JPH09246106A - Solid capacitor and formation of conductive functional polymer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a conductive functional polymer film for a solid capacitor such that electrolytic oxidation polymerization easily proceeds even when the thickness of an anodized aluminum film is increased, and a solid capacitor having a conductive functional polymer film formed by the same method. SOLUTION: After an anodized film 2 is formed on a roughened surface of an aluminum foil 1 by formation processing, the aluminum foil is immersed into a boric acid aqueous solution of 1 to 5wt.% (% by weight) and cleaned therewith. Then, a silane thin film layer 4 of γ-glycidoxypropyltrimethoxysilane or octadecyl-triethoxysilane is formed on the anodized film. After that, a conductive functional polymer film layer 5 is formed on the anodized film 2 by electrolytic oxidation polymerization in an acetonitrile solution containing pyrrole and ammonium borodisalicylate, or dodecyebenzenesulfonic acid.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor having a conductive functional polymer film formed on an anodized film formed on the surface of an aluminum foil and using the conductive functional polymer as an electrolyte, and its conductive function. The present invention relates to a method for forming a polymer film.

[0002]

2. Description of the Related Art A solid electrolytic capacitor in which a conductive functional polymer film is formed on an anodized film formed on the surface of an aluminum foil and the conductive functional polymer is used as an electrolyte is used in conventional electrolytic capacitors. It is known as a solid capacitor having low impedance and low equivalent series resistance because it has a very small specific resistance value as compared with existing electrolytes (driving electrolyte, manganese dioxide, etc.).

Conventionally, in the above-mentioned solid-state capacitor, as a method of forming a conductive functional polymer film formed on an anodic oxide film, two types have been proposed, a method by chemical oxidative polymerization and a method by electric field oxidative polymerization.

Of the above-mentioned two types of methods for forming the conductive functional polymer film layer on the aluminum anodic oxide film, the method by electric field oxidative polymerization is effective, but the conductive functional polymer is formed on the aluminum anodic oxide film. The composition of the electrolytic oxidation polymerization solution for forming the film layer is, for example, by dissolving pyrrole in an acetonitrile solvent, and as the electrolyte, a boron compound (ammonium borodi salicylate, borodi citric acid, etc.) or a sulfur compound (dodecylbenzene). Most effective is a solution of sulfonic acid, tetraethylammonium paratoluenesulfonic acid, etc.).

[0005]

However, even when the conductive functional polymer film layer is formed by using the above-mentioned electrolytic oxidation polymerization liquid composition, the leakage current value becomes large when the rated voltage of the solid capacitor becomes high. There is. This drawback is due to poor adhesion at the interface between the aluminum anodic oxide coating and the conductive functional polymer, or variations in the film thickness, density, uniformity, etc., of the conductive functional polymer film layer. Conceivable. This is because the electrolytic oxidation polymerization reaction becomes more difficult and the reaction does not proceed smoothly as the thickness of the aluminum oxide film increases.

The present invention has been made in view of the above points, and even if the thickness of the aluminum anodic oxide coating is increased,
An object of the present invention is to provide a method for forming a conductive functional polymer film of a solid capacitor in which an electrolytic oxidative polymerization reaction easily proceeds and a solid capacitor having the conductive functional polymer film formed by this method.

[0007]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present application is to form an anodized film on the surface of a roughened aluminum foil by chemical conversion treatment,
The surface of an aluminum foil in a solid capacitor using as an electrolyte a conductive functional polymer film formed by electrolytic oxidation polymerization in an acetonitrile solution containing pyrrole and ammonium borodi salicylate or dodecylbenzene sulfonic acid on the anodic oxide film. A silane thin film layer of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane was formed on the anodic oxide film formed on, and a conductive functional polymer film serving as an electrolyte was formed on the silane thin film layer. It is characterized by

Further, according to the invention described in claim 2, after the anodic oxide film is formed on the surface of the roughened aluminum foil by chemical conversion treatment, a predetermined portion is masked with an insulating material, and the masking is performed. In the acetonitrile solution containing pyrrole and ammonium borodisalicylate or dodecylbenzene sulfonic acid in the non-applied portion, a solid-state capacitor having a conductive functional polymer film formed on the anodic oxide film by electrolytic oxidation polymerization is used. In the method for forming a conductive functional polymer film, after forming an anodized film on the surface of an aluminum foil, the aluminum foil is immersed and washed in a 1-5 wt% (weight%) aqueous boric acid solution, and then the anode is formed. After forming a silane thin film layer of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane on the oxide film, Wherein the over emissions thin layer to form the conductive features polymer film.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a manufacturing process of a solid capacitor of the present invention. As shown in FIG. 4A, an aluminum foil 1 whose surface is roughened by etching is prepared. A voltage of 100 V was applied to the aluminum foil 1 in an electrolytic aqueous solution containing three components of boric acid / ammonium borate / ammonium phosphate, and an aluminum anode was applied to the surface of the aluminum foil 1 as shown in FIG. The oxide film 2 is formed.

