Abstract: A method of forming a microwave integrated circuit is disclosed. A hole is bored in an alumina substrate and a plug having a diameter substantially equal to the hole is provided. The hole and the perimeter of the plug are coated with a thermally fusable dielectric composition and the plug is embedded in the hole. Heating the substrate fuses the plug is place and crystalizes the composition into a glass with compatible thermal expansion. At least one face of the substrate and plug are then polished to provide a planar surface. The metalized circuit is then formed on this assembly, which minimizes conductive tracking on the substrate and facilitates alignment of the circuit with the plug.

Abstract: A microwave integrated circuit is comprised of a ferrite plug in an alumina substrate, fused therein by a glass composition thermally compatible with both plug and substrate, thereby filling any voids at the interface with dielectic material to minimize circuit losses. The method of assembly permits metalizing the substrate after insertion of the plug, minimizing conductive tracking on the substrate, and facilitating alignment of the metalized circuit with the plug.