Abstract: A ceramic substrate is provided with filled via holes for electrical or thermal feedthrough to or from an electronic device, each via hole having at least one dimension from about 4 to about 50 mils. The via holes are filled with copper, silver or gold for high conductivity and the filling is without visible voids at a magnification of 1000 diameters. The filling is preferably hermetic and is achieved by first electrodepositing metal into the holes and extending therefrom as dumbbell shaped plugs and then heating the substrate to the melting point of the metal so that metal from the dumbbell ends enters the connecting portion within the via hole to seal any aperture therein.

Abstract: A ceramic substrate is provided with filled via holes for electrical or thermal feedthrough to or from an electronic device, each via hole having at least one dimension from about 4 to about 50 mils. The via holes are filled with copper, silver or gold for high conductivity and the filling is without visible voids at a magnification of 1000 diameters. The filling is preferably hermetic and is achieved by first electrodepositing metal into the holes and extending therefrom as dumbbell shaped plugs and then heating the substrate to the melting point of the metal so that metal from the dumbbell ends enters the connecting portion within the via hole to seal any aperture therein.

Abstract: For use as a substrate for a heat generating microelectronic integrated circuit, a ceramic panel is provided having small thickness in comparison to its length and breadth, having on at least the surface opposite the one bearing the microelectronic integrated circuit, a layer of heat conductive metal and having a plurality of closely spaced, small cross section extensions of the heat conductive metal layer extending into the ceramic material to a depth of at least about one fifth of its thickness. The substrate is particularly useful for the mounting of hybrid microelectronic circuits to improve the heat dissipation capability of the ceramic substrate.