JPH11274008A - Electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor of high capacity achievement percentage by forming conductive polymer, which is a cathode electrolyte of an electrolytic capacitor, to be homogeneous as far as the inside of a hole at a minute part of a capacitor porous body. SOLUTION: A depression process is performed, when the inside of porous body is impregnated with polymerization solution which is used for forming a conductive high polymer layer at a capacitor porous body, so that the coverage percentage of a dielectric oxide film with the conductive high polymer is improved to provide a superior capacitor of high capacity generation percentage. Also before the solution impregnation, the surface of hole of the porous body is made wet with the solvent vapor of the solution or the solvent vapor of affinity with the solution, so that the coverage percentage of the dielectric oxide film with the conductive high polymer is improved to provide a superior electrolytic capacitor of high capacity generation percentage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor using a valve metal such as aluminum or tantalum and a method for manufacturing the same, and more particularly to an electrolytic capacitor using a conductive polymer as a cathode electrolyte and a method for manufacturing the same. is there.

[0002]

2. Description of the Related Art Conventionally, an electrolytic capacitor using a valve metal such as aluminum or tantalum has a porous valve metal as an anode, an oxide of the valve metal as a dielectric layer, and a cathode as an electrolyte solution or an inorganic solid electrolyte. For example, in an aluminum electrolytic capacitor, an organic solvent containing an organic acid or the like has been used as a cathode, and in a tantalum electrolytic capacitor, manganese dioxide or the like has been used as a cathode. And it was common to provide the lead part connected to an anode and a cathode, respectively, and to form an exterior.

[0003] In response to digitization of circuits, high-frequency response of electronic components is required, and improvement of high-frequency response is also required for electrolytic capacitors by lowering resistance. Under such circumstances, use of a conductive polymer having good conductivity as a solid electrolyte for a cathode of an electrolytic capacitor has been studied and developed.

[0004] The method of forming a conductive polymer is roughly classified into an electrolytic oxidation polymerization method and a chemical oxidation polymerization method. In the former case,
A conductive polymer cannot be formed directly on an insulating oxide film by electrolytic oxidation polymerization. Therefore, a method has been proposed in which after a conductive precoat layer is formed on an oxide film in advance, a conductive polymer is formed on the oxide film by electrolytic oxidation polymerization using the precoat layer as an electrode. The latter is a method of forming a conductive polymer directly on an oxide film by chemical oxidative polymerization using a monomer oxidizing agent, and is widely used industrially because it is suitable for mass production.

[0005]

The electrolytic capacitor is characterized in that an oxide film is formed on the surface of pores of a porous valve metal body, and the oxide film is used as a dielectric layer. The remaining valve metal is used as the anode. Therefore, when a cathode electrolyte is formed in this capacitor, it is necessary to efficiently cover the surface of the pores of a very complicated porous body with a conductive polymer.

When a conductive polymer is formed as a cathode electrolyte by electrolytic oxidation polymerization, when a precoat layer having conductivity is formed in advance on an insulating oxide film, a porous material having a very complicated precoat layer is formed. Since it is difficult to form uniformly on the oxide film on the surface of the pores, as a result, the conductive polymer can be formed on the surface of the porous body but cannot be formed uniformly inside the pores. Also, when forming a conductive polymer on the pre-coat layer, it is difficult to uniformly introduce the solution down to the details of the very complicated porous pores. It has a disadvantage that it cannot be formed uniformly from the body surface to the pore details.

On the other hand, even when a conductive polymer is formed as a cathode electrolyte by the chemical oxidation polymerization method, it is difficult to introduce the solution into the pores inside the porous body, so that the conductive polymer is formed uniformly. There was a disadvantage that it could not be done.

That is, in both of the conventional electrolytic oxidation polymerization method and chemical oxidation polymerization method, it is possible to efficiently and uniformly form a conductive polymer even in the fine pores inside the porous body of the capacitor and to completely draw out the capacity. It was difficult. In order to solve this problem, before forming the conductive polymer, a surfactant layer is formed on the dielectric oxide film in advance, and the solution is easily introduced into the pore details, thereby facilitating the introduction into the pores. There has been proposed a method for improving the generation efficiency and homogeneity of the conductive polymer (Japanese Patent Laid-Open No. 3-64013). However, in this method, since the surfactant layer remains between the conductive polymer and the dielectric oxide film layer, the adhesion of the conductive polymer to the dielectric oxide film is low, and the formed conductive polymer There is an inherent problem that the capacity appearance rate is reduced due to the peeling off.

