PURPOSE: To sufficiently suppress the height of burrs generated at the time of executing punching from a thin sheet in an Fe-Ni alloy steel strip for a lead frame and to impart it with the coefficient of thermal expansion, corrosion resistance, solderability and plating properties not inferior to those of 42Ni-Fe.
CONSTITUTION: An Fe-Ni alloy for a lead frame having a compsn. contg., by weight, 32 to 35% Ni, 0.1 to 1.5% Cu and/or 0.1 to 1.5% Mo (where Cu+Mo: ≤1.5%) and S and/or P by 0.005 to 0.020% in total and in which the contents of Mg and Mn mixed as other components are suppressed to ≤0.005% and ≤1.0% as well is subjected to hot forging and rolling, is thereafter annealed and is furthermore subjected to cold rolling at about 30% draft to regulate its sheet thickness into a final one, which is subsequently annealed into a steel strip for a lead frame having ≤0.2mm sheet thickness. The height of burrs can be suppressed to about ≤0.025mm.
ISHIDA KAZUHISA
YAMASAKO YOSHIKAZU
