JPH118161A - Sold-state electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a solid-state electrolytic capacitor which is protected against cracking caused by external stress in a manufacturing process by a method wherein a film formed of conductive organic polymer composition enhanced in mechanical strength is made to serve as solid-state electrolyte. SOLUTION: A capacitor is equipped with a dielectric oxide film formed on a film forming metal and a conductive organic polymer composition film formed as solid-state electrolyte on the dielectric oxide film. In this case, the conductive organic polymer composition film is, at least, partly set porous. It is preferable that conductive polyaniline composition serves as the above conductive organic polymer composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid electrolytic capacitor using a conductive organic polymer composition, preferably a conductive polyaniline composition as a solid electrolyte, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, electrolytic capacitors known as large-capacity capacitors include an electrolytic solution type and a solid type. Among these, as a solid type capacitor using a solid electrolyte, a method using manganese dioxide or a 7,7,8,8-tetracyanoquinodimethane (TCNQ) complex is known, but the former has a large impedance, The latter has various problems such as poor thermal stability.

[0003] Recent major technical requirements for such electrolytic capacitors include miniaturization, low impedance, high reliability, long life, low cost, and the like accompanying higher frequency of circuits. Conventionally, to meet these requirements, studies have been made to increase the conductivity of the electrolyte of the electrolytic capacitor, and a solid electrolyte using a conductive organic polymer composition has been proposed. Many such conductive organic polymer compositions have been proposed so far, such as polypyrrole, polythiophene, polyfuran, boraniline, and derivatives thereof.

For example, JP-A-63-173313 discloses that a dielectric oxide film is formed on a film-forming metal, and polypyrrole is deposited thereon by chemical oxidation polymerization of pyrrole, and this is used as a conductive layer. Utilizing this conductive layer,
Further, it describes that pyrrole is electrolytically polymerized and a conductive organic polymer composition comprising the polypyrrole is laminated as a solid electrolyte. In addition, Japanese Patent Application Laid-Open No. 1-2532
No. 26 also discloses that a conductive layer made of manganese dioxide is formed on a dielectric film and polypyrrole or polythiophene is laminated thereon by electrolytic polymerization to form a solid electrolyte.

However, according to these methods, it is necessary to laminate polypyrrole or the like by an electrolytic reaction on a dielectric film which is not a conductor, and there is a problem in this point. That is, it is necessary to provide a chemically oxidized polymer film layer or a manganese dioxide layer as a conductive layer to be an electrode for electrolytic polymerization on the dielectric film, and thus it becomes possible to perform electrolytic polymerization only in this way. It is very complicated.

On the other hand, JP-A-3-35516 discloses that
A solution of polyaniline in a undoped state is prepared, this solution is applied on a dielectric film, and dried to form a polyaniline film.Then, the film is brought into contact with a protonic acid solution to convert polyaniline into a protonic acid anion. Has proposed a method of doping. According to this method, as described above, a film made of the conductive organic polymer composition can be easily formed on the dielectric film without having to form an electrode for electrolytic polymerization on the dielectric film. This is advantageous in terms of manufacturing efficiency and cost.

However, the mechanical strength of a film of a conventionally known conductive organic polymer composition, including polyaniline, is not always sufficient. As a result, there is a problem that cracks or the like are generated and the capacitor characteristics are deteriorated. For example, as an exterior resin, an epoxy resin is generally widely used, and the epoxy resin expands and contracts with a rise in temperature during molding, and a decrease in temperature. by this,
If defects such as cracks occur in the film of the conductive organic polymer composition formed on the device, the electric resistance increases, thus deteriorating the characteristics as a capacitor.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems in a conventional solid electrolytic capacitor using a conductive organic polymer composition, preferably a conductive polyaniline composition as a solid electrolyte. A solid electrolyte having a conductive organic polymer composition film having improved mechanical strength as a solid electrolyte.Therefore, in a manufacturing process thereof, cracks and the like do not occur due to external stress, and a solid having improved characteristics. An object of the present invention is to provide an electrolytic capacitor and a method for manufacturing the same.