As described above, in both the electrolytic oxidation polymerization method and the chemical oxidation polymerization method, there remains a problem that the original capacity of the capacitor cannot be easily obtained.

[0010]

In order to achieve the above object, a method for manufacturing an electrolytic capacitor according to the present invention is characterized in that the anode is made of a porous material of a valve metal, and the dielectric layer is an oxide film layer of the valve metal. A method for producing an electrolytic capacitor in which the cathode electrolyte is a conductive polymer, wherein the conductive polymer is a conductive polymer obtained by chemically oxidizing and polymerizing a monomer in a solution. A method for producing an electrolytic capacitor, wherein the conductive polymer is formed inside and on the surface of a porous body by immersing a valve metal porous body having a dielectric layer formed therein in a solution containing the monomer and an oxidizing agent. When the valve metal porous body is immersed in the solution, the porous body is impregnated with the solution under reduced pressure. Thereby, the polymerization reaction solution can be uniformly impregnated to the entire pores inside the valve metal porous body, and the conductive polymer can be efficiently formed on the entire porous body pore surface.

Further, in the method for manufacturing an electrolytic capacitor according to the present invention, prior to immersion in the solution, the valve metal porous body is exposed to a solvent vapor of the solution or a solvent vapor having an affinity for the solution. And those in which the inner surface of the valve metal porous body pores is wetted with the solvent. As a result, the wettability of the polymerization reaction solution to the surface of the porous body pores is improved, and the entire pores inside the valve metal porous body can be quickly impregnated with the polymerization reaction solution, and the entire surface of the porous body pores is efficiently treated. A conductive polymer can be formed well.

Further, in the method for manufacturing an electrolytic capacitor according to the present invention, the method for forming the conductive polymer may be such that the method comprises forming the dielectric layer in a solution containing the monomer and a solution containing the oxidizing agent. In a method for manufacturing an electrolytic capacitor in which the conductive polymer is formed inside and on the surface of a porous body by alternately immersing the porous metal body, the valve metal porous body is immersed in the solution to be immersed first among the above solutions. Is characterized by impregnating the porous body with the solution under reduced pressure when immersing the porous body. With this, the same effect can be obtained, and the conductive polymer can be efficiently formed on the entire surface of the porous pores.

Further, in the method for manufacturing an electrolytic capacitor according to the present invention, when the valve metal porous body is immersed in the solution to be immersed first among the above solutions, the immersion of the solution to be immersed before the immersion is performed before the immersion. By exposing the valve metal porous body to a solvent vapor or a solvent vapor having an affinity for the solution, the inner surface of the valve metal porous body pores is wetted with the solvent. With this, the same effect can be obtained, and the conductive polymer can be efficiently formed on the entire surface of the porous pores.

Further, in the method for manufacturing an electrolytic capacitor according to the present invention, the method for forming a conductive polymer may include the step of forming a conductive pre-coat layer on a dielectric layer in advance in a solution containing the monomer. In a method for producing an electrolytic capacitor in which a porous metal is immersed and the conductive polymer is formed inside and on the surface of the porous body by oxidatively polymerizing a monomer using the precoat layer as an electrode, the valve metal porous material is contained in the solution. When the body is immersed and subjected to electrolytic oxidation polymerization, the porous body is impregnated with the solution under reduced pressure, and then subjected to electrolytic oxidation polymerization treatment. Prior to performing electrolytic oxidation polymerization by immersing the valve metal porous body in the solution,
By exposing the valve metal porous body to the solvent vapor of the solution or the vapor of a solvent having an affinity for the solution, the inner surface of the valve metal porous body pores (precoat layer surface) is wetted with the solvent. Including things. Thus, in each case, the same effect is obtained, and the conductive polymer can be efficiently formed on the entire surface of the porous pores.

Further, the present invention includes an electrolytic capacitor manufactured by the above-described manufacturing method. As described above, in any of the methods, the conductive polymer can be efficiently and uniformly formed not only on the surface of the valve metal porous body but also on the inside thereof. In addition, when manufactured by this manufacturing method, a foreign substance such as a surfactant layer is not interposed between the conductive polymer and the dielectric oxide film. Has good adhesion. As a result, a capacitor having a high capacitance appearance rate can be manufactured efficiently.

