JP3416050B2 - Electrolytic capacitor and method of manufacturing the same - Google Patents

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 manufacturing method thereof, and more particularly to an electrolytic capacitor using a conductive polymer layer as a cathode and a manufacturing method thereof. .

[0002]

2. Description of the Related Art Conventionally, an electrolytic capacitor using a valve metal such as aluminum or tantalum has a valve metal porous body as an anode element and an oxide film of the valve metal as a dielectric layer, which serves as a pore surface of the porous body and the outside. It was general to form an exterior by forming it on the surface and using an electrolyte solution or an inorganic solid electrolyte for the cathode, providing lead portions respectively connected to the anode and the cathode. 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.

In recent years, high frequency response of electronic parts has been required in response to digitalization of circuits, and improvement of high frequency response by lowering resistance of electrolytic capacitors is also required. Under such circumstances, the use of a conductive polymer compound having a high conductivity as a solid electrolyte for a cathode of an electrolytic capacitor has been studied and developed.

Generally, a conductive polymer is formed as a conductive polypyrrole or polythiophene by polymerizing a monomer such as pyrrole or thiophene by an electrolytic oxidative polymerization method or a chemical oxidative polymerization method. In addition, a dopant anion is generally coordinated in order to further improve the electron conductivity of the conductive polymer, and the monomer is generally polymerized in a solution in which the dopant coexists.
Various anions (chlorine ion, sulfate ion, organic acid ion, etc.) are used as this dopant, but industrially, the steric hindrance is large in order to suppress dedoping from the conductive polymer layer after formation. Organic acid-based anions having a molecular structure that does not easily move in the polymer are often used.

As a structural feature of the electrolytic capacitor, an oxide film is formed on the surface of the pores of the porous valve metal, the oxide film serves as a dielectric layer, and the valve metal remaining in the core serves as an anode. Therefore, when forming a cathode on this porous body, it is necessary to efficiently cover the pore surface of the extremely complicated porous body with the conductive polymer layer. In this respect, when the electrolytic oxidation polymerization method is used, a conductive polymer layer is formed in a dense film form, and the film itself has low resistance and high quality, but the pores inside the porous body are Up to this point, the conductive polymer is not sufficiently formed, and there is a drawback that the original capacity cannot be drawn out due to the insufficient coverage of the dielectric layer.

On the other hand, the chemical oxidative polymerization method is often industrially used because it has a feature that a conductive polymer can be easily formed up to the pores inside the porous body. Generally, in a chemical oxidative polymerization method, as shown in US Pat. No. 4,691,001, a conductive polymer is formed by a reaction between a monomer and an oxidizing agent for polymerization. Therefore, the formation speed depends on the collision probability of both. When the substrate for forming the conductive polymer, such as a capacitor, is a porous body, in general, alternate immersion of a monomer solution and an oxidant solution causes one of the substrates to be contained in the pores to contact the other. Then, a method of polymerizing a conductive polymer in the pores is performed. Also,
In some cases, a method of impregnating a porous body with a solution containing both a monomer and an oxidizing agent to polymerize and generate a conductive polymer inside the pores of the porous body is also adopted.

[0007]

However, since the rate of formation of the conductive polymer depends on the collision probability of the monomer and the oxidizing agent, that is, the existence probability thereof, the chemical oxidation polymerization method is used to oxidize the monomer liquid and the oxidizing agent. When a conductive polymer is formed by alternate immersion in a chemical solution, the rate of formation of the conductive polymer on the pore surface near the deep pores and the center of the porous body is It becomes much slower than the formation of the polymer, and it takes a very long time or number of treatments to completely cover the inside with the conductive polymer layer and bring out the original capacity.
In some cases, the pore passages communicating with the outer surface of the porous body are first closed by the conductive polymer layer, and as a result, there is a problem in that the conductive polymer layer cannot be uniformly coated to the deep portion and the central portion. It was

Further, when a conductive polymer is formed by a chemical oxidative polymerization method by alternately immersing a monomer liquid and an oxidant solution, the conductive polymer is reacted and formed inside the pores of the capacitor element porous body. At this time, the previously impregnated liquid (monomer solution or oxidant solution) also flows out into the reaction tank outside the porous body, and the conductive polymer is formed in the reaction tank as well, so that the capacitor porous body is electrically conductive in good yield. It was difficult to form a conductive polymer layer.

Further, in the method of impregnating the reaction solution containing both the monomer and the oxidizing agent into the porous body, the polymerization reaction is started from the time when the reaction solution is prepared, and the solution is kept while maintaining sufficient reaction activity inside the porous body. Since it is difficult to introduce it, there has been a problem that the central part and the deep part of the pores cannot be uniformly coated with the conductive polymer layer. Furthermore, the biggest problem is that the prepared reaction solution has a short activation time, which makes it difficult to store and is not industrially suitable.

On the other hand, by lowering the concentration of the reaction solution to reduce the reaction rate, the reaction activity can be maintained for a long time, and the conductive polymer layer can be formed to some extent in the central portion of the porous body and the details. Although it can be formed and can be stored for a certain period of time, the amount of conductive polymer formed per reaction is small and it is possible to completely cover the inside with the conductive polymer layer and fully extract the original capacity. Requires a very large number of processing times. As described above, even in the chemical oxidative polymerization method, it is difficult to efficiently form the conductive polymer layer even in the pores inside the capacitor porous body and bring out the designed capacity completely.

The object of the present invention is to solve the above problems, to form the conductive polymer even in the pores inside the porous body of the capacitor with high yield and efficiency, and to easily achieve the target capacity. An object is to provide a method and an electrolytic capacitor having a high capacity achievement rate.

[0012]

In order to achieve the above object, a method of manufacturing an electrolytic capacitor according to the present invention comprises an anode made of a valve metal, a dielectric layer made of an oxide layer of the valve metal on the anode surface, A method for producing an electrolytic capacitor comprising a cathode comprising a conductive polymer layer formed on the surface of a dielectric layer, wherein the conductive polymer layer is a solution containing an oxidizing agent and a dopant capable of polymerizing the monomer. In particular, the present invention relates to a method for forming a conductive polymer by a chemical oxidative polymerization method in the reaction tank outside the porous body, and a method for increasing the amount of the conductive polymer deposited inside and on the surface of the porous body. It is about.

