| abstract |
Provided is a protective film having a high adhesion and a raw material liquid from which the protective film can be obtained. This invention is a raw material liquid containing the polyimide resin component containing the polyimide resin represented by following General formula (1), a photosensitive agent, and a block isocyanate, and to the application object before the protective film of the wiring board 10 is formed, The raw material liquid is applied onto the surface on which the metal wiring film 12 of the coating object is disposed, and the solvent is evaporated by coating and drying to form a photopolymerizable film covering the metal wiring film 12, thereby exposing and developing. As a result, the photopolymerizable film is partially removed, cured by heating, and a protective film 13 is formed to cover other portions while partially exposing the metal wiring film 12, thereby obtaining the wiring board 10. It crosslinks after patterning, and adhesiveness with a metal film is high. <Formula (1)> [In Formula (1), R 1 and R 2 are each independently an alkylene group which may be substituted, m is an integer of 1 to 30, n is an integer of 0 to 20.] |