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

Abstract

The present disclosure addresses the problem of providing a resin composition having both satisfactory moldability and tracking resistance. The resin composition comprises epoxy resins (A), a phenol resin (B), and inorganic fillers (C). The epoxy resins (A) comprise a dicyclopentadiene-type epoxy resin (A1) and a trisphenolmethane-type epoxy resin (A2). The inorganic fillers (C) comprise a first inorganic filler (C1), which has a first peak in an examination for volume-based particle size distribution, and a second inorganic filler (C2), which has a second peak that shows a smaller particle diameter than the first peak. The first inorganic filler (C1) and the second inorganic filler (C2) are each at least one filler selected from the group consisting of aluminum hydroxide fillers, boehmite fillers, magnesium hydroxide fillers, dawsonite fillers, calcium aluminate hydrate fillers, calcium borate fillers, and zinc borate fillers.

Description

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

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

[0002] Patent Document 1 discloses a phosphorus-containing epoxy resin composition. This phosphorus-containing epoxy resin composition contains a phosphorus-containing epoxy resin (A) and a curing agent, and in an epoxy resin composition (a) having a phosphorus content of 1.22 to 4% by weight, the phosphorus-containing epoxy resin (A) is an organic phosphorus compound (b) having one active hydrogen bonded to a phosphorus atom with respect to 1 mol of a quinone compound. A phosphorus-containing organic compound (B) obtained by reacting in a range of 1.01 mol to less than 2 mol, and at least one epoxy resin (C) selected from General Formula 1, General Formula 2, and General Formula 3 is reacted so as to contain 20% to 45% by weight.

[0003] However, the resin composition of Patent Document 1 has a problem that it is difficult to achieve both good moldability and tracking resistance.

[0004] Japanese Patent No. 4588834

[0005] An object of the present disclosure is to provide a resin composition, prepreg, resin film, metal foil with resin, metal-clad laminate, and wiring board that achieve both good moldability and tracking resistance.

[0006] A resin composition according to one aspect of the present disclosure contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C). The epoxy resin (A) comprises a dicyclopentadiene type epoxy resin (A1) and a trisphenolmethane type epoxy resin (A2). The inorganic filler (C) has at least a first peak and a second peak showing a particle size smaller than the first peak in a volume-based particle size distribution measurement measured by laser diffraction-scattering. The inorganic filler (C) comprises a first inorganic filler (C1) that gives the first peak and a second inorganic filler (C2) that gives the second peak. The first inorganic filler (C1) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler. The second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler.

[0007] A prepreg according to one aspect of the present disclosure comprises the resin composition or a semi-cured product of the resin composition and a fibrous substrate.

[0008] A resin-coated film according to one aspect of the present disclosure comprises a resin layer containing the resin composition or a semi-cured product of the resin composition, and a support film.

[0009] A resin-coated metal foil according to one aspect of the present disclosure comprises a resin layer containing the resin composition or a semi-cured product of the resin composition, and a metal foil.

[0010] A metal-clad laminate according to one aspect of the present disclosure comprises an insulating layer containing a cured product of the resin composition and a metal layer.

[0011] A metal-clad laminate according to one aspect of the present disclosure comprises an insulating layer containing a cured prepreg and a metal layer.

[0012] A wiring board according to one aspect of the present disclosure comprises an insulating layer containing a cured product of the resin composition, and wiring.

[0013] A wiring board according to one aspect of the present disclosure comprises an insulating layer containing a cured prepreg and wiring.

[0014] Figure 1 is a schematic cross-sectional view showing a prepreg according to one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view showing a resin-coated film according to one embodiment of the present disclosure. Figure 3 is a schematic cross-sectional view showing a resin-coated metal foil according to one embodiment of the present disclosure. Figure 4 is a schematic cross-sectional view showing a metal-clad laminate according to one embodiment of the present disclosure. Figure 5 is a schematic cross-sectional view showing a wiring board according to one embodiment of the present disclosure.

[0015] 1. Overview The resin composition of this disclosure contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C). The epoxy resin (A) includes a dicyclopentadiene type epoxy resin (A1) and a trisphenolmethane type epoxy resin (A2). The inorganic filler (C) has at least a first peak and a second peak showing a particle size smaller than the first peak in a volume-based particle size distribution measurement measured by laser diffraction-scattering. The inorganic filler (C) includes a first inorganic filler (C1) that gives the first peak and a second inorganic filler (C2) that gives the second peak. The first inorganic filler (C1) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler. The second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler.

[0016] Because the resin composition has the above-described characteristics, it achieves the effect of achieving both good moldability and tracking resistance. Specifically, the resin composition contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C), where the epoxy resin (A) includes a dicyclopentadiene type epoxy resin (A1) and a trisphenolmethane type epoxy resin (A2), and the inorganic filler (C) includes at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler, so the resin composition has good tracking resistance. Furthermore, because the inorganic filler (C) includes a first inorganic filler (C1) that gives a first peak and a second inorganic filler (C2) that gives a second peak, it has good moldability.

[0017] In this disclosure, the volume-based particle size distribution measured by laser diffraction and scattering may simply be referred to as the particle size distribution. Furthermore, the average particle diameter refers to the 50% (D50) cumulative value of the volume-based particle size distribution measured by laser diffraction and scattering.

[0018] 2. The resin composition, prepreg 1, resin-coated film 2, resin-coated metal foil 3, metal-clad laminate 4, and wiring board 5 according to detailed embodiments will be described below.

[0019] (1) Resin composition The resin composition contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C). The resin composition may further contain additives.

[0020] (1.1) Components <Epoxy Resin> The resin composition contains epoxy resin (A) as described above. Epoxy resin (A) comprises dicyclopentadiene type epoxy resin (A1) and trisphenolmethane type epoxy resin (A2). The inclusion of dicyclopentadiene type epoxy resin (A1) in epoxy resin (A) improves the tracking resistance of the cured product. The inclusion of trisphenolmethane type epoxy resin (A2) in epoxy resin (A) improves the glass transition temperature and heat resistance.

[0021] The concentration of hydrolyzable chlorine in epoxy resin (A) is preferably 300 ppm or less, and more preferably 50 ppm or less. If the concentration of hydrolyzable chlorine in epoxy resin (A) is 300 ppm or less, the amount of chloride ions generated in the presence of water can be reduced, and thus the occurrence of ion migration can be suppressed. The method for measuring the concentration of hydrolyzable chlorine is not particularly limited, but examples include ion chromatography.