The feature is that in the first method, the method for forming the conductive polymer layer is such that the dielectric substance is added to a solution containing a monomer, an oxidant and a dopant, the reaction rate of which is kept slow. By immersing the valve metal porous body on which a layer is formed, and then immersing the porous body in the solution, the temperature inside the porous body or inside the porous body is made higher than the solution temperature outside the porous body, thereby That is, the polymerization reaction of (1) is made faster than the external polymerization reaction to preferentially form the conductive polymer layer on the dielectric layer inside the porous body.

[0014]

Further, preferably, in the above-mentioned method, as a heating method for keeping the temperature of the porous body at a temperature higher than the solution temperature, the lead portion connected to the inside of the porous body is heated as a heat conducting medium. Is.

As a third method, according to the present invention, in the method of forming a conductive polymer, at least after the valve metal porous body on which the dielectric layer is formed is previously housed in a reaction element case. A monomer solution containing a dopant in either one of them and an oxidant solution are injected into the element case for reaction before or after the reaction activity is lowered at the same time or after mixing, thereby keeping the activity of the reaction solution high. The solution is sufficiently impregnated into the porous body to form the conductive polymer layer, and at the same time, the reaction space is limited by providing the element case for the reaction, and the amount of the conductive polymer formed outside the porous body portion is reduced. Including things.

Further, when at least one of the dopants is an organic acid type dopant, preferably, when forming a conductive polymer layer on the porous body, first, as a pretreatment, an organic acid type dopant is not included. A conductive polymer layer is formed on the dielectric layer inside the porous body, and then, as the main treatment, the conductive polymer layer containing an organic acid dopant is formed on the layer. Including those formed by any one of the three methods.

Further, the method for producing an electrolytic capacitor according to the present invention is a simpler method for forming a conductive polymer layer, in which either one of the above-mentioned first and second methods is applied as a pretreatment in advance. After forming a conductive polymer layer containing a dopant on the dielectric layer near the center of the porous body, a conductive polymer layer containing a dopant was formed by the above-mentioned pretreatment by a conventional alternate dipping method or the like as the main treatment. It is further formed on the conductive polymer layer.

When at least one of the dopants is an organic acid-based dopant, it contains a monomer and an oxidant as a polymerization reaction solution when performing any one of the above-mentioned first and second methods as a pretreatment. After forming a conductive polymer layer containing no organic acid type dopant on the dielectric layer by the above heating method using a solution containing no organic acid type dopant, the conventional alternating dipping method is used as the main treatment. The conductive polymer layer containing the organic acid type dopant is formed on the conductive polymer layer containing no organic acid type dopant.

Further, when at least one of the dopants is an organic acid-based dopant, the present invention provides a method of pre-treating either of the first and second methods described above. As a pretreatment of 1, the conductive polymer layer containing no organic acid dopant is prepared by the above heating method using a solution containing a monomer and an oxidizing agent as a polymerization reaction solution and containing no organic acid dopant. After being formed on the body layer, a solution containing a monomer, an oxidizing agent, and an organic acid-based dopant as a polymerization reaction solution is used as a second pretreatment, and a high conductivity containing an organic acid-based dopant is obtained by the heating method described above. After the molecular layer is formed on the conductive polymer layer containing no organic acid dopant formed in the first pretreatment, the organic acid dopant is added by the conventional alternate dipping method as the main treatment. The conductive polymer layer further include those formed on the conductive polymer layer containing the organic acid-type dopant.

The present invention also includes an electrolytic capacitor formed by using the above manufacturing method.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the electrolytic capacitor of the present invention, the anode is a porous body of valve metal, the dielectric layer is an oxide layer of valve metal, and the cathode is a conductive polymer layer containing a dopant. Is. In the present invention, the anode has a large number of pores or pores communicating with the outer surface inside the porous body of the valve metal, and the anode surface area is remarkably expanded. For example, aluminum or tantalum is preferably used. The dielectric layer is a very thin oxide film formed on the surface of the anode including the surface of pores inside the porous body.

The conductive polymer layer, including the internal voids, is deposited on the dielectric layer to serve as a cathode. The conductive polymer layer forming the cathode is formed by a chemical oxidative polymerization method in a solution containing a monomer that is a polymerizable oxidant and a dopant. The monomer is selected from those exhibiting conductivity, and for example, among heterocyclic 5-membered ring compounds, pyrrole, thiophene, 3-alkylthiophene, isothianaphthene, etc. are preferably used.

The solution used for the polymerization comprises the above-mentioned monomer which is a component of the conductive polymer, an oxidizing agent for the polymerization (for example, hydrogen peroxide, ferric ion such as iron (III) sulfate) and the like. Furthermore, in the case of including a dopant, the term "dopant" is included.

The dopant is added to further increase the conductivity of the conductive polymer. As the inorganic acid-based dopant, various anions such as chloride ion and sulfate ion can be used, but the inorganic-acid-based dopant is likely to escape by elution into water in the treatment after formation. Therefore, for the purpose of suppressing dedoping from the conductive polymer layer, it is preferable to use an organic acid-based anion having a molecular structure that has a large steric hindrance and is hard to move in the polymer.
In particular, for the above-mentioned conductive polymer, it is preferable to use an aryl sulfonate ion such as an alkylnaphthalene sulfonate or an aryl phosphonate ion.
It can be added to the solution in the form of salt or other alkali salt.

In the first manufacturing method, the valve metal porous body on which a dielectric layer has been formed in advance is immersed in this solution, and the temperature of the porous body or the inside of the porous body is kept as it is for a certain period of time. It holds something higher. By this method, only the reaction rate of chemical oxidative polymerization of the monomer impregnated in the pores of the porous body is made faster than the external polymerization reaction rate,
It promotes the formation of polymer in the pores.

According to the above method, the conductive polymer layer in the surface layer portion of the porous body is conventionally very fast, and the conductive polymer layer in the inner pores is not sufficiently formed. Only about 70% of the capacity expected from the total area of the surface of the body and the surface of the internal pores was achieved. However, according to the production method of the present invention, high conductivity inside the porous body is obtained. The formation speed of the molecular layer is accelerated more than that of the surface layer, and sufficient coverage of the dielectric layer can improve the capacity achievement rate of the capacitor to about 90%.

In the second method, a method of forming a conductive polymer layer by a chemical oxidative polymerization method is a porous valve metal body in which the dielectric layer is formed in a solution containing a monomer, an oxidizing agent and a dopant. Alternatively, the porous body may be immersed in the solution to impregnate the inside of the porous body with the solution, and then the porous body may be pulled out of the solution and maintained at a temperature higher than the solution temperature to accelerate the polymerization reaction.

