Electronics package suitable for implantation
The invention is directed to a method of bonding a hermetically sealed electronics package to an electrode or a flexible circuit and the resulting electronics package that is suitable for implantation in living tissue, such as for a retinal or cortical electrode array to enable restoration of sight to certain non-sighted individuals. The hermetically sealed electronics package is directly bonded to the flex circuit or electrode by applying conductive adhesive between electrical contacts and non-conductive underfill around the contacts. The resulting electronic device is biocompatible and is suitable for long-term implantation in living tissue.
1. An implantable electronic device, comprising:
a) a hermetic implantable package including electronics;
b) a substrate forming part of said hermetic implantable package and having one or more contacts and two or more layers of conductive adhesive on said contacts, and said substrate forming part of a hermetic package surrounding said electronic device;
c) a flexible assembly having one or more bond pads and one or more layers of conductive adhesive on said bond pads;
d) said conductive adhesive connecting said contacts on said substrate with said bond pads on said flexible assembly; and
e) adhesive underfill in the remaining space between said substrate and said flexible assembly.
2. The device according to claim 1 wherein said flexible assembly comprises polyimide.
3. The device according to claim 1 wherein said substrate comprises a biocompatible ceramic.
4. The device according to claim 1 wherein said biocompatible ceramic comprises alumina.
5. The device according to claim 1 wherein said substrate is rigid.
6. The device according to claim 1 wherein said substrate is an electrically insulated substrate circuit.
7. The device according to claim 1 wherein said flexible assembly is a thin substrate circuit.
8. The method according to claim 1 wherein said conductive adhesive provides an electrical path between said input/output contacts and said bond pads.
9. The method according to claim 1 wherein said adhesive underfill is nonconductive.
10. The method according to claim 1 wherein said adhesive underfill contains epoxy.