PURPOSE: To effectively obtain a two-layered TAB exerting no influence upon heating at the time of semiconductor element mounting, while compensating mechanical strength of inner leads, by performing etching while an outer lead part and a sprocket part are irradiated from the insulating layer side of a two-layered TAB original sheet, with a light having an ultraviolet wavelength region.
CONSTITUTION: A two-layered TAB original sheet is obtained by forming a copper layer 11 on a polyimide film 10. After a resist layer 12 is formed on the polyimide film 10, said resist layer 12 is exposed to light by using a photo mask having patterns of a sprocket hole part 30, an inner lead part 31 and an outer lead part 32, and then developed, thus forming a resist mask 13. While the sprocket hole part 30 and the outer lead part 32 are irradiated with ultraviolet rays by using a high pressure mercury lamp, etching is performed. The resist layer 13 is eliminated, and the sprocket hole part 30 and the outer lead part 32 are completely etched, thereby obtaining a two-layered TAB wherein the inner lead part 31 of about 5μm in thickness is left.
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OTANI KENICHI
MUGISHIMA TOSHIO
