JP3314480B2 - Solid electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor used for various electronic devices.

[0002]

2. Description of the Related Art In a conventional solid electrolytic capacitor of this type, when a solid electrolyte layer is formed on an electrode body having an anodized film serving as a dielectric formed on the surface of a valve metal, the following method is used. I was going. For example, when manganese dioxide is formed as a solid electrolyte, the manganese dioxide layer has been formed by immersing the electrode body in an aqueous solution of manganese nitrate, causing manganese nitrate to adhere, and then thermally decomposing at a high temperature. When a 7,7,8,8-tetracyanoquinodimethane complex salt (hereinafter, referred to as a TCNQ salt) of an organic semiconductor is formed as a solid electrolyte, the electrode body is immersed in a TCNQ salt melted at a high temperature, and The electrode body was cooled and solidified to form a TCNQ salt as a solid electrolyte. When a conductive polymer layer is formed as a solid electrolyte, the electrode body is immersed in a polymer solution containing an electrolyte and a monomer, and an oxidation reaction of the monomer is caused electrochemically to form a polymer layer. That is, a so-called electrolytic polymerization method has been used.

As described above, when any of the solid electrolyte layers is formed, the electrode body is once immersed in a liquid material which is a raw material for forming the solid electrolyte. Therefore, it is necessary to clearly separate the anode lead portion and the cathode lead portion.

In this case, conventionally, FIG. 3 and FIG.
As shown in FIG. 4 , the etched aluminum etched foil 1
In order to clearly separate the anode extraction portion and the cathode extraction portion from each other, an insulating band portion 2 for bisecting the aluminum etched foil 1 is provided at a predetermined portion of the surface of the aluminum etched foil 1; An anodized film 3 serving as a dielectric is formed on the surface of the aluminum foil 1 by chemical conversion, and one surface of the aluminum-etched foil 1 divided by the insulating band 2 is immersed in an aqueous solution of manganese nitrate. A solid electrolyte layer 4 of manganese dioxide is formed by repeating this process, and then a cathode extraction conductor layer 5 composed of a graphite layer and a conductive metal paste layer is formed on the solid electrolyte layer 4 to form a solid electrolytic capacitor element 6. I was

[0005]

In the conventional solid electrolytic capacitor described above, in FIGS. 3 and 4 , the aluminum-etched foil 1 is separated from the aluminum-etched foil 1 in order to clearly separate the anode lead and the cathode lead. An insulating band portion 2 for bisecting the aluminum-etched foil 1 is provided on a predetermined portion of the surface of
Ri, A Rumietchido one surface of the foil 1 was immersed in aqueous solution of manganese nitrate, thermal decomposition is repeated 10 times to form a solid electrolyte layer 4 of the manganese dioxide if, manganese nitrate to be throw its hat crawl explicitly electrode lead-out portion wicking of aqueous solutions can be controlled more insulator band portion 2, thereby, it becomes possible to clearly separate the anode lead-out portion and a cathode lead-out portion, the cathode lead-out conductive layer on the solid electrolyte layer 4 when forming a 5, as shown in FIGS. 3 and 4, to form a cathode lead-out conductor layer 5 to the top of the insulator band portion 2, a solid electrolyte layer
There is a possibility that the material constituting the cathode lead-out conductor layer 5 penetrates into the discontinuous portion of the boundary surface between the insulator band portion 4 and the insulator band portion 2 and directly contacts the anodic oxide film 3 serving as a dielectric.

In this case, if a defective portion exists in the anodic oxide film 3 serving as a dielectric or a defective portion occurs in the anodic oxide film 3 during a later process or when a solid electrolytic capacitor is used, the anodic oxidation The material constituting the cathode extraction conductor layer 5 having no ability to repair the coating 3 is in direct contact with the defective portion to increase the leakage current or to short-circuit, thereby reducing the withstand voltage characteristic and the leakage current characteristic of the solid electrolytic capacitor. Have a big impact,
This has been one of the major causes for increasing the failure rate and failure rate.