[0022] Here, ion migration includes CAF (Conductive Anodic Filament). CAF is the deposition of metal ions eluted from the anode, mainly at the boundary between the resin and the fibrous substrate within the substrate layer. CAF is a phenomenon in which metal ions generated by the ionization of some of the metal in the inner layer circuit precipitate in other areas, and is likely to occur, for example, at the boundary between the fibrous substrate and the resin that is close to both the conductive metal that becomes the anode and cathode, as shown in part X of Figure 5.

[0023] Dicyclopentadiene-type epoxy resin (A1) is an epoxy resin that has a dicyclopentadiene skeleton in its molecule. Since the dicyclopentadiene skeleton does not contain aromatic rings, the proportion of aromatic rings in dicyclopentadiene-type epoxy resin (A1) is lower than in commonly used epoxy resins such as bisphenol A-type epoxy resin. When the proportion of aromatic rings in the molecule increases, the decomposition temperature rises and carbonization becomes more likely, thus increasing the possibility of tracking. Therefore, by using dicyclopentadiene-type epoxy resin (A1) with a low proportion of aromatic rings, the tracking resistance of the cured product can be improved.

[0024] The content of dicyclopentadiene-type epoxy resin (A1) is preferably 10% by mass or more, and more preferably 25% by mass or more, relative to the total amount of epoxy resin (A) and phenol resin (B). The content of dicyclopentadiene-type epoxy resin (A1) is preferably 50% by mass or less, and more preferably 45% by mass or less, relative to the total amount of epoxy resin (A) and phenol resin (B). Within the above range, the tracking resistance of the cured product can be further improved.

[0025] The specific structure of the dicyclopentadiene-type epoxy resin (A1) is not particularly limited, but examples include the compound represented by formula (1).

[0026]

[0027] In equation (1), n ​​is an integer between 1 and 10, inclusive.

[0028] For example, commercially available dicyclopentadiene type epoxy resin (A1) can be used. Examples of commercially available products include HP-7200, HP-7200L, HP-7200H, HP-7200HH, and HP-7200HHH from DIC Corporation; and XD-1000 from Nippon Kayaku Co., Ltd.

[0029] Trisphenolmethane-type epoxy resin (A2) is an epoxy resin having a trisphenylmethane skeleton in its molecule. The inclusion of trisphenolmethane-type epoxy resin (A2) can improve the glass transition temperature and heat resistance of the cured product.

[0030] A specific example of the trisphenolmethane-type epoxy resin (A2) is the compound represented by formula (2).

[0031]

[0032] In formula (2), n is an integer between 1 and 10. The compound represented by formula (2) has a high proportion of epoxy groups in its molecule, which can improve the glass transition temperature and heat resistance of the cured product.

[0033] For the trisphenolmethane type epoxy resin (A2), commercially available products can be used, for example. Examples of commercially available products include HP-7241 and HP-7250 from DIC Corporation; and EPPN-501H, EPPN-501HY, and EPPN-502H from Nippon Kayaku Co., Ltd.

[0034] The mass ratio of dicyclopentadiene-type epoxy resin (A1) to trisphenolmethane-type epoxy resin (A2) is preferably 1:5 to 5:1, and more preferably 5:8 to 5:2. If the mass ratio of dicyclopentadiene-type epoxy resin (A1) to trisphenolmethane-type epoxy resin (A2) is within the above range, the occurrence of ion migration can be further suppressed and the tracking resistance of the cured product can be improved.

[0035] The epoxy resin (A) may further contain other epoxy resins different from the dicyclopentadiene-type epoxy resin (A1) and the trisphenolmethane-type epoxy resin (A2), as is necessary, as long as it does not impair the effects of the present disclosure.

[0036] <Phenolic Resin> As described above, the resin composition contains phenolic resin (B). Phenolic resin (B) has phenolic hydroxyl groups in its molecule. The inclusion of phenolic resin (B) can suppress the occurrence of ion migration and improve the glass transition temperature, heat resistance, and flame retardancy of the cured product.

[0037] The phenolic resin (B) is not particularly limited, but examples include biphenyl aralkyl type phenolic resin, phenyl aralkyl type phenolic resin, novolac type phenolic resin, cresol novolac type phenolic resin, bisphenol A novolac type phenolic resin, naphthalene type phenolic resin, tetrakisphenol type phenolic resin, and phosphorus atom-containing phenolic resins in which phosphorus atoms are contained in the above phenolic resin. The phenolic resin (B) contained in the resin composition may be one type or two or more types.

[0038] Phenolic resin (B) preferably contains a polyfunctional phenolic resin. The polyfunctional phenolic resin is a compound having an average of two or more phenolic hydroxyl groups in one molecule. The polyfunctional phenolic resin is not particularly limited as long as it is a general polyfunctional phenolic resin. As the polyfunctional phenol, a novolak type phenolic resin is preferred.

[0039] The ratio (equivalent ratio) of the equivalent of the hydroxyl group of the phenolic resin (B) to the equivalent of the epoxy group of the epoxy resin (A) is preferably 0.60 or more and 1.10 or less, more preferably 0.70 or more and 0.95 or less. Within the above range, the occurrence of ion migration can be suppressed, and the glass transition temperature, heat resistance and flame retardancy of the cured product can be enhanced.

[0040] Phenolic resin (B) preferably contains a phosphorus atom-containing phenolic resin (B1). By including the phosphorus atom-containing phenolic resin (B1), the flame retardancy of the cured product can be further enhanced. The phosphorus atom-containing phenolic resin (B1) has a structure containing a phosphorus atom and functions as a flame retardant. That is, when the structure containing a phosphorus atom is exposed to fire, it decomposes into phosphoric acid, metaphosphoric acid, and polymetaphosphoric acid in that order, and the generated phosphoric acid layer can form a non-volatile protective layer to block air. Furthermore, the generated polymetaphosphoric acid can carbonize organic substances by a strong dehydrating action, and the carbonized film can block air. Therefore, the flame retardancy of the cured product can be further enhanced.

[0041] When using the phosphorus atom-containing phenolic resin (B1), examples of its type include a phosphorus atom-containing bisphenol type phenolic resin, a phosphorus atom-containing novolak type phenolic resin, and the like. The phosphorus atom-containing phenolic resin (B1) is not particularly limited, but preferably has a structure containing a phosphorus atom represented by the formula (3) in the molecule.