According to this method, the monomer retained in the pores of the porous body can be efficiently polymerized in the pores without flowing out, and the polymer can be sufficiently filled. The coating can achieve capacities as high as 90%. At this time, a temperature difference from that at the time of pulling may be provided by cooling the temperature of the solution to be immersed, or a temperature difference from that at the time of immersion may be provided by forcibly heating the element temperature at the time of pulling, or You may go both. In particular, when the element is forcibly heated by any of the first and second methods, a method of heating the lead portion communicating with the inside of the porous body is preferable. For example, as shown in FIG. 1, in the case of a structure in which the lead 2 is embedded in the porous body 1 in advance and the other end is projected from the surface 10, the structure is soaked as described above and then led to the inside of the porous body. Heating is performed through the protruding leads 2. In this case, the buried lead 2
The conductive polymer forming reaction is promoted from the vicinity of, ie, the central portion 11 of the porous body, and the inner coatability is further improved.

Further, in the second method, since the porous body is impregnated with the solution and then pulled up, the volatilization of the solvent is accelerated. Therefore, the formation of the conductive polymer is performed in the solvent vapor, but the drying speed of the solvent can be slowed and the inhibition of the formation of the conductive polymer due to the solvent drying can be suppressed. At this time, it is preferable that the vapor partial pressure of the solvent vapor is 70% or more of the saturated vapor pressure of the solvent at the holding temperature, and the effect is sufficiently observed.

In the first production method described above, the temperature inside the porous body is kept higher than the solution temperature outside the porous body by 10 ° C. or more, so that the reaction inside the porous body is about twice or more than the reaction outside. It is preferable that the reaction rate is By controlling the reaction rate in this manner, the conductive polymer can be efficiently deposited inside the porous body.

In the second method, in order to promote the polymerization reaction by heating after raising the porous body to efficiently polymerize the monomer, it is desirable that the reaction does not occur in the dipping solution. However, in order to suppress the reaction almost completely, it is necessary to lower the temperature to about -40 ° C or lower, which is industrially impossible. Therefore, assuming that the solution is used up in about 1 hour, in order to use about 90%,
It is preferable to control the polymer deposition weight per hour to 10% or less with respect to the blended monomer weight. For this purpose, it is preferable to determine the concentrations of the monomer and the oxidant in the solution and keep the temperature of the solution low. By regulating the polymer deposition rate in the solution in this way,
The efficiency of polymer precipitation inside the porous body can be effectively increased.

In the third manufacturing method, the conductive polymer is formed by a chemical oxidative polymerization method, after the valve metal porous body on which the dielectric layer is formed is previously housed in a reaction element case, A monomer solution containing at least one of the dopants and an oxidant solution are injected into the device case at the same time or after mixing and before the reaction activity decreases. By this method, the reaction space can be limited, and the weight ratio of the polymer attached to the porous material with respect to the weight of the charged monomer is improved as compared with the case where there is no case, and the conductive polymer is deposited on the dielectric film in good yield. Can be formed. And, while keeping the activity of the reaction solution high, the solution can be sufficiently impregnated inside the porous body,
The conductive polymer layer can be efficiently formed inside the pores of the porous body and inside the pores in the vicinity of the center, and sufficient capacity of the dielectric layer can achieve a capacity of about 90%.

In the above-mentioned third method, when the monomer solution and the oxidant solution are injected into the element case for reaction after mixing rather than simultaneously injecting, the conductive polymer is homogeneously formed inside the porous body. However, if both are mixed in advance, the reaction activity decreases until the reaction solution reaches the inside of the porous body sufficiently. Therefore, the reaction is controlled so that the weight of the polymer deposited before mixing and injecting the monomer solution and the oxidant solution into the element case for reaction is 10% or less of the charged monomer weight, or the time until injection after mixing is shortened. It is preferable to control the porosity, whereby the reaction solution can be impregnated while retaining the reaction activity even in the deep part and the central part of the porous body, and the conductive polymer can be efficiently deposited inside the porous body. This reaction control may be performed by keeping the monomer solution and the oxidant solution at a low temperature, or by reducing the concentration of each solution, but in order to increase the amount of polymer formation per reaction, ,
It is preferable to keep the temperature low.

In the third manufacturing method, after the monomer solution and the oxidizing agent solution are impregnated into the porous body, the reaction is promoted by keeping the porous body at a temperature higher than the temperature of the injected solution to accelerate the reaction. It is possible to reduce the processing time for forming the. At this time, as a method of maintaining high temperature,
A method of heating via a metal lead that communicates with the inside of the anode can be preferably adopted, whereby the coverage of the dielectric layer inside with the conductive polymer can be further improved, and the capacity achievement rate can be improved. Further, in the third manufacturing method, the conductive polymer on the dielectric film of the porous body is made to account for the total weight of the polymer by setting the internal volume of the element case for reaction to be more than 1 time and not more than 4 times the size of the porous body. The formed amount ratio can be 20% or more, and the yield can be improved.

Further, when at least one of the dopants is an organic acid type dopant, a conductive polymer containing no organic acid type dopant is first treated as a pretreatment when the conductive polymer layer is formed by the chemical oxidative polymerization method. The layer is preferably preformed by a chemical oxidative polymerization method. The conductive polymer layer containing the organic acid dopant has low adhesion to the dielectric layer and the film is not dense, but the conductive polymer layer containing no organic acid dopant is a dense and homogeneous film. As a result, it can be formed with good adhesion on the surface of the dielectric layer including the inside of the pores, and has high adhesion with the polymer layer containing the above-mentioned organic acid-based dopant formed thereafter. Therefore, the above-mentioned first, second and third methods are used as the main treatment, and a conductive polymer layer containing an organic acid type dopant is formed on the conductive polymer layer containing no organic acid type dopant in the above liquid. It is formed by a heating method, a pull-up heating method, or a liquid injection method into the reaction element case. As a result, the coverage of the dielectric layer can be increased up to the inside of the pores of the valve metal porous body,
Moreover, it is possible to form a conductive polymer film that is dense and has high adhesion to the dielectric layer. By the method including such pretreatment, it is possible to obtain a capacitor having a very high capacity achievement rate, low resistance, and good frequency characteristics. On this occasion,
The dopant other than the organic acid type may or may not be included in the pretreatment.

