group selected from the group consisting of formulas (1), (2), (3), and (4), and an inorganic filler (D). The resin composition does not contain a phenol compound, or the resin composition contains a phenol compound, and the content of the phenol compound is 0.01% by mass or less with respect to the total amount of solids in the resin composition.

[0027]

[0028]

[0029]

[0030]

[0031] Because it possesses the above-described structure, the resin composition in this disclosure achieves excellent circuit filling properties, dielectric loss tangent, water absorption, and laser processability. Specifically, the resin composition contains a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond and a maleimide compound (B) having a functional group equivalent of 230 g / eq. to 500 g / eq., so both are highly reactive and can achieve good dielectric properties such as dielectric loss tangent and water absorption. Furthermore, because the resin composition contains a free radical compound (C), the reaction between the polyphenylene ether compound (A) and the maleimide compound (B) can be homogenized, thereby achieving good circuit filling properties and laser processability.

[0032] The prepreg, resin-coated sheet, and resin-coated metal foil according to this embodiment include the above-mentioned resin composition or a semi-cured product thereof. That is, since the resin layer of the prepreg, resin-coated sheet, and resin-coated metal foil is manufactured from the resin composition, it is possible to obtain a prepreg, resin-coated sheet, and resin-coated metal foil that achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0033] The metal-clad laminates and wiring boards according to this embodiment include a cured product of the resin composition or prepreg. That is, since the insulating layer of the metal-clad laminates and wiring boards is manufactured from the resin composition, it is possible to obtain metal-clad laminates and wiring boards that achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0034] 2. Details (1) Resin composition The resin composition according to this embodiment will be described below.

[0035] (1.1) Components <Polyphenylene ether compound> As described above, the resin composition contains a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond. The polyphenylene ether compound (A) is a component that can reduce the dielectric loss tangent and improve the heat resistance of the cured product of the resin composition.

[0036] A carbon-carbon unsaturated double bond is a reactive unsaturated bond. Furthermore, a carbon-carbon unsaturated double bond exhibits crosslinking reactions through radical polymerization. In this disclosure, the carbon-carbon unsaturated double bond does not include aromatic structures. While not particularly limited, examples of carbon-carbon unsaturated double bonds include methacryloyl groups, acryloyl groups, crotonoyl groups, and alkenyl groups.

[0037] The polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond preferably has at least one group selected from the group consisting of formulas (8) and (9) at its molecular terminus. That is, the polyphenylene ether compound having a carbon-carbon unsaturated group is preferably terminally modified by at least one group selected from the group consisting of formulas (8) and (9).

[0038]

[0039] In formula (8), a represents an integer between 0 and 10, and Z represents an arylene group. １ ~R ３ They are all independent of each other. That is, R １ ~R ３ These may be the same group or different groups. Also, R １ ~R ３ represents a hydrogen atom or an alkyl group. In formula (8), if a is 0, it indicates that Z is directly bonded to the end of the polyphenylene ether compound (A). Specific examples of the arylene group include, for example, a phenylene group or a naphthylene group. Furthermore, this arylene group may include derivatives in which the hydrogen atom bonded to the aromatic ring is substituted with a functional group such as an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. The alkyl group is not particularly limited, but for example, preferably has 1 to 18 carbon atoms, and more preferably has 1 to 10 carbon atoms. Specific examples of alkyl groups include, for example, a methyl group, an ethyl group, a propyl group, a hexyl group, or a decyl group.

[0040]

[0041] In formula (9), R ４ represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, but preferably has 1 to 18 carbon atoms, and more preferably has 1 to 10 carbon atoms. Specifically, examples include a methyl group, ethyl group, propyl group, hexyl group, or decyl group. In addition, examples of the group represented by formula (9) include a methacryloyl group or an acryloyl group.

[0042] Furthermore, more specific examples of the group represented by formula (8) include, for example, the vinylbenzyl group (hereinafter also called the ethenylbenzyl group) or vinylphenyl group represented by formula (13). Also, more specific examples of the vinylbenzyl group include, for example, the o-vinylbenzyl group, m-vinylbenzyl group or p-vinylbenzyl group.

[0043]

[0044] The polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond preferably has a polyphenylene ether chain in its molecule and a repeating unit represented by formula (14) in its molecule.

[0045]

[0046] In equation (14), b represents an integer between 1 and 50. Also, R ５ ~R ８ They are all independent of each other. That is, R ５ ~R ８ These may be the same group or different groups. Also, R ５ ~R ８ R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. ５ ~R ８ These are preferably hydrogen atoms and alkyl groups.

[0047] R ５ ~R ８ Specifically, the functional groups mentioned include the following:

[0048] The alkyl group is not particularly limited, but preferably has 1 to 18 carbon atoms, and more preferably has 1 to 10 carbon atoms. Specific examples of alkyl groups include, for example, a methyl group, an ethyl group, a propyl group, a hexyl group, or a decyl group.

[0049] The alkenyl group is not particularly limited, but preferably has 2 to 18 carbon atoms, and more preferably 2 to 10 carbon atoms. Specific examples of alkenyl groups include vinyl groups, allyl groups (2-propenyl groups), or 3-butenyl groups.

[0050] The alkynyl group is not particularly limited, but preferably has 2 to 18 carbon atoms, and more preferably 2 to 10 carbon atoms. Specific examples of alkynyl groups include, for example, the ethynyl group or the propargyl group (propa-2-in-1-yl group).

[0051] The alkylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group, but preferably has 2 to 18 carbon atoms, and more preferably has 2 to 10 carbon atoms. Specific examples of alkylcarbonyl groups include, for example, acetyl group, propionyl group, butyryl group, isobutyryl group, pivaloyl group, hexanoyl group, octanoyl group, or cyclohexylcarbonyl group.

[0052] The alkenylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group, but preferably has 3 to 18 carbon atoms, and more preferably has 3 to 10 carbon atoms. Specific examples of alkenylcarbonyl groups include, for example, acryloyl, methacryloyl, or crotonoyl groups.

[0053] The alkynylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group, but preferably has 3 to 18 carbon atoms, and more preferably 3 to 10 carbon atoms. Specific examples of alkynylcarbonyl groups include, for example, the propioloyl group.

[0054] The number-average molecular weight (Mn) of the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond is preferably 500 to 5000. In this case, the heat resistance of the cured resin composition can be improved. It is presumed that the reason why the heat resistance of the cured resin composition can be improved when the number-average molecular weight of the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond is within the above range is as follows. For example, in the case of a normal polyphenylene ether compound that is not terminally modified by a group having a carbon-carbon unsaturated double bond, if its number-average molecular weight is in the range of 500 to 5000, it is a relatively low molecular weight, and therefore the heat resistance of the cured resin composition containing the polyphenylene ether compound tends to decrease. In contrast, the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond has a carbon-carbon unsaturated double bond at its molecular end, so the heat resistance of the cured resin composition is easily improved. This number-average molecular weight is more preferably 800 or more, and even more preferably 1000 or more. Furthermore, the number-average molecular weight is more preferably 4500 or less, and even more preferably 4000 or less. The number-average molecular weight can be measured by any general molecular weight measurement method, specifically, by measuring it using gel permeation chromatography (GPC) and converting it to polystyrene equivalent.

[0055] Furthermore, if the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond has a repeating unit represented by formula (14) in its molecule, it is preferable that b is a value such that the number average molecular weight of the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond is in the range of 500 to 5000. Specifically, it is preferable that b is 1 to 50.

[0056] The average number of carbon-carbon unsaturated double bond groups (terminal functional groups) per molecule of the polyphenylene ether compound (A) having carbon-carbon unsaturated double bonds is preferably 1 to 5. When this number of terminal functional groups is 1 or more, the heat resistance of the cured resin composition can be further improved. When this number of terminal functional groups is 5 or less, the reactivity of the resin composition can be adjusted, thereby improving the fluidity of the resin composition during molding and improving the storage stability of the resin composition. This number of terminal functional groups is more preferably 1.5 or more. Furthermore, this number of terminal functional groups is more preferably 3 or less.

