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

Abstract

The present disclosure addresses the problem of providing a resin composition capable of giving cured objects having a reduced coefficient of linear expansion, high adhesion, and excellent flame retardancy. The resin composition comprises a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and phosphorus-containing compounds (D). The phosphorus-containing compounds (D) include a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2). The mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is 0.5-5.0.

Description

Resin compositions, prepregs, resin-coated films, resin-coated metal foils, metal-clad laminates, and wiring boards

[0001] This disclosure generally relates to resin compositions, prepregs, resin-coated films, resin-coated metal foils, metal-clad laminates, and wiring boards, and more particularly to resin compositions containing maleimide compounds, and to prepregs, resin-coated films, resin-coated metal foils, metal-clad laminates, and wiring boards using this resin composition.

[0002] Patent Document 1 discloses a resin composition containing a maleimide compound (A) having an alkyl group having 6 or more carbon atoms and / or an alkylene group having 6 or more carbon atoms, a phosphine oxide compound (B) having a specific structure, and an epoxy compound (C).

[0003] However, the resin composition described in Patent Document 1 had the problem of being difficult to achieve a low coefficient of thermal expansion, high adhesion, and excellent flame retardancy in the cured product.

[0004] International Publication No. 2021 / 261306

[0005] The object of this disclosure is to provide resin compositions, prepregs, resin-coated films, resin-coated metal foils, metal-clad laminates, and wiring boards that can achieve a low coefficient of thermal expansion, high adhesion, and excellent flame retardancy in cured products.

[0006] A resin composition according to one aspect of the present disclosure contains a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D). The phosphorus-containing compound (D) comprises a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2). The mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is 0.5 or more and 5.0 or less.

[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 a 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 foil.

[0011] 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.

[0012] A metal-clad laminate according to one aspect of the present disclosure comprises an insulating layer containing a cured prepreg and a metal foil.

[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 cross-sectional view showing a prepreg according to the embodiment. Figure 2 is a cross-sectional view showing a resin-coated film according to the embodiment. Figure 3 is a cross-sectional view showing a resin-coated metal foil according to the embodiment. Figure 4 is a cross-sectional view showing a metal-clad laminate according to the embodiment. Figure 5 is a cross-sectional view showing a wiring board according to the embodiment.

[0015] 1. Overview The resin composition (M) according to the embodiments of this disclosure contains a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D). The phosphorus-containing compound (D) includes a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2). The mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is 0.5 or more and 5.0 or less.

[0016] The resin composition (M) contains resin components such as a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D), thereby achieving both a low coefficient of thermal expansion and high adhesion of the cured product. Furthermore, the phosphorus-containing compound (D) includes a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2), and the mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is between 0.5 and 5.0, thereby achieving a low coefficient of thermal expansion, high adhesion, and excellent flame retardancy of the cured product.

[0017] 2. Details 2.1 Composition of the resin composition The resin composition (M) according to the embodiment contains a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D).

[0018] <Maleimide Compound> The resin composition (M) contains a maleimide compound (A). The maleimide compound (A) can enhance the heat resistance and dielectric properties of the cured product of the resin composition (M).

[0019] The number of maleimide groups in maleimide compound (A) is not particularly limited, but it is preferable that maleimide compound (A) has two or more maleimide groups in one molecule. In other words, it is preferable that maleimide compound (A) is a polyfunctional maleimide compound. In this case, maleimide compound (A) has high reactivity, and the cured product of resin composition (M) may have a rigid chemical structure. This can lower the coefficient of linear expansion of the cured product of resin composition (M) and further increase its heat resistance. Furthermore, it is more preferable that the maleimide groups in maleimide compound (A) are N-phenylmaleimide groups.

[0020] Furthermore, maleimide compound (A) does not contain a phosphorus atom in its molecule. In other words, maleimide compound (A) does not contain phosphorus-containing maleimide compounds.

[0021] The proportion of maleimide compound (A) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total amount of resin components. The proportion of maleimide compound (A) is preferably 75% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 50% by mass or less, based on the total amount of resin components. Within the above range, the glass transition temperature of the cured product of the resin composition (M) can be increased and the coefficient of linear expansion can be decreased. In this disclosure, "resin components" refers to the total of maleimide compound (A), benzoxazine compound (B), epoxy compound (C), phosphorus-containing compound (D), and elastomer (E).

[0022] As the maleimide compound (A), for example, a commercially available product can be used. Examples of such commercially available products include BMI-1000, BMI-2300, BMI-3000, BMI-4000, BMI-5100, BMI-7000, and BMI-HMH manufactured by Yamato Chemical Industries, Ltd.; MRI-3000-70MT and MRI-5000-60T manufactured by Nippon Kayaku Co., Ltd.; and BMI-689, BMI-5000, BMI-1500, BMI-1700, and BMI-3000 manufactured by Designer Molecules Inc. The maleimide compound (A) may be contained in the resin composition (M) as only one type, or as two or more types.

[0023] <Benzoxazine Compound> The resin composition (M) contains a benzoxazine compound (B). The benzoxazine compound (B) can lower the coefficient of thermal expansion of the cured product of the resin composition (M) and improve adhesion to metals, glass, etc.

[0024] The benzoxazine compound (B) is not particularly limited, but examples include monofunctional benzoxazine compounds, polyfunctional benzoxazine compounds, and benzoxazine compounds having reactive groups including carbon-carbon unsaturated double bonds. Preferably, the benzoxazine compound (B) is a polyfunctional benzoxazine compound having 2 to 4 benzoxazine rings. In this case, the glass transition temperature, heat resistance, and toughness of the cured resin composition (M) can be further improved.

