Resin composition, and prepreg, resin-coated film, resin-coated metal foil, metal-clad laminate, and wiring board each obtained using same

Abstract

One aspect of the present invention relates to a resin composition comprising a polyfunctional vinyl aromatic copolymer (A) and a silica filler (B), wherein the silica filler (B) has a particle size distribution having a volume-based 10%-cumulative particle diameter (D10) of 0.7 μm or larger, a volume-based 50%-cumulative particle diameter (D50) of 0.9-4.0 μm, and a volume-based 90%-cumulative particle diameter (D90) of 4.5 μm or less.

Description

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

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

[0002] In recent years, with the increase in the amount of information processed in various electronic devices, there has been rapid progress in packaging technologies, such as higher integration of semiconductor devices, higher density wiring, and multi-layering. Thermosetting resins are generally used as substrate materials for the base materials of wiring boards used in various electronic devices, and they are required to have high heat resistance (glass transition temperature) to cope with high temperatures such as reflow and multi-layering, as well as low dielectric constant and dielectric loss tangent to increase signal transmission speed 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 discloses a curable resin composition containing (A) a soluble polyfunctional vinyl aromatic copolymer containing a repeating unit (a) derived from a divinyl aromatic compound and a repeating unit (b) derived from a monovinyl aromatic compound, (B) a modified polyphenylene ether in which at least a portion of the terminals of the main chain have a functional group other than a hydroxyl group, and (C) a flame retardant.

[0005] Furthermore, Patent Document 2 discloses a terminal-modified soluble polyfunctional vinyl aromatic copolymer obtained by polymerizing a divinyl aromatic compound (a), a monovinyl aromatic compound (b), and a (meth)acrylic acid ester compound (c) in the presence of one or more catalysts (d) selected from the group consisting of Lewis acid catalysts, strong inorganic acids, and organic sulfonic acids, the copolymer having terminal groups derived from the (meth)acrylic acid ester compound (c) at some of its terminals.

[0006] Patent Document 3 describes a curable resin composition containing a modified polyphenylene ether in which a hydroxyl group present at the end of the main chain is modified with a (meth)acrylic acid compound, and a polyfunctional vinyl aromatic copolymer containing a repeating unit derived from a divinyl aromatic compound and a repeating unit derived from a monovinyl aromatic compound.

[0007] Resin compositions containing the polyfunctional vinyl aromatic copolymers described in Patent Documents 1 to 3 are said to be capable of providing cured products or molded articles having improved heat resistance, compatibility, dielectric properties, moist heat reliability, thermal oxidative degradation resistance, etc.

[0008] Incidentally, it is common practice to incorporate an inorganic filler into a curable resin composition for the purpose of improving the heat resistance, flame retardancy, etc. of the cured product. However, it has been found that resin compositions containing a polyfunctional vinyl aromatic copolymer as shown in the above-mentioned document may be inferior in fluidity and adhesion when an inorganic filler is added.

[0009] JP 2011-46816 A JP 2020-105352 A JP 2018-168347 A

[0010] The present invention has been made in view of the above circumstances, and aims to provide a resin composition that has low dielectric properties in a cured product while also exhibiting excellent fluidity and adhesion, and also aims to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that use the resin composition.

[0011] A resin composition according to one aspect of the present invention comprises a polyfunctional vinyl aromatic copolymer (A) and a silica filler (B), wherein the silica filler (B) has a volume-based cumulative 10% particle size (D10) of 0.7 μm or more, a volume-based cumulative 50% particle size (D50) of 0.9 μm or more and 4.0 μm or less, and a volume-based cumulative 90% particle size (D90) of 4.5 μm or less in a particle size distribution.

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

[0013] (Resin Composition) A resin composition according to an embodiment of the present invention (hereinafter simply referred to as the resin composition) comprises a polyfunctional vinyl aromatic copolymer (A) and a silica filler (B). In the particle size distribution of the silica filler (B), the cumulative 10% particle size (D10) on a volume basis is 0.7 μm or more, the cumulative 50% particle size (D50) on a volume basis is 0.9 μm or more and 4.0 μm or less, and the cumulative 90% particle size (D90) on a volume basis is 4.5 μm or less.

[0014] The resin composition of this embodiment contains the polyfunctional vinyl aromatic copolymer (A) and the silica filler (B), and thus the cured product of the resin composition can have low dielectric properties. Furthermore, since the silica filler (B) has the above-mentioned structure, the resin composition of this embodiment also has excellent adhesion (particularly interlayer adhesion) and fluidity. In this specification, "fluidity" refers to resin fluidity under specified molding conditions as shown in the examples below. Excellent fluidity has the advantage of excellent circuit filling properties during multilayer molding.

[0015] That is, according to the present invention, a resin composition can be provided that has low dielectric properties in the cured product, as well as excellent fluidity and adhesion. Furthermore, by using the resin composition, it is possible to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that have excellent properties.

[0016] Each component of the resin composition according to this embodiment will be specifically described below.

[0017] <Polyfunctional vinyl aromatic copolymer (A)> The polyfunctional vinyl aromatic copolymer (A) of this embodiment is not particularly limited as long as it is a polyfunctional vinyl aromatic copolymer containing a repeating unit (a1) derived from a divinyl aromatic compound. Preferably, the polyfunctional vinyl aromatic copolymer (A) contains the repeating unit (a1) derived from the divinyl aromatic compound and the repeating unit (a2) derived from a monovinyl aromatic compound.

[0018] More specifically, for example, the polyfunctional vinyl aromatic polymer (A) used in the resin composition of this embodiment has repeating units (a1) derived from a divinyl aromatic compound and repeating units (a2) derived from a monovinyl aromatic compound, and when the sum of the repeating units (a1) and the repeating units (a2) is taken as 100 mol %, it contains 2 mol % or more and less than 95 mol % of the repeating units (a1) and 5 mol % or more and less than 98 mol % of the repeating units (a2).

[0019] The polyfunctional vinyl aromatic copolymer (A) preferably further contains a repeating unit (a1-1) represented by the following formula (1) as part of the repeating unit (a1) derived from a divinyl aromatic compound:

[0020]

[0021] In formula (1), R １ represents an aromatic hydrocarbon group having 6 to 30 carbon atoms.

[0022] Preferred examples of the polyfunctional vinyl aromatic copolymer (A) include soluble polyfunctional vinyl aromatic copolymers in which the molar fraction of the repeating unit (a1-1) in the sum of the repeating units (a1) and (a2) satisfies the following formula (2): 0.02≦(a1-1) / [(a1)+(a1)]≦0.8 (2), the number average molecular weight is 300 to 100,000, the molecular weight distribution expressed as the ratio of the weight average molecular weight to the number average molecular weight is 100.0 or less, and the copolymer is soluble in toluene, xylene, tetrahydrofuran, dichloroethane, or chloroform. Hereinafter, the soluble polyfunctional vinyl aromatic copolymer will also be referred to simply as "copolymer."

[0023] The soluble polyfunctional vinyl aromatic copolymer contains 2 mol % or more but less than 95 mol % of repeating units (a1) and 5 mol % or more but less than 98 mol % of repeating units (a2), where the total of repeating units (a1) and (a2) is taken as 100 mol %, and preferably contains 2 to 80 mol % of repeating units (a1-1), where the total of repeating units (a1) and (a2) is taken as 100 mol %.

[0024] The soluble polyfunctional vinyl aromatic copolymer preferably has a number average molecular weight Mn of 300 to 100,000, a molecular weight distribution expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw / Mn) of 100.0 or less, and is preferably soluble in toluene, xylene, tetrahydrofuran, dichloroethane, or chloroform.