Furthermore, when forming the conductive polymer layer by the chemical oxidative polymerization method, first, as a pretreatment, the above-mentioned heating method is adopted to form the conductive polymer layer containing the dopant by the chemical oxidative polymerization method. After forming and improving the coverage of the pores inside the porous valve metal porous body with the conductive polymer layer on the surface of the dielectric layer, as the main treatment, the conductivity including the dopant is obtained by the conventional alternate dipping method or the like. A method of further forming a polymer layer is also adopted. This makes it possible to easily form a valve metal porous body having a high coverage with a conductive polymer from the inside to the surface of the porous body, and to easily obtain a capacitor having a high capacity achievement rate.

Furthermore, when at least one of the dopants is an organic acid type dopant, the above-mentioned heating method is first applied as a pretreatment when forming the conductive polymer layer by the chemical oxidative polymerization method. After forming a conductive polymer layer containing no organic acid type dopant on the surface of the body layer by a chemical oxidative polymerization method, a conductive polymer layer containing an organic acid type dopant is formed by a conventional alternate dipping method as the main treatment. A forming method can also be adopted. As a result, a conductive polymer film having a high coverage with the conductive polymer inside the pores up to the vicinity of the central portion of the porous valve metal porous body and having high adhesion with the dielectric layer is formed on the dielectric layer. Therefore, it is possible to easily obtain a capacitor having a high capacity achievement rate and good frequency characteristics and good quality.

When at least one of the dopants is an organic acid-based dopant, the above-mentioned heating method is used as the first pretreatment when forming the conductive polymer layer by the chemical oxidative polymerization method. After the conductive polymer layer containing no organic acid dopant is formed on the surface of the dielectric layer by the chemical oxidative polymerization method, the above-mentioned heating method is applied as the second pretreatment. After forming a conductive polymer layer containing an organic acid-based dopant on the body layer surface by a chemical oxidative polymerization method,
As the main treatment, a method of further forming a conductive polymer layer containing an organic acid type dopant by a conventional alternate dipping method or the like can also be adopted. As a result, the conductive polymer film having a higher coverage with the conductive polymer inside the pores from the vicinity of the center of the porous metal porous body to the outer surface and having high adhesion with the dielectric layer is formed on the dielectric layer. Can be formed on the body layer, the highest capacity achievement rate in the production method of the present invention,
It is possible to obtain a high-quality capacitor with good frequency characteristics.

[0040]

EXAMPLES Examples of the present invention will be described below. Regarding the preparation of the monomer solution, a pyrrole was dissolved in an aqueous solution containing 10 vol% of isopropyl alcohol so as to be 0.05 mol / l to prepare a monomer solution I.
Further, pyrrole was dissolved in an aqueous solution containing 10 vol% of isopropyl alcohol so as to be 0.1 mol / l to prepare a monomer solution II.

For the preparation of the oxidizing agent solution, iron (III) sulfate 0.05 mol / l as an oxidizing agent and an alkylnaphthalene sulfonate ion as an organic acid dopant in N were added to an aqueous solution containing 10 vol% of isopropyl alcohol.
An oxidant solution I was prepared by dissolving the salt a in a form of 0.03 mol / l.

Further, isopropyl alcohol was added at 10 vo
In an aqueous solution containing 1%, 0.1 mol / l of iron (III) sulfate as an oxidant and 0.05 of an alkylnaphthalenesulfonate ion as an organic acid dopant in the form of Na salt are used.
It was dissolved so as to be mol / l to obtain an oxidizing agent solution II.

Further, isopropyl alcohol was added at 10 vo
0.05 mol of iron (III) sulfate in an aqueous solution containing 1%
The solution was dissolved to give an oxidant solution III.
Iron (III) sulfate was dissolved in an aqueous solution containing 10 vol% of isopropyl alcohol so as to have a concentration of 0.1 mol / l to obtain an oxidizing agent solution IV.

Next, the tantalum powder is compression-molded together with the lead and then fired to obtain 1.4 mm × 3.0 mm × 3.8.
After forming the porous body of mm, the pore surface and the outer surface of the tantalum porous body were formed in a phosphoric acid aqueous solution at a formation voltage of 30 V to form an oxide film dielectric layer, which was used as a porous body for a capacitor.

A conductive polymer layer was formed on the prepared dielectric layer of the porous body for the capacitor by the following chemical oxidation polymerization method to form a cathode, and a lead plate serving as a cathode current collector was provided outside. A carbon and silver layer was connected between the conductive polymer layer and the current collector lead plate to form an electrolytic capacitor using the tantalum lead as an anode terminal and the lead plate connected with silver as a cathode terminal. The state of coating of the dielectric layer inside the porous body with the conductive polymer was observed on the fracture surface. Moreover, the electrostatic capacitance at 120 Hz and 1 kHz as an electrolytic capacitor was measured.

Example (1) The monomer solution I and the oxidant solution I were mixed while being kept at 5 ° C., the porous metal body was immersed in this mixed solution, and the lead was heated to form the porous body through the lead. Heat to 30 ° C and hold,
A conductive polymer layer containing a dopant was formed inside the pores of the porous body and on the surface of the dielectric layer. The polymerization rate in the heated porous body was about 4 times the polymerization rate in the solution. After forming the conductive polymer, it was washed and dried.

Example (2) The monomer solution I and the oxidant solution I were mixed while being kept at 5 ° C. The porous body was immersed in this mixed solution to impregnate the porous body with the solution, and then the porous body was dissolved. 80% relative humidity
The porous body was heated and held at 30 ° C. through the lead in the atmosphere of 1 to form a conductive polymer layer containing a dopant inside the pores of the porous body and on the surface of the dielectric layer on the surface of the porous body.
After that, washing and drying were performed, and the operation of impregnation, lifting and heating and washing and drying was repeated 5 times.

Example (3) A method of forming a conductive polymer layer by accommodating a porous body in a reaction element case will be described. FIG. 2 shows the porous body 1 housed in the element case 3. The volume of the reaction element case 3 is set to the porous body 1.
The volume of the solution is doubled, and the monomer solution II and the oxidant solution II are kept at 5 ° C. in advance and mixed, and immediately the element case 3
Was injected into the gap 31 between the porous body 1 and the porous body 1. Then, the porous body was kept at 30 ° C. together with the reaction element case, and a conductive polymer layer containing a dopant was formed on the dielectric film of the porous body.
Then, it was washed and dried. Using this case, the operation consisting of solution mixture injection, heating and washing / drying was repeated 5 times.

