Metallized ceramic substrate and method therefor

An apertured metal-ceramic composite comprising;

• a ceramic workpiece that defines at least one through passageway from one face of the ceramic workpiece to another face thereof;
• a layer of electrically conductive metal on each of said faces and within said through passageway, the layer of electrically conductive metal within said through passageway providing a conductive path from said one face of the ceramic workpiece to the said other face of the workpiece;
• and
• a heterogeneous juncture band between, and substantially coextensive with, said ceramic workpiece, including said through passageway, and said conductive metal layer;
• said heterogeneous juncture band having a metal-wetted surface area that is at least about twice the apparent surface area of the metal layer overlying the juncture band and consisting essentially of ceramic grains unitary with said workpiece and said conductive material, and being constituted by finger-like metal protuberances unitary with the metal layer and occupying the space between the ceramic grains;
• and said metal-ceramic composite being capable of withstanding repeated firing cycles at a temperature in excess of 850.degree. C. without separation of the metal layer from the working surface of the ceramic workpiece.