[0025] The soluble polyfunctional vinyl aromatic copolymer is not limited, but examples thereof include copolymers containing structural units derived from a repeating unit (a2) derived from the monovinyl aromatic compound represented by the following formula (3) and a repeating unit (a1) derived from the divinyl aromatic compound represented by the following formula (4) and formula (5). These structural units may be arranged regularly or randomly.

[0026]

[0027]

[0028]

[0029] In the formula (3), R ２ represents an aromatic hydrocarbon group having 6 to 30 carbon atoms derived from the monovinyl aromatic compound, and in the formulas (4) and (5), R １ represents an aromatic hydrocarbon group having 6 to 30 carbon atoms derived from the divinyl aromatic compound, and in the formulas (3) to (5), h to k each independently represent an integer of 0 to 200, provided that the total of these is 2 to 20,000.

[0030] Suitable examples of the soluble polyfunctional vinyl aromatic copolymer include those represented by the formulas (3) to (5) above, where R１ and R ２ and copolymers comprising repeating units which are aromatic hydrocarbon groups selected from the group consisting of an optionally substituted phenyl group, an optionally substituted biphenyl group, an optionally substituted naphthalene group, and an optionally substituted terphenyl group.

[0031] The soluble polyfunctional vinyl aromatic copolymer is preferably solvent-soluble. The repeating units referred to in this specification are derived from monomers and include units that are present and appear repeatedly in the main chain of the copolymer, as well as units or terminal groups present at the end or side chain. Repeating units are also referred to as structural units. The terminal groups referred to in this specification include those derived from the above-mentioned monomers as well as terminal groups derived from the chain transfer agent described below.

[0032] The structural unit (a1) derived from a divinylaromatic compound is contained in an amount of 2 mol% or more but less than 95 mol% of the total of the structural units (a2) derived from the divinylaromatic compound and the monovinyl aromatic compound. The structural unit (a1) derived from the divinylaromatic compound can have a variety of structures, such as one in which only one of two vinyl groups has reacted, or two in which two have reacted. Of these, the repeating unit represented by the above formula (a1-1) in which only one vinyl group has reacted preferably accounts for 2 to 80 mol%, more preferably 5 to 70 mol%, even more preferably 10 to 60%, and particularly preferably 15 to 50% of the total. A content of 2 to 80 mol% is believed to result in a low dielectric loss tangent, high toughness, excellent heat resistance, and excellent compatibility with other resins. When the repeating unit (a1-1) in which only one vinyl group has reacted represented by the above formula (1) accounts for less than 2 mol% of the total, heat resistance tends to decrease, while when it exceeds 80 mol%, interlayer peel strength tends to decrease when formed into a laminate.

[0033] The soluble polyfunctional vinyl aromatic copolymer contains structural units (a2) derived from a monovinyl aromatic compound in an amount of 5 mol% or more and less than 98 mol% based on the total amount. More preferably, it contains 10 mol% or more and less than 90 mol%. Even more preferably, it contains 15 mol% or more and less than 85 mol%. If the structural units (a2) derived from the monovinyl aromatic compound are less than 5 mol% based on the total amount, moldability may be insufficient, and if they exceed 98 mol%, the heat resistance of the cured product may be insufficient.

[0034] The vinyl group present in the above formula (1) acts as a cross-linking component and contributes to the development of heat resistance of the soluble polyfunctional vinyl aromatic copolymer.On the other hand, the structural unit (a2) derived from a monovinyl aromatic compound does not have a vinyl group, since it is generally considered that polymerization proceeds by a 1,2-addition reaction of the vinyl group.In other words, the structural unit (a2) derived from a monovinyl aromatic compound does not act as a cross-linking component, but contributes to the development of moldability.

[0035] Styrene is a preferred example of the monovinyl aromatic compound. Furthermore, a monovinyl aromatic compound other than styrene can also be used together with styrene. In this case, when the total content of the structural unit (a2-1) derived from styrene and the structural unit (a2-2) derived from a monovinyl aromatic compound other than styrene is taken as 100 mol%, the content of the structural unit (a2-1) derived from styrene is preferably 99 to 20 mol%, more preferably 98 to 30 mol%. A content of (a2-1) within the above range is preferred because it combines thermal oxidative degradation resistance and moldability. When the structural unit (a2-1) is greater than 99 mol%, heat resistance tends to decrease, and when the structural unit (a2-2) is greater than 80 mol%, moldability tends to decrease.

[0036] The number average molecular weight of the soluble polyfunctional vinyl aromatic copolymer (number average molecular weight measured using GPC in terms of standard polystyrene) is preferably 300 to 100,000, more preferably 400 to 50,000, and even more preferably 500 to 10,000. If Mn is less than 300, the amount of monofunctional copolymer component contained in the soluble polyfunctional vinyl aromatic copolymer increases, and the heat resistance of the cured product tends to decrease. If Mn is more than 100,000, gel tends to be easily formed and the viscosity increases, and therefore molding processability tends to decrease.

[0037] The soluble polyfunctional vinyl aromatic copolymer has a molecular weight distribution (Mw / Mn) expressed as the ratio of the weight average molecular weight (weight average molecular weight measured using GPC in terms of standard polystyrene) to Mn of 100.0 or less, preferably 50.0 or less, more preferably 1.5 to 30.0, and most preferably 2.0 to 20.0. If Mw / Mn exceeds 100.0, the processability of the soluble polyfunctional vinyl aromatic copolymer tends to deteriorate and gel tends to form.

[0038] The soluble polyfunctional vinyl aromatic copolymer is soluble in toluene, xylene, tetrahydrofuran, dichloroethane or chloroform as a solvent, and is preferably soluble in any of the above-mentioned solvents.To be a solvent-soluble polyfunctional copolymer, it is necessary that a part of the vinyl group of divinylbenzene remains uncrosslinked and has an appropriate degree of crosslinking.Here, soluble in a solvent means that the soluble polyfunctional vinyl aromatic copolymer dissolves in 100g of the solvent in an amount of 5g or more, preferably 30g or more, more preferably 50g or more.

[0039] The divinyl aromatic compound serves to form a branched structure to impart multifunctionality, and also serves as a cross-linking component to impart heat resistance when the resulting soluble multifunctional vinyl aromatic copolymer is thermally cured. Examples of divinyl aromatic compounds are not limited as long as they are aromatic compounds having two vinyl groups, but preferred examples include divinylbenzene (including positional isomers or mixtures thereof), divinylnaphthalene (including positional isomers or mixtures thereof), and divinylbiphenyl (including positional isomers or mixtures thereof). These compounds may be used alone or in combination of two or more. From the viewpoint of moldability, divinylbenzene (m-isomer, p-isomer, or a mixture of positional isomers thereof) is more preferred.

[0040] Examples of the monovinyl aromatic compound include styrene and monovinyl aromatic compounds other than styrene, but it is preferable to use styrene as an essential component and to use a monovinyl aromatic compound other than styrene in combination.

[0041] Styrene, as a monomer component, serves to impart low dielectric properties and thermal oxidation resistance to the soluble polyfunctional vinyl aromatic copolymer, and also serves as a chain transfer agent to control the molecular weight of the soluble polyfunctional vinyl aromatic copolymer. In addition, the monovinyl aromatic compound other than styrene improves the solvent solubility and processability of the soluble polyfunctional vinyl aromatic copolymer.

[0042] Examples of monovinyl aromatic compounds other than styrene include, but are not limited to, aromatic compounds other than styrene having one vinyl group, such as vinyl aromatic compounds such as vinylnaphthalene and vinylbiphenyl; and nuclear alkyl-substituted vinyl aromatic compounds such as o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylvinylbenzene, m-ethylvinylbenzene, and p-ethylvinylbenzene. Ethylvinylbenzene (including each positional isomer or a mixture thereof), ethylvinylbiphenyl (including each positional isomer or a mixture thereof), or ethylvinylnaphthalene (including each positional isomer or a mixture thereof) are preferred because they prevent gelation of the soluble polyfunctional vinyl aromatic copolymer, are highly effective in improving solvent solubility and processability, are low cost, and are easily available. More preferred is ethylvinylbenzene (m-isomer, p-isomer, or a mixture of these positional isomers) from the viewpoints of dielectric properties and cost.