Example (4) The monomer solution II and the oxidant solution IV were kept at 5 ° C. and mixed,
By immersing the porous body in this mixed solution, a conductive polymer film containing no organic acid dopant (including sulfate ion) was formed inside the pores of the porous body and on the surface of the dielectric layer on the surface of the porous body. Then, it was washed and dried. After that, the monomer solution I and the oxidant solution I are held and mixed at 5 ° C., the porous body subjected to the above treatment is immersed in this mixed solution, and the organic acid is heated while heating the porous body to 30 ° C. through the lead. A conductive polymer layer containing a system dopant was formed on the conductive polymer film containing no organic acid dopant. Finally, it was washed and dried again.

Example (5) The monomer solution I and the oxidant solution I were kept at 5 ° C. and mixed,
After immersing the porous body in this mixed liquid to impregnate the solution with the solution, the porous body is pulled up from the solution, and the porous body is heated to 30 ° C. through a lead in an atmosphere of 80% relative humidity to remove the dopant. A conductive polymer layer containing the same was formed inside the pores of the porous body and on the surface of the dielectric layer on the surface of the porous body, and then washed and dried. Then, the conductive polymer layer was further formed by repeating the alternating immersion of the porous body in the monomer solution II and the oxidant solution II and the dry washing 15 times.

Example (6) The monomer solution I and the oxidant solution III were kept at 5 ° C. and mixed, and the porous body was immersed in the mixed solution to impregnate the porous body with the solution. 80% relative humidity
Heating the porous body to 30 ° C through the reed in the atmosphere of
Does not contain organic acid type dopants (including sulfate ions)
The conductive polymer film was formed inside the pores of the porous body and on the surface of the dielectric layer on the surface of the porous body, and then washed and dried. After that, by alternately immersing the porous body in the monomer solution II and the oxidant solution II and repeating the washing and drying 15 times, the conductive polymer film containing the organic acid-based dopant can be formed on the conductive polymer film containing no organic acid-based dopant. A polymer layer was formed.

Example (7) As the first pretreatment, the monomer solution I and the oxidant solution III were kept at 5 ° C. and mixed, and the porous body was immersed in this mixed solution to impregnate the solution with the porous body. , The porous body is pulled up from the solution, the porous body is heated to 30 ° C. through the lead in an atmosphere of relative humidity 80%, and the conductive polymer film containing no organic acid dopant (including sulfate ion) is porous. It was formed inside the pores of the body and on the surface of the dielectric layer on the surface of the porous body, and washed and dried. After that, as a second pretreatment, the monomer solution I and the oxidant solution I are held at 5 ° C. and mixed, and the porous body is immersed in this mixed solution to impregnate the porous body with the solution. The porous body is pulled up and heated to 30 ° C. through the lead in an atmosphere of 80% relative humidity, and the conductive polymer film containing the organic acid dopant is placed on the conductive polymer film containing no organic acid dopant. And was washed and dried.
Then, as the main treatment, the monomer solution II and the oxidant solution are used.
By alternately immersing the porous body in II and washing and drying 15 times, a conductive polymer layer further containing an organic acid type dopant was formed.

As the conventional example (8), the conductive polymer layer containing the dopant was formed inside the pores of the porous body by repeating the alternating immersion of the porous body in the monomer solution II and the oxidizing agent solution II and washing and drying 15 times. It was deposited and formed on the surface of the dielectric layer on the surface of the porous body.

The porous body of the electrolytic capacitor produced as described above was broken, and the state of formation of the conductive polymer layer was observed on the broken surface. In the conventional example (8), the coverage with the conductive polymer in the central portion of the porous body is insufficient, whereas in the methods of Examples (1) to (7), which are the methods of the present invention, up to the central portion. It was found that the coverage with the conductive polymer was improved.

[0055]

[Table 1]

Table 1 shows the measurement results of the capacitance of the electrolytic capacitor. The porous body used in this example has a capacity of 10
Although it was designed and manufactured to be a 0 μF product, Table 1
As is clearer, in the conventional example (8), the capacity achieved only about 70%. However, in Examples (1), (2), and (3) according to the heating method and the liquid injection method of the present invention, a capacity of 90% or more can be achieved, and Example (4) further pretreated, In (5), (6) and (7), the capacity could be achieved almost completely. In particular, comparing the capacities at a frequency of 120 Hz and 1 kHz, Examples (4), (6), and (7) in which a conductive polymer layer containing no organic acid dopant was provided as a pretreatment were The characteristics were very good and good capacitor characteristics were shown without a decrease in capacitance at 1 kHz. In particular, a conductive polymer layer containing no organic acid dopant was formed as the first pretreatment, and a conductive polymer layer containing an organic acid dopant was preferentially formed from the inside as the second pretreatment. In Example (7), the capacity achievement and the high frequency characteristics were the most excellent.

Here, when a conductive polymer layer containing no organic acid type dopant is provided, it is confirmed by a scanning electron microscope that the formed conductive polymer layer is uniformly formed in a film shape. Confirmed by observation. The present inventors have confirmed that this homogeneous film has excellent adhesion to the dielectric layer and significantly reduces the resistance as the conductive polymer layer.
Therefore, when a conductive polymer layer containing no organic acid dopant as in Examples (4), (6) and (7) of the present invention is formed on the surface of the dielectric layer in advance, the cathode becomes Since the resistance is low, it is presumed that the capacity drawing rate at high frequencies is improved.

Although pyrrole was used as the monomer in this example, the present invention is not limited in kind as long as it is a heterocyclic five-membered ring compound or its derivative. Further, in the present example, the organic acid-based dopant was added in the form of the alkylnaphthalenesulfonic acid Na salt, but the same effect can be obtained with other aryl arylsulfonate ions, and further, when the arylyl phosphate ion is used. The conductive polymer layer having better heat resistance was formed.

In this Example (1), the temperature of the porous body or the inside of the porous body was set at 25 ° C. higher than the temperature of the solution outside the porous body.
The effect was confirmed by raising the temperature, but the effect was sufficiently confirmed by raising the temperature by 10 ° C. or more. Further, in the present Example (1), the actual polymerization formation rate of the conductive polymer layer inside the porous body was about 4 times the polymerization formation rate outside, but it is effective to control the polymerization formation rate to 2 times or more. Was confirmed.

