Implantable medical device having flat electrolytic capacitor with laser welded cover

• US 6,118,652 A
• Filed: 06/24/1998
• Issued: 09/12/2000
• Est. Priority Date: 04/03/1998
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Johnson, William L., Breyen, Mark D., Casby, Kurt J., Nutzman, Thomas M., Rorvick, Anthony R.
• Primary Examiner(s): Kincaid, Kristine
• Assistant Examiner(s): Thomas, Eric W.
• Application Number:
  US09/104,311
• Time in Patent Office: 811 Days
• Field of Search: 361/517, 361/502, 361/503, 361/508, 361/518, 361/519, 361/520, 361/535, 361/536, 361/537, 361/538, 361/539, 607/5, 174/17 R, 174/50, 174/50.54
• US Class Current: 361/517
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3968 Constructional arrangements, e.g. casings A61N1/375 takes precedence

Abstract

An implantable medical device such as a defibrillator is described. The device includes an hermetically sealed housing containing a flat electrolytic capacitor and an energy source such as a battery. The battery is connected to the capacitor and provides charge thereto. The capacitor stores the charge at a relatively high voltage. The charge stored in the capacitor is discharged through a defibrillation lead to a site on or in the heart when fibrillation of the heart is detected by the implantable medical device. Methods of making and using the implantable medical device, the capacitor, and their various components are disclosed.

Claims

1. An hermetically sealed implantable medical device, comprising:

(a) an hermetically sealed housing;

(b) an energy source disposed within the housing;

(c) a substantially flat electrolytic capacitor connected to the energy source and disposed within the housing, the capacitor comprising;

(i) at least one flat cathode layer formed of cathode foil;

(ii) a plurality of flat anode layers formed of anode foil, the plurality of anode layers forming an anode sub-assembly having top and bottom surfaces;

(iii) at least a first separator layer formed of separator material;

(iv) an electrolyte;

(v) a case formed of a base, the base having a base inner surface, a base outer surface, and a base edge, and a case wall extending upwardly from the base edge to a case upper edge defining a case opening into the case, the case wall having a case wall thickness between inner and outer case sidewalls, the outer sidewall extending upwardly from the base edge and terminating in an upper portion of the case upper edge disposed between the inner and outer sidewalls, the inner sidewall extending upwardly from the base inner surface to a lower portion of the case upper edge within the case wall thickness, the upper and lower portions of the case upper edge joined by an intermediate sidewall of said case wall between said inner sidewall and said outer sidewall, the intermediate sidewall having an intermediate sidewall width between the upper and lower portions of the case upper edge, whereby a raised portion of the case wall is defined between the upper and lower portions of the case upper edge and the case opening is defined within the raised portion;

(vi) a substantially planar cover sealing the case opening, the cover having outer and inner surfaces separated by a cover edge and having a cover thickness that is less than the intermediate sidewall width, the cover dimensioned to fit within said case opening and to be joined at a joint along a portion of the cover inner surface or cover edge with said lower portion of the case upper edge when the raised portion is crimped or folded inwardly over or along the outer surface of the cover, the joint being welded to hermetically seal the cover to the case wall; and

wherein the at least one cathode layer, the plurality of anode layers and the first separator layer are vertically stacked inside the case such that the first separator layer is disposed between the at least one cathode layer and the anode sub-assembly, and the electrolyte is disposed inside the case.

2. The implantable medical device of claim 1, wherein the at least one cathode layer has no holes for registration disposed therethrough.

3. The implantable medical device of claim 1, wherein the plurality of flat anode layers have no holes for registration disposed therethrough.

4. The implantable medical device of claim 1, wherein the cover edge is shaped to engage the lower portion of the case upper edge such that the cover self-registers on the case opening when the cover is disposed over the lower portion.

5. The implantable medical device of claim 1, wherein the cathode foil is aluminum foil.

6. The implantable medical device of claim 1, wherein the anode foil is aluminum foil.

7. The implantable medical device of claim 1, wherein the capacitor is an aluminum electrolytic capacitor.

8. The implantable medical device of claim 1, wherein the case is formed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy, and stainless steel.

9. The implantable medical device of claim 1, wherein the cover is formed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy, and stainless steel.

10. The implantable medical device of claim 1, wherein the case or cover includes at least one alignment feature for establishing a reference position in the joint.

11. The implantable medical device of claim 1, wherein the implantable medical device is selected from the group consisting of a PCD, an AID, an ICD, a defibrillator, an implantable pulse generator and a pacemaker.

