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

Abstract

One aspect of the present invention is a resin composition comprising an indane-skeleton-containing (meth)acrylate compound (A) represented by general formula (1), a crosslinking type hardener (B) having a molecular weight less than 400 and having two or more unsaturated double bonds in the molecule, and an inorganic filler (C). In formula (1), X represents a (meth)acryloyloxy group, Ra and Rb each independently represent a C1-C12 alkyl, aryl, aralkyl or cycloalkyl group, j indicates an integer of 1-3, k and l each independently indicate an integer of 0-4, n indicates the average number of repeating units and is a number of 0.5-20, and m indicates an integer of 0-2.

Description

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

[0001] The present invention relates to a resin composition, a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board.

[0002] With the increase in the amount of information processed and the increase in the speed of information communication, various electronic devices are undergoing advances in packaging technologies, such as higher integration of semiconductor devices, higher density wiring, and multi-layering. Furthermore, wiring boards used in various electronic devices are required to be high-frequency compatible, such as server boards for communication infrastructure equipment applications such as network equipment, servers, and AI (artificial intelligence) processors, and millimeter-wave radar boards for in-vehicle applications. Substrate materials for constituting the insulating layers of wiring boards used in various electronic devices are required to have excellent low-dielectric properties, such as low relative permittivity and dielectric loss tangent, in order to increase signal transmission speeds and reduce loss during signal transmission.

[0003] Examples of substrate materials for forming the insulating layer of such wiring boards include resin compositions described in Patent Documents 1 and 2.

[0004] Patent Document 1 describes a curable poly(ethylene ether) composition containing a polyethylene ether containing a hydroxyl group blocked with an ethylenically unsaturated compound and a curable unsaturated monomer composition. Patent Document 1 discloses that it is possible to provide a thermosetting composition for use in printed circuit boards and the like, which has excellent dielectric properties, thermal properties, solvent resistance, and a low coefficient of thermal expansion.

[0005] Patent Document 2 describes a resin composition containing a modified polyphenylene ether compound terminally modified with a substituent having a carbon-carbon unsaturated double bond, a cross-linking curing agent having a carbon-carbon unsaturated double bond in the molecule, and a flame retardant containing a compatible phosphorus compound and an incompatible phosphorus compound. Patent Document 2 discloses that it is possible to provide a resin composition that exhibits excellent heat resistance and flame retardancy of a cured product while maintaining the excellent dielectric properties of polyphenylene ether.

[0006] Substrate materials for forming the insulating layer of wiring boards are required to not only have excellent low dielectric properties such as a low relative dielectric constant, but also to sufficiently suppress the increase in dielectric loss tangent due to water absorption, and to produce a cured product with a low coefficient of thermal expansion.

[0007] US Patent Application Publication No. 2001 / 0053450 JP 2015-86330 A

[0008] The present invention has been made in view of the above circumstances, and aims to provide a resin composition that has excellent low dielectric properties such as a low relative permittivity, sufficiently suppresses an increase in dielectric loss tangent due to water absorption, and further provides a cured product with a low coefficient of thermal expansion. Another aim of the present invention is to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that are obtained using the resin composition.

[0009] One aspect of the present invention is a resin composition comprising: (A) a (meth)acrylate compound having an indane skeleton represented by the following general formula (1); (B) a cross-linking curing agent having a molecular weight of less than 400 and having two or more unsaturated double bonds in the molecule; and (C) an inorganic filler.

[0010] In the above formula (1), X represents a (meth)acryloyloxy group; Ra and Rb each independently represent an alkyl group, aryl group, aralkyl group, or cycloalkyl group having 1 to 12 carbon atoms; j represents an integer of 1 to 3; k and l each independently represent an integer of 0 to 4; n is an average repeating unit and represents a number of 0.5 to 20; and m represents an integer of 0 to 2.

[0011] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0012] Fig. 1 is a schematic cross-sectional view showing an example of a prepreg according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a metal-clad laminate according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of a wiring board according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing an example of a resin-coated metal foil according to an embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing an example of a resin-coated film according to an embodiment of the present invention.

[0013] Electronic devices, particularly small portable devices such as mobile communication terminals and notebook PCs, are rapidly becoming more multifunctional, high-performance, thin, and compact. Accordingly, wiring boards used in these products are also required to have finer conductor wiring, more multilayered conductor wiring layers, thinner designs, and improved mechanical properties. In particular, as wiring boards become thinner and larger, warping occurs in semiconductor packages mounting semiconductor chips on the wiring board, which increases the likelihood of mounting defects. To suppress warping in semiconductor packages mounting semiconductor chips on wiring boards, the insulating layer is required to have a low thermal expansion coefficient (thermal expansion rate). Therefore, substrate materials for forming the insulating layer of wiring boards are required to produce cured products with a low thermal expansion rate.

[0014] Wiring boards and the like used in various electronic devices are also required to be resistant to the effects of changes in the external environment, etc. For example, so that the wiring board can be used even in a humid environment, the insulating layer of the wiring board is required to have a dielectric loss tangent that varies little with humidity changes. Therefore, the substrate material constituting the insulating layer of the wiring board is required to provide a cured product that has a dielectric loss tangent that varies little with humidity changes, and for example, it is required to provide a cured product in which the increase in dielectric loss tangent is sufficiently suppressed even when the wiring board absorbs water.

[0015] As a result of extensive investigations, the present inventors have found that the above-mentioned object of providing a resin composition which has excellent low dielectric properties such as a low relative dielectric constant, in which an increase in dielectric loss tangent due to water absorption is sufficiently suppressed, and which gives a cured product with a low thermal expansion coefficient can be achieved by the present invention described below.

[0016] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these.

[0017] [Resin Composition] A resin composition according to an embodiment of the present invention is a resin composition comprising (A) a (meth)acrylate compound having an indane skeleton represented by the following general formula (1), (B) a cross-linking curing agent having a molecular weight of less than 400 and two or more unsaturated double bonds in the molecule, and (C) an inorganic filler. By curing the resin composition, a cured product having excellent low dielectric properties such as a low relative permittivity, sufficient suppression of an increase in dielectric loss tangent due to water absorption, and a low coefficient of thermal expansion can be obtained.

[0018] ((Meth)acrylate Compound (A)) The (meth)acrylate compound (A) is not particularly limited as long as it is a (meth)acrylate compound having an indane skeleton represented by the following general formula (1).

[0019] In the above formula (1), X represents a (meth)acryloyloxy group. Ra and Rb each independently represent an alkyl group, aryl group, aralkyl group, or cycloalkyl group having 1 to 12 carbon atoms. j represents an integer of 1 to 3. k and l each independently represent an integer of 0 to 4. n is an average repeating unit and represents a number of 0.5 to 20. m represents an integer of 0 to 2. The straight lines from each of Ra, X, and the carbon atom to the aromatic ring indicate that Ra, X, and the carbon atom may each be bonded to any carbon atom of the aromatic ring.

[0020] The (meth)acrylate compound (A) has a low-polarity indane skeleton, which reduces the proportion of polar functional groups in the structure of the (meth)acrylate compound (A). As a result, a cured product produced using the (meth)acrylate compound (A) has excellent low dielectric properties. For this reason, it is preferable to include the (meth)acrylate compound (A) in the resin composition. Furthermore, the (meth)acrylate compound (A) is preferable because it has the indane skeleton, which provides excellent flexibility and pliability and is expected to improve brittleness resistance.

[0021] In the above formula (1), X is a (meth)acryloyloxy group, that is, an acryloyloxy group or a methacryloyloxy group, and preferably a methacryloyloxy group. X is a crosslinking group. The (meth)acrylate compound (A) is preferred because it has a (meth)acryloyloxy group in it, and thus a cured product having a low dielectric tangent can be obtained compared to compounds having other crosslinking groups [e.g., vinylbenzyl ether groups (styryl groups), dihydroxybenzene groups, etc.].

