| abstract |
Maskless technique for plating a protective metal layer on existing metallurgical pattern supported on a dielectric substrate by blanket coating said metal layer over said substrate, heating to diffuse the metal into said pattern, cooling to spall the metal on the non-patterned portions of the substrate surfaces by the stresses induced from the differences in the thermal contraction differentials between the metal and the substrate, and mechanically removing the metal layer from the non-patterned substrate surfaces. Optionally, the metal layer can also be blanket coated with a passivating metal film with interdiffusion between them at their interface during the noted heating step. In application to support carriers for mounting of semiconductor devices, the substrate will comprise an alumina based ceramic, the pattern will comprise a molybdenum based metal, and the protective metal layer can comprise a nickel based metal. In this application, the second passivating metal film can comprise gold. |