Patent ID: 7172662

Claim:
A copper alloy material for parts of electronic and electric machinery and tools, consisting of 1.0 to 3.0% by mass of Ni, 0.2 to 0.7% by mass of Si, 0.01 to 0.2% by mass of Mg, 0.05 to 1.5% by mass of Sn, 0.2 to 1.5% by mass of Zn, less than 0.005% by mass (including 0% by mass) of S, and optionally 0.01 to 0.5% by mass in a total amount of at least one selected from the group consisting of Fe, Zr, P, Mn, Ti, V, Pb, Bi and Al, with the balance being Cu and inevitable impurities, wherein a crystal grain diameter is more than 0.001 mm and 0.025 mm or less; the ratio (a/b), between a longer diameter a of a crystal grain on a cross section parallel to a direction of final plastic working, and a longer diameter b of a crystal grain on a cross section perpendicular to the direction of final plastic working, is 1.5 or less; and wherein a surface roughness Ra after the final plastic working is more than 0 Î¼m and less than 0.1 Î¼m, or a surface roughness Rmax is more than 0 Î¼m and less than 2.0 Î¼m, and wherein the material is excellent in bending property and stress relaxation property.