JPH03139816A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To completely insulate by doping compound liquid solute, and to prevent a solid electrolytic capacitor from short-circuiting and an LC defect, by forming a chemical polymer film on an oxide film, then applying a reverse voltage in compound liquid, and applying a positive voltage thereto. CONSTITUTION:After a chemical polymer film made of conductive polymer is formed on an oxide film, a winding element is formed. Then, the element is dipped in compound liquid of ammonium adipate as solute, a reverse current of 0.1mA is applied for 10 min, a part in direct contact with the defect of the polymer film is selectively dedoped, and a positive voltage is subsequently applied to recompound the defective part. Simultaneously, adipic acid is selectively doped only at the selectively dedoped part to provide a complete insulator. Thus, since a completely insulating layer is formed between the metal and a negative layer, improper breakdown strength, a short-circuiting, a LC defect, etc., can be completely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer membrane as a solid electrolyte.

(Prior art) In recent years, solid electrolytic capacitors that meet the demand for smaller size and higher performance have been developed as disclosed in Japanese Patent Application Laid-open No. 60-244017 or Japanese Patent Application Laid-open No. 60-244017.
There is one disclosed in Publication No. 3-181308.

The technology disclosed in these publications is that an anode body obtained by chemically converting a valve metal with a roughened surface to form an oxide film is used as an anode, immersed in an electrolytic solution and energized to form an oxide film on the oxide film. It uses an electrolytic polymer membrane as a solid electrolyte,
Since the oxide film is an insulator, effective current conduction with the cathode is not carried out, and current concentrates in defective parts of the oxide film or in areas close to the cathode, resulting in a uniform electrolytic polymer film as a solid electrolyte. was extremely efficient.

Therefore, a chemical oxidation polymerization method is taken in which the anode body is immersed in, for example, a virol solution, and then immersed in an acid quenching agent solution to form a chemically polymerized film on the anode body in advance.
Electrolytic oxidation polymerization is carried out in an electrolytic solution using this chemically polymerized membrane as an anode to effectively form an electrolytically polymerized membrane on the chemically polymerized membrane.

However, if there is a defect in the oxide film, the conductive chemically polymerized film comes into direct contact with the defect during chemical oxidation polymerization, causing short-circuit failure. Therefore, re-formation is generally performed after the formation of a chemically polymerized film, but as mentioned above, the conductive chemically polymerized film is in direct contact with the defective areas, resulting in very poor chemical formation, resulting in poor voltage resistance and shot defects. , it could not be a drastic measure against LC defects.

(Problems to be Solved by the Invention) The solid electrolytic capacitor obtained by the above method is worthy of attention as it meets the demand for smaller size and higher performance, but if there is a defect in the oxide film, short circuit failure, L
Since C defects occur, there has been a problem in that the yield rate becomes extremely low during the manufacturing process.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor that can prevent short-circuit defects, LC defects, etc. of solid electrolytic capacitors using a conductive polymer membrane as a solid electrolyte. This is the purpose.

[Structure of the Invention] (Means for Solving the Eight Problems) The method for manufacturing a solid electrolytic capacitor of the present invention involves forming a chemically polymerized film by chemical oxidative polymerization on an oxide film formed on a valve metal, and then In a method for manufacturing a solid electrolytic capacitor in which an electrolytic polymer film is formed on a polymer film by electrolytic oxidation polymerization, after forming a chemical polymer film on the oxide film, a reverse voltage is applied in a chemical solution, and then a positive voltage is applied. It is characterized by the fact that it is applied.

(Function) According to the above configuration, when the defective part of the oxide film is in contact with the conductive chemically polymerized film, a reverse current selectively flows to the defective part of the oxide film, so that the part of the chemically polymerized film is Only the part that is in contact with the defect is dedoped, and is completely insulated by doping with the chemical solution solute in the subsequent chemical formation, so even in this excellent electrolytic oxidation polymerization, this insulating chemical No electrolytic polymerization or film is formed on the polymer film, and an insulating layer is completely formed between the metal that is the FIJ electrode and the cathode layer.

(Example) An embodiment of the present invention will be described below.

That is, an RA anode foil anode lead wire made of, for example, high-purity aluminum, whose surface area has been expanded by etching and an oxide film formed on the surface through a chemical conversion process, is attached, and then this anode foil is coated with virol, thiophene, or After being immersed in a Ran/ethanol aqueous solution, it is further immersed in an ammonium persulfate aqueous solution containing tetraethylammonium para-toluenesulfonate as a supporting electrolyte to perform chemical oxidative polymerization to form a chemically polymerized film made of conductive polymer on the oxide film. After forming, it is wound to form a wound body. next,
This wound body is immersed in a chemical solution containing ammonium adipate or the like as a solute, and a reverse current of 0.1yyLA is applied for 10 minutes to selectively dedope the portions that are in direct contact with film defects in the chemically polymerized film. Then, by applying a positive current, the defective parts of the film are reformed, and at the same time, only the selectively dedoped parts are selectively doped with adipic acid to become a complete insulator. next,
Most of the polymers were immersed in an electrolytic oxidative polymerization solution containing a supporting electrolyte and monomers such as virol, thiophene, and furan, and subjected to electrolytic oxidative polymerization. An electrolytic polymer film made of conductive polymer is produced on a conductive chemical polymer film.

