TWI606475B - Solid electrolytic capacitor and method for producing the same - Google Patents

Description

Solid electrolytic capacitor and method of manufacturing same

The present invention relates to a solid electrolytic capacitor and a method of manufacturing the same.

In recent years, a solid electrolytic capacitor has been developed which is formed of a dielectric oxide film formed on the surface of an anode body (film-forming metal) containing a porous metal body such as aluminum, tantalum, niobium, titanium or magnesium. In the above, a solid electrolyte layer in which a conductive polymer is used as a solid electrolyte and a cathode body are sequentially formed.

Compared with the conventional solid electrolytic capacitor using manganese dioxide as a solid electrolyte, the solid electrolytic capacitor has a conductivity 10 times to 100 times higher, and the Equivalent Series Resistance (ESR) can be greatly reduced. The industry expects to apply it to various applications such as absorption of high-frequency noise in small electronic devices.

As a method of forming a solid electrolyte layer on a dielectric oxide film, it is generally a chemical oxidation polymerization method or an electrolytic polymerization method.

The chemical oxidative polymerization method is a method in which a film forming metal having a dielectric oxide film formed on a surface thereof is immersed in a monomer containing a conductive polymer such as Ethylenedioxythiophene (EDOT), pyrrole or aniline. The solid electrolyte layer is formed by directly reacting a monomer with an oxidizing agent in a solution of an oxidizing agent or a dopant (conductive auxiliary) and on a dielectric oxide film.

On the other hand, the electrolytic polymerization method is a method in which a conductive underlayer is formed on a dielectric oxide film in advance to form a monomer containing a conductive polymer. An electrolyte solution of the dopant is applied onto the underlayer to form a coating film, and then a voltage is applied between the coating film and the underlayer to form a solid electrolyte layer.

For example, Patent Document 1 discloses a method of forming a solid electrolyte layer by a chemical oxidative polymerization method. Specifically, a surface of an aluminum electrode subjected to surface oxidation is applied to dissolve a solution of EDOT and iron (III) p-toluenesulfonate which also serves as an oxidizing agent and a dopant in an organic solvent to form a polymer coating film, and then remove the organic solvent. To form a solid electrolyte layer.

Further, Patent Document 2 discloses a method in which a solid electrolyte layer of polypyrrole or polyaniline formed by a chemical oxidative polymerization method is used as a primer layer, and a homogeneous solid electrolyte is formed on the surface of the underlayer by electrolytic polymerization. Floor.

However, since these chemical oxidative polymerization methods or electrolytic polymerization methods carry out polymerization reaction on the dielectric oxide film, impurities are likely to be mixed into the solid electrolyte layer, which may cause short-circuiting. In addition, the manufacturing steps are apt to become complicated.

Therefore, as a method of forming a solid electrolyte layer by chemical oxidative polymerization or electrolytic polymerization on a dielectric oxide film, a slurry polymer coating method has been proposed. The slurry polymer coating method is a method in which a monomer is polymerized in advance to prepare a polymer (conductive polymer), and then a dispersion containing the polymer is applied onto a dielectric oxide film and dried. A coating film is formed to thereby form a solid electrolyte layer.

The slurry polymer coating method does not perform polymerization on a dielectric oxide film as in a chemical oxidative polymerization method or an electrolytic polymerization method, and uses a conductive material that chemically oxidizes a monomer and an oxidizing agent and a dopant in advance and has completed polymerization. Polymer. Therefore, it is not necessary to carry out a polymerization reaction on the dielectric oxide film, so The mixing into the solid electrolyte layer is less, and the control of the manufacturing steps is relatively easy.

However, in the case of the slurry polymer coating method, it is difficult for the dispersion of the conductive polymer to be impregnated into the interior of the dielectric oxide film. As a result, it is difficult to form the solid electrolyte layer in the inside (fine pores) of the fine concavities and convexities of the dielectric oxide film, and the solid electrolyte layer is formed only in the surface layer. Therefore, there is a problem that the capacitance expression rate of the obtained solid electrolytic capacitor is lowered.

Therefore, a method of forming a solid electrolyte layer using a conductive polymer soluble in water or an organic solvent has been proposed.

