Package for an implantable neural stimulation device
The present invention is an improved hermetic package for implantation in the human body. The implantable device of the present invention includes an eclectically non-conductive bass including electrically conductive vias through the substrate. A circuit is flip-chip bonded to a subset of the vias. A second circuit is wire bonded to another subset of the vias. Finally, a cover is bonded to the substrate such that the cover, substrate and vias form a hermetic package.
1. A hermetic package for an implantable device, comprising:
an electrically non-conductive substrate having a substantially planar inside surface;
a plurality of electrically conductive vias through said electrically non-conductive substrate, patterned thin film metallization suitable to withstand braze temperatures on the electrically non-conductive substrate, the electrically non-conductive substrate patterned thin film metallization and the electrically conductive vias forming a base;
a flip-chip circuit attached directly to said base using conductive bumps and electrically connected to at least one of said plurality of electrically conductive vias, the flip-chip circuit not suitable to withstand braze temperatures wherein the flip-chip circuit is smaller than the electrically non-conductive substrate defining a wire bonding region between the flip-chip circuit and the edge of the electrically non-conductive substrate;
a wire bonded hybrid stack circuit, including thin film metallization, wire bonded directly to said base in the wire bonding region;
a ring bonded to the substantially planner inside surface of said base; and
a cover bonded to said ring and a lip to engage said cover to said ring, said cover, said lip, said ring and said base forming a hermetic package;
wherein said wire bonded hybrid stack circuit is mounted on said flip chip circuit.
2. The implantable device of claim 1 , wherein said electrically non-conductive substrate contains ceramic.
3. The implantable device according to claim 2 , wherein said cover contains metal.
4. The implantable device according to claim 2 , wherein said electrically conductive vias are a metallic and ceramic paste co-fired with said electrically non-conductive substrate to form a hermetic seal.
5. The implantable device according to claim 2 , wherein said ring is brazed to said electrically non-conductive substrate.
6. The implantable device according to claim 1 , wherein said patterned thin film metallization is multiple layer thin film metallization and said first circuit and said second circuit are bonded to said patterned thin film metallization.
7. The implantable device according to claim 6 , wherein said multiple layer thin film metallization is chosen to withstand braze temperatures.
8. The implantable device according to claim 7 , wherein said multiple layer thin film metallization comprises more than one of the metals titanium, tantalum, gold, palladium, platinum or layers or alloys thereof.
9. The implantable device according to claim 1 , further comprising a flexible circuit bump bonded to said vias.
10. The implantable device according to claim 1 , further comprising
metal traces deposited on said electrically non-conductive substrate and in contact with said electrically conductive vias; and
a flexible circuit attached to said metal traces.
11. The implantable device according to claim 10 , wherein said flexible circuit is an electrode array suitable for stimulating tissue.
12. The implantable device according to claim 1 , further comprising a polymer underfill under said flip-chip circuit.
13. The implantable device according to claim 1 , wherein said conductive bumps contain at least one conductive polymer.
14. The implantable device according to claim 1 , wherein said conductive bumps contain at least one conductive epoxy or polyimide.
15. The implantable device according to claim 1 , wherein said conductive bumps are filled with one or more metals like silver, platinum, iridium, titanium, platinum alloys, iridium alloys, or titanium alloys or mixtures thereof.
16. The implantable device according to claim 15 , wherein said metal or metal alloys are in dust, flake or powder form.
17. The implantable device according to claim 1 , further comprising a getter.
18. The implantable device according to claim 17 , wherein the getter is placed on the inside of a lid.