Abstract: The invention provides Cu—Ni—Si—Co alloys having excellent strength, electrical conductivity, and press-punching properties. In one aspect, the invention is a copper alloy for electronic materials, containing 1.0 to 2.5 mass % of Ni, 0.5 to 2.5 mass % of Co, and 0.30 to 1.2 mass % of Si, the balance being Cu and unavoidable impurities, wherein the copper alloy for electronic material has a [Ni+Co+Si] content in which the median value ? (mass %) satisfies the formula 20 (mass %)???60 (mass %), the standard deviation ? (Ni+Co+Si) satisfies the formula ? (Ni+Co+Si)?30 (mass %), and the surface area ratio S (%) satisfies the formula 1%?S?10%, in relation to the compositional variation and the surface area ratio of second-phase particles size of 0.1 ?m or greater and 1 ?m or less when observed in a cross section parallel to a rolling direction.

Abstract: A Cu—Zn alloy strip and Sn plating strip thereof having improved thermal peel resistance of Sn Plating is provided. In a Cu—Zn alloy strip comprising 15 to 40% by mass of Zn and a balance of Cu and unavoidable impurities, the total concentration of P, As, Sb and Bi is regulated to 100 ppm by mass or less, the total concentration of Ca and Mg is regulated to 100 ppm by mass or less, and the concentrations of O and S are each regulated to 30 ppm by mass or less.