[0057] The number of terminal functional groups in a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond is a numerical value representing the average number of terminal functional groups per molecule of the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond present in one mole of the compound. This number of terminal functional groups can be measured, for example, by measuring the number of hydroxyl groups remaining in the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond and calculating the decrease from the number of hydroxyl groups of the polyphenylene ether compound before terminal modification. This decrease from the number of hydroxyl groups of the polyphenylene ether compound before terminal modification is the number of terminal functional groups. The number of hydroxyl groups remaining in the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond can be determined by adding a quaternary ammonium salt such as tetraethylammonium hydroxide, which associates with hydroxyl groups, to a solution of the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond and measuring the UV absorbance of the mixed solution.

[0058] The polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond preferably contains at least one of the compounds represented by formula (15) and formula (16).

[0059]

[0060]

[0061] In equations (15) and (16), R９ ~R １６ And R １７ ~R ２４ They are all independent of each other. That is, R ９ ~R １６ And R １７ ~R ２４ These may be the same group or different groups. They represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. X １ and X ２ Each of these independently represents a group having a carbon-carbon unsaturated double bond. Each of A and B represents a repeating unit represented by formula (17) or formula (18), respectively. In formula (16), Y represents a linear, branched, or cyclic hydrocarbon group having 20 or fewer carbon atoms.

[0062]

[0063]

[0064] In equations (17) and (18), c and d each represent an integer between 0 and 20, inclusive. In equations (17) and (18), R ２５ ~R ２８ And R ２９ ~R ３２ They are all independent of each other. That is, R ２５ ~R ２８ And R ２９ ~R ３２ These may each be the same group or different groups. Also, R ２５ ~R ２８ And R ２９ ~R ３２ R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. ２５ ~R ２８ And R ２９ ~R ３２ R is preferably a hydrogen atom and an alkyl group. ２５ ~R ３２ R in equation (14) ５ ~R ８may be the same as

[0065] Also, for c and d in formula (17) and formula (18), the total value of c and d preferably represents an integer of 1 or more and 30 or less. Further, c represents an integer of 0 or more and 20 or less, d represents an integer of 0 or more and 20 or less, and it is more preferable that the sum of c and d represents an integer of 1 or more and 30 or less.

[0066] In formula (19), Y is a linear, branched or cyclic hydrocarbon group having 20 or less carbon atoms. Examples of Y include a group represented by formula (19) and the like.

[0067]

[0068] In formula (19), R ３３ and R ３４ each independently represent a hydrogen atom or an alkyl group. Examples of the alkyl group include a methyl group and the like. Further, specific examples of the group represented by formula (19) include a methylene group, a methylmethylene group, a dimethylmethylene group and the like. R ３３ and R ３４ are preferably a methyl group, and the group represented by formula (19) is preferably a dimethylmethylene group.

[0069] Also, in formula (15) and formula (16), X １ and X ２ are each independent. X １ and X ２ are, for example, groups having a carbon-carbon unsaturated double bond. X １ and X ２ each are, for example, a group represented by formula (8) or formula (9). In the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond represented by formula (8) and formula (9), X １ and X ２ may be the same group or different groups.

[0070] A more specific example of a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond represented by formula (15) is, for example, a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond represented by formula (20).

[0071]

[0072] More specific examples of polyphenylene ether compounds (A) having a carbon-carbon unsaturated double bond represented by formula (16) include, for example, polyphenylene ether compounds (A) having a carbon-carbon unsaturated double bond represented by formula (21) or formula (22).

[0073]

[0074]

[0075] In equations (20) to (22), c and d are the same as c and d in equations (17) and (18). Also, in equations (20) and (21), R １ ~R ３ a and Z are R in equation (8). １ ~R ３ , is the same as a and Z. Also, in equations (21) and (22), Y is the same as Y in equation (16). Also, in equation (22), R ４ R in equation (9) is ４ It is the same as this.

[0076] A method for synthesizing a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond will be described. Specifically, this method involves reacting a starting polyphenylene ether compound with a compound to which a group having a carbon-carbon unsaturated double bond and a halogen atom are bonded.

[0077] The polyphenylene ether compound used as a raw material is not particularly limited, as long as it can synthesize a polyphenylene ether compound (A) having a predetermined carbon-carbon unsaturated double bond. Specifically, examples include polyphenylene ethers composed of 2,6-dimethylphenol and at least one of a difunctional phenol and a trifunctional phenol, and polyphenylene ether compounds such as poly(2,6-dimethyl-1,4-phenylene oxide). A difunctional phenol is a phenol compound having two phenolic hydroxyl groups in one molecule, such as tetramethylbisphenol A. A trifunctional phenol is a phenol compound having three phenolic hydroxyl groups in one molecule.

[0078] The method for synthesizing the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond is the method described above. Specifically, the polyphenylene ether compound described above and a compound to which a group having a carbon-carbon unsaturated double bond and a halogen atom are bonded are dissolved in a solvent and stirred. As a result, the polyphenylene ether compound and the compound to which the group having a carbon-carbon unsaturated double bond and a halogen atom are bonded react to obtain the polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond.

[0079] It is preferable that the reaction between a polyphenylene ether compound and a compound having a carbon-carbon unsaturated double bond and a halogen atom be carried out in the presence of an alkali metal hydroxide. This is thought to allow the reaction to proceed favorably. This is because the alkali metal hydroxide is thought to function as a dehalogenating agent. In other words, the alkali metal hydroxide removes hydrogen halides from the phenolic hydroxyl group of the polyphenylene ether compound and the compound having a carbon-carbon unsaturated double bond and a halogen atom, and it is thought that the group having a carbon-carbon unsaturated double bond replaces the hydrogen atom of the phenolic hydroxyl group of the polyphenylene ether compound by bonding to the oxygen atom of the phenol group.

[0080] Alkali metal hydroxides are not particularly limited as long as they act as dehalogenating agents, but examples include sodium hydroxide. Furthermore, alkali metal hydroxides are usually used in aqueous solution form, specifically as an aqueous solution of sodium hydroxide.

[0081] The reaction conditions, such as reaction time and reaction temperature, vary depending on the compound, including the group having a carbon-carbon unsaturated double bond and the halogen atom, and are not particularly limited as long as the conditions allow the above-mentioned reaction to proceed favorably. Specifically, the reaction temperature is preferably 20°C to 100°C, and more preferably 30°C to 100°C. The reaction time is preferably 0.5 hours to 20 hours, and more preferably 0.5 hours to 10 hours.

[0082] The solvent used in the reaction between a polyphenylene ether compound and a compound to which a group having a carbon-carbon unsaturated double bond and a halogen atom are bonded is not particularly limited, as long as it can dissolve the polyphenylene ether compound and the compound to which the group having a carbon-carbon unsaturated double bond and a halogen atom are bonded, and does not inhibit the reaction between the polyphenylene ether compound and the compound to which the group having a carbon-carbon unsaturated double bond and a halogen atom are bonded. Specifically, examples include toluene.

[0083] The reaction between a polyphenylene ether compound and a compound having a carbon-carbon unsaturated double bond and a halogen atom is preferably carried out in the presence of not only an alkali metal hydroxide but also a phase-transfer catalyst. In other words, the above reaction is preferably carried out in the presence of an alkali metal hydroxide and a phase-transfer catalyst. This is thought to allow the above reaction to proceed more favorably. This is thought to be because the phase-transfer catalyst has the function of incorporating alkali metal hydroxides, is soluble in both the polar solvent phase such as water and the non-polar solvent phase such as an organic solvent, and can move between these phases. Specifically, when an aqueous sodium hydroxide solution is used as the alkali metal hydroxide and an organic solvent such as toluene, which is immiscible with water, is used as the solvent, even if the aqueous sodium hydroxide solution is added dropwise to the solvent being used in the reaction, the solvent and the aqueous sodium hydroxide solution will separate, and it is thought that the sodium hydroxide will not easily migrate into the solvent. In that case, it is thought that the aqueous sodium hydroxide solution added as the alkali metal hydroxide will not contribute much to promoting the reaction. In contrast, when the reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst, the alkali metal hydroxide is incorporated into the phase transfer catalyst and migrates to the solvent, and the aqueous sodium hydroxide solution is thought to contribute more readily to promoting the reaction. For this reason, the above reaction is thought to proceed more favorably when carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst. The phase transfer catalyst is not particularly limited, but examples include quaternary ammonium salts such as tetra-n-butylammonium bromide.