[0025] Among the above, the benzoxazine compound (B) is preferably a benzoxazine compound having a reactive group including a carbon-carbon unsaturated double bond, and more preferably a benzoxazine compound having a reactive group that includes a carbon-carbon unsaturated double bond (hereinafter also referred to as a carbon-carbon unsaturated double bond group). In other words, it is more preferable that the benzoxazine compound (B) has a carbon-carbon unsaturated double bond group. In this case, the coefficient of linear expansion of the cured resin composition (M) can be lowered, and the adhesion to metals and glass can be further improved. Examples of carbon-carbon unsaturated double bond groups that the benzoxazine compound (B) may have include an allyl group, a vinyl group, a 1-propenyl group, etc. Among these, it is more preferable that the carbon-carbon unsaturated double bond group that the benzoxazine compound (B) may have is an allyl group. Furthermore, when the benzoxazine compound (B) has an allyl group, the bond position of the allyl group is not particularly limited and may be bonded to the benzoxazine ring or to a structure other than the benzoxazine ring.

[0026] Examples of benzoxazine compounds having reactive groups including carbon-carbon unsaturated double bonds include benzoxazine compounds having a benzoxazine group represented by formula (12) in the molecule, benzoxazine compounds having a benzoxazine group represented by formula (13) in the molecule, and benzoxazine compounds having a benzoxazine group represented by formula (12) and a benzoxazine group represented by formula (13) in the molecule.

[0027]

[0028] In formula (12), R ４３ This indicates a reactive group containing a carbon-carbon unsaturated double bond, and p is R ４３ The average value of the degree of substitution is between 1 and 4, and preferably 1.

[0029]

[0030] In formula (13), R ４４ This exhibits a reactive group containing a carbon-carbon unsaturated double bond, etc.

[0031] Examples of the benzoxazine compound having a benzoxazine group represented by formula (12) in the molecule include a benzoxazine compound represented by formula (14).

[0032]

[0033] In formula (14), R ４５ and R ４６ each independently represent a reactive group containing a carbon-carbon unsaturated double bond or the like, X represents an alkylene group, and q and r each independently represent 1 to 4.

[0034] The alkylene group is not particularly limited, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, an icosylene group, and a hexatriacontylene group. Among these, a methylene group is preferable as the alkylene group.

[0035] In formula (14), q and r are respectively the average value of the degree of substitution of R ４５ , R ４６ and are 1 to 4, preferably 1.

[0036] Examples of the benzoxazine compound having a benzoxazine group represented by formula (13) in the molecule include a benzoxazine compound represented by formula (15).

[0037]

[0038] In formula (15), R ４７ and R ４８ each independently represent a reactive group containing a carbon-carbon unsaturated double bond or the like, X represents a single bond, an oxygen atom, a carbonyl group, a methylene group, an isopropylidene group (-C(CH ３ ) ２ -), a hexafluoroisopropylidene group (-C(CF ３ ) ２ -), a phenylene group, a naphthylene group, or a tricyclodecylene group, preferably a tricyclodecylene group. The tricyclodecylene group in the present disclosure is a divalent hydrocarbon group derived from dicyclopentadiene.

[0039] Furthermore, the benzoxazine compound (B) does not have a phosphorus atom in the molecule. That is, the benzoxazine compound (B) does not include any phosphorus-containing benzoxazine compound.

[0040] For the benzoxazine compound (B), for example, a commercially available product can be used. Examples of such commercially available products include ALP-d type benzoxazine, P-d type benzoxazine, and F-a type benzoxazine manufactured by Shikoku Kasei Kogyo Co., Ltd.; KZH-5031, KZH-5032, KZH-5075, KZH-5085, and KZH-5086 manufactured by Kolon Industries, Inc.; and JBZ-BA100N, JBZ-FA100N, JBZ-DP100N, JBZ-OP100N, JBZ-OP100D, and JBZ-OP100I manufactured by JFE Chemical Corporation.

[0041] The mass ratio of the benzoxazine compound (B) to the maleimide compound (A) (mass of benzoxazine compound (B) / mass of maleimide compound (A), hereinafter also referred to as "mass ratio (R1)") is preferably 0.2 or more, more preferably 0.25 or more, and still more preferably 0.3 or more. In this case, the adhesion of the cured product of the resin composition (M) to metals, glass, and the like can be improved. The mass ratio (R1) is preferably 1.2 or less, more preferably 1.0 or less, and still more preferably 0.8 or less. In this case, the glass transition temperature of the cured product of the resin composition (M) can be increased, and the coefficient of linear expansion can be reduced.

[0042] <Epoxy Compound> The resin composition (M) contains an epoxy compound (C). The epoxy compound (C) is a compound having one or more epoxy groups in one molecule. The epoxy compound (C) can improve the adhesion of the cured product of the resin composition (M) to metals, glass, and the like, as well as heat resistance and other properties.

[0043] The epoxy compound (C) is not particularly limited, but examples include naphthalene-type epoxy compounds, cresol-type epoxy compounds, bisphenol A-type epoxy compounds, bisphenol F-type epoxy compounds, bisphenol S-type epoxy compounds, phenol novolac-type epoxy compounds, biphenyl-type epoxy compounds, dicyclopentadiene-type epoxy compounds, epoxy compounds of condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, triglycidyl isocyanurates, alicyclic epoxy compounds, and the like.

[0044] Among the above, it is preferable that epoxy compound (C) includes at least one selected from the group consisting of naphthalene-type epoxy compounds, dicyclopentadiene-type epoxy compounds, and biphenyl-type epoxy compounds. In this case, the glass transition temperature and flame retardancy of the cured product of the resin composition (M) can be increased. Epoxy compound (C) may be contained in the resin composition (M) as a single type or as two or more types.

[0045] Furthermore, epoxy compound (C) does not contain a phosphorus atom in its molecule. In other words, epoxy compound (C) does not contain phosphorus-containing epoxy compounds.