In this Example (2), the effect was confirmed by setting the atmosphere for pulling up the porous body as an atmosphere containing 80% of the solvent saturated vapor pressure of solvent vapor (relative vapor pressure 80%). The effect was sufficiently recognized in an atmosphere having a vapor pressure of 70% or more. Further, the polymer deposition weight per hour in the dipping solution in this Example (2) was about 5% of the blended monomer weight, but 10
It was confirmed that the conductive polymer layer was formed quite efficiently by controlling the content to be not more than%.

In the present Example (3), the size of the internal volume of the reaction element case was twice the size of the porous body,
It was confirmed that the reaction yield was good when the amount was 4 times or less. In addition, the amount of polymer deposition after mixing the monomer solution and the oxidizing agent solution in Example (3) until injection into the element case for reaction was 2% or less with respect to the charged monomer weight, but 10% or less. It was confirmed that the effect was sufficiently achieved by controlling the reaction.

In the present embodiment (4), the formation of the conductive polymer film containing no organic acid dopant, which is formed as a pretreatment, is performed by immersing the porous body in a solution obtained by mixing the oxidant solution and the monomer solution. However, the same effect can be obtained by repeating the immersion cleaning and drying, or by forming the porous body by alternating immersion cleaning and drying once or repeatedly in the oxidizing agent solution and the monomer solution. . In this case, it is not limited which of the oxidant solution and the monomer solution is dipped first. Further, the same effect was obtained even when the conductive polymer film containing no organic acid type dopant was formed by any of the heating methods of the present invention. Further, the same effect was obtained in this treatment by using either the heating method or the liquid injection method of the present invention.

Further, in Examples (5), (6) and (7), the conductive polymer layer formed as the main treatment after the pretreatment by the heating method of the present invention was formed by using an oxidizing agent solution and It was performed by repeatedly performing alternate immersion cleaning and drying of the porous body in the monomer solution, but in this case, which of the oxidant solution and the monomer solution is immersed first is not limited. Further, the same effect was obtained by forming the porous body by immersing it in a solution obtained by mixing the oxidant solution and the monomer solution. Further, the same effect was obtained by using any of the heating methods of the present invention as the pretreatment. Further, although the tantalum electrolytic capacitor is shown in this embodiment, the type of valve metal is not limited.

[0064]

As described above, according to the present invention, a solution which is immersed in forming a conductive polymer layer by a chemical oxidative polymerization method in a porous body of anodic metal which has been subjected to a chemical conversion treatment to form a dielectric layer. By heating the porous body of the anode in or after pulling up, the polymerization formation of the conductive polymer layer on the surface of the dielectric layer of the pores inside the porous body is preferentially promoted, and the internal space is reached to the center of the porous body. The coverage of the hole surface with the conductive polymer can be improved.

Further, according to the present invention, by mixing the monomer solution and the oxidant solution at the same time as or immediately before the injection into the porous body, the coverage with the conductive polymer can be improved to the deep pores of the porous body. it can. At this time, by providing an element case for reaction and limiting the reaction space, the conductive polymer can be formed in the porous body in good yield.

As described above, it is possible to secure a large effective electrode area as a capacitor with high yield and efficiency, improve the capacity achievement rate, and improve the component yield.

Further, according to the present invention, a conductive polymer layer containing no organic acid type dopant is previously formed as a dense film on the surface of the dielectric layer, and a conductive film containing an organic acid type dopant is formed thereon. Since the polymer layer is formed, the resistance of the conductive polymer layer can be further reduced, the capacity achievement rate is high, and the electrolytic capacitor having low resistance and excellent high frequency characteristics can be provided.

Further, by adopting the conductive polymer layer heating forming method of the present invention as the pretreatment, it is possible to obtain very excellent characteristics even if the subsequent treatment is carried out by the conventional forming method. Also, a good capacitor can be provided very simply.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a porous body used in an embodiment of the present invention.

FIG. 2 is a perspective view showing a storage state of a porous capacitor body in a reaction element case according to an embodiment of the present invention.

[Explanation of symbols]

1 Porous body 2 leads 3 Element case for reaction

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-45481 (JP, A) JP-A-7-122464 (JP, A) JP-A-3-200313 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01G 9/028 H01G 9/00

Claims (33)

