Abstract: An electrical conductor has a copper base substrate coated with a tin base coating layer. To inhibit the diffusion of copper from the substrate into the coating layer and the consequential formation of a brittle tin/copper intermetallic, a barrier layer is interposed between the substrate and the coating layer. This barrier layer contains from 20% to 40%, by weight, of nickel and is preferably predominantly comprised of copper. In one embodiment, an intermetallic layer selected from the group (Cu--Ni).sub.3 Sn, (Cu--Ni).sub.6 Sn.sub.5, Cu.sub.3 Sn, Cu.sub.6 Sn.sub.5 is disposed between the barrier layer and the tin base coating layer.