Installation of filter capacitors into feedthroughs for implantable medical devices

• US 6,490,148 B1
• Filed: 01/02/2002
• Issued: 12/03/2002
• Est. Priority Date: 01/02/2002
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch-Hittman, Inc. (Integer Holdings Corporation Inc)
• Inventors: Gelb, Allan S., Allen, Kevin M., Shipman, Thomas W.
• Primary Examiner(s): Dinkins, Anthony
• Application Number:
  US10/037,840
• Time in Patent Office: 335 Days
• Field of Search: 361/302, 361/306.1, 361/321.2, 174/152.GM, 174/50.61, 607/36, 607/37, 607/9
• US Class Current: 361/302
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49179 by metal fusion bonding
• CPC Class Codes: Y10T 29/49183 of ferrule about conductor and terminal

Abstract

A feedthrough device and brazing process for joining the constituent parts of the feedthrough device, while allowing a lead to pass therethrough in a nonconductive manner. The feedthrough comprises at least one lead, a ferrule defining a capacitor recess and defining an insulator recess, an insulator disposed in the insulator recess of the ferrule, the insulator defining a passageway sized to allow the lead to pass therethrough. The feedthrough further comprises a capacitor disposed in the capacitor recess and defining a capacitor passageway sized to allow the lead to pass threrethrough, and the capacitor comprises first and second sets of plates, wherein the first set of plates is conductively coupled to the ferrule and the second set of plates is conductively coupled to the lead. Brazing is a two step process wherein the braze joints between the insulator and the lead and between the insulator and ferrule are formed first at a first temperature using an insulator braze material. The second step of brazing is performed at a lower temperature than the brazing in the first step, and utilizes capacitor braze materials that are different from the insulator braze materials in that they have lower melting temperatures than the insulator braze materials.

Claims

1. A feedthrough comprising:

a lead;

a ferrule defining a capacitor receiving recess and the ferrule also defining an insulator receiving recess;

a capacitor disposed in the capacitor receiving recess, the capacitor defining a capacitor passageway for the lead to pass;

an insulator disposed in the insulator receiving recess, the insulator defining an insulator passageway for the lead to pass through;

an insulator braze material for forming an insulator-ferrule braze joint and for forming an insulator-lead braze joint; and

a capacitor braze material for forming a capacitor-ferrule braze joint and for forming a capacitor-lead braze joint, wherein the insulator braze material is different than the capacitor braze material wherein and the insulator-ferrule braze joint and the insulator-lead braze joint are brazed before the capacitor-ferrule braze joint the capacitor-lead braze joint are brazed.

2. The feedthrough of claim 1 wherein the capacitor comprises a first set of plates and comprises a second set of plates, and wherein the first set of plates is conductively coupled to the ferrule by the capacitor braze material and the second set of plates is conductively coupled to the lead by way of the capacitor braze material, the first set of plates and the second set of plates for filtering electromagnetic interference, and wherein the capacitor braze material is selected from the group consisting of:

seventy-two percent silver and twenty-eight percent copper;

copper and silver and one of the following elements selected from the group consisting of;

titanium, indium, gallium, palladium, platinum, nickel, and tin;

silver-germanium alloys;

gold alloys;

silver-palladium-gallium alloys; and

copper and silver alloys comprising at least one of the elements selected from the group consisting of titanium, indium, gallium, palladium, platinum, nickel and tin.

3. The feedthrough of claim 1 wherein the capacitor braze material used for the capacitor-ferrule braze joint and for the capacitor-lead braze joint comprises seventy-two percent silver and twenty-eight percent copper.

4. The feedthrough of claim 1 wherein the capacitor braze material used for the capacitor-ferrule braze joint and for the capacitor-lead braze joint comprises copper and silver one of the following elements selected from the group consisting of:

titanium, indium, gallium, palladium, platinum, nickel, and tin.

5. The feedthrough of claim 1 wherein the capacitor braze material for the capacitor-ferrule braze joint and the capacitor-lead braze joint is selected from the group consisting of:

silver-germanium alloys;

gold alloys;

silver-palladium-gallium alloys; and

copper and silver alloys comprising at least one of the elements selected from the group consisting of titanium, indium, gallium, palladium, platinum, nickel and tin.

6. The feedthrough of claim 1 wherein the insulator braze material for the insulator-ferrule braze joint and the insulator-lead braze joint comprises gold.

7. The feedthrough of claim 1 wherein the insulator braze material for the insulator-ferrule braze joint and the insulator lead braze joint is selected from the group consisting of:

gold alloys comprising at least one of the following selected from the group consisting of;

tin, copper, silver, palladium, indium, titanium, niobium, vanadium, nickel, molybdenum, platinum;

silver;

silver alloys comprising at least one of the following selected from the group consisting of;

gallium, palladium, and aluminum;

copper silver alloys; and

copper silver alloys comprising at least one of the following selected from the group consisting of;

tin, indium, palladium, nickel, gallium, palladium, and titanium.