[0009]

According to the present invention, a dielectric oxide film formed on a film-forming metal and a conductive organic polymer composition formed as a solid electrolyte on the dielectric oxide film are provided. A solid electrolytic capacitor having a membrane and
A solid electrolytic capacitor is provided, wherein at least a part of the film of the conductive organic polymer composition is porous.

Particularly, a preferred embodiment of the solid electrolytic capacitor according to the present invention is any of the following. That is, a first preferred solid electrolytic capacitor according to the present invention comprises a dielectric oxide film formed on a film-forming metal and a film of a conductive organic polymer composition formed as a solid electrolyte on the dielectric oxide film. In the solid electrolytic capacitor having the above, on the dielectric oxide film, a uniform non-porous film made of the conductive organic polymer composition is formed on the entire surface, and the porous non-porous film made of the conductive organic polymer composition is formed thereon. In this case, the material film is laminated.

A second preferred solid electrolytic capacitor according to the present invention comprises a dielectric oxide film formed on a film-forming metal and a conductive organic polymer composition formed as a solid electrolyte on the dielectric oxide film. In a solid electrolytic capacitor having a film, a homogeneous non-porous film composed of a conductive organic polymer composition is formed partially on a dielectric oxide film, and a conductive organic polymer composition A porous film made of a material is laminated.

In the present invention, the conductive organic polymer composition may be any one which can be dissolved in an appropriate solvent such as polyaniline, substituted polyaniline, polythiophene, substituted polythiophene, polypyrrole, substituted polypyrrole, etc.
Although not particularly limited, a conductive polyaniline composition is preferably used. In particular, in the present invention, the conductive polyaniline composition has the general formula (I)

[0013]

Embedded image

(Wherein m and n represent the mole fractions of the quinone diimine structural unit and the phenylenediamine structural unit in the repeating unit, respectively, 0 <m <1, 0 <n <1, m +
n = 1. ), And is composed of N
It is preferable that the composition is obtained by doping an undoped polyaniline having an intrinsic viscosity [η] of not less than 0.4 dL / g in -methyl-2-pyrrolidone with a protonic acid anion.

Further, according to the present invention, there is provided a dielectric oxide film formed on a film-forming metal, and a film of a conductive polyaniline composition formed as a solid electrolyte on the dielectric oxide film, In the method for producing a solid electrolytic capacitor in which at least a part of the film of the conductive polyaniline composition is porous, after contacting a solution obtained by dissolving polyaniline in an organic solvent with the dielectric oxide film, the solvent is removed. After removal, a uniform non-porous film made of polyaniline is formed on the dielectric oxide film, and then the polyaniline solution is brought into contact with the homogeneous non-porous film made of polyaniline, and then the polyaniline is dissolved. However, the organic solvent is extracted and removed by contacting a poor solvent that is miscible with the above solvent to form a polyaniline porous film. At least one of a homogeneous nonporous film and a porous film of the polyaniline is formed on the film, and thereafter, the polyaniline film is brought into contact with a solution of a protonic acid to convert the polyaniline into a protonic acid. There is provided a method for producing a solid electrolytic capacitor, characterized in that a conductive polyaniline composition is obtained by doping with an acid anion.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a film-forming metal foil having a roughened surface or a porous sintered body obtained by sintering a fine powder of a film-forming metal is electrolytically oxidized to oxidize the metal. An object is formed to form a dielectric film, and then a film made of a conductive organic polymer composition is formed thereon so that at least a part thereof is porous, to obtain a capacitor element.

In the present invention, usually, aluminum or tantalum is preferably used as the film-forming metal (anode). Therefore, as the dielectric film, a film of aluminum oxide or tantalum oxide is preferable. It is not limited, and a composite of another metal or alloy can be used.

The polyaniline used in the present invention is composed of a repeating unit represented by the above general formula (I) and is an organic polymer which is dissolved in various organic solvents in an undoped state. Is preferably 0.40 dL / g or more, and particularly preferably 0.50 dL / g or more. Although the upper limit of the intrinsic viscosity “η” is not particularly limited, it is usually 2.5 dL / g or less, preferably 2.0 dL / g or less from the viewpoint of easiness of film formation. Such polyaniline (hereinafter referred to as solvent-soluble polyaniline) is already known as described in detail in JP-A-3-52929.