For example, Patent Document 3 discloses a method in which a polymer solution obtained by dissolving a specific soluble aniline-based conductive polymer in water or an aqueous organic solvent is applied onto a dielectric oxide film formed on a metal surface of a film. And dried to form a solid electrolyte layer.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3040113

[Patent Document 2] Japanese Patent Special Fair No. 3-61331

[Patent Document 3] Japanese Patent Laid-Open Publication No. Hei 9-22833

However, in recent years, solid electrolytic capacitors have been reduced in size, weight, and capacity. Therefore, the porous film-forming metal is made finer or has fine pores of various forms. Therefore, the inside of the dielectric oxide film formed on the surface of the film-forming metal is also finer and more complicated, and when the conductive polymer is to be impregnated into the interior of the dielectric oxide film, as in Patent Document 3 It is not sufficient to use only a polymer solution as in the method described in the above.

In addition, the structure of the solid electrolytic capacitor is roughly classified into a laminated type and a wound type, and particularly in the case of a wound type solid electrolytic capacitor, the polymer solution is sufficiently impregnated between the dielectric oxide film and the cathode. It is not easy in spacers such as fibers or paper. In particular, when the insulating oil is infiltrated into the spacer, the polymer solution is difficult to be impregnated.

The present invention has been made in view of the above circumstances, and provides a solid electrolytic capacitor in which a conductive polymer is sufficiently impregnated into an anode body (film forming metal) having a dielectric oxide film, and a conductive material can be easily produced. A method of sufficiently impregnating a solid electrolytic capacitor into the inside of an anode body (film forming metal) having a dielectric oxide film.

As a result of intensive studies by the inventors of the present invention, it has been found that the impregnation property of the conductive polymer to the inside of the fine concavities and convexities of the dielectric oxide film is remarkably improved by specifying the average particle diameter of the conductive polymer or the like, thereby completing the present invention. .

In other words, the solid electrolytic capacitor of the present invention is characterized in that it has a solid electrolyte layer which contains a conductive polymer satisfying the following condition (A) and which satisfies the following condition (B). The polymer solution is applied onto a dielectric oxide film formed on the surface of the metal formed by the film, and dried.

Condition (A): Among the one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive polymer solution containing 1% by mass of a conductive polymer, the particles are included. The volume average particle diameter of the smallest particle distribution in which the diameter becomes the smallest peak is less than 26 nm.

Condition (B): forming a solid electrolyte in which a conductive polymer solution containing a conductive polymer is applied onto a dielectric oxide film formed on the surface of aluminum having a capacitance of 95 μF/cm ² and dried. When a laminated aluminum solid electrolytic capacitor is produced in a layer, the capacitance generating ratio of the laminated aluminum solid electrolytic capacitor is 70% or more.

Here, the content of the conductive polymer in the conductive polymer solution is preferably 9% by mass or less.

Further, it is preferable that the surface tension of the conductive polymer solution is less than 67 mN/m.

Further, it is preferable that the conductive polymer solution contains a surfactant.

Further, it is preferable that the conductive polymer has a repeating unit represented by the following general formula (1).

In the formula (1), R ¹ to R ⁴ are each independently -H, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. Or a salt thereof, a hydroxyl group, a nitro group, -F, -Cl, -Br or -I, and at least one of R ¹ to R ⁴ is an acidic group or a salt thereof. Here, the acidic group means a sulfonic acid group or a carboxyl group.

Further, the method for producing a solid electrolytic capacitor according to the present invention includes the step of applying a conductive polymer solution containing a conductive polymer satisfying the following condition (A) and satisfying the following condition (B); The film is formed on the dielectric oxide film formed on the surface of the metal; and the applied conductive polymer solution is dried to form a solid electrolyte layer.

Condition (A): Among the one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive polymer solution containing 1% by mass of a conductive polymer, the peak having the smallest particle diameter The volume average particle diameter of the smallest particle distribution is less than 26 nm.

Condition (B): forming a solid electrolyte in which a conductive polymer solution containing a conductive polymer is applied onto a dielectric oxide film formed on the surface of aluminum having a capacitance of 95 μF/cm ² and dried. When a layered aluminum solid electrolytic capacitor is produced in a layer, the capacitance performance of the laminated aluminum solid electrolytic capacitor is 70% or more.

Here, the content of the conductive polymer in the conductive polymer solution is preferably 9% by mass or less.

Further, it is preferable that the surface tension of the conductive polymer solution is less than 67 mN/m.

Further, the method for producing a solid electrolytic capacitor of the present invention is characterized by comprising the steps of: applying an organic solvent or a mixed solvent of an organic solvent and water to a dielectric oxide film formed on a surface of a film-forming metal; Dielectric oxidation of cloth organic solvent or mixed solvent of organic solvent and water A conductive polymer solution containing a conductive polymer is applied onto the film; and the applied conductive polymer solution is dried to form a solid electrolyte layer.

