Package for an implantable neural stimulation device
The present invention is an improved hermetic package for implantation in the human body. The implantable device includes an electrically non-conductive substrate with electrically conductive vias. A flip-chip circuit is attached to the substrate using conductive bumps and electrically connected to a first subset of the vias. The flip-chip circuit can contain one or more stacks or a folded stack. A wire-bonded circuit is also attached to the substrate and electrically connected to a second subset of the vias. A cover is bonded to the substrate. The cover, substrate, and vias form an improved hermetic package for implantation.
1. An implantable device, comprising:
a rigid substrate having an electrically non-conductive portion;
a plurality of electrically conductive vias through said electrically non-conductive portion, said vias and electrically non-conductive portion forming said rigid substrate;
metal traces on said rigid substrate electrically connected to said conductive vias;
a circuit attached to said metal traces;
a braze stop surrounding said metal traces, the braze stop comprising metal selected from the group including Ti, Zr, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, layers or alloys thereof;
a cover bonded to said rigid substrate with a braze, said cover and said rigid substrate forming a hermetic package;
wherein said braze stop trace prevents said braze from contacting said metal traces.
2. The implantable device according to claim 1 , wherein said electrically conductive vias are a metallic and ceramic paste co-fired with said electrically non-conductive portion to form a hermetic seal.
3. The implantable device according to claim 1 , wherein said metal traces are chosen to withstand braze temperatures.
4. The implantable device according to claim 1 , wherein said metal traces comprise one or more of the metals titanium, tantalum, gold, palladium, platinum or layers or alloys thereof.
5. The implantable device according to claim 1 , further comprising a flexible circuit bump bonded with conductive bumps to said rigid substrate.
6. The implantable device according to claim 1 , further comprising additional metal traces deposited on said rigid substrate and in contact with said electrically conductive vias; and a flexible circuit at bump bonded with conductive bumps to said additional metal traces.
7. The implantable device according to claim 5 , wherein said flexible circuit is an electrode array suitable for stimulating tissue.
8. The implantable device according to claim 5 , wherein said conductive bumps contain at least one conductive polymer.
9. The implantable device according to claim 8 , wherein said conductive bumps contain at least one conductive epoxy or polyimide.
10. The implantable device according to claim 5 , wherein said conductive bumps are filled with one or more metals from the group including silver, platinum, iridium, titanium, platinum alloys, iridium alloys, or titanium alloys or mixtures thereof.
11. The implantable device according to claim 10 , wherein said metals or metal alloys are in dust, flake or powder form.
12. The implantable device according to claim 1 , wherein said implantable device contains two or more integrated circuits.
13. The implantable device according to claim 1 , where said circuit is flip-chip bonded to said metal traces.
14. The implantable device according to claim 1 , wherein said circuit is wire bonded to said metal traces.