[0042]

[0043] In the formula (3), * represents a bond.

[0044] The phosphorus atom-containing phenol resin (B1) can be, for example, a commercially available product. Examples of commercially available products include XZ92741.00 manufactured by Olin.

[0045] The content of the phosphorus atom-containing phenol resin (B1) is preferably 2% by mass or more based on the total amount of the phenol resin (B). The content of the phenol resin (B) is preferably 20% by mass or less based on the total amount of the phenol resin (B). Within the above range, the flame retardancy of the cured product can be further enhanced.

[0046] <Inorganic filler> As described above, the resin composition contains an inorganic filler (C).

[0047] The inorganic filler (C) has at least two peaks, a first peak and a second peak, in the particle size distribution. The particle size indicated by the position of the first peak is larger than the particle size indicated by the position of the second peak. That is, in the inorganic filler (C), at least two kinds of particles, large particles and small particles, are mixed. Therefore, when the inorganic filler (C) contains two kinds of large and small particles, the increase in the viscosity of the resin composition or its semi-cured product is suppressed compared to the case where it contains one kind of particle, so that the moldability of the resin composition or its semi-cured product can be improved.

[0048] The particle size indicated by the position of the first peak of the inorganic filler (C) is preferably greater than 3 μm and 8 μm or less in the particle size distribution, more preferably 3.5 μm or more and 6.0 μm or less, and even more preferably 4 μm or more and 5 μm or less. If the particle size indicated by the position of the first peak is within the above range, the circuit filling properties of the resin composition and its semi-cured product can be improved. Furthermore, the particle size indicated by the position of the second peak of the inorganic filler (C) is preferably greater than 0.5 μm and 3 μm or less in the particle size distribution, more preferably 0.75 μm or more and 2.5 μm or less, and even more preferably 1 μm or more and 2 μm or less. If the particle size indicated by the position of the second peak is within the above range, the resin filler separation properties of the resin composition and its semi-cured product can be improved. In other words, if the particle size indicated by the position of the first peak and the particle size indicated by the position of the second peak are within the above range, the circuit filling properties and resin filler separation properties of the resin composition and its semi-cured product can be improved, resulting in good moldability.

[0049] The inorganic filler (C) includes a first inorganic filler (C1) and a second inorganic filler (C2). The first inorganic filler (C1) gives the inorganic filler (C) a first peak. That is, in the particle size distribution, the average particle size of the first inorganic filler (C1) shows the first peak. The second inorganic filler (C2) gives the inorganic filler (C) a second peak. That is, in the particle size distribution, the average particle size of the second inorganic filler (C2) shows the second peak.

[0050] Each of the first inorganic filler (C1) and the second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler. In this case, the occurrence of ion migration can be suppressed and the tracking resistance of the cured product can be improved. Furthermore, it is preferable that each of the first inorganic filler (C1) and the second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler and boehmite filler.

[0051] The combination of the first inorganic filler (C1) and the second inorganic filler (C2) is not particularly limited, but it is more preferable to select one from the group consisting of combinations of aluminum hydroxide fillers and combinations of aluminum hydroxide filler and boehmite filler. Furthermore, the combination of aluminum hydroxide filler and boehmite filler is particularly preferred for the first inorganic filler (C1) and the second inorganic filler (C2). In this case, the occurrence of unevenness, deterioration of appearance, etc. can be suppressed.

[0052] The fillers contained in the first inorganic filler (C1) and the second inorganic filler (C2) undergo thermal decomposition while releasing crystalline water when exposed to high temperatures. This thermal decomposition is an endothermic reaction. Therefore, the endothermic reaction due to the thermal decomposition and the released crystalline water suppress the rise in temperature of the cured product surface caused by the application of high voltage, thereby suppressing carbonization of the cured product. For the above reasons, it is presumed that the tracking resistance of the cured product will be improved. Also, for the same reason, it is presumed that the flame retardancy of the cured product will be improved.

[0053] The mass ratio of the first inorganic filler (C1) to the second inorganic filler (C2) is preferably 10:1 to 1:2, more preferably 10:1 to 1:1, and even more preferably 10:1 to 4:1. Within this range, moldability can be improved, and the tracking resistance and flame retardancy of the cured product can be enhanced.

[0054] The total content of the first inorganic filler (C1) and the second inorganic filler (C2) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, based on 100 parts by mass of the total epoxy resin (A) and phenolic resin (B). The total content of the first inorganic filler (C1) and the second inorganic filler (C2) is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less, based on 100 parts by mass of the total epoxy resin (A) and phenolic resin (B). Within the above range, the tracking resistance and flame retardancy of the cured product can be further improved.

[0055] The total content of the first inorganic filler (C1) and the second inorganic filler (C2) is preferably 50% by mass or more, and more preferably 80% by mass or more, relative to 100% by mass of inorganic filler (C). Alternatively, the total content of the first inorganic filler (C1) and the second inorganic filler (C2) is preferably 100% by mass or less, and more preferably 100% by mass, relative to 100% by mass of inorganic filler (C). In other words, inorganic filler (C) may contain only the first inorganic filler (C1) and the second inorganic filler (C2). Within the above range, moldability can be further improved, and the tracking resistance and flame retardancy of the cured product can be further enhanced.

[0056] The inorganic filler (C) may further include, as necessary, a third inorganic filler (C3) that is different from the first inorganic filler (C1) and the second inorganic filler (C2), without impairing the effects of the present disclosure.

[0057] The third inorganic filler (C3) preferably contains a molybdenum compound filler. Including a molybdenum compound filler can improve the drillability of the cured product. The molybdenum compound filler acts as a lubricant during drilling of the substrate, and is presumed to improve the drillability of the cured product by suppressing drill wear caused by, for example, the first inorganic filler (C1) and the second inorganic filler (C2).

[0058] The molybdenum compound filler is not particularly limited, but examples include molybdate compound fillers such as zinc molybdate filler, calcium molybdate filler, and magnesium molybdate filler, as well as carriers supporting these molybdate compound fillers. The carrier is not particularly limited, but examples include talc. Generally, the specific gravity of the molybdenum compound filler is greater than that of the first inorganic filler (C1) and second inorganic filler (C2), such as aluminum hydroxide filler, resulting in a large difference in specific gravity with the resin component. Therefore, from the viewpoint of dispersibility in the resin composition, it is preferable to use the molybdenum compound filler in the form of a carrier on which it is supported.

