Patent ID: 7076868

Claim:
A method of manufacturing a wiring circuit board having bumps in which the bumps formed on the wiring circuit have a surface roughness on the tip faces thereof of 0.2 to 20 μm, the manufacturing method comprising the steps of: (a) laminating a protective film on a bump formation surface of a metal foil having a surface roughness of 0.2 to 20 μm and a thickness which is the sum of a thickness of the wiring circuit and a height of the bumps to be formed on the wiring circuit, and forming an etching mask for wiring circuit formation on a wiring circuit formation surface of the metal foil; (b) half etching the metal foil from the side of the etching mask for wiring circuit formation to form a wiring circuit with a desired thickness; (c) providing a cover coat layer on the wiring circuit after removing the etching mask for wiring circuit formation; (d) forming an etching mask for bump formation on the bump formation surface after removing the protective film provided on the bump formation surface of the metal foil; (e) half etching the metal foil from the side of the etching mask for bump formation to form bumps of the desired height; (f) forming a polyimide precursor layer to cover the bumps after removing the etching mask for bump formation; and (g) etching back the polyimide precursor layer and imidizing the same to form an insulating layer with a desired thickness.