[0022] Although the detailed reason why the (meth)acrylate compound (A) containing the (meth)acryloyloxy group results in a cured product exhibiting low dielectric properties is unclear, it is speculated that the low molecular mobility of the ester group based on the (meth)acryloyloxy group contributes to this. For example, a curable compound containing a vinylbenzyl ether group (styryl group) as a conventionally used curable compound will have an ether group, which is a polar group. Furthermore, a curable compound containing a dihydroxybenzene group will have multiple hydroxyl groups, which are polar groups. The ester group based on the (meth)acryloyloxy group has lower molecular mobility than the polar groups of conventionally used curable compounds. Therefore, it is speculated that the lower molecular mobility of the ester group based on the (meth)acryloyloxy group contributes to this. The presence of a highly polar polar group, such as an ether group or a hydroxyl group, tends to increase the relative dielectric constant and dielectric loss tangent.

[0023] When the crosslinking group X is a methacryloyloxy group, a cured product with a lower dielectric loss tangent can be obtained, which is preferable. The reason why a cured product with a lower dielectric loss tangent can be obtained when the crosslinking group X is a methacryloyloxy group is presumably because the methacryloyloxy group contains a methyl group in its structure, which increases steric hindrance and further reduces molecular mobility. Furthermore, when there are multiple crosslinking groups, the crosslinking density increases and heat resistance improves.

[0024] In the above formula (1), each Ra independently represents an alkyl group, aryl group, aralkyl group, or cycloalkyl group having 1 to 12 carbon atoms, and is preferably an alkyl group, aryl group, or cycloalkyl group having 1 to 4 carbon atoms. The (meth)acrylate compound (A) is preferably such a group as an alkyl group having 1 to 12 carbon atoms, because the planarity near any of the benzene ring, naphthalene ring, and anthracene ring, as described below, is reduced, and the reduced crystallinity improves solvent solubility and lowers the melting point. Furthermore, the (meth)acrylate compound (A) is preferably such a group because the Ra acts as a steric hindrance, further reducing molecular mobility, thereby enabling a cured product with a lower dielectric tangent to be obtained.

[0025] In the formula (1), each Rb independently represents an alkyl group, aryl group, aralkyl group, or cycloalkyl group having 1 to 12 carbon atoms, and is preferably an alkyl group, aryl group, or cycloalkyl group having 1 to 4 carbon atoms. In the (meth)acrylate compound (A), when Rb is the group such as an alkyl group having 1 to 12 carbon atoms, the planarity in the vicinity of any one of a benzene ring, a naphthalene ring, and an anthracene ring, which will be described later, is reduced, and the reduced crystallinity improves solvent solubility and lowers the melting point, which is preferable.

[0026] In the above formula (1), j represents an integer of 1 to 3, preferably an integer of 1 to 2. It is preferable that j is within the above range, since the flexibility of the (meth)acrylate compound (A) is ensured. Note that it is preferable that a plurality of Xs serving as crosslinking groups are introduced into the same benzene ring or the like, since the plurality of crosslinking groups inhibit (suppress) each other's molecular mobility, and a cured product exhibiting a low dielectric tangent can be obtained even in the absence of the substituent Ra.

[0027] In the formula (1), k and l each independently represent an integer of 0 to 4, and preferably an integer of 0 to 2. It is preferable that each of k and l is within the above range, since the reactivity of the (meth)acrylate compound (A) is excellent.

[0028] In the above formula (1), m represents an integer of 0 to 2. Specifically, in the (meth)acrylate compound (A), the aromatic ring in parentheses with m is a benzene ring when m is 0, a naphthalene ring when m is 1, and an anthracene ring when m is 2, and is preferably a benzene ring with m being 0. It is preferable that m is within the above range from the viewpoint of improving the solvent solubility of the (meth)acrylate compound (A).

[0029] In the above formula (1), n ​​represents the average number of repeating units and is a value between 0.5 and 20, preferably between 0.5 and 5, and more preferably between 0.95 and 2.5. It is preferable that n is within the above range (that the indane skeleton is present within the above range) because this improves the solvent solubility of the (meth)acrylate compound (A). If n is less than 0.5, the proportion of high-melting-point substances in the structure of the (meth)acrylate compound having an indane skeleton will be high, resulting in poor solvent solubility. Furthermore, the proportion of high-molecular-weight components that contribute to flexibility will be low, resulting in poor brittle resistance of the resulting cured product. Furthermore, flexibility and pliability may also be reduced. For these reasons, it is not preferable for n to be less than 0.5. Furthermore, if n exceeds 20, the viscosity of the (meth)acrylate compound having an indane skeleton will increase when dissolved in a solvent. Furthermore, there is a concern that the heat resistance of the resulting cured product will be poor. Furthermore, there is a concern that the amount of high molecular weight components will be too high, resulting in reduced fluidity and poor handleability when molding the cured product. For these reasons, it is not preferable for n to exceed 20. Furthermore, from the viewpoint of a high heat distortion temperature, a high glass transition temperature, etc. of the cured product, the value of n is particularly preferably 0.95 to 2.5.

[0030] The (meth)acrylate compound (A) has the indane skeleton, which introduces an alicyclic structure into the structure of the (meth)acrylate compound, which has an excellent balance between heat resistance and dielectric properties. Therefore, a cured product produced using the (meth)acrylate compound (A) has an excellent balance between heat resistance and dielectric properties (particularly a low dielectric tangent), and further has a (meth)acryloyloxy group, which serves as a crosslinking group, in the molecular structure, which allows it to exhibit even lower dielectric properties, which is preferable.

[0031] Examples of the (meth)acrylate compound (A) include a (meth)acrylate compound (a) having an indane skeleton represented by the following general formula (2): The (meth)acrylate compound (A) preferably contains the (meth)acrylate compound (a).

[0032] In the above formula (2), R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and R １ and R ２ are not simultaneously hydrogen atoms, and n is the average repeating unit and is a value of 0.5 to 20.

[0033] In the above formula (2), R １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and are not both hydrogen atoms at the same time, and are preferably an alkyl group, an aryl group, or a cycloalkyl group having 1 to 4 carbon atoms. １ and R ２ are the above-mentioned groups such as alkyl groups having 1 to 12 carbon atoms, the planarity in the vicinity of the benzene ring is reduced, and the reduced crystallinity improves the solvent solubility and lowers the melting point, which is preferable. １ and the R ２ and R １ and the R２ Since both of these groups cannot be hydrogen atoms at the same time, it is presumed that steric hindrance increases and molecular mobility further decreases, which is preferable because it is possible to obtain a cured product with a lower dielectric loss tangent.

[0034] In the above formula (2), n represents the average number of repeating units and is a value between 0.5 and 20, preferably between 0.5 and 5, and more preferably between 0.95 and 2.5. It is preferable that n is within the above range (that the indane skeleton is present within the above range) because this improves the solvent solubility of the (meth)acrylate compound (a). If n is less than 0.5, the proportion of high-melting-point substances in the structure of the (meth)acrylate compound having an indane skeleton will be high, resulting in poor solvent solubility. Furthermore, the proportion of high-molecular-weight components that contribute to flexibility will be low, resulting in poor brittle resistance of the resulting cured product. Furthermore, flexibility and pliability may also be reduced. For these reasons, it is not preferable for n to be less than 0.5. Furthermore, if n exceeds 20, the viscosity of the (meth)acrylate compound having an indane skeleton will increase when dissolved in a solvent. Furthermore, there is a concern that the heat resistance of the resulting cured product will be poor. Furthermore, there is a concern that the amount of high molecular weight components will be too high, resulting in reduced fluidity and poor handleability when molding the cured product. For these reasons, it is not preferable for n to exceed 20. Furthermore, from the viewpoint of achieving a high heat distortion temperature and a high glass transition temperature of the cured product, the value of n is particularly preferably 0.95 to 2.5.