Such a solvent-soluble polyaniline can be obtained by first preparing a conductive polyaniline composition doped with a protonic acid and then undoping the composition. Therefore, first, the production of the conductive polyaniline composition doped with the above proton acid will be described.

Such a conductive polyaniline composition comprises:
Preferably, the aniline is kept in a suitable solvent in the presence of a protic acid such as hydrochloric acid or sulfuric acid at a temperature of 5 ° C. or less, preferably 0 ° C. or less, and a suitable oxidizing agent such as It can be obtained by oxidatively polymerizing aniline using ammonium disulfate, preferably in an amount of 1 to 1.25 mol part per 1 mol part of aniline.
Next, the solvent-soluble polyaniline can be obtained by undoping the conductive polyaniline composition doped with a protonic acid with a basic substance.

As the above-mentioned solvent, those which dissolve aniline, protonic acid and oxidizing agent and which are not oxidized by the oxidizing agent are used. Water is most preferably used,
However, if necessary, alcohols such as methanol and ethanol, nitriles such as acetonitrile, polar solvents such as N-methyl-2-pyrrolidone and dimethylsulfoxide, ethers such as tetrahydrofuran, and organic acids such as acetic acid may also be used. Can be. Also, a mixed solvent of these organic solvents and water can be used.

In particular, in the above reaction, the reaction temperature is set to 0.
C. It is preferable that the intrinsic viscosity [η] measured at 30 ° C. in N-methyl-2-pyrrolidone after dedoping (hereinafter the same) is 1.0 dL / g.
An organic solvent-soluble polyaniline having the above high molecular weight can be obtained.

In this way, a conductive polyaniline composition doped with a protonic acid can be obtained by oxidative polymerization of aniline. Such a doped polyaniline composition forms a salt with the protonic acid. Therefore, it does not dissolve in an organic solvent as described below. However, by dedoping the solvent-insoluble polyaniline composition, it is possible to obtain a solvent-soluble polyaniline that is soluble in various organic solvents as described below.

Since this undoping is a kind of neutralization reaction, after oxidative polymerization of the aniline, it is directly added to the reaction mixture containing the conductive polyaniline composition, for example, ammonia water or sodium hydroxide. A basic substance may be added, or the conductive polyaniline composition may be once separated and then acted on by a basic substance.

The conductive polyaniline composition in a doped state obtained by the oxidative polymerization of aniline as described above comprises:
Usually, it has a conductivity of 10 ⁻⁶ S / cm or more and exhibits a blackish green color, but after undoping, it is purple or a purple-colored copper. This discoloration is because the amine nitrogen of the salt structure in the polyaniline composition was changed to a free amine. The conductivity is usually on the order of 10 ^-10 S / cm.

The undoped polyaniline thus obtained has a high molecular weight and is soluble in various organic solvents. The polyaniline that can be suitably used in the present invention and is soluble in an organic solvent is N-
Intrinsic viscosity [η] measured at 30 ° C in methylpyrrolidone
Has 0.40 dL / g or more, for example, N-methyl-2.
-Pyrrolidone, N, N-dimethylacetamide, N, N
-Dimethylformamide, dimethylsulfoxide, 1,3
-It is dissolved in an organic solvent such as dimethyl-2-imidazolidinone and sulfolane. The solubility of the polyaniline in the undoped state in such an organic solvent depends on its average molecular weight and the solvent, but usually 0.5 to 100% of the polyaniline is dissolved to obtain a 1 to 30% by weight solution. be able to. In particular, the polyaniline in the undoped state is N-methyl-
It shows high solubility in 2-pyrrolidone, and usually 20 to 100% of polyaniline can be dissolved to obtain a 3 to 30% by weight solution. Therefore, in the present invention, the solvent-soluble polyaniline is usually used as a solution of about 1 to 20% by weight. As the concentration of polyaniline increases, the viscosity of the solution increases. However, the solvent-soluble polyaniline does not dissolve in tetrahydrofuran, 80% aqueous acetic acid, 60% aqueous formic acid, acetonitrile, and the like.

