JPH11307396A - Method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

[PROBLEMS] To provide a method for manufacturing a solid electrolytic capacitor capable of efficiently forming a low-resistance conductive polymer solid electrolyte by chemical oxidation polymerization with respect to a solid electrolytic capacitor having a low impedance in a high frequency region. And SOLUTION: An anode body 12a, 1 made of a porous valve metal.
After impregnating the dielectric oxide film 13 formed in 2b with an oxidizing agent solution having an electrode potential higher than the oxidation potential of the heterocyclic compound and / or its derivative and drying, the anode bodies 12a and 12b are at least The heterocyclic compound and / or a derivative thereof is immersed in a dilute solution containing 1 part by weight or less with respect to 100 parts by weight of water and chemically oxidized and polymerized to form a conductive polymer solid electrolyte 14, and then colloidal graphite 15, a conductive polymer solid electrolyte 14 can be efficiently formed by a method of applying a silver paint 16 to produce a solid electrolytic capacitor element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a solid electrolytic capacitor using a conductive polymer formed by chemical oxidative polymerization of a heterocyclic compound and / or a derivative thereof as a solid electrolyte.

[0002]

2. Description of the Related Art In recent years, with the increase in the frequency of power supply circuits for electronic devices, all electronic components have been required to have excellent high-frequency characteristics. The solid electrolytic capacitor is no exception, and to achieve this, the surface condition of the anode body, the method of forming the oxide film, the improvement of the solid electrolyte, the surface condition of the cathode layer,
Investigations and improvements have been made from various angles, such as the structure of capacitor elements. Among them, improvement of solid electrolytes is one of the technologies that has recently attracted much attention in the development of new materials.

FIGS. 5 (a) and 5 (b) are partially cutaway perspective views showing the structure of a solid electrolytic capacitor element constituting this type of solid electrolytic capacitor. The material used for the anode body is aluminum or tantalum. An anode foil using an inorganic solid electrolyte such as manganese dioxide or lead dioxide as an electrolyte, having internal terminals 51a and 51b as shown in FIG. Anode plate or anode body 52 obtained by sintering fine powder
a, 52b on the surface of the dielectric oxide film 53 by anodic oxidation
Is formed, impregnated with an aqueous solution of manganese nitrate or the like, baked the solid electrolyte 54 using a thermal decomposition reaction, and then coated with colloidal graphite 55 and silver paint 56 to form a cathode layer. I have.

FIG. 6 is a sectional view schematically showing the structure of such a solid electrolytic capacitor element. The solid electrolytic capacitor using the solid electrolytic capacitor element configured as described above has an advantage that the temperature dependency is small and the resistance in a high frequency region is low compared to an aluminum electrolytic capacitor using an electrolytic solution due to the characteristics of the electrolyte. But,
On the other hand, it has a disadvantage that the withstand voltage is low and the productivity is slightly disadvantageous due to the restriction of the production method.

In order to further reduce the resistance of the solid electrolyte 54, a charge transfer complex such as TC
Commonly known as NQ salts, organic semiconductor capacitors, and conductive polymers made by polymerizing and conducting heterocyclic compounds such as pyrrole, thiophene, and furan, have been put into practical use. I have.

[0006] Among them, the conductive polymer has a characteristic that its specific resistance is remarkably low. Although it is a solid electrolyte which is effective in reducing the resistance of a solid electrolytic capacitor, the dielectric inside the anode body made of a porous valve metal is used. The formation of a coating film that is uniform, dense, and excellent in adhesion to an oxide film is extremely restricted. For this point, for example, Japanese Patent Publication No. 4-74853 discloses an electrolytic solution. The conductive polymer film formed by oxidative polymerization gives extremely dense and excellent conductivity under the selected conditions, but it is extremely difficult to form the film even inside the pores. For this reason, a method has been disclosed in which a conductive polymer film is formed inside pores by chemical oxidation polymerization, and then electrolytic oxidation polymerization is performed using the film as an anode.

[0007]

However, since it is advantageous to form a conductive polymer film even inside a porous body as in the above-mentioned conventional manufacturing method, it is difficult to perform chemical oxidation polymerization. Although it is a manufacturing method that compensates for one major disadvantage, the surface of the dielectric oxide film in the pores of the anode body is greatly affected by the surface tension of the liquid to be immersed and the wettability of the surface of the dielectric oxide film, It is extremely difficult to form a uniform, dense, and highly adherent conductive polymer film inside the pores.

