Anode element, method of manufacturing the same, and solid electrolytic capacitor

Abstract

An anode element of a solid electrolytic capacitor and a method of fabricating the anode element are improved, so that the step of manufacturing the solid electrolytic capacitor is simplified, reliability is improved, and a withstand voltage of the solid electrolytic capacitor is increased. An anode element including a metal and a coating layer formed on a surface thereof, the coating layer being composed of a hydrated oxide shown as MOx.yH2O in chemical formula (1), where M represents a valve metal and x and y represent an integer or a decimal fraction from 1 to 6, a hydroxide shown as M(OH)n in chemical formula (2), where M represents a valve metal and n represents an integer or a decimal fraction from 1 to 6, or a composite thereof, a method of manufacturing the anode element, and a solid electrolytic capacitor employing the anode element are provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing one embodiment of a single-plate-type solid electrolytic capacitor in the present invention.

FIG. 2 is a diagram showing one embodiment of a wound-type solid electrolytic capacitor in the present invention.

FIG. 3 is a graph showing relation between a withstand voltage of a solid electrolytic capacitor and a Vt withstand voltage of a barrier-type anodic oxide film.

FIG. 4 is a graph showing a result of measurement of a withstand voltage of a solid electrolytic capacitor, obtained by applying a constant current to the solid electrolytic capacitor employing as an anode element a metal not having a coating layer formed on its surface.

FIG. 5 is a graph showing a leakage current in liquid and a leakage current of the solid electrolytic capacitor.

FIG. 6 is a graph showing relation between a rated voltage of a general solid electrolytic capacitor (conventional product) and a withstand voltage of the general solid electrolytic capacitor.

FIG. 7 is a graph showing relation of a withstand voltage of a solid electrolytic capacitor according to a product of the present invention and a withstand voltage of a solid electrolytic capacitor according to a conventional product, with a dielectric layer thickness.

Claims

1. An anode element comprising: a metal; anda coating layer formed on a surface of the metal;said coating layer being composed ofa hydrated oxide shown as MOx.yH2O  in chemical formula (1)

2. The anode element according to claim 1, wherein an anodic oxide film is formed between said surface of said metal and said coating layer.

3. A method of manufacturing the anode element according to claim 1, comprising the step of forming the coating layer on the surface of the metal by heating the metal in deionized water or in an aqueous solution containing a hydration accelerator agent or by subjecting the metal to deionized water steaming treatment.

4. A method of manufacturing the anode element according to claim 1, comprising the step of forming the coating layer on the surface of the metal by subjecting the metal to cathodic electrolysis in an aqueous solution containing phosphoric acid or a salt thereof, or silicic acid or a salt thereof.

5. A method of manufacturing the anode element according to claim 1, comprising the step of forming the coating layer on the surface of the metal by treating the metal with a solution containing an acid selected from the group consisting of phosphoric acid, oxalic acid and chronic acid and a metal selected from the group consisting of zinc, titanium and potassium or a salt thereof.

6. The method of manufacturing the anode element according to claim 3, wherein said coating layer is subjected to dehydration treatment.

7. The method of manufacturing the anode element according to claim 4, wherein said coating layer is subjected to dehydration treatment.

8. The method of manufacturing the anode element according to claim 5, wherein said coating layer is subjected to dehydration treatment.

9. A solid electrolytic capacitor comprising a solid electrolyte layer stacked on an anode element including a metal and a coating layer formed on a surface of the metal, said coating layer being composed ofa hydrated oxide shown as MOx.yH2O  in chemical formula (1)

10. The solid electrolytic capacitor according to claim 9, wherein an anodic oxide film is formed between said surface of said metal and said coating layer.

11. The solid electrolytic capacitor according to claim 10, wherein a part of the anodic oxide film or entire anodic oxide film is subjected to hydration treatment.

12. A method of manufacturing a solid electrolytic capacitor, comprising the step of stacking a solid electrolyte layer on the anode element obtained with the method of manufacturing the anode element according to claim 3.

13. A method of manufacturing a solid electrolytic capacitor, comprising the step of stacking a solid electrolyte layer on the anode element obtained with the method of manufacturing the anode element according to claim 4.

14. A method of manufacturing a solid electrolytic capacitor, comprising the step of stacking a solid electrolyte layer on the anode element obtained with the method of manufacturing the anode element according to claim 5.

15. The solid electrolytic capacitor according to claim 9, wherein said coating layer having a thickness of at least 2 nm per solid electrolytic capacitor rated voltage 1V is formed, anda measurement value of a Vt withstand voltage of said coating layer in accordance with EIAJ RC-2364A is equal to or smaller than twice as large as the solid electrolytic capacitor rated voltage.

16. The solid electrolytic capacitor according to claim 9, wherein a cutting surface of the anode element or a coating layer defective portion is repaired with the coating layer.

17. The solid electrolytic capacitor according to claim 9, wherein a rated voltage is set to at least 20V.