[0059] The average particle size of the third inorganic filler (C3) is preferably 1 μm or more and 5 μm or less, more preferably 2 μm or more and 4 μm or less.

[0060] When the inorganic filler (C) contains a third inorganic filler (C3), the content of the third inorganic filler (C3) is not particularly limited, but is preferably 2% by mass or more relative to 100% by mass of the inorganic filler (C). Also, when the inorganic filler (C) contains a third inorganic filler (C3), the content of the third inorganic filler (C3) is not particularly limited, but is preferably 20% by mass or less relative to 100% by mass of the inorganic filler (C). Within the above range, drillability can be further improved.

[0061] The inorganic filler (C) may be surface-treated with a silane coupling agent. The silane coupling agent is not particularly limited, but examples include vinyltriethoxysilane, vinyltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropylethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, glycidoxypropyltriethoxysilane, isocyanatetopropyltriethoxysilane, and the like. The silane coupling agent used may be a single type or a combination of two or more types.

[0062] <Additives> The resin composition may further contain additives as needed, to the extent that they do not impair the effects of the present disclosure. Additives are not particularly limited, but examples include curing accelerators, polymerization initiators, flame retardants, colorants, coupling agents, heat stabilizers, antioxidants, defoamers, antistatic agents, dyes, pigments, polymerization inhibitors, lubricants, and the like.

[0063] Curing accelerators act catalytically on the curing (crosslinking) reaction of resin compositions, accelerating the reaction. They can also improve the glass transition temperature and heat resistance of the cured product.

[0064] Examples of curing accelerators include imidazoles such as 2-ethyl-4-methylimidazole, 2-methylimidazole, and 2-phenyl-4-methylimidazole; amines such as dimethylbenzylamine, triethylenediamine, benzyldimethylamine, and triethanolamine; organic phosphines such as triphenylphosphine, diphenylphosphine, and phenylphosphine; tetra-substituted phosphonium or tetra-substituted borates such as tetraphenylphosphonium-ethyltriphenylborate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole-tetraphenylborate.

[0065] When a resin composition contains a curing accelerator, the amount of the curing accelerator is appropriately adjusted according to the content and type of epoxy resin (A) and phenolic resin (B). The inclusion of a curing accelerator in the resin composition accelerates the curing reaction and improves the glass transition temperature and heat resistance of the cured product.

[0066] <Preparation of Resin Composition> Methods for preparing the resin composition include, for example, mixing epoxy resin (A), phenolic resin (B), and inorganic filler (C) in predetermined proportions, but are not particularly limited. Additives may be added and mixed as needed.

[0067] Furthermore, the resin composition may contain an organic solvent. That is, it is preferable that the resin composition be used as a varnish-state resin composition containing an organic solvent. A varnish-state resin composition is one in which an organic solvent is further added to the components contained in the above-mentioned resin composition.

[0068] The above-mentioned varnished resin composition is prepared as follows. First, components of the resin composition that can be dissolved in an organic solvent are added to the organic solvent, stirred, and mixed to prepare a mixture. Alternatively, this mixture may be prepared by stirring and mixing while heating. Next, components that cannot be dissolved in the organic solvent are added to the above mixture, and the mixture is dispersed using a ball mill, bead mill, planetary mixer, etc., until the desired dispersion state is reached, thereby preparing a varnished resin composition. The organic solvent used here is not particularly limited, but it is preferable that it can dissolve epoxy resin (A), phenolic resin (B), etc., and does not inhibit the curing reaction of the resin composition. Specifically, examples of organic solvents include toluene and methyl ethyl ketone (MEK).

[0069] (1.2) Physical Properties <Resin Filler Separability> The resin composition and its semi-cured product have good resin filler separation properties. Note that resin filler separation properties are physical properties related to moldability. If the resin filler separation properties are not good, when filling the resin composition or its semi-cured product, the resin components and fillers do not flow together, and only the resin components flow too far, resulting in poor dispersibility of the filler in the resin composition. In other words, the epoxy resin (A) and phenolic resin (B), which are the resin components, separate from the inorganic filler (C), and the desired physical properties of the cured product do not appear, impairing the reliability of substrates such as metal-clad laminates and wiring boards.

[0070] <Circuit Filling Properties> The resin composition and its semi-cured product have good circuit filling properties. Note that circuit filling properties are a physical property related to moldability. If the circuit filling properties are not good, the resin composition or its semi-cured product will not be sufficiently filled between the wires, and voids will occur in the insulating layer between the wires when the product is cured.

[0071] <Tracking Resistance> The cured product of the resin composition has good tracking resistance. That is, the cured product suppresses the occurrence of tracking and the occurrence of dielectric breakdown. The tracking performance of the cured product is indicated by the Comparative Tracking Index (CTI), and the CTI of the cured product is preferably 600V or higher.

[0072] <Glass Transition Temperature> The cured product of the resin composition has a good glass transition temperature. The glass transition temperature of the cured product is preferably 190°C or higher.

[0073] <Oven Heat Resistance> The cured resin composition has good oven heat resistance. If the oven heat resistance is not good, metal-clad laminates, wiring boards, etc. will blister when exposed to high temperatures. Blistering is a form of delamination in metal-clad laminates, wiring boards, etc., and is a delamination caused by partial bulging that occurs between insulating layers or between the insulating layer and the copper foil in the test piece. The oven heat resistance of the cured product is preferably 270°C or higher.

[0074] (2) Prepreg Figure 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to the embodiment.

[0075] The prepreg 1 comprises a resin composition or a semi-cured resin composition and a fibrous substrate 12. The fibrous substrate 12 is impregnated with the resin composition. The prepreg 1 may also include a resin layer 11. If the prepreg 1 includes a resin layer 11, the resin layer 11 contains the resin composition or a semi-cured resin composition. Also, as shown in Figure 1, the prepreg 1 has one fibrous substrate 12, but it may have two or more fibrous substrates 12.

[0076] The fibrous base material 12 is a reinforcing material, and its material is not particularly limited. The thickness of the fibrous base material 12 is not particularly limited, but is preferably 10 μm or more, more preferably 30 μm or more. The thickness of the fibrous base material 12 is preferably 300 μm or less, more preferably 200 μm or less.

[0077] Specific examples of the fibrous base material 12 include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. Preferred types of glass cloth are #7628, #1501, #2116, #1080, #1078, and #106.