[0084] The content of polyphenylene ether compound (A) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, based on the total amount of resin components in the resin composition. In this case, the dielectric loss tangent of the cured product of the resin composition can be reduced. Alternatively, the content of polyphenylene ether compound (A) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, based on the total amount of resin components in the resin composition. In this case, the crosslinking reaction between polyphenylene ether compound (A) and maleimide compound (B) proceeds favorably, and the heat resistance of the cured product of the resin composition can be improved. Here, the total amount of resin components is the sum of polyphenylene ether (A), maleimide compound (B), and free radical compound (C). The resin composition may also contain other thermosetting compounds different from these compounds (hereinafter also referred to as thermosetting resin components (R)). In such cases, the total amount of resin components refers to the sum of polyphenylene ether (A), maleimide compound (B), free radical compound (C), and thermosetting resin component (R). Details of the thermosetting resin component (R) will be described later.

[0085] <Maleimide Compound> As described above, the resin composition contains maleimide compound (B). Maleimide compound (B) is a component that can improve the heat resistance of the cured product of the resin composition.

[0086] The functional group equivalent of maleimide compound (B) is 230 g / eq. or more, preferably 240 g / eq. or more, and more preferably 250 g / eq. or more. In this case, the dielectric loss tangent of the cured resin composition is reduced, and deterioration of water absorption can be suppressed. Alternatively, the functional group equivalent of maleimide compound (B) is 500 g / eq. or less, preferably 400 g / eq. or less. If the functional group equivalent of maleimide compound (B) is greater than 500 g / eq., the reactivity of the crosslinking reaction between polyphenylene ether compound (A) and maleimide compound (B) decreases, which may reduce the heat resistance of the cured resin composition.

[0087] The maleimide compound (B) may contain only one kind of compound, or may contain two or more kinds of compounds. Examples of the maleimide compound (B) include a monofunctional maleimide compound having one maleimide group in one molecule or a polyfunctional maleimide compound having two or more maleimide groups in one molecule.

[0088] The maleimide compound (B) may contain an aromatic maleimide compound (B1) having a phenylmaleimide group, or may contain an aliphatic maleimide compound (B2) not having a phenylmaleimide group. That is, the maleimide compound (B) may contain only the aromatic maleimide compound (B1), may contain only the aliphatic maleimide compound (B2), or may contain both the aromatic maleimide compound (B1) and the aliphatic maleimide compound (B2).

[0089] The aromatic maleimide compound (B1) is not particularly limited, and examples thereof include 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, polyphenylmethane maleimide, a maleimide compound represented by the formula (23), a maleimide compound represented by the formula (24), and the like.

[0090]

[0091] In the formula (23), e represents an integer of 1 or more and 5 or less. In the formula (23), R ３５ ~R ３８ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group. Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, or a neopentyl group. R ３５ ~R ３８ are preferably hydrogen atoms.

[0092]

[0093] In the formula (24), f represents an integer of 1 or more and 10 or less, and preferably represents an integer greater than 1 and less than 5.

[0094] The aliphatic maleimide compound (B2) is not particularly limited, but examples include the maleimide compound represented by formula (25).

[0095]

[0096] When the maleimide compound (B) includes an aromatic maleimide compound (B1) and an aliphatic maleimide compound (B2), the mass ratio of the aromatic maleimide compound (B1) to the aliphatic maleimide compound (B2) is not particularly limited, but is for example 87:13 to 30:70.

[0097] The content of maleimide compound (B) is preferably 9% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on the total amount of resin components in the resin composition. In this case, heat resistance can be improved. Alternatively, the content of maleimide compound (B) is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less, based on the total amount of resin components in the resin composition. In this case, deterioration of dielectric loss tangent and water absorption can be suppressed. The numerical values ​​for the content of maleimide compound (B) are rounded to the first decimal place, along with the value for polyphenylene ether compound (A). Therefore, the total amount of resin components in the resin composition does not exceed 100% by mass. Furthermore, the content of maleimide compound (B) can be used within the above preferred range depending on the content of each component of the resin components of the resin composition, such as polyphenylene ether compound (A) and free radical compound (C).

[0098] <Free Radical Compounds> As described above, the resin composition contains free radical compounds (C). Free radical compounds (C) are components that can improve the resin flowability, circuit filling properties, and storage stability of the resin composition, as well as the laser processability of its cured product.

[0099] The free radical compound (C) in this disclosure is a compound used to control the radical polymerization reaction. Polyphenylene ether compound (A) has high radical polymerization reactivity and readily polymerizes with other polyphenylene ether compounds (A), so the radical polymerization reaction between polyphenylene ether compound (A) and maleimide compound (B) does not proceed uniformly. Therefore, by adding the free radical compound (C), the polymerization reaction between polyphenylene ether compounds (A) is suppressed, and it is presumed that the radical polymerization reaction between polyphenylene ether compound (A) and maleimide compound (B) proceeds uniformly. In this way, the high radical polymerization reactivity of polyphenylene ether compound (A) can be reduced, which improves the resin flowability of the resin composition, and as a result, the circuit filling ability may be improved. Furthermore, since the radical polymerization reaction between polyphenylene ether compound (A) and maleimide compound (B) proceeds uniformly, the crosslinking density of the cured resin composition is improved, which may improve laser processability.

[0100] The molecular weight of the free radical compound (C) is between 160 and 800. In particular, if the molecular weight is less than 160, the free radical compound (C) may volatilize, potentially making it impossible to control the radical polymerization reaction.

[0101] A free radical compound (C) has at least one free radical in its molecule. More specifically, a free radical compound (C) has at least one selected from the group consisting of groups represented by formulas (1), (2), (3), and (4).

[0102]

[0103]

[0104]

[0105]

[0106] Furthermore, the free radical compound (C) may have at least one compound selected from the group consisting of compounds represented by formulas (5), (6), and (7).

[0107]

[0108] In formula (5), X Ａ This group exhibits an ether bond with an amino group, cyano group, hydroxyl group, isothiocyanate group, carboxyl group, oxo group, amide group, acyloxy group, or organic group. Examples of amide groups include acetamide. Examples of acyloxy groups include benzoyloxy, formyloxy, and acetyloxy groups. Examples of organic groups include methyl.

[0109]

[0110] In formula (6), X Ｂ This group exhibits an ether bond with a cyano group, isothiocyanate group, carboxyl group, amide group, acyloxy group, or organic group. Examples of amide groups include acetamide. Examples of acyloxy groups include benzoyloxy, formyloxy, and acetyloxy groups. Examples of organic groups include methyl.

[0111]

[0112] In formula (7), X Ｃ The symbol represents an alkylene group, an aromatic structure, a carbonyl group, an amide group, or an oxygen atom. Examples of alkylene groups include methylene group, dimethylmethylene group, ethylene group, propylene group, n-butylene group, sec-butylene group, tert-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, and n-octylene group. Examples of aromatic structures include phenylene group, naphthalene group, and biphenyl structure.

[0113] The free radical compound (C) may contain only one compound or two or more compounds.

[0114] The content of the free radical compound (C) is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and even more preferably 0.05 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B). In this case, the resin flowability, circuit filling ability, and laser processability of the cured product of the resin composition can be improved. Alternatively, the content of the free radical compound (C) is preferably 1 part by mass or less, more preferably 0.75 parts by mass or less, and even more preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B). In this case, deterioration of the dielectric loss tangent, metal peel strength, and heat resistance of the cured product of the resin composition can be suppressed.

[0115] <Inorganic Filler> As described above, the resin composition contains inorganic filler (D). Inorganic filler (D) is a component that can reduce the coefficient of linear expansion of the cured product of the resin composition.

[0116] The inorganic filler (D) is not particularly limited, but examples include silica such as synthetic silica, fused silica, or crystalline silica, talc, boehmite, magnesium hydroxide, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, clay, and mica. The inorganic filler (D) contained in the resin composition may be one type or two or more types.

[0117] The inorganic filler (D) may be surface-treated with a silane coupling agent. The silane coupling agent is not particularly limited, but examples include vinyltriethoxysilane, vinyltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropylethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, glycidoxypropyltriethoxysilane, isocyanatetopropyltriethoxysilane, and the like. The silane coupling agent used may be a single type or a combination of two or more types.