[0043] In addition to the divinyl aromatic compound and the monovinyl aromatic compound, one or more other monomer components such as a trivinyl aromatic compound, a trivinyl aliphatic compound, a divinyl aliphatic compound, or a monovinyl aliphatic compound may be used, and structural units (b) derived from these may be introduced into the soluble polyfunctional vinyl aromatic copolymer, provided that the effects of the present invention are not impaired.

[0044] Examples of the other monomer components include 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, 1,2,4-trivinylcyclohexane, ethylene glycol diacrylate, butadiene, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triallyl isocyanurate, etc. These can be used alone or in combination of two or more.

[0045] The molar fraction of the other monomer component relative to the sum of all monomer components is preferably less than 30 mol %. In other words, the molar fraction of the repeating unit (b) derived from the other monomer component relative to the sum of the structural units (a1), (a2), and (b) derived from all monomer components constituting the copolymer is preferably less than 30 mol %.

[0046] The soluble polyfunctional vinyl aromatic copolymer can be obtained by polymerizing a monomer containing the divinyl aromatic compound and the monovinyl aromatic compound in the presence of a Lewis acid catalyst. Furthermore, a known chain transfer agent (CTR) can be added during the polymerization to control the molecular weight.

[0047] The content of the polyfunctional vinyl aromatic copolymer (A) is preferably 5% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 40% by mass or less, based on the total amount of the resin components including the polyfunctional vinyl aromatic copolymer (A). By including the polyfunctional vinyl aromatic copolymer (A) in such a content, the resin composition of this embodiment can more reliably obtain low dielectric properties in the cured product thereof.

[0048] <Silica Filler (B)> The silica filler (B) used in this embodiment has a volume-based cumulative 10% particle size (D10) of 0.7 μm or more, a volume-based cumulative 50% particle size (D50) of 0.9 μm or more and 4.0 μm or less, and a volume-based cumulative 90% particle size (D90) of 4.5 μm or less in its particle size distribution. By using silica filler (B) with such particle sizes, the fluidity and adhesion of a resin composition containing polyfunctional vinyl aromatic copolymer (A) can be improved. The particle sizes (D10, D50, and D50) may be in the above-mentioned particle size range as long as D10<D50<D90.

[0049] The particle size (D10) is more preferably in the range of 0.7 μm or more and 2.0 μm or less. The upper limit of the particle size (D10) is more preferably 1.5 μm or less, more preferably 0.9 μm or less, and even more preferably less than 0.9 μm. The particle size (D50) is more preferably in the range of 0.9 μm or more and 3.0 μm or less. The particle size (D90) is more preferably in the range of 1.0 μm or more and 4.5 μm or less. The lower limit of the particle size (D90) is more preferably 1.4 μm or more, more preferably 3.0 μm or more, and even more preferably more than 3.0 μm.

[0050] In this specification, the particle size distribution is a value measured by particle size distribution measurement using a laser diffraction / scattering method, and can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device "SALD-2300" (manufactured by Shimadzu Corporation) used in the examples described later.

[0051] The silica filler (B) is not particularly limited as long as it satisfies the above particle size requirements and can be used as an inorganic filler. Preferably, a spherical silica filler with a reduced hydroxy group content is used. The spherical silica filler preferably has an average particle diameter between 0.1 μm and 5 μm, and more preferably between 0.15 μm and 4.5 μm. The spherical silica filler preferably does not contain silica fillers with a diameter of 50 nm or less. In this embodiment, the "average particle diameter" refers to the arithmetic mean of the volume-based frequency distribution in the particle size distribution.

[0052] The silica filler (B) satisfying the above-mentioned particle diameters (D10, D50 and D90) can be obtained, for example, by the following method.

[0053] First, R ｍ Six ３ By the hydrolysis and condensation reaction of the above, a spherical polysiloxane containing T units is obtained. ３ are hydrogen atoms or independently selectable organic groups having 1 to 18 carbon atoms, X is a hydrolyzable group, and the T units are R ３ SiO ３The spherical polysiloxane is then calcined under a dry oxidizing gas atmosphere to obtain spherical silica powder with a low hydroxyl group content. The calcination temperature is between 850 and 1200°C. The obtained spherical silica powder has a Q １ Unit, Q ２ Unit, Q ３ Units and Q ４ It is composed of at least one unit selected from the following: １ The unit is Si(OH) ３ O- and Q ２ The unit is Si(OH) ２ O ２ - and Q ３ The unit is SiOHO ３ - and Q ４ The unit is SiO ４ - and Q ４ The content of the unit is greater than or equal to 95%.

[0054] In the silica filler (B) of this embodiment, it is preferable that the content of hydroxy groups (OH groups) is low. From this viewpoint, the Q ４ The content of the unit is preferably 95% or more, which is thought to have the advantage of reducing dielectric loss.

[0055] The hydrolyzable group is preferably an alkoxy group or a halogen atom. The catalyst for the hydrolysis condensation reaction may be a salt or an acid.

[0056] The oxidizing gas preferably contains oxygen gas to completely oxidize the organic compounds in the polysiloxane. A preferred oxygen gas is air. The calcination step is preferably carried out by electrical heating or indirect gas heating. The calcination temperature is more preferably between 850 and 1100°C, and the calcination time is preferably between 6 and 12 hours.

[0057] The spherical polysiloxane may further contain Q units, D units, and / or M units, where Q units = SiO ４ - and D unit = R ４ R ５ SiO ２- and M unit = R ６ R ７ R ８ SiO ２ In the above chemical formula, R ４ , R ５ , R ６ , R ７ and R ８ are each independently selected hydrogen atoms or hydrocarbon groups of 1 to 18 carbon atoms.

[0058] Furthermore, the obtained spherical silica powder may be subjected to a surface treatment. That is, the silica filler (B) of this embodiment may be a surface-treated silica filler or a non-surface-treated silica filler. Examples of the surface treatment include treatment with a silane coupling agent.

[0059] Silane coupling agents that can be used for surface treatment include (R ９ ) ａ (R １０ ) ｂ Si(M) ４－ａ－ｂ In the above chemical formula, R ９ and R １０ are independently selectable hydrocarbon groups having 1 to 18 carbon atoms, hydrogen atoms, or hydrocarbon groups having 1 to 18 carbon atoms substituted with a functional group. The functional groups include at least one selected from the group consisting of organic functional groups such as vinyl groups, allyl groups, styryl groups, epoxy groups, aliphatic amino groups, aromatic amino groups, methacryloxypropyl groups, acryloxypropyl groups, ureidopropyl groups, chloropropyl groups, mercaptopropyl groups, polysulfide groups, and isocyanatopropyl groups. M is an alkoxy group having 1 to 18 carbon atoms or a halogen atom, a=0, 1, 2, or 3, b=0, 1, 2, or 3, and a+b=1, 2, or 3, and the disilazane is represented by (R １１ R １２ R １３ )SiNHSi(R １４ R １５ R １６ ) and R １１ , R １２ , R １３ , R１４ , R １５ and R １６ is an independently selectable hydrocarbon group having 1 to 18 carbon atoms or a hydrogen atom.

[0060] The silica filler obtained as described above is preferably further subjected to dry or wet sieving or inertial classification to remove coarse particles of 5 μm, 10 μm, 20 μm or more from the spherical silica powder filler.

