Ceramic-metal feedthrough lead assembly and method for making same

A feedthrough lead assembly comprising:

• a disk of ceramic material having a lead conducted therethrough and having a surface;
• a metallization layer disposed on a portion of said surface of said ceramic disk;
• a flange ring consisting of metal diffusible into solder and having a projection abutting said surface of said ceramic disk, said flange ring having a surface extending parallel to said surface of said ceramic disk and spaced therefrom at a distance defined by said projection thereby forming a gap between said surfaces;
• and
• a solder connection bridging said gap between said surfaces, said gap having a width such that a diffusion path of the metal of said flange ring into said solder connection is substantially less than the width of said gap, said solder connection having a zone of pure solder between a termination of said diffusion path within said solder connection and said metallization layer on said surface of said ceramic disk.

A method for manufacturing a feedthrough lead assembly comprising the steps of:

• conducting a lead through a ceramic component, said ceramic component having a surface;
• spacing a surface of a flange ring consisting of metal diffusible into solder at a distance from said surface of said ceramic component;
• placing solid solder material between said surfaces of said flange ring and said ceramic component;
• heating said flange ring, said solid solder and said ceramic component in a vacuum to the melting temperature of said solder thereby forming a solder bridge between said surface of said flange ring and said surface of said ceramic component;
• and
• maintaining at least said solder at said melting temperature for a time period such that a diffusion path of said metal of said flange ring into said solder bridge arises which is substantially less than the distance between said surface of said flange ring and said surface of said ceramic component thereby generating a zone of pure solder in said solder bridge in contact with said ceramic component.