(57) [Claims] 1. A method for producing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is an oxide layer of the valve metal, and the cathode is a conductive polymer layer containing a dopant. The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, and the method for forming the conductive polymer layer includes a monomer and an oxidant. The valve metal porous body on which the dielectric layer is formed is dipped in a solution containing a dopant, and then the porous body or the inside of the porous body is heated at the temperature outside the porous body while the porous body is immersed in the solution. By keeping the temperature higher than the solution temperature, the polymerization reaction inside the porous body is made faster than the polymerization reaction in the solution to form a conductive polymer inside the porous body, and the polymerization reaction rate inside the porous body
Is at least twice as fast as the polymerization reaction rate in the solution . 2. A method for producing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is an oxide layer of the valve metal, and the cathode is a conductive polymer layer containing a dopant. The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, and the method for forming the conductive polymer layer includes a monomer and an oxidant. The valve metal porous body on which the dielectric layer is formed is dipped in a solution containing a dopant, and then the porous body or the inside of the porous body is heated at the temperature outside the porous body while the porous body is immersed in the solution. The temperature is kept higher than the solution temperature, the polymerization reaction inside the porous body is made faster than the polymerization reaction in the solution to form a conductive polymer inside the porous body , and the porous body or the heating method of the inside of the porous body is
A method for manufacturing an electrolytic capacitor, characterized in that a lead portion connected to the portion is heated as a heat conducting medium . Wherein the porous body or method of manufacturing an electrolytic capacitor according to claim 1 or 2, characterized in that the temperature of the porous body portion higher 10 ° C. or higher than the porous body outside of the solution temperature. 4. A method of manufacturing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is an oxide layer of the valve metal, and the cathode is a conductive polymer layer containing a dopant, The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, and the method for forming the conductive polymer layer includes a monomer, an oxidant and a dopant. In a solution containing, the valve metal porous body on which the dielectric layer has been formed is immersed to impregnate the solution inside the porous body, and then the porous body is pulled up from the solution and kept at a temperature higher than the solution temperature to carry out a polymerization reaction. to promote, the porous interior to form a conductive polymer layer, the polymer precipitated heavy per hour in a solution the dipping
The method for producing an electrolytic capacitor is characterized in that the amount is 10% or less based on the weight of the blended monomer . 5. The anode is a valve metal porous body, and the dielectric layer is
An oxide layer of the valve metal, the cathode containing a dopant.
It is a method of manufacturing an electrolytic capacitor that is a conductive polymer layer.
The conductive polymer layer is an oxide capable of polymerizing the monomer.
Polymer polymerized in a solution containing an agent and a dopant
A layer, the method of forming the conductive polymer layer, a monomer and an oxidizing agent
Forming the dielectric layer in a solution containing a dopant
The valve metal porous body was immersed and the inside of the porous body was impregnated with the solution.
After that, the porous body is pulled up from the solution and the temperature is higher than the solution temperature.
Hold the temperature to accelerate the polymerization reaction,
A conductive metal layer is formed, and the valve metal porous body impregnated with the solution is heated from the solution temperature.
The atmosphere when holding at a high temperature is the temperature of the solution.
In an atmosphere containing 70% or more of the saturated vapor pressure of solvent vapor
A method of manufacturing an electrolytic capacitor, which is characterized by the following . 6. The anode is a valve metal porous body, and the dielectric layer is
An oxide layer of the valve metal, the cathode containing a dopant.
It is a method of manufacturing an electrolytic capacitor that is a conductive polymer layer.
The conductive polymer layer is an oxide capable of polymerizing the monomer.
Polymer polymerized in a solution containing an agent and a dopant
A layer, the method of forming the conductive polymer layer, a monomer and an oxidizing agent
Forming the dielectric layer in a solution containing a dopant
The valve metal porous body was immersed and the inside of the porous body was impregnated with the solution .
After that, the porous body is pulled up from the solution and the temperature is higher than the solution temperature.
Hold the temperature to accelerate the polymerization reaction,
Form a conductive polymer layer, pull up the porous body from the solution, from the solution temperature
The heating method for maintaining a high temperature is connected inside the porous body.
The porous body is heated by using the lead part as a heat conducting medium.
And a method of manufacturing an electrolytic capacitor. 7. The operation according to claim 4 , wherein the operation of impregnating the porous body with the solution and the operation of polymerizing the monomer at a temperature higher than that of the solution after being pulled up are repeated a plurality of times. Manufacturing method of electrolytic capacitor. 8. A method for producing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is an oxide layer of the valve metal, and the cathode is a conductive polymer layer containing a dopant. The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, and the method for forming the conductive polymer layer comprises forming the dielectric layer. After storing the formed valve metal porous body in advance in the element case for reaction, a monomer solution containing a dopant in at least one of them and an oxidant solution are injected into the element case at the same time or after mixing, thereby forming a porous body. A method for producing an electrolytic capacitor, which comprises forming a conductive polymer layer inside and outside. 9. The polymer deposition weight before mixing and injecting the monomer solution and the oxidant solution into the element case is 10% or less of the charged monomer amount.
8. The method for manufacturing an electrolytic capacitor as described in 8 . 10. A conductive polymer layer is formed by injecting the monomer solution and the oxidant solution into the element case, and then making the temperature of the porous body higher than the solution temperature before the injection to accelerate the polymerization reaction. 10. The method for manufacturing an electrolytic capacitor according to claim 8 or 9 . 11. The method of manufacturing an electrolytic capacitor according to claim 8, 9 or 10 , wherein the method for heating the porous body heats a lead portion connected to the inside of the porous body as a heat conduction medium. 12. The method for producing an electrolytic capacitor according to claim 8, wherein the operation of forming the conductive polymer layer containing the dopant by the polymerization reaction is repeated a plurality of times. 13. The method for manufacturing an electrolytic capacitor according to claim 8, wherein the inner volume of the element case is more than 1 time and not more than 4 times the size of the valve metal porous body element. 14. At least one of the dopants is an organic acid type, and prior to forming the conductive polymer layer containing the dopant, as a pretreatment, a conductive polymer layer containing no organic acid type dopant is prepared. claims 1, characterized in that pre-formed within the porous body 1
3. The method for manufacturing an electrolytic capacitor as described in any one of 3 above. 15. The valve metal porous body on which the dielectric layer is formed is immersed in a solution containing a monomer and an oxidizing agent and containing no organic acid dopant, and the pretreatment is performed by a polymerization reaction inside the porous body. The method of manufacturing an electrolytic capacitor according to claim 14 , wherein the conductive polymer layer containing no organic acid dopant is formed. 16. In the pretreatment, the valve metal porous body having the dielectric layer formed thereon is alternately immersed in a monomer solution containing no organic acid dopant and an oxidant solution to carry out a polymerization reaction inside the porous body. 15. The method for producing an electrolytic capacitor according to claim 14 , wherein the conductive polymer layer containing no organic acid type dopant is formed by. 17. The pretreatment comprises immersing the valve metal porous body having the dielectric layer formed in a solution containing a monomer and an oxidant and not containing an organic acid dopant, and then immersing the porous body or the porous body. By making the temperature inside the body higher than the solution temperature outside the porous body, the polymerization reaction inside the porous body is made faster than the outside polymerization reaction, and the conductive polymer does not contain the organic acid dopant inside the porous body. The method for manufacturing an electrolytic capacitor according to claim 14 , wherein a layer is formed. 18. The valve metal porous body having a dielectric layer formed thereon is dipped in a solution containing a monomer and an oxidant and not containing an organic acid dopant to impregnate the porous body with the solution. After that, by pulling up the porous body from the solution and maintaining the temperature higher than the solution temperature to accelerate the polymerization reaction, it is possible to form a conductive polymer layer containing no organic acid dopant inside the porous body. Claims to be characterized