[0061] The content of the silica filler (B) is preferably 10 parts by mass or more and 400 parts by mass or less, and more preferably 30 parts by mass or more and 150 parts by mass or less, relative to 100 parts by mass of the resin component containing the polyfunctional vinyl aromatic copolymer (A). By including the silica filler (B) in such an amount, it is believed that the resin composition of this embodiment can more reliably obtain excellent fluidity and adhesion.

[0062] The resin composition of this embodiment may contain an inorganic filler other than the silica filler (B) as long as it does not impair the effects of the present invention. The inorganic filler other than the silica filler (B) is not particularly limited as long as it can be used as an inorganic filler contained in the resin composition. Specific examples include metal oxide fillers such as alumina filler, titanium oxide filler, magnesium oxide filler, and mica filler, metal hydroxide fillers such as aluminum hydroxide filler and magnesium hydroxide filler, talc filler, aluminum borate filler, barium sulfate filler, aluminum nitride filler, silicon nitride filler, magnesium carbonate filler such as anhydrous magnesium carbonate filler, boron nitride filler, calcium carbonate filler, etc. Among these, anhydrous magnesium carbonate filler, alumina filler, and silicon nitride filler are preferred.

[0063] <Silane coupling agent (C)> The resin composition of this embodiment may contain a silane coupling agent (C) in addition to the above-mentioned polyfunctional vinyl aromatic copolymer (A) and silica filler (B).It is thought that this improves the adhesion between the polyfunctional vinyl aromatic copolymer (A) and the silica filler (B).The silane coupling agent (C) referred to here may be the silane coupling agent used for the surface treatment of the silica filler (B), or the silane coupling agent that is added to the resin composition separately from the surface-treated filler may be used.

[0064] As the silane coupling agent (C), it is preferable to use a silane coupling agent having a functional group containing a carbon-carbon unsaturated bond. Examples include silane coupling agents having at least one functional group selected from the group consisting of a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, and a phenylamino group. That is, the silane coupling agent has at least one reactive functional group selected from the group consisting of a vinyl group, a styryl group, a methacryloyl group, an acryloyl group, and a phenylamino group, and further includes compounds having a hydrolyzable group such as a methoxy group or an ethoxy group. These can be used alone or in combination of two or more.

[0065] More specific examples of the silane coupling agent (C) include those having a vinyl group, such as vinyltriethoxysilane and vinyltrimethoxysilane. Examples of the silane coupling agent having a styryl group include p-styryltrimethoxysilane and p-styryltriethoxysilane. Examples of the silane coupling agent having a methacryloyl group include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylethyldiethoxysilane. Examples of the silane coupling agent having an acryloyl group include 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.

[0066] The content of the silane coupling agent (C) is preferably 0.1 parts by mass or more and 2 parts by mass or less, and more preferably 0.3 parts by mass or more and 1 part by mass or less, per 100 parts by mass of the resin component containing the polyfunctional vinyl aromatic copolymer (A), whether it is added externally (added separately from the surface treatment of the silica filler (B)) or used in the surface treatment of the silica filler (B).

[0067] <Other Thermosetting Compounds (D)> The resin composition of the present embodiment may further contain a thermosetting compound (D) other than the polyfunctional vinyl aromatic copolymer (A). The inclusion of such a thermosetting compound (D) is considered to have advantages such as improved heat resistance, an increase in glass transition temperature, and an improvement in copper foil peel strength.

[0068] Specific examples of the thermosetting compound (D) include at least one compound selected from the group consisting of modified polyphenylene ethers having carbon-carbon unsaturated groups, acenaphthylene compounds, maleimide compounds, and polyfunctional hydrocarbon compounds having carbon-carbon unsaturated groups other than the polyfunctional vinyl aromatic copolymer (A). These compounds may be used alone or in combination of two or more.

[0069] The modified polyphenylene ether is a polyphenylene ether compound having a reactive carbon-carbon unsaturated double bond. For example, since it is preferable to use a terminal-modified polyphenylene ether compound that can exhibit excellent low dielectric properties when cured, it is preferable to use a modified polyphenylene ether compound that is terminal-modified with a substituent having a carbon-carbon unsaturated double bond.

[0070] Examples of the substituent having a carbon-carbon unsaturated double bond include groups having a styrene structure or a (meth)acrylate structure, such as those represented by the following formula (6) or (7).

[0071]

[0072]

[0073] In formula (7), R Ｘ represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0074] More specific examples of the substituent include vinylbenzyl groups (ethenylbenzyl groups) such as p-ethenylbenzyl and m-ethenylbenzyl groups, vinylphenyl groups, acrylate groups, and methacrylate groups.

[0075] It is believed that by using such a modified polyphenylene ether compound, it is possible to maintain low dielectric properties such as a low dielectric constant and a low dielectric loss tangent, and excellent heat resistance, while also improving high Tg and adhesion.

[0076] The modified polyphenylene ether compounds may be used singly or in combination of two or more.

[0077] In the present embodiment, the weight-average molecular weight (Mw) of the modified polyphenylene ether compound used as the thermosetting resin is not particularly limited, but is preferably, for example, 1,000 to 5,000, and more preferably 1,000 to 4,000. The weight-average molecular weight may be measured using a general molecular weight measurement method, and specific examples include values ​​measured using gel permeation chromatography (GPC). Furthermore, when the modified polyphenylene ether compound has repeating units (s, m, n) in the molecule, it is preferable that these repeating units have values ​​such that the weight-average molecular weight of the modified polyphenylene ether compound falls within the above range.

[0078] When the weight-average molecular weight of the modified polyphenylene ether compound is within this range, it exhibits the excellent low dielectric properties of the polyphenylene ether skeleton, and the cured product not only exhibits excellent heat resistance but also exhibits excellent moldability. This is believed to be due to the following reasons. Compared to ordinary polyphenylene ethers, if the weight-average molecular weight is within the above-mentioned range, the compound has a relatively low molecular weight, which tends to result in reduced heat resistance of the cured product. In this regard, the modified polyphenylene ether compound according to this embodiment has a styrene structure or a (meth)acrylate structure at its terminal, which is believed to have high reactivity and to produce a cured product with sufficiently high heat resistance. Furthermore, when the weight-average molecular weight of the modified polyphenylene ether compound is within this range, it has a high molecular weight compared to styrene or divinylbenzene, but a relatively low molecular weight compared to ordinary polyphenylene ether, which is believed to result in excellent moldability. Therefore, it is believed that such modified polyphenylene ether compounds not only exhibit excellent heat resistance of the cured product but also exhibit excellent moldability.

[0079] Furthermore, in the modified polyphenylene ether compound used as the thermosetting resin in this embodiment, the average number of the substituents (number of terminal functional groups) at the molecular terminals per molecule of the modified polyphenylene ether is not particularly limited. Specifically, it is preferably 1 to 5, and more preferably 1 to 3. If the number of terminal functional groups is too small, it tends to be difficult to obtain a cured product with sufficient heat resistance. Furthermore, if the number of terminal functional groups is too large, the reactivity becomes too high, which may result in problems such as reduced shelf life and reduced fluidity of the resin composition. In other words, when such modified polyphenylene ether is used, there is a risk of moldability problems such as poor molding, such as the generation of voids during multilayer molding, due to insufficient fluidity.

[0080] The number of terminal functional groups of a modified polyphenylene ether compound may be, for example, a numerical value representing the average number of the substituents per molecule of all modified polyphenylene ether compounds present in 1 mole of the modified polyphenylene ether compound. The number of terminal functional groups can be measured, for example, by measuring the number of hydroxyl groups remaining in the obtained modified polyphenylene ether compound and calculating the difference from the number of hydroxyl groups in the polyphenylene ether before modification. This difference from the number of hydroxyl groups in the polyphenylene ether before modification is the number of terminal functional groups. The number of hydroxyl groups remaining in the modified polyphenylene ether compound can be measured by adding a quaternary ammonium salt (tetraethylammonium hydroxide) that associates with hydroxyl groups to a solution of the modified polyphenylene ether compound and measuring the UV absorbance of the resulting mixed solution.

