JPS63181310A - Reformation treatment of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a solid electrolytic capacitor, particularly to a reconversion treatment method.

[Conventional technology]

Solid electrolytic capacitors are made by anodizing a metal that has a valve action and forming a solid electrolyte semiconductor layer on the anodized layer.The solid electrolyte uses manganese dioxide, an inorganic semiconductor, and TCNQ salt, an organic semiconductor. The one used is well known. However, by using polymer thin films of heterocyclic compounds such as pyrrole, furan, and thiophene, which have higher conductivity than manganese dioxide or TCNQ salt, numerous advantages can be obtained in terms of the properties and manufacturing of solid electrolytic capacitors. (For example, Japanese Patent Application No. 60-003)
No. 324).

The present invention relates to a method for manufacturing a solid electrolytic capacitor using a polymer thin film of the above-mentioned heterocyclic compound as a semiconductor layer.

[Problem that the invention seeks to solve]

Generally, after the semiconductor layer is formed, re-formation is performed because the withstand voltage of the oxide film decreases. In the case of solid electrolytic capacitors that use a polymer thin film, if there is a defect in the oxide film during electrolytic oxidation polymerization, the electrolytic oxidation polymerization liquid enters the defective part, creating a thin oxide film in that part. It is presumed that spots will occur, resulting in poor withstand voltage. In particular, in electrolytic oxidation polymerization, polymerization is carried out at low temperatures and with a constant current to control the polymer film thickness, so the voltage applied to the oxide film is usually higher than the anodization voltage, which tends to cause breakdown voltage problems4. If you correct the film thickness to be thicker,
Defects caused by the above causes can be eliminated. In this case, unlike the case of forming an oxide film on aluminum or the like, since the chemical formation is carried out with a polymer thin film formed, it is particularly important to prevent the polymer thin film from deteriorating.

In view of the above circumstances, an object of the present invention is to provide an optimal method for reconversion treatment of a solid electrolytic capacitor using a polymer thin film as a semiconductor layer.

[Means for solving problems]

In the present invention, after forming a polymer thin film by electrolytic oxidation polymerization and replacing the electrolytic oxidation polymerization solution with a chemical solution,
It is designed to re-form at temperatures below 0°C.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the following example, the rating is 6.3V.

Targeting a 4.7 μF capacitor, aluminum was used as the anode body, aluminum etched foil with a roughened surface was cut into 5 mm x 3 Q'm, and first constant voltage chemical conversion was performed at 20 V in an adipic acid chemical solution. Form an anodic oxide film on the foil surface.

Next, the portion of the aluminum etched foil that will become the anode lead is protected with a resist member, and a polypyrrole film is formed on the other portions by electrolytic oxidation polymerization. This formation is acetonitrile II! as a solvent, 0.05 mo of virol
In an electrolytic solution containing approximately 0.02 mol (6.0 g) of ammonium borodisalicylate as a supporting salt, a current of 10 mA/ad was applied at -43°C.
It was run for 0 minutes.

In the reconversion treatment, first, as a pretreatment, the material is sufficiently washed in acetonitrile, then heated and dried, and then vacuum impregnated in an adipic acid-based chemical solution. As a result, the electrolytic oxidation polymerization liquid is completely replaced. The sample that has undergone the above pretreatment is subjected to a chemical conversion treatment for 5 minutes in an adipic acid-based chemical solution. At this time, 50 samples were subjected to chemical conversion for 5 minutes at each temperature of 20°C, 50°C, 60°C, and 80°C.

Next, the reconstituted foil is washed with pure water and dried, and a graphite layer and a silver paste layer are sequentially formed using a dipping method, and then a cathode lead is drawn out using greasy paste to form a capacitor element. Figure 2 is a cross-sectional view, and 1 is an aluminum etched foil whose tip is an anode lead. The capacitor component part has an aluminum oxide film 2. Polypyrrole film 3. Graphite layer 4. Consists of silver paste layer 5, silver paste 6
The cathode lead 7 is connected by. 8 is a resist layer.

As a characteristic change due to reconstitution conditions, tan δ at 10 KHz was measured, and the results shown in FIG. 1 were obtained.

As shown in Figure 1, when the re-formation temperature is below 50℃, 5%
If the temperature exceeds 50°C, an increase in tan δ will be observed. At temperatures below 30°C, tan δ can be approximately 3%. Note that the permissible value of tan δ is generally considered to be about 10%. The deterioration of tan δ is considered to be due to an increase in the resistance of the polymer thin film, which is a semiconductor layer. Polymer thin films go through a heat treatment process such as graphite/silver paste after re-forming, so it is possible that they may deteriorate due to this, but this sample was treated at a relatively low temperature, and the samples at each temperature (50 (e) underwent the same treatment, so the difference in characteristics shown in FIG. 1 above can be attributed to the temperature treatment for re-formation.

Although the reconstitution liquid in the experimental data presented was an adipic acid-based liquid, similar results were obtained with commonly used liquids such as boric acid-based and phosphoric acid-based liquids.

Furthermore, it has been experimentally found that if the replacement with the chemical solution is not complete after the electrolytic oxidation polymerization, the re-forming time must be increased.

〔Effect of the invention〕

As explained above, the temperature is set at 50°C as a re-forming condition for a solid electrolytic capacitor using a polymer thin film as a semiconductor layer.
By limiting the tan δ of the capacitor (@
10 KHz) was able to be suppressed to 10% or less. As a result, for applications where conventionally film capacitors were mostly used as high frequency capacitors,
The solid electrolytic capacitor according to the present invention can be fully used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing capacitor characteristics when the formation temperature is changed in one embodiment of the present invention, and FIG. 2 is a sectional view of a capacitor element. 1-Aluminum etched foil, 2-Aluminum oxide film, 3-Polypyrrole film, 4-Graphite layer, 5-1
1 paste layer, 6-i paste, 7 cathode lead, 8 resist layer. Patent applicant Nippon Tsushin Kogyo Co., Ltd. Agent Patent attorney Akihiko Sato 2nd cause

Claims (1)

[Claims] In a solid electrolytic capacitor having a polymer thin film of a heterocyclic compound as a semiconductor layer, a metal body having a valve action is anodized, and a semiconductor layer is formed on the anodic oxide film by electrolytic oxidation polymerization. . A reconversion treatment method for a solid electrolytic capacitor, which comprises replacing an electrolytic oxidation polymerization solution with a chemical conversion solution, and then performing reconversion at a temperature of 50° C. or lower.