In the solvent-soluble polyaniline represented by the general formula (I), the values of m and n can be adjusted by oxidizing or reducing the polyaniline. That is, by reducing, m can be reduced and n can be increased. Conversely, if oxidized, m can be increased and n can be reduced. When the quinone diimine structural unit in the polyaniline is reduced by the reduction of the polyaniline, the solubility of the polyaniline in the organic solvent is increased. Also, the viscosity of the solution is lower than before the reduction.

The solid electrolytic capacitor according to the present invention comprises a dielectric oxide film formed on a film-forming metal, and a conductive organic polymer composition formed on the dielectric oxide film as a solid electrolyte, preferably a conductive organic polymer composition. A conductive polyaniline composition film, wherein at least a portion of the conductive organic polymer composition film is porous.

More specifically, as a first embodiment, a uniform non-porous film made of conductive polyaniline is formed on the entire surface of the dielectric oxide film, and the conductive polyaniline is preferably formed on the entire surface. A non-porous film made of the composition is laminated. The conductive polyaniline film having such an asymmetric structure first forms a uniform nonporous film made of polyaniline on a dielectric oxide film, and then forms a nonporous film made of polyaniline thereon. Thereafter, these polyaniline films can be obtained by doping with a protonic acid solution.

In a second embodiment, a uniform non-porous film made of a conductive polyaniline composition is partially formed on a dielectric oxide film, and a porous non-porous film made of a conductive polyaniline composition is entirely formed thereon. The membrane is laminated. The conductive polyaniline film having such an asymmetric structure is formed by first forming a homogeneous nonporous film partially composed of polyaniline on a dielectric oxide film, and then forming a nonporous film entirely composed of polyaniline on the dielectric oxide film. And then doping these polyaniline films with a protonic acid solution.

In the present invention, in order to form a uniform non-porous film made of conductive polyaniline on a dielectric oxide film, the above-mentioned polyaniline solution is applied on the dielectric film or the dielectric is converted into a polyaniline solution. After immersion, if necessary, heating is performed to evaporate and remove the solvent from the polyaniline solution, whereby a homogeneous film made of polyaniline can be formed on the dielectric film. Further, in order to form a uniform non-porous film made of conductive polyaniline on the dielectric oxide film, it is necessary to apply the polyaniline solution on the dielectric film, or to immerse the dielectric in the polyaniline solution, The solvent may be removed by evaporating the solvent under reduced pressure as needed, or under heating as needed. In order to partially form a uniform non-porous film made of conductive polyaniline on the dielectric oxide film, for example, after masking a part of the dielectric oxide film with an adhesive film or the like, as described above. After forming the film and forming the film, the film may be peeled off.

As the organic solvent for the polyaniline solution, various ones are used as described above.
Preferably, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethylacetamide and the like are used. Among them, N-methyl-2-pyrrolidone is particularly preferably used.

In this manner, a uniform non-porous film made of conductive polyaniline is formed on the dielectric oxide film, and then a polyaniline solution is applied thereon, and then the polyaniline solution is applied to the polyaniline. Immersion in a solvent, ie, a solvent that does not dissolve polyaniline but is soluble in the solvent of the polyaniline solution (that is, miscible with the solvent of the polyaniline solution), extracts and removes the solvent from the coating film, and coagulates the polyaniline. Thereby, a porous film made of polyaniline can be formed. After being immersed in a poor solvent, heating may be performed, if necessary, to quickly remove the solvent from the coating film.

As the poor solvent, although it depends on the solvent that forms the polyaniline solution, usually, water is preferably used, and lower aliphatic alcohols and lower aliphatic ketones are also used. The lower aliphatic alcohols include, for example, methanol, ethanol, isopropyl alcohol, and the like, and the lower aliphatic ketones include, for example, acetone.

