JPH0541337A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To make small the value of an ESR in a solid electrolytic capacitor. CONSTITUTION:In a method of forming a semiconductor layer 3 of a solid electrolytic capacitor which is formed by laminating in order a dielectric oxide film layer 2, the layer 3 and a conductor layer 4, a polyaniline solution, which is obtained by dedoping a polyaniline polymertized at a low temperature by a chemical oxidation method and is soluble to an organic solvent, and a high- molecular solution having a sulfone group to work as a dopant are alternately made to soak in the upper part of the layer 2. Thereby, the insoluble polyaniline semiconductor layer 3 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor having excellent high frequency characteristics and reliability.

[0002]

2. Description of the Related Art As shown in FIG. 3, a solid electrolytic capacitor element has a dielectric oxide film layer 2 formed on the surface of an anode substrate 1 made of a valve metal such as aluminum or tantalum, and a semiconductor such as manganese dioxide. In order to form a layer, the dielectric oxide film layer 2 is dipped in a manganese nitrate aqueous solution and then thermally decomposed at a temperature of 250 to 350 (° C.) to form a manganese dioxide semiconductor layer 3 ′.
Then, there is one in which a conductor layer 4 such as a silver paste layer is formed in order to reduce the contact resistance. In addition, a tetracyanoquinodimethane salt that is an organic semiconductor layer (hereinafter abbreviated as TCNQ salt)
There is a method in which the surface of the dielectric oxide film layer 2 is impregnated with the melted material and the semiconductor layer 3 ′ is formed by rapid cooling. Further, there is another one in which a polymer layer of a heterocyclic compound such as pyrrole, thiophane, or furan is formed on the dielectric oxide film 2 by electrolytic oxidation polymerization to form the semiconductor layer 3 '.

[0003]

However, in the above-mentioned first conventional example, since the high temperature treatment of 250 to 350 (° C.) is performed when forming the semiconductor layer of manganese dioxide, not only the operation is complicated, but also the dielectric material is used. There is a drawback that the oxide film is easily damaged, resulting in a large leakage current. In addition, in the second conventional example, the cost of TCNQ salt is high, and there is a step of impregnating the molten TCNQ salt on the dielectric oxide film layer to form a semiconductor layer and quenching the TCNQ salt. There is a drawback that it is very difficult to control the temperature in order to prevent aging (becomes a semiconductor). Also in the third conventional example, since the semiconductor layer made of the polymer of the heterocyclic compound is formed on the dielectric oxide film layer by electrolytic oxidation, it is difficult to form the dielectric oxide film layer without damaging it. Is. Therefore, in order to avoid damage to the dielectric oxide film layer, a semiconductor layer can be formed on the anode substrate by electrolytic oxidation polymerization before forming the oxide film, and then a dielectric oxide film layer can be formed by a chemical reaction. When a chemical reaction is caused through the layer, the physical properties of the semiconductor layer are changed and the resistance value becomes high. As described above, it is difficult to form the semiconductor layer with a good yield without damaging the dielectric oxide film layer by any means. Therefore, the present invention aims to solve the above-mentioned problems associated with the conventional example.

[0004]

SOLUTION: A solid electrolysis in which a dielectric oxide film layer, a polyaniline semiconductor layer, and a conductor layer are sequentially laminated on the surface of an anode substrate made of a metal having a valve action. In the method for forming the polyaniline semiconductor layer of a capacitor, a polyaniline solution soluble in an organic solvent obtained by low-temperature polymerization by a chemical oxidation method and dedoping, and a polymer solution having a sulfone group acting as a dopant Are alternately permeated onto the dielectric oxide film layer to form an insoluble polyaniline semiconductor layer.

[0005]

The semiconductor layer is formed on the dielectric layer by low temperature polymerization by the chemical polymerization method, and can be formed in a stable state without being damaged by the heat treatment.

