Tin-plated copper-alloy material for terminal and method for producing the same

A tin-plated copper-alloy material for terminal comprising:

• a substrate made of Cu or Cu alloy;
• an Sn-based surface layer formed on a surface of the substrate;
• and
• a Cu—Ni—Sn alloy layer including Ni formed between the Sn-based surface layer and the substrate, wherein
• the Cu—Ni—Sn alloy layer is made of:
• fine Cu—Ni—Sn alloy particles containing Ni not less than 10 at % and not more than 40 at % in a state of column crystal having a cross-sectional diameter of not less than 0.1 μm and not more than 0.8 μm and an aspect ratio of not less than 1.5;
• and coarse Cu—Ni—Sn alloy particles having a cross-sectional diameter more than 0.8 μm,
• an average thickness of the Sn-based surface layer is not less than 0.2 μm and not more than 0.6 μm,
• an area ratio of the Cu—Ni—Sn alloy layer exposed at a surface of the Sn-based surface layer is not less than 10% and not more than 40%, and
• a coefficient of kinetic friction of the tin-plated copper-alloy material for terminal is not more than 0.3.