[0035] The (meth)acrylate compound (a) has the indane skeleton, which introduces an alicyclic structure into the structure of the (meth)acrylate compound (a), which exhibits an excellent balance between heat resistance and dielectric properties. A cured product produced using the (meth)acrylate compound (a) exhibits an excellent balance between heat resistance and dielectric properties (particularly a low dielectric tangent), and the presence of a methacryloyloxy group at the end of the molecular structure increases steric hindrance compared to an acryloyloxy group, thereby enabling the development of even lower dielectric properties, which is preferable.

[0036] (Crosslinking Curing Agent (B)) The crosslinking curing agent (B) is not particularly limited as long as it has a molecular weight of less than 400 and has two or more unsaturated double bonds in the molecule. Examples of the crosslinking curing agent (B) include a compound that is different from the (meth)acrylate compound (A) and can react with the (meth)acrylate compound (A) to cure the resin composition. Examples of the crosslinking curing agent (B) include allyl compounds, vinyl compounds, maleimide compounds, and (meth)acrylate compounds (b) other than the (meth)acrylate compound (A).

[0037] The allyl compound is a compound having an allyl group in the molecule, and examples of the allyl compound include compounds having an allyl group and an isocyanurate group in the molecule, such as triallyl isocyanurate (TAIC), diallyl bisphenol compounds, and diallyl phthalate (DAP).

[0038] The vinyl compound is a compound having a vinyl group in its molecule. Examples of the vinyl compound include monofunctional vinyl compounds having one vinyl group in its molecule and polyfunctional vinyl compounds having two or more vinyl groups in its molecule. Examples of the monofunctional vinyl compound include vinylbenzene compounds having a phosphorus atom-containing skeleton in its molecule, such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Examples of the polyfunctional vinyl compound include divinylbenzene and polybutadiene compounds. Examples of the polybutadiene compound include polybutadiene and hydrogenated styrene-butadiene copolymers, and more specifically, B-1000, B-2000, and B-3000 manufactured by Nippon Soda Co., Ltd., and Ricon manufactured by Cray Valley Chemical Industries, Ltd.

[0039] The maleimide compound is a compound having a maleimide group in the molecule. Examples of the maleimide compound include monofunctional maleimide compounds having one maleimide group in the molecule and polyfunctional maleimide compounds having two or more maleimide groups in the molecule. Examples of the modified maleimide compound include modified maleimide compounds in which a portion of the molecule is amine-modified, modified maleimide compounds in which a portion of the molecule is silicone-modified, and modified maleimide compounds in which a portion of the molecule is both amine-modified and silicone-modified.

[0040] The (meth)acrylate compound (b) is not particularly limited as long as it is a (meth)acrylate compound other than the (meth)acrylate compound (A). The (meth)acrylate compound (b) is a methacrylate compound and an acrylate compound different from the (meth)acrylate compound (A).

[0041] Examples of the methacrylate compound include a monofunctional methacrylate compound having one methacryloyl group in the molecule and a polyfunctional methacrylate compound having two or more methacryloyl groups in the molecule. Examples of the monofunctional methacrylate compound include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Examples of the polyfunctional methacrylate compound include a dimethacrylate compound such as tricyclodecane dimethanol dimethacrylate (DCP).

[0042] Examples of the acrylate compound include a monofunctional acrylate compound having one acryloyl group in the molecule and a polyfunctional acrylate compound having two or more acryloyl groups in the molecule. Examples of the monofunctional acrylate compound include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Examples of the polyfunctional acrylate compound include a diacrylate compound such as tricyclodecane dimethanol diacrylate.

[0043] Among the above, the crosslinking curing agent (B) is preferably, for example, the allyl compound and the methacrylate compound, and more preferably, triallyl isocyanurate (TAIC) and tricyclodecane dimethanol dimethacrylate (DCP). TAIC is preferred because it has excellent low dielectric properties such as a low dielectric constant, sufficiently suppresses the increase in dielectric loss tangent due to water absorption, and provides a cured product with not only a low thermal expansion coefficient but also a high glass transition temperature. DCP is preferred because it provides a cured product that can further suppress the increase in dielectric constant due to water absorption and the increase in dielectric loss tangent due to water absorption. The crosslinking curing agent (B) may be used alone or in combination of two or more of the above crosslinking curing agents.

[0044] The molecular weight of the crosslinking curing agent (B) is less than 400, preferably 100 to less than 400, and more preferably 150 to 300. Using a crosslinking curing agent (B) with such a molecular weight allows for favorable curing of a resin composition containing the (meth)acrylate compound (A). Thus, curing results in a cured product with excellent low dielectric properties, such as a low relative dielectric constant, sufficient suppression of an increase in dielectric loss tangent due to water absorption, and a low coefficient of thermal expansion. Since the crosslinking curing agent (B) is not a polymeric substance, the molecular weight may simply be the molecular weight, but it may also be the weight-average molecular weight (Mw). The weight-average molecular weight (Mw) may be measured using a common molecular weight measurement method, specifically, a value measured using gel permeation chromatography (GPC), etc.

[0045] (Inorganic Filler (C)) The inorganic filler (C) is not particularly limited as long as it is an inorganic filler that can be used as an inorganic filler contained in a resin composition. Examples of the inorganic filler (C) include metal oxide fillers, metal hydroxide fillers, molybdate fillers, nitride fillers, titanate fillers, magnesium carbonate fillers such as anhydrous magnesium carbonate fillers, calcium carbonate fillers, quartz glass fillers, talc fillers, aluminum borate fillers, and barium sulfate fillers. Examples of the metal oxide fillers include silica fillers, alumina fillers, titanium oxide fillers, magnesium oxide fillers, and mica fillers. Examples of the silica fillers include crushed silica, spherical silica such as fused spherical silica, and silica particles. Examples of the metal hydroxide fillers include magnesium hydroxide fillers and aluminum hydroxide fillers. Examples of the molybdate fillers include zinc molybdate fillers, calcium molybdate fillers, and magnesium molybdate fillers. Examples of the nitride filler include aluminum nitride filler and boron nitride filler. Examples of the titanate filler include barium titanate filler, strontium titanate filler, calcium titanate filler, and aluminum titanate filler. Among these, metal hydroxide fillers such as silica filler, magnesium hydroxide filler, and aluminum hydroxide filler, aluminum oxide filler, boron nitride filler, strontium titanate filler, calcium titanate filler, and zinc molybdate filler are preferred, with silica filler being more preferred. The silica filler is not particularly limited, but may be, for example, solid silica particles or hollow silica particles. The inorganic filler may be used alone or in combination of two or more. When two or more inorganic fillers are used in combination, a silica filler may be used in combination with one or more inorganic fillers other than silica filler, and a silica filler and a zinc molybdate filler are preferably used in combination.The inorganic filler may be, for example, a talc filler carrying molybdate, which is one of the molybdate fillers.

[0046] The inorganic filler (C) may be a surface-treated or untreated inorganic filler. Examples of the surface treatment include treatment with a silane coupling agent.

[0047] The silane coupling agent is not particularly limited, and examples thereof include silane coupling agents having at least one functional group selected from the group consisting of vinyl group, styryl group, methacryloyl group, acryloyl group, phenylamino group, isocyanurate group, ureido group, mercapto group, isocyanate group, epoxy group, and acid anhydride group. That is, the silane coupling agent has at least one reactive functional group selected from vinyl group, styryl group, methacryloyl group, acryloyl group, phenylamino group, isocyanurate group, ureido group, mercapto group, isocyanate group, epoxy group, and acid anhydride group, and further includes compounds having a hydrolyzable group such as a methoxy group or an ethoxy group.

[0048] Examples of the silane coupling agent include those having a vinyl group, such as vinyltriethoxysilane and vinyltrimethoxysilane. Examples of the silane coupling agent include those having a styryl group, such as p-styryltrimethoxysilane and p-styryltriethoxysilane. Examples of the silane coupling agent include those having a methacryloyl group, such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylethyldiethoxysilane. Examples of the silane coupling agent include those having an acryloyl group, such as 3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane. Examples of the silane coupling agent include those having a phenylamino group, such as N-phenyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltriethoxysilane.

