HEAT CURABLE RESIN COMPOSITION, OVERCOATING AGENT FOR FLEXIBLE CIRCUIT BOARD, AND SURFACE PROTECTIVE FILM

摘要

Overcoating agents and thermosetting resin compositions of the invention give protective layers that have excellent adhesion to substrates and in particular to tin, excellent long-term reliability of electric insulation and small warpage. A thermosetting resin composition according to the invention includes a carboxyl group-containing urethane resin (A), a curing agent (B) and an acid anhydride (C) as essential components. A flexible circuit board overcoating agent includes the thermosetting resin composition. A surface protective layer of the invention comprises a cured product of the thermosetting resin composition.