[0078] In manufacturing prepreg 1, it is preferable that the glass cloth be treated with a coupling agent before impregnation with the resin composition of stage A. Treating the glass cloth with a coupling agent in this way improves the adhesion between the glass cloth and the resin composition. The coupling agent is not particularly limited, but examples include those that can be used for surface treatment of the inorganic filler (C) mentioned above.

[0079] The manufacturing method for the prepreg 1 involves impregnating the fibrous substrate 12 with varnish by immersing it in varnish or by applying varnish to the fibrous substrate 12. This impregnation can be repeated multiple times as needed. Furthermore, by repeatedly impregnating with multiple varnishes having different compositions and concentrations, a resin layer 11 containing a resin composition or a semi-cured product thereof with a desired composition and impregnation amount can be obtained.

[0080] Furthermore, regarding the method for producing the prepreg 1, for example, the organic solvent may be reduced or removed from the resin layer 11 by heating the resin layer 11, which is produced by impregnating a fibrous substrate 12 with a varnish containing a resin composition and an organic solvent. When reducing or removing the organic solvent from the resin layer 11 by heating the resin layer 11, for example, the temperature is 80°C or higher and 180°C or lower, and the time is 1 minute or higher and 10 minutes or lower.

[0081] The method for producing the prepreg 1 comprising the above-described resin composition or a semi-cured product of the resin composition and the fibrous base material 12 is not limited to the method described above. In other words, the prepreg 1 according to this embodiment, produced using the above-described resin composition, can be produced by any appropriate method.

[0082] Since the prepreg 1 according to this embodiment is manufactured using the above-mentioned resin composition, it is possible to achieve both good moldability and tracking resistance.

[0083] (3) Resin-coated film Figure 2 is a schematic cross-sectional view showing an example of a resin-coated film 2 according to the embodiment.

[0084] The resin-coated film 2 is used for multilayering (build-up method) of the wiring board 5. The resin-coated film 2 is a film overall. The resin-coated film 2 comprises a resin layer 21 and a support film 22.

[0085] The resin layer 21 includes a resin composition or a semi-cured product of the resin composition. The resin composition and its semi-cured product become cured products when heated. In this way, the resin layer 21 can form an insulating layer.

[0086] The thickness of the resin layer 21 is not particularly limited, but is preferably 120 μm or less, more preferably 100 μm or less, even more preferably 60 μm or less, and even more preferably 40 μm or less. This makes it possible to reduce the thickness of the insulating layer and realize the thinning of substrates such as metal-clad laminates and wiring boards. The thickness of the resin layer 21 is preferably 10 μm or more.

[0087] The support film 22 supports the resin layer 21. This support film 22 provides with the resin layer 21, making it easier to handle.

[0088] The support film 22 is, for example, an electrically insulating film. The support film 22 is not particularly limited, but examples include polyethylene terephthalate (PET) film, polyimide film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, aramid film, polycarbonate film, and polyarylate film.

[0089] A release agent layer (not shown) may be provided on the surface of the support film 22 that supports the resin layer 21. The release agent layer allows the support film 22 to be peeled off from the resin layer 21 as needed. Preferably, after the resin layer 21 is cured to form an insulating layer, the support film 22 is peeled off from this insulating layer.

[0090] In Figure 2, one side of the resin layer 21 is covered by the support film 22, but the other side of the resin layer 21 may be covered with a protective film (not shown). By covering both sides of the resin layer 21 with the support film 22 and the protective film, the resin layer 21 becomes easier to handle. In addition, it is possible to suppress the adhesion of foreign matter to the resin layer 21.

[0091] The protective film is, for example, an electrically insulating film. While not particularly limited, examples of protective films include polyethylene terephthalate (PET) film, polyolefin film, polyester film, and polymethylpentene film.

[0092] A release agent layer may be provided on the surface of the protective film that is superimposed on the resin layer 21. The release agent layer allows the protective film to be peeled off from the resin layer 21 as needed.

[0093] Since the resin-coated film 2 according to this embodiment is manufactured using the above-mentioned resin composition, it is possible to achieve both good moldability and tracking resistance.

[0094] (4) Resin-coated metal foil Figure 3 is a schematic cross-sectional view showing an example of resin-coated metal foil 3 according to the embodiment.

[0095] The resin-coated metal foil 3 is in the form of a film overall. The resin-coated metal foil 3 comprises a resin layer 31 and a metal foil 32. The resin-coated metal foil 3 is used for multilayering (build-up method) of wiring boards 5, etc.

[0096] The resin layer 31 includes a resin composition or a semi-cured product of the resin composition. The resin composition and its semi-cured product can be cured by heating. In this way, the resin layer 31 can form an insulating layer.

[0097] The thickness of the resin layer 31 is not particularly limited, but is preferably 120 μm or less, more preferably 100 μm or less, even more preferably 60 μm or less, and even more preferably 40 μm or less. This makes it possible to reduce the thickness of the insulating layer formed when the resin layer 31 hardens, thereby enabling the thinning of metal-clad laminates, wiring boards, etc. The thickness of the resin layer 31 is preferably 10 μm or more.

[0098] The metal foil 32 is in close contact with the resin layer 31. Copper foil is a specific example of the metal foil 32, but it is not limited to this. The metal foil 32 can form wiring 53 by removing unwanted portions by etching using a subtractive method or the like.

[0099] The thickness of the metal foil 32 is not particularly limited, but is preferably 35 μm or less, and more preferably 18 μm or less. It is preferable that the thickness of the metal foil 32 is 5 μm or more.

[0100] Incidentally, the metal foil 32 may be composed of an ultrathin metal foil (for example, an ultrathin copper foil) of a so-called carrier-attached ultrathin metal foil (not shown). The carrier-attached ultrathin metal foil has a three-layer structure. That is, the carrier-attached ultrathin metal foil comprises a carrier, a release layer provided on the surface of the carrier, and an ultrathin metal foil provided on the surface of the release layer. The ultrathin metal foil is so thin that it is difficult to handle on its own, and of course it is thinner than the carrier. The carrier is a metal foil (for example, a copper foil) that serves to protect and support the ultrathin metal foil. The carrier-attached ultrathin metal foil has a certain thickness, making it easy to handle. The thickness of the ultrathin metal foil and the carrier are not particularly limited, but for example, the thickness of the ultrathin metal foil is 1 μm or more and 10 μm or less, and the thickness of the carrier is 18 μm or more and 35 μm or less. The ultrathin metal foil can be peeled off from the release layer as needed.

