Abstract: A copper base alloy for terminals that is of the Cu-Ni-Sn-P or Cu-Ni-Sn-P-Zn system and that has a tensile strength of at least 50 kgf/mm.sup.2, a spring limit of at least 40 kgf/mm.sup.2, a stress relaxation of not more than 10% and a conductivity of at least 30% IACS is provided. Terminals the spring portion or the entire part of which is produced from that copper base alloy, having an insertion/extraction force of 0.2-3 kgf and a resistance of not more than 3 m.OMEGA. at low voltage and current as initial performance, with the added characteristic that the terminals will experience not more than 20% stress relaxation are also provided. The alloy is superior to the conventional bronze, phosphor bronze and Cu-Sn-Fe-P alloys for terminals in terms of tensile strength, spring limits, stress relaxation characteristic and conductivity and, hence, the terminals manufactured from those alloys have higher performance and reliability than the terminals made of the conventional copper base alloys for terminals.

Abstract: A copper base alloy for terminals that is superior in all aspects of tensile strength, spring limits, conductivity, and stress relaxation characteristics can be produced by a process repeating the cycles consisting of hot-rolling, cold-rolling and annealing, in which process an ingot is prepared by melting and casting an alloy containing 1.0-3.0 wt % Ni, 0.02-0.15 wt % P. 0.5-2.0 wt. % Sn and, as an optional component, 0.01-2.0 wt % Zn, with the balance being Cu and incidental impurities, and with the ratio of weight percentages of Ni to P being within the range of 10-50%.