[0049] The average particle size of the inorganic filler (C) is not particularly limited, and is preferably 0.05 to 10 μm, and more preferably 0.1 to 8 μm. Here, the average particle size refers to the volume average particle size. The volume average particle size can be measured, for example, by a laser diffraction method.

[0050] (Content) The content ratio of the (meth)acrylate compound (A) to the crosslinking curing agent (B) is preferably 90:10 to 50:50, more preferably 90:10 to 60:40, by mass ratio.

[0051] The content of the (meth)acrylate compound (A) is preferably 20 to 90% by mass, and more preferably 30 to 70% by mass, based on the resin composition.

[0052] The content of the crosslinking curing agent (B) is preferably 5 to 40% by mass, and more preferably 5 to 25% by mass, based on the resin composition.

[0053] The content of the inorganic filler (C) is preferably 10 to 70% by mass, more preferably 10 to 50% by mass, relative to the resin composition, and is preferably 10 to 250 parts by mass, more preferably 10 to 150 parts by mass, relative to 100 parts by mass of the organic components (other than the inorganic filler (C) in the resin composition).

[0054] By incorporating the (meth)acrylate compound (A), the cross-linking curing agent (B), and the inorganic filler (C) so that the respective contents fall within the above ranges, the obtained resin composition, when cured, exhibits excellent low dielectric properties such as a low relative dielectric constant, is sufficiently suppressed from increasing the dielectric loss tangent due to water absorption, and further, a cured product having a low thermal expansion coefficient can be suitably obtained.

[0055] (Organic Peroxide (D)) The resin composition may contain an organic peroxide (D) as needed, as long as the effects of the present invention are not impaired. The resin composition preferably contains the organic peroxide (D) from the viewpoint of accelerating the curing reaction of the resin composition and more suitably curing the resin composition. Examples of the organic peroxide (D) include α,α'-di(t-butylperoxy)diisopropylbenzene (PBP), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and benzoyl peroxide, with PBP being preferred.

[0056] When the resin composition contains the organic peroxide (D), the content of the organic peroxide (D) is preferably 0.2 to 10 mass %, more preferably 0.5 to 5 mass %, relative to the organic component.

[0057] (Other Components) The resin composition may contain components (other components) other than the (meth)acrylate compound (A), the cross-linking curing agent (B), and the inorganic filler (C), as long as the effects of the present invention are not impaired. As described above, the resin composition may contain the organic peroxide (D) as the other component. In addition to the organic peroxide (D), examples of the other components include organic components other than the (meth)acrylate compound (A), the cross-linking curing agent (B), and the organic peroxide (D), flame retardants, reaction initiators other than the organic peroxide (D), curing accelerators, catalysts, polymerization retarders, polymerization inhibitors, dispersants, leveling agents, coupling agents, defoamers, antioxidants, heat stabilizers, antistatic agents, UV absorbers, dyes, pigments, and additives such as lubricants.

[0058] As described above, the resin composition according to this embodiment may contain an organic component other than the (meth)acrylate compound (A), the cross-linking curing agent (B), and the organic peroxide (D). The organic component may be, for example, a compound that reacts with at least one of the (meth)acrylate compound (A) and the cross-linking curing agent (B), or a compound that does not react with the (meth)acrylate compound (A). Specific examples of the organic component include styrene-based polymers, oxazine compounds, epoxy compounds, cyanate ester compounds, and active ester compounds.

[0059] The styrene-based polymer is not particularly limited, and examples thereof include styrene-based polymers that can be used as resins contained in resin compositions used to form insulating layers in metal-clad laminates, wiring boards, etc. The resin compositions used to form insulating layers in metal-clad laminates, wiring boards, etc. may be resin compositions used to form resin layers in resin-coated films, resin-coated metal foils, etc., or may be resin compositions contained in prepregs. Examples of the styrene-based polymer include styrene-based copolymers obtained by copolymerizing one or more styrene-containing monomers (styrene-based monomers) with one or more other monomers copolymerizable with the styrene-based monomer. The styrene-based copolymer may be a random copolymer or a block copolymer. Examples of the block copolymer include a binary copolymer of a structural unit (repeating unit) derived from the styrene-based monomer and a structural unit (repeating unit) derived from the other copolymerizable monomer, and a terpolymer of a structure (repeating unit) derived from the styrene-based monomer, a structural unit (repeating unit) derived from the other copolymerizable monomer, and a structural unit (repeating unit) derived from the styrene-based monomer. The styrene-based polymer may be a hydrogenated styrene-based copolymer obtained by hydrogenating the styrene-based copolymer described above, or may be one modified with an acid component such as maleic acid. Examples of the styrene-based polymer may include a styrene-based polymer having an unsaturated double bond in the molecule, and more specifically, a styrene-based polymer containing 60 mol% or more of structural units having a 1,2-vinyl group in the side chain relative to all structural units.

[0060] The oxazine compound is not particularly limited as long as it is a compound having an oxazine group in the molecule. Examples of the oxazine compound include benzoxazine compounds having a phenolphthalein structure in the molecule (phenolphthalein-type benzoxazine compounds), bisphenol F-type benzoxazine compounds, and diaminodiphenylmethane (DDM)-type benzoxazine compounds. More specific examples of the oxazine compound include 3,3'-(methylene-1,4-diphenylene)bis(3,4-dihydro-2H-1,3-benzoxazine) (P-d-type benzoxazine compound) and 2,2-bis(3,4-dihydro-2H-3-phenyl-1,3-benzoxazine)methane (F-a-type benzoxazine compound).

[0061] The epoxy compound is a compound having an epoxy group in the molecule, and specific examples thereof include bisphenol-type epoxy compounds such as bisphenol A-type epoxy compounds, phenol novolac-type epoxy compounds, cresol novolac-type epoxy compounds, dicyclopentadiene-type epoxy compounds, bisphenol A novolac-type epoxy compounds, biphenyl aralkyl-type epoxy compounds, polybutadiene compounds having an epoxy group in the molecule, and naphthalene ring-containing epoxy compounds. The epoxy compound also includes epoxy resins, which are polymers of the above-mentioned epoxy compounds.

[0062] The cyanate ester compound is a compound having a cyanate group in the molecule, and examples thereof include 2,2-bis(4-cyanatephenyl)propane, bis(3,5-dimethyl-4-cyanatephenyl)methane, and 2,2-bis(4-cyanatephenyl)ethane.

[0063] The active ester compound is a compound having an ester group with high reactivity in the molecule, and examples thereof include benzenecarboxylic acid active ester, benzenedicarboxylic acid active ester, benzenetricarboxylic acid active ester, benzenetetracarboxylic acid active ester, naphthalenecarboxylic acid active ester, naphthalenedicarboxylic acid active ester, naphthalenetricarboxylic acid active ester, naphthalenetetracarboxylic acid active ester, fluorenecarboxylic acid active ester, fluorenedicarboxylic acid active ester, fluorenetricarboxylic acid active ester, and fluorenetetracarboxylic acid active ester.

[0064] As described above, the resin composition according to this embodiment may contain a flame retardant. By including a flame retardant, the flame retardancy of the cured resin composition can be improved. The flame retardant is not particularly limited. Specifically, in fields where halogen-based flame retardants such as bromine-based flame retardants are used, for example, ethylene dipentabromobenzene, ethylene bistetrabromoimide, decabromodiphenyl oxide, tetradecabromodiphenoxybenzene, and bromostyrene-based compounds that react with the polymerizable compounds, which have melting points of 300°C or higher, are preferred. It is believed that the use of a halogen-based flame retardant can suppress halogen elimination at high temperatures and thus suppress a decrease in heat resistance. Furthermore, in fields where halogen-free materials are required, phosphorus-containing flame retardants (phosphorus-based flame retardants) are sometimes used. The phosphorus-based flame retardant is not particularly limited, but examples thereof include phosphate ester-based flame retardants, phosphazene-based flame retardants, bisdiphenylphosphine oxide-based flame retardants, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardants, and phosphinate-based flame retardants. Specific examples of phosphate ester-based flame retardants include condensed phosphate esters of dixylenyl phosphate. Specific examples of phosphazene-based flame retardants include phenoxyphosphazene. Specific examples of bisdiphenylphosphine oxide-based flame retardants include xylylenebisdiphenylphosphine oxide. Specific examples of DOPO-based flame retardants include hydrocarbons having two DOPO groups in the molecule (DOPO derivative compounds) and DOPO having a reactive functional group. Specific examples of phosphinate-based flame retardants include metal phosphinates of aluminum dialkylphosphinates. As the flame retardant, each of the exemplified flame retardants may be used alone or in combination of two or more kinds.