The present invention solves the above-mentioned conventional problems, in which a defective portion is present in an anodic oxide film serving as a dielectric or a defective portion is formed in a anodic oxide film in a later step or when a solid electrolytic capacitor is used. It is an object of the present invention to provide a solid electrolytic capacitor in which the material constituting the cathode extraction conductor layer does not directly contact the defective portion.

[0008]

In order to achieve the above object, a solid electrolytic capacitor according to the present invention comprises a plate-shaped valve-acting metal having an anodic oxide film serving as a dielectric on the surface thereof, and a surface of the valve-acting metal. An insulating band portion provided on a predetermined portion of the valve metal and bisecting the valve action metal, a solid electrolyte layer is formed on one surface of the valve action metal bisected by the insulator band portion, and the insulator Forming another insulating layer on the boundary between the band and the solid electrolyte layer, and further covering a part of the other insulating layer or preventing it from coming into contact with the other insulating layer; Is formed on the solid electrolyte layer.

[0009]

According to the above arrangement, when the cathode lead-out conductor layer is formed, the material constituting the cathode lead-out conductor layer penetrates into the discontinuous portion at the boundary between the solid electrolyte layer and the insulator band. Thus, there is no possibility of direct contact with the anodic oxide film serving as a dielectric.

As a result, even if a defective portion is formed in the anodic oxide film in a later step or when a solid electrolytic capacitor is used, the material constituting the cathode extraction conductor layer having no ability to repair the anodic oxide film in the defective portion is obtained. Since direct contact is eliminated, leakage current is not increased as in the past, and short-circuiting does not greatly affect the withstand voltage characteristics and leakage current characteristics of solid electrolytic capacitors, so that the failure rate and failure rate do not increase. As a result, a solid electrolytic capacitor having a small leakage current and a stable product breakdown voltage can be obtained.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 As shown in FIGS. 1 and 2, an aluminum foil cut into a strip having a width of 3 mm and a length of 5 mm is electrochemically etched in an aqueous solution of hydrochloric acid or the like to increase the surface area. An aluminum-etched foil 21 serving as a valve action metal was used, and a 1.5 mm-wide adhesive tape made of polyimide as a base material was attached to a portion of a length of 3 mm from an end surface of the aluminum-etched foil 21 in a strip shape. The etched aluminum foil 21 was divided into two parts by providing the insulating strip 22 and then anodized film 23 serving as a dielectric was formed by forming the surface of the aluminum etched foil 21 at 70V.

Thereafter, one surface of the aluminum-etched foil 21, which is divided into two parts by the insulator band portion 22, which is to be a cathode lead-out portion, is immersed in a low-concentration manganese nitrate aqueous solution.
The pyrolysis performed for 0 minutes was repeated 10 times to form a solid electrolyte layer 24 of manganese dioxide.

Thereafter, another 1 mm-wide epoxy resin having a width of about 1 mm is formed on the boundary between the insulator band 22 made of a polyimide-based adhesive tape having a width of 1.5 mm and the solid electrolyte layer 24 of manganese dioxide. Forming an insulator layer 25,
Thereafter, a cathode extraction conductor layer 26 composed of a graphite layer and a silver paint layer was formed on the solid electrolyte layer 24 so as to cover a part of the other insulator layer 25, thereby forming a solid electrolytic capacitor element 27. .

(Comparative Example 1) A cathode extraction conductor layer 5 composed of a graphite layer and a silver paint layer was replaced with an insulating band composed of a 1.5 mm wide adhesive tape made of polyimide as shown in FIGS. 3 and 4 . The solid electrolytic capacitor element 6 was formed by forming the entire cathode lead-out portion of the aluminum-etched foil 1 from the portion 2, that is, on the solid electrolyte layer 4.

( Example 2 ) Width 1.5 mm using polyimide as a base material in Example 1
Example 1 except that the insulating band portion 22 made of an adhesive tape was changed to an insulating band portion made of an epoxy resin coating, and the solid electrolyte layer 24 made of manganese dioxide was changed to a conductive polymer made of polypyrrole. The solid electrolytic capacitor element 27 was configured in the same manner as described above.