[0081] The polyphenylene ether compound used in the resin composition of this embodiment can be synthesized by a known method, or a commercially available product can be used. Examples of commercially available products include "OPE-2st 1200" and "OPE-2st 2200" manufactured by Mitsubishi Gas Chemical Company, Inc., and "SA9000" manufactured by SABIC Innovative Plastics.

[0082] In the present embodiment, the acenaphthylene compound can be any compound having an acenaphthylene structure in the molecule, and specific examples thereof include acenaphthylene, alkylacenaphthylenes, halogenated acenaphthylenes, and phenylacenaphthylenes.

[0083] Examples of the alkylacenaphthylenes include 1-methylacenaphthylene, 3-methylacenaphthylene, 4-methylacenaphthylene, 5-methylacenaphthylene, 1-ethylacenaphthylene, 3-ethylacenaphthylene, 4-ethylacenaphthylene, 5-ethylacenaphthylene, etc. Examples of the halogenated acenaphthylenes include 1-chloroacenaphthylene, 3-chloroacenaphthylene, 4-chloroacenaphthylene, 5-chloroacenaphthylene, 1-bromoacenaphthylene, 3-bromoacenaphthylene, 4-bromoacenaphthylene, 5-bromoacenaphthylene, etc. Examples of the phenylacenaphthylenes include 1-phenylacenaphthylene, 3-phenylacenaphthylene, 4-phenylacenaphthylene, 5-phenylacenaphthylene, etc. The acenaphthylene compound may be a monofunctional acenaphthylene compound having one acenaphthylene structure in the molecule, as described above, or a polyfunctional acenaphthylene compound having two or more acenaphthylene structures in the molecule.

[0084] The maleimide compound usable in this embodiment is not particularly limited as long as it has a maleimide group in the molecule. Specific examples of the maleimide compound include monofunctional maleimide compounds having one maleimide group in the molecule, polyfunctional maleimide compounds having two or more maleimide groups in the molecule, and modified maleimide compounds. Examples of the polyfunctional maleimide compound include aromatic maleimide compounds containing an aromatic group in the molecule, imide group-containing maleimide compounds having an imide group in the molecule, aliphatic maleimide compounds containing a long-chain alkyl group in the molecule, and maleimide compounds having an arylene structure in the molecule bonded in a meta-oriented manner. Examples of the modified maleimide compound include modified maleimide compounds in which a portion of the molecule is modified with an amine compound, modified maleimide compounds in which a portion of the molecule is modified with a silicone compound, and modified maleimide compounds in which a portion of the molecule is modified with both an amine compound and a silicone compound.

[0085] The maleimide compound used in the present embodiment may be a commercially available product, and examples thereof include the solids in MIR-3000-70MT and MIR-5000-60T manufactured by Nippon Kayaku Co., Ltd., BMI-4000, BMI-2300, and BMI-TMH manufactured by Daiwa Kasei Kogyo Co., Ltd., and BMI-689, BMI-1500, BMI-3000J, and BMI-5000 manufactured by Designer Molecules Inc.

[0086] The polyfunctional hydrocarbon compound having a carbon-carbon unsaturated group other than the polyfunctional vinyl aromatic copolymer (A) used in this embodiment is not particularly limited as long as it is a polyfunctional hydrocarbon compound having a carbon-carbon unsaturated group other than the polyfunctional vinyl aromatic copolymer (A). Specific examples include divinylbenzene, polybutadiene, styrene butadiene oligomer, cyclic olefin compounds such as ethylene propylene diene rubber (EPDM) and cycloolefin polymer (COP).

[0087] When the resin composition of this embodiment contains the thermosetting compound (D), the content thereof is preferably 10% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 50% by mass or less, based on the total amount of the resin components including the polyfunctional vinyl aromatic copolymer (A) and the thermosetting compound (D). The content ratio of the polyfunctional vinyl aromatic copolymer (A) to the thermosetting compound (D) is preferably 50:50 to 90:10, and more preferably 70:30 to 90:10, by mass.

[0088] <Other Components> The resin composition according to the present embodiment may contain components (other components) other than the above-described components, as necessary, within a range that does not impair the effects of the present invention. Examples of other components contained in the resin composition according to the present embodiment include catalysts such as reaction initiators and reaction accelerators, polymerization inhibitors, polymerization retarders, free radical compounds, flame retardants, flame retardant assistants, antifoaming agents, leveling agents, antioxidants, heat stabilizers, antistatic agents, UV absorbers, and additives such as dyes, pigments, dispersants, and lubricants.

[0089] As described above, the resin composition according to this embodiment may contain a reaction initiator (catalyst) and a reaction accelerator. The radical polymerization (curing) reaction of the resin composition may proceed even without a reaction initiator. However, depending on the process conditions, it may be difficult to raise the temperature high enough for curing to proceed, so a reaction initiator may be added. The reaction initiator and reaction accelerator are not particularly limited as long as they can accelerate the curing reaction of the resin composition. Specific examples include metal oxides, azo compounds, peroxides, imidazole compounds, phosphorus-based curing accelerators, and amine-based curing accelerators.

[0090] Specific examples of metal oxides include metal carboxylates. Examples of organic peroxides include α,α'-di(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, benzoyl peroxide, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, and azobisisobutyronitrile. Specific examples of azo compounds include 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(2-methylbutyronitrile). The above-mentioned reaction initiators may be used alone or in combination of two or more.

[0091] When the resin composition of the present embodiment contains the reaction initiator, the content thereof is not particularly limited, but is preferably, for example, about 0.1 to 5.0 parts by mass per 100 parts by mass of the resin component containing the polyfunctional vinyl aromatic copolymer (A).

[0092] (Prepreg, Resin-Coated Film, Metal-Clad Laminate, Wiring Board, and Resin-Coated Metal Foil) Next, a prepreg for wiring boards, a metal-clad laminate, a wiring board, and a resin-coated metal foil using the resin composition of this embodiment will be described.

[0093] 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment of the present invention. In the following description, the respective reference numerals represent: 1 prepreg, 2 resin composition or semi-cured resin composition, 3 fibrous substrate, 11 metal-clad laminate, 12 insulating layer, 13 metal foil, 14 wiring, 21 wiring board, 31 resin-coated metal foil, 32, 42 resin layer, 41 resin-coated film, and 43 support film.

[0094] As shown in Fig. 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. Examples of this prepreg 1 include those in which the fibrous base material 3 is present in the resin composition or a semi-cured product thereof 2. That is, this prepreg 1 comprises the resin composition or a semi-cured product thereof, and the fibrous base material 3 present in the resin composition or a semi-cured product thereof 2.

[0095] In this embodiment, the term "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 is 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 can be exemplified by the state between when the viscosity starts to increase and when the composition is completely cured.

[0096] 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 substrate, or a prepreg comprising the resin composition before curing (the resin composition in A stage) and a fibrous substrate. Specific examples include those in which a fibrous substrate is present in the resin composition. The resin composition or its semi-cured product may be obtained by heating and drying the resin composition.

[0097] The resin composition according to the present embodiment is often prepared in the form of a varnish and used as a resin varnish when producing the prepreg, or the resin-coated metal foil or metal-clad laminate described below. Such a resin varnish is prepared, for example, as follows.

[0098] First, each component soluble in an organic solvent, such as a resin component and a reaction initiator, is added to an organic solvent and dissolved. Heating may be performed as necessary. Then, an inorganic filler, such as silica filler (B), which is a component insoluble in an organic solvent, is added and dispersed using a ball mill, bead mill, planetary mixer, roll mill, or the like until a predetermined dispersion state is reached, thereby preparing a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves resin components, such as the polyfunctional vinyl aromatic copolymer (A) and other thermosetting compounds (D), and does not inhibit the curing reaction. Specific examples include toluene, methyl ethyl ketone, cyclohexanone, cyclopentanone, methylcyclohexane, dimethylformamide, and propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more.