[0065] As described above, the resin composition according to this embodiment may contain a reaction initiator other than the organic peroxide (D). The reaction initiator other than the organic peroxide (D) is not particularly limited as long as it can accelerate the curing reaction of the resin composition, and examples thereof include organic azo compounds. Examples of the organic azo compounds include azobisisobutyronitrile. Furthermore, if necessary, a metal carboxylate or the like can be used in combination. This can further accelerate the curing reaction. The reaction initiator other than the organic peroxide (D) may be used alone or in combination of two or more.

[0066] As described above, the resin composition according to this embodiment may contain a curing accelerator. The curing accelerator is not particularly limited as long as it can accelerate the curing reaction of the resin composition. Specific examples of the curing accelerator include imidazoles and their derivatives, organophosphorus compounds, amines such as secondary amines and tertiary amines, quaternary ammonium salts, organoboron compounds, and metal soaps. Examples of the imidazoles include 2-ethyl-4-methylimidazole (2E4MZ), 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, and 1-benzyl-2-methylimidazole. Examples of the organophosphorus compounds include triphenylphosphine, diphenylphosphine, phenylphosphine, tributylphosphine, and trimethylphosphine. Examples of the amines include dimethylbenzylamine, triethylenediamine, triethanolamine, and 1,8-diaza-bicyclo(5,4,0)undecene-7 (DBU). Examples of the quaternary ammonium salts include tetrabutylammonium bromide. Examples of the organoboron compounds include tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate, and tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium ethyltriphenylborate. The metal soap refers to a fatty acid metal salt, and may be either a linear fatty acid metal salt or a cyclic fatty acid metal salt. Specific examples of the metal soap include linear fatty acid metal salts and cyclic fatty acid metal salts having 6 to 10 carbon atoms. More specifically, examples of the curing accelerator include aliphatic metal salts composed of linear fatty acids such as stearic acid, lauric acid, ricinoleic acid, and octylic acid, or cyclic fatty acids such as naphthenic acid, and metals such as lithium, magnesium, calcium, barium, copper, and zinc. For example, zinc octylate is included. The curing accelerators may be used alone or in combination of two or more.

[0067] As described above, the resin composition according to this embodiment may contain a silane coupling agent. The silane coupling agent may be contained in the resin composition, or may be contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler contained in the resin composition. Among these, the silane coupling agent is preferably contained as a silane coupling agent that has been surface-treated in advance on an inorganic filler, and it is more preferable to contain the silane coupling agent in advance on an inorganic filler in this way, and further to contain the silane coupling agent in the resin composition. In addition, in the case of a prepreg, the prepreg may contain the silane coupling agent that has been surface-treated in advance on a fibrous substrate. Examples of the silane coupling agent include the same silane coupling agents as those used when surface-treating the inorganic filler described above.

[0068] The resin composition according to the present embodiment has excellent low dielectric properties such as a low relative permittivity, is sufficiently suppressed from increasing in dielectric loss tangent due to water absorption, and provides a cured product with a low coefficient of thermal expansion. For this reason, wiring boards having an insulating layer formed using the resin composition according to the present embodiment are less likely to warp.

[0069] (Uses) The resin composition is used to produce a prepreg, as described below, and to form a resin layer provided in a resin-coated metal foil or a resin-coated film, and an insulating layer provided in a metal-clad laminate or a wiring board.

[0070] (Production Method) The method for producing the resin composition is not particularly limited, and examples thereof include a method of mixing the (meth)acrylate compound (A), the cross-linking curing agent (B), the inorganic filler (C), and, if necessary, components other than the (meth)acrylate compound (A), the cross-linking curing agent (B), and the inorganic filler (C) to a predetermined content. In addition, in the case of obtaining a varnish-like composition containing an organic solvent, the method described below can be used.

[0071] [Prepreg, metal-clad laminate, wiring board, resin-coated metal foil, and resin-coated film] By using the resin composition according to this embodiment, a prepreg, a metal-clad laminate, a wiring board, a resin-coated metal foil, and a resin-coated film can be obtained as follows.

[0072] (Prepreg) FIG. 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment of the present invention.

[0073] 1, the prepreg 1 according to this embodiment comprises the resin composition or a semi-cured product of the resin composition 2, and a fibrous base material 3. This prepreg 1 comprises the resin composition or a semi-cured product of the resin composition 2, and the fibrous base material 3 present in the resin composition or the semi-cured product of the resin composition 2.

[0074] In this embodiment, the semi-cured product refers to a resin composition that has been partially cured to the extent that it can be further cured. That is, the semi-cured product refers to a resin composition that has been semi-cured (B-staged). For example, when a resin composition is heated, the viscosity initially gradually decreases, and then curing begins, and the viscosity gradually increases. In such a case, the semi-cured state may refer to a state between when the viscosity starts to increase and when the composition is completely cured.

[0075] The prepreg obtained using the resin composition according to this embodiment may comprise a semi-cured product of the resin composition as described above, or may comprise the uncured resin composition itself. That is, it may be a prepreg comprising a semi-cured product of the resin composition (the resin composition in B stage) and a fibrous base material, or a prepreg comprising the resin composition before curing (the resin composition in A stage) and a fibrous base material. Furthermore, the resin composition or the semi-cured product of the resin composition may be the resin composition that has been dried or heat-dried.

[0076] When producing the prepreg, the resin composition 2 is often prepared in a varnish form and used to impregnate the fibrous base material 3, which is a base material for forming the prepreg. That is, the resin composition 2 is usually often a resin varnish prepared in a varnish form. Such a varnish-like resin composition (resin varnish) is prepared, for example, as follows.

[0077] First, each component that is soluble in an organic solvent is added to the organic solvent and dissolved. Heating may be performed as necessary. Then, components that are insoluble in the organic solvent are added as needed, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, roll mill, or the like until a predetermined dispersion state is achieved, thereby preparing a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves the (meth)acrylate compound (A), the crosslinking curing agent (B), and the like and does not inhibit the curing reaction. Specific examples include toluene and methyl ethyl ketone (MEK).

[0078] Specific examples of the fibrous substrate include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. Glass cloth can be used to obtain a laminate with excellent mechanical strength, and flattened glass cloth is particularly preferred. A specific example of the flattening process is a method in which glass cloth is continuously pressed with a press roll at an appropriate pressure to compress the yarns flat. The thickness of commonly used fibrous substrates is, for example, 0.01 mm or more and 0.3 mm or less. The glass fibers constituting the glass cloth are not particularly limited, and examples include Q glass, NE glass, E glass, S glass, T glass, L glass, and L2 glass. The surface of the fibrous substrate may be treated with a silane coupling agent. The silane coupling agent is not particularly limited, but examples thereof include silane coupling agents having at least one group selected from the group consisting of a vinyl group, an acryloyl group, a methacryloyl group, a styryl group, an amino group, and an epoxy group in the molecule.

[0079] The method for producing the prepreg is not particularly limited as long as it can produce the prepreg. Specifically, when producing the prepreg, the resin composition according to the present embodiment is often prepared in the form of a varnish, as described above, and used as a resin varnish.