After the polyaniline film, which is at least partially porous, is formed on the dielectric film in this manner,
By doping this with a protonic acid solution, it is possible to impart conductivity to the polyaniline.
The protonic acid used in the doping treatment is preferably an organic acid having an acid dissociation constant pKa value of 4.8 or less.

As the above-mentioned protonic acid, an organic sulfonic acid is preferably used. Specific examples of organic sulfonic acids include, for example, alkylsulfonic acids such as dodecylsulfonic acid, dialkylsulfonic acids such as ethanedisulfonic acid, alkylbenzenesulfonic acids, dialkylbenzenesulfonic acids, alkylnaphthalenesulfonic acids,
Dialkylnaphthalenesulfonic acid, trialkylnaphthalenesulfonic acid, camphorsulfonic acid, acrylamide-t-butylsulfonic acid, p-toluenesulfonic acid,
Phenolsulfonic acid, sulfobenzoic acid, sulfoacetic acid,
Examples thereof include sulfosuccinic acid, carbazole disulfonic acid, terphenyl disulfonic acid, diphenylmethane disulfonic acid, naphthalenesulfonic acid-formalin condensate, polyvinylsulfonic acid, polyvinylsulfuric acid, and polystyrenesulfonic acid.

The concentration of the protonic acid solution depends on the temperature of the doping treatment and the thickness of the formed polyaniline film, but is usually preferably 1 to 70% by weight. Also, the temperature of the doping process is suitably about 15 to 85 ° C. If the treatment is performed at a high temperature, the doping process time can be shortened. However, if the treatment is performed at an excessively high temperature, the mechanical strength of the polyaniline film deteriorates.

To dope the polyaniline film, the polyaniline film is immersed in the above-mentioned protonic acid solution, or the protonic acid solution is brought into contact with the polyaniline film by coating or spraying. I just need.

According to the present invention, as described above, a uniform nonporous film made of polyaniline is formed on a dielectric film, and then a porous film made of polyaniline is formed thereon, and thereafter, It is advantageous to impart conductivity by doping the polyaniline by bringing the asymmetric structure membrane composed of the homogeneous nonporous polyaniline and the porous membrane made of polyaniline into contact with a protonic acid solution. However, if necessary, a uniform non-porous film made of polyaniline is formed on the dielectric film, which is contacted with a protonic acid solution to perform doping treatment, and then a porous polyaniline film is formed thereon. A membrane may be formed and contacted with a protonic acid solution, thus doping a polyaniline asymmetric membrane.

According to the present invention, a homogeneous non-porous film partially composed of polyaniline is formed on a dielectric oxide film,
A non-porous film partially made of polyaniline may be formed thereon. However, at this time, it is necessary that at least one of the above-mentioned homogeneous nonporous film and the porous film of polyaniline is formed on the dielectric oxide film.

[0041]

As described above, the solid electrolytic capacitor according to the present invention has, as a solid electrolyte, a film made of a conductive polyaniline composition that is at least partly porous. , And the occurrence of defects such as cracks can be prevented, and a solid electrolytic capacitor having excellent characteristics can be obtained.

[0042]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

REFERENCE EXAMPLE 1 (Production of quinonediimine / phenylenediamine-type conductive polyaniline composition in a doped state by oxidative polymerization of aniline) 6000 g of distilled water was placed in a 10-L separable flask equipped with a stirrer, a thermometer, and a straight pipe adapter. 360 mL of 36% hydrochloric acid and 400 g (4.295 mol) of aniline were charged in this order to dissolve the aniline. Separately, while cooling with ice water, 434 g (4.295 mol) of 97% concentrated sulfuric acid was added to 1493 g of distilled water in a beaker and mixed to prepare an aqueous sulfuric acid solution. This aqueous sulfuric acid solution was added to the separable flask, and the entire flask was cooled to −4 ° C. in a low-temperature constant temperature bath. Next, distilled water 2 was placed in a beaker.
To 293 g, 980 g of ammonium peroxodisulfate (4.
295 mol) was added and dissolved to prepare an oxidizing agent aqueous solution.

