Patent ID: 7648601

Claim:
A method for producing a high-strength, high-conductivity copper alloy wire that is excellent in resistance to stress relaxation, comprising the following steps in the following order: rough drawing a copper alloy comprising 1.0 to 4.5% by mass of Ni, 0.2 to 1.1% by mass of Si, 0.05 to 1.5% by mass of Sn, and less than 0.005% (including zero) by mass of S, optionally 0.2 to 1.5% by mass of Zn, and optionally one or plural elements selected from the group consisting of 0.005 to 0.3% by mass of Ag, 0.01 to 0.5% by mass of Mn, 0.01 to 0.2% by mass of Mg, 0.005 to 0.2% by mass of Fe, 0.005 to 0.2% by mass of Cr, 0.05 to 2% by mass of Co, and 0.005 to 0.1% by mass of P in a total amount of 0.005 to 2% by mass, with the balance being Cu and inevitable impurities, to form a wire rod; subjecting the wire rod to a solution treatment; intermediate drawing at a reduction ratio of 3 or more; aging at from 400° C. to 600° C. for 1.5 hours or more; and final drawing at a reduction ratio of from 0 to less than 3, thereby obtaining a copper alloy wire having a conductivity of 40% IACS or more and a tensile strength of 700 MPa or more.