COPPER ALLOY TINNED STRIP HAVING SOLDER WETTABILITY AND INSERTION/EXTRACTION PERFORMANCE

摘要

PROBLEM TO BE SOLVED: To provide a tinned strip suitable as a conductive spring material, having excellent solder wettability and insertion/extraction performance.;SOLUTION: The copper alloy tinned strip is formed by applying base electroplating, Sn electroplating and finally Cu plating in this order on the surface of a copper alloy strip and after that, applying a reflow treatment, wherein a Cu-Sn alloy phase is formed under the Sn plating phase by the reflow treatment. The average value (h) of the difference of the height between the top part of a mountain higher than the average line for the roughness curve and the outermost surface of the Sn plating direct above the top part of the mountain in the boundary between the Sn phase and the Cu-Sn alloy phase in the vertical cross section of the plating surface is 0.1-0.3 μm and the number of pin holes having ≤5.0 μm longest diameter and 0.1-0.4 μm depth in the plating surface is at most 20 per 500 μm×500 μm, the average height Rc of roughness curve element of the Cu-Sn alloy phase surface is preferably ≤0.27 μm and the average length Rsm of the roughness curve element is ≥4.0 μm.;COPYRIGHT: (C)2010,JPO&INPIT