After a predetermined portion of the aluminum anodic oxide film 2 of the aluminum foil 1 is masked with an insulating material 3, the aluminum foil 1 has a concentration of 1 to 5 wt.% (3
Immerse in an aqueous boric acid solution having a wt% of optimum of 40 to 70 ° C. (optimal of 60 ° C.) for 30 seconds to 5 minutes (optimally 1.5 minutes) and wash. Then, it is immersed in an alcohol solution (methanol or ethanol) of 0.5 to 5 wt% (1 wt% is optimal) of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane for 1 hour, and at 105 ° C. for 10 minutes, for example. After drying and curing, a silane thin film layer 4 of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane is formed on the aluminum anodic oxide film 2 as shown in FIG.

Subsequently, as shown in FIG. 1D, a conductive functional polymer film layer 5 is formed on the silane thin film layer 4 by electrolytic oxidation polymerization. The conductive functional polymer film layer 5 is formed by dissolving pyrrole in an acetonitrile solvent and using a boron compound (ammonium borodi salicylate, borodi citric acid, etc.) or a sulfur compound (dodecylbenzene sulfonic acid) as an electrolyte. , Tetraethylammonium paratoluenesulfonic acid, etc.) in a solution in which electrolytic oxidation polymerization is performed.

Subsequently, a graphite layer 6 and a silver paste layer 7 are sequentially formed on the conductive functional polymer film layer 5 by a known method to form a solid capacitor element.

As described above, the aluminum anodic oxide coating 2
A method of forming a silane thin film layer 4 of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane on the surface of which is dipped and washed with an aqueous solution of boric acid, and then forming a conductive functional polymer film layer 5 thereon. By adopting, the surface of the aluminum anodic oxide film 2 and the silane thin film layer 4 are brought into close contact with each other, and the conductive functional polymer film layer 5 can be easily formed on the silane thin film layer 4.

Table 1 shows 100 V in an electrolytic aqueous solution containing three components of boric acid, ammonium borate and ammonium phosphate.
And a conventional example in which a conductive polymer film layer is formed on an aluminum chemical conversion foil having an aluminum anodic oxide film formed thereon, and the aluminum chemical conversion foil is dipped and washed with an aqueous boric acid solution, and then γ-
Appearance of conductive functional polymer with the present embodiment in which a silane thin film layer of glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane is formed, and a conductive functional polymer film layer is formed on the silane thin film layer. A comparative example of the non-defective rate is shown below. The area for forming the conductive functional polymer film layer is 2
It is 0 mm × 20 mm.

[0015]

[Table 1] As shown in Table 1 above, in comparison with the conventional example, the appearance non-defective rate of the conductive polymer film layer is significantly improved in the present embodiment.

FIG. 2 shows the solid-state capacitor of the present invention having the structure shown in FIG. 1 (e) and a conventional solid-state capacitor {FIG. 1 (e).
FIG. 7 is a diagram showing a comparative example of the leakage current value of the device without the thin film layer 4 in FIG. As is clear from FIG. 2, the leakage current value of the solid-state capacitor of the present invention is significantly smaller than that of the conventional capacitor. In FIG. 2,
The number of capacitors used in the test is 15 in each of the present invention and the conventional example.

[0017]

As described above, according to the present invention, the following effects can be obtained. (1) According to the invention of claim 1, a silane thin film layer of γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane is formed on the anodic oxide film, and the silane thin film layer is electrically conductive. Since the functional functional polymer film is formed, it is possible to provide a solid-state capacitor having a small leakage current.

(2) According to the invention described in claim 2, after forming the anodic oxide film, it is immersed and washed in an aqueous solution of boric acid, and then γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane. By forming a silane thin film layer of, and then forming a conductive functional polymer film on the silane thin film layer, the surface of the anodic oxide film and the thin film layer adhere to each other, and there are few defects on the thin film layer. A conductive functional polymer film can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a solid capacitor of the present invention.

FIG. 2 is a diagram showing a comparative example of leakage current values of a solid capacitor of the present invention and a conventional solid capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum foil 2 Aluminum anodic oxide film 3 Insulating material 4 Thin film layer of silane 5 Conductive functional polymer film layer 6 Graphite layer 7 Silver paste layer

Claims (2)

[Claims] 1. An acetonitrile solution containing pyrrole and ammonium borodisalicylate or dodecylbenzenesulfonic acid on the surface of a roughened aluminum foil by chemical conversion treatment to form an anodized film. Then, in a solid capacitor using a conductive functional polymer film formed by electrolytic oxidation polymerization as an electrolyte, γ-glycidoxypropyltrimethoxysilane or octadecyltriethoxysilane is formed on the anodized film formed on the surface of the aluminum foil. And a conductive functional polymer film serving as the electrolyte is formed on the silane thin film layer. 2. A roughened aluminum foil surface is subjected to a chemical conversion treatment to form an anodized film, and then a predetermined portion is masked with an insulating material, and the portion not masked is treated with pyrrole. Method for forming a conductive functional polymer film of a solid capacitor in which a conductive functional polymer film is formed on the anodic oxide film by electrolytic oxidation polymerization in an acetonitrile solution containing ammonium borodisalicylate or dodecylbenzenesulfonic acid In the above, after forming an anodized film on the surface of the aluminum foil, the aluminum foil is dipped and washed in a 1-5 wt% (weight%) boric acid aqueous solution, and then γ-glycid is formed on the anodized film. Forming a silane thin film layer of oxypropyltrimethoxysilane or octadecyltriethoxysilane,
After that, the conductive functional polymer film is formed on the silane thin film layer, and the conductive functional polymer film for a solid capacitor is formed.