In addition, chemical oxidative polymerization essentially forms an electroconductive polymer film by causing an oxidative polymerization reaction to polymerize when an oxidizing agent and a heterocyclic compound and / or a derivative thereof are associated with each other. Therefore, the formation location, conductivity, adhesion, film density, and the like greatly depend on the formation conditions and method. Contrary to the low specific resistance of the electrolyte itself, this has a problem that it contributes to lot variations in the electrical characteristics of the solid electrolytic capacitor actually obtained.

Therefore, in forming the conductive polymer on the surface of the dielectric oxide film, the solution of the oxidizing agent and the heterocyclic compound and / or a derivative thereof is sequentially supplied from the pores of the anode body to the outer layer of the anode body. It is desirable that the conductive polymer is formed from the outer layer portion of the anode body in a general method, so that it is necessary to secure preferable electric characteristics of the solid electrolytic capacitor. For that reason, the reality was that it had great restrictions.

[0010] The present invention solves the problem of forming a coating film of a conductive polymer which is a conventional solid electrolyte which is effective in lowering the resistance, and uniformly deposits the conductive polymer on the surface of the dielectric oxide film. It is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor that can be applied to a product requiring low impedance in a high frequency region by forming a coating on a solid electrolytic capacitor.

[0011]

In order to solve the above-mentioned problems, a method for manufacturing a solid electrolytic capacitor according to the present invention comprises providing a heterocyclic compound and a heterocyclic compound on a dielectric oxide film formed on an anode body made of a porous valve metal. And / or impregnated with an oxidizing agent solution having an electrode potential higher than the oxidation potential of the derivative thereof and drying the same. Then, the dried anode body is replaced with at least the above-mentioned heterocyclic compound and / or derivative thereof in 100 parts by weight of water. A solid electrolyte composed of a conductive polymer is formed by immersion in a dilute solution containing not more than 1 part by weight of the polymer and chemical oxidation polymerization is performed, and a cathode layer is formed on the solid electrolyte. . According to this manufacturing method, the solution of the oxidizing agent and the heterocyclic compound and / or the derivative thereof can be sequentially and easily associated with each other in the outer layer portion from the pore portion of the anode body. A uniform coating can be formed on the surface of the body oxide film.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention provides a method for measuring the oxidation potential of a heterocyclic compound and / or a derivative thereof on a dielectric oxide film formed on an anode body made of a porous valve metal. After impregnating with an oxidizing agent solution having a high electrode potential and drying it, the dried anode body contains at least 1 part by weight of the heterocyclic compound and / or derivative thereof with respect to 100 parts by weight of water. A solid electrolyte made of a conductive polymer is formed by immersing in a dilute solution and performing chemical oxidation polymerization, and a cathode layer is formed on the solid electrolyte.According to this manufacturing method,
By drying, the oxidizing agent can be uniformly coated from the surface of the dielectric oxide film in the pores of the anode body to the surface of the dielectric oxide film in the outer layer of the anode body, and when immersed in a dilute solution, The dilute solution quickly reaches the surface of the dielectric oxide film in the pores of the anode body to form a solid electrolyte made of a conductive polymer, and the heterocyclic compound and its derivative are dissolved in 100 parts by weight of water. On the other hand, a dilute solution containing less than 1 part by weight causes a mild chemical oxidative polymerization reaction due to its low concentration, so that a solid electrolyte is gradually formed without plugging the pores of the pores of the anode body. Therefore, it has the effect that a solid electrolytic capacitor having excellent electrical performance can be efficiently obtained up to the surface of the dielectric oxide film in the pores of the anode body.

According to a second aspect of the present invention, there is provided an oxidizing agent having an electrode potential higher than that of a heterocyclic compound and / or a derivative thereof on a dielectric oxide film formed on an anode body made of a porous valve metal. After the solution is impregnated and dried, the dried anode body is immersed in a dilute solution containing at least 1 part by weight of the above heterocyclic compound and / or derivative thereof in 100 parts by weight of water. By repeating the step of oxidative polymerization at least twice or more, a solid electrolyte made of a conductive polymer is formed, and a cathode layer is formed on the solid electrolyte. A solid electrolyte made of conductive polymer can be formed uniformly from the surface of the dielectric oxide film in the pores of the anode body to the surface of the dielectric oxide film in the outer layer of the anode body. An effect that it is possible to obtain an excellent solid electrolytic capacitor more readily electrical performance.

