Protective coating for electrolytic capacitors

• US 6,674,635 B1
• Filed: 06/11/2002
• Issued: 01/06/2004
• Est. Priority Date: 06/11/2001
• Status: Expired due to Term

• Current Assignee: Kyocera AVX Components Corporation (Kyocera Corporation)
• Original Assignee: AVX Corporation (Kyocera Corporation)
• Inventors: Fife, James A., Sebald, Zebbie L.
• Primary Examiner(s): Dinkins, Anthony
• Application Number:
  US10/167,041
• Time in Patent Office: 574 Days
• Field of Search: 361/523, 361/528, 361/529, 361/524, 29/250.3
• US Class Current: 361/523
• CPC Class Codes: H01G 11/48 Conductive polymers
• CPC Class Codes: H01G 11/56 Solid electrolytes, e.g. gels; Additives therein
• CPC Class Codes: H01G 9/025 Solid electrolytes H01G11/54 takes precedence
• CPC Class Codes: H01G 9/028 Organic semiconducting electrolytes, e.g. TCNQ
• CPC Class Codes: H01G 9/042 characterised by the material H01G11/22 takes precedence
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

A solid electrolytic capacitor having an anode that contains a valve-action metal (e.g., tantalum, niobium, and the like) and a dielectric film overlying the anode is provided. The capacitor also include a protective coating overlying the dielectric film, wherein the protective coating contains a relatively insulative, resinous material. For example, in one embodiment, the resinous material can be a drying oil, such as olive oil, linseed oil, tung oil, castor oil, soybean oil, shellac, and derivatives thereof. The capacitor also includes a conductive polymer coating overlying the protective coating. As a result of the present invention, it has been discovered that a capacitor can be formed that can have a relatively low leakage current, dissipation factor, and equivalents series resistance.

Claims

1. A solid electrolytic capacitor comprising:

an anode that contains a valve-action metal;

a dielectric film overlying said anode;

a protective coating overlying said dielectric film, wherein said protective coating contains a relatively insulative, resinous material; and

a conductive polymer coating overlying said protective coating.

2. A solid electrolytic capacitor as defined in claim 1, wherein said resinous material is selected from the group consisting of polyurethane, polystyrene, esters of unsaturated or saturated fatty acids, and combinations thereof.

3. A solid electrolytic capacitor as defined in claim 1, wherein said resinous material contains esters of unsaturated or saturated fatty acids or derivatives thereof.

4. A solid electrolytic capacitor as defined in claim 1, wherein said resinous material contains a drying oil or derivatives thereof.

5. A solid electrolytic capacitor as defined in claim 4, wherein said drying oil is selected from the group consisting of olive oil, linseed oil, tung oil, castor oil, soybean oil, shellac, and derivatives thereof.

6. A solid electrolytic capacitor as defined in claim 1, wherein said resinous material contains shellac or derivatives thereof.

7. A solid electrolytic capacitor as defined in claim 1, wherein said valve-action metal is tantalum or niobium.

8. A solid electrolytic capacitor as defined in claim 1, wherein said conductive polymer is selected from the group consisting of polypyrroles, polythiophenes, polyanilines, polyacetylenes, poly-p-phenylenes, and derivatives thereof.

9. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has a normalized leakage current of less than about 0.1 μ

A/μ

F*V, where μ

A is the measured leakage current of the capacitor in microamps and μ

F*V is the product of the capacitance and the rated voltage of the capacitor.

10. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has a normalized leakage current of less than about 0.01 μ

A/μ

F*V, where μ

A is the measured leakage current of the capacitor in microamps and μ

F*V is the product of the capacitance and the rated voltage of the capacitor.

11. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has a dissipation factor of less than about 10%.

12. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has a dissipation factor of less than about 5%.

13. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has a equivalent series resistance of less than about 1000 milliohms.

14. A solid electrolytic capacitor as defined in claim 1, wherein the capacitor has an equivalent series resistance of less than about 500 milliohms.

15. A solid electrolytic capacitor as defined in claim 1, wherein the relatively insulative, resinous material has a resistivity greater than about 1×

10¹⁰ ohms-cm.

16. A solid electrolytic capacitor comprising:

an anode that contains a valve-action metal;

a dielectric film overlying said anode;

a protective coating overlying said dielectric film, wherein said protective coating contains esters of unsaturated or saturated fatty acids; and

a conductive polymer coating overlying said protective coating.

17. A solid electrolytic capacitor as defined in claim 16, wherein said protective coating includes at least one drying oil or derivatives thereof.

18. A solid electrolytic capacitor as defined in claim 16, wherein said drying oil is selected from the group consisting of olive oil, linseed oil, tung oil, castor oil, soybean oil, shellac, and derivatives thereof.

19. A solid electrolytic capacitor as defined in claim 16, wherein said protective coating contains shellac or derivatives thereof.

20. A solid electrolytic capacitor as defined in claim 16, wherein said valve-action metal is tantalum or niobium.

21. A solid electrolytic capacitor as defined in claim 16, wherein said conductive polymer is selected from the group consisting of polypyrroles, polythiophenes, polyanilines, polyacetylenes, poly-p-phenylenes, and derivatives thereof.

22. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a normalized leakage current of less than about 0.1 μ

A/μ

F*V, where μ

A is the measured leakage current of the capacitor in microamps and μ

F*V is the product of the capacitance and the rated voltage of the capacitor.

23. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a normalized leakage current of less than about 0.01 μ

A/μ

F*V, where μ

A is the measured leakage current of the capacitor in microamps and μ

F*V is the product of the capacitance and the rated voltage of the capacitor.

24. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a dissipation factor of less than about 10%.

25. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a dissipation factor of less than about 5%.

26. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a equivalent series resistance of less than about 1000 milliohms.

27. A solid electrolytic capacitor as defined in claim 16, wherein the capacitor has a equivalent series resistance of less than about 500 milliohms.

28. A solid electrolytic capacitor comprising:

an anode that contains a valve-action metal;

a dielectric film overlying said anode;

a protective coating overlying said dielectric film, wherein said protective coating contains shellac or derivatives thereof; and

a conductive polymer coating overlying said protective coating.