[0118] The content of inorganic filler (D) is preferably 10 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 70 parts by mass or more, based on 100 parts by mass of the total of polyphenylene ether compound (A) and maleimide compound (B). In this case, the coefficient of linear expansion of the cured resin composition can be reduced. Alternatively, the content of inorganic filler (D) is preferably 250 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less, based on 100 parts by mass of the total of polyphenylene ether compound (A) and maleimide compound (B). In this case, deterioration of the circuit filling properties of the resin composition can be suppressed.

[0119] <Phenol Compounds> As described above, the resin composition does not contain phenol compounds, or the resin composition contains phenol compounds, and the content of the phenol compounds is 0.01% by mass or less with respect to the total amount of solids in the resin composition. If this content exceeds 0.01% by mass, the dielectric loss tangent and water absorption rate of the cured resin composition deteriorate. In other words, the resin composition may contain phenol compounds as long as the content of the phenol compounds is 0.01% by mass or less with respect to the total amount of solids in the resin composition. Furthermore, it is preferable that the resin composition does not contain phenol compounds. Here, "solids in the resin composition" in this disclosure refers to the sum of all components of the resin composition excluding the solvent.

[0120] More specifically, the phenol compound has a structure represented by formula (26), for example.

[0121]

[0122] Here, since hydroxyl groups are polar groups, phenol compounds are polar. Therefore, when a resin composition contains a phenol compound, orientational polarization occurs, and the dielectric loss tangent increases. Also, since hydroxyl groups are hydrophilic, the water absorption rate increases.

[0123] Compared to other compounds such as polyphenylene ether compounds (A) and maleimide compounds (B), phenol compounds have a large number of hydroxyl groups, resulting in a high hydroxyl group concentration. Therefore, if a resin composition contains a phenol compound in a proportion exceeding 0.01% by mass relative to the total amount of solids in the resin composition, the dielectric loss tangent and water absorption rate of the cured resin composition deteriorate. The resin composition of this disclosure does not, as described above, or the resin composition contains a phenol compound, and the content of the phenol compound is 0.01% by mass or less relative to the total amount of solids in the resin composition, so the dielectric loss tangent and water absorption rate of the cured resin composition can be good.

[0124] <Additives> The resin composition may, if necessary, contain additives in addition to the components described above, as long as they do not impair the effects of this embodiment. The components of the additives and their content are not particularly limited.

[0125] The additives are not particularly limited, but examples include thermosetting resin components (R), thermoplastic resins, flame retardants, colorants, coupling agents, heat stabilizers, antioxidants, polymerization initiators, defoamers, antistatic agents, dyes, pigments, lubricants, and the like.

[0126] As described above, the resin components of the resin composition may include, in addition to the polyphenylene ether compound (A), maleimide compound (B), and free radical compound (C), other thermosetting compounds (thermosetting resin component (R)). The thermosetting resin component (R) is not particularly limited, but examples include benzoxazine compounds, epoxy compounds, unsaturated imide compounds, cyanate compounds, isocyanate compounds, oxetane compounds, amino compounds, unsaturated polyester compounds, allyl compounds, silicone compounds, triazine compounds, melamine compounds, etc. However, from the viewpoint of suppressing deterioration of the water absorption rate of the cured product, it is preferable that the resin composition does not contain cyanate compounds as thermosetting resin component (R).

[0127] (1.2) Physical properties of resin compositions, their semi-cured products, and cured products will be described.

[0128] <Water Absorption Rate> The cured product of the resin composition has a good water absorption rate. If the water absorption rate is too high, the dielectric loss tangent deteriorates.

[0129] The water absorption rate of the cured resin composition is preferably less than 0.35%.

[0130] <Dielectric Loss Tangent> The cured resin composition has a good dielectric loss tangent under normal conditions. Furthermore, the cured resin composition suppresses the deterioration of the dielectric loss tangent after water absorption.

[0131] The dielectric loss tangent of the cured resin composition at 10 GHz under normal conditions is preferably less than 0.0040. Furthermore, the dielectric loss tangent of the cured resin composition at 10 GHz after water absorption treatment is preferably less than 0.0080.

[0132] <Circuit Filling Properties> The resin composition and its semi-cured product have good circuit filling properties. If the circuit filling properties are insufficient, voids and the like will be generated in the circuit when the product is cured after filling.

[0133] <Resin Flowability> The resin composition and its semi-cured product have good resin flowability. If the resin flowability is too low, the spaces between the wires in the wiring board will not be sufficiently filled, and gaps, voids, etc. will occur in the insulating layer of the wiring board. In other words, good resin flowability results in good circuit filling.

[0134] <Metal Peel Strength> The cured resin composition has good metal peel strength. Specifically, it has good metal peel strength between the cured resin composition and the metal foil when they are in close contact. In other words, the adhesion between the cured resin composition and the metal foil is good and it is difficult to peel off, so the metal-clad laminates and wiring boards manufactured from the resin composition have excellent reliability.

[0135] The metal peel strength of the cured resin composition is preferably 0.60 N / mm or higher.

[0136] <Laser Processability> The cured resin composition has good laser processability. If the laser processability is not good, the diameter of the via holes formed by the laser may become too large, and the metal foil between the via holes may peel off. If the metal foil between the via holes peels off, a good circuit pattern cannot be formed on the wiring board. On the other hand, if the laser processability is good, the diameter of the via holes can be reduced, and the metal foil between the via holes does not peel off, so a good circuit pattern can be formed on the wiring board, including miniaturization. Examples of lasers that can be used include carbon dioxide lasers, UV lasers, and excimer lasers.

[0137] (1.3) Preparation Method Methods for preparing the resin composition include, for example, mixing a polyphenylene ether compound (A), a maleimide compound (B), a free radical compound (C), and an inorganic filler (D) in predetermined amounts, but are not particularly limited. Additives may be added and mixed as needed.

[0138] Furthermore, the resin composition may contain an organic solvent. That is, it is preferable that the resin composition be used as a varnish-state resin composition containing an organic solvent. A varnish-state resin composition is one in which an organic solvent is further added to the components contained in the above-mentioned resin composition.

[0139] The above-mentioned varnished resin composition is prepared as follows. First, components of the resin composition that can be dissolved in an organic solvent are added to the organic solvent, stirred, and mixed to prepare a mixture. Alternatively, this mixture may be prepared by stirring and mixing while heating. Next, components that cannot be dissolved in the organic solvent are added to the above mixture, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, etc., until the desired dispersion state is reached, thereby preparing a varnished resin composition. The organic solvent used here is not particularly limited, but it is preferable that it can dissolve, for example, polyphenylene ether compounds (A), maleimide compounds (B), free radical compounds (C), etc., and does not inhibit the crosslinking reaction of the resin composition. Specifically, examples of organic solvents include toluene and methyl ethyl ketone (MEK).

[0140] (2) Examples of applications of the resin composition Examples of applications of the resin composition will be explained with reference to Figures 1 to 5.

[0141] By using a resin composition, a prepreg 1, a resin-coated film 2, a resin-coated metal foil 3, a metal-clad laminate 4, and a wiring board 5 can be obtained.

[0142] More specifically, the prepreg 1 includes at least one of the resin composition and a semi-cured product of the resin composition. The resin layer 21 of the resin-coated film 2 includes at least one of the resin composition and a semi-cured product of the resin composition. The resin layer 31 of the resin-coated metal foil 3 includes at least one of the resin composition and a semi-cured product of the resin composition. The insulating layer 41 of the metal-clad laminate 4 includes a cured product of the resin composition. The insulating layer 51 of the wiring board 5 includes a cured product of the resin composition.

[0143] In this embodiment, the resin composition is in an uncured state, soluble in certain liquids, and fusible, representing an initial stage. That is, the resin composition is in Stage A.

[0144] Furthermore, in this embodiment, a semi-cured product is a resin composition that has been partially cured to the extent that it can be further cured. For example, when the resin composition according to this embodiment is heated, the viscosity gradually decreases at the beginning of heating, but gradually increases as the curing of the resin composition begins. Thus, a semi-cured product is a resin composition that has been partially cured, and is what is known as a B-stage resin composition.

[0145] (2.1) Prepreg Figure 1 is a schematic cross-sectional view showing an example of prepreg 1 according to this embodiment.