[0006]

EXAMPLES The present invention will now be described in more detail by way of examples in contrast with the main parts of the products shown in FIGS. 1 and 2. Aluminum (other tantalum and alloys using these as substrates, etc., as the anode substrate 1 have a valve action. (Any metal that can be used can be used), and this is subjected to a chemical conversion treatment in an aqueous ammonium adipate solution, and the dielectric oxide layer 2
(A layer made of an oxide of the anode base metal itself having a valve action is preferable, and the means for providing the oxide layer does not prevent the conventional method) formed 26 (μF / cm ² ) aluminum A small piece of etching foil (hereinafter called chemical foil).
Weld the anode terminal 5 to 3 × 0.6 (cm). In order to obtain soluble polyaniline, ammonium persulfate 6.85 (g) (a ferric chloride or the like can be used) is dissolved as an oxidant in 3N sulfuric acid aqueous solution 200 (ml) and cooled to -7 (° C). After that, 1.4 (g) of aniline was gradually added dropwise and polymerized for 90 minutes to synthesize insoluble polyaniline. After that, the polymerized product was washed with distilled water to give an alkaline aqueous solution of 28%.
24 mL of ammonia water (sodium hydroxide solution may be used)
It was immersed for a time, washed with distilled water and dried under reduced pressure. This was dissolved in dimethylformamide (or N-methyl-2-pyrrolito) which is a solvent for soluble polyaniline to obtain a polyaniline solution. Next, the above chemical conversion foil was alternated with a polyaniline solution and a dimethylformamide solution of polymer poly-2-acrylamido-2-methylpropanesulfonic acid (which has a sulfonic acid group) which functions as a dopant. By repeatedly dipping and drying under reduced pressure, the insoluble polyaniline semiconductor layer 3 is formed on the dielectric oxide film layer 2 already formed. And by immersing the formed foil in a silver paste solution,
A conductor layer 4 of silver paste was formed on the formed insoluble polyaniline semiconductor layer 3, and a cathode terminal 6 was fixed with silver paste, which was sealed with resin to obtain a solid electrolytic capacitor. The characteristics of this capacitor are as follows: electrostatic capacity 2.11 (μF), dielectric loss tangent (tan δ) 0.015, frequency 1
Equivalent series resistance (ESR) at 00 (KHz) 0.13
(Ω) and leakage current was 0.01 (μA). In this way, the polyaniline semiconductor layer 4 of the solid electrolytic capacitor element of the present invention comprises a polyaniline solution soluble in an organic solvent, obtained by dedoping, and a polymer solution having a sulfonic acid group acting as a dopant. Can be formed by alternately permeating the dielectric oxide layer 3 on the dielectric oxide layer 3.

[0007]

Industrial Applicability The method for producing the semiconductor layer of the solid electrolytic capacitor in which the dielectric oxide film layer, the semiconductor layer and the conductor layer are sequentially laminated on the surface of the anode substrate made of a valve metal, The polyaniline semiconductor layer obtained by alternately permeating the polyaniline solution and the polymer solution having a sulfonic acid group on the coating layer can provide a solid electrolytic capacitor having a small ESR value in a high frequency region.

[Brief description of drawings]

FIG. 1 is a schematic enlarged sectional view of a capacitor obtained according to the present invention.

FIG. 2 is a schematic plan view of the same.

FIG. 3 is an enlarged cross-sectional view of a conventional capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode substrate 2 Dielectric oxide film layer 3 Polyaniline semiconductor layer 4 Dielectric layer

Claims (1)

[Claims] 1. A polyaniline semiconductor layer of a solid electrolytic capacitor in which a dielectric oxide film layer, a polyaniline semiconductor layer, and a conductor layer are sequentially laminated on the surface of an anode substrate made of a metal having a valve action. In the method, the organic oxide-soluble polyaniline solution obtained by low-temperature polymerization by a chemical oxidation method and dedoping, and a polymer solution having a sulfone group acting as a dopant are alternately formed. A method for producing a solid electrolytic capacitor, which comprises permeating the layer above to form an insoluble polyaniline semiconductor layer.