CONDUCTIVE MATERIAL FOR CONNECTING PART AND METHOD FOR MANUFACTURING THE CONDUCTIVE MATERIAL

摘要

There is provided a conductive material comprising a base material made up of a Cu strip, a Cu-Sn alloy covering layer formed over a surface of the base material, containing Cu in a range of 20 to 70 at.%, and having an average thickness in a range of 0.1 to 3.0 µm, and an Sn covering layer formed over the Cu-Sn alloy covering layer having an average thickness in a range of 0.2 to 5.0 µm, disposed in that order, such that portions of the Cu-Sn alloy covering layer are exposed the surface of the Sn covering layer, and a ratio of an exposed area of the Cu-Sn alloy covering layer to the surface of the Sn covering layer is in a range of 3 to 75%. The surface of the conductive material is subjected to a reflow process, and preferably, an arithmetic mean roughness Ra of the surface of the material, in at least one direction, is not less than 0.15 µm while the arithmetic mean roughness Ra thereof, in all directions, is not more than 3.0 µm, and the average thickness of the Cu-Sn alloy covering layer is preferably not less than 0.2 µm. The conductive material is fabricated by a method whereby the surface of the base material is subjected to roughening treatment, an Ni plating layer, a Cu plating layer, and an Sn plating layer are formed, as necessary, over the surface of the base material, and subsequently, a reflow process is applied.