Here, it is preferable that the conductive polymer satisfies the following condition (A), and the conductive polymer solution satisfies the following condition (B).

Condition (A): Among the one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive polymer solution containing 1% by mass of a conductive polymer, the peak having the smallest particle diameter The volume average particle diameter of the smallest particle distribution is less than 26 nm.

Condition (B): A solid formed by applying a conductive polymer solution containing a conductive polymer to a dielectric oxide film formed on the surface of aluminum having a capacitance of 95 μF/cm ² and drying the same When the electrolyte layer is used to produce a laminated aluminum solid electrolytic capacitor, the capacitance performance of the laminated aluminum solid electrolytic capacitor is 70% or more.

Moreover, it is preferable that the content of the conductive polymer in the conductive polymer solution is 9% by mass or less.

Further, it is preferable that the surface tension of the conductive polymer solution is less than 67 mN/m.

In the solid electrolytic capacitor of the present invention, the conductive polymer is sufficiently impregnated into the inside of the anode body (film forming metal) having the dielectric oxide film.

Further, according to the method for producing a solid electrolytic capacitor of the present invention, the conductive polymer can be easily and sufficiently impregnated to have a dielectric oxide film. A solid electrolytic capacitor up to the inside of the anode body (the film is formed of a metal).

Hereinafter, the present invention will be described in detail.

In the present invention, the "conductive polymer" means a conductive polymer or a conductive polymer and a dopant thereof, and the "conductive polymer solution" means a conductive polymer or A solution in which a conductive polymer and a dopant thereof are dissolved or dispersed.

In the present invention, the term "impregnation" means that the conductive polymer is impregnated (permeated) into the interior of the fine concavities and convexities of the dielectric oxide film, or how much is impregnated (permeated) into the dielectric oxide film. The inside of the fine unevenness.

The impregnation property can be relatively evaluated, for example, by observing the cross section of the capacitor by a scanning electron microscope or the like.

<Solid electrolytic capacitor>

An embodiment of the solid electrolytic capacitor of the present invention will be described.

Fig. 1 schematically shows the configuration of a capacitor of this embodiment. The solid electrolytic capacitor 10 of this example is a laminated solid electrolytic capacitor including a film forming metal 11, a dielectric oxide film 12 formed on the film forming metal 11, and a solid electrolyte layer formed on the dielectric oxide film 12. 13. A graphite layer 14 formed on the solid electrolyte layer 13, and a metal layer 15 formed on the graphite layer 14.

(film forming metal)

The film forming metal 11 is a porous metal body having a valve function, and Conductive. As such a film forming metal 11, a normal electrode (valve-acting metal body) used in a solid electrolytic capacitor can be used, and specifically, an electrode containing a metal material such as aluminum, tantalum, niobium or nickel can be used. As a form, a metal foil, a metal sintered body, etc. are mentioned.

Further, in the present invention, the term "electrical conductivity" means having 10 ⁹ Ω. Volume resistivity below cm.

(dielectric oxide film)

The dielectric oxide film 12 is a film formed by anodizing the film forming metal 11.

As shown in FIG. 1, the dielectric oxide film 12 formed by anodizing the film forming metal 11 reflects the surface state of the film forming metal 11, and the surface has a fine uneven shape. The period of the unevenness depends on the type of the film forming metal 11 and the like, but is usually about 200 nm or less, and the depth of the concave portion (fine pores) in which the unevenness is formed is particularly likely to depend on the type of the film forming metal 11 and the like. For example, in the case of using aluminum, the depth of the concave portion is about several tens of nm to 1 μm.

(solid electrolyte layer)

The solid electrolyte layer 13 is obtained by applying a conductive polymer solution containing a conductive polymer satisfying the following condition (A) and satisfying the following condition (B), and drying the conductive polymer solution.

Condition (A): Among the one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive polymer solution containing 1% by mass of a conductive polymer, the peak having the smallest particle diameter The volume average particle diameter of the smallest particle distribution is less than 26 nm.

Condition (B): forming a solid electrolyte in which a conductive polymer solution containing a conductive polymer is applied onto a dielectric oxide film formed on the surface of aluminum having a capacitance of 95 μF/cm ² and dried. When a layered aluminum solid electrolytic capacitor is produced in a layer, the capacitance performance of the laminated aluminum solid electrolytic capacitor is 70% or more.

