Abstract: Ceramic to metal stock or substrates having a relatively large and thick metal core and a relatively thin ceramic layer or layers are bonded to the metal core or a selected portion thereof by providing a metal core material having a temperature coefficient of expansion which is tailored to the temperature coefficient of expansion of the ceramic layer to be bonded thereto. The typical core materials include multilayer composite metal laminates embodying Cu/Mo/Cu, Cu/Kovar/Cu, Cu/Invar/Cu and the like and including powdered metal composites embodying Cu-W, Ag-Mo, Ag-W, Al-Si, Cu/Mo/Cu, Cu/Kovar/Cu, SiC-Cu, Ni-Fe alloys having from about 20% Ni to about 80% Ni, etc. The ceramic layer is chosen primarily for the properties of dielectric strength and isolation properties and typically include such ceramics as alumina, beryllium oxide, aluminum nitride, silicon carbide, etc.

Abstract: An improved surface mounted system for leaded semiconductor devices has J-shaped device leads soldered to respective portions of circuit pads on a printed circuit board, each lead having inner and outer surfaces of the J-shape covered with solder dewetting and solder wetting metals respectively which are metallurgically bonded to a metal core of the lead formed of a springy, relatively high electrical conductivity metal.