[0046] The proportion of epoxy compound (C) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total amount of resin components. The proportion of epoxy compound (C) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the total amount of resin components. Within the above range, the adhesion and heat resistance of the cured resin composition (M) to metals and glass can be improved.

[0047] <Phosphorus-containing compound> The resin composition (M) contains a phosphorus-containing compound (D). The phosphorus-containing compound (D) can enhance flame retardancy. The phosphorus-containing compound (D) is an organophosphorus compound containing one or more phosphorus atoms in one molecule. The phosphorus-containing compound (D) includes a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2). In this way, by using both the reactive phosphorus-containing compound (D1) and the unreacted phosphorus-containing compound (D2) in the resin composition (M), a low coefficient of thermal expansion, high adhesion, and excellent flame retardancy can be achieved in the cured product of the resin composition (M).

[0048] The reactive phosphorus-containing compound (D1) has a reactive group. This reactive group can react with the maleimide compound (A), the benzoxazine compound (B), and the epoxy compound (C) to form a crosslinked (cured) structure. The reactive groups can also react with each other. Therefore, the reactive phosphorus-containing compound (D1) can achieve both a low coefficient of thermal expansion and high adhesion in the cured product of the resin composition (M).

[0049] The reactive phosphorus-containing compound (D1) preferably has at least one reactive group selected from the group consisting of a carbon-carbon unsaturated double bond group, a hydroxyl group, a maleimide group, and a maleic anhydride group. In this case, the reactive phosphorus-containing compound (D1) may have high reactivity with the maleimide compound (A), the benzoxazine compound (B), and the epoxy compound (C), thereby lowering the coefficient of thermal expansion of the cured resin composition (M) and improving adhesion. Examples of carbon-carbon unsaturated double bond groups that the reactive phosphorus-containing compound (D1) may have include allyl groups, vinyl groups, 1-propenyl groups, allylphenyl groups, vinylphenyl groups, allylbenzyl groups, and vinylbenzyl groups.

[0050] The reactive phosphorus-containing compound (D1) preferably has at least one phosphorus atom-containing structure selected from the group consisting of the structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure. In this case, the phosphorus content of the resin composition (M) is increased, which can improve the flame retardancy of the cured product. Furthermore, since the cured product of the resin composition (M) has a rigid structure, the glass transition temperature can be increased.

[0051]

[0052] In equation (1), * indicates a coupling.

[0053] Among the above, it is more preferable that the reactive phosphorus-containing compound (D1) has a structure represented by formula (1) as a phosphorus atom-containing structure and a carbon-carbon unsaturated double bond group represented by formula (2) as a reactive group. In this case, the phosphorus content of the resin composition (M) is increased, which can further enhance the flame retardancy of the cured product. Also, since the cured product of the resin composition (M) has a more rigid structure, the glass transition temperature can be increased. Furthermore, the reactivity of the reactive phosphorus-containing compound (D1) with the maleimide compound (A), the benzoxazine compound (B), and the epoxy compound (C) is increased, which can improve the adhesion of the cured product of the resin composition (M).

[0054]

[0055] In equations (1) and (2), * indicates a coupling.

[0056] Unlike the reactive phosphorus-containing compound (D1), the unreacted phosphorus-containing compound (D2) exists in the resin composition (M) without reacting with other components. The unreacted phosphorus-containing compound (D2) can particularly enhance flame retardancy.

[0057] The unreacted phosphorus-containing compound (D2) preferably has at least one phosphorus atom-containing structure selected from the group consisting of the structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure. In this case, the phosphorus content of the resin composition (M) is increased, which can improve the flame retardancy of the cured product.

[0058]

[0059] In equation (1), * indicates a coupling.

[0060] Among the above, it is more preferable that the unreacted phosphorus-containing compound (D2) has a phosphine oxide structure as the phosphorus atom-containing structure. Examples of such compounds include diphenylphosphine oxide, xylylene bis-diphenylphosphine oxide, dimethyl phosphonate, trimethyl phosphonoacetate, diethyl cyanomethylphosphonate, 2-phosphonobutane-1,2,4-tricarboxylic acid, 3-methyl-1-phenyl-2-phosphorene-1-oxide, phenylphosphonic acid dichloride, diethylphosphonoacetate tert-butyl, tetraisopropyl methylenediphosphonate, diphenylphosphinic acid chloride, triphenylphosphine oxide, 2-fluoro-2-phosphonoacetate triethyl, vinylphosphonic acid, diethylphosphonoacetate methyl, and phenylphosphinic acid.

[0061] The unreacted phosphorus-containing compound (D2) is more preferably a phosphine oxide structure represented by formula (3) as a phosphorus atom-containing structure. In this case, both high adhesion and excellent flame retardancy of the cured resin composition (M) can be achieved.

[0062]

[0063] In formula (3), X represents a monovalent or divalent hydrocarbon group or alkylene group containing one or more aromatic rings, and n represents 1 or 2.

[0064] The mass ratio of the phosphorus-containing compound (D) to the maleimide compound (A) (mass of phosphorus-containing compound (D) / mass of maleimide compound (A), hereinafter also referred to as "mass ratio (R2)") is preferably 0.2 or higher, more preferably 0.25 or higher, and even more preferably 0.3 or higher. In this case, the flame retardancy of the cured resin composition (M) can be increased. The mass ratio (R2) is preferably 0.6 or lower, more preferably 0.55 or lower, and even more preferably 0.5 or lower. In this case, the coefficient of linear expansion of the cured resin composition (M) can be lowered, and the adhesion can be increased.