[0146] The prepreg 1 comprises at least one of a resin composition and a semi-cured product of the resin composition. The prepreg 1 may also comprise a resin layer 11, as shown in Figure 1. That is, the resin layer 11 comprises at least one of a resin composition and a semi-cured product of the resin composition. The resin layer 11 further comprises a fibrous substrate 12. In other words, the prepreg 1 may comprise a resin layer 11 in which the fibrous substrate 12 is impregnated with at least one of a resin composition and a semi-cured product of the resin composition.

[0147] Furthermore, the prepreg 1 obtained using the resin composition may include a semi-cured product of the resin composition, as described above, or it may include an uncured resin composition, i.e., an uncured product of the resin composition.

[0148] As described above, the prepreg 1 may include a resin layer 11 formed by impregnating a fibrous substrate 12 with at least one of a resin composition and a semi-cured product of the resin composition. When impregnating the fibrous substrate 12 with at least one of the resin composition and the semi-cured product of the resin composition, it is preferable to use a varnish manufactured from the resin composition. Also, as shown in Figure 1, the prepreg 1 has one fibrous substrate 12, but it may have two or more fibrous substrates 12.

[0149] The fibrous base material 12 is a reinforcing material and is not particularly limited, but examples include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, linter paper, etc. By using glass cloth, a laminate with excellent mechanical strength can be obtained. It is particularly preferable that the glass cloth is flattened. Specifically, as a flattening process, a method of continuously pressing the glass cloth with a press roll at an appropriate pressure to flatten the yarn can be used. The thickness of the fibrous base material 12 used in general is not particularly limited, but for example, it is 5 μm to 300 μm. The glass cloth contains glass fibers, but may also contain reinforcing fibers other than glass fibers. The glass cloth may be surface-treated with a coupling agent or the like before impregnation with the varnish-state resin composition. Surface treatment of the glass cloth can improve the adhesion between the glass cloth and the resin composition. The coupling agent used for surface treatment is not particularly limited, but examples include those that can be used with the inorganic filler (D) described above.

[0150] Furthermore, in order to obtain the resin layer 11, the fibrous substrate 12 is impregnated with varnish by either immersing it in varnish or applying varnish to the fibrous substrate 12. This impregnation can be repeated multiple times as needed. In addition, by repeatedly impregnating with multiple varnishes having different compositions and concentrations, a resin layer 11 containing a resin composition or a semi-cured resin composition with the desired composition and impregnation amount can be obtained.

[0151] Furthermore, regarding the method for producing the prepreg 1, for example, the organic solvent may be reduced or removed from the resin layer 11 by heating the resin layer 11, which is produced by impregnating a fibrous substrate 12 with a varnish containing a resin composition and an organic solvent. When reducing or removing the organic solvent from the resin layer 11 by heating the resin layer 11, for example, the temperature is 80°C or higher and 180°C or lower, and the time is 1 minute or higher and 10 minutes or lower.

[0152] The method for producing the prepreg 1 comprising at least one of the resin composition and the semi-cured product of the resin composition according to this embodiment, and a fibrous base material 12, is not limited to the method described above. In other words, the prepreg 1 produced using the resin composition according to this embodiment can be produced by any appropriate method.

[0153] Since the prepreg 1 according to this embodiment is manufactured using the resin composition according to this embodiment, it can achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0154] (2.2) Resin-coated film Figure 2 is a schematic cross-sectional view showing an example of a resin-coated film 2 according to this embodiment.

[0155] The resin-coated film 2 comprises a resin layer 21 containing at least one of a resin composition and a semi-cured product of the resin composition, and a support film 22. That is, the resin-coated film 2 comprises a resin layer 21 containing at least one of a resin composition and a semi-cured product of the resin composition, and a support film 22 overlapping the resin layer 21. The resin-coated film 2 may also have other layers between the resin layer 21 and the support film 22.

[0156] Furthermore, as described above, the resin layer 21 may contain a semi-cured product of the resin composition, or it may contain an uncured product of the resin composition that has not yet hardened. In other words, the resin-coated film 2 may be a resin-coated film 2 comprising a resin layer 21 containing a semi-cured product of the resin composition and a support film 22, or it may be a resin-coated film 2 comprising a resin layer 21 containing an uncured product of the resin composition before hardening and a support film 22.

[0157] The resin layer 21 may or may not contain a fibrous substrate (not shown). If the resin layer 21 contains a fibrous substrate, the same type of fibrous substrate as the fibrous substrate 12 of the prepreg 1 can be used. In other words, the resin layer 21 may be manufactured from the prepreg 1.

[0158] The support film 22 supports the resin layer 21. This support of the resin layer 21 by the support film 22 makes the resin layer 21 easier to handle. The support film 22 is not particularly limited, but for example, it is an electrically insulating film. Examples of support films 22 include polyethylene terephthalate (PET) film, polyimide film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, and polyarylate film.

[0159] A release agent layer (not shown) may be provided on the surface of the support film 22 that supports the resin layer 21. This release agent layer allows the support film 22 to be peeled off from the resin layer 21 as needed. Preferably, the support film 22 is peeled off from the insulating layer after the resin layer 21 has been cured to form an insulating layer.

[0160] In Figure 2, one side of the resin layer 21 is covered by the support film 22, but the other side of the resin layer 21 may be covered by a cover film (not shown). By covering both sides of the resin layer 21, the resin layer 21 can be made easier to handle and the adhesion of foreign matter to the resin layer 21 can be suppressed.

[0161] The cover film is not particularly limited, but for example, it is an electrically insulating film. Examples of cover films include polyethylene terephthalate (PET) film, polyolefin film, polyester film, and polymethylpentene film. A release agent layer may also be provided between the resin layer 21 and the cover film. The release agent layer allows the cover film to be peeled off from the resin layer 21 as needed.

[0162] Furthermore, the support film 22 and the cover film may be subjected to surface treatments such as matte treatment, corona treatment, release treatment, or roughening treatment, as needed.

[0163] The resin layer 21 is manufactured by applying a resin composition to the support film 22. The method of applying the resin composition is not particularly limited, but for example, a bar coater, die coater, doctor blade, baker applicator, etc., can be used. When applying the resin layer 21 to the support film 22, it is preferable to use a resin composition in a varnish state. As described above, by heating the varnish applied on the support film 22, the organic solvent can be volatilized from the varnish, thereby reducing or removing the organic solvent. The applied varnish is heated, for example, at a temperature of 80°C to 180°C for a time of 1 minute to 10 minutes. That is, the conditions for reducing or removing the organic solvent from the resin layer 21 by heating the resin layer 21 may be the same as the conditions for reducing or removing the organic solvent from the resin layer 11 by heating the resin layer 11 when manufacturing the prepreg 1. In this way, a resin layer 21 containing at least one of the resin composition and a semi-cured product of the resin composition is formed on the support film 22, thereby manufacturing a resin-coated film 2.

[0164] The method for producing the resin-coated film 2, which comprises a resin layer 21 containing the resin composition or a semi-cured product of the resin composition according to this embodiment, and a support film 22 supporting the resin layer 21, is not limited to the method described above. In other words, the resin-coated film 2 produced using the resin composition according to this embodiment can be produced by any suitable method.

[0165] Since the resin-coated film 2 according to this embodiment is manufactured using the resin composition according to this embodiment, it can achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0166] (2.3) Resin-coated metal foil Figure 3 is a schematic cross-sectional view showing an example of resin-coated metal foil 3 according to this embodiment.

[0167] The resin-coated metal foil 3 comprises a resin layer 31 containing at least one of a resin composition and a semi-cured product of the resin composition, and a metal foil 32. The resin-coated metal foil 3 may also have other layers between the resin layer 31 and the metal foil 32.

[0168] As described above, the resin layer 31 may contain a semi-cured resin composition or an uncured resin composition. That is, the resin-coated metal foil 3 may be a resin-coated metal foil 3 comprising a resin layer 31 containing a semi-cured resin composition and a metal foil 32, or it may be a resin-coated metal foil 3 comprising a resin layer 31 containing an uncured resin composition before curing and a metal foil 32.

[0169] The resin layer 31 may or may not contain a fibrous substrate (not shown). If the resin layer 31 contains a fibrous substrate, the same type of fibrous substrate as the fibrous substrate 12 of the prepreg 1 can be used. In other words, the resin layer 31 can be manufactured from the prepreg 1.

