Installation of filter capacitors into feedthroughs for implantable medical devices

Abstract

A feedthrough device and brazing process for joining the constituent parts of the feedthrough device, while allowing a lead to pass therethrough in a nonconductive manner. The feedthrough comprises at least one lead, a ferrule defining a capacitor recess and defining an insulator recess, an insulator disposed in the insulator recess of the ferrule, the insulator defining a passageway sized to allow the lead to pass therethrough. The feedthrough further comprises a capacitor disposed in the capacitor recess and defining a capacitor passageway sized to allow the lead to pass threrethrough, and the capacitor comprises first and second sets of plates, wherein the first set of plates is conductively coupled to the ferrule and the second set of plates is conductively coupled to the lead. Brazing is a two step process wherein the braze joints between the insulator and the lead and between the insulator and ferrule are formed first at a first temperature using an insulator braze material. The second step of brazing is performed at a lower temperature than the brazing in the first step, and utilizes capacitor braze materials that are different from the insulator braze materials in that they have lower melting temperatures than the insulator braze materials.