[0065] The mass ratio of the phosphorus-containing compound (D) to the benzoxazine compound (B) (mass of phosphorus-containing compound (D) / mass of benzoxazine compound (B), hereinafter also referred to as "mass ratio (R3)") is preferably 0.3 or higher, more preferably 0.35 or higher, and even more preferably 0.4 or higher. In this case, the flame retardancy of the cured resin composition (M) can be increased. The mass ratio (R3) is preferably 1.2 or lower, more preferably 1.1 or lower, and even more preferably 1.0 or lower. In this case, the coefficient of linear expansion of the cured resin composition (M) can be lowered, and the adhesion can be increased.

[0066] The mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) (mass of reactive phosphorus-containing compound (D1) / mass of unreacted phosphorus-containing compound (D2), hereinafter also referred to as "mass ratio (R4)") is preferably 0.5 or higher, more preferably 0.7 or higher, and even more preferably 1.0 or higher. If the mass ratio (R4) is less than 0.5, the adhesion of the cured resin composition (M) may decrease. The mass ratio (R4) is preferably 5.0 or lower, more preferably 4.5 or lower, and even more preferably 4.0 or lower. If the mass ratio (R4) is greater than 5.0, the flame retardancy of the cured resin composition (M) may decrease.

[0067] <Elastomer> The resin composition (M) may further contain an elastomer (E). The elastomer (E) can adjust the cured product of the resin composition (M) to an appropriate coefficient of linear thermal expansion. This is because the elastomer (E) has sufficient dispersibility in the resin composition (M) and can impart flexibility to the cured product of the resin composition (M).

[0068] The elastomer (E) is not particularly limited, but examples include styrene-butadiene resin, butadiene resin, isoprene resin, silicone resin, acrylic resin, methacrylic resin, styrene resin, etc. The elastomer (E) may contain only one type or two or more types. The elastomer (E) does not contain phosphorus atoms in its molecule.

[0069] The elastomer (E) can be determined by its properties, in addition to providing flexibility, based on the desired properties of the resin composition (M). For example, improving dielectric properties can be achieved by selecting an elastomer with nonpolar groups.

[0070] The elastomer (E) content is preferably 5% by mass or more relative to the total amount of the resin composition (M). The elastomer (E) content is preferably 20% by mass or less relative to the total amount of the resin composition (M). Within the above range, the coefficient of linear expansion of the cured product of the resin composition (M) can be made suitable.

[0071] <Other Components> The resin composition (M) may contain other components different from the above components, to the extent that they do not impair the effects of the present disclosure.

[0072] Other components are not limited to those mentioned above, but include, for example, thermosetting compounds other than the resin components, inorganic fillers, curing accelerators, polymerization initiators, colorants, coupling agents, heat stabilizers, antioxidants, defoamers, antistatic agents, dyes, pigments, polymerization inhibitors, lubricants, etc.

[0073] Thermosetting compounds other than the resin components mentioned above are selected based on desired physical properties such as heat resistance and electrical properties. Examples of such thermosetting resins include phenolic compounds.

[0074] Phenolic compounds are compounds having one or more phenolic hydroxyl groups in one molecule. Phenolic compounds can improve the heat resistance of the cured product of the resin composition (M).

[0075] The phenolic compounds are not particularly limited, but examples include biphenylaralkyl type phenolic resins, phenylaralkyl type phenolic resins, novolac type phenolic resins, cresol novolac type phenolic resins, bisphenol A novolac type phenolic resins, naphthalene type phenolic resins, and tetrakisphenol type phenolic resins. Note that phenolic compounds do not contain phosphorus atoms in their molecules. In other words, phenolic compounds do not contain phosphorus-containing phenolic compounds.

[0076] The phenol compound content is preferably 1 part by mass or more per 100 parts by mass of the total of the maleimide compound (A), the benzoxazine compound (B), and the epoxy compound (C). The phenol compound content is preferably 10 parts by mass or less per 100 parts by mass of the total of the maleimide compound (A), the benzoxazine compound (B), and the epoxy compound (C). Within the above range, the reactivity between the phenol compound and the benzoxazine compound (B) and the epoxy compound (C) is increased, which can raise the glass transition temperature of the cured resin composition (M).

[0077] Inorganic fillers are components that can lower the coefficient of thermal expansion. While not particularly limited, examples of inorganic fillers include silica such as synthetic silica, fused silica, or crystalline silica, talc, boehmite, magnesium hydroxide, aluminum hydroxide, aluminum silicate, magnesium silicate, zinc molybdate, calcium molybdate, clay, and mica.

[0078] The inorganic filler contained in the resin composition (M) may be one type or two or more types. Among these, it is preferable that the inorganic filler contains silica. In this case, the coefficient of linear expansion of the cured product of the resin composition (M) can be reduced.

[0079] The inorganic filler 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.

[0080] The inorganic filler content is preferably 80 parts by mass or more per 100 parts by mass of the resin component. The inorganic filler content is preferably 180 parts by mass or less per 100 parts by mass of the resin component. Within the above range, the coefficient of linear expansion of the cured product of the resin composition (M) can be lowered and the elastic modulus can be increased.

[0081] The curing accelerator acts catalytically on the curing (crosslinking) reaction of the resin composition (M), thereby accelerating the reaction. When the resin composition (M) contains a curing accelerator, the type and amount of the curing accelerator are appropriately adjusted according to the content and type of the resin components.

[0082] 2.2 Uses of Resin Compositions <Prepreg> Figure 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment. The prepreg 1 comprises a resin composition (M) or a semi-cured product of the resin composition (M) and a fibrous substrate 12. The prepreg 1 may also include a resin layer 11, as shown in Figure 1. That is, the resin layer 11 contains the resin composition (M) or a semi-cured product of the resin composition (M). In other words, the prepreg 1 may include a resin layer 11 in which the fibrous substrate 12 is impregnated with the resin composition (M) or a semi-cured product of the resin composition (M). The prepreg 1 may also have one fibrous substrate 12, or it may have two or more fibrous substrates 12.

