Abstract: A contact terminal structure includes: a first plating layer formed on a surface of a substrate; and a second plating layer formed on a surface of the first plating layer as an outermost layer, in which the first plating layer is composed of a silver-tin alloy, the second plating layer is silver plating or an alloy essentially consisting of silver, the first plating layer has a hardness greater than the second plating layer, and the first plating layer has a Vickers hardness of 250 to 400 and the second plating layer has a Vickers hardness of 80 to 200.

Abstract: There is provided a plating structure obtained by heat-treating a silver-plated structure obtained by forming a tin-plated layer, an indium-plated layer, or a zinc-plated layer, having a thickness of 0.001 to 0.1 ?m, on a surface of the silver-plated layer formed on a surface of a plating base. There is also provided a coating method for obtaining the plating structure which comprises the step of melting a particle deposit spottedly deposited at 2×10?6 to 8×10?6 g/cm2 such that the spot-deposited particles have gaps therebetween as viewed above and the particles each having an average diameter of 20 to 80 nm do not pile up in a direction perpendicular to the surface of the silver layer to obtain a film.