According to a third aspect of the present invention, there is provided an oxidizing agent having an electrode potential higher than that of a heterocyclic compound and / or a derivative thereof on a dielectric oxide film formed on an anode body made of a porous valve metal. After repeating the step of impregnating the solution and drying it a plurality of times, the diluted anode body is a dilute solution containing at least a heterocyclic compound and / or a derivative thereof within 1 part by weight with respect to 100 parts by weight of water. To form a solid electrolyte made of a conductive polymer by performing chemical oxidative polymerization on the solid electrolyte, and to form a cathode layer on the solid electrolyte. By oxidative polymerization, a solid electrolyte consisting of a large amount of conductive polymer can be formed uniformly from the surface of the dielectric oxide film in the pores of the anode body to the surface of the dielectric oxide film in the outer layer of the anode body. Because, such an action can be obtained solid electrolytic capacitor excellent in more efficient electrical performance.

According to a fourth aspect of the present invention, in the method of any one of the first to third aspects, when the anode body having been dried is immersed in a dilute solution and subjected to chemical oxidative polymerization, the anodic body is diluted. The solution temperature is set to 10 ° C. or lower. According to this manufacturing method, the chemical oxidation polymerization reaction is further suppressed because of the low concentration and the low temperature. Since the solid electrolyte is gradually formed without plugging the pores, a solid electrolytic capacitor having excellent electric performance can be obtained more efficiently up to the surface of the dielectric oxide film in the pores of the anode body. It has the action of:

According to a fifth aspect of the present invention, in the method of any one of the first to fourth aspects, when the dried anode body is immersed in a dilute solution and subjected to chemical oxidation polymerization, the diluted anodic body is treated with the diluted anodic body. By adjusting the pH of the solution to an acidity of at least pH 4 or less, according to this production method, the dopant is easily incorporated at the same time as the chemical oxidative polymerization reaction, and a solid electrolyte having high electric conductivity is obtained. Since the solid electrolytic capacitor is formed by deposition, it has an effect that a solid electrolytic capacitor having more excellent electric performance can be obtained.

According to a sixth aspect of the present invention, in the invention of the fifth aspect, the dilute solution contains naphthalenesulfonic acid and / or a derivative thereof, and the pH thereof is adjusted with sulfuric acid. According to this manufacturing method, the desired dopant is selectively and efficiently taken in at the same time as the chemical oxidation polymerization reaction, and a solid electrolyte having high electric conductivity and excellent heat resistance is deposited and formed. Has the effect that a solid electrolytic capacitor having excellent stability can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described.

First, as shown in FIGS. 1A and 1B,
A 1.4 m thick anode having internal terminals 11a and 11b, obtained by pressing, molding and vacuum sintering tantalum powder.
m, 3.0 mm wide and 3.8 mm long anode bodies 12a, 12b
Was subjected to anodic oxidation at 20 V in a 5% aqueous phosphoric acid solution to form a dielectric oxide film 13. Next, this was impregnated with an oxidizing agent aqueous solution mainly containing 32% by weight of ferric sulfate, 0.7% by weight of sodium naphthalenesulfonate, and 10.5% by weight of ethyl alcohol for 10 minutes. 1
After drying for 0 minute, the dried anode body was adjusted to pH 2 with sulfuric acid.
Then, it was immersed in a dilute 5 ° C. monomer aqueous solution mainly containing 0.5% by weight of a pyrrole monomer, 2% by weight of naphthalenesulfonic acid, and 15% by weight of ethyl alcohol, to perform chemical oxidation polymerization. Such chemical oxidative polymerization is carried out in 5
This operation was repeatedly performed to form the conductive polymer solid electrolyte 14.

