Patent ID: 8378212

Claim:
An electrical feed-through assembly, comprising: a header having first and second opposing surfaces and having one or more sealed feed-through conductors passing through the header at least from the first surface to the second surface; a housing coupled to the header; and a cured epoxy having solid glass beads mixed therein and disposed between the header and the housing, wherein the glass beads have a diameter and a concentration selected to result in the cured epoxy remaining within a predetermined range of thicknesses of the cured epoxy when the electrical feed-through assembly is exposed to a high pressure liquid from outside of the electrical feed-through assembly, the selection made so that the high pressure liquid will not pass through the epoxy, wherein the concentration of the glass beads is about four percent by weight, wherein the glass beads have diameters in the range of about five to seven mils, and wherein the header comprises: a non-conductive coating disposed on at least the first surface of the header, wherein the non-conductive coating comprises: a metal matching layer comprised of a material selected to bond to the material of the header; a ceramic layer of non-conducting ceramic disposed on the metal matching layer; and an epoxy substantially impregnating pores of the ceramic layer, wherein the epoxy is operable to eliminate a leak path through the ceramic layer when the electrical feed-through assembly is exposed to the high pressure liquid.