Method of making hermetic feedthrough in ceramic substrate

A process for forming an hermetic feedthrough in a ceramic substrate which comprises providing a sheet of a liquid phase sinterable ceramic composition having a feedthrough hole, at least substantially filling said feedthrough hole with a refractory metal metallization-forming material, firing the resulting structure to produce a sintered structure comprised of a sintered ceramic substrate having an hermetic electrically conductive refractory metal metallization, said ceramic substrate containing at least about 1% by volume of glassy phase, said metallization being comprised of an intermixture of a continuous phase of refractory metal and a continuous phase of glass, said refractory metal ranging from about 25% by volume to about 75% by volume of said metallization, said liquid phase ceramic composition and said metallization-forming material being formulated to produce said sintered structure, contacting said refractory metal at at least one exposed portion of said metallization with an intrusion metal selected from the group consisting of copper, nickel, tin, gold, iron, cobalt, and an alloy thereof, heating the resulting structure to an infiltration temperature which is above the transition temperature of said glass and at which said intrusion metal is liquid but said refractory metal is solid thereby infiltrating said liquid intrusion metal into said metallization, at said infiltration temperature said liquid metal preferentially wetting said refractory metal displacing said glass with said intrusion metal, and allowing the resulting structure to cool thereby solidifying said infiltrated liquid intrusion metal in place producing said feedthrough, said solid infiltrated intrusion metal at least partly occupying the volume space originally occupied by said displaced glass and being in contact with said refractory metal phase, said solid intrusion metal comprising at least about 25% by volume of said feedthrough, said process being carried out in an atmosphere which has no significant deleterious effect on said ceramic substrate, said refractory metal metallization and said intrusion metal.

A process for forming an hermetic feedthrough in a ceramic substrate which comprises providing a sintered structure comprised of a sintered ceramic substrate having an electrically conductive refractory metal metallization in a feedthrough hole therein, said ceramic substrate containing at least about 1% by volume of glassy phase, said metallization being comprised of a continuous phase of refractory metal and a continuous phase of glass, said refractory metal ranging from about 25% by volume to about 75% by volume of said metallization, said ceramic substrate and said metallization being formulated to produce said sintered structure, contacting said refractory metal at at least one exposed portion of said metallization with an intrusion metal selected from the group consisting of copper, nickel, tin, gold, iron, cobalt, and an alloy thereof, heating the resulting structure to an infiltration temperature which is above the transition temperature of said glass and at which said intrusion metal is liquid but said refractory metal is solid thereby infiltrating said liquid intrusion metal into said metallization, at said infiltration temperature said liquid metal preferentially wetting said refractory metal displacing said glass with said intrusion metal, and allowing the resulting structure to cool thereby solidifying said infiltrated liquid intrusion metal in place producing said feedthrough, said solid infiltrated intrusion metal at least partly occupying the volume space originally occupied by said displaced glass and being in contact with said refractory metal phase, said solid intrusion metal comprising at least about 25% by volume of said feedthrough, said process being carried out in an atmosphere which has no significant deleterious effect on said ceramic substrate, said refractory metal metallization and said intrusion metal.