JPH06188144A - Manufacture of capacitor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a small non-polarized capacitor used for an electronic component and having large capacity and high-frequency characteristics. CONSTITUTION:After a porous conductive surface is coated with a thin film of polyamic-acid by electrodeposition, the thin film is put in some other steps and dehydrated by heating to form a polyimide film. The electrodeposition and dehydrating steps are repeated so that the polyimide thin film is completed. A polypyrrole film through chemical oxidation polymerization and a polypyrrole film through electrolytic polymerization are laminated sequentially so that a conductive layer as a counter electrode is formed on the polyimide film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a capacitor used in electronic circuits such as electric and electronic equipment.

[0002]

2. Description of the Related Art With the miniaturization and weight reduction of electric and electronic devices, there is an increasing demand for miniaturization and high performance of electronic components. Among them, various attempts have been made to develop a small-capacity, large-capacity capacitor excellent in high frequency characteristics.

A film capacitor having excellent high frequency characteristics is not suitable for practical use because its shape becomes large and its cost becomes high when a large capacity is obtained.

On the other hand, the aluminum electrolytic capacitor known as a large-capacity capacitor is inferior in high frequency characteristics. However, recently, an aluminum solid electrolytic capacitor using a conductive polymer as a solid electrolyte has appeared as a capacitor having excellent high frequency characteristics.

[0005]

The aluminum solid electrolytic capacitor using a conductive polymer as the above-mentioned conventional solid electrolyte is small in size and wound to obtain a large capacity, and the stress causes cracks in the dielectric oxide film. There was a problem that it was easy to enter, and there was a problem that the positive and negative directions could not be mistaken at the time of mounting due to the polarity unique to electrolytic capacitors.

The present invention solves the above-mentioned conventional problems, and provides a method for manufacturing a non-polarized capacitor having both characteristics of a film capacitor and an aluminum electrolytic capacitor, a small size, a large capacity, and excellent high frequency characteristics. The purpose is to provide.

[0007]

In order to achieve this object, a method of manufacturing a capacitor according to the present invention comprises adding a poor solvent for a polyamic acid to a solution containing a polyamic acid salt on the surface of a porous conductor. After electrodeposition as an electrodeposition liquid to form a polyamic acid thin film, treatment is performed, and then heat dehydration is performed to form a polyimide film, and electrodeposition and imidization are repeated again to form a more complete polyimide film. . Further, a conductor layer serving as a counter electrode is formed on the surface of this polyimide coating.

[0008]

According to the present invention, after a poor solvent for polyamic acid is added to a solution containing polyamic acid on the surface of a porous conductor to perform electrodeposition as an electrodeposition liquid to form a thin film of polyamic acid. , The treatment is performed to remove the incomplete portion of the polyamic acid thin film formation, and then heat dehydration is performed to form the polyimide coating, and the electrodeposition and imidization are repeated again to repair the incomplete portion of the polyimide coating. As a result, a good polyimide coating with very few defects is formed on the porous conductor surface. Further, by forming a conductive layer serving as a counter electrode on the surface of the polyimide coating, a non-polar capacitor having a small size, a large capacity and excellent high frequency characteristics can be obtained.

[0009]

EXAMPLES (Examples) Examples of the present invention will be described below.

After the aluminum etching foil roughened to about 50 times was cut into 5 mm × 20 mm, an aluminum lead was joined by ultrasonic welding to obtain a metal electrode.

On the other hand, 3.3 parts by weight of p-phenylenediamine was dissolved in 90 parts by weight of N, N-dimethylformamide, 6.7 parts by weight of pyromellitic dianhydride was added, and the mixture was reacted at room temperature for 10 hours to obtain a polyamic acid solution. . To this polyamic acid solution, 1.8 parts by weight of triethylamine was added and reacted at room temperature for 1 hour to obtain a polyamic acid salt solution in which half of the carboxyl groups of the polyamic acid were neutralized. This solution 60
40 parts by weight of methanol was added to parts by weight to prepare an electrodeposition liquid.

This electrodeposition solution is placed in a stainless steel container, and the roughened metal electrode is immersed as an anode, and the stainless steel container is used as a cathode. Electrodeposition is carried out by continuously applying the electrodeposition voltage of 50 V for 30 minutes, and the metal electrode A thin film of polyamic acid was formed on the surface.