[0083] The thickness of the fibrous substrate 12 is not particularly limited, but for example, it is 5 μm or more and 300 μm or less. In this case, it is possible to easily manufacture an electronic component embedded substrate from the prepreg 1.

[0084] The fibrous base material 12 is a reinforcing material and is not particularly limited, but examples include glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, linter paper, etc. Preferably, the glass cloth types are #7628, #1501, #2116, #1080, #1078, and #106. The glass cloth contains glass fibers, but may also contain reinforcing fibers other than glass fibers. The glass cloth may be surface-treated with a coupling agent or the like before being impregnated with the resin composition (M) of Stage A. Surface treatment of the glass cloth can improve the adhesion between the glass cloth and the resin composition (M). The coupling agent used for surface treatment is not particularly limited, but examples include those that can be used with the inorganic filler described above.

[0085] The prepreg 1 is manufactured by impregnating a fibrous substrate 12 with a resin composition (M). The impregnation method can be, for example, by immersing the fibrous substrate 12 in a varnish-like resin composition (M), or by applying the varnish-like resin composition (M) to the fibrous substrate 12. The varnish-like resin composition (M) is a state in which the resin composition (M) is dissolved in an organic solvent.

[0086] When using a varnish-state resin composition (M), the fibrous substrate 12 impregnated with the resin composition (M) may be heated to reduce or remove organic solvents. For example, the heating conditions may be a temperature of 80°C to 180°C and a duration of 1 minute to 10 minutes.

[0087] The method for manufacturing the prepreg 1 according to this embodiment is not limited to the method described above. That is, the prepreg 1 according to this embodiment can be manufactured by any suitable method.

[0088] <Resin-Coated Film> Figure 2 is a schematic cross-sectional view showing an example of a resin-coated film 2 according to an embodiment. The resin-coated film 2 comprises a resin layer 21 containing a resin composition (M) or a semi-cured product of the resin composition (M), and a support film 22. Therefore, an insulating substrate can be formed by heating the resin layer 21. The resin-coated film 2 may further include other layers between the resin layer 21 and the support film 22 that overlaps the resin layer 21.

[0089] The resin layer 21 may or may not contain a fibrous substrate (not shown). If the resin layer 21 contains a fibrous substrate, the same type of fibrous substrate as the fibrous substrate 12 of the prepreg 1 can be used. In other words, the resin layer 21 may be manufactured from the prepreg 1.

[0090] The support film 22 supports the resin layer 21. The support film 22 makes the resin layer 21 easier to handle. The support film 22 is not particularly limited, but for example, it is an electrically insulating film. Examples of support films 22 include polyethylene terephthalate (PET) film, polyimide film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, polyarylate film, and the like.

[0091] A release agent layer (not shown) may be provided on the surface of the support film 22 that supports the resin layer 21. This release agent layer allows the support film 22 to be peeled off from the resin layer 21 as needed. Preferably, the support film 22 is peeled off from the insulating layer after the resin layer 21 has been cured to form an insulating layer.

[0092] In Figure 2, one side of the resin layer 21 is covered by the support film 22, but the other side of the resin layer 21 may be covered by a cover film (not shown). Covering both sides of the resin layer 21 makes it easier to handle and prevents foreign matter from adhering to the resin layer 21. The cover film is not particularly limited, but for example, it is an electrically insulating film. Examples of cover films include polyethylene terephthalate (PET) film, polyolefin film, polyester film, and polymethylpentene film. Furthermore, a release agent layer may be provided between the resin layer 21 and the cover film. The release agent layer allows the cover film to be peeled off from the resin layer 21 as needed.

[0093] The resin layer 21 is manufactured by applying a resin composition (M) to the support film 22. The method of applying the resin composition (M) is not particularly limited, but for example, a bar coater, die coater, doctor blade, baker applicator, etc., can be used. When applying the resin layer 21 to the support film 22, it is preferable to use a resin composition (M) in a varnish state. In addition, the varnish-state resin composition (M) applied on the support film 22 may be heated in order to reduce or remove organic solvents. The heating conditions are, for example, the same as those for the prepreg 1. In this way, a resin layer 21 containing the resin composition (M) or a semi-cured product of the resin composition (M) is formed on the support film 22, thereby manufacturing a resin-coated film 2.

[0094] The method for manufacturing the resin-coated film 2 according to the embodiment is not limited to the method described above. In other words, the resin-coated film 2 according to the embodiment can be manufactured by any suitable method.

[0095] <Resin-Coated Metal Foil> Figure 3 is a schematic cross-sectional view showing an example of a resin-coated metal foil 3 according to an embodiment. The resin-coated metal foil 3 comprises a resin layer 31 containing a resin composition (M) or a semi-cured product of the resin composition (M), and a metal foil 32. Therefore, an insulating substrate can be formed by heating the resin layer 31. The resin-coated metal foil 3 may also include other layers between the resin layer 31 and the metal foil 32 overlapping the resin layer 31.

[0096] The resin layer 31 may or may not contain a fibrous substrate (not shown). If the resin layer 31 contains a fibrous substrate, the same type of fibrous substrate as the fibrous substrate 12 of the prepreg 1 can be used. In other words, the resin layer 31 may be manufactured from the prepreg 1.

[0097] The metal foil 32 is not particularly limited, but examples include copper foil and aluminum foil. The metal foil 32 can be used as wiring 52 of the wiring board 5 after unnecessary portions are removed by etching using a subtractive method or the like.

[0098] The resin-coated metal foil 3 may be equipped with a cover film (not shown) or the like, if necessary. The same cover film used for the resin-coated film 2 described above can be used.