[0099] As a method for producing the prepreg 1 of this embodiment using the varnish-like resin composition of this embodiment, for example, a method of impregnating the fibrous base material 3 with the resin composition 2 in the form of a resin varnish and then drying it can be mentioned.

[0100] Specific examples of fibrous substrates used in producing prepregs include glass cloth, aramid cloth, polyester cloth, LCP (liquid crystal polymer) nonwoven fabric, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. The use of glass cloth results in a laminate with excellent mechanical strength, and flattened glass cloth is particularly preferred. The glass cloth used in this embodiment is not particularly limited, but examples include low-dielectric-constant glass cloths such as E glass, S glass, NE glass, Q glass, and L glass. Flattening can be performed, for example, by continuously pressing the glass cloth with a press roll at an appropriate pressure to compress the yarns flat. The thickness of the fibrous substrate can generally be, for example, 0.01 to 0.3 mm.

[0101] The resin varnish (resin composition 2) is impregnated into the fibrous substrate 3 by immersion, coating, or the like. This impregnation can be repeated multiple times as necessary. In this case, it is also possible to repeat the impregnation using multiple resin varnishes with different compositions and concentrations, and to adjust the final composition (content ratio) and resin amount to the desired one.

[0102] The fibrous substrate 3 impregnated with the resin varnish (resin composition 2) is heated under desired heating conditions, for example, at a temperature of 80°C or higher and 180°C or lower for 1 minute or longer and 10 minutes or shorter. By heating, the solvent is volatilized from the varnish, reducing or removing the solvent, thereby obtaining a prepreg 1 in an uncured (A-stage) or semi-cured (B-stage) state.

[0103] 4, the resin-coated metal foil 31 of this embodiment has a configuration in which a resin layer 32 containing the above-mentioned resin composition or a semi-cured product of the resin composition is laminated with a metal foil 13. That is, the resin-coated metal foil of this embodiment may be a resin-coated metal foil comprising a resin layer containing the resin composition before curing (the resin composition in A stage) and a metal foil, or a resin-coated metal foil comprising a resin layer containing a semi-cured product of the resin composition (the resin composition in B stage) and a metal foil.

[0104] Examples of a method for producing such a resin-coated metal foil 31 include a method in which the resin composition in the form of a resin varnish as described above is applied to the surface of a metal foil 13 such as a copper foil, followed by drying. Examples of the application method include a bar coater, a comma coater, a die coater, a roll coater, a gravure coater, and the like.

[0105] As the metal foil 13, any metal foil that is used in metal-clad laminates, wiring boards, etc. can be used without any limitation, and examples thereof include copper foil and aluminum foil.

[0106] 5, the resin-coated film 41 of this embodiment has a configuration in which a resin layer 42 containing the above-mentioned resin composition or a semi-cured product of the resin composition is laminated on a film support substrate 43. That is, the resin-coated film of this embodiment may be a resin-coated film comprising the resin composition before curing (the resin composition in A stage) and a film support substrate, or may be a resin-coated film comprising a semi-cured product of the resin composition (the resin composition in B stage) and a film support substrate.

[0107] A method for producing such a resin-coated film 41 includes, for example, applying a resin varnish-like resin composition as described above to the surface of the film support substrate 43, and then evaporating the solvent from the varnish to reduce or remove the solvent, thereby obtaining a resin-coated film in a pre-cured (A stage) or semi-cured (B stage) state.

[0108] Examples of the film support substrate include electrically insulating films such as polyimide films, PET (polyethylene terephthalate) films, polyethylene naphthalate films, polyester films, polyparabanic acid films, polyether ether ketone films, polyphenylene sulfide films, aramid films, polycarbonate films, and polyarylate films.

[0109] In the resin-coated film and resin-coated metal foil of this embodiment, the resin composition or the semi-cured product thereof may be obtained by drying or heat-drying the resin composition, as in the prepreg described above.

[0110] The thickness of the metal foil 13 and the film support substrate 43 can be appropriately set depending on the desired purpose. For example, a metal foil 13 having a thickness of approximately 0.2 to 70 μm can be used. When the thickness of the metal foil is, for example, 10 μm or less, a carrier-attached copper foil having a release layer and a carrier for improved handling may be used. The resin varnish is applied to the metal foil 13 and the film support substrate 43 by coating, which can be repeated multiple times as needed. In addition, it is also possible to repeatedly apply multiple resin varnishes with different compositions and concentrations to adjust the final composition (content ratio) and resin amount to the desired level.

[0111] The drying or heating and drying conditions in the manufacturing method of the resin-coated metal foil 31 or the resin-coated film 41 are not particularly limited, but after applying a resin varnish-like resin composition to the metal foil 13 or the film support substrate 43, it is heated under the desired heating conditions, for example, at 50 to 180°C for about 0.1 to 10 minutes, to volatilize the solvent from the varnish and reduce or remove the solvent, thereby obtaining the resin-coated metal foil 31 or the resin-coated film 41 in a pre-cured (A stage) or semi-cured (B stage) state.

[0112] The resin-coated metal foil 31 or the resin-coated film 41 may be provided with a cover film or the like, as necessary. The provision of a cover film can prevent the inclusion of foreign matter, etc. The cover film is not particularly limited as long as it can be peeled off without damaging the shape of the resin composition. For example, a polyolefin film, a polyester film, a TPX film, a film formed by providing a release agent layer on any of these films, or even paper formed by laminating any of these films onto a paper substrate can be used.

[0113] 2, the metal-clad laminate 11 of this embodiment is characterized by having an insulating layer 12 containing a cured product of the above-described resin composition or a cured product of the above-described prepreg, and a metal foil 13. Note that the metal foil 13 used in the metal-clad laminate 11 may be the same as the metal foil 13 described above.

[0114] The metal-clad laminate 11 of this embodiment can also be produced using the resin-coated metal foil 31 or resin-coated film 41 described above.

[0115] A method for producing a metal-clad laminate using the prepreg 1, resin-coated metal foil 31, or resin-coated film 41 obtained as described above involves stacking one or more prepregs 1, resin-coated metal foils 31, or resin-coated films 41, and then stacking a metal foil 13 such as copper foil on both sides or one side of the prepreg 1, and then heat-pressure molding the stack to form an integrated laminate, thereby producing a double-sided or single-sided metal foil-clad laminate. The heat-pressure conditions can be set appropriately depending on the thickness of the laminate to be produced, the type of resin composition, and the like, but can be, for example, a temperature of 170 to 230°C, a pressure of 1.5 to 5.0 MPa, and a time of 60 to 150 minutes.

[0116] Alternatively, the metal-clad laminate 11 may be produced by forming a film-like resin composition on the metal foil 13 and then applying heat and pressure, without using the prepreg 1 or the like.

[0117] As shown in FIG. 3, the wiring board 21 of this embodiment has an insulating layer 12 containing the cured product of the resin composition or the cured product of the prepreg, and wiring 14 .

[0118] The resin composition of this embodiment is suitable for use as a material for the insulating layer of a wiring board. For example, a method for producing a wiring board 21 includes etching the metal foil 13 on the surface of the metal-clad laminate 11 obtained above to form a circuit (wiring), thereby obtaining a wiring board 21 having a conductor pattern (wiring 14) as a circuit on the surface of the laminate. In addition to the above-described methods, examples of the circuit formation method include circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0119] The prepreg, resin-coated film, and resin-coated metal foil obtained using the resin composition of this embodiment have excellent low dielectric properties, fluidity, and adhesion (particularly interlayer peel strength) when cured, making them extremely useful for industrial applications. Furthermore, metal-clad laminates and wiring boards obtained by curing these materials also have the same excellent properties.

