Alloy 42 is a 42% Nickel, 58% Iron alloy that is used because it has a coeficient of expansion similar to that of glass, so may be used for lead frames in ceramic packages. Tin/Lead plated Alloy 42 is pretty standard stuff, but it likely should be fused (reflowed) or it will not have a good shelf life. Hope this helps. Rudy Sedlak RD Chemical Company