Solid electrolytic capacitor with enhanced humidity resistance and method for producing the same
An improved capacitor is provided. The capacitor comprises an anode and a functional dielectric on said anode and a conductive layer on the functional dielectric. An anode wire extends from said anode wherein the anode wire has a thickened dielectric layer thereon.
1. A capacitor comprising:
an anode;
a functional dielectric on said anode;
a conductive layer on said functional dielectric;
an anode wire extending from said anode wherein said anode wire has a thickened dielectric region thereon; and
wherein said thickened dielectric region has a thickness of at least 1.1-10.0 times the thickness of said functional dielectric.
2. The capacitor of claim 1 wherein said anode comprises a valve metal or a conductive oxide of a valve metal.
3. The capacitor of claim 2 wherein said anode comprises a valve metal selected from the group consisting of tantalum, aluminum, niobium, titanium, zirconium and hafnium.
4. The capacitor of claim 1 wherein said thickened dielectric region has a thickness of at least 2-8 times the thickness of said functional dielectric.
5. The capacitor of claim 1 wherein said functional dielectric is an oxide of said anode.
6. The capacitor of claim 1 wherein said conductive layer comprises a conductive polymer.
7. The capacitor of claim 6 wherein said conductive polymer is selected from the group consisting of polythiophene, polypyrrole and polyaniline.
8. The capacitor of claim 7 wherein said conductive polymer comprises polymerized 3,4-ethylenedioxythiophene.
9. The capacitor of claim 6 further comprising a blocking polymer on said thickened dielectric.
10. The capacitor of claim 9 wherein said blocking polymer has lower conductivity than said conductive polymer.
11. A method for forming a capacitor comprising:
pressing and sintering a metal to form an anode with an anode wire extending therefrom;
forming a functional dielectric on said anode;
forming a conductive layer on said functional dielectric;
forming a thickened dielectric region on said anode wire; and
cleaning said anode wire prior to said forming said thickened dielectric region.
12. The method for forming a capacitor of claim 11 further comprising applying a blocking polymer on said thickened dielectric.
13. The method for forming a capacitor of claim 12 wherein said blocking polymer has a lower conductivity than said conductive layer.
14. The method for forming a capacitor of claim 11 wherein said anode comprises a valve metal or a conductive oxide of a valve metal.
15. The method for forming a capacitor of claim 14 wherein said anode comprises a valve metal selected from the group consisting of tantalum, aluminum, niobium, titanium, zirconium and hafnium.
16. The method for forming a capacitor of claim 11 wherein said thickened dielectric region has a thickness of at least 1.1-10.0 times the thickness of said functional dielectric.
17. The method for forming a capacitor of claim 16 wherein said thickened dielectric region has a thickness of at least 2-8 times the thickness of said functional dielectric.
18. The method for forming a capacitor of claim 11 wherein said functional dielectric is an oxide of said anode.
19. The method for forming a capacitor of claim 11 wherein said conductive layer comprises a conductive polymer.
20. The method for forming a capacitor of claim 19 wherein said conductive polymer is selected from the group consisting of polythiophene, polypyrrole and polyaniline.
21. The method for forming a capacitor of claim 20 wherein said conductive polymer comprises polymerized 3,4-ethylenedioxythiophene.
22. The method for forming a capacitor of claim 11 further comprising a blocking polymer on said thickened dielectric.
23. The method for forming a capacitor of claim 22 wherein said blocking polymer has lower conductivity than said conductive polymer.
24. A method for forming a capacitor comprising:
pressing and sintering a metal to form an anode with an anode wire extending therefrom;
forming a functional dielectric on said anode;
forming a conductive layer on said functional dielectric; and
forming a thickened dielectric region on said anode wire wherein said forming of said thickened dielectric region comprises applying a forming electrolyte to said anode wire in the presence of applied voltage.
25. A method for forming a capacitor comprising:
pressing and sintering a metal to form an anode with an anode wire extending therefrom;
forming a functional dielectric on said anode;
forming a conductive layer on said functional dielectric; and
forming a thickened dielectric region on said anode wire by applying an applied voltage wherein said applied voltage is higher than a formation voltage.
26. A method for forming a capacitor comprising:
pressing and sintering a metal to form an anode with an anode wire extending therefrom;
forming a functional dielectric on said anode;
forming a conductive layer on said functional dielectric; and
forming a thickened dielectric region on said anode wire by applying a forming electrolyte wherein said applying of said forming electrolyte comprises a conductive nozzle.
27. The method for forming a capacitor of claim 26 wherein said conductive nozzle comprises a metal syringe.
28. The method for forming a capacitor of claim 24 wherein said applying said forming electrolyte comprises pressure.