Tantalum capacitor with polymer cathode
View Patent ↗An improved capacitor and a method for forming an improved capacitor is detailed. The method comprises forming a tantalum anode from a tantalum powder with a powder charge of no more than 40,000 μC/g; forming a dielectric on the anode by anodization at a formation voltage of no more than 100 V; and forming a conductive polymeric cathode on the dielectric wherein the capacitor has a breakdown voltage higher than the formation voltage.
1. A method for forming a capacitor comprising:
forming a tantalum anode from a tantalum powder with a powder charge of no more than 40,000 μC/g;
forming a dielectric on said anode by anodization at a formation voltage of no more than 100 V;
forming a conductive polymeric cathode on said dielectric; and
wherein said capacitor has a breakdown voltage higher than said formation voltage.
2. The method for forming a capacitor of claim 1 wherein said tantalum powder has a powder charge of at least 5,000 μC/g.
3. The method for forming a capacitor of claim 2 wherein said tantalum powder has a powder charge of at least 10,000 μC/g to no more than 25,000 μC/g.
4. The method for forming a capacitor of claim 1 wherein said formation voltage is at least 25 Volts.
5. The method for forming a capacitor of claim 1 wherein said formation voltage is at least 40 volts.
6. The method for forming a capacitor of claim 1 wherein said conductive polymeric cathode comprises polythiophene.
7. The method for forming a capacitor of claim 6 wherein said conductive polymer is poly-3,4-polyethylene dioxythiophene.
8. The method for forming a capacitor of claim 1 wherein said forming of said conductive polymeric cathode is by dipping in a polymer slurry.
9. The method for forming a capacitor of claim 8 wherein said polymer slurry comprises poly-3,4-polyethylene dioxythiophene.
10. The method for forming a capacitor of claim 1 wherein said capacitor has a resistance of at least 1,000Ω after treatment at a voltage exceeding said breakdown voltage.
11. The method for forming a capacitor of claim 10 wherein said capacitor has a resistance of at least 100,000Ω after treatment at a voltage exceeding said breakdown voltage.
12. The method for forming a capacitor of claim 1 further comprising treating said capacitor to moist atmosphere.
13. The method for forming a capacitor of claim 12 wherein said moist atmosphere is at a temperature of at least 0° C. to no more than 100° C. with at least 50% relative humidity to no more than 90% relative humidity.
14. The method for forming a capacitor of claim 12 comprising treating with said moist atmosphere to achieve up to a maximum amount of water absorbed.
15. The method for forming a capacitor of claim 14 comprising treating with said moist atmosphere to achieve a moisture content of 20-90% of said maximum amount of water absorbed.
16. The method for forming a capacitor of claim 1 wherein said capacitor has a maximum rated voltage of at least 60% to no more than 90% of said formation voltage.
17. The method for forming a capacitor of claim 1 wherein said forming of said tantalum anode further comprises sintering.
18. The method for forming a capacitor of claim 1 wherein said sintering further comprises at least one of decarbonizing or deoxygenating.