Solid electrolytic capacitor and method for manufacturing same

1. A solid electrolytic capacitor, comprising:

a solid electrolytic layer; and

a dielectric layer on which the solid electrolytic layer is formed,

wherein the solid electrolytic layer is formed by a process comprising applying and drying a conductive-polymer solution comprising a conductive polymer on the dielectric layer,

the dielectric layer is formed by a process comprising oxidizing a surface of an anode metal,

when particle size distributions of the conductive polymer are measured by a dynamic light-scattering method using a test conductive-polymer solution comprising 1 mass % of the conductive polymer, among one or a plurality of peaks of the particle size distributions, a volume average particle size in the distribution including a peak of the smallest particle size is smaller than 26 nm, and

when a test stacked aluminum electrolytic capacitor comprising the solid electrolytic layer and a test dielectric layer is formed, the test stacked aluminum electrolytic capacitor has a rate of exhibited capacitance of no less than 70%, wherein the solid electrolytic layer is formed by applying and drying the conductive-polymer solution on the test dielectric layer and the test dielectric layer is formed by oxidizing a surface of aluminum having an electrical capacitance of 95 μF/cm 2 .

2. The solid electrolytic capacitor of claim 1 , wherein the conductive-polymer solution includes the conductive polymer in an amount of 9 mass % or less.

3. The solid electrolytic capacitor of claim 2 , wherein the conductive-polymer comprises a repeating unit having a formula (1),

wherein R 1 to R 4 are each independently —H, a straight or branched chain alkyl group having 1 to 24 carbon atoms, a straight or branched chain alkoxy group having 1 to 24 carbon atoms, an acidic group or a salt thereof, a hydroxyl group, a nitro group, —F, —Cl, —Br or —I, provided that at least one of R 1 to R 4 is an acidic group or a salt thereof, the acidic group being either a sulfonic group or a carboxylic group.

4. The solid electrolytic capacitor of claim 1 , wherein the conductive-polymer solution has a surface tension of less than 67 mN/m.

5. The solid electrolytic capacitor of claim 4 , wherein the conductive-polymer comprises a repeating unit having a formula (1),

wherein R 1 to R 4 are each independently —H, a straight or branched chain alkyl group having 1 to 24 carbon atoms, a straight or branched chain alkoxy group having 1 to 24 carbon atoms, an acidic group or a salt thereof, a hydroxyl group, a nitro group, —F, —Cl, —Br or —I, provided that at least one of R 1 to R 4 is an acidic group or a salt thereof, the acidic group being either a sulfonic group or a carboxylic group.

6. The solid electrolytic capacitor of claim 1 , wherein the conductive-polymer solution further comprises a surfactant.

7. The solid electrolytic capacitor of claim 6 , wherein the conductive-polymer comprises a repeating unit having a formula (1),

wherein R 1 to R 4 are each independently —H, a straight or branched chain alkyl group having 1 to 24 carbon atoms, a straight or branched chain alkoxy group having 1 to 24 carbon atoms, an acidic group or a salt thereof, a hydroxyl group, a nitro group, —F, —Cl, —Br or —I, provided that at least one out of R 1 to R 4 is an acidic group or a salt thereof, the acidic group being either a sulfonic group or a carboxylic group.

8. The solid electrolytic capacitor of claim 1 , wherein the conductive-polymer comprises a repeating unit having a formula (1),

wherein R 1 to R 4 are each independently —H, a straight or branched chain alkyl group having 1 to 24 carbon atoms, a straight or branched chain alkoxy group having 1 to 24 carbon atoms, an acidic group or a salt thereof, a hydroxyl group, a nitro group, —F, —Cl, —Br, or —I, provided that at least one of R 1 to R 4 is an acidic group or a salt thereof, the acidic group being either a sulfonic group or a carboxylic group.

9. The solid electrolytic capacitor of claim 1 , wherein the anode metal comprises at least one of tantalum and aluminum.

10. The solid electrolytic capacitor of claim 1 , wherein, when the particle size distributions of the conductive polymer are measured by the dynamic light-scattering method using the test conductive-polymer solution, among one or a plurality of peaks of the particle size distributions, the volume average particle size in the distribution including the peak of the smallest particle size is 5 nm or less.

11. The solid electrolytic capacitor of claim 1 , wherein the conductive-polymer solution includes the conductive polymer in an amount of from 0.1 to 5 mass %.

12. A method for manufacturing a solid electrolytic capacitor, the method comprising:

applying a conductive-polymer solution comprising a conductive polymer to a dielectric layer formed by a process comprising oxidizing a surface of an anode metal; and

drying the conductive-polymer solution such that a solid electrolytic layer is formed on the dielectric layer,

wherein, when particle size distributions of the conductive polymer are measured by a dynamic light-scattering method using a test conductive-polymer solution comprising 1 mass % of the conductive polymer, among one or a plurality of peaks of the particle size distributions, a volume average particle size in the distribution including a peak of the smallest particle size is smaller than 26 nm, and

when a test stacked aluminum electrolytic capacitor comprising the solid electrolytic layer and a test dielectric layer is formed, the test stacked aluminum electrolytic capacitor has a rate of exhibited capacitance of no less than 70%, wherein the solid electrolytic layer is formed by applying and drying the conductive-polymer solution on the test dielectric layer and the test dielectric layer is formed by oxidizing a surface of aluminum having an electrical capacitance of 95 μF/cm 2 .

13. The method of claim 12 , wherein the conductive-polymer solution includes the conductive polymer in an amount of 9 mass % or less.

14. The method of claim 12 , wherein the conductive-polymer solution has a surface tension of less than 67 mN/m.

15. A method for manufacturing a solid electrolytic capacitor, comprising:

applying an organic solvent, or a mixed solvent comprising water and an organic solvent, to a dielectric layer formed by a process comprising oxidizing a surface of an anode metal;

applying a conductive-polymer solution comprising a conductive polymer to the dielectric layer on which the organic solvent or the mixed solvent is applied; and

drying the conductive-polymer solution such that a solid electrolytic layer is formed on the dielectric layer,

wherein, when a test stacked aluminum electrolytic capacitor comprising the solid electrolytic layer and a test dielectric layer is formed, the test stacked aluminum electrolytic capacitor has a rate of exhibited capacitance of no less than 70%, wherein the solid electrolytic layer is formed by applying and drying the conductive-polymer solution on the test dielectric layer and the test dielectric layer is formed by oxidizing a surface of aluminum having an electrical capacitance of 95 μF/cm 2 .

16. The method of claim 15 , wherein, when particle size distributions of the conductive polymer are measured by a dynamic light-scattering method using a test conductive-polymer solution comprising 1 mass % of the conductive polymer, among one or a plurality of peaks of the particle size distributions, a volume average particle size in the distribution including a peak of the smallest particle size is smaller than 26 nm.

17. The method of claim 16 , wherein the conductive-polymer solution includes the conductive polymer in an amount of 9 mass % or less.

18. The method of claim 16 , wherein the conductive-polymer solution has a surface tension of less than 67 mN/m.

19. The method of claim 15 , wherein the conductive-polymer solution includes the conductive polymer in an amount of 9 mass % or less.

20. The method of claim 15 , wherein the conductive-polymer solution has a surface tension of less than 67 mN/m.