8. The feedthrough of claim 2 wherein the ferrule further comprises an interior sidewall for defining the capacitor receiving recess, and the capacitor comprises an exterior capacitor surface provided with a metallized external surface layer, and the capacitor further comprises an internal surface about the capacitor passageway provided with a metallized internal surface layer, and wherein the capacitor braze material upon melting flows between the interior sidewall of the ferrule and the metallized external surface layer of the capacitor and flows between the metallized internal surface layer of the capacitor passageway and the lead.

9. The feedthrough of claim 8 further comprising a thread-type preform comprising capacitor braze material that is wrapped about the lead so that during brazing the thread type preform melts and flows between the lead and the metallized internal surface layer of the capacitor passageway, and the external surface of the capacitor has positioned proximate thereto an annular shaped capacitor preform of capacitor braze material so that during brazing the annular shaped capacitor braze preform melts flows between the interior sidewall of the ferrule and the metallized external surface layer of the capacitor passageway and the lead.

10. The feedthrough of claim 1 wherein the insulator-ferrule braze joint and the insulator-lead braze joint is brazed at first temperature and the capacitor-ferrule braze joint and capacitor-lead braze is braze at a second temperature, the second temperature being less than the first temperature.

11. The feedthrough of claim 10 wherein a thread-type preform wrapped around the lead prior to brazing and the annular shaped capacitor preform for positioning proximate to the exterior capacitor surface comprise seventy-two percent silver and twenty-eight percent copper.

12. The feedthrough of claim 1 wherein the insulator is positioned in the insulator receiving recess and the capacitor is positioned in the capacitor receiving recess such that they contact one another and the lead passes through the ferrule in a nonconductive manner.

13. The feedthough of claim 12 wherein the ferrule is joined to an implantable medical device comprising a housing having an interior, such that the lead passes from the interior of the housing to a location external to the housing by way of the feedthrough in a nonconductive manner.

14. A feedthrough comprising;

a lead

a ferrule defining an insulator receiving recess and an insulator disposed in the insulator receiving recess, the insulator defining a passageway for the lead to pass therethrough, the insulator brazed to the ferrule brazed to the lead with an insulator braze material,

the ferrule further defining a capacitor receiving recess into which a capacitor is disposed, the capacitor comprising capacitor exterior surface and defining a capacitor passageway for the lead to pass therethrough, and

a thread-type preform threaded about the lead at the location where the lead is proximate the capacitor passageway, and an annular capacitor preform positioned adjacent to the capacitor exterior surface, wherein the thread-type preform and the capacitor preform are made of a capacitor braze material and wherein the insulator braze material has a higher melting temperature than the capacitor braze material.

15. The feedthrough of claim 14 wherein the capacitor braze material from which the thread-type preform and the annular capacitor preform are made comprising seventy-two percent silver and twenty-eight percent copper.

16. The feedthrough of claim 14 wherein the thread-type preform and the annular capacitor preform are made from a capacitor braze material comprising copper and silver at least one of the following materials selected from the group consisting of:

titanium, indium, gallium, palladium, platinum, nickel, and tin.

17. The feedthrough of claim 14 wherein the thread-type preform and the capacitor preform are made from a capacitor braze material selected from the group consisting of:

silver-germanium alloys, gold alloys, and silver-palladium-gallium alloys.

18. The feedthrough of claim 14 where the capacitor braze material is selected from the group consisting of:

seventy-two percent silver and twenty-eight percent copper;

copper and silver and at least one of the following selected from the group;

titanium, indium, gallium, palladium, platinum, nickel, and tin; and

silver-germanium alloys, gold alloys, and silver-palladium-gallium alloys.

19. The feedthrough of claim 14 wherein the insulator and the ferrule form an insulator-ferrule braze joint and the insulator and the lead form an insulator-lead braze joint, and the capacitor and the ferrule form a capacitor-ferrule braze joint and the capacitor and the lead form a capacitor-lead braze joint, and wherein the insulator braze material is used for brazing the insulator-ferrule braze joint and the insulator-lead braze joint has a higher melting temperature than the capacitor braze material used for forming the capacitor-ferrule braze joint and the capacitor-lead braze joint, the insulator-ferrule braze joint and the insulator-lead braze joint are formed before the capacitor-ferrule braze joint and the capacitor-lead braze joint are formed.

20. A feedthrough comprising:

a plurality of leads;

a ferrule defining a capacitor receiving recess and the ferrule also defining an insulator receiving recess;

a capacitor disposed in the capacitor receiving recess, the capacitor defining a plurality of capacitor passageway for the plurality of leads to pass;

an insulator disposed in the insulator receiving recess, the insulator defining a plurality of insulator passageways for the lead to pass through;

an insulator braze material for forming an insulator-ferrule braze joint and for forming an insulator-lead braze joint; and

a capacitor braze material for forming a capacitor-ferrule braze joint and for forming a capacitor-lead braze joint, wherein the insulator braze material is different than the capacitor braze material wherein and the insulator-ferrule braze joint and the insulator-lead braze joint are brazed before the capacitor-ferrule braze joint the capacitor-lead braze joint are brazed.