[0080] Specific examples of methods for producing the prepreg 1 include a method in which the resin composition 2, for example, a resin composition 2 prepared in a varnish form, is impregnated into a fibrous substrate 3, followed by drying. The resin composition 2 is impregnated into the fibrous substrate 3 by immersion, coating, or the like. Impregnation can be repeated multiple times as necessary. In this case, by repeating the impregnation using multiple resin compositions with different compositions and concentrations, it is also possible to adjust the final composition and impregnation amount to the desired one.

[0081] The fibrous substrate 3 impregnated with the resin composition (resin varnish) 2 is heated under desired conditions, for example, at 40°C to 180°C for 1 minute to 10 minutes. This heating process results in a prepreg 1 in an uncured (A-stage) or semi-cured (B-stage) state. The heating process also volatilizes the organic solvent from the resin varnish, reducing or eliminating the organic solvent.

[0082] (Metal-clad laminate) FIG. 2 is a schematic cross-sectional view showing an example of a metal-clad laminate 11 according to an embodiment of the present invention.

[0083] As shown in FIG. 2 , the metal-clad laminate 11 according to this embodiment includes an insulating layer 12 containing a cured product of the resin composition and a metal foil 13 disposed on the insulating layer 12. Examples of the metal-clad laminate 11 include a metal-clad laminate composed of an insulating layer 12 containing a cured product of the prepreg 1 shown in FIG. 1 and a metal foil 13 laminated together with the insulating layer 12. The insulating layer 12 may be composed of a cured product of the resin composition or a cured product of the prepreg. The thickness of the metal foil 13 varies depending on the performance required of the final wiring board and is not particularly limited. The thickness of the metal foil 13 can be appropriately set depending on the desired purpose, and is preferably, for example, 0.2 to 70 μm. Examples of the metal foil 13 include copper foil and aluminum foil. When the metal foil is thin, it may be a carrier-attached copper foil equipped with a release layer and a carrier to improve handling.

[0084] The method for producing the metal-clad laminate 11 is not particularly limited as long as it can produce the metal-clad laminate 11. Specifically, a method for producing the metal-clad laminate 11 using the prepreg 1 can be used. Examples of such a method include stacking one or more prepregs 1, placing a metal foil 13 such as copper foil on both sides or one side of the prepreg 1, and then heat-pressing and molding the metal foil 13 and the prepreg 1 to form an integrated laminate. That is, the metal-clad laminate 11 can be obtained by laminating the metal foil 13 on the prepreg 1 and then heat-pressing and molding the laminate. The heat-pressing conditions can be appropriately set depending on the thickness of the metal-clad laminate 11, the type of resin composition contained in the prepreg 1, and other factors. For example, the temperature can be 170 to 230°C, the pressure can be 0.5 to 5 MPa, and the time can be 60 to 150 minutes. The metal-clad laminate can also be produced without using a prepreg. For example, a method may be used in which a varnish-like resin composition is applied onto a metal foil to form a layer containing the resin composition on the metal foil, and then the layer is heated and pressed.

[0085] (Wiring Board) FIG. 3 is a schematic cross-sectional view showing an example of a wiring board 21 according to an embodiment of the present invention.

[0086] As shown in Fig. 3, wiring board 21 according to this embodiment has insulating layer 12 containing a cured product of the resin composition, and wiring 14 provided on insulating layer 12. Examples of wiring board 21 include a wiring board configured from insulating layer 12 used by curing prepreg 1 shown in Fig. 1, and wiring 14 laminated together with insulating layer 12 and formed by partially removing metal foil 13. Furthermore, insulating layer 12 may be made of a cured product of the resin composition, or may be made of a cured product of the prepreg.

[0087] The method for manufacturing the wiring board 21 is not particularly limited as long as the wiring board 21 can be manufactured. Specific examples include a method of manufacturing the wiring board 21 using the prepreg 1. Examples of this method include a method of manufacturing the wiring board 21 in which wiring is provided as a circuit on the surface of the insulating layer 12 by etching the metal foil 13 on the surface of the metal-clad laminate 11 manufactured as described above. That is, the wiring board 21 is obtained by forming a circuit by partially removing the metal foil 13 on the surface of the metal-clad laminate 11. In addition to the above methods, examples of the method for forming a circuit include circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0088] (Resin-Coated Metal Foil) FIG. 4 is a schematic cross-sectional view showing an example of a resin-coated metal foil 31 according to this embodiment.

[0089] As shown in Fig. 4, the resin-coated metal foil 31 according to this embodiment comprises a resin layer 32 containing the resin composition or a semi-cured product of the resin composition, and a metal foil 13. The resin-coated metal foil 31 has the metal foil 13 on the surface of the resin layer 32. That is, the resin-coated metal foil 31 comprises the resin layer 32 and the metal foil 13 laminated together with the resin layer 32. The resin-coated metal foil 31 may also comprise another layer between the resin layer 32 and the metal foil 13.

[0090] The resin layer 32 may contain a semi-cured product of the resin composition as described above, or may contain the uncured resin composition. That is, the resin-coated metal foil 31 may comprise a resin layer containing a semi-cured product of the resin composition (the resin composition in B-stage) and a metal foil, or a resin layer containing the resin composition before curing (the resin composition in A-stage) and a metal foil. The resin layer may contain the resin composition or a semi-cured product of the resin composition, and may or may not contain a fibrous substrate. The resin composition or the semi-cured product of the resin composition may be the resin composition that has been dried or heat-dried. The fibrous substrate may be the same as the fibrous substrate of a prepreg.

[0091] The metal foil may be any metal foil used in a metal-clad laminate or a resin-coated metal foil, and examples of the metal foil include copper foil and aluminum foil.

[0092] The resin-coated metal foil 31 may be provided with a cover film or the like as necessary. By providing a cover film, it is possible to prevent the inclusion of foreign matter, etc. The cover film is not particularly limited, but examples thereof include polyolefin films, polyester films, polymethylpentene films, and films formed by providing these films with a release agent layer.

[0093] The method for producing the resin-coated metal foil 31 is not particularly limited as long as the resin-coated metal foil 31 can be produced. Examples of the method for producing the resin-coated metal foil 31 include a method of applying the varnish-like resin composition (resin varnish) to the metal foil 13 and heating the applied resin composition. The varnish-like resin composition is applied to the metal foil 13 using, for example, a bar coater. The applied resin composition is heated, for example, at 40°C or higher and 180°C or lower for 0.1 minutes or longer and 10 minutes or shorter. The heated resin composition is formed on the metal foil 13 as an uncured resin layer 32. The heating volatilizes the organic solvent from the resin varnish, thereby reducing or removing the organic solvent.

[0094] (Resin-Coated Film) FIG. 5 is a schematic cross-sectional view showing an example of a resin-coated film 41 according to this embodiment.

[0095] 5 , the resin-coated film 41 according to this embodiment includes a resin layer 42 containing the resin composition or a semi-cured product of the resin composition, and a support film 43. The resin-coated film 41 includes the resin layer 42 and the support film 43 laminated together with the resin layer 42. The resin-coated film 41 may also include another layer between the resin layer 42 and the support film 43.

[0096] The resin layer 42 may contain a semi-cured product of the resin composition as described above, or may contain the uncured resin composition. That is, the resin-coated film 41 may comprise a resin layer containing a semi-cured product of the resin composition (the resin composition in B-stage) and a support film, or a resin-coated film comprising a resin layer containing the resin composition before curing (the resin composition in A-stage) and a support film. The resin layer may contain the resin composition or a semi-cured product of the resin composition, and may or may not contain a fibrous substrate. The resin composition or the semi-cured product of the resin composition may be obtained by drying or heat-drying the resin composition. The fibrous substrate may be the same as the fibrous substrate of a prepreg.

[0097] Any support film used for a resin-coated film can be used without limitation as the support film 43. Examples of the support film include electrically insulating films such as polyester film, polyethylene terephthalate (PET) film, polyimide film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, and polyarylate film.

