| abstract |
A wiring board capable of providing a protective film that is flexible, has good electrical insulation reliability, and has good adhesion to a flexible wiring board (that is, good adhesion to a polyimide film and a tin plating layer). A thermosetting composition for a protective film, a protective film for a wiring board obtained by curing the composition, and a flexible wiring board covered with the protective film are provided. Thermosetting for protective film of wiring board comprising epoxy group-containing compound having alkoxysilyl group in molecule, polyurethane having carboxyl group and structural unit represented by formula (1) and solvent as essential components Sex composition. (In the formula, R 1 represents an alkylene group having 3 to 18 carbon atoms, and n represents an integer of 1 or more.) [Selection figure] None |