Further, the present invention includes an electrolytic capacitor manufactured by using the above-described manufacturing method, whereby a high-capacity electrolytic capacitor can be provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the electrolytic capacitor of the present invention, the anode is a valve metal porous body, and the valve metal is preferably aluminum or tantalum. The valve metal porous body has a large number of fine holes or pores communicating with the outer surface.

As an example of the anode, for example, in the case of aluminum, a porous body obtained by forming a large number of small holes by etching an aluminum foil and then winding the aluminum foil, or in the case of tantalum, After compression molding from tantalum powder, it is sintered to form a porous body.

The dielectric layer uses a thin oxide film of the metal formed on the surface of the metal by anodic oxidation, and is also formed on the surface of a large number of fine holes in the porous body.

In the present invention, a conductive polymer material is used for the cathode electrolyte, and the conductive polymer is formed on the dielectric oxide film. The conductive polymer is not particularly limited, but preferably, a conductive polymer of a heterocyclic five-membered ring compound or a derivative thereof is used. Examples of the heterocyclic five-membered ring polymer that can be used for the conductive polymer include pyrrole, thiophene, 3-alkylthiophene, and isothianaphthene.

In the polymerization from a monomer, in the present invention, an electrolytic oxidation polymerization method and a chemical oxidation polymerization method are used. In the chemical oxidative polymerization method, a monomer is reacted with an oxidizing agent to form a conductive polymer. The oxidizing agent used individually includes hydrogen peroxide, other peroxides, and trivalent iron ions. Are preferably used.

In the chemical oxidation polymerization method, the conductive polymer is formed by removing the valve metal porous body on which the dielectric layer has already been formed,
By dipping and holding in a solution containing a monomer to be a conductive polymer and an oxidizing agent for polymerization, the monomer is polymerized by the oxidizing agent, and the conductive polymer is formed on the valve metal porous dielectric. (Hereinafter abbreviated as one-component chemical oxidative polymerization). Alternatively, the monomer is oxidized by alternately immersing the valve metal porous body on which the dielectric layer is already formed in a solution containing a monomer to be a conductive polymer and a solution containing an oxidizing agent for oxidative polymerization. The polymer is polymerized by the agent to form a conductive polymer on the valve metal porous dielectric (hereinafter abbreviated as a two-part chemical oxidation polymerization method).

In the electrolytic oxidation polymerization method, a conductive polymer is formed by forming a pre-coat layer made of manganese dioxide, a conductive polymer, or the like on a dielectric film of a valve metal porous body on which a dielectric layer has already been formed. Thereafter, the valve metal porous body is immersed in a solution containing the monomer, and the monomer is electrolytically oxidized and polymerized using the precoat layer as an electrode in the solution to form a conductive material on the precoat layer on the valve metal porous dielectric. A polymer is formed.

In any of the methods for forming a conductive polymer, a solution for impregnating the valve metal porous body (a mixed solution of a monomer and an oxidizing agent in the one-component chemical oxidation polymerization method and an alternating solution in the two-component chemical oxidation polymerization method) is used. The valve metal porous body is immersed in the solution that is immersed first in the solution immersed in the solution, or the monomer solution in the electrolytic oxidation polymerization method. Is preferably impregnated. Repeat this operation one or more times,
By sufficiently forming the conductive polymer on the dielectric film, the conductivity of the dielectric oxide film from the surface of the porous body to the details of the pores can be reduced compared to the conventional method of forming a conductive polymer without decompression treatment. The coverage by the conductive polymer is improved. As a result, in the conventional method, only about 70 to 80% of the design capacity of the porous body can be extracted, whereas in the manufacturing method of the present invention, the capacitance appearance rate is improved by 10% or more, and 90% or more of the design capacity. Of capacity. In addition, in the case of a conventionally proposed method of interposing a surfactant layer, a capacity appearance rate of 90% or more can be achieved initially, but the conductive polymer peels off from the dielectric film by heat treatment or the like, The capacity appearance rate may decrease to about 60 to 70%. On the other hand, in the case of the electrolytic capacitor according to the manufacturing method of the present invention, even if heat treatment or the like is performed, the decrease in capacity is relatively small, and the capacity appearance rate can be secured to 80% or more.