12. The implantable medical device of claim 1, wherein the energy source is selected from the group consisting of a battery, an electrochemical cell, a primary electrochemical cell , a secondary or rechargeable electrochemical cell, an electrochemical cell comprising a lithium-containing anode, an electrochemical cell comprising a silver vanadium oxide-containing cathode, an electrochemical cell comprising a (CF_n)_x -containing cathode, an electrochemical cell comprising a cathode containing a mixture of silver vanadium oxide and (CF_n)_x, a spirally wound electrochemical cell, an electrochemical cell having a plurality of plate-shaped electrodes, and an electrochemical cell having at least one serpentine electrode disposed therewithin.

13. The implantable medical device of claim 1, wherein the at least one cathode layer is electrically connected to the case.

14. The implantable medical device of claim 1, wherein the case is connected electrically to neither the at least one cathode layer nor to the plurality of anode layers.

15. The implantable medical device of claim 1, wherein the electrolyte is selected from the group consisting of a liquid electrolyte, an adhesive electrolyte and a solid electrolyte.

16. The implantable medical device of claim 1, wherein the upper edge defines a first imaginary axis extending in a first direction and the cover edge defines a second imaginary axis extending in a second direction, an angle theta defining the angle between the first and second directions after the raised portion is crimped or folded inwardly over or along the upper surface of the cover, the angle theta being less than ninety degrees but greater than or equal to zero degrees.

17. A substantially flat electrolytic capacitor, comprising:

(a) at least one flat cathode layer formed of cathode foil;

(b) a plurality of flat anode layers formed of anode foil, the plurality of anode layers forming an anode sub-assembly having top and bottom surfaces;

(c) at least a first separator layer formed of separator material;

(d) an electrolyte;

(e) a case formed of a base, the base having a base inner surface, a base outer surface, and a base edge, and a case wall extending upwardly from the base edge to a case upper edge defining a case opening into the case, the case wall having a case wall thickness between inner and outer case sidewalls, the outer sidewall extending upwardly from the base edge and terminating in an upper portion of the case upper edge disposed between the inner and outer sidewalls, the inner sidewall extending upwardly from the base inner surface to a lower portion of the case upper edge within the case wall thickness, the upper and lower portions of the case upper edge joined by an intermediate sidewall of said case wall between said inner sidewall and said outer sidewall, the intermediate sidewall having an intermediate sidewall width between the upper and lower portions of the case upper edge, whereby a raised portion of the case wall is defined between the upper and lower portions of the case upper edge and the case opening is defined within the raised portion;

(f) a substantially planar cover sealing the case opening, the cover having outer and inner surfaces separated by a cover edge and having a cover thickness that is less than the intermediate sidewall width, the cover dimensioned to fit within said case opening and to be joined at a joint along a portion of the cover inner surface or cover edge with said lower portion of the case upper edge when the raised portion is crimped or folded inwardly over or along the outer surface of the cover, the joint being welded to hermetically seal the cover to the case wall; and

wherein the at least one cathode layer, the plurality of anode layers and the first separator layer are vertically stacked inside the case such that the first separator layer is disposed between the at least one cathode layer and the anode sub-assembly, and the electrolyte is disposed inside the case.

18. The capacitor of claim 17, wherein the at least one cathode layer has no holes for registration disposed therethrough.

19. The capacitor of claim 17, wherein the plurality of flat anode layers have no holes for registration disposed therethrough.

20. The capacitor of claim 17, wherein the cover edge is shaped to engage the lower portion of the case upper edge such that the cover self-registers on the case opening when the cover is disposed over the lower portion.

21. The capacitor of claim 17, wherein the cathode foil is aluminum foil.

22. The capacitor of claim 17, wherein the anode foil is aluminum foil.

23. The capacitor of claim 17, wherein the capacitor is an aluminum electrolytic capacitor.

24. The capacitor of claim 17, wherein the case is formed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy and stainless steel.

25. The capacitor of claim 17, wherein the cover is formed of a material selected from the group consisting of aluminum, aluminum alloy, titanium, titanium alloy and stainless steel.

26. The capacitor of claim 17, wherein the case or cover includes at least one alignment feature for establishing a reference position in the joint.

27. The capacitor of claim 17, wherein the at least one cathode layer is electrically connected to the case.

28. The capacitor of claim 17, wherein the case is connected electrically to neither the at least one cathode layer nor to the plurality of anode layers.

29. The capacitor of claim 17, wherein the electrolyte is selected from the group consisting of a liquid electrolyte, an adhesive electrolyte and a solid electrolyte.

30. The capacitor of claim 17, wherein the upper edge defines a first imaginary axis extending in a first direction and the cover edge defines a second imaginary axis extending in a second direction, an angle theta defining the angle between the first and second directions after the raised portion is crimped or folded inwardly over or along the upper surface of the cover, the angle theta being less than ninety degrees but greater than or equal to zero degrees.