Prepreg, metal foil-clad laminate, and printed wiring board

A prepreg obtained by impregnating or coating a base material (D) with a resin composition comprising:

• a naphthol-modified dimethylnaphthalene formaldehyde resin (A) having a hydroxyl equivalent of 300 to 600 n/eq.;
• an epoxy resin (B) having an epoxy equivalent of 250 to 350 g/eq.;
• and
• an inorganic filler (C),
• wherein the naphthol-modified dimethylnaphthalene formaldehyde resin (A) is obtained by condensing a dimethylnaphthalene formaldehyde resin and (c) a naphthol compound represented by the following general formula (1) in the presence of an acidic catalyst,
• wherein R1 and R2 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and
• the dimethylnaphthalene formaldehyde resin is obtained by condensing (a) at least one dimethylnaphthalene selected from the group consisting of 1,5-dimethylnaphthalene, 1,6-dimethylnaphthalene, 2,6-dimethylnaphthalene, 1,7-dimethylnaphthalene, 1,8-dimethylnaphthalene, and 2,7-dimethylnaphthalene and (b) formaldehyde in the presence of an acidic catalyst, the epoxy resin (B) is represented by the following formula (2):
• wherein n represents an integer of 1 or more,
• the inorganic filler (C) is silica,
• a content of the naphthol-modified dimethylnaphthalene formaldehyde resin (A) is 40 to 70 parts by mass based on 100 parts by mass in total of the naphthol-modified dimethylnaphthalene formaldehyde resin (A) and the epoxy resin (B),
• a content of the epoxy resin (B) is 30 to 60 parts by mass based on 100 parts by mass in total of the naphthol-modified dimethylnaphthalene formaldehyde resin (A) and the epoxy resin (B), and
• a content of the inorganic filler (C) is 5 to 300 parts by mass based on 100 parts by mass in total of the naphthol-modified dimethylnaphthalene formaldehyde resin (A) and the epoxy resin (B).