Also, preferably, a method of wetting the dielectric oxide film of the valve metal porous body with the solvent vapor of the solution or the vapor of the solvent having an affinity for the solution can be adopted. As a result, the affinity between the dielectric oxide film and the solution is increased, and the solution easily penetrates into the deep part of the pores, so that a conductive polymer can be formed on the entire dielectric film. As this solvent, for example, water can be used if the reaction solution system is an aqueous solution system, and when impregnating with a solution containing a monomer, various organic solvents can be used because of its high affinity with the monomer. In some cases, a method of wetting with monomer vapor can also be used. Furthermore, even when the conductive polymer forming operation is repeatedly performed, by performing the wetting operation, the affinity of the solution on the conductive polymer previously formed is increased, and the solution is extended to the deep portion of the pores. It easily penetrates and a sufficient amount of conductive polymer can be easily formed on the entire dielectric film. As a result, as compared with the conventional conductive polymer forming method, the coverage of the dielectric oxide film with the conductive polymer is improved, and the same effect as the above-described method is obtained. We can draw capacity.

In the formation of the precoat layer in the case of the electrolytic oxidation polymerization method, the above-described vacuum impregnation method and solvent wetting method can be adopted. In particular, when the precoat layer is a conductive polymer layer, the precoat layer is subjected to one or several treatments using the two chemical oxidation polymerization methods of the present invention to cover the precoat layer from the surface of the porous body to the fine pores. It can be formed uniformly on the dielectric oxide film, and then the conductive polymer can be easily formed on the entire dielectric film by forming the conductive polymer on the precoat layer by electrolytic oxidation polymerization. Become. As a result, it is possible to suppress a decrease in the capacity appearance rate due to the inhomogeneity of the precoat layer, and to stably reproduce the capacity appearance rate of 90% or more by the method of the present invention.

Here, the degree of reduced pressure in the reduced pressure impregnation method is not particularly limited as long as the pressure is within the atmospheric pressure or lower and the solvent does not boil.

The vapor pressure of the solvent used for wetting is not particularly limited, but it is preferable to control the vapor pressure so that dew does not form on the surface or inside of the solvent.

[0029]

EXAMPLE In this example, polypyrrole was used as the conductive polymer, tantalum was used as the valve metal of the porous body of the capacitor, and the two-component chemical oxidation polymerization method was used as the method of forming the conductive polymer.

1 and 2 show an outline of a method for manufacturing an electrolytic capacitor according to an embodiment of the present invention.

The tantalum powder is molded and fired together with the leads to form a porous body of 1.4 mm × 3.0 mm × 3.8 mm, and then the surface of the pores of tantalum is formed in a phosphoric acid aqueous solution at a formation voltage of 30 V. An oxide film dielectric layer was formed to obtain a porous capacitor element.

The monomer solution was prepared by dissolving pyrrole as a monomer for forming polypyrrole at a concentration of 0.1 mol / l in an aqueous solution containing 10 vol% of isopropyl alcohol.

The oxidizing agent solution is prepared by adding 0.1 mol / l of iron (III) sulfate as an oxidizing agent to an aqueous solution containing 10 vol% of isopropyl alcohol, and alkylnaphthalenesulfonic acid ions as other additives in the form of Na salt. 0.
It was prepared by dissolving it at a concentration of 05 mol / l.

On the dielectric layer of the prepared capacitor element,
A conductive polymer was formed by the following chemical oxidation polymerization method to form a cathode, and a lead plate as a current collector for the cathode was provided outside to form an electrolytic capacitor, and the capacitance at 120 Hz was measured.

(1) The capacitor element is immersed in a monomer solution, then immersed in an oxidizing agent solution, and a conductive polymer is polymerized on the dielectric oxide film on the surface of the capacitor element porous body and in the pores, and is washed. And drying. This operation was repeated 20 times to form a sufficient amount of the conductive polymer on the capacitor element.

(2) After the capacitor element was immersed in the monomer solution, the pressure of the entire solution was reduced to 0.2 atm. Thereafter, the resultant was immersed in an oxidizing agent solution to polymerize and form a conductive polymer on the surface of the capacitor element porous body and on the dielectric oxide film inside the pores, followed by washing and drying. Further, the pressure reduction and polymerization operations were repeated 20 times to form a sufficient amount of the conductive polymer on the capacitor element.