[0098] The resin-coated film 41 may be provided with a cover film or the like as necessary. By providing a cover film, it is possible to prevent the inclusion of foreign matter, etc. The cover film is not particularly limited, but examples thereof include a polyolefin film, a polyester film, and a polymethylpentene film.

[0099] The support film and the cover film may be subjected to surface treatment such as matte treatment, corona treatment, release treatment, and roughening treatment, if necessary.

[0100] The method for producing the resin-coated film 41 is not particularly limited as long as it can produce the resin-coated film 41. Examples of methods for producing the resin-coated film 41 include a method in which the varnish-like resin composition (resin varnish) is applied to a support film 43 and heated. The varnish-like resin composition is applied to the support film 43 using, for example, a bar coater. The applied resin composition is heated, for example, at 40°C or higher and 180°C or lower for 0.1 minutes or longer and 10 minutes or shorter. The heated resin composition is formed on the support film 43 as an uncured resin layer 42. The heating volatilizes the organic solvent from the resin varnish, thereby reducing or removing the organic solvent.

[0101] When cured, the resin composition according to this embodiment exhibits excellent low dielectric properties, such as a low relative dielectric constant, and a cured product with a low coefficient of thermal expansion. Therefore, when cured, the prepreg exhibits excellent low dielectric properties, such as a low relative dielectric constant, and a cured product with a low coefficient of thermal expansion. The resin-coated metal foil and the resin-coated film are, respectively, resin-coated metal foils and resin-coated films, each comprising a resin layer that becomes an insulating layer containing the cured product upon curing. The metal-clad laminate and the wiring board are, respectively, metal-clad laminates and wiring boards, each comprising an insulating layer containing the cured product. The prepreg, the resin-coated film, the resin-coated metal foil, and the metal-clad laminate can be suitably used to manufacture the wiring board, and can also be used, for example, to manufacture a multilayer wiring board. For example, in the case of the resin-coated film, a multilayer wiring board can be manufactured by laminating the film on a wiring board and then peeling off the support film, or by laminating the film on a wiring board after peeling off the support film. In the case of the resin-coated metal foil, a multilayer wiring board can be manufactured by laminating the film on a wiring board. In this way, by using the resin-coated film, the resin-coated metal foil, etc., a multilayer wiring board having an insulating layer containing the cured product can be manufactured.

[0102] As described above, this specification discloses various aspects of the technology, the main technologies of which are summarized below.

[0103] The resin composition according to the first aspect of the present invention is a resin composition comprising: a (meth)acrylate compound (A) having an indane skeleton represented by the general formula (1); a cross-linking curing agent (B) having a molecular weight of less than 400 and having two or more unsaturated double bonds in the molecule; and an inorganic filler (C).

[0104] A resin composition according to a second aspect of the present invention is the resin composition according to the first aspect of the present invention, wherein X is a methacryloyloxy group.

[0105] A resin composition according to a third aspect of the present invention is the resin composition according to the first or second aspect of the present invention, wherein the (meth)acrylate compound (A) comprises a methacrylate compound (a) having an indane skeleton represented by the general formula (2).

[0106] A resin composition according to a fourth aspect of the present invention is the resin composition according to any one of the first to third aspects of the present invention, wherein the cross-linking curing agent (B) comprises at least one selected from the group consisting of an allyl compound, a vinyl compound, a maleimide compound, and a (meth)acrylate compound (b) other than the (meth)acrylate compound (A).

[0107] A resin composition according to a fifth aspect of the present invention is the resin composition according to any one of the first to fourth aspects of the present invention, further comprising an organic peroxide (D).

[0108] A resin composition according to a sixth aspect of the present invention is the resin composition according to any one of the first to fifth aspects of the present invention, wherein a content ratio of the (meth)acrylate compound (A) to the cross-linking curing agent (B) is 90:10 to 50:50 by mass.

[0109] A prepreg according to a seventh aspect of the present invention is a prepreg comprising the resin composition according to any one of the first to sixth aspects of the present invention or a semi-cured product of the resin composition, and a fibrous base material.

[0110] The resin-coated film according to the eighth aspect of the present invention is a resin-coated film comprising a resin layer containing the resin composition according to any one of the first to sixth aspects of the present invention or a semi-cured product of the resin composition, and a support film.

[0111] A resin-coated metal foil according to a ninth aspect of the present invention is a resin-coated metal foil comprising a resin layer containing the resin composition according to any one of the first to sixth aspects of the present invention or a semi-cured product of the resin composition, and a metal foil.

[0112] A metal-clad laminate according to a tenth aspect of the present invention is a metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of the first to sixth aspects of the present invention, and a metal foil.

[0113] A metal-clad laminate according to an eleventh aspect of the present invention is a metal-clad laminate comprising an insulating layer containing a cured product of the prepreg according to the seventh aspect of the present invention and a metal foil.

[0114] A wiring board according to a twelfth aspect of the present invention is a wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of the first to sixth aspects of the present invention, and wiring.

[0115] A wiring board according to a thirteenth aspect of the present invention is a wiring board comprising an insulating layer containing a cured product of the prepreg according to the seventh aspect of the present invention and wiring.

[0116] According to the present invention, it is possible to provide a resin composition that has excellent low dielectric properties such as a low relative permittivity, that satisfactorily suppresses an increase in dielectric loss tangent due to water absorption, and that can yield a cured product with a low thermal expansion coefficient. Furthermore, according to the present invention, it is possible to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board, which are obtained using the resin composition.

[0117] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0118] Examples 1 to 3 and Comparative Example In these examples, each component used in preparing the resin composition will be described.

[0119] ((Meth)acrylate compound (A)) Methacrylate compound: represented by the formula (2), R １ and R ２ is a methyl group and n is 1.6 (NE-V-RD004 manufactured by DIC Corporation)

[0120] (Modified PPE) Modified PPE: polyphenylene ether compound having a methacryloyl group at the end (SA9000 manufactured by SABIC Innovative Plastics, a modified polyphenylene ether in which the terminal hydroxyl group of polyphenylene ether is modified with a methacryloyl group, weight average molecular weight Mw 2000)

[0121] (Crosslinking curing agent (B)) TAIC: triallyl isocyanurate (TAIC manufactured by Mitsubishi Chemical Corporation, molecular weight: 249.27, unsaturated double bonds (allyl groups): 3) DCP: tricyclodecane dimethanol dimethacrylate (NK ester DCP manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight: 332.44, unsaturated double bonds (methacryloyl groups): 2)

[0122] (Organic Peroxide (D)) PBP: α,α'-di(t-butylperoxy)diisopropylbenzene (Perbutyl P manufactured by NOF Corporation)

[0123] (Inorganic filler (C)) Silica: Spherical silica surface-treated with vinylsilane (SC2300-SVJ manufactured by Admatechs Co., Ltd.)

[0124] [Preparation Method] First, the components other than the inorganic filler were added to toluene and mixed to a solids concentration of approximately 60% by mass in the composition (parts by mass) shown in Table 1. The resulting mixture was stirred for 60 minutes. Thereafter, if an inorganic filler was included, the inorganic filler was added to the resulting mixture in the composition (parts by mass) shown in Table 1, and dispersed using a bead mill. This resulted in a varnish-like resin composition (varnish).

[0125] Next, a prepreg was obtained as follows.

[0126] A fibrous substrate (glass cloth: #1067 type, NE glass, manufactured by Nitto Boseki Co., Ltd.) was impregnated with the obtained varnish and then dried by heating at 130° C. for 3 minutes to produce a prepreg. The content of the components that constitute the resin by the curing reaction relative to the prepreg (resin content) was adjusted to be approximately 74% by mass.

[0127] An evaluation substrate (metal-clad laminate) was obtained as follows.

[0128] Two sheets of the obtained prepreg were stacked, and 12 μm thick copper foil (3EC-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on both sides. This was used as a pressure body, and heated to a temperature of 220°C at a temperature increase rate of 3°C / min, and then heated and pressed at 220°C for 120 minutes under a pressure of 3 MPa, to obtain an evaluation substrate (metal-clad laminate) with copper foil adhered to both sides and an insulating layer thickness of approximately 138 μm.