Thereafter, in the same manner as in the conventional method of manufacturing a solid electrolytic capacitor, colloidal graphite 15 and silver paint 16 were applied to manufacture a solid electrolytic capacitor element.
The conductive polymer solid electrolyte is obtained by repeating chemical oxidative polymerization five times using a monomer aqueous solution containing 1% by weight and 1.5% by weight of a pyrrole monomer, which is one of the main components constituting the aqueous monomer solution. The solid electrolytic capacitor element formed with No. 14 was also manufactured.

FIG. 2 shows a manufacturing process according to the present embodiment. (Embodiment 2) Hereinafter, a second embodiment of the present invention will be described.

In the present embodiment, the conductive polymer solid electrolyte 14 formed on the outer surfaces of the anode bodies 12a and 12b is obtained by performing the chemical oxidative polymerization once in the first embodiment and three times. Since it is formed by repeating the process and is the same as the first embodiment except for the above, the detailed description is omitted.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described.

In the present embodiment, the conductive polymer solid electrolyte 14 formed on the outer surfaces of the anode bodies 12a and 12b is obtained by repeating the impregnation and drying of the oxidizing agent aqueous solution in the first embodiment three times. And 5 times were formed by repeating chemical oxidative polymerization of dipping each in an aqueous monomer solution 5 times. Since other than this is the same as the first embodiment, Description is omitted.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described.

In the present embodiment, the conductive polymer solid electrolyte 14 formed on the outer surfaces of the anode bodies 12a and 12b is adjusted to the temperature of the aqueous monomer solution of the first embodiment of 10%.
C., 15 ° C., and 25 ° C., each of which was formed by repeating chemical oxidative polymerization five times.
Since the third embodiment is the same as the first embodiment, a detailed description thereof will be omitted.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described.

In the present embodiment, the conductive polymer solid electrolyte 14 formed on the outer surfaces of the anode bodies 12a and 12b is adjusted to have a pH of the aqueous monomer solution of 1 in the first embodiment.
Chemical oxidation polymerization was repeated 5 times each in place of 3, 4 and 5, and each was formed.
Since the third embodiment is the same as the first embodiment, a detailed description thereof will be omitted.

(Comparative Example) As shown in FIGS. 3A and 3B, the thickness of an anode provided with internal terminals 31a and 31b obtained by pressing, molding, and vacuum sintering tantalum powder. Anode body 32a having a size of 1.4 mm, a width of 3.0 mm, and a length of 3.8 mm,
32b was anodized at 20 V in a 5% phosphoric acid aqueous solution to form a dielectric oxide film 33. Next, this was prepared by using 5% by weight of a pyrrole monomer, 2.5% by weight of naphthalenesulfonic acid, and 15% by weight of ethyl alcohol as main components.
C. for 10 minutes, and then immersed for 10 minutes in an oxidizing agent aqueous solution mainly containing 3% by weight of ferric sulfate, 1.5% by weight of sodium naphthalenesulfonate and 15% by weight of ethyl alcohol. Chemical oxidative polymerization was performed. The conductive polymer solid electrolyte 34 was formed by repeating the chemical oxidation polymerization 5 times and repeating the chemical oxidation polymerization 10 times. Thereafter, colloidal graphite 35 and silver paint 36 were applied in the same manner as in the conventional method for manufacturing a solid electrolytic capacitor, to produce a solid electrolytic capacitor element.

FIG. 4 shows a manufacturing process of a comparative example. The basic electrical performance (capacitance, loss tangent, tangent of leakage angle, leakage current, and the like) measured for each of the tantalum solid electrolytic capacitor elements obtained according to Embodiments 1 to 5 of the present invention and the comparative example manufactured as described above. Frequency 10
(0 kHz impedance) is shown in (Table 1).

[0031]

[Table 1]

As is clear from the first embodiment of the present invention (Table 1), when the monomer concentration is too high, the anode body 12a,
The pores of the pores 12b are plugged, and the capacitance is reduced and the variation appears. Thus, the heterocyclic compound and / or derivative thereof in the aqueous monomer solution should have at least 100
It can be said that it must be diluted within 1.5 parts by weight, preferably within 1.0 part by weight based on parts by weight.

