Method for making a capacitor

Abstract

A method for making a capacitor includes: forming an anode that has a main body and a lead; mounting securely an insulator washer on the lead such that the insulator washer is spaced apart from an upper end of the main body of the anode, the insulator washer dividing the lead of the anode into an upper end portion and a lower end portion; forming a dielectric layer on the main body and the lead of the anode such that the dielectric layer has a main portion covering the main body, and a lead portion covering the lower end portion of the lead of the anode; and forming a conductive layer on the dielectric layer such that the conductive layer covers the main portion of the dielectric layer and the lead portion of the dielectric layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of this invention, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are schematic sectional views to illustrate consecutive steps of a conventional method for making a capacitor;

FIG. 3 is a schematic sectional view of a capacitor formed by the preferred embodiment of a method according to this invention; and

FIGS. 4 to 6 are schematic sectional views to illustrate consecutive steps of the preferred embodiment of the method for making the capacitor of FIG. 3.

Claims

1. A method for making a capacitor, comprising: (a) forming an anode that has a main body and a lead, the main body having an upper end, the lead extending outwardly and being reduced in cross-section from the upper end of the main body;(b) mounting securely an insulator washer on the Read such that the insulator washer is spaced apart from the upper end of the main body of the anode, the insulator washer having a lower surface facing the upper end of the main body of the anode, and an upper surface opposite to the lower surface, and dividing the lead of the anode into an upper end portion that extends upwardly from the upper surface of the insulator washer, and a lower end portion that extends downwardly from the lower surface of the insulator washer to the upper end of the main body;(c) forming a dielectric layer on an outer surface of the main body and an outer surface of the lower end portion of the lead of the anode such What the dielectric layer has a main portion covering the outer surface of the main body, and a lead portion covering at least a portion of the outer surface of the lower end portion of the lead of the anode;(d) forming a conductive layer on the dielectric layer such that the conductive layer covers an outer surface of the main portion of the dielectric layer and at least a portion of an outer surface of the lead portion of the dielectric layer; and(e) forming a cathode on the conductive layer.

2. The method of claim 1, wherein formation of the dielectric layer in step (c) is conducted by anodizing techniques.

3. The method of claim 2, wherein the anode is placed in a liquid body of an acid electrolyte in step (c) in such a manner that the surface of the liquid body of the acid electrolyte is above the lower surface of the insulator washer and below the upper surface of the insulator washer.

4. The method of claim 1, wherein the anode is made from a metal selected from the group consisting of tantalum, aluminum, niobium, and titanium.

5. The method of claim 1, wherein formation of the conductive layer in step (d) is conducted by immersing the anode formed is with the dielectric layer in a solution of a conductive polymer, removing the anode formed with the dielectric layer and the conductive layer therefrom, followed by drying a film of the conductive polymer adhered to the dielectric layer.

6. The method of claim 5, wherein the anode formed with the dielectric layer is immersed in the solution of the conductive polymer in such a manner that the surface of the solution of the conductive polymer is substantially flush with the lower surface of the insulator washer.

7. The method of claim 6, wherein the conductive polymer is selected from the group consisting of polythiophenes, polyanilines, and polypyrrole.

8. The method of claim 6, wherein the conductive polymer is poly-3,4-ethylenedioxythiophene.

9. The method of claim 1, wherein the cathode is formed by coating a graphite layer of a graphite paste on the dielectric layer, and a silver layer of a silver paste on the graphite layer.

10. The method of claim 9, further comprising connecting an anode terminal lead to the upper end portion of the lead of the anode, and a cathode terminal lead to the cathode.

11. The method of claim 10, further comprising enclosing an assembly of the anode, the insulator washer, the dielectric layer, the conductive layer, the cathode, a portion of the anode terminal lead, and a portion of the cathode terminal lead using an insulator material.