Subsequently, the metal electrode having a polyamic acid thin film formed on the surface thereof is immersed in N, N-dimethylformamide for 3 minutes to dissolve and remove a portion where the polyamic acid thin film is not completely formed. A polyimide coating was formed on the surface of the roughened metal electrode by heat dehydration at 250 ° C. for 30 minutes.

Then, in order to repair the incomplete portion of the polyimide coating, the metal electrode having the polyimide coating formed on the surface is used as an anode, and the stainless container containing the electrodeposition solution is used as a cathode to perform electrodeposition again. A thin film of polyamic acid was formed on the incomplete portion of the coating, and dehydrated by heating to form a polyimide coating more completely, which was used as an element.

This device was prepared by adding 2 mol / liter of pyrrole /
After immersing in ethanol solution for 5 minutes, further immersing in 0.5 mol / liter ammonium persulfate aqueous solution for 5 minutes,
A polypyrrole film was formed by chemical oxidative polymerization. Subsequently, this device was immersed in an acetonitrile solution containing 1 mol / liter of pyrrole and 1 mol / liter of tetraethylammonium p-toluenesulfonate as a supporting electrolyte, and the polypyrrole film formed by chemical oxidative polymerization was used as an anode, and electropolymerization was performed with an external electrode. At a current density of 1 mA / cm ²
The operation was performed for 0 minutes to form a polypyrrole film by electrolytic polymerization.

By dipping this element in colloidal carbon,
A silver paste was applied to form a conductive coating film, a counter electrode was taken out from a part of the conductive coating film, and an exterior was coated with an epoxy resin to complete a capacitor.

Comparative Example A capacitor was completed in the same manner as in the example, except that the step of performing the treatment before imidizing the polyamic acid thin film was omitted.

The characteristics of the capacitors obtained in the above examples and comparative examples are shown in (Table 1).

[0019]

[Table 1]

As is clear from this (Table 1), the capacitor obtained in this embodiment has a dielectric loss, a leakage current,
In terms of equivalent series resistance, excellent characteristics are obtained as compared with the capacitor obtained in the comparative example.

Although N, N-dimethylformamide was used as the treatment liquid in the above-mentioned Examples, similar results were obtained with N-methyl-2-pyrrolidinone.

[0022]

As described above, in the method for producing a capacitor according to the present invention, a poor solvent for polyamic acid is added to a solution containing a polyamic acid salt on the surface of a porous conductor to perform electrodeposition as an electrodeposition solution. After forming a thin film of polyamic acid, treatment is performed to remove the incomplete portion of the thin film of polyamic acid, and then heat dehydration is performed to form a polyimide film, and electrodeposition and imidization are repeated again to form a polyimide film. By repairing the incomplete portion of the polyimide film, a good polyimide coating with very few defects is formed on the porous conductor surface.

Further, a conductive layer serving as a counter electrode is formed on the surface of the polyimide coating by sequentially laminating a polypyrrole film formed by chemical oxidative polymerization and a polypyrrole film formed by electrolytic polymerization. It is possible to realize a non-polarized capacitor having excellent high frequency characteristics.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Takemoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hideo Yamamoto, 2470 Handa, Shibukawa City, Gunma Prefecture, Japan Central Research Center (72) Inventor, Isao 2470, Handa, Shibukawa City, Gunma Japan Central Research Center

Claims (5)

[Claims] 1. A thin polyamic acid film is formed on a surface of a porous conductor by adding a poor solvent for polyamic acid to a solution containing a polyamic acid salt to form a thin film of polyamic acid. A capacitor formed by forming a polyimide coating on the surface of a conductor made porous by heat dehydration and imidization of a thin film of acid, and further forming a counter electrode conductor layer on the surface of this polyimide coating. , Before imidizing the polyamic acid thin film,
A method of manufacturing a capacitor, which comprises subjecting a capacitor to a treatment. 2. The method for producing a capacitor according to claim 1, wherein the treatment is a method of immersing in the treatment liquid for a certain period of time. 3. The method for producing a capacitor according to claim 2, wherein the treatment liquid is a solvent that dissolves the polyamic acid. 4. The conductive layer serving as the counter electrode is formed by sequentially stacking a conductive polymer film formed by chemical oxidative polymerization and a conductive polymer film formed by electrolytic polymerization. 2. A method for manufacturing a capacitor according to any one of 1. 5. The method for manufacturing a capacitor according to claim 4, wherein the conductive polymer film is polypyrrole.