Capacitor and method for manufacturing the same
A method for manufacturing a capacitor that enables a capacitor having a high degree of conductivity and minimal leakage current to be obtained with a high level of productivity. A method for manufacturing a capacitor ( 10 ) according to the present invention includes an electrolytic oxidation step of forming a dielectric layer ( 12 ) by electrolytically oxidizing the surface of an anode ( 11 ) composed of a valve metal, a cathode positioning step of positioning a cathode ( 13 ) composed of a conductor in an opposing arrangement on the surface of the dielectric layer ( 12 ), a solid electrolyte formation step of forming a solid electrolyte layer ( 14 ) between the dielectric layer ( 12 ) and the cathode ( 13 ) using a conductive polymer solution containing a π-conjugated conductive polymer and a polyanion, and an application step of performing a treatment in which a direct current voltage is applied between the anode ( 11 ) and the cathode ( 13 ).
1. A capacitor comprising
an anode made of a valve metal,
a dielectric layer formed by oxidizing a surface of said anode,
a cathode made of a conductor, and
a solid electrolyte layer that is formed between said dielectric layer and said cathode and comprises a π-conjugated conductive polymer and a polyanion, wherein
a treatment is performed in which a direct current voltage is applied between said anode and said cathode,
said direct current voltage during said treatment is not less than 20% of a formation voltage of said dielectric, and
said capacitor exhibits a leakage current I of less than 0.03CV, provided that I represents the current after application of the rated voltage at room temperature for 2 minutes, C represents the capacitance at room temperature, and V represents the rated voltage value for the solid electrolytic capacitor.
2. The capacitor according to claim 1 , wherein said solid electrolyte layer further comprises a resin component besides said π-conjugated conductive polymer and said polyanion.
3. The capacitor according to claim 2 , wherein said direct current voltage during said treatment is not less than 50% of a rated voltage of an obtained capacitor.
4. The capacitor according to claim 2 , wherein said direct current voltage during said treatment is from 50% to 180% of a rated voltage of an obtained capacitor.
5. The capacitor according to claim 2 , wherein said solid electrolyte layer is formed from a conductive polymer solution comprising π-conjugated conductive polymer and a polyanion.
6. The capacitor according to claim 5 , wherein said conductive polymer solution comprises a (co)polymer composed of any one or two compounds selected from the group consisting of polypyrrole, polythiophene, poly(N-methylpyrrole), poly(3-methylthiophene), poly(-methoxythiophene) and poly(3,4-ethylenedioxythiophene); and polystyrene sulfonic acid.
7. The capacitor according to claim 5 , wherein said conductive polymer solution comprises poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid.
8. The capacitor according to claim 1 , wherein said direct current voltage during said treatment is not less than 50% of a rated voltage of an obtained capacitor.
9. The capacitor according to claim 1 , wherein said direct current voltage during said treatment is from 50% to 180% of a rated voltage of an obtained capacitor.
10. The capacitor according to claim 1 , wherein said solid electrolyte layer is formed from a conductive polymer solution comprising a π-conjugated conductive polymer and a polyanion.
11. The capacitor according to claim 10 , wherein said conductive polymer solution comprises a (co)polymer composed of any one or two compounds selected from the group consisting of polypyrrole, polythiophene, poly(N-methylpyrrole), poly(3-methylthiophene), poly(3-methoxythiophene) and poly(3,4-ethylenedioxythiophene); and polystyrene sulfonic acid.
12. The capacitor according to claim 10 , wherein said conductive polymer solution comprises poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid.
13. A method of manufacturing a capacitor, comprising:
an electrolytic oxidation step of forming a dielectric layer by electrolytically oxidizing a surface of an anode made of a valve metal,
a cathode positioning step of positioning a cathode made of a conductor in an opposing arrangement on a surface of said dielectric layer,
a solid electrolyte formation step of forming a solid electrolyte layer between said dielectric layer and said cathode using a conductive polymer solution comprising a π-conjugated conductive polymer and a polyanion, and
an application step of performing a treatment in which a direct current voltage is applied between said anode and said cathode, wherein
said current voltage during said application step is not less than 20% of a formation voltage of said dielectric, and said capacitor exhibits a leakage current I of less than 0.03 CV, provided that I represents the current after application of the rated voltage at room temperature for 2 minutes, C represents the capacitance at room temperature, and V represents the rated voltage value for the solid electrolytic capacitor.
14. The method of manufacturing a capacitor according to claim 13 , wherein said direct current voltage in said application step is not less than 50% of a rated voltage of an obtained capacitor.
15. The method of manufacturing a capacitor according to claim 14 , wherein said application step is performed under an atmosphere of not less than 35° C.
16. The method of manufacturing a capacitor according to claim 15 , wherein said application step is performed within a solution comprising an organic solvent and a salt.
17. The method of manufacturing a capacitor according to claim 14 , wherein said application step is performed within a solution comprising an organic solvent and a salt.
18. The method of manufacturing a capacitor according to claim 13 , wherein said application step is performed under an atmosphere of not less than 35° C.
19. The method of manufacturing a capacitor according to claim 18 , wherein said application step is performed within a solution comprising an organic solvent and a salt.
20. The method of manufacturing a capacitor according to claim 13 , wherein said application step is performed within a solution comprising an organic solvent and a salt.
21. The method of manufacturing a capacitor according to claim 13 , wherein said direct current voltage during said application step is from 50% to 180% of a rated voltage of an obtained capacitor.