Capacitors having metallized film with tapered thickness

• US 6,187,028 B1
• Filed: 04/23/1998
• Issued: 02/13/2001
• Est. Priority Date: 04/23/1998
• Status: Expired due to Fees

• Current Assignee: Intermedics Incorporated (Boston Scientific Corporation)
• Original Assignee: Intermedics Incorporated (Boston Scientific Corporation)
• Inventors: Munshi, Mohammed Zafar Amin
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/065,131
• Time in Patent Office: 1,027 Days
• Field of Search: 361/301.1, 361/301.5, 361/303, 361/311, 361/373, 29/254.2, 607/1
• US Class Current: 607/1
• CPC Class Codes: H01G 4/015 Special provisions for self-healing
• CPC Class Codes: H01G 4/18 of synthetic material, e.g. derivatives of cellulose H01G4/16 takes precedence
• CPC Class Codes: H01G 4/32 Wound capacitors

Abstract

A thin film capacitor for use in an implantable defibrillator. A first dielectric polymer filmlayer has a metallized film on one side thereof. A second dielectric polymer film layer has a metallized film on one side thereof. The first and second layers are overlain on each other and wound spirally with the metallized film of one layer adjacent the dielectric polymer of the other layer. The beginnings and ends of the first and second metallized films are offset from the respective beginnings and ends of the first and second polymer film layers. The dielectric layers can be tapered in increasing thickness toward the respective beginnings and ends of the layers. The dielectric layers can themselves comprise at least two layers of differing polymer materials, the preferred materials being polyvinylidene fluoride and polyester for improved energy density and self-healing properties.

Claims

1. A capacitor comprising:

a first dielectric polymer film layer having a metallized film on at least one side thereof and having a beginning and an end;

a second dielectric polymer film layer having a metallized film on at least one side thereof and having a beginning and an end;

the first and second layers being overlain on each other with the metallized film on one layer adjacent the dielectric polymer of the other layer; and

the first layer having a middle portion of substantially uniform thickness and a first portion that tapers in increasing thickness from said middle portion to the beginning portion of the first layer and a second portion that tapers in increasing thickness from the middle portion to the end portion of the first layer.

2. The capacitor of claim 1, in which the first portion of the first layer tapers in thickness over a distance in a direction substantially perpendicular to a winding axis at least several multiples of a circumference of a mandrel.

3. The capacitor of claim 1, in which the second portion of the first layer tapers in increasing thickness over a distance in a direction substantially perpendicular to a winding axis of at least several multiples of a circumference of a mandrel.

4. The capacitor of claim 1, wherein the second layer comprises a middle portion of substantially uniform thickness and a first portion that tapers in increasing thickness from the middle portion to the beginning portion of the second layer and a second portion that tapers in increasing thickness from the middle portion to the end portion of the second layer.

5. A capacitor comprising:

a first dielectric film having an end portion, a middle portion, and a first portion that tapers from the middle portion to the end portion in a direction substantially perpendicular to a winding axis, with the first portion having a length, in a direction substantially perpendicular to a winding axis, greater than a circumference of an associated winding mandrel; and

a second dielectric film layer adjacent the first dielectric film.

6. The capacitor of claim 5 wherein the first portion of the first dielectric film tapers in increasing thickness from the middle portion to the end portion.

7. The capacitor of claim 5, wherein the first dielectric film layer has a second portion that tapers from the middle portion to the end portion, with the second portion having a length, in a direction substantially perpendicular to a winding axis, greater than a circumference of an associated winding mandrel.

8. The capacitor of claim 5 wherein the first and second dielectric film consist essentially of a polymer.

9. The capacitor of claim 8 further comprising first and second conductive films contacting respectively the first and second dielectric films.

10. A capacitor comprising:

a first metallized dielectric polymeric layer having an end portion, a middle portion, and a first portion that tapers in increasing thickness from the middle portion to the end portion in a direction substantially perpendicular to a winding axis, with the first portion having a first length, in a direction substantially perpendicular to a winding axis, greater than a circumference of an associated winding mandrel; and

a second metallized polymeric layer adjacent the first dielectric layer and having an end portion, a middle portion, and a second portion that tapers in increasing thickness from the middle portion to the end portion in a direction substantially perpendicular to the winding axis, with the second portion having a second length, in the direction substantially perpendicular to the winding axis, greater than the circumference of the associated winding mandrel.

11. A capacitor in an implantable medical device, comprising:

a first dielectric layer having a metallized film on at least one side thereof and having a beginning and an end and means between the beginning and the end for reducing a likelihood of failures in the first dielectric layer;

a second dielectric layer adjacent the first dielectric film and having a metallized film on at least one side thereof.