[0017] (Comparative Example 2) graphite layer, the cathode lead-out conductor layer 5 to FIG. 3 made of silver paint layer, an aluminum etched foil from the top of the insulator strip portion 2 made of an epoxy resin coating, as shown in FIG. 4 The solid electrolytic capacitor element 6 was formed by forming the whole of the cathode lead portion of No. 1 on the solid electrolyte layer 4.

Table 1 shows Examples 1 and 2 of the present invention,
Leakage current characteristics for each of Comparative Examples 1 and 2 ,
It shows the results of measuring the product breakdown voltage characteristics and the leakage current defect rate.

[0019]

[Table 1]

[0020] As is clear from (Table 1), the real of the present invention
Examples 1 and 2 are comparative examples 1 and 2 showing a conventional configuration.
2 , the leakage current can be reduced, the product breakdown voltage can be improved, and the leakage current defect rate can be improved.

In the above embodiment, the case where the aluminum-etched foil 21 is used as the valve action metal having the flat plate structure has been described. However, the valve action metal other than aluminum is selected from tantalum, titanium, niobium and the like. Even when a foil or a plate material capable of forming an anodic oxide film is used, the same operation and effect as those of the above embodiment can be obtained.

In the above embodiment, when the cathode extraction conductor layer 26 made of a graphite layer and a silver paint layer is formed on the solid electrolyte layer 24 , another insulator layer 25 is used.
Has been described so as to cover a part of the solid electrolyte layer 24. However, even when the cathode extraction conductor layer 26 is formed on the solid electrolyte layer 24 so as not to contact another insulator layer 25, The same operation and effect as in the example are achieved.

[0023]

As described above, the solid electrolytic capacitor of the present invention is provided with an insulator band on a predetermined portion of the surface of a plate-shaped valve metal having an anodic oxide film serving as a dielectric on the surface thereof. A solid electrolyte layer is formed on one surface of the valve action metal bisected by the material band, and another insulator layer is formed on the boundary between the insulator band and the solid electrolyte layer; In the case where the cathode extraction conductor layer is formed because the cathode extraction conductor layer is formed on the solid electrolyte layer so as to cover a part of the insulator layer or not to contact another insulator layer, In addition, there is no danger that the material forming the cathode lead-out conductor layer will penetrate into the discontinuous portion of the boundary surface between the solid electrolyte layer and the insulator band portion and directly contact the anodic oxide film serving as a dielectric.

Thus, even if a defect exists in the anodic oxide film serving as a dielectric or a defect occurs in the anodic oxide film in a later step or when a solid electrolytic capacitor is used, the anodic oxide film is formed on the defective portion. Since the material constituting the cathode extraction conductor layer without the ability to repair does not come into direct contact, the leakage current is increased or short-circuited as in the past, and the withstand voltage and leakage current characteristics of the solid electrolytic capacitor are greatly affected. , The failure rate and the failure rate are not increased, and as a result, a solid electrolytic capacitor having a small leakage current and a stable product breakdown voltage can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic configuration of a flat solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA ′ in FIG.

FIG. 3 is a perspective view showing a basic configuration of a flat type solid electrolytic capacitor showing a conventional configuration.

FIG. 4 is a sectional view taken along line CC ′ in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Aluminum-etched foil 22 Insulator strip 23 Anodized film 24 Solid electrolyte layer 25 Separate insulator layer 26 Cathode lead conductor layer

Claims (2)

(57) [Claims] 1. A valve metal having a flat plate structure having an anodic oxide film serving as a dielectric formed on a surface thereof, and an insulator band provided at a predetermined portion of the surface of the valve metal and bisecting the valve metal. Having a solid electrolyte layer on one surface of the valve action metal bisected by the insulator band, and forming another insulator layer on a boundary between the insulator band and the solid electrolyte layer A solid electrolytic capacitor in which a cathode extraction conductor layer is formed on the solid electrolyte layer so as to cover a part of the other insulator layer or not to contact the other insulator layer. 2. The cathode extraction conductor layer comprises a graphite layer.
The solid electrolytic capacitor according to claim 1, comprising: