Thermosetting resin composition, coverlay film, adhesive sheet, and flexible printed wiring board

A thermosetting resin composition, comprising:

• a solid epoxy resin that is solid at 25° C.;
• a non-solid epoxy resin that is non-solid at 25° C.;
• particulate rubber dispersed in the non-solid epoxy resin;
• a curing agent;
• an inorganic filler;
• and
• polycarbonate diol-derived polyurethane,
• wherein
• when a total part by mass of the solid epoxy resin and the non-solid epoxy resin is 100 parts by mass, a content of the solid epoxy resin that is solid at 25° C. is from 60 to 85 parts by mass,
• when a total part by mass of the solid epoxy resin and the non-solid epoxy resin is 100 parts by mass, a content of the non-solid epoxy resin that is non-solid at 25° C. is from 15 to 40 parts by mass,
• when a total part by mass of the solid epoxy resin and the non-solid epoxy resin is 100 parts by mass, a content of the particulate rubber is from 3 to 15 parts by mass,
• an equivalent amount of a curing agent to one equivalent amount of an epoxy group of the solid epoxy resin and the non-solid epoxy resin is from 0.3 to 0.8 equivalents,
• when a total part by mass of the solid epoxy resin and the non-solid epoxy resin is 100 parts by mass, a content of the inorganic filler is from 60 to 150 parts by mass,
• when a total part by mass of the solid epoxy resin and the non-solid epoxy resin is 100 parts by mass, a content of the polycarbonate diol-derived polyurethane is from 50 to 100 parts by mass,
• a NCO/OH ratio of the polycarbonate diol-derived polyurethane at a time of synthesis is from 0.85 to 0.99;
• an acid value of the polycarbonate diol-derived polyurethane is from 10 to 30 mgKOH/g, and
• a weight average molecular weight of the polycarbonate diol-derived polyurethane is from 15,000 to 50,000.