[0129] The evaluation substrate prepared as described above was evaluated by the following method.

[0130] [Dielectric Properties (Dielectric Constant Dk and Dielectric Loss Tangent Df)] The copper foil was removed from the evaluation substrate by etching. The substrate thus obtained was used as a test specimen, and the dielectric constant and dielectric loss tangent at 10 GHz were measured using a cavity resonator perturbation method. Specifically, the dielectric constant (Dk) and dielectric loss tangent (Df) of the test specimen at 10 GHz were measured using a network analyzer (N5230A manufactured by Keysight Technologies, Inc.). If the measured dielectric constant Dk was less than 3.1, the test specimen was judged to be "passed." Furthermore, if the measured dielectric loss tangent Df was less than 0.0035, the test specimen was judged to be "passed." Note that the dielectric constant Dk and dielectric loss tangent Df are the dielectric constant and dielectric loss tangent of the test specimen before water absorption.

[0131] [Change in Dk (ΔDk) and Change in Dielectric Loss Tangent (ΔDf) Due to Water Absorption] The dielectric constant Dk and dielectric loss tangent Df of the test piece after water absorption were measured by the same method as above. Then, the difference ΔDk between the dielectric constant of the test piece after water absorption and the dielectric constant of the test piece before water absorption was calculated. In addition, the difference ΔDf between the dielectric loss tangent of the test piece after water absorption and the dielectric loss tangent of the test piece before water absorption was calculated.

[0132] If the change in dielectric constant ΔDk when the test piece was allowed to absorb water (dielectric constant of the test piece after absorbing water - dielectric constant of the test piece before absorbing water) was less than 0.05, it was judged to be "passed." If the change in dielectric tangent ΔDf when the test piece was allowed to absorb water (dielectric tangent of the test piece after absorbing water - dielectric tangent of the test piece before absorbing water) was less than 0.002, it was judged to be "passed."

[0133] [Thermal expansion coefficient (50 to 260 ° C)] An unclad plate obtained by etching the copper foil from the evaluation substrate (metal-clad laminate) was used as a test specimen. The thermal expansion coefficient in the plane direction (tensile direction, Y direction) of the evaluation substrate at a temperature below the glass transition temperature of the cured resin composition was measured by the TMA method (thermo-mechanical analysis). Specifically, a TMA device ("TMA7100" manufactured by Hitachi High-Tech Science Corporation) was used for the measurement in tensile mode. In order to eliminate the influence of thermal distortion of the test specimen, the test specimen was pulled in the Y direction with a load of 10 g, and then heated from 30 ° C to 320 ° C at a heating rate of 10 ° C / min, and then cooled to room temperature. Then, the test specimen was pulled in the Y direction with a load of 10 g, and heated from 30 ° C to 320 ° C at a heating rate of 20 ° C / min. A temperature displacement chart was obtained during this heating period. The average thermal expansion coefficient from 50 to 260°C was calculated from the temperature change chart obtained at this time. The smaller this average thermal expansion coefficient (Y-CTE 50-260°C) is, the more favorable the result is, and in this test, a value of less than 17 ppm / °C was judged to be "pass."

[0134] [Glass Transition Temperature (Tg)] An unclad plate obtained by removing the metal foil (copper foil) from the evaluation substrate (metal-clad laminate) by etching was used as a test piece, and the glass transition temperature Tg of the cured resin composition was measured using a viscoelasticity spectrometer "DMS6100" manufactured by Hitachi High-Tech Science Corp. Dynamic viscoelasticity measurement (DMA) was performed using a tensile module at a frequency of 10 Hz, and the temperature at which tan δ was maximized when the temperature was increased from room temperature to 340°C at a heating rate of 5°C / min was taken as the glass transition temperature Tg (°C).

[0135] The results of the above evaluations are shown in Table 1 together with the formulations of the resin compositions.

[0136] As can be seen from Table 1, in the case of resin compositions (Examples 1 to 3) containing a (meth)acrylate compound (A) having an indane skeleton represented by the general formula (1), a cross-linking curing agent (B) having a molecular weight of less than 400 and two or more unsaturated double bonds in the molecule, and an inorganic filler (C), the resin compositions (Examples 1 to 3) exhibited excellent low dielectric properties such as a low dielectric constant, sufficient suppression of the increase in dielectric loss tangent due to water absorption, and a cured product with a low thermal expansion coefficient, compared to the case (Comparative Example) in which the modified PPE was used instead of the (meth)acrylate compound (A) having an indane skeleton represented by the general formula (1). Furthermore, a comparison of Examples 1 and 2 with Example 3 revealed that when TAIC was used as the cross-linking curing agent (B) (Examples 1 and 2) exhibited excellent low dielectric properties such as a low dielectric constant, sufficient suppression of the increase in dielectric loss tangent due to water absorption, and a cured product with not only a low thermal expansion coefficient but also a high glass transition temperature was obtained. Furthermore, it was found that when DCP was used as the cross-linking curing agent (B) (Example 3), a cured product was obtained that could further suppress the increase in relative dielectric constant and the increase in dielectric loss tangent due to water absorption.

[0137] This application is based on Japanese Patent Application No. 2024-121163 filed on July 26, 2024, the contents of which are incorporated herein by reference.

[0138] In order to express the present invention, the present invention has been properly and sufficiently described through the embodiments in the above, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims.

[0139] According to the present invention, there is provided a resin composition which has excellent low dielectric properties such as a low relative permittivity, is sufficiently inhibited from increasing in dielectric loss tangent due to water absorption, and can give a cured product with a low coefficient of thermal expansion. Also provided according to the present invention are a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board which can be obtained using the resin composition.

Claims

1. A resin composition comprising: (A) a (meth)acrylate compound having an indane skeleton represented by the following general formula (1); (B) a cross-linking curing agent having a molecular weight of less than 400 and having two or more unsaturated double bonds in the molecule; and (C) an inorganic filler. [In the above formula (1), X represents a (meth)acryloyloxy group; Ra and Rb each independently represent an alkyl group, aryl group, aralkyl group, or cycloalkyl group having 1 to 12 carbon atoms; j represents an integer of 1 to 3; k and l each independently represent an integer of 0 to 4; n is an average repeating unit and represents a number of 0.5 to 20; and m represents an integer of 0 to 2.] 2. The resin composition according to claim 1, wherein X is a methacryloyloxy group.

3. The resin composition according to claim 1, wherein the (meth)acrylate compound (A) comprises a methacrylate compound (a) having an indane skeleton represented by the following general formula (2): [In the above formula (2), R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and R １ and R ２ are not both hydrogen atoms at the same time, and n is the average repeating unit and is a value of 0.5 to 20.

4. The resin composition according to claim 1, wherein the cross-linking curing agent (B) comprises at least one selected from the group consisting of allyl compounds, vinyl compounds, maleimide compounds, and (meth)acrylate compounds (b) other than the (meth)acrylate compound (A).

5. The resin composition according to claim 1, further comprising an organic peroxide (D).

6. The resin composition according to claim 1, wherein the content ratio of the (meth)acrylate compound (A) to the crosslinking curing agent (B) is 90:10 to 50:50 by mass.

7. A prepreg comprising the resin composition according to any one of claims 1 to 6 or a semi-cured product of said resin composition and a fibrous base material.

8. A resin-coated film comprising a resin layer containing the resin composition according to any one of claims 1 to 6 or a semi-cured product of said resin composition, and a support film.

9. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 6 or a semi-cured product of said resin composition, and a metal foil.

10. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 6 and a metal foil.

11. A metal-clad laminate comprising an insulating layer containing the cured product of the prepreg according to claim 7 and a metal foil.

12. A wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 6, and wiring.

13. A wiring board comprising an insulating layer containing the cured product of the prepreg according to claim 7 and wiring.

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