[0099] The resin layer 31 is manufactured by applying a resin composition (M) to the metal foil 32. The method of applying the resin composition (M) is not particularly limited, but for example, a bar coater, die coater, doctor blade, baker applicator, etc. are used. When applying the resin composition (M) to the metal foil 32, it is preferable to use the resin composition (M) in a varnish state. In addition, the varnish-state resin composition (M) applied on the metal foil 32 may be heated in order to reduce or remove organic solvents. The heating conditions are, for example, the same as those for the prepreg 1. In this way, a resin layer 31 containing the resin composition (M) or a semi-cured product of the resin composition (M) is formed on the metal foil 32, thereby manufacturing the resin-coated metal foil 3.

[0100] The method for manufacturing the resin-coated metal foil 3 according to the embodiment is not limited to the method described above. That is, the resin-coated metal foil 3 according to the embodiment can be manufactured by any appropriate method.

[0101] <Metal-clad laminate> Figure 4 is a schematic cross-sectional view showing an example of a metal-clad laminate 4 according to an embodiment. The metal-clad laminate 4 comprises an insulating layer 41 containing a cured product of a resin composition (M) and a metal foil 42.

[0102] One example of a method for manufacturing the metal-clad laminate 4 is to layer a resin composition (M) or a semi-cured product of the resin composition (M) with a metal foil 42, heat and pressurize to cure the resin composition (M) and form an insulating layer 41. More specifically, a metal foil 42 such as copper foil is layered on one or both sides of the resin composition (M) or a semi-cured product of the resin composition (M), the resin composition (M) or the semi-cured product of the resin composition (M) and the metal foil 42 are heated and pressurized to cure the resin composition (M) and form an insulating layer 41, and the insulating layer 41 containing the cured resin composition (M) and the metal foil 42 are laminated and integrated to produce a metal-clad laminate 4 in which the metal foil 42 is in close contact with one or both sides of the insulating layer 41 containing the cured resin composition (M).

[0103] The insulating layer 41 may also be manufactured using prepreg 1. More specifically, the insulating layer 41 can be formed by heating and pressing the prepreg 1 and metal foil 42 together to cure the prepreg 1, and then laminating and integrating the insulating layer 41 containing the cured prepreg 1 and the metal foil 42, thereby manufacturing a metal-clad laminate 4 in which the metal foil 42 is in close contact with one or both sides of the insulating layer 41 containing the cured prepreg 1. When the metal-clad laminate 4 is manufactured using prepreg 1, it has a fibrous base material (not shown) within the insulating layer 41. There may be only one fibrous base material, or there may be two or more.

[0104] Furthermore, the insulating layer 41 may be manufactured using a resin-coated film 2 and a resin-coated metal foil 3. More specifically, the resin layer 21 of the resin-coated film 2 or the resin layer 31 of the resin-coated metal foil 3 and the metal foil 42 are heated and pressurized to cure the resin layer 21 of the resin-coated film 2 or the resin layer 31 of the resin-coated metal foil 3 to form an insulating layer 41. By laminating and integrating the insulating layer 41, which includes the cured resin layer 21 of the resin-coated film 2 or the cured resin layer 31 of the resin-coated metal foil 3, with the metal foil 42, a metal-clad laminate 4 can be manufactured in which the metal foil 42 is adhered to one or both sides of the insulating layer 41, which includes the cured resin layer 21 of the resin-coated film 2 or the cured resin layer 31 of the resin-coated metal foil 3. In this case, when manufactured using a resin-coated metal foil 3, the metal foil 32 of the resin-coated metal foil 3 becomes the metal foil 42 in the metal-clad laminate 4.

[0105] When manufacturing the metal-clad laminate 4, the thickness of the metal foil 42 can be appropriately set according to the desired purpose. Furthermore, the heating and pressing conditions when manufacturing the metal-clad laminate 4 can be appropriately set depending on the thickness of the metal-clad laminate 4 to be manufactured and the type and components of the resin composition (M) that forms the insulating layer 41. In addition, when using an ultra-thin metal foil as the metal foil 42, a metal foil with a carrier equipped with a release layer and carrier may be used to improve handling.

[0106] The method for manufacturing the metal-clad laminate 4 according to this embodiment is not limited to the method described above. In other words, the metal-clad laminate 4 according to this embodiment can be manufactured by any suitable method.

[0107] <Wiring Board> Figure 5 is a schematic cross-sectional view showing an example of a wiring board 5 according to the embodiment. The wiring board 5 comprises an insulating layer 51 containing a cured resin composition (M) and wiring 52. The wiring 52 may be formed on only one side of the insulating layer 51, or on both sides.

[0108] The insulating layer 51 may include a cured product of the prepreg 1. That is, the wiring board 5 comprises an insulating layer 51 manufactured using the prepreg 1 and wiring 52 overlapping the insulating layer 51. The wiring 52 may be formed on only one side of the insulating layer 51 or on both sides. When the wiring board 5 is manufactured using the prepreg 1, it has a fibrous base material (not shown). There may be only one fibrous base material or two or more.

[0109] Furthermore, the wiring board 5 may be manufactured using the metal-clad laminate 4 described above. More specifically, the wiring 52 can be formed by etching or the like on the metal foil 42 on the surface of the metal-clad laminate 4. That is, the wiring board 5 can be formed by partially removing the metal foil 42 on the surface of the metal-clad laminate 4. In this way, a wiring board 5 can be manufactured that comprises an insulating layer 51 and wiring 52 as circuits on one or both sides of the insulating layer 51.

[0110] Furthermore, while not limited to the methods described above, other methods for circuit formation include, for example, circuit formation using the semi-additive process (SAP) and the modified semi-additive process (MSAP).

