Casing material for a solid electrolytic capacitor

Patent metadata

Field	Value
Publication number	US-10643797-B2
Application number	US-201715810445-A
Country	US
Kind code	B2
Filing date	Nov 13, 2017
Priority date	Nov 15, 2016
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A capacitor assembly that is capable of performing well under the conditions of high humidity and temperature (e.g., 85% relative humidity/85° C.) is provided. The capacitor assembly comprises a solid electrolytic capacitor element, an anode termination that is in electrical connection with the anode body, cathode termination that is in electrical connection with the solid electrolyte, and casing material that encapsulates the capacitor element and leaves exposed at least a portion of the anode termination and the cathode termination. The casing material is formed from an epoxy composition that contains one or more inorganic oxide fillers and a resinous material that includes one or more epoxy resins crosslinked with a co-reactant, wherein inorganic oxide fillers about 75 wt. % or more of the epoxy composition, and vitreous silica constitutes about 30 wt. % or more of the total weight of inorganic oxide fillers in the epoxy composition.

First claim

What is claimed is:

1. A capacitor assembly comprising:
a solid electrolytic capacitor element that contains a sintered porous anode body wherein the anode body comprises tantalum, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric;
an anode termination that is in electrical connection with the anode body;
a cathode termination that is in electrical connection with the solid electrolyte; and
a casing material that encapsulates the capacitor element and leaves exposed at least a portion of the anode termination and the cathode termination, wherein the casing material is formed from an epoxy composition that contains one or more inorganic oxide fillers and a resinous material that includes one or more epoxy resins crosslinked with a co-reactant, wherein inorganic oxide fillers constitute about 75 wt. % or more of the epoxy composition, and vitreous silica constitutes about 30 wt. % or more of the total weight of inorganic oxide fillers in the epoxy composition.

2. The capacitor assembly claim 1 , wherein vitreous silica constitutes from about 20 wt. % to about 70 wt. % of the epoxy composition.

3. The capacitor assembly of claim 1 , wherein the resinous material constitutes from about 0.5 wt. % to about 25 wt. % of the epoxy composition.

4. The capacitor assembly of claim 1 , wherein the epoxy resin is a phenolic novolac epoxy resin.

5. The capacitor assembly of claim 1 , wherein the phenolic novolac epoxy resin is a phenol-novolac epoxy resin, cresol-novolac epoxy resin, naphthol-novolac epoxy resin, naphthol-phenol co-condensation novolac epoxy resin, naphthol-cresol co-condensation novolac epoxy resin, brominated phenol-novolac epoxy resin, or a combination thereof.

6. The capacitor assembly of claim 1 , wherein the co-reactant is a polyamide, amidoamines, aromatic diamine, aminobenzoates, aliphatic amines, cycloaliphatic amines, imidazole derivative, guanidine, carboxylic acid anhydrides, carboxylic acid hydrazides, phenolic-novolac resin, carboxylic acid amide, or a combination thereof.

7. The capacitor assembly of claim 1 , wherein the co-reactant is a phenolic-novolac resin.

8. The capacitor assembly of claim 1 , wherein the capacitor element further comprises a cathode coating that contains a metal particle layer that overlies the solid electrolyte, wherein the metal particle layer includes a plurality of conductive metal particles dispersed within a resinous polymer matrix.

9. The capacitor assembly of claim 8 , wherein the metal particles include silver.

10. The capacitor assembly of claim 1 , wherein the solid electrolyte includes a plurality of conductive polymer particles.

11. The capacitor assembly of claim 10 , wherein the conductive polymer particles contain an extrinsically conductive polymer having repeating units of the following formula (III):

wherein,
R 7 is a linear or branched, C 1 to C 18 alkyl radical, C 5 to C 12 cycloalkyl radical, C 6 to C 14 aryl radical, C 7 to C 18 aralkyl radical, or a combination thereof; and
q is an integer from 0 to 8.

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

13. The capacitor assembly of claim 11 , wherein the particles also contain a polymeric counterion.

14. The capacitor assembly of claim 10 , wherein the conductive polymer particles contain an intrinsically conductive polymer having repeating units of the following formula (IV):

wherein,
R is (CH 2 ) a —O—(CH 2 ) b ;
a is from 0 to 10;
b is from 1 to 18;
Z is an anion;
X is a cation.

15. The capacitor assembly of claim 1 , further comprising an external polymer coating that overlies the solid electrolyte and contains pre-polymerized conductive polymer particles and a cross-linking agent.

16. The capacitor assembly of claim 1 , wherein the capacitor is in contact with an atmosphere having a relative humidity of about 40% or more.

17. The capacitor assembly of claim 1 , further comprising a moisture barrier layer that coats at least a portion of the casing material.

18. The capacitor assembly of claim 17 , wherein the moisture barrier layer includes a silicone elastomer.

Assignees

• Avx Corp

Inventors

• Vilc Ladislav
• Stabl Marek
• Horacek Ivan

Classifications

• H01G9/15

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

• H01G9/012

  specially adapted for solid capacitors · CPC title

• H01G9/08 Primary

  Housing; Encapsulation · CPC title

• H01G9/0036

  Formation of the solid electrolyte layer · CPC title

• H01G9/025

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