[0120] This specification discloses various aspects of the technology as described above, but the main technologies among them are summarized below.

[0121] The resin composition according to a first aspect of the present invention comprises a polyfunctional vinyl aromatic copolymer (A) and a silica filler (B), and is characterized in that the particle size distribution of the silica filler (B) has a volume-based cumulative 10% particle size (D10) of 0.7 μm or more, a volume-based cumulative 50% particle size (D50) of 0.9 μm or more and 4.0 μm or less, and a volume-based cumulative 90% particle size (D90) of 4.5 μm or less.

[0122] The resin composition according to the second aspect of the present invention is the resin composition according to the first aspect, which further comprises a silane coupling agent (C) having a functional group containing a carbon-carbon unsaturated bond.

[0123] A resin composition according to a third aspect of the present invention is the resin composition of the first or second aspect, wherein the functional group includes at least one selected from a methacryl group and a styrene group.

[0124] 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, wherein the polyfunctional vinyl aromatic copolymer (A) contains a repeating unit (a1) derived from a divinyl aromatic copolymer and a repeating unit (a2) derived from a monovinyl aromatic compound.

[0125] 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, wherein the content of the silica filler (B) is 10 to 400 parts by mass per 100 parts by mass of the resin component including the polyfunctional vinyl aromatic copolymer (A).

[0126] The 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, wherein the content of the polyfunctional vinyl aromatic copolymer (A) is 50 to 100 mass% based on the total amount of the resin components including the polyfunctional vinyl aromatic copolymer (A).

[0127] A prepreg according to a seventh aspect of the present invention comprises the resin composition of any one of the first to sixth aspects or a semi-cured product of the resin composition, and a fibrous base material.

[0128] A resin-coated film according to an eighth aspect of the present invention comprises a resin layer containing the resin composition of any one of the first to sixth aspects or a semi-cured product of the resin composition, and a support film.

[0129] A resin-coated metal foil according to a ninth aspect of the present invention comprises a resin layer containing the resin composition of any one of the first to sixth aspects or a semi-cured product of the resin composition, and a metal foil.

[0130] A metal-clad laminate according to a tenth aspect of the present invention has an insulating layer containing a cured product of the resin composition according to any one of the first to sixth aspects or a cured product of the prepreg according to the seventh aspect, and a metal foil.

[0131] A wiring board according to an eleventh aspect of the present invention has an insulating layer including a cured product of the resin composition according to any one of the first to sixth aspects or a cured product of the prepreg according to the seventh aspect, and wiring.

[0132] 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.

[0133] First, the components used in preparing the resin composition in this example will be described.

[0134] <Multifunctional vinyl aromatic polymer (A-1)> A multifunctional vinyl aromatic polymer was obtained based on the following method: 2.25 mol (292.9 g) of divinylbenzene, 1.32 mol (172.0 g) of ethylvinylbenzene, 11.43 mol (1190.3 g) of styrene, and 15.0 mol (1532.0 g) of n-propyl acetate were charged into a 5.0 L reactor, and 600 mmol of a diethyl ether complex of boron trifluoride was added at 70 ° C., followed by a reaction for 4 hours. Thereafter, in order to terminate the reaction, an aqueous sodium bicarbonate solution was added to the resulting reaction solution, and the oil layer was washed three times with pure water, and the mixture was subjected to vacuum devolatilization at 60 ° C. to recover the solid. The resulting solid was weighed, and it was confirmed that 860.8 g was obtained.

[0135] The molecular weight and molecular weight distribution of the obtained solid (polymer) were measured using GPC (HLC-8120GPC manufactured by Tosoh Corporation) with tetrahydrofuran as a solvent, a flow rate of 1.0 ml / min, a column temperature of 38°C, and a calibration curve with monodisperse polystyrene. As a result, the number average molecular weight Mn of the obtained solid was 2060, the weight average molecular weight Mw was 3070, and Mw / Mn was 14.9.

[0136] The structure of the obtained solid (polymer) was analyzed using a JNM-LA600 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. １３ C-NMR and １ The measurement was carried out by H-NMR analysis. １ was used, and the resonance line of tetramethylsilane was used as an internal standard. １３ C-NMR and １ The amount of a specific structural unit introduced was calculated from the data on the total amount of each structural unit introduced into the copolymer obtained by GC analysis in addition to the H-NMR measurement results, and the amount of pendant vinyl group units contained in the polyfunctional vinyl aromatic copolymer was calculated from the amount of the specific structural unit introduced at the terminal and the number average molecular weight obtained by the GPC measurement.

[0137] The resulting solid was subjected to the above-mentioned １３ C-NMR and １By performing H-NMR analysis, resonance lines derived from each monomer unit were observed. Furthermore, based on the results of NMR measurement and GC analysis, it was found that this solid was the polyfunctional vinyl aromatic copolymer. Based on the results of NMR measurement and GC analysis, the constituent units of this polyfunctional vinyl aromatic copolymer were calculated as follows: 20.9 mol % (24.3 wt %) of structural units (a1-1) derived from divinylbenzene, 70.0 mol % (65.0 wt %) of structural units (a1-2) derived from styrene, 9.1 mol % (10.7 wt %) of structural units (a1-3) derived from ethylvinylbenzene, and 16.7 mol % (18.5 wt %) of structural units (a1-1-1) having residual vinyl groups derived from divinylbenzene.

[0138] <Thermosetting compound (D): Modified polyphenylene ether compound> Modified PPE: polyphenylene ether compound having a methacryloyl group at its terminal ("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)

[0139] <Silane Coupling Agent (C)> Silane coupling agent: 3-methacryloxypropyltrimethoxysilane (a silane coupling agent having a methacryl group in the molecule, "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.)

[0140] <Reaction initiator> Peroxide 1: α,α'-di(t-butylperoxy)diisopropylbenzene ("Perbutyl P (PBP)" manufactured by NOF Corporation) Peroxide 2: dicumyl peroxide ("Percumyl D" manufactured by NOF Corporation) Azo compound: 2,2'azobis(2,4,4-trimethylpentane ("VR-110" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0141] <Silica fillers> Silica filler 1 (manufactured by Zhejiang Sanshiji New Materials Technology Co., Ltd., "EQ0610-SMC") Silica filler 2 (manufactured by Zhejiang Sanshiji New Materials Technology Co., Ltd., "EQ1010-SMC") Silica filler 3 (manufactured by Zhejiang Sanshiji New Materials Technology Co., Ltd., "EQ2410-SMC") Silica filler 4 (manufactured by Zhejiang Sanshiji New Materials Technology Co., Ltd., "EQ5010-SMC") Silica filler 5 (spherical fused silica, manufactured by Denka Company, Ltd., "FB-3SDC") Silica filler 6 (spherical fused silica, manufactured by Denka Company, Ltd., "FB-7SDC")

[0142] Examples 1 to 8 and Comparative Examples 1 to 5 Preparation Method (Resin Varnish) First, the resin components were added to a toluene solvent in the blending ratios (parts by mass) shown in Table 1 so that the solids concentration was 45% by mass, and mixed. The resulting mixture was stirred for 60 minutes. Thereafter, an inorganic filler (silica filler) was added to the resulting mixture, and after pre-dispersion using a stirrer, the filler was dispersed using a bead mill. This resulted in a varnish-like resin composition (varnish).

[0143] (Preparation of Evaluation Board) A prepreg and an evaluation board (metal-clad laminate) were obtained as follows.