The entire flask was cooled in a low-temperature constant-temperature bath, and while maintaining the temperature of the reaction mixture at -3 ° C. or lower, the peroxo acid solution of the aniline salt was added to the acidic aqueous solution of the aniline salt with stirring using a tubing pump. An aqueous solution of ammonium disulfate was gradually added dropwise at a rate of 1 mL / min or less. Initially, the colorless and transparent solution turned from green-blue to black-green as the polymerization proceeded, and then a black-green powder was deposited.

Although the temperature of the reaction mixture rises during the deposition of the powder, it is necessary to obtain a high molecular weight polymer.
It is important to keep the temperature in the reaction system at 0 ° C. or lower, preferably at -3 ° C. or lower. After the powder deposition, the dropping rate of the aqueous solution of ammonium peroxodisulfate may be slightly increased, for example, to about 8 mL / min. However, also in this case, it is necessary to adjust the dropping speed so as to keep the temperature at −3 ° C. or lower while monitoring the temperature of the reaction mixture.
After completion of the dropwise addition of the aqueous solution of ammonium peroxodisulfate in 7 hours, the mixture was further cooled to -3 ° C for 1 hour.
Stirring was continued at the following temperatures.

The powder thus obtained was separated by filtration, washed with water, washed with acetone, and vacuum dried at room temperature to obtain 430 g of a blackish green quinonediimine / phenylenediamine type conductive polyaniline composition powder.

This was pressed into a disk having a diameter of 13 mm and a thickness of 700 μm, and was subjected to the van der Pauw method by the following method.
The measured conductivity was 14 S / cm.
(Production of quinone diimine / phenylenediamine type solvent-soluble polyaniline by dedoping of conductive organic polymer composition)

350 g of the doped conductive boraniline composition powder was added to 4 L of 2N aqueous ammonia,
The mixture was stirred for 5 hours at a rotation speed of 5000 rpm with an auto homomixer. The mixture turned from black green to bluish purple.

The powder was filtered off with a Buchner funnel and washed repeatedly with distilled water while stirring in a beaker until the filtrate became neutral, and then washed with acetone until the filtrate became colorless. did. Thereafter, the powder was vacuum-dried at room temperature for 10 hours to obtain 280 g of a black-brown undoped organic solvent-soluble quinonediimine / phenylenediamine type polyaniline powder.

This polyaniline was soluble in N-methyl-2-pyrrolidone, and the solubility was 8 g (7.4%) per 100 g of the same solvent. The intrinsic viscosity [η] measured at 30 ° C. using this as a solvent was 1.23 dl / g.

Comparative Example 1 As a film-forming metal, a porous sintered body (volume: 20.8 mm ³ ) obtained by sintering fine powder of tantalum was used.
A DC voltage of 100 V was applied in an aqueous solution of phosphoric acid by weight to form a tantalum oxide film on the surface of the porous sintered body.

In 47.5 g of N-methyl-2-pyrrolidone, 2.5 g of the organic solvent-soluble quinone diimine / phenylenediamine type polyaniline obtained in Reference Example 1 was dissolved.
A polyaniline solution was prepared.

After the above-mentioned tantalum oxide film was immersed in the above-mentioned polyaniline solution, it was placed in a hot air circulation dryer (80 ° C.) for 10 minutes.
After heating and drying for a minute, a uniform nonporous film made of polyaniline was formed on the tantalum oxide film. This operation was repeated six times to cover the entire surface of the tantalum oxide film with a uniform nonporous film made of polyaniline.

In this way, after forming a uniform nonporous film made of polyaniline on the surface of the tantalum oxide film, it is immersed in a 10% by weight aqueous solution of polyvinyl sulfonic acid at 70 ° C. for 2 hours to dope polyaniline. ,
Washed with ethanol and dried at 60 ° C. for 20 minutes. Thereafter, a conductive paste was applied, and a cathode lead was attached. Table 1 shows the capacitor characteristics of the capacitor element thus obtained. Further, this element was molded with an epoxy resin for molding to complete a tantalum capacitor. Table 2 shows the characteristics of the obtained capacitors.

