PURPOSE: To provide a titled copper alloy which has excellent strength, heat resistance, and electrical and thermal conductivity, and has good bendability, plating adhesion and solderability, and of which the coefft. of thermal expansion exhibits the value roughly similar to the value of a conventional copper alloy by consisting the same of specifically composed Cr, Zn and Cu.
CONSTITUTION: A copper alloy contains 0.03W0.40wt% Cr and 0.03W0.75% Zn and consists of the balance Cu and is suitable as a lead frame material for semiconductor apparatus. Cr is precipitated as a microprecipitate in the Cu base material of said copper alloy and the excellent strength, heat resistance and conductivity as well as good plating adhesion, solderability, etc. are obtained by such precipitation plus the deoxidizing effect of Zn. The reason for limiting the above-mentioned compsn. of Cr and Zn lie in that, if the above-mentioned components are added at the lower limits or below, the necessary strength and heat resistance are unobtainable, and that if they are added at the upper limits or above, the electrical and thermal conductivity are reduced and the bendability, plating adhesion and solderability, etc. are deteriorated as well.
AKASAKA KIICHI
SHINOZAKI SHIGEO
