Abstract: Dense vias may be made with a metallizing composition containing tungsten, alumina, and either nickel or palladium. Further, an infiltration process ensures that vias in ceramic substrates are heremetic. Infiltrating materials, including metals and alloys, are applied to co-fired substrates and the composite is fired. The process may be repeated if necessary. Alternatively, the via holes may be bore-coated prior to infiltrating.

Abstract: A tungsten paste suitable for co-sintering with 98+% alumina substrate can be produced by adding selected compositions of glass to the paste. Circuit packages produced in accordance with the present invention exhibit superior thermal conductivity, low shrinkage variability, and smoother and more homogeneous surface finish. A preferred embodiment of the invention utilizes a substrate comprising narrow size range alumina powder, thus yielding lower sintering temperature and further improvements in shrinkage variability and surface finish.

Abstract: Suspensions of ceramic or metallic colloidal particles having a high volume fraction (greater than about 55 vol. %) solid particles are provided in a pourable form. The pourable suspension includes at least about 55 vol. % ceramic or metallic colloidal particles, an aqueous vehicle, and an acrylic acid-based polymeric polyelectrolytic dispersant. Such suspensions can be prepared by mixing the colloidal particles in a staged order of addition and under a high shear rate with the other components. The suspensions are suitable for making ceramic or metallic articles, and can exhibit a low viscosity.

Abstract: This invention relates to glass-ceramic packages for integrated circuits containing multi-layer, interconnected thick film wiring patterns obtained by co-sintering a glass-ceramic composite and copper, silver, palladium or gold based conductors at temperatures not exceeding about 1000.degree. C. The dielectric systems disclosed herein contains composites of borosilicate glasses and crystalline fillers which are fabricated by either mixing glass frit and the filler or by a sol-gel coating process.

Abstract: Commercial wide size distribution powders are size classified into precise size fractions by means of a controlled, semi-continuous, multi-stage centrifugal classification system. The system has utility for a wide range of colloidal materials. The throughput of the semi-continuous process is higher than that of batch processes, and the semi-continuous process produces narrow size ranges and optimum yields.

Abstract: Substrates consisting of at least 98% narrow size distribution ceramic particles are co-sinterable with metallized paste to which selected compositions of glass have been added. Substrates produced in accordance with the present invention exhibit superior thermal conductivity, low shrinkage variability, and smoother and more homogeneous surface finish.