A copper alloy having an improved combination of yield strength and electrical conductivity consists essentially of, by weight, from 1% to 2.5% of nickel, from 0.5% to 2.0% of cobalt, with a total nickel plus cobalt content of from 1.7% to 4.3%, from 0.5% to 1.5% of silicon with a ratio of (Ni+Co)/Si of between 3.5 and 6, and the balance copper and inevitable impurities wherein the wrought copper alloy has an electrical conductivity in excess of 40% IACS. A further increase in the combination of yield strength and electrical conductivity as well as enhanced resistance to stress relaxation is obtained by a further inclusion of up 1% of silver. A process to manufacture the alloys of the invention as well as other copper-nickel-silicon alloys includes the sequential steps of (a). casting the copper alloy; (b). hot working the cast copper-base alloy to effect a first reduction in cross-sectional area; (c). solutionizing the cast copper-base alloy at a temperature and for a time effective to substantially form a single phase alloy; (d). first age annealing the alloy at a temperature and for a time effective to precipitate an amount of a second phase effective to form a multi-phase alloy having silicides; (e). cold working the multi-phase alloy to effect a second reduction in cross-sectional area; and (f). second age annealing the multiphase alloy at a temperature and for a time effective to precipitate additional silicides thereby raising conductivity, wherein the second age annealing temperature is less than the first age annealing temperature.