[0144] First, a fibrous substrate (glass cloth: #1078 type, L2 glass manufactured by Asahi Kasei Corporation) was impregnated with the obtained varnish, and then heated and dried at 120°C for 3 minutes to produce a prepreg with a thickness of 75 µm. At this time, the content of the components constituting the resin composition by the curing reaction relative to the prepreg (resin content) was adjusted to be approximately 66% by mass.

[0145] Next, an evaluation substrate (metal-clad laminate) was obtained as follows.

[0146] Two or ten sheets of each prepreg obtained were stacked, and copper foil (T4X-SV-18, manufactured by Fukuda Metal Foil & Powder Co., Ltd., copper foil thickness: 18 μm) was placed on both sides. This was used as a pressure body, and was heated to a temperature of 220°C at a temperature increase rate of 3°C / min, and then heated and pressurized at 220°C for 120 minutes under a pressure of 3 MPa, to obtain an evaluation substrate (metal-clad laminate) with copper foil bonded to both sides and a resin layer thickness of approximately 150 μm.

[0147] Using the evaluation substrate (metal-clad laminate) prepared as described above, an evaluation test was carried out by the following method.

[0148] <Evaluation Test 1> [Particle Size Distribution of Silica Filler] First, the particle size distribution of the silica filler used in each example and comparative example was determined by measurement using a laser diffraction / scattering particle size distribution measuring device SALD-2300 (Shimadzu Corporation). The specifications of the device are as follows: Measurement principle: Mie scattering theory Measurement range: 0.017 μm to 2500 μm Light source: semiconductor laser (wavelength 680 nm, output 3 mW) Light receiving unit: 78-element modified concentric sensor, side sensor (1 element), rear sensor (5 elements) totaling 84 elements of optical sensor Refractive index: 1.450-0.000i Cell material: quartz glass

[0149] The particle size distribution measurement conditions were as follows: Each measurement sample was placed in a flow cell via a sample bath using toluene as a dispersion solvent, and laser diffraction / scattering particle size distribution measurement was carried out in a stirred state.

[0150] The particle size distribution was analyzed and calculated using the analysis software WingSALDII attached to the SALD-2300. Then, the D50 and D90 of each were determined.

[0151] (Dielectric Property 1: Dielectric Loss Tangent (Df)) An unclad plate obtained by etching the copper foil from the 150 μm-thick evaluation substrate (metal-clad laminate) was used as a test specimen, and the relative permittivity and dielectric loss tangent at 10 GHz were measured by a cavity resonator perturbation method. Specifically, the dielectric loss tangent of the evaluation substrate at 10 GHz was measured using a network analyzer (N5230A manufactured by Keysight Technologies, Inc.). In this test, a Df of 0.0014 or less was considered to be a pass.

[0152] (Interlayer Peel Strength) The insulating layer (prepreg) on ​​the top surface of the evaluation substrate (metal-clad laminate) was peeled off at a rate of 50 mm / min using a tensile tester (i.e., the insulating layer on the top surface was peeled off from the insulating layer underneath), and the peel strength (N / mm) at this time was measured. This peel strength is the interlayer peel strength. It was found that the higher this peel strength, the higher the interlayer adhesion, and if the measured interlayer peel strength was 0.32 N / mm or more, it was determined to be acceptable.

[0153] (Fluidity: Glinis Value) The Glinis value is a numerical value obtained by performing a resin fluidity evaluation test (Glinis evaluation). First, the pre-molded prepreg was cut into 10 cm squares and four sheets were stacked to prepare a sample, and its weight was measured. Next, this sample was molded at a temperature of 170°C and a pressure of 1.4 MPa, and then cut into a sample size of 70.7 cm square and measured again. Then, based on the obtained value, the Glinis value was calculated using the following formula: [{(weight of sample before molding - weight of sample after molding x 2) / (weight of sample before molding)} x 100]. In this test, a Glinis value of 2.8 or more was considered to be a pass.

[0154] The results are shown in Table 1.

[0155]

[0156] (Discussion) As is clear from the results shown in Table 1, it was confirmed that the resin composition of the present invention can produce cured products having low dielectric properties (Df) and excellent fluidity and interlayer peel strength (adhesion). In contrast, Comparative Examples 1 to 4, which used resin compositions containing silica fillers that do not satisfy the requirements of the present invention, resulted in poor results in at least one (or both) of interlayer peel strength and fluidity. Furthermore, Comparative Example 5, which did not contain the polyfunctional vinyl aromatic copolymer (A), was unable to achieve sufficient low dielectric properties or interlayer peel strength.

[0157] <Evaluation Test 2> The evaluation boards of Examples 1 to 8 were further subjected to the following test.

[0158] (Dielectric Property 2: Dielectric Constant (Dk)) An unclad board obtained by removing the copper foil from an evaluation substrate (metal-clad laminate) by etching 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 of the evaluation substrate at 10 GHz was measured using a network analyzer (N5230A manufactured by Keysight Technologies, Inc.). In this test, a Dk of 3.3 or less was considered to be a pass.

[0159] (Copper Foil Peel Strength) The copper foil was peeled from the evaluation substrate (metal-clad laminate), and the peel strength at this time was measured in accordance with JIS C 6481 (1996). Specifically, the evaluation substrate was made 10 mm wide and long, and the copper foil was peeled at a rate of 50 mm / min using a tensile tester, and the peel strength (N / mm) at this time was measured. This peel strength is the copper foil peel strength, and the higher this is, the higher the adhesion of the metal foil (copper foil). In this test, if the measured copper foil peel strength was more than 0.20 N / mm, it was determined to be acceptable.

[0160] The results are shown in Table 2.

[0161]

[0162] (Discussion) From the results in Table 2, it was confirmed that in the Examples using the resin compositions of the present invention, in addition to the results of Evaluation Test 1, they also had excellent low dielectric properties (Dk) and copper foil peel strength.

[0163] This application is based on Japanese Patent Application No. 2023-222738 filed on December 28, 2023, the contents of which are incorporated herein by reference.

[0164] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments with reference to specific examples, drawings, etc., but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-described embodiments. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims.

[0165] The present invention has wide industrial applicability in technical fields related to electronic materials, electronic devices, optical devices, and the like.

Claims

1. A resin composition comprising a polyfunctional vinyl aromatic copolymer (A) and a silica filler (B), wherein in the particle size distribution of the silica filler (B), the volume-based cumulative 10% particle size (D10) is 0.7 μm or more, the volume-based cumulative 50% particle size (D50) is 0.9 μm or more and 4.0 μm or less, and the volume-based cumulative 90% particle size (D90) is 4.5 μm or less.

2. The resin composition according to claim 1, comprising a silane coupling agent (C) having a functional group containing a carbon-carbon unsaturated bond.

3. The resin composition according to claim 2, wherein the functional group contains at least one selected from a methacryl group and a styrene group.

4. The resin composition according to claim 1, wherein the polyfunctional vinyl aromatic copolymer (A) contains a repeating unit (a1) derived from a divinyl aromatic copolymer and a repeating unit (a2) derived from a monovinyl aromatic compound.

5. The resin composition according to claim 1, wherein the content of the silica filler (B) is 10 to 400 parts by mass with respect to 100 parts by mass of the resin component containing the polyfunctional vinyl aromatic copolymer (A).

6. The resin composition according to claim 1, wherein the content of the polyfunctional vinyl aromatic copolymer (A) is 50 to 100% by mass with respect to the total amount of the resin component containing the polyfunctional vinyl aromatic copolymer (A).

7. A prepreg having the resin composition according to any one of claims 1 to 6 or a semi-cured product of the resin composition and a fibrous substrate.

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

9. A metal-clad laminate having a resin layer containing the resin composition according to any one of claims 1 to 6 or a semi-cured product of the resin composition and a metal foil.

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

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

13. A wiring board having an insulating layer containing a cured product of the prepreg according to claim 6 and a wiring.

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