Installation of filter capacitors into feedthroughs for implantable medical devices

• US 6,920,673 B2
• Filed: 08/02/2002
• Issued: 07/26/2005
• Est. Priority Date: 01/02/2002
• Status: Expired due to Fees

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch-Hittman, Inc. (Integer Holdings Corporation Inc)
• Inventors: Allen, Kevin M., Shipman, Thomas W., Gelb, Allan S.
• Primary Examiner(s): Trinh, Minh
• Assistant Examiner(s): Nguyen, Donghai D.
• Application Number:
  US10/211,697
• Publication Number:
  US 20030123215A1
• Time in Patent Office: 1,089 Days
• Field of Search: 29/250.3, 29/254.2, 29D/IG.4, 298/32, 298/40, 298/43, 298/60, 298/62, 174/50.61, 174/152.GM, 361/302, 361/306.1, 361/321.3, 607/9, 607/36, 607/37
• US Class Current: 29/25.42
• 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 while allowing a lead to pass therethrough in a nonconductive manner is described. The feedthrough comprises at least one lead, a ferrule defining a capacitor recess and an insulator recess. An insulator disposed in the insulator recess defines a passageway allowing the lead to pass therethrough. A capacitor disposed in the capacitor recess defines a capacitor passageway allowing the lead to pass therethrough. The capacitor comprises first and second sets of plates, the first set being conductively coupled to the ferrule and the second set being conductively coupled to the lead. 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. Next, a capacitor braze material is used to braze the first set of capacitor plates to the lead and the second set of capacitor plates to the ferrule at a lower temperature than the brazing of the insulator braze materials.

Claims

1. A process for brazing a filter capacitor in a feedthrough device, comprising the acts of:

a) providing a ferrule defining a capacitor receiving recess;

b) disposing a capacitor in the capacitor receiving recess;

c) providing the capacitor with a passageway, the capacitor having a metallized external surface and a metallized internal surface about the capacitor passageway;

d) positioning a lead passing through the capacitor passageway;

e) positioning an annular preform of a capacitor braze material comprising a silver-copper alloy contacting the ferrule and the metallized external surface of the capacitor;

f) wrapping a thread of the capacitor braze material about the lead and contacting the metallized internal surface of the capacitor; and

g) heating the capacitor braze material, thereby brazing the preform connecting the capacitor'"'"'s metallized external surface to the ferrule forming a capacitor-ferrule braze joint and connecting the capacitor'"'"'s metallized internal surface to the lead forming a capacitor-lead braze joint.

2. The process of claim 1 wherein the capacitor braze material comprises 72% silver and 28% copper.

3. The process of claim 1 wherein the capacitor braze material further comprises at least one of the group consisting of:

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

4. The process of claim 1 wherein the brazing further comprises the acts of:

a) placing the feedthrough in a vacuum furnace; and

b) heating the vacuum furnace to a temperature exceeding 750°

C., thereby causing the capacitor braze material to melt and flow into contact with the metallized external surface of the capacitor and the ferrule and into contact with the metallized internal surface of the capacitor and the lead; and

c) cooling the feedthrough.

5. The process of claim 1 further comprising the acts of:

a) placing the feedthrough in a vacuum furnace;

b) heating the vacuum furnace to a temperature exceeding the liquidus temperature of the capacitor braze material, thereby causing the capacitor braze material to melt and seep into contact with the metallized external surface of the capacitor and the ferrule and into contact with the lead and the metallized internal surface of the capacitor passageway; and

c) cooling the feedthrough.

6. A process for brazing an insulator and a filter capacitor in a feedthrough device, comprising the acts of:

a) providing a ferrule;

b) defining a capacitor receiving recess end an insulator receiving recess in the ferrule;

c) disposing an insulator in the insulator receiving recess, the insulator having an insulator passageway receiving a lead therethrough;

d) disposing a capacitor in the capacitor receiving recess, the capacitor defining a capacitor passageway for allowing the lead to pass therethrough, wherein the capacitor has a metallized external surface and the capacitor passageway comprises a metallized internal surface;

e) providing an insulator braze material between the insulator and the ferrule and between the insulator and the lead;

f) brazing the insulator braze material at a first temperature to connect the insulator to the ferrule and the insulator to the lead;

g) providing a capacitor braze material comprising a silver-copper alloy in the form of an annular preform contacting the capacitor and the ferrule and in the form of a thread material wrapped about the lead and contacting the metallized internal surface of the capacitor; and

h) next, brazing the capacitor to the ferrule and the capacitor to the lead using the capacitor braze material at a second temperature that is lower than the first temperature.

7. The process of claim 6, further comprising the acts of:

a) placing the feedthrough in a vacuum furnace;

b) heating the vacuum furnace to a temperature exceeding a eutectic melting temperature of the capacitor braze material flowing between the ferrule and the metallized external surface layer of the capacitor and flowing between the metallized internal surface layer of the capacitor passageway and the lead; and

c) cooling the feedthrough.

8. The process of claim 6 wherein the insulator braze material is selected from the group consisting of:

a) gold and gold alloys comprising at least one of the group consisting of;

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

b) silver and silver alloys comprising at least one of the group consisting of;

gallium, palladium, and aluminum;

c) copper silver alloys; and

d) copper silver alloys comprising at least one of the group consisting of;

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

9. A process for brazing a filter capacitor in a feedthrough device, comprising the steps of:

a) providing a ferrule defining a capacitor receiving recess;

b) disposing a capacitor in the capacitor receiving recess;

c) providing the capacitor with a passageway, the capacitor having a metallized external surface and a metallized internal surface about the capacitor passageway;

d) positioning a lead passing through the capacitor passageway;

e) providing a capacitor braze material selected from the group consisting of titanium, indium, gallium, palladium, platinum, nickel, tin, 72% silver and 28% copper, silver-germanium alloys, 99.99% pure gold, gold alloys, and silver-palladium-gallium alloys;

f) positioning an annular preform of the capacitor braze material contacting the ferrule and the metallized external surface of the capacitor;

g) wrapping a thread of the capacitor braze material about the lead and contacting the metallized internal surface of the capacitor;

h) placing the feedthrough in a vacuum furnace heated to a temperature exceeding the liquidus temperature of the capacitor braze material melting and flowing into contact with the metallized external surface of the capacitor and the ferrule and into contact with the metallized internal surface of the capacitor and the lead; and

i) cooling the feedthrough.

10. A process for brazing a filter capacitor in a feedthrough device, comprising the steps of:

a) providing a ferrule defining a capacitor receiving recess;

b) disposing a capacitor in the capacitor receiving recess;

c) providing the capacitor with a passageway, the capacitor having a metallized external surface and a metallized internal surface about the capacitor passageway;

d) positioning a lead passing through the capacitor passageway;

e) positioning an annular preform of a first capacitor braze material contacting the ferrule and the metallized external surface of the capacitor;

f) wrapping a thread of a second capacitor braze material about the lead and contacting the metallized internal surface of the capacitor, wherein the first and second capacitor braze materials are individually selected from the group consisting of;

i) 72% silver and 28% copper;

ii) copper and silver and at least one of the group consisting of titanium, indium, gallium, palladium, platinum, nickel, tin, and mixtures thereof;

iii) gold alloys;

iv) silver-germanium alloys; and

v) silver-palladium-gallium alloys; and

g) heating the first and second capacitor braze materials, thereby brazing the preform connecting the capacitor'"'"'s metallized external surface to the ferrule forming a capacitor-ferrule braze joint and connecting the capacitor'"'"'s metallized internal surface to the lead forming a capacitor-lead braze joint.