Next, a cathode layer is provided on colloidal carbon by dipping and applying silver paste, a cathode lead is attached to this cathode layer, and finally, an exterior is applied.

According to the manufacturing method of a solid electrolytic capacitor having the above structure, the chemical polymer film can only be formed in a very limited area where the defective part of the oxide film and the chemical polymer film, which is a conductive polymer, are in direct contact after chemical oxidation polymerization. When dedoping paratoluenesulfonic acid, etc., which gives S conductivity, and then re-forming the oxide film, doping only the dedoped areas with adipic acid, etc., which gives insulation to the chemically polymerized film. Therefore, the reconstitution of defective parts of the oxide film is carried out smoothly, and furthermore, a conductive electrolytic polymer film is not formed on the insulating chemical polymer film during electrolytic oxidation polymerization, and the electrolytic oxidation polymerization solution Since the dopant such as para-toluene sulfonic acid in the insulating film is not doped into the insulating polymer film, which has already been doped with adipic acid, for example, an oxide film formed by re-chemically forming a defective part. Even if processes such as low breakdown voltage are taken into account, an insulating layer is completely formed between the metal anode and the cathode layer, so breakdown voltage defects, short circuit defects, LC defects, etc. can be completely prevented. .

Next, a solid electrolytic capacitor obtained by the present invention,
A comparison of the characteristics of solid electrolytic capacitors obtained using conventional examples will be described.

The numerical table shows the rating 1 according to Example A and Conventional Example B described below.
This figure shows the initial characteristics of a 0V-3μF solid electrolytic capacitor.

In addition, the values in the table excluding short-circuit defects are for sample 1.
The average value is 00, and the numbers in parentheses indicate variations.

Example A (1) Chemical oxidative polymerization conditions After immersing a chemically treated aluminum anode foil in a virol/ethanol solution for 5 minutes, 0.05 mol/tetraethylammonium toluenesulfonate was added as a supporting electrolyte.
j! Immersed in 0.1m0I/1 ammonium persulfate aqueous solution containing 5 minutes.

(2) Capacitor element structure and winding shape (3) Electrolytic oxidative polymerization conditions Immersed in an electrolytic solution consisting of acetonitrile containing virol monomer 1 mol/41 and sodium paratoluenesulfonate 1 mol/j as a supporting electrolyte, and subjected to constant current oxidative polymerization. (1TrLA/ai, 30 minutes).

(4) Reverse current application conditions After applying a reverse current (0.1 mA/j, 10 minutes) in a 0.15 M ammonium adipate aqueous solution, reconstitution (positive current application) is performed immediately.

Conventional Example Day (1) Chemical oxidation polymerization conditions Same as Example A (2) Capacitor element structure Same as Example A (3) Electrolytic oxidation polymerization conditions Same as Example A (4) Reverse 1! No current is applied Table 1 As is clear from the above table, the leakage current characteristics of Example A are significantly improved compared to those of Conventional Example B, and a significant improvement effect on short-circuit defects is observed. It will be done.

Although the above embodiments have been described using aluminum foil as the anode foil, the present invention can also be applied to valve metal foils such as tantalum foil or niobium foil.

In addition, although the element structure was explained using a wound structure in the above embodiment, it is also possible to use a device in which these valve metal foils are made into a flat plate without being wound, or powders made of these valve metal foils are sintered. Of course, it can be applied to a compacted and sintered body.

[Effects of the Invention] According to the present invention, only the polymer film in the defective part of the oxide film is insulated, so that the anode metal and the cathode layer are completely insulated with almost no capacity loss due to insulation. Therefore, it is possible to obtain a manufacturing method for solid electrolytic capacitors that greatly contributes to the improvement of initial characteristics and at the same time can significantly improve the product yield due to the effect of greatly reducing short-circuit defects.

Special permission Out wish Man Marcon Electronics Co., Ltd. Nippon Power ~ Lit Co., Ltd.

Claims (1)

[Claims] (1) In a method for manufacturing a solid electrolytic capacitor, a chemically polymerized film is formed by chemical oxidative polymerization on an oxide film formed on a valve metal, and then an electrolytic polymerized film is formed on this chemically polymerized film by electrolytic oxidative polymerization. A method for manufacturing a solid electrolytic capacitor, which comprises forming a chemically polymerized film on a film, applying a reverse voltage to a capacitor element in a chemical solution, and then applying a positive voltage.