It minds the pattern mask for exposure

摘要

PROBLEM TO BE SOLVED: To obtain a lead frame with good quality, by preventing its lead portion, etc., from deforming when peeling its resist film therefrom in the case of using a photoetching method. ;SOLUTION: As this method, first, subjecting a photosensitive resin layer formed on the surface of a metallic raw material 1 to a pattern exposure via an exposure pattern mask, its development and hard-film processing are performed thereafter to change it into a resist film 2 with metallic surfaces exposed partially to the outside after a predetermined pattern. Then, an etching processing is applied to the metallic raw material 1. Thereafter, the resist film 2 is peeled from the metallic raw material 1. In this case, the hard-film processing is so performed as to bake the photosensitive resin layer at an atmospheric temperature of 135-165°C after contacting with it a chromic acid solution having a chromic anhydride concentration of 5-6wt.%.;COPYRIGHT: (C)1998,JPO