Patent ID: 6130027
Filing Date: 2000-10-10
Classification: G03F,H01L

Abstract:
A process for producing lead frames with a minimum of side etching which comprises the sequential steps of (a) coating a metal lead frame substrate with a first photosensitive film, (b) exposing the first photosensitive film to provide a patterned first photosensitive film, (c) developing the patterned first photosensitive film to provide openings therein, (d) partially etching the surface of the metal lead frame beneath the openings in the developed first photosensitive film, (e) coating the partially etched metal surface of the metal lead frame with a positive second photosensitive film, (f) exposing the positive second photosensitive film to light passing through the openings in the developed first photosensitive film, which functions as a mask, (g) developing the exposed second photosensitive film to provide openings therein, (h) performing fine etching of the metal lead frame substrate beneath the openings in the second photosensitive film to a desired depth at least once, and (i) removing said first and second photosensitive films.