Delamination-resistant solid electrolytic capacitor

Patent metadata

Field	Value
Publication number	US-11222755-B2
Application number	US-202016874748-A
Country	US
Kind code	B2
Filing date	May 15, 2020
Priority date	May 17, 2019
Publication date	Jan 11, 2022
Grant date	Jan 11, 2022

Abstract

A solid electrolytic capacitor that comprises a capacitor element that contains a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric is provided. An anode lead wire extends from the capacitor element in a longitudinal direction, wherein the lead wire defines an external surface having a plurality of distinct recessed regions that are spaced apart along the longitudinal direction. A hydrophobic coating is disposed on at least a portion of the external surface of the anode lead wire. Further, an anode termination is in electrical connection with the anode lead wire and a cathode termination is in electrical connection with the solid electrolyte.

First claim

What is claimed is:

1. A solid electrolytic capacitor comprising:
a capacitor element that contains a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric;
an anode lead wire extending from the capacitor element in a longitudinal direction, wherein the lead wire defines an external surface having a plurality of distinct recessed regions that are spaced apart along the longitudinal direction, wherein the recessed regions are formed at an angle of from about 40° to about 120° relative to the longitudinal direction of the wire;
a hydrophobic coating that is disposed on at least a portion of the external surface of the anode lead wire; and
an anode termination that is in electrical connection with the anode lead wire and a cathode termination that is in electrical connection with the solid electrolyte.

2. The solid electrolytic capacitor of claim 1 , wherein the lead wire is formed from tantalum.

3. The solid electrolytic capacitor of claim 1 , wherein the lead wire extends from a front surface of the capacitor element.

4. The solid electrolytic capacitor of claim 1 , wherein the wire contains from 3 to 50 recessed regions.

5. The solid electrolytic capacitor of claim 1 , wherein the recessed regions extend about a periphery of the lead wire to form a series of bands.

6. The solid electrolytic capacitor of claim 1 , wherein the recessed regions extend in a direction that is generally perpendicular to the longitudinal direction of the wire.

7. The solid electrolytic capacitor of claim 1 , wherein the hydrophobic coating is also in contact with at least a portion of the anode termination.

8. The solid electrolytic capacitor of claim 1 , wherein the coating comprises a hydrophobic resinous material.

9. The solid electrolytic capacitor of claim 8 , wherein the hydrophobic resinous material contains a fluoropolymer.

10. The solid electrolytic capacitor of claim 9 , wherein the fluoropolymer is formed from a fluoroalkyl-substituted ethylenically unsaturated monomer.

11. The solid electrolytic capacitor of claim 10 , wherein the fluoropolymer is formed from a fluoroalkyl (meth)acrylate.

12. The solid electrolytic capacitor of claim 1 , further comprising a casing material that encapsulates the capacitor element and anode lead wire.

13. The solid electrolytic capacitor of claim 1 , wherein the anode body includes tantalum.

14. The solid electrolytic capacitor of claim 1 , wherein the solid electrolyte includes a conductive polymer.

15. The solid electrolytic capacitor of claim 14 , wherein the conductive polymer has repeating units of the following formula:

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.

16. The solid electrolytic capacitor of claim 15 , wherein the conductive polymer is poly(3,4-ethylenedioxythiophene) or a derivative thereof.

17. The solid electrolytic capacitor of claim 15 , wherein the solid electrolyte also contains a polymeric counterion.

18. The solid electrolytic capacitor 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.

19. The solid electrolytic capacitor of claim 1 , wherein the recessed regions have a depth of from about 0.1 to about 100 micrometers.

20. The solid electrolytic capacitor of claim 1 , wherein the recessed regions are spaced apart a distance ranging from 0.01 to about 300 micrometers.

21. The solid electrolytic capacitor of claim 1 , wherein the recessed regions have a width of from about 1 to about 160 micrometers.

22. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an initial ESR at a temperature of about 23° C. and a high humidity ESR after being subjected to a relative humidity of about 85% and temperature of about 85° C. for 1,000 hours, wherein the ratio of the high humidity ESR to the initial ESR is about 2.0 or less.

23. The solid electrolytic capacitor of claim 1 , wherein the ratio of the high humidity ESR to the initial ESR is about 1.5 or less.

24. A method for forming the solid electrolytic capacitor of claim 1 , the method comprising:
roughening the anode lead wire to form the plurality of recessed regions;
disposing a coating formulation on the anode lead wire in contact with the recessed regions.

25. The method of claim 24 , wherein the coating formulation contains a hydrophobic resinous material and a solvent, and wherein the solvent is removed from the coating formulation after contact with the lead wire to form the hydrophobic coating.

26. The method of claim 25 , wherein the solvent includes a fluorinated hydrocarbon solvent.

27. The method of claim 24 , wherein the roughening includes contacting the lead wire with a laser.

28. A solid electrolytic capacitor comprising:
a capacitor element that contains a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric;
an anode lead wire extending from the capacitor element in a longitudinal direction, wherein the lead wire defines an external surface having a plurality of distinct recessed regions that are spaced apart along the longitudinal direction, wherein the recessed regions have a depth of from about 0.1 to about 100 micrometers;
a hydrophobic coating that is disposed on at least a portion of the external surface of the anode lead wire; and
an anode termination that is in electrical connection with the anode lead wire and a cathode termination that is in electrical connection with the solid electrolyte.

29. The solid electrolytic capacitor of claim 28 , wherein the wire contains from 3 to 50 recessed regions.

30. The solid electrolytic capacitor of claim 28 , wherein the recessed regions extend about a periphery of the lead wire to form a series of bands.

31. The solid electrolytic capacitor of claim 28 , wherein the recessed regions extend in a direction that is generally perpendicular to the longitudinal direction of the wire.

32. The solid electrolytic capacitor of claim 28 , wherein the coating comprises a hydrophobic resinous material.

33. The solid electrolytic capacitor of claim 32 , wherein the hydrophobic resinous material contains a fluoropolymer formed from a fluoroalkyl-substituted ethylenically unsaturated monomer.

34. The solid electrolytic capacitor of claim 28 , wherein the solid electrolyte includes a conductive polymer having repeating units of the following formula:

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.

35. The solid electrolytic capacitor of claim 28 , further comprising an external polymer coating that overlies the solid

Assignees

• Avx Corp
• Kyocera Avx Components Corp

Inventors

• Tezuka Yasuyuki

Classifications

• H01G9/15 Primary

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

• H01G9/012

  specially adapted for solid capacitors · CPC title

• H01G9/004

  Details · CPC title

• H01G9/028

  Organic semiconducting electrolytes, e.g. TCNQ · CPC title

• H01G9/048

  characterised by their structure (H01G11/22 takes precedence) · CPC title