[0111] 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.

[0112] The resin composition (M) according to the first embodiment contains a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D). The phosphorus-containing compound (D) includes a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2). The mass ratio (R4) of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is 0.5 or more and 5.0 or less.

[0113] According to this embodiment, it is possible to achieve a low coefficient of linear thermal expansion, high adhesion, and excellent flame retardancy of the cured resin composition (M).

[0114] In the second embodiment, the resin composition (M) has a mass ratio (R2) of phosphorus-containing compound (D) to maleimide compound (A) of 0.2 or more and 0.6 or less, according to the first embodiment.

[0115] In the third embodiment, the resin composition (M) has a mass ratio (R3) of phosphorus-containing compound (D) to benzoxazine compound (B) of 0.3 or more and 1.2 or less, according to the first or second embodiment.

[0116] The resin composition (M) according to the fourth embodiment, in any one of the first to third embodiments, has at least one reactive phosphorus-containing compound (D1) selected from the group consisting of a carbon-carbon unsaturated double bond group, a hydroxyl group, a maleimide group, and a maleic anhydride group.

[0117] The resin composition (M) according to the fifth embodiment, in any one of the first to fourth embodiments, has at least one reactive phosphorus-containing compound (D1) selected from the group consisting of a structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure.

[0118]

[0119] In equation (1), * indicates a coupling.

[0120] The resin composition (M) according to the sixth embodiment, in any one of the first to fifth embodiments, has at least one unreacted phosphorus-containing compound (D2) selected from the group consisting of a structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure.

[0121]

[0122] In equation (1), * indicates a coupling.

[0123] The resin composition (M) according to the seventh embodiment, in any one of the first to sixth embodiments, has a reactive phosphorus-containing compound (D1) having a structure represented by formulas (1) and (2).

[0124]

[0125] In equations (1) and (2), * indicates a coupling.

[0126] The resin composition (M) according to the eighth embodiment, in any one of the first to seventh embodiments, has an unreacted phosphorus-containing compound (D2) having a structure represented by formula (3).

[0127]

[0128] In formula (3), X represents a monovalent or divalent hydrocarbon group or alkylene group containing one or more aromatic rings, and n represents 1 or 2.

[0129] The resin composition (M) according to the ninth embodiment is such that, in any one of the first to eighth embodiments, the benzoxazine compound (B) has a carbon-carbon unsaturated double bond group.

[0130] The resin composition (M) according to the tenth embodiment further contains an elastomer (E) in any one of the first to ninth embodiments.

[0131] The resin composition (M) according to the eleventh embodiment, in any one of the first to tenth embodiments, comprises at least one epoxy compound (C) selected from the group consisting of biphenyl-type epoxy compounds, naphthalene-type epoxy compounds, and dicyclopentadiene-type epoxy compounds. The proportion of epoxy compound (C) is 5% by mass or more and 50% by mass or less, based on the total amount of resin components.

[0132] The prepreg (1) according to the twelfth embodiment comprises a resin composition (M) or a semi-cured product of a resin composition (M) according to any one of the first to eleventh embodiments, and a fibrous substrate (12).

[0133] The resin-coated film (2) according to the 13th embodiment comprises a resin layer (21) containing a resin composition (M) or a semi-cured product of the resin composition (M) according to any one of the first to 11 embodiments, and a support film (22).

[0134] The resin-coated metal foil (3) according to the 14th embodiment comprises a resin layer (31) containing a resin composition (M) or a semi-cured product of the resin composition (M) according to any one of the first to 11 embodiments, and a metal foil (32).

[0135] The metal-clad laminate (4) according to the 15th embodiment comprises an insulating layer (41) containing a cured product of a resin composition (M) according to any one of the first to 11 embodiments, and a metal foil (42).

[0136] The wiring board (5) according to the 16th embodiment comprises an insulating layer (51) containing a cured product of a resin composition (M) according to any one of the first to 11 embodiments, and wiring (52).

[0137] The metal-clad laminate (4) according to the 17th embodiment comprises an insulating layer (41) containing a cured product of the prepreg (1) according to the 12th embodiment, and a metal foil (42).

[0138] The wiring board (5) according to the 18th embodiment comprises an insulating layer (51) containing a cured product of the prepreg (1) according to the 12th embodiment, and wiring (52).

[0139] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the examples.

[0140] 1. Preparation of Evaluation Samples (Preparation of Resin Composition) Each component was blended in the amounts shown in Table 1, and methyl ethyl ketone (MEK) was used as the solvent. The mixture was stirred and mixed until homogenized, resulting in a varnish-like resin composition with a solid content concentration of 40-50% by mass. Details of the components used are as follows. - Maleimide compound: Manufactured by Yamato Chemical Industries, Ltd., product name; BMI-5100 - Benzooxazine compound: Manufactured by Shikoku Chemicals, Ltd., product name; ALP-d, a bifunctional benzooxazine compound having an allyl group - Epoxy compound: Manufactured by Nippon Kayaku Co., Ltd., product name; NC-3500, polyfunctional biphenylaralkyl type - Phenol compound: Manufactured by DIC Corporation, product name; TD-2090, novolac type - Elastomer: Manufactured by Nagase ChemteX Corporation, product name; PASR-001, epoxy-modified acrylic rubber elastomer - Reactive phosphorus-containing compound: Manufactured by Sanko Co., Ltd., product name; SD-5, a phosphorus-containing compound containing structures represented by formulas (1) and (2) - Unreacted phosphorus-containing compound: Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name; PQ-60, a phosphorus-containing compound represented by formula (3) where n is 2 and X is a paraxylylene group - Curing accelerator: Manufactured by Shikoku Chemicals Co., Ltd., product name: 2E4MZ, imidazole compound - Polymerization initiator: Manufactured by NOF Corporation, product name: Perbutyl P - Inorganic filler #1: Manufactured by Kawai Lime Industry Co., Ltd., product name: ALH-F, aluminum hydroxide filler - Inorganic filler #2: Manufactured by Admatex Co., Ltd., product name: SC2050, silica filler.