[0170] The metal foil 32 is not particularly limited, but examples include copper foil and aluminum foil. The metal foil 32 can be used as wiring 52 of the wiring board 5 after unnecessary portions are removed by etching using a subtractive method or the like.

[0171] Furthermore, the resin-coated metal foil 3 may be equipped with a cover film (not shown) or the like, if necessary. The same cover film used for the resin-coated film 2 described above can be used.

[0172] The resin layer 31 is manufactured by applying a resin composition to the metal foil 32. The method of applying the resin composition is not particularly limited, but examples include using a bar coater, die coater, doctor blade, baker applicator, etc. When applying the resin composition to the metal foil 32, it is preferable to use a resin composition in a varnish state.

[0173] As described above, by heating the varnish applied to the metal foil 32, the organic solvent can be volatilized from the varnish, thereby reducing or removing the organic solvent. The applied varnish can be heated, for example, at a temperature of 80°C to 180°C for a time of 1 minute to 10 minutes. In other words, the conditions for reducing or removing the organic solvent from the resin layer 31 by heating the resin layer 31 may be the same as the conditions for reducing or removing the organic solvent from the resin layer 11 by heating the resin layer 11 when preparing the prepreg 1.

[0174] The method for producing the resin-coated metal foil 3, which comprises a resin layer 31 containing the resin composition or a semi-cured product of the resin composition according to this embodiment, and a metal foil 32 adhered to the resin layer 31, is not limited to the method described above. In other words, the resin-coated metal foil 3 produced using the resin composition according to this embodiment can be produced by any appropriate method.

[0175] Since the resin-coated metal foil 3 according to this embodiment is manufactured using the resin composition according to this embodiment, it can achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0176] (2.4) Metal-clad laminate Figure 4 is a schematic cross-sectional view showing an example of a metal-clad laminate 4 according to this embodiment.

[0177] The metal-clad laminate 4 comprises an insulating layer 41 containing a cured product of the resin composition according to this embodiment, and a metal foil 42 overlapping the insulating layer 41.

[0178] One method for manufacturing the metal-clad laminate 4 is to layer a resin composition or a semi-cured resin composition with a metal foil 42, heat and pressurize it to cure the resin composition and form an insulating layer 41, thereby manufacturing the metal-clad laminate 4. More specifically, a metal foil 42 such as copper foil is layered on one or both sides of a resin composition or a semi-cured resin composition, the resin composition or semi-cured resin composition and the metal foil 42 are heated and pressurized to cure the resin composition and form an insulating layer 41, and the insulating layer 41 containing the cured resin composition and the metal foil 42 are laminated and integrated to manufacture a metal-clad laminate 4 in which the metal foil 42 is in close contact with one or both sides of the insulating layer 41 containing the cured resin composition.

[0179] Furthermore, the insulating layer 41 may be manufactured using the prepreg 1 described above. More specifically, the prepreg 1 and the metal foil 42 can be heated and pressurized to cure the prepreg 1 and form the insulating layer 41. By laminating and integrating the insulating layer 41 containing the cured prepreg 1 and the metal foil 42, a metal-clad laminate 4 can be manufactured in which the metal foil 42 is in close contact with one or both sides of the insulating layer 41 containing the cured prepreg 1. When the metal-clad laminate 4 is manufactured using the prepreg 1, the insulating layer 41 contains a fibrous base material (not shown). There may be only one fibrous base material, or there may be two or more.

[0180] Furthermore, the insulating layer 41 may be manufactured using the resin-coated film 2 and resin-coated metal foil 3 described above. More specifically, the resin layer 21 of the resin-coated film 2 or the resin layer 31 of the resin-coated metal foil 3 and the metal foil 42 are heated and pressurized to cure the resin layer 21 of the resin-coated film 2 or the resin layer 31 of the resin-coated metal foil 3 to form the insulating layer 41. By laminating and integrating the insulating layer 41, which includes the cured resin layer 21 of the resin-coated film 2 or the cured resin layer 31 of the resin-coated metal foil 3, with the metal foil 42, a metal-clad laminate 4 can be manufactured in which the metal foil 42 is in close contact with one or both sides of the insulating layer 41, which includes the cured resin layer 21 of the resin-coated film 2 or the cured resin layer 31 of the resin-coated metal foil 3. In this case, when manufactured using the resin-coated metal foil 3, the metal foil 32 of the resin-coated metal foil 3 becomes the metal foil 42 in the metal-clad laminate 4.

[0181] When manufacturing the metal-clad laminate 4, the thickness of the metal foil 42 can be appropriately set according to the desired purpose. Furthermore, the heating and pressing conditions when manufacturing the metal-clad laminate 4 can be appropriately set depending on the thickness of the metal-clad laminate 4 to be manufactured and the type and components of the resin composition that forms the insulating layer 41. In addition, when using an ultra-thin metal foil as the metal foil 42, a carrier-equipped metal foil with a release layer and carrier may be used to improve handling.

[0182] The method for manufacturing the metal-clad laminate 4, which comprises an insulating layer 41 containing a cured resin composition or prepreg 1 according to this embodiment, and a metal foil 42 adhered to the insulating layer 41, is not limited to the method described above. In other words, the metal-clad laminate 4 manufactured using the resin composition or prepreg 1 according to this embodiment can be manufactured by any appropriate method.

[0183] Since the metal-clad laminate 4 according to this embodiment is manufactured using the resin composition according to this embodiment, it can achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0184] (2.5) Wiring board Figure 5 is a schematic cross-sectional view showing an example of a wiring board 5 according to this embodiment.

[0185] The wiring board 5 comprises an insulating layer 51 containing a cured resin composition and wiring 52 overlapping the insulating layer 51. The wiring 52 may be formed on only one side of the insulating layer 51 or on both sides.

[0186] The insulating layer 51 may include the cured product of the prepreg 1 described above. That is, the wiring board 5 comprises an insulating layer 51 manufactured using the prepreg 1 and wiring 52 overlapping the insulating layer 51. The wiring 52 may be formed on only one side of the insulating layer 51 or on both sides. When the wiring board 5 is manufactured using the prepreg 1, it has a fibrous base material (not shown). There may be only one fibrous base material or there may be two or more.

[0187] Furthermore, the wiring board 5 may be manufactured using the metal-clad laminate 4 described above. More specifically, the wiring 52 can be formed by etching or the like on the metal foil 42 on the surface of the metal-clad laminate 4. That is, the wiring board 5 can be formed by partially removing the metal foil 42 on the surface of the metal-clad laminate 4. In this way, a wiring board 5 can be manufactured that comprises an insulating layer 51 and wiring 52 as circuits on one or both sides of the insulating layer 51.

[0188] In addition to the methods described above, other methods for circuit formation are not particularly limited, but examples include circuit formation using the semi-additive process (SAP) and the modified semi-additive process (MSAP).

[0189] Since the wiring board 5 according to this embodiment is manufactured using the resin composition according to this embodiment, it can achieve excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0190] 3. Aspects As will be clear from the above embodiments, this disclosure includes the following aspects. Hereafter, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0191] A resin composition according to a first aspect of the present disclosure contains a polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond, a maleimide compound (B) in an amount of 230 g / eq. to 500 g / eq., a free radical compound (C) having a molecular weight of 160 to 800 and having at least one group selected from the group consisting of formulas (1), (2), (3), and (4), and an inorganic filler (D). The resin composition does not contain a phenol compound, or the resin composition contains a phenol compound, and the content of the phenol compound is 0.01% by mass or less with respect to the total amount of solids in the resin composition.

[0192]

[0193]

[0194]

[0195]

[0196] According to this embodiment, the resin composition achieves excellent circuit filling properties, dielectric loss tangent, water absorption rate, and laser processability.

[0197] In the first embodiment, the resin composition according to the second aspect of the present disclosure comprises an aromatic maleimide compound (B1) having a phenylmaleimide group, wherein the maleimide compound (B) comprises an aromatic maleimide compound (B1).

[0198] In the third aspect of the present disclosure, the resin composition comprises, in the first or second aspect, an aliphatic maleimide compound (B) (B2).

[0199] In any one embodiment of the first to third embodiments, the resin composition comprises a free radical compound (C) selected from the group consisting of compounds represented by formulas (5), (6), and (7).

[0200]

[0201] In formula (5), X Ａ This indicates an ether bond with an amino group, cyano group, hydroxyl group, isothiocyanate group, carboxyl group, oxo group, amide group, acyloxy group, or organic group.

