Moisture resistant solid electrolytic capacitor assembly

Patent metadata

Field	Value
Publication number	US-9236192-B2
Application number	US-201313967462-A
Country	US
Kind code	B2
Filing date	Aug 15, 2013
Priority date	Aug 15, 2013
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

A capacitor assembly that contains a solid electrolytic capacitor element positioned within a multi-layered casing is provided. The casing contains an encapsulant layer that overlies the capacitor element and a moisture barrier layer that overlies the encapsulant layer. Through careful control of the materials employed in the casing, the present inventor has discovered that the resulting capacitor assembly can be mechanically stable while also exhibiting electrical properties in the presence of high humidity levels (e.g., relative humidity of 85%). For example, the encapsulant layer may be formed from a thermoset resin (e.g., epoxy) that is capable of providing the capacitor element with mechanical stability. The moisture barrier layer may likewise be formed from a hydrophobic material.

First claim

What is claimed is:

1. A capacitor assembly comprising:
a capacitor element comprising a sintered porous anode body, a dielectric layer that overlies the anode body, and a solid electrolyte overlying the dielectric layer; and
a multi-layered casing within which the capacitor element is positioned, wherein the casing contains an encapsulant layer that overlies the capacitor element and a moisture barrier layer that overlies the encapsulant layer, the encapsulant layer containing a thermoset resin, wherein the thermoset resin is an epoxy resin, and the moisture barrier layer containing a hydrophobic material, wherein the hydrophobic material includes an elastomer, wherein the elastomer is a silicone containing one or more fluorinated hydrocarbon groups.

2. The capacitor assembly of claim 1 , wherein the hydrophobic material has a contact angle with water of about 90° or more, as determined in accordance with ASTM D7490-08.

3. The capacitor assembly of claim 1 , wherein the fluorinated hydrocarbon groups are perfluoroalkylene groups represented by the following general formula:
C p F 2p+1 C q H 2q

wherein
p is an integer from 1 to 12; and
q is an integer from 0 to 8.

4. The capacitor assembly of claim 3 , wherein p is an integer from 2 to 10; and q is an integer from 2 or 3.

5. The capacitor assembly of claim 3 , wherein the fluorinated hydrocarbon groups are CF 3 —C 2 H 4 —, C 4 F 9 —C 2 H 4 —, C 6 F 13 —C 2 H 4 —, C 8 F 17 —C 2 H 4 —, C 8 F 17 —C 3 H 6 —, CF 3 —, C 3 F 7 —, C 4 F 9 —, C 8 F 17 —, C 6 F 13 , or a combination thereof.

6. The capacitor assembly of claim 1 , wherein the encapsulant layer contains a non-conductive filler.

7. The capacitor assembly of claim 6 , wherein the nonconductive filler includes silica, silicate, or a combination thereof.

8. The capacitor assembly of claim 1 , wherein the moisture barrier layer covers only a portion of the encapsulant layer.

9. The capacitor assembly of claim 1 , wherein at least a portion of the moisture barrier layer has a thickness of from about 5 nanometers to about 5 micrometers.

10. The capacitor assembly of claim 1 , wherein the anode body is formed from a powder that contains tantalum, niobium, or an electrically conductive oxide thereof.

11. The capacitor assembly of claim 1 , wherein the solid electrolyte contains a conductive polymer.

12. The capacitor assembly of claim 11 , wherein the conductive polymer is poly(3,4-ethylenedioxythiophene).

13. The capacitor assembly of claim 11 , wherein the solid electrolyte comprises a plurality of pre-polymerized conductive polymer particles.

14. The capacitor assembly of claim 11 , wherein the solid electrolyte further contains a hydroxyl-functional nonionic polymer.

15. The capacitor assembly of claim 1 , further comprising an anode termination that is in electrical connection with the anode body and a cathode termination that is in electrical connection with the solid electrolyte, wherein the casing leaves at least a portion of the anode termination and the cathode termination exposed.

16. The capacitor assembly of claim 15 , wherein an anode lead extends from the anode body and is connected to the anode termination.

17. The capacitor assembly of claim 1 , wherein after exposure to an atmosphere having a relative humidity of 85%, the capacitor assembly exhibits an ESR of less than about 50 ohms, as measured at an operating frequency of 100 kHz.

Assignees

• Avx Corp

Inventors

• Biler Martin
• Vilc Ladislav

Classifications

• H01G9/012

  specially adapted for solid capacitors · CPC title

• H01G9/08

  Housing; Encapsulation · CPC title

• H01G9/025

  Solid electrolytes (H01G11/54 takes precedence) · CPC title

• H01G9/15

  Solid electrolytic capacitors (H01G11/00 takes precedence) · CPC title

• H01G9/10 Primary

  Sealing, e.g. of lead-in wires · CPC title