[0141] (Prepreg preparation) As a fibrous base material, glass cloth (manufactured by Nanya Co., Ltd., product name "#7628") was used. The above-mentioned varnished resin composition was impregnated into this glass cloth at room temperature, and then heated at approximately 150°C for 4 to 5 minutes using a non-contact heating unit to dry out and remove the solvent in the varnish, thereby partially curing the resin composition and producing a prepreg. The proportion of the resin composition contained in the prepreg was adjusted to 45% by mass.

[0142] (Preparation of metal-clad laminate) Ten of the above prepregs are stacked, and these prepregs are used as metal foil, sandwiched between the roughened surfaces of two copper foils (35 μm thick), and heated at 220°C and 2.94 MPa (30 kgf / cm²). ２By heating and pressurizing the material for 90 minutes, a metal-clad laminate with an overall insulating layer thickness of approximately 1030 μm was fabricated.

[0143] 2. Evaluation (Coefficient of Linear Expansion) The copper foil of the above metal-clad laminate was removed by etching to obtain an unclad plate. Using this unclad plate as a test specimen, the coefficient of linear expansion (CTE) was measured by the Thermal Mechanical Analysis Method (TMA) based on IPC TM650 2.4.41. A coefficient of linear expansion of 6.2 ppm / °C or less was evaluated as good, and a value greater than 6.2 ppm / °C was evaluated as poor.

[0144] (Metal Peel Strength) The metal peel strength of the above-mentioned metal-clad laminate was measured by examining the adhesion of copper foil in accordance with the peel strength of JIS C6481. A metal peel strength of 0.50 or higher was evaluated as good, and a value below 0.50 was evaluated as poor.

[0145] (Flame Retardancy) Flame retardancy was evaluated by conducting a UL94 combustion test. Specifically, the copper foil of the above-mentioned metal-clad laminate was removed by etching to obtain an unclad plate. From this unclad plate, strip-shaped test pieces measuring 125 mm in length and 12.5 mm in width were cut out. These test pieces were mounted vertically on a clamp, and two 10-second indirect flame tests were performed using a 20 mm flame. The combustion behavior was then judged as V-0, V-1, V-2, or Not. Flame retardancy was evaluated as good if V-0, and poor otherwise.

[0146]

[0147] 1. Prepreg 2. Resin-coated film 3. Resin-coated metal foil 4. Metal-clad laminate 5. Wiring board

Claims

1. A resin composition comprising a maleimide compound (A), a benzoxazine compound (B), an epoxy compound (C), and a phosphorus-containing compound (D), wherein the phosphorus-containing compound (D) comprises a reactive phosphorus-containing compound (D1) and an unreacted phosphorus-containing compound (D2), and the mass ratio of the reactive phosphorus-containing compound (D1) to the unreacted phosphorus-containing compound (D2) is 0.5 or more and 5.0 or less.

2. The resin composition according to claim 1, wherein the mass ratio of the phosphorus-containing compound (D) to the maleimide compound (A) is 0.2 or more and 0.6 or less.

3. The resin composition according to claim 1, wherein the mass ratio of the phosphorus-containing compound (D) to the benzoxazine compound (B) is 0.3 or more and 1.2 or less.

4. The resin composition according to claim 1, wherein the reactive phosphorus-containing compound (D1) has at least one selected from the group consisting of a carbon-carbon unsaturated double bond group, a hydroxyl group, a maleimide group, and a maleic anhydride group.

5. The reactive phosphorus-containing compound (D1) has at least one selected from the group consisting of a structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure, in formula (1), * represents a bond, the resin composition according to claim 1.

6. The unreacted phosphorus-containing compound (D2) has at least one selected from the group consisting of the structure represented by formula (1), a phosphine oxide structure, and a phosphazene structure. The resin composition according to claim 1, wherein * represents a bonding bond in formula (1).

7. The reactive phosphorus-containing compound (D1) has the structures represented by formulas (1) and (2), The resin composition according to claim 1, wherein in formulas (1) and (2), * indicates a bonding bond.

8. The unreacted phosphorus-containing compound (D2) has a structure represented by formula (3), The resin composition according to claim 1, wherein in formula (3), X represents a monovalent or divalent hydrocarbon group or alkylene group containing one or more aromatic rings, and n represents 1 or 2.

9. The resin composition according to claim 1, wherein the benzoxazine compound (B) has a carbon-carbon unsaturated double bond group.

10. The resin composition according to claim 1, further comprising elastomer (E).

11. The resin composition according to claim 1, wherein the epoxy compound (C) comprises at least one selected from the group consisting of biphenyl-type epoxy compounds, naphthalene-type epoxy compounds, and dicyclopentadiene-type epoxy compounds, and the proportion of the epoxy compound (C) is 5% by mass or more and 50% by mass or less with respect to the total amount of the resin components.

12. A prepreg comprising a resin composition according to any one of claims 1 to 11 or a semi-cured product of the resin composition, and a fibrous substrate.

13. A resin-coated film comprising a resin layer containing the resin composition described in any one of claims 1 to 11 or a semi-cured product of the resin composition, and a support film.

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

15. A metal-clad laminate comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 11, and a metal foil.

16. A wiring board comprising an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 11, and wiring.

17. A metal-clad laminate comprising an insulating layer containing a cured prepreg according to claim 12, and a metal foil.

18. A wiring board comprising an insulating layer containing a cured prepreg according to claim 12, and wiring.

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