Abstract: A bumped substrate assembly comprising an alumina substrate a layer of copper on the alumina substrate, and a heterogeneous juncture band between the alumina the copper layer. Copper bumps integrally connected to the copper layer extend therefrom; the copper in the copper layer and the copper bumps is substantially identical. The heterogeneous juncture band has a copper-wetted surface area that is at least about twice the apparent surface area of the copper overlying the first juncture band and consisting essentially of alumina grains unitary with the copper layer and being constituted by finger-like copper protuberances unitary with the copper layer and occupying the space between the alumina grains.

Abstract: A process for preparing an insulated metallized substrate, wherein a specified metallized substrate is heated from ambient temperature to a peak temperature of at least about 800 degrees centigrade while contacting the substrate with an inert atmosphere containing less than 10 parts per million of oxygen, maintained at such peak temperature for a specified period of time while being contacted with said inert gas, and thereafter heated at a peak temperature of at least about 800 degrees centigrade while being contacted with a gas containing at least 100 parts per million of oxygen.