[0101] When using a carrier-attached ultrathin metal foil, the resin-coated metal foil 3 can be manufactured as follows: A resin composition is applied to the surface of the carrier-attached ultrathin metal foil and heated to form a resin layer 31. Then, the carrier is peeled off from the ultrathin metal foil. The ultrathin metal foil is then adhered to the surface of the resin layer 31 as a metal foil 32. Preferably, the release layer is peeled off together with the carrier and does not remain on the surface of the ultrathin metal foil, but even if it remains, it can be easily removed. The ultrathin metal foil adhered to the surface of the resin layer 31 can be used as a seed layer in the Modified Semi-Additive Process (MSAP), and electroplating can be performed on this seed layer to form wiring 53.

[0102] Since the resin-coated metal foil 3 according to this embodiment is manufactured using the above-mentioned resin composition, it is possible to achieve both good moldability and tracking resistance.

[0103] (5) Metal-clad laminate Figure 4 is a schematic cross-sectional view showing an example of a metal-clad laminate 4 according to the embodiment.

[0104] The metal-clad laminate 4 comprises an insulating layer 41 and a metal layer 43. The insulating layer 41 may contain a cured resin composition, or at least one cured prepreg 1. When the insulating layer 41 is manufactured using the prepreg 1, the insulating layer 41 contains a fibrous substrate 42. The fibrous substrate 42 is the same as the fibrous substrate 12 described above. Thus, the metal-clad laminate 4 can be manufactured using the prepreg 1 as the material. The insulating layer 41 is electrically insulating and is an insoluble and infusible layer. The metal layer 43 is in close contact with the insulating layer 41.

[0105] The metal layer 43 is not particularly limited as long as it is a layer containing metal. A specific example of the metal layer 43 is copper foil. The thickness of the metal layer 43 is preferably 18 μm or more and 210 μm or less. The ten-point average roughness Rzjis of the metal layer 43 is preferably 5.0 μm or more. In this case, the adhesion between the insulating layer 41 and the metal layer 43 is further improved.

[0106] The manufacturing method for the metal-clad laminate 4 includes, for example, a step of overlapping a metal layer 43, such as a metal foil, on one or both sides of a laminate consisting of one prepreg 1 or two or more prepreg 1, and then heating and pressurizing it. Preferably, before overlapping the metal layer 43 on the laminate, the surface of the metal layer 43 (at least the side overlapping the laminate) is treated with a coupling agent. When the metal layer 43 is surface-treated with a coupling agent in this way, the coupling agent bonds the organic material in the prepreg 1 with the metal layer 43, thereby further improving the adhesion between the insulating layer 41 and the metal layer 43. The coupling agent can be any of the above-mentioned ones. The heating and pressurizing conditions are not particularly limited. Figure 4 shows a metal-clad laminate 4 obtained by the step of overlapping a metal layer 43 on both sides of a laminate consisting of one prepreg 1 and then heating and pressurizing it.

[0107] The hydrolyzable chlorine contained in the metal-clad laminate 4 is preferably 20 ppm or less. In this case, the chloride ions generated in the presence of water can be reduced, and thus the occurrence of ion migration can be further suppressed. The method for measuring the concentration of hydrolyzable chlorine is not particularly limited, but examples include ion chromatography.

[0108] Since the metal-clad laminate 4 according to this embodiment is manufactured using the above-mentioned resin composition, good tracking resistance can be achieved.

[0109] (6) Wiring board Figure 5 is a schematic cross-sectional view showing an example of a wiring board 5 according to the embodiment.

[0110] The wiring board 5 comprises an insulating layer 51 and wiring 53. The insulating layer 51 may contain a cured resin composition, or at least one cured prepreg 1. When the insulating layer 51 is manufactured using the prepreg 1, the insulating layer 51 contains a fibrous base material 52. The fibrous base material 52 is the same as the fibrous base material 12 described above. Thus, the wiring board 5 can be manufactured using the prepreg 1 as the material. The insulating layer 51 is an electrically insulating layer that is insoluble and infusible.

[0111] The wiring board 5 includes a conductor layer 530. The conductor layer 530 is in close contact with the insulating layer 51. In this disclosure, "conductor layer" means a conductive layer such as a signal layer, a power layer, and a ground layer. The conductor layer 530 includes wiring 53.

[0112] The concept of a wiring board 5 includes wiring boards having two or fewer conductor layers 530 and multilayer wiring boards having three or more conductor layers 530. Figure 5 shows a wiring board having two conductor layers 530 and one insulating layer 51.

[0113] The wiring board 5 can be manufactured, for example, by using a subtractive method with a metal-clad laminate 4 as the material. Furthermore, the wiring board 5 may be multilayered using a build-up method with a resin-coated film 2 and a resin-coated metal foil 3.

[0114] The wiring board 5 may have one or more through-hole platings 54. The through-hole platings 54 are formed, for example, by drilling holes in the insulating layer 51, performing a desmear treatment, and then applying copper plating or the like to the inner walls of these holes. The desmear treatment can be performed, for example, by the permanganate method. Although not shown in the figures, the wiring board 5 may also have one or more blind via holes. The holes may be through holes or non-through holes.

[0115] Here, since the insulating layer 51 is manufactured using a resin composition, it contains a first inorganic filler (C1) and a second inorganic filler (C2). By including these fillers, the occurrence of ion migration can be suppressed and the tracking resistance of the cured product can be improved. Specifically, CAF is less likely to occur along the fibrous substrate 52 inside the insulating layer 51 (for example, in the X portion of Figure 5). As a result, the long-term insulation reliability of the wiring board 5 is improved.

[0116] The hydrolyzable chlorine contained in the wiring board 5 is preferably 20 ppm or less. In this case, the chloride ions generated in the presence of water can be reduced, and thus the occurrence of ion migration can be further suppressed. The method for measuring the concentration of hydrolyzable chlorine is not particularly limited, but examples include ion chromatography.

[0117] As described above, according to the embodiment, the occurrence of ion migration can be suppressed and tracking resistance can be improved. In other words, since the wiring board 5 according to the embodiment is manufactured using the above resin composition, good tracking resistance can be achieved.

[0118] 3. Aspects As will be clear from the above embodiments, this disclosure includes the following aspects. Hereafter, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0119] A resin composition according to a first aspect of this disclosure contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C). The epoxy resin (A) includes a dicyclopentadiene type epoxy resin (A1) and a trisphenolmethane type epoxy resin (A2). The inorganic filler (C) has at least a first peak and a second peak showing a particle size smaller than the first peak in a volume-based particle size distribution measurement measured by laser diffraction-scattering. The inorganic filler (C) includes a first inorganic filler (C1) that gives the first peak and a second inorganic filler (C2) that gives the second peak. The first inorganic filler (C1) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler. The second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler.

