Implantable medical device having flat electrolytic capacitor formed with nonthrough-etched and through-hole punctured anode sheets

• US 6,409,776 B1
• Filed: 06/30/2000
• Issued: 06/25/2002
• Est. Priority Date: 06/30/2000
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Yan, Jenn-Feng, Crespi, Ann M., Untereker, Darrel F.
• Primary Examiner(s): NGUYEN, HA T
• Application Number:
  US09/608,576
• Time in Patent Office: 725 Days
• Field of Search: 29/250-- 2, 361/508, 361/509, 361/512, 361/517, 361/522-524, 361/528, 361/529, 607/5
• US Class Current: 29/25.03
• 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

Implantable medical devices (IMDs) and their various components, including flat electrolytic capacitors for same, and methods of making and using same, particularly an improved electrolytic capacitor with optimized ESR and anode layer surface area. An electrode stack assembly and electrolyte are located within the interior case chamber of a hermetically sealed capacitor case. The electrode stack assembly comprises a plurality of capacitor layers stacked in registration upon one another, each capacitor layer comprising a cathode layer having a cathode tab, an anode sub-assembly comprising at least one anode layer having an anode tab, and a separator layer located between adjacent anode and cathode layers, whereby all adjacent cathode layers and anode layers of the stack are electrically insulated from one another by a separator layer. Anode terminal means extend through the capacitor case side wall for electrically connecting a plurality of the anode tabs to one another and providing an anode connection terminal at the exterior of the case. Cathode terminal means extend through or to an encapsulation area of the capacitor case side wall for electrically connecting a plurality of the cathode tabs to one another and providing a cathode connection terminal at the exterior of the case. A connector assembly is electrically attached to the anode connection terminal for making electrical connection with the anode tabs and to the cathode connection terminal for making electrical connection with the cathode tabs. The anode layers are formed of one or more nonthrough-etched anode sheet bearing an oxide layer and formed with a plurality of punctures therethrough.

Claims

1. A process for making an anode layer for use in an electrolytic capacitor comprising the steps of

(a) providing a thin metallic anode foil;

(b) etching said thin metallic anode foil to form pores extending part way through the thin metallic anode foil thereby forming an etched anode foil providing enhanced surface area

(c) cutting the etched anode foil to provide first, second and third etched anode sheets each having first and second opposed major surfaces bounded by an anode sheet edge and an anode sheet thickness;

(d) forming a plurality of through-holes extending between said first and second opposed major surfaces and through said anode sheet thickness of said first and second etched anode sheets;

(e) forming an oxide layer overlying the pore and through-hole surfaces of said first and second etched anode sheet and the pore surfaces of the third etched anode sheet; and

(f) assembling said first, second and third etched anode sheets into an anode layer having the third etched anode sheet assembled between the first and second etched anode sheets.

2. The process of claim 1, wherein said step of providing a metallic foil comprises providing an aluminum foil.

3. The process of claim 1, wherein:

the cutting step (c) further comprises cutting fourth and fifth etched anode sheets;

the forming step (d) further comprises forming a plurality of through-holes extending between said first and second opposed major surfaces and through said anode sheet thickness of said fourth and fifth etched anode sheets;

the forming step (e) comprises forming an oxide layer overlying the pore and through-hole surfaces of said fourth and fifth etched anode sheets; and

the assembling step (f) comprises assembling the first major surfaces of said fourth and fifth etched anode sheets against the second major surfaces of said first and second etched anode sheets into an anode layer having the third etched anode sheet assembled between the first and fourth etched anode sheets and the second and fifth etched anode sheets.