Hermetically sealed microstrip to microstrip transition for printed circuit fabrication

The transition interconnects microstrip transmission lines whose finite-width conductors are formed on the upper surface and whose ground planes are formed on the under surface of a ceramic substrate. A patternable metallizable multilayer thick film dielectric is applied to the under surface of the ceramic substrate. The transition comprises first and second vias which penetrate the ceramic substrate inside and outside a hermetic enclosure. The upper ends of the vias are connected to the finite-width transmission line conductors, and the lower ends of the vias are interconnected by a finite-width conductor formed on the under surface of the substrate. The lower conductor then forms a transmission line of either a microstrip or coplanar nature with a ground plane available on the underside of the assembly. The thick film dielectric facilitates sealing, and attachment of a metal base plate. All steps are performed using thick film processing.