[0120] In the first embodiment, the resin composition according to the second aspect of this disclosure has a particle size greater than 3 μm and less than or equal to 8 μm, where the position of the first peak indicates the particle size.

[0121] In the third aspect of the present disclosure, the resin composition, in the first or second aspect, has a particle size of 0.5 μm or more and 3 μm or less, indicated by the position of the second peak.

[0122] In the fourth aspect of the present disclosure, the resin composition is such that, in any one of the first to third aspects, the mass ratio of the first inorganic filler (C1) to the second inorganic filler (C2) is 10:1 to 1:2.

[0123] In the fifth aspect of the present disclosure, the resin composition is such that, in any one of the first to fourth aspects, the total content of the first inorganic filler (C1) and the second inorganic filler (C2) is 50 parts by mass or more and 150 parts by mass or less, based on 100 parts by mass of the total of the epoxy resin (A) and the phenolic resin (B).

[0124] In the sixth aspect of the present disclosure, the resin composition is such that, in any one of the first to fifth aspects, the content of the dicyclopentadiene type epoxy resin (A1) is 10% by mass or more and 50% by mass or less, relative to the total amount of epoxy resin (A) and phenol resin (B).

[0125] The resin composition according to the seventh aspect of this disclosure, in any one of the first to sixth aspects, has a mass ratio of dicyclopentadiene-type epoxy resin (A1) to trisphenolmethane-type epoxy resin (A2) of 1:5 to 5:1.

[0126] In the eighth aspect of this disclosure, the resin composition comprises, in any one of the first to seventh aspects, a phenolic resin (B) containing a phosphorus atom-containing phenolic resin (B1).

[0127] A prepreg (1) according to the ninth aspect of the present disclosure comprises a resin composition or a semi-cured product thereof according to any one of the first to eighth aspects, and a fibrous substrate (12).

[0128] A resin-coated film (2) according to the tenth aspect of the present disclosure comprises a resin layer (21) containing a resin composition or a semi-cured product thereof according to any one of the first to eighth aspects, and a support film (22).

[0129] A resin-coated metal foil (3) according to the eleventh aspect of the present disclosure comprises a resin layer (31) containing a resin composition or a semi-cured product thereof according to any one of the first to eighth aspects, and a metal foil (32).

[0130] A metal-clad laminate (4) according to a twelfth aspect of the present disclosure comprises an insulating layer (41) containing a cured product of a resin composition according to any one of the first to eighth aspects, and a metal layer (43).

[0131] A metal-clad laminate (4) according to a thirteenth aspect of the present disclosure comprises an insulating layer (41) containing a cured product of the prepreg (1) according to a ninth aspect, and a metal layer (43).

[0132] A wiring board (5) according to a fourteenth aspect of the present disclosure comprises an insulating layer (51) containing a cured product of a resin composition according to any one of the first to eighth aspects, and wiring (53).

[0133] A wiring board (5) according to a 15th aspect of the present disclosure comprises an insulating layer (51) containing a cured prepreg (1) according to a 9th aspect, and wiring (53).

[0134] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0135] (1) Preparation of Resin Compositions The components shown in Table 1 were used as raw materials for the resin compositions. The epoxy resin (A), phenolic resin (B), inorganic filler (C), and additives were blended in the amounts shown in Table 1, dissolved or dispersed in a solvent (methyl ethyl ketone), and then stirred and mixed in a disperser to homogenize them, thereby preparing the varnish-state resin compositions of the Examples and Comparative Examples, each with a solid content concentration of 70% by mass. Details of each component used are as follows.

[0136] <Epoxy Resin (A)> - Epoxy Resin #1: Manufactured by DIC Corporation, product name "HP-7200H", dicyclopentadiene type, epoxy equivalent: 278 g / eq. - Epoxy Resin #2: Manufactured by DIC Corporation, product name "HP-7241", trisphenolmethane type, epoxy equivalent: 168 g / eq.

[0137] <Phenolic Resin (B)> - Phenolic Resin #1: Manufactured by DIC Corporation, product name "TD-2090", phenol novolac type, hydroxyl group equivalent: 105 g / eq. - Phenolic Resin #2: Manufactured by Olin, product name "XZ92741.00", phosphorus atom-containing phenolic resin, phosphorus atom content: 9.6% by mass, hydroxyl group equivalent: 550 g / eq.

[0138] <Inorganic Fillers (C)> - Inorganic Filler #1: Manufactured by Kawai Lime Industry Co., Ltd., Product Name "ALH-F", Aluminum Hydroxide Filler, Average Particle Size (D50): 4.8 μm - Inorganic Filler #2: Manufactured by Kawai Lime Industry Co., Ltd., Product Name "ALH-1F", Aluminum Hydroxide Filler, Average Particle Size (D50): 2.2 μm - Inorganic Filler #3: Manufactured by Kawai Lime Industry Co., Ltd., Product Name "Cerasure BMB-2", Boehmite Filler, Average Particle Size (D50): 1.5 μm - Inorganic Filler #4: Manufactured by Kamishima Chemical Industry Co., Ltd., Product Name "Magsees EP1-S", Magnesium Hydroxide Filler, Average Particle Size (D50): 2.0 μm - Inorganic filler #5: Manufactured by Admatex Co., Ltd., product name "SC2500-SXJ", aminosilane-treated silica filler, average particle size (D50): 0.9 μm - Inorganic filler #6: Manufactured by Sherwin-Williams Ltd., product name "Kemgard911C", zinc molybdate-supported talc filler, average particle size (D50): 3.3 μm.

[0139] <Additives> - Curing accelerator: Manufactured by Shikoku Chemicals Co., Ltd., product name "2E4MZ", compound name "2-ethyl-4-methylimidazole".

