Co-fired hermetically sealed feedthrough with alumina substrate and platinum filled via for an active implantable medical device

Patent metadata

Field	Value
Publication number	US-RE47624-E
Application number	US-201615016368-A
Country	US
Kind code	E1
Filing date	Feb 5, 2016
Priority date	Jan 16, 2012
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A co-fired hermetically sealed feedthrough is attachable to an active implantable medical device. The feedthrough comprises an alumina dielectric substrate comprising at least 96 or 99% alumina. A via hole is disposed through the alumina dielectric substrate from a body fluid side to a device side. A substantially closed pore, fritless and substantially pure platinum fill is disposed within the via hole forming a platinum filled via electrically conductive between the body fluid side and the device side. A hermetic seal is between the platinum fill and the alumina dielectric substrate, wherein the hermetic seal comprises a tortuous and mutually conformal interface between the alumina dielectric substrate and the platinum fill.

First claim

What is claimed is:

1. A hermetically sealed feedthrough that is attachable to an active implantable medical device (AIMD), the feedthrough comprising:
a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively;
b) an alumina substrate comprised of at least 96% alumina and having a thickness extending from to a substrate body fluid side and to a substrate device side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule;
b) ac) an active via hole disposedextending through the alumina substrate fromto the substrate body fluid side and to the substrate device side, wherein a counter-bore in the substrate is aligned with the active via hole and has a depth that extends from the substrate body fluid side part-way into the substrate thickness;
c)d) a substantially closed pore and substantially pureclosed-pore platinum fill disposed withinthat is hermetically sealed to the alumina substrate in the active via hole and, the substantially closed-pore platinum extending betweento the counter-bore at the substrate body fluid side and to or adjacent to the substrate device side of the alumina substrate; and
d) a hermetic seal between the platinum fill and the alumina substrate,
e) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion at least partially resides in the counter-bore on the substrate body fluid side with the post extending into the substantially closed-pore platinum in the active via hole, and
f) wherein the platinum fill forms a tortuous and mutually conformal knitline or interface between the alumina substrate and the platinum fill pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and
g) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness.

2. The feedthrough of claim 1 , wherein the alumina substrate comprises at least 99% alumina.

3. The feedthrough of claim 1 , wherein there is a tortuous and mutually conformal knitline between the alumina substrate and the platinum fill and wherein the knitline comprises a glass that is at least about 60% silica.

4. The feedthrough of claim 1 , wherein the hermetic seal has a leak rate at least no greater than 1×10 −7 std cc He/sec.

5. The feedthrough of claim 1 , wherein an inherent shrink rate during a heat treatment of the alumina dielectric substrate in a substrate green state is greater than that of the substantially closed-pore platinum fill in the a platinum green state.

6. The feedthrough of claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been formed from a platinum paste that prior to bake out bake-out and sintering had a platinum metal content of at least 80%.

7. The feedthrough of claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been formed from a platinum paste that prior to bake out bake-out and sintering had a platinum metal content of about 95%.

8. The feedthrough of claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been packed into the active via hole prior to bake out bake-out and sintering to occupy at least 90% of the available space in the active via hole.

9. The feedthrough of claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been packed into the active via hole prior to bake out bake-out and sintering to occupy about 99% of the available space in the active via hole.

10. The feedthrough of claim 1 , wherein, as a result of having been subjected to a bake-out and sintering, the alumina dielectric substrate is characterized as having shrunk from a substrate green state by about 20% to about 14% more than the substantially closed-pore platinum fill shrinks from a platinum green state as a result of having been subjected to bake out and sintering.

11. The feedthrough of claim 1 , wherein, as a result of having been subjected to bake-out and sintering, the alumina dielectric substrate is characterized as having shrunk from a substrate green state by about 16% more than the substantially closed-pore platinum fill shrinks from a platinum green state as a result of having been subjected to bake out and sintering.

12. The feedthrough of claim 1 , wherein a difference in a first coefficient of thermal expansion (CTE) of the alumina dielectric substrate and a second CTE of the substantially closed-pore platinum fill is from about 0.5×10 −6 /K to about 1.0×10 −6 /K.

13. The feedthrough of claim 1 , wherein the platinum filled active via hole comprises a larger cross sectional cross-sectional area at either both a first active via end exposed to at the substrate body fluid side or and at a second active via end exposed to at the substrate device side as compared to a smaller cross sectional cross-sectional area of the platinum filled that portion of the active via hole that resides between the first and second active via ends.

14. The feedthrough of claim 1 including an electrically conductive cap or protrusion co-fired to the platinum fill on the body fluid side.

15. The feedthrough of claim 14 1, wherein the cap or protrusion bond pad comprises platinum or titanium.

16. The feedthrough of claim 1 , including an adhesion metallization disposed on an outside outer circumferential surface of the alumina substrate and a wetting metallization disposed on the adhesion metallization.

17. The feedthrough of claim 16 including a wetting metallization disposed on the adhesion metallization.

18. The feedthrough of claim 17 including a ferrule disposed around the alumina substrate 16, wherein a gold braze hermetically seals the ferrule to the adhesion and wetting metallizations disposed on the alumina substrate.

19. The feedthrough of claim 18 including a gold braze hermetically sealing the alumina substrate to the ferrule.

20. The feedthrough of claim 19 18, wherein the braze between the alumina substrate and the ferrule has a leak rate at least no greater than 1×10 −7 cc He/sec.

21. The feedthrough of claim 20 1, wherein the ferrule comprises titanium.

22. The feedthrough of claim 16 , wherein the adhesion metallization comprises titanium and the wetting metallization comprises niobium or molybdenum.

23. The feedthrough of claim 17 wherein the wetting metallization comprises niobium or molybdenum.

24. The feedthrough of claim 1 , wherein the alumina dielectric substrate comprises a castellation recess disposed on the substrate device side, and wherein a monolithic chip capacitor is disposed within the castellation recess, the monolithic chip capacitor comprising an active electrode plate set disposed parallel to a ground electrode plate set, the active electrode plate set being electrically connected to the substantially closed-pore platinum disposed in the active via hole by a first circuit trace disposed within the alumina substrate, and the ground electrode plate set being electrically connected to an outer metallization disposed on the alumina substrate by a s

Assignees

• Greatbatch Ltd

Inventors

• Tang Xiaohong
• Thiebolt William C
• Frysz Christine A
• Seitz Keith W
• Stevenson Robert A
• Brendel Richard L
• Marzano Thomas
• Woods Jason
• Frustaci Dominck J
• Winn Steven W

Classifications

• A61N1/375

  Constructional arrangements, e.g. casings · CPC title

• A61N1/37512

  Pacemakers · CPC title

• H01G2/103

  Sealings, e.g. for lead-in wires; Covers · CPC title

• H01G4/12

  Ceramic dielectrics {(H01G4/085 takes precedence)} · CPC title

• H01G4/35

  Feed-through capacitors or anti-noise capacitors · CPC title