Reduced capacitance chip carrier

Abstract

A ceramic chip carrier package for integrated circuits is described which provides reduced interlead capacitance. A cavity for the placement of the integrated circuit chip is centrally located on a substrate. The leads of the package are bridged between the cavity and the outer periphery of the substrate. The leads are bonded to the substrate using adhesive glass placed on the substrate at the outer periphery of the cavity and at the outer periphery of the substrate. Sealing glass is placed on the outer periphery of the substrate over the leads to provide a bonding material for a lid to the package. The area between the cavity and the outer periphery of the substrate has no adhesive or sealing glass which thus provides an air dielectric between the leads so that interlead capacitance is reduced. In a second preferred embodiment, a channel is provided in the ceramic substrate between the periphery of the cavity and the periphery of the substrate to control the flow of adhesive glass and sealing glass so that the glasses do not migrate onto the leads. Since the air dielectric constant is lower than the glass dielectric constant, the interlead capacitance is lower than that found in prior art packages.