Example 1 In the same manner as in Comparative Example 1, a tantalum oxide film was formed on the surface of a porous sintered body of tantalum. This tantalum oxide film was immersed in the same polyaniline solution as in Comparative Example 1, and then dried by heating in a circulating hot air dryer (80 ° C.) for 10 minutes to form a uniform nonporous film made of polyaniline on the tantalum oxide film. did. This operation was repeated six times to cover the entire surface of the tantalum oxide film with a uniform nonporous film made of polyaniline.

Next, the tantalum oxide film covered with the homogeneous nonporous film made of polyaniline was immersed in the same polyaniline solution as described above, and then immersed in distilled water at room temperature to obtain a solvent, N-methyl. -2-Pyrrolidone is extracted and removed, and polyaniline is coagulated to form a porous film made of polyaniline on the homogeneous nonporous film made of polyaniline.
Dry for minutes and allow the water to evaporate. This operation was repeated twice to cover the surface of the homogeneous nonporous film made of polyaniline with a porous film made of polyaniline.

Thereafter, in the same manner as in Comparative Example 1, a polyaniline doping treatment was performed, a conductive paste was applied, and a cathode lead was attached. Table 1 shows the capacitor characteristics of the element thus obtained. Further, this element was molded with an epoxy resin for molding to complete a tantalum capacitor. Table 2 shows the obtained capacitor characteristics.
Shown in

Example 2 In the same manner as in Comparative Example 1, a tantalum oxide film was formed on the surface of a porous sintered body of tantalum. This tantalum oxide film was immersed in the same polyaniline solution as in Comparative Example 1, and then dried by heating in a hot air circulating drier (80 ° C.) for 10 minutes to form a uniform nonporous film made of polyaniline on the tantalum oxide film. did. This operation was repeated four times to partially cover the surface of the tantalum oxide film with a homogeneous nonporous film made of polyaniline.

Next, the tantalum oxide film partially covered with the homogeneous nonporous film made of polyaniline is immersed in the same polyaniline solution as described above, and then immersed in distilled water at room temperature to obtain a solvent. N-methyl-2-pyrrolidone is extracted and removed, and polyaniline is coagulated to form a porous film on a homogeneous nonporous film made of polyaniline. Then, the film is dried at 80 ° C. for 10 minutes to remove water. Was evaporated. This operation was repeated twice to completely cover the homogeneous nonporous film made of polyaniline with the porous film made of polyaniline.

Thereafter, in the same manner as in Comparative Example 1, polyaniline doping treatment was performed, a conductive paste was applied, and a cathode lead was attached. Table 1 shows the capacitor characteristics of the element thus obtained. Further, this element was molded with an epoxy resin for molding to complete a tantalum capacitor. Table 2 shows the capacitor characteristics of the obtained device.

Example 3 In the same manner as in Comparative Example 1, a tantalum oxide film was formed on the surface of a porous tantalum sintered body. This tantalum oxide film was immersed in the same polyaniline solution as in Comparative Example 1, and then dried by heating in a hot air circulating drier (80 ° C.) for 10 minutes to form a uniform nonporous film made of polyaniline on the tantalum oxide film. did. This operation was repeated four times to partially cover the surface of the tantalum oxide film with a homogeneous nonporous film made of polyaniline.

Next, the tantalum oxide film partially covered with the homogeneous nonporous film made of polyaniline is immersed in the same polyaniline solution as described above, and then immersed in isopropyl alcohol at room temperature to obtain a solvent. N-methyl-2-pyrrolidone was extracted and removed, and polyaniline was coagulated to form a porous film made of polyaniline. Thereafter, the film was dried at 60 ° C. for 10 minutes to evaporate isopropyl alcohol. This operation was repeated three times to cover the homogeneous nonporous film made of polyaniline with the porous film made of polyaniline.

Thereafter, in the same manner as in Comparative Example 1, polyaniline doping treatment was performed, a conductive paste was applied, and the capacitor characteristics of the element obtained in this manner, to which a cathode lead was attached, are shown in Table 1. Further, this element was molded with an epoxy resin for molding to complete a tantalum capacitor. Table 2 shows the obtained capacitor characteristics.