[0140] (2) Preparation of evaluation substrates <Preparation of prepregs> Glass cloth (manufactured by Nanya Co., Ltd., product name "#7628") was prepared as a fibrous substrate. These glass cloths consist of a woven fabric in which the warp and weft threads are woven approximately perpendicular to each other. The glass cloth was impregnated with each resin composition in varnish state prepared in "(1) Preparation of resin composition" so that the thickness of the cured prepreg was 200 μm. The resin composition impregnated into the glass cloth was heated and dried at 160°C using a non-contact heating unit until it became a semi-cured product. This removed the solvent from the resin composition and yielded prepregs of the example and comparative example, comprising glass cloth and a semi-cured product of the resin composition impregnated into the glass cloth. The resin layer content in the prepreg was 46% by mass, with the total prepreg being 100% by mass.

[0141] <Preparation of Metal-Clad Laminates> Four prepregs were stacked to obtain a laminate, and copper foil (manufactured by Nanya Co., Ltd., product number "NPHE", thickness: 35 μm) was placed on both sides of the obtained laminate to obtain a copper-foil-clad laminate. This copper-foil-clad laminate was heated and pressurized at 220°C, 3 MPa for 90 minutes to obtain a metal-clad laminate with a thickness of 0.8 mm.

[0142] (3) Evaluation <Resin filler separation properties and circuit filling properties> A wiring board was obtained by etching a grid pattern of conductive wiring onto the metal foil on both sides of the fabricated metal-clad laminate so that the residual copper ratio was 60% on each side. The fabricated prepreg was laminated so that it was in close contact with each of the conductive wirings on both sides of this wiring board. Then, a laminate was obtained by heating and pressurizing at 220°C and 3 MPa for 90 minutes. This laminate was cut in the thickness direction between the conductive wirings.

[0143] For resin filler separation, the presence or absence of separation between the resin component and the inorganic filler in the cured material at the cut surface was observed visually. The observation results were classified according to the following evaluation criteria, and the resin filler separation was evaluated.

[0144] A: In a cured product of a resin composition derived from the resin layer of resin-coated metal foil filled between conductor wiring, separation of the resin component and the inorganic filler was not observed. B: In a cured product of a resin composition derived from the resin layer of resin-coated metal foil filled between conductor wiring, separation of the resin component and the inorganic filler was observed.

[0145] For circuit filling performance, the presence or absence of voids in the cut surface was observed visually. The observation results were classified according to the following evaluation criteria, and circuit filling performance was evaluated.

[0146] A: The resin composition derived from the resin layer of the resin-coated metal foil penetrates sufficiently between the conductor wiring, and no voids are observed. B: The resin composition derived from the resin layer of the resin-coated metal foil penetrates insufficiently between the conductor wiring, and voids are observed.

[0147] <Tracking Resistance> The copper foil adhering to both sides of the fabricated metal-clad laminate was removed by etching to obtain an unclad plate, which was used as the test specimen. A tracking resistance test was performed on this test specimen in accordance with IEC 60112. The comparative tracking index was used as the indicator and evaluated according to the evaluation criteria below.

[0148] A: 600V or higher. B: Less than 600V.

[0149] <Glass Transition Temperature> The copper foil adhering to both sides of the fabricated metal-clad laminate was removed by etching to obtain an unclad plate. This unclad plate was cut at a 45° angle (bias direction) to the warp or weft threads of the glass cloth to obtain a test specimen measuring 5 mm × 55 mm × 0.8 mmt. Using a dynamic viscoelasticity measuring device (SII Nanotechnology Co., Ltd., part number "DMS6100"), the tanδ was measured when the temperature was increased from 30°C to 350°C under a heating condition of 5°C / min (DMA method), and the peak temperature was defined as the glass transition temperature.

[0150] <Oven Heat Resistance> The prepared metal-clad laminate was cut into 50mm x 50mm pieces to make test specimens. These test specimens were placed in ovens at 270, 280, 290, and 300°C for one hour each, and the presence or absence of blistering was visually checked. The maximum temperature at which no blistering occurred in the metal-clad laminate was defined as the oven heat resistance temperature.

[0151]

[0152] 1. Prepreg 2. Resin-coated film 3. Resin-coated metal foil 4. Metal-clad laminate 5. Wiring board

Claims

1. The material contains an epoxy resin (A), a phenolic resin (B), and an inorganic filler (C), wherein the epoxy resin (A) comprises a dicyclopentadiene type epoxy resin (A1) and a trisphenolmethane type epoxy resin (A2), the inorganic filler (C) has at least a first peak and a second peak showing a particle size smaller than the first peak in volume-based particle size distribution measurement measured by laser diffraction-scattering, the inorganic filler (C) comprises a first inorganic filler (C1) that gives the first peak and a second inorganic filler (C2) that gives the second peak, the first inorganic filler (C1) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler. The resin composition wherein the second inorganic filler (C2) is at least one filler selected from the group consisting of aluminum hydroxide filler, boehmite filler, magnesium hydroxide filler, dawsonite filler, calcium aluminate hydrate filler, calcium borate filler, and zinc borate filler.

2. The resin composition according to claim 1, wherein the particle size indicated by the position of the first peak is greater than 3 μm and 8 μm or less.

3. The resin composition according to claim 1, wherein the particle size indicated by the position of the second peak is 0.5 μm or more and 3 μm or less.

4. The resin composition according to claim 1, wherein the mass ratio of the first inorganic filler (C1) to the second inorganic filler (C2) is 10:1 to 1:

2.

5. The resin composition according to claim 1, wherein the total content of the first inorganic filler (C1) and the second inorganic filler (C2) is 50 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the total of the epoxy resin (A) and the phenolic resin (B).

6. The resin composition according to claim 1, wherein the content of the dicyclopentadiene type epoxy resin (A1) is 10% by mass or more and 50% by mass or less, relative to the total amount of the epoxy resin (A) and the phenolic resin (B).

7. The resin composition according to claim 1, wherein the mass ratio of the dicyclopentadiene-type epoxy resin (A1) to the trisphenolmethane-type epoxy resin (A2) is 1:5 to 5:

1.

8. The resin composition according to claim 1, wherein the phenolic resin (B) comprises a phosphorus atom-containing phenolic resin (B1).

9. A prepreg comprising a resin composition according to any one of claims 1 to 8 or a semi-cured product of the resin composition, and a fibrous substrate.

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

11. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 8 or a semi-cured product of the resin composition, and a metal foil.

12. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 8, and a metal layer.

13. A metal-clad laminate comprising an insulating layer containing a cured prepreg according to claim 9, and a metal layer.

14. A wiring board comprising an insulating layer containing a cured product of a resin composition according to any one of claims 1 to 8, and wiring.

15. A wiring board comprising an insulating layer containing a cured prepreg according to claim 9, and wiring.

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