Importance

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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. Where the core composite includes copper outer surface materials or is plated to have copper outer surface materials, the core and ceramic materials and particularly multiple sections of the ceramic materials are provided in spaced relation on the metal cores of relatively large area and are preferably bonded to the core using a copper oxide eutectic formed on the core surface.

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First Claim