[0064]

[Table 1]

[0065]

[Table 2]

According to Examples 1 to 3, the characteristics of the capacitor element and the characteristics of a capacitor obtained by molding the element with an epoxy resin are almost the same, but Comparative Example 1
According to the above, when the device is molded with an epoxy resin, defects such as cracks occur in the conductive polyaniline film, and the electric resistance increases. As a result, the obtained capacitor has a higher characteristic than the device. It is understood that is significantly deteriorated.

Claims (7)

[Claims] 1. A solid electrolytic capacitor comprising: a dielectric oxide film formed on a film-forming metal; and a film of a conductive organic polymer composition formed as a solid electrolyte on the dielectric oxide film. A solid electrolytic capacitor, wherein at least a part of a film of the conductive organic polymer composition is porous. 2. A solid electrolytic capacitor comprising: a dielectric oxide film formed on a film-forming metal; and a film of a conductive organic polymer composition formed as a solid electrolyte on the dielectric oxide film. A homogeneous non-porous film made of a conductive organic polymer composition is formed on the entire surface of the body oxide film, and a porous film made of the conductive organic polymer composition is laminated thereon. 2. The solid electrolytic capacitor according to 1. 3. A solid electrolytic capacitor comprising: a dielectric oxide film formed on a film-forming metal; and a film of a conductive organic polymer composition formed on the dielectric oxide film as a solid electrolyte. On the body oxide film, a uniform non-porous film composed of a conductive organic polymer composition is partially formed, and a non-porous film composed of a conductive organic polymer composition is laminated on the entire surface. The solid electrolytic capacitor according to claim 1, wherein 4. The solid electrolytic capacitor according to claim 1, wherein the conductive organic polymer composition is a conductive polyaniline composition. 5. The conductive polyaniline composition has a general formula (I): (In the formula, m and n each represent a mole fraction of the quinone diimine structural unit and the phenylenediamine structural unit in the repeating unit, and are represented by 0 <m <1, 0 <n <1, and m + n = 1.) Consisting of repeating units, N-methyl-
The intrinsic viscosity [η] measured at 30 ° C. in 2-pyrrolidone is
The solid electrolytic capacitor according to any one of claims 1 to 4, wherein the composition is a composition obtained by doping a polyaniline in an undoped state of 0.4 dL / g or more with a protonic acid anion. 6. A conductive polyaniline composition comprising: a dielectric oxide film formed on a film-forming metal; and a film of a conductive polyaniline composition formed as a solid electrolyte on the dielectric oxide film. In the method for producing a solid electrolytic capacitor in which at least a part of the film is porous, after contacting the dielectric oxide film with a solution obtained by dissolving polyaniline in an organic solvent, the solvent is removed by evaporation. Forming a homogeneous non-porous film made of polyaniline on the dielectric oxide film, and then contacting the polyaniline solution with the homogeneous non-porous film made of polyaniline,
The polyaniline does not dissolve, but is brought into contact with a poor solvent that is miscible with the solvent, and the organic solvent is extracted and removed to form a polyaniline porous film. At least one of a homogeneous nonporous film and a porous film of the polyaniline is formed, and thereafter, the polyaniline films are brought into contact with a solution of a protonic acid, and the polyaniline is treated with a protonate anion. A method for producing a solid electrolytic capacitor, comprising doping a conductive polyaniline composition. 7. The conductive polyaniline composition according to the general formula (I) (In the formula, m and n each represent a mole fraction of the quinone diimine structural unit and the phenylenediamine structural unit in the repeating unit, and are represented by 0 <m <1, 0 <n <1, and m + n = 1.) Consisting of repeating units, N-methyl-
The intrinsic viscosity [η] measured at 30 ° C. in 2-pyrrolidone is
7. The method for producing a solid electrolytic capacitor according to claim 6, wherein the composition is obtained by doping a polyaniline in an undoped state of 0.4 dL / g or more with a protonic acid anion.