Electrolytic capacitor and multi-anodic attachment

• US 20040105212A1
• Filed: 07/10/2003
• Published: 06/03/2004
• Est. Priority Date: 04/21/1998
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Poplett, James M., Tong, Robert R., Waytashek, Brian V., Barr, Alexander Gordon, Christenson, Luke J., OʼPhelan, Michael J.
• Granted Patent: US 6,881,232 B2
• Time in Patent Office: Days
• US Class Current: 361/302
• CPC Class Codes: H01G 9/008 Terminals
• CPC Class Codes: H01G 9/04 Electrodes or formation of dielectric layers thereon
• CPC Class Codes: H01G 9/055 Etched foil electrodes

Abstract

A multi-anodic aluminum electrolytic capacitor includes an electrical connection to the multiple porous (e.g., tunnel-etched) anodes in an anode stack using a single anode tab that is attached only to a first anode. Other anodes are electrically coupled to the anode tab through the first anode. Anodes in the anode stack are in intimate physical and electrical contact with other such anodes as a result of layering effected by planar stacking or cylindrical winding. The need for separate tabs to different anode layers is eliminated or at least minimized, thereby reducing capacitor volume, increasing capacitor reliability, and reducing the cost and complexity of the capacitor manufacturing process for multi-anodic capacitors. The capacitor is capable of use in implantable defibrillators, camera photoflashes, and other electric circuit applications.

Claims

1. A capacitor, comprising:

a first anode;

a cathode;

a separator between the first anode and the cathode, the separator carrying an electrolyte;

a tab, physically and electrically coupled to the first anode; and

a second anode that is physically separated from the tab and electrically coupled to the tab through the first anode, wherein the unjoined first and second anodes are electrically intercoupled by physical contact between the first and second anodes.

2. The capacitor of claim 1, in which the first and second anodes are physically and electrically intercoupled by physical contact between the first and second anodes at a plurality of points.

3. The capacitor of claim 2, in which the first and second anodes are physically and electrically intercoupled by physical contact between the first and second anodes at a plurality of points distributed throughout an interface between the first and second anodes.

4. The capacitor of claim 3, further comprising a dielectric that includes oxidized portions of the first anode.

5. The capacitor of claim 4, in which the dielectric includes oxidized portions of the first and second anodes.

6. The capacitor of claim 1, in which the physical contact between the first and second anodes is effected by a planar layering of the first and second anodes.

7. The capacitor of claim 1, in which the physical contact between the first and second anodes is effected by a cylindrically wound layering of the first and second anodes.

8. The capacitor of claim 1, in which the first and second anodes, the separator, and the cathode are arranged in an approximately planar and approximately superjacent configuration.

9. The capacitor of claim 1, in which the first and second anodes, the separator, and the cathode include strips that are wound in an approximately cylindrical configuration.

10. The capacitor of claim 1, in which at least one of the first and second anodes is porous.

11. The capacitor of claim 10, in at least one of the first and second anodes includes tunnel-etched aluminum foil.

12. An implantable cardiac rhythm management system including the capacitor of claim 1.

13. The system of claim 12, further comprising:

an implantable defibrillator carrying the capacitor; and

a leadwire that is adapted to be coupled to a heart for delivering an electrical countershock energy that is stored on the capacitor.

14. A capacitor, comprising:

a first anode;

a cathode;

a separator between the first anode and the cathode, the separator carrying a conductive electrolyte;

a tab, physically and electrically coupled to the first anode;

a second anode that is physically separated from the tab and electrically coupled to the tab through the first anode;

a dielectric including oxide on at least one surface of the first and second anodes, the dielectric electrically isolating the first and second anodes from the electrolyte and the cathode; and

wherein the first and second anodes are physically layered in intimate contact with each other, thereby breaking through portions of the oxide on opposing surfaces of the first and second anodes and resulting in electrical contact between the first and second anodes.