[0202]

[0203] In formula (6), X Ｂ This indicates an ether bond with a cyano group, isothiocyanate group, carboxyl group, amide group, acyloxy group, or organic group.

[0204]

[0205] In formula (7), X Ｃ This represents an alkylene group, an aromatic structure, a carbonyl group, an amide group, or an oxygen atom.

[0206] In the fifth aspect of the present disclosure, the resin composition, in any one of the first to fourth aspects, contains a free radical compound (C) in an amount of 0.01 parts by mass or more and 1 part by mass or less, based on 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B).

[0207] In the sixth aspect of the present disclosure, the resin composition, in any one of the first to fifth aspects, contains an inorganic filler (D) in an amount of 10 to 250 parts by mass with respect to 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B).

[0208] In the seventh aspect of the present disclosure, the resin composition, in any one of the first to sixth aspects, comprises a polyphenylene ether compound (A) having at least one selected from the group consisting of groups represented by formula (8) and formula (9).

[0209]

[0210] In formula (8), a represents an integer between 0 and 10, Z represents an arylene group, and R １ ~R ３ Each of these independently represents either a hydrogen atom or an alkyl group.

[0211]

[0212] In formula (9), R ４ This represents a hydrogen atom or an alkyl group.

[0213] In the eighth aspect of the present disclosure, the resin composition is such that, in any one of the first to seventh aspects, the content of the polyphenylene ether compound (A) is 20% by mass or more and 90% by mass or less, relative to the total amount of resin components of the resin composition.

[0214] The resin composition according to the ninth aspect of this disclosure has a dielectric loss tangent of less than 0.0040 at 10 GHz in any one of the first to eighth aspects.

[0215] A prepreg (1) according to the tenth aspect of the present disclosure comprises a resin composition or a semi-cured product of a resin composition according to any one of the first to ninth aspects, and a fibrous substrate (12).

[0216] A resin-coated film (2) according to the eleventh aspect of the present disclosure comprises a resin layer (21) containing a resin composition or a semi-cured product of a resin composition according to any one of the first to ninth aspects, and a support film (22).

[0217] A resin-coated metal foil (3) according to a twelfth aspect of the present disclosure comprises a resin layer (31) containing a resin composition or a semi-cured product of a resin composition according to any one of the first to ninth aspects, and a metal foil (32).

[0218] A metal-clad laminate (4) according to the thirteenth aspect of the present disclosure comprises an insulating layer (41) containing a cured resin composition according to any one of the first to ninth aspects, and a metal foil (42).

[0219] A metal-clad laminate (4) according to a fourteenth aspect of the present disclosure comprises an insulating layer (41) containing a cured product of the prepreg (1) according to the tenth aspect, and a metal foil (42).

[0220] A wiring board (5) according to a 15th aspect of the present disclosure comprises an insulating layer (51) containing a cured product of a resin composition according to any one of the first to ninth aspects, and wiring (52).

[0221] A wiring board (5) according to the sixteenth aspect of this disclosure comprises an insulating layer (51) containing a cured prepreg (1) according to the tenth aspect, and wiring (52).

[0222] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0223] (1) Preparation of Resin Compositions The components shown in Table 1 were used as raw materials for the resin compositions. Note that the blending amounts listed in Table 1 represent the mass parts of the solid content of the components excluding solvents, etc. That is, for solvent-dissolved products of the components listed below, the mass of the solvent is not included in the blending amount. Then, a base varnish was prepared by mixing a polyphenylene ether compound (A), a maleimide compound (B), and a solvent (methyl ethyl ketone) to a solid content concentration of 40%, and stirring at 60°C for one hour to homogenize it. To the prepared base varnish, a free radical compound (C) and an inorganic filler (D) were added in the blending amounts shown in Table 1, diluted with a solvent (methyl ethyl ketone), and then stirred and mixed to homogenize it, thereby preparing the resin compositions in the varnish state of the Examples and Comparative Examples, each with a solid content concentration of 60%. Details of each component used are as follows.

[0224] <Polyphenylene ether compound (A)> - Polyphenylene ether #1: Manufactured by Mitsubishi Gas Chemical Co., Ltd., catalog number "OPE-2St-1200", a polyphenylene ether compound having a carbon-carbon unsaturated group in which the terminal hydroxyl group of the polyphenylene ether compound is terminally modified with a vinyl benzyl group (represented by formula (20), in formula (20) R１ ~R ３ A compound in which is a hydrogen atom, Z is a phenylene group, and a is 1), number average molecular weight 1200 - Polyphenylene ether #2: Manufactured by Mitsubishi Gas Chemical Company, Inc., product number "OPE-2St-2200", a polyphenylene ether compound having a carbon-carbon unsaturated group in which the terminal hydroxyl group of the polyphenylene ether compound is terminally modified with a vinyl benzyl group (represented by formula (20), in formula (20) R １ ~R ３ A compound in which ( is a hydrogen atom, Z is a phenylene group, and a is 1), has a number-average molecular weight of 2200.

[0225] <Maleimide Compounds (B)> - Maleimide Compound #1: Manufactured by K.I. Chemicals Co., Ltd., Catalog No. "BMI-80", Compound Name "2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane", Functional Group Equivalent: 285 g / eq., Aromatic Maleimide Compound - Maleimide Compound #2: Manufactured by Nippon Kayaku Co., Ltd., Catalog No. "MIR-5000-60T", Functional Group Equivalent: 260 g / eq., Toluene solution of the aromatic maleimide compound represented by formula (24) - Maleimide Compound #3: Manufactured by Yamato Chemical Industries, Ltd., Catalog No. "BMI-5100", Compound Name "3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide", Functional Group Equivalent: 220 g / eq. Aromatic maleimide compound - Maleimide compound #4: Manufactured by DESIGNER MOLECULES, Inc., catalog number "BMI-689", functional group equivalent: 345 g / eq., an aliphatic maleimide compound represented by formula (25).

[0226] <Free radical compound (C)> - Free radical compound #1: Manufactured by ADEKA Corporation, product number "ADEKA Stab LA-7RD", compound name "4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl free radical", represented by formula (5), where X Ａ A compound in which the group is a hydroxyl group, with a molecular weight of 172.

[0227] <Inorganic Filler (D)> - Inorganic Filler #1: Manufactured by Admatex Co., Ltd., part number "SC2500-SQ", silica.

[0228] <Phenol Compounds> -Phenol compound #1: Manufactured by Yokkaichi Synthetic Co., Ltd., product number "DA-BPA", compound name "2,2'-diallylbisphenol A", allylphenol resin.

[0229] (2) Preparation of evaluation substrates <Prepreg preparation> The varnished resin composition obtained by the method described above was impregnated into a fibrous substrate (glass cloth: #1078 type, NE glass manufactured by Nitto Boseki Co., Ltd.). Next, the resin composition impregnated into the glass cloth was heated and dried at 120°C to 150°C for 3 minutes until it became a semi-cured product. This removed the solvent from the resin composition and produced a prepreg comprising glass cloth and a semi-cured resin composition impregnated into the glass cloth. At that time, the thickness of one prepreg sheet after curing was adjusted to 0.075 mm.

[0230] <Preparation of Metal-Clad Laminates> Ten sheets of the prepreg obtained by the method described above were stacked, and thin copper foil with a carrier copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product number "MT18GN", thickness of thin copper foil: 1.5 μm, thickness of carrier copper foil: 18 μm) was placed on both outer surfaces. This laminate of prepreg and thin copper foil with carrier copper foil was heated and pressurized under vacuum conditions at a temperature of 210°C and a pressure of 4 MPa for 120 minutes. After that, the carrier copper foil of each of the thin copper foils with carrier copper foil placed on both outer surfaces was peeled off to obtain a metal-clad laminate with a thickness of 0.75 mm, comprising an insulating layer containing the cured prepreg and metal layers containing thin copper foil on both sides of this insulating layer.

[0231] (3) Evaluation <Water absorption rate> The copper foil on both sides of the metal-clad laminate obtained by the method described above was removed by etching to obtain an unclad plate. Next, the water absorption rate of this unclad plate was measured according to IPC-TM-6502.6.2.1.

