Abstract: A method for fabricating metallurgical contacts is disclosed for making thermocompression bonds to a metallized ceramic substrate on which semiconductor chips are to be mounted and electrically contacted. The method comprises placing a nickel layer on the metallized portion of the substrate and then covering the nickel with an immersion layer of gold. The gold immersion layer is selectively removed from locations where thermocompression-bonded contacts are desired. Removal is accomplished by applying a chemical stripper. Heavy gold is electroplated on said locations and the assemblage is heat treated prior to placement of the thermocompression-bonded contacts.

Abstract: A re-work method for removing extraneous plated metal layer areas from the surface of a ceramic substrate containing refractory metal areas wherein the substrate is heated at a temperature for a time sufficient to strengthen the bond between the plated metal layer and the refractory metal areas while simultaneously reducing the strength of the bond between the extraneous plated metal layer overlying the ceramic and the ceramic, immersing the substrate in a liquid, and applying localized ultrasonic energy in close proximity to the extraneous metal areas to be removed.