Further, the first embodiment of the present invention shown in (Table 1)
As is clear from the second embodiment (monomer 0.5) and the second embodiment, the chemical oxidation polymerization is repeated so that the surface of the dielectric oxide film 13 in the pores of the anode bodies 12a and 12b is gradually removed from the surface of the anode bodies 12a and 12a. Dielectric oxide film 1 on outer layer of 12b
Conductive polymer solid electrolyte 1 even down to the surface of 3
4 can be formed. Under the conditions of the first embodiment and the second embodiment, almost preferable electric performance was obtained when the number of repetitions was about five. Further, as is clear from comparison with the comparative example, it can be said that in the present invention, the conductive polymer solid electrolyte 14 is formed approximately twice as efficiently as the comparative example.

Further, the first embodiment of the present invention shown in (Table 1)
(Monomer 0.5), Embodiment 2 and Embodiment 3
As is clear, the oxidizing agent is repeatedly impregnated in the chemical oxidative polymerization, so that the anode body 12 is formed in one chemical oxidative polymerization.
a, a large amount of the conductive polymer solid electrolyte 1 uniformly from the surface of the dielectric oxide film 13 in the pores of the anode bodies 12a and 12b to the surface of the dielectric oxide film 13 in the outer layers of the anode bodies 12a and 12b.
Since No. 4 is formed, it can be said that preferable electric performance can be efficiently obtained even with a smaller number of times of chemical oxidation polymerization.

Further, the first embodiment of the present invention shown in (Table 1)
As is clear from the value of the impedance of (monomer 0.5) and the fourth embodiment, as the temperature of chemical oxidative polymerization increases, the electric conductivity of the conductive polymer solid electrolyte 14 gradually decreases. In addition, since a milder chemical oxidative polymerization reaction occurs at a lower temperature, a solid electrolyte is gradually deposited and formed without plugging the pores of the pores of the anode bodies 12a and 12b. Stable electrical performance is obtained. In addition, setting the temperature to a low temperature also suppresses the volatilization of the heterocyclic compound and / or its derivative from the aqueous monomer solution, which is preferable from the viewpoint of effective utilization of members and safety and health. Therefore, it can be said that the chemical oxidation polymerization temperature should be controlled at least within 15 ° C, preferably within 10 ° C.

Further, the first embodiment of the present invention shown in (Table 1)
As is clear from the (monomer 0.5) and the impedance value of the fifth embodiment, in an acidic environment where the pH of the chemical oxidative polymerization is 4 or less, the desired dopant is easily and selectively efficiently efficiently simultaneously with the chemical oxidative polymerization reaction. Is taken in, and a solid electrolyte having a high electric conductivity is deposited and formed. However, on the alkali side, only a solid electrolyte having a low electric conductivity is rapidly obtained. Therefore, it can be said that the pH of the chemical oxidative polymerization needs to be maintained in an acidic environment of 4 or less.

In the first to fifth embodiments of the present invention, the anode bodies 12a and 12b are made of a tantalum sintered body. However, the present invention is not limited to this. The same applies to all metals. In addition, an aqueous solution was generally used for the preparation of the solution. Similarly, a single solvent or a solvent for enhancing the dissolution of the heterocyclic compound and its derivative, benzene, naphthalene and its derivative, etc. was used. It goes without saying that the same effect can be expected even when used in combination.

[0038]

As described above, according to the method for manufacturing a solid electrolytic capacitor of the present invention, an oxidizing agent and a heterocyclic compound are used to form a conductive polymer as a solid electrolyte on the surface of a dielectric oxide film. And / or an oxidizing agent solution having an electrode potential higher than the oxidation potential of the heterocyclic compound and / or derivative thereof so that the solution of the derivative can be sequentially and easily associated with the outer layer portion from the pore portion of the anode body. After drying, the dried anode body is immersed in a dilute solution containing at least 1 part by weight of a heterocyclic compound and / or a derivative thereof with respect to 100 parts by weight of water to perform chemical oxidation. Since the conductive polymer solid electrolyte is formed by performing polymerization, the dielectric oxide film on the outer layer of the anode body is dried from the surface of the dielectric oxide film on the pores of the anode body by drying. Can be coated uniformly oxidant up to the surface, and when it is dipped in a dilute solution,
The diluted solution quickly reaches the surface of the dielectric oxide film in the pores of the anode body to form a conductive polymer solid electrolyte.