15. The method for manufacturing an electrolytic capacitor as described in 14 . 19. The method for heating the porous body or the inside of the porous body in the pretreatment comprises heating a lead portion connected to the inside of the porous body as a heat conducting medium.
17. A method for manufacturing an electrolytic capacitor as described in 17 or 18 . 20. The pretreatment is characterized in that an operation of forming a conductive polymer layer containing no organic acid type dopant by the polymerization reaction is repeated a plurality of times.
20. A method for manufacturing an electrolytic capacitor according to any one of 14 to 19 . 21. A method for producing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is a valve metal oxide, and the cathode is a conductive polymer layer containing a dopant, wherein The polymer layer is a conductive polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, and the method for forming the conductive polymer layer is as a pretreatment,
The valve metal porous body on which the dielectric layer is formed is immersed in a solution containing a monomer, an oxidant and a dopant, and then the porous
By keeping the temperature of the porous body or the inside of the porous body higher than the solution temperature outside the porous body while the body is immersed in the solution, the polymerization reaction inside the porous body is made faster than the polymerization reaction outside the porous body. After forming a conductive polymer layer containing a dopant, a conductive polymer layer containing a dopant is further formed by the main treatment, and the main treatment contains a monomer, an oxidant and a dopant.
Alternate immersion of the pre-treated valve metal porous body in the solution
On the conductive polymer layer formed by the pretreatment
A conductive polymer layer containing a dopant by a polymerization reaction
A method of manufacturing an electrolytic capacitor, which comprises forming 22. A method of manufacturing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is a valve metal oxide layer, and the cathode is a conductive polymer layer containing a dopant, The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, wherein at least one of the dopants is an organic acid system, and the conductive polymer layer As a pretreatment, the valve metal porous body on which the dielectric layer is formed is immersed in a solution containing a monomer and an oxidizing agent and containing no organic acid dopant, and then the porous body or the porous body is formed. By making the internal temperature higher than the solution temperature outside the porous body, the polymerization reaction inside the porous body is made faster than the external polymerization reaction to form a conductive polymer layer containing no organic acid type dopant inside the porous body. After the formation, a conductive polymer layer containing an organic acid type dopant is formed on the conductive polymer layer containing no organic acid type dopant by this treatment. 23. A method of manufacturing an electrolytic capacitor, wherein the anode is a valve metal porous body, the dielectric layer is a valve metal oxide layer, and the cathode is a conductive polymer layer containing a dopant, The conductive polymer layer is a polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, wherein at least one of the dopants is an organic acid system, and the conductive polymer layer As the pretreatment 1, the valve metal porous body on which the dielectric layer is formed is immersed in a solution containing a monomer and an oxidizing agent and containing no organic acid dopant, and then the porous body or the porous body is formed. By making the temperature inside the body higher than the solution temperature outside the porous body, the polymerization reaction inside the porous body is made faster than the outside polymerization reaction, and the conductive polymer layer does not contain an organic acid type dopant inside the porous body. After the formation, as the pretreatment 2, the valve metal porous body after the pretreatment 1 is immersed in a solution containing a monomer, an oxidizing agent, and an organic acid dopant, and then the temperature of the porous body or the inside of the porous body is adjusted. By making the temperature of the solution outside the porous body higher than that of the solution outside the porous body, the polymerization reaction inside the porous body is made faster than that outside, and the organic acid is formed on the conductive polymer layer containing no organic acid dopant formed in Pretreatment 1. A method for producing an electrolytic capacitor, comprising forming a conductive polymer layer containing an acid-based dopant and then further forming a conductive polymer layer containing an organic acid-based dopant by this treatment. 24. A method for producing an electrolytic capacitor, wherein the anode is a valve metal, the dielectric layer is a valve metal oxide layer, and the cathode is a conductive polymer layer containing a dopant. The molecular layer is a conductive polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, wherein at least one of the dopants is an organic acid system, and the conductive polymer layer After forming the pretreatment, the valve metal porous body on which the dielectric layer has been formed is immersed in a solution containing a monomer and an oxidizing agent and not containing an organic acid dopant, and the porous body is impregnated with the solution. , By pulling up the porous body from the solution, by maintaining a temperature higher than the solution temperature to accelerate the polymerization reaction, after forming a conductive polymer layer containing no organic acid-based dopant inside the porous body, the main treatment A method for producing an electrolytic capacitor, comprising forming a conductive polymer layer containing a more organic acid type dopant on a conductive polymer layer not containing the organic acid type dopant. 25. A method for producing an electrolytic capacitor, wherein the anode is a valve metal, the dielectric layer is a valve metal oxide layer, and the cathode is a conductive polymer layer containing a dopant. The molecular layer is a conductive polymer layer obtained by polymerizing the monomer in a solution containing a polymerizable oxidant and a dopant, wherein at least one of the dopants is an organic acid system, and the conductive polymer layer As a pretreatment 1, as a pretreatment 1, the valve metal porous body having the dielectric layer formed thereon was dipped in a solution containing a monomer and an oxidant but not containing an organic acid dopant to impregnate the inside of the porous body with the solution. After that, by pulling up the porous body from the solution, by maintaining a temperature higher than the solution temperature to accelerate the polymerization reaction, after forming a conductive polymer layer containing no organic acid-based dopant inside the porous body, pretreatment As 2, the valve metal porous body after the pretreatment 1 is immersed in a solution containing a monomer, an oxidizing agent, and an organic acid-based dopant to impregnate the inside of the porous body with the solution, and then the porous body is pulled up from the solution. A conductive polymer layer containing an organic acid type dopant is formed on the conductive polymer layer containing no organic acid type dopant formed in Pretreatment 1 by maintaining the temperature higher than the solution temperature to accelerate the polymerization reaction. The method for producing an electrolytic capacitor, which further comprises forming a conductive polymer layer containing an organic acid-based dopant by this treatment after forming. 26. The method for producing an electrolytic capacitor according to claim 21 , wherein the pretreatment comprises repeating an operation of forming a conductive polymer layer by the polymerization reaction a plurality of times. 27. The method of holding at a temperature higher than the solution temperature of the porous material in the pretreatment, any to claims 21, characterized in that heating the lead portions as a heat transfer medium 26 connecting the interior porous body A method for manufacturing an electrolytic capacitor as described in 1. 28. The main treatment is formed by the pretreatment, wherein the pretreated valve metal porous body is alternately immersed in a monomer solution containing at least one of the dopants and an oxidant solution. 27. The method for producing an electrolytic capacitor according to claim 21 , wherein a conductive polymer layer containing a dopant is formed on the conductive polymer layer by a polymerization reaction. 29. The method for producing an electrolytic capacitor according to claim 21 , wherein in the main treatment, an operation of forming a conductive polymer layer containing the dopant by the polymerization reaction is repeated a plurality of times. 30. A method of manufacturing an electrolytic capacitor according to 29 any one to the monomer claims 1 to heterocyclic five-membered ring compound or its derivative. 31. The dopant or the organic acid-type dopant, method of manufacturing an electrolytic capacitor according to any one of claims 1 to 29, which is earth drill sulfonate ion or Arirurin ion. 32. The valve metal is method of manufacturing an electrolytic capacitor according to any one of claims 1 to 29 is aluminum or tantalum. 33. The electrolytic capacitor produced using the method for forming a conductive polymer layer according to any one of claims 1 to 32.