Blank beam leads for IC chip bonding

Claim 1

In a blank for manufacturing an integrated circuit component lead frame, said blank comprising a flexible strip of electrically conductive metal, a layer of positive-working resist adhered to a portion of one surface of said metal strip, and a layer of negative-working resist adhered to a portion of the opposite surface of said metal strip said negative-working layer having a thickness sufficient to support leads formed from said metal strip the improvement wherein said negative-working resist comprises a binder, a photopolymerizable monomer portion, and a photoinitiator composition said binder comprising a mixture of at least (i) a polymer having recurring units with the structure ##STR5## wherein each Bu is butyl, and x, y and z are mole percents and are about 3≦ x≦70 30≦y≦60 1≦z≦5; and (ii) polymethylmethacrylate in an amount of from 0 to about 75 weight percent of the mixture; said binder having a glass transition temperature between about 50 and about 100° C.; said monomer portion being a compound selected from the group consisting of triethylene glycol diacrylate, tetraethylene glycol diacrylate, and a mixture of pentaerthyritol tetraacrylate and either 1,6-hexanediol diacrylate or tripropylene glycol diacrylate.