A dilute solution containing less than 1 part by weight of a heterocyclic compound or a derivative thereof per 100 parts by weight of water causes a mild chemical oxidative polymerization reaction due to its low concentration. It is gradually formed without clogging the hole of the part.

Furthermore, the application of a high-concentration oxidizing agent solution makes it possible to form a conductive polymer solid electrolyte that is approximately twice as efficient as conventional general chemical oxidative polymerization.
Furthermore, in the method of performing chemical oxidative polymerization after repeatedly impregnating with an oxidizing agent, the formation efficiency can be doubled without changing the performance such as the electric conductivity of the conductive polymer solid electrolyte. Is extremely stable and has excellent electrical characteristics and reliability, and at the same time, can significantly improve productivity as compared with the conventional manufacturing method.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a solid electrolytic capacitor element obtained by a method for manufacturing a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram showing a manufacturing process of a solid electrolytic capacitor element.

FIG. 3 is a partially cutaway perspective view showing a solid electrolytic capacitor element obtained according to a comparative example.

FIG. 4 is a manufacturing process diagram showing a manufacturing process of a solid electrolytic capacitor element of a comparative example.

FIG. 5 is a partially cutaway perspective view showing a solid electrolytic capacitor element obtained by a conventional solid electrolytic capacitor manufacturing method.

FIG. 6 is a cross-sectional view schematically showing a configuration of a conventional solid electrolytic capacitor.

[Explanation of symbols]

 11a, 11b Internal terminal 12a, 12b Anode body 13 Dielectric oxide film 14 Conductive polymer solid electrolyte 15 Colloidal graphite 16 Silver paint 31a, 31b Internal terminal 32a, 32b Anode body 33 Dielectric oxide film 34 Conductive polymer solid electrolyte 35 Colloidal graphite 36 Silver paint

Claims (6)

[Claims] An oxidizing agent solution having an electrode potential higher than the oxidation potential of a heterocyclic compound and / or a derivative thereof is impregnated on a dielectric oxide film formed on an anode body made of a porous valve metal. After drying, the dried anode body is immersed in a dilute solution containing at least 1 part by weight of the above-mentioned heterocyclic compound and / or derivative thereof in 100 parts by weight of water to carry out chemical oxidation polymerization. A method for manufacturing a solid electrolytic capacitor in which a solid electrolyte made of a conductive polymer is formed, and a cathode layer is formed on the solid electrolyte. 2. An oxidizing agent solution having an electrode potential higher than the oxidation potential of a heterocyclic compound and / or a derivative thereof is impregnated on a dielectric oxide film formed on an anode body made of a porous valve metal. After drying, at least two steps of immersing the dried anode body in a dilute solution containing at least 1 part by weight of the above heterocyclic compound and / or derivative thereof with respect to 100 parts by weight of water to chemically oxidize and polymerize the anode body are included. A method for producing a solid electrolytic capacitor in which a solid electrolyte made of a conductive polymer is formed by repeating the above process at least twice, and a cathode layer is formed on the solid electrolyte. 3. An oxidizing agent solution having an electrode potential higher than that of a heterocyclic compound and / or a derivative thereof is impregnated on a dielectric oxide film formed on an anode body made of a porous valve metal, and After the drying step is repeated a plurality of times, the dried anode body is immersed in a dilute solution containing at least 1 part by weight of the heterocyclic compound and / or its derivative with respect to 100 parts by weight of water to perform chemical oxidation. A method for producing a solid electrolytic capacitor in which a solid electrolyte made of a conductive polymer is formed by performing polymerization, and a cathode layer is formed on the solid electrolyte. 4. When the dried anode body is immersed in a dilute solution for chemical oxidation polymerization, the temperature of the dilute solution is set to 10 ° C.
The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the method is performed as follows. 5. The method according to claim 1, wherein when the anode body after drying is immersed in a dilute solution and subjected to chemical oxidative polymerization, the pH of the dilute solution is adjusted to an acidity of at least pH 4 or less. The method for producing a solid electrolytic capacitor according to any one of the above. 6. The method for producing a solid electrolytic capacitor according to claim 5, wherein the dilute solution contains naphthalenesulfonic acid and / or a derivative thereof, and the pH thereof is adjusted using sulfuric acid.