| abstract |
The present invention relates to a Sn plating material having Sn plating on a surface of a substrate made of copper or a copper alloy, wherein a base layer composed of at least one of Ni and a Cu-Ni alloy is formed on a surface of the substrate, and The outermost layer is formed on the surface of the base layer, and the outermost layer is a Cu-Sn-based alloy layer composed of crystal grains of a plurality of Cu-Sn-based alloys, and a Cu-Sn-based alloy adjacent to the outermost surface. The Sn layer in the concave portion between the crystal grains is formed; the area ratio of the Sn layer in the outermost surface is 20 to 80%, and the maximum thickness of the Sn layer is smaller than the average grain size of the Cu-Sn-based alloy. |