(3) The capacitor element was left at room temperature in a saturated vapor pressure of ethanol for 2 minutes to wet the surface of the porous body and the inner surface of the pores with ethanol vapor. Thereafter, the resultant was immersed in a monomer solution and further immersed in an oxidizing agent solution to polymerize and form a conductive polymer on the surface of the capacitor element porous body and on the dielectric oxide film inside the pores, followed by washing and drying. In addition, this wetting and polymerization operation is
This was repeated twice to form a sufficient amount of the conductive polymer on the capacitor element.

(4) In order to treat a surfactant on the dielectric oxide film of the capacitor element, the capacitor element was immersed in an aqueous solution of an alkyl phosphate as a surfactant, pulled up and dried. Thereafter, a sufficient amount of conductive polymer was formed on the capacitor element in the same manner as in (1).

Table 1 shows the value of the capacitance at 120 Hz of the electrolytic capacitor manufactured as described above.

[0040]

[Table 1]

As is clear from Table 1, the capacitance of the electrolytic capacitor in which the conductive polymer was formed by the methods (2) and (3) of the present invention was compared to the conventional example (1). Increased spawn rate. The capacitance after cooling at 150 ° C. for 1 hour is also shown in Table 1. However, compared to the conventional example (4), the methods (2) and (3) according to the production method of the present invention were compared. In the case where the conductive polymer was formed, a decrease in capacity was small and good characteristics could be maintained.

As described above, according to the production method of the present invention, the coverage of the dielectric oxide film with the conductive polymer can be easily improved, and the adhesion to the dielectric film can be maintained high. Therefore, a high-capacity electrolytic capacitor can be stably provided.

In this embodiment, an example in which the two-component chemical oxidation polymerization method is used is shown. However, the same effect was obtained in the one-liquid chemical oxidation polymerization method and in the electrolytic oxidation polymerization method. .

In this embodiment, an example in which pyrrole is used as a monomer is shown, but the type is not limited as long as it is polymerized into a conductive polymer.

Further, in this example, the effect was confirmed by setting the pressure at the time of impregnating the solution under reduced pressure to 0.2 atm. However, the pressure range is not particularly limited as long as the solution does not boil below the atmospheric pressure. Not something.

Further, in this example, the wet treatment was carried out with ethanol vapor, but the same effect was confirmed with the solvent vapor of the solution to be impregnated or various solvent vapors having an affinity for the solution.

When the capacitor element is alternately immersed in the oxidizing agent solution and the monomer solution, it does not matter which of the oxidizing agent solution and the monomer solution is immersed first.

In this embodiment, a tantalum electrolytic capacitor is described, but the present invention can be similarly applied to an aluminum electrolytic capacitor.

[0049]

As described above, according to the present invention, the coverage of the dielectric oxide film with the conductive polymer is improved by using the reduced pressure impregnation method during the solution impregnation, and the capacitance appearance rate is increased. An excellent electrolytic capacitor can be provided.

According to the present invention, prior to the impregnation of the solution, the surface of the porous pores is wetted with the solvent vapor of the solution or a solvent vapor having an affinity for the solution in advance.
It is possible to improve the coverage of the dielectric oxide film with the conductive polymer and provide an excellent electrolytic capacitor having a high capacitance appearance rate.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a method for manufacturing an electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a method for manufacturing an electrolytic capacitor according to an embodiment of the present invention.

Claims (10)

