Method for providing a hermetically sealed feedthrough with co-fired filled via for an active implantable medical device

A method for making a hermetically sealed feedthrough, the method comprising the steps of:

• a) providing an alumina substrate, comprising the steps of:
• i) forming a green-state alumina substrate with at least one via hole having a via hole volume;
• ii) filling at least 90% of the via hole volume with a platinum-containing paste, the platinum-containing paste comprising at least 80% platinum particles mixed with at least one solvent and at least one binder;
• and
• iii) heating the green-state alumina substrate and the platinum-containing paste in the via hole to sinter the alumina substrate and bake-out the solvent and the binder from the paste to thereby provide a platinum material in the via hole of the sintered alumina substrate, wherein, after sintering, a shrinkage of the alumina substrate is up to 20% greater than a shrinkage of the platinum material in the via hole;
• b) providing a ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an active implantable medical device (AIMD);
• c) positioning the alumina substrate from step a) in the ferrule opening;
• and
• d) hermetically sealing the alumina substrate to the ferrule, wherein when the ferrule is attached to the opening in the housing of an AIMD, the platinum material in the alumina substrate via hole provides a conductive pathway extending from an alumina substrate body fluid side to an alumina substrate device side, the alumina substrate body fluid and device sides residing outside and inside the AIMD housing, respectively.