15. The capacitor of claim 14, in which at least one of the first and second anodes is porous.

16. The capacitor of claim 15, in at least one of the first and second anodes includes tunnel-etched aluminum foil.

17. The capacitor of claim 14, in which the first and second anodes, the separator, and the cathode are arranged in an approximately planar and approximately superjacent configuration.

18. The capacitor of claim 14, in which the first and second anodes, the separator, and the cathode include strips that are wound in an approximately cylindrical configuration.

19. An implantable cardiac rhythm management system including the capacitor of claim 14.

20. The system of claim 19, further comprising:

an implantable defibrillator carrying the capacitor; and

a leadwire that is adapted to be coupled to a heart for delivering an electrical countershock energy that is stored on the capacitor.

21. A capacitor, comprising:

a first anode;

a cathode;

a separator between the first anode and the cathode, the separator carrying a conductive electrolyte;

a tab, physically and electrically coupled to the first anode;

a plurality of second anodes, each second anode being physically separated from the tab and electrically coupled to the tab through the first anode;

a dielectric including oxidized portions of ones of the first and second anodes, the dielectric electrically isolating the first and second anodes from the electrolyte and the cathode; and

wherein the unjoined first and second anodes are physically and electrically intercoupled by physical contact between the first and second anodes.

22. The capacitor of claim 21, in which the first and second anodes are physically layered in intimate contact with each other, thereby breaking through portions of the oxide on opposing surfaces of the first and second anodes and resulting in electrical contact between the first and second anodes.

23. The capacitor of claim 21, in which the first and second anodes, the separator, and the cathode are arranged in an approximately planar and approximately superjacent configuration.

24. The capacitor of claim 21, in which the first and second anodes, the separator, and the cathode include strips that are wound in an approximately cylindrical configuration.

25. The capacitor of claim 21, in which at least one of the first and second anodes is porous.

26. The capacitor of claim 25, in at least one of the first and second anodes includes tunnel-etched aluminum foil.

27. An implantable cardiac rhythm management system including the capacitor of claim 21.

28. The system of claim 27, further comprising:

an implantable defibrillator carrying the capacitor; and

a leadwire that is adapted to be coupled to a heart for delivering an electrical countershock energy that is stored on the capacitor.

29. A method of forming a capacitor, the method comprising:

disposing a separator between a first anode and a cathode, the separator carrying a conductive electrolyte;

physically and electrically coupling a tab to the first anode;

disposing a second anode to be physically separated from the tab; and

electrically coupling a second anode to the tab through the first anode by physically contacting the unjoined first and second electrodes.

30. The method of claim 29, further including arranging the first and second anodes, the separator, and the cathode in an approximately planar and approximately superjacent configuration.

31. The method of claim 29, further including winding strips of the first and second anodes, the separator, and the cathode in an approximately cylindrical configuration.

32. The method of claim 29, in which electrically coupling a second anode to the tab through the first anode comprises physically layering the first and second anodes in intimate contact with each other, thereby breaking through portions of the oxide on opposing surfaces of the first and second anodes and resulting in electrical contact between the first and second anodes.

33. A method forming an anode stack for a cylindrical capacitor, the method comprising:

providing two or more conductive ribbons, each having an insulative coating; and

winding portions of the conductive ribbons around an axis with sufficient force to establish electrical contact of two or more of the conductive ribbons through their respective insulative coatings.

34. The method of claim 33, wherein each insulative coatings consists essentially of an oxide.

35. The method of claim 33, wherein no more than one of every two conductive ribbons is joined to an anode tab.

36. The method of claim 35, wherein the anode tab is oriented transverse to a length dimension of each ribbon.

37. The method of claim 33, wherein no more than one of every three conductive ribbons is joined to an anode tab.

38. The method of claim 33, wherein winding portions of the conductive ribbons around an axis with sufficient force to establish electrical contact of two or more of the conductive ribbons through their respective insulative coatings comprises:

providing a dual anode lug capacitor winder; and

operating the winder at a tension setting of 1.5 for at least two of the conductive ribbons.