[Claims] 1. A method for manufacturing an electrolytic capacitor in which an anode is formed of a valve metal porous body, a dielectric layer is an oxide film layer of the valve metal, and a cathode electrolyte is a conductive polymer. The molecule is a conductive polymer formed by chemically oxidizing and polymerizing a monomer in a solution.
A method for manufacturing an electrolytic capacitor, wherein the conductive polymer is formed inside and on the surface of a porous body by immersing a valve metal porous body having a dielectric layer in a solution containing the monomer and the oxidizing agent, The method of manufacturing an electrolytic capacitor, wherein the method of forming the conductive polymer comprises, when immersing the porous valve metal body in the solution, impregnating the porous body with the solution under reduced pressure. 2. The method of manufacturing an electrolytic capacitor, wherein the anode is made of a valve metal porous material, the dielectric layer is an oxide film layer of the valve metal, and the cathode electrolyte is a conductive polymer. The molecule is a conductive polymer formed by chemically oxidizing and polymerizing a monomer in a solution.
A method for manufacturing an electrolytic capacitor, wherein the conductive polymer is formed inside and on the surface of a porous body by immersing a valve metal porous body having a dielectric layer in a solution containing the monomer and the oxidizing agent, The method of forming the conductive polymer, prior to immersion in the solution, by exposing the valve metal porous body to a solvent vapor of the solution or a solvent vapor having an affinity for the solution,
A method for producing an electrolytic capacitor, comprising wetting the inner surface of a porous valve metal body with the solvent. 3. The method of manufacturing an electrolytic capacitor, wherein the anode comprises a valve metal porous body, the dielectric layer is an oxide film layer of the valve metal, and the cathode electrolyte is a conductive polymer. The molecule is a conductive polymer formed by chemically oxidizing and polymerizing a monomer in a solution.
In the solution containing the monomer and the solution containing the oxidizing agent,
The method of manufacturing an electrolytic capacitor, wherein the conductive polymer is formed inside and on the surface of the porous body by alternately immersing the valve metal porous body having the dielectric layer formed thereon, wherein the conductive polymer is formed. A method for producing an electrolytic capacitor, characterized in that, when immersing a valve metal porous body in a solution to be immersed first among the above-mentioned solutions, the solution is impregnated in the porous body under reduced pressure. 4. The method of manufacturing an electrolytic capacitor, wherein the anode comprises a valve metal porous body, the dielectric layer is an oxide film layer of the valve metal, and the cathode electrolyte is a conductive polymer. The molecule is a conductive polymer formed by chemically oxidizing and polymerizing a monomer in a solution.
In the solution containing the monomer and the solution containing the oxidizing agent,
The method of manufacturing an electrolytic capacitor, wherein the conductive polymer is formed inside and on the surface of the porous body by alternately immersing the valve metal porous body having the dielectric layer formed thereon, wherein the conductive polymer is formed. In the method, when the valve metal porous body is immersed in the solution to be immersed first among the above solutions, prior to immersion in the solution to be immersed before, the solvent vapor of the solution to be immersed first or the affinity to the solution is applied. A method for manufacturing an electrolytic capacitor, comprising exposing a porous body of a valve metal to vapor of a solvent having a property to wet the inner surface of the pores of the valve metal porous body with the solvent. 5. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the operation of forming the conductive polymer is repeated one or more times. 6. A method for manufacturing an electrolytic capacitor in which an anode is made of a valve metal porous body, a dielectric layer is an oxide film layer of the valve metal, and a cathode electrolyte is a conductive polymer. The molecule is a conductive polymer obtained by electrolytically oxidizing and polymerizing a monomer in a solution.
In a solution containing the monomer, a valve metal porous body in which a pre-coat layer having conductivity is formed in advance on a dielectric layer is immersed, and the monomer is oxidized and polymerized using the pre-coat layer as an electrode to form the inside and the surface of the porous body. In a method for manufacturing an electrolytic capacitor that forms a conductive polymer, the method for forming a conductive polymer includes immersing a valve metal porous body in the solution and performing electrolytic oxidative polymerization. A method for producing an electrolytic capacitor, comprising: performing impregnation under reduced pressure followed by electrolytic oxidation polymerization treatment. 7. A method for manufacturing an electrolytic capacitor in which an anode is made of a valve metal porous body, a dielectric layer is an oxide film layer of the valve metal, and a cathode electrolyte is a conductive polymer. The molecule is a conductive polymer obtained by electrolytically oxidizing and polymerizing a monomer in a solution.
In a solution containing the monomer, a valve metal porous body in which a pre-coat layer having conductivity is formed in advance on a dielectric layer is immersed, and the monomer is oxidized and polymerized using the pre-coat layer as an electrode to form the inside and the surface of the porous body. In a method for producing an electrolytic capacitor that forms a conductive polymer, the method for forming the conductive polymer is performed before immersing the valve metal porous body in the solution to perform electrolytic oxidation polymerization. A method for manufacturing an electrolytic capacitor, comprising exposing a valve metal porous body to a solvent vapor or a solvent vapor having an affinity for the solution to wet the inner surface of the valve metal porous body pores with the solvent. 8. The method for manufacturing an electrolytic capacitor according to claim 6, wherein the precoat layer is made of a conductive polymer, and the forming method is the method according to any one of claims 1 to 4. 9. The method according to claim 1, wherein the valve metal is aluminum or tantalum. 10. An electrolytic capacitor manufactured by using the manufacturing method according to claim 1.