[0232] <Dielectric Loss Tangent (Df)> The copper foil on both sides of the metal-clad laminate obtained by the method described above was removed by etching to obtain an unclad plate. This unclad plate was cut to a width of 2 mm and a length of 100 mm to serve as a test specimen. The dielectric loss tangent Df of this test specimen at 25°C and 10 GHz was measured using a network analyzer (N5230A manufactured by Keysight Technologies, Inc.) by the cavity resonator perturbation method. For evaluation under normal conditions, the test specimen was dried in a constant temperature bath maintained at 105°C for 2 hours, then cooled in a desiccator before measurement. For evaluation after water absorption treatment, the test specimen was subjected to the same water absorption treatment as described above before measurement.

[0233] <Circuit Filling Properties> Conductor wiring in a grid pattern was formed on the copper foil layers on both sides of a copper-clad laminate (manufactured by Panasonic Industries, Ltd., product number "R-5775", thickness 0.2 mm, copper foil 35 μm) so that the residual copper ratio was 50%. One sheet of the prepreg obtained by the method described above was laminated on each side of this copper-clad laminate. Next, a 12 μm thick copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product number "3EC-VLP") was placed on the prepreg and heated and pressurized at a temperature of 210°C and a pressure of 4 MPa for 120 minutes to obtain a laminate. The copper foil carrier on the outer layer of this laminate was peeled off, and the copper foil was further etched across the entire surface to obtain an evaluation sample. The presence or absence of voids between the circuits of the conductor wiring in the obtained evaluation sample was visually confirmed, and the results were evaluated according to the classification below.

[0234] A: The resin composition derived from the prepreg was sufficiently embedded between the circuits of the conductor wiring, and no voids were observed. B: The resin composition derived from the prepreg was insufficiently embedded between the circuits of the conductor wiring, and voids were observed in some patterns.

[0235] <Resin Flow> The prepreg obtained by the method described above was cut into 100±1 mm × 100±1 mm pieces to obtain test specimens. Four of these test specimens were weighed, and the value to the first decimal place of the weighing result was taken as A (g). The laminate was placed in the center of a folded release paper, then sandwiched between release films, and further sandwiched between iron plates, and then subjected to an automatic temperature-controlled press (flow tester) at a temperature of 171±2°C and a pressure of 14±0.3 kg / cm².２ The material was hot-pressed for 15 minutes under the specified conditions. Next, a disc with a diameter of 81.1 ± 0.05 mm was punched out from the center of the laminate, and this disc was weighed using an electronic balance. The value of this weighing result, rounded to one decimal place, was defined as B (g). The resin flow was then calculated using the following formula, and the value obtained by rounding the calculated value to one decimal place was defined as the evaluation value.

[0236] Resin flow (%) = (A × 1.03 - 2 × B) / (A × 1.03) × 100.

[0237] <Metal Peel Strength> First, the carrier copper foil was peeled off both sides of the metal-clad laminate obtained by the method described above. Next, electrolytic copper plating was applied to the thin copper foil on the surface. At that time, the thickness of the metal layer including the electrolytic copper plating and the thin copper foil was adjusted to 35 μm. The substrate after electrolytic copper plating was cut to obtain a test piece measuring 100 mm x 10 mm. For this test piece, the copper foil of the test piece was peeled off at a speed of 50 mm / min using a tensile testing machine in accordance with JIS C6481 (1996), and the metal peel strength was measured.

[0238] <Laser Processability> Surface roughening treatment was performed on the copper foil layers on both sides of a copper-clad laminate (manufactured by Panasonic Industries, Ltd., product number "R-5775", thickness 0.2 mm, copper foil 35 μm) using a micro-etching agent (manufactured by MEC Corporation, "CZ8401"). One prepreg obtained by the above method was laminated on each side of this copper-clad laminate. Next, a thin copper foil with a carrier copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product number "MT18GN", thin copper foil thickness: 1.5 μm, carrier copper foil thickness: 18 μm) was placed on the prepreg, and the laminate was heated and pressurized at a temperature of 210°C and a pressure of 4 MPa for 120 minutes to obtain a laminate, which was used as the evaluation substrate. The carrier copper foil was peeled off the thin copper foil with a carrier copper foil placed on the surface of this evaluation substrate to expose the thin copper foil. On the surface of this thin copper foil, a carbon dioxide laser (Mitsubishi Electric Corporation, part number "ML605GTWV-P") was used to laser process the surface under the following conditions: 2 shots, mask diameter 1.5 mm, energy 5.0 mJ, first shot pulse 12 μs, second shot pulse 4 μs. This process created a total of 2601 via holes, arranged in a 51x51 grid, with a via hole pitch of 105 μm. The via holes and their surroundings formed on the evaluation substrate were then observed, and the results were evaluated according to the classification below.

[0239] A: 2601 via holes with a diameter of 65-70 μm were formed, and no delamination of the copper foil was observed between these via holes. B: 2601 via holes with a diameter of 65-85 μm were formed, and delamination of the copper foil was observed at one or more locations between these via holes.

[0240]

[0241] 1. Prepreg 2. Resin-coated film 3. Resin-coated metal foil 4. Metal-clad laminate 5. Wiring board

Claims

A polyphenylene ether compound (A) having a carbon-carbon unsaturated double bond, Maleimide compound (B) having a functional group equivalent of 230 g / eq. to 500 g / eq., A free radical compound (C) having a molecular weight of 160 or more and 800 or less, and having at least one selected from the group consisting of groups represented by formulas (1), (2), (3), and (4), Inorganic filler (D), A resin composition containing, The aforementioned resin composition does not contain a phenol compound, or The resin composition contains the phenol compound, and the content of the phenol compound is 0.01% by mass or less relative to the total amount of solids in the resin composition. Resin composition. The maleimide compound (B) comprises an aromatic maleimide compound (B1) having a phenylmaleimide group. The resin composition according to claim 1. 　 The maleimide compound (B) comprises an aliphatic maleimide compound (B2). The resin composition according to claim 1. 　 The free radical compound (C) comprises at least one selected from the group consisting of compounds represented by formulas (5), (6), and (7), In formula (5), X Ａ This exhibits an ether bond with an amino group, cyano group, hydroxyl group, isothiocyanate group, carboxyl group, oxo group, amide group, acyloxy group, or organic group. In formula (6), X Ｂ This exhibits an ether bond with a cyano group, isothiocyanate group, carboxyl group, amide group, acyloxy group, or organic group. In formula (7), X Ｃ This represents an alkylene group, an aromatic structure, a carbonyl group, an amide group, or an oxygen atom. The resin composition according to claim 1. 　 The content of the free radical compound (C) is 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B). The resin composition according to claim 1. 　 The amount of the inorganic filler (D) is 10 parts by mass or more and 250 parts by mass or less, relative to 100 parts by mass of the total of the polyphenylene ether compound (A) and the maleimide compound (B). The resin composition according to claim 1. 　 The polyphenylene ether compound (A) has at least one selected from the group consisting of groups represented by formula (8) and formula (9), In formula (8), a represents an integer between 0 and 10, Z represents an arylene group, and R １ ~R ３ Each of these independently represents a hydrogen atom or an alkyl group. In formula (9), R ４ This represents a hydrogen atom or an alkyl group. The resin composition according to claim 1. 　 The content of the polyphenylene ether compound (A) is 20% by mass or more and 90% by mass or less relative to the total amount of resin components in the resin composition. The resin composition according to claim 1. 　 The dielectric loss tangent of the cured material at 10 GHz is less than 0.0040. The resin composition according to claim 1. 　 A resin composition according to any one of claims 1 to 9 or a semi-cured product of the resin composition, and a fibrous substrate, Prepreg. 　 A resin layer comprising a resin composition according to any one of claims 1 to 9 or a semi-cured product of the resin composition, and a support film, Resin-coated film. 　 A resin layer comprising a resin composition according to any one of claims 1 to 9 or a semi-cured product of the resin composition, and a metal foil, Metal foil coated with resin. The insulating layer comprises a cured resin composition according to any one of claims 1 to 9, and a metal foil. Metal-clad laminate. 　 The insulating layer comprises a cured prepreg according to claim 10 and a metal foil, Metal-clad laminate. 　 The system comprises an insulating layer containing a cured resin composition according to any one of claims 1 to 9, and wiring, wiring board. 　 The system comprises an insulating layer containing a cured prepreg according to claim 10, and wiring, wiring board.

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