Sn PLATED MATERIAL AND PRODUCTION METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To provide an Sn plated material which is low in insertion force when used as a material for electrical elements, e.g. connection terminals capable of being inserted/removed and ejection and a method of producing the Sn plated material at low costs.SOLUTION: An Sn plated material is provided with an Sn plating on the surface of a substrate 10 composed of copper or a copper alloy. A ground layer 12 composed of Ni or a Cu-Ni alloy is formed on the surface of the substrate 10, and an outermost layer which consists of a Cu-Sn alloy layer 14 composed of a large number of crystal grains of a Cu-Sn alloy and an Sn layer 16 formed in concave parts among the crystal grains of the adjacent Cu-Sn alloy in the outer most layer is formed on the surface of the ground layer 12. The area ratio of the Sn layer 16 occupying in the outermost surface is 20-80%, and the maximum thickness of the Sn layer 16 is smaller than the average grain particle of the crystal grains of the Cu-Sn alloy.