The conductive polymer used in the present invention has a volume average particle diameter of less than 26 nm. When the volume average particle diameter is less than 26 nm, the conductive polymer is sufficiently impregnated into the inside of the fine concavities and convexities of the dielectric oxide film 12, so that a solid electrolytic capacitor having a high capacitance expression rate can be obtained. The volume average particle diameter of the conductive polymer is preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less from the viewpoint of more excellent impregnation properties.

The volume average particle diameter of the conductive polymer is a value measured as follows.

First, a conductive polymer solution having a concentration of a conductive polymer of 1% by mass was prepared, and the particle distribution was measured by a dynamic light scattering method using a dynamic light scattering type particle size measuring device, and corrected by the viscosity of pure water. Then, the volume average particle diameter of the smallest particle distribution including the peak having the smallest particle diameter among the obtained one or more peaks is obtained, and this is taken as the volume average particle diameter of the conductive polymer.

In the present invention, the "minimum particle distribution" refers to one or more particle distributions obtained by measuring the particle distribution by dynamic light scattering, correcting the viscosity of pure water, and analyzing the particles. Among the groups, the smallest particle size distribution. Specifically, FIG. 3, it means comprising one or more peaks of the obtained particle distribution measurement P _1, P _2, P _3, ... among the smallest diameter of the particle distribution peak P ₁ (FIG. 3, the area of the symbol S). When the peak obtained by measuring the particle distribution by the dynamic light scattering method is one, the particle distribution becomes the minimum particle distribution. Further, when a plurality of particle distributions are superimposed, waveform separation may be performed by a general analysis method such as a Gauss function or a Lorentz function incorporated in a general-purpose software or the like.

Further, the solid electrolyte layer 13 of the solid electrolytic capacitor 10 of the present invention is formed of a conductive polymer solution in which a conductive polymer solution containing a conductive polymer is applied to a capacitance per unit area of 95 μF/ When a laminated solid aluminum electrolyte electrolytic capacitor is formed on a dielectric oxide film formed on the surface of aluminum of cm ² and dried to form a laminated aluminum solid electrolytic capacitor, the capacitance performance of the laminated aluminum solid electrolytic capacitor reaches 70 %the above. When the solid electrolyte layer 13 is formed of a conductive polymer solution having a capacitance of at least 70%, the conductive polymer is sufficiently formed inside the fine concavities and convexities of the dielectric oxide film 12. Impregnation, so a solid electrolytic capacitor with high capacitance performance can be obtained.

The capacitance performance rate is obtained as follows.

First, an anodized film was formed on the surface of aluminum having a capacitance of 95 μF/cm ² per unit area, and then immersed in an aqueous solution of ammonium adipate having a concentration of 3% by mass, and the capacitance in the solution was measured. And the capacitance is taken as the maximum capacitance (Cw).

In addition, a laminated aluminum solid electrolytic capacitor was produced and the capacitance (Cs) thereof was measured, and the capacitance expression rate of the laminated aluminum solid electrolytic capacitor was determined according to the following formula (i).

Capacitance performance rate (%) = (Cs / Cw) × 100... (i)

The capacitance expression rate of the laminated aluminum solid electrolytic capacitor can be adjusted by the content of the conductive polymer in the conductive polymer solution or the like. Specifically, when the content of the conductive polymer in the conductive polymer solution is reduced, the capacitance expression ratio of the laminated aluminum solid electrolytic capacitor tends to be high.

The conductive polymer is preferably soluble in water or an organic solvent. When the conductive polymer is soluble, the conductive polymer solution is dissolved in water or an organic solvent to form a conductive polymer solution, and then the conductive polymer solution is applied onto the dielectric oxide film 12. By the simple method of drying, the solid electrolyte layer 13 in which the conductive polymer is sufficiently impregnated into the fine concavities and convexities of the dielectric oxide film 12 can be formed.

The soluble conductive polymer is not particularly limited as long as it is dissolved in water or an organic solvent. From the viewpoint of solubility, a sulfonic acid group (-SO ₃ H) and/or a sulfonic acid group can be preferably used. Or a conductive polymer of a carboxyl group (-COOH). Further, the sulfonic acid group and the carboxyl group may be contained in the soluble conductive polymer in an acid state (-SO ₃ H or -COOH), and may be contained in an ion state (-SO ₃ ^- , -COO ^- ). In soluble conductive polymers.

In the present invention, "soluble" means that 0.1 g or more is uniformly dissolved in 10 g of water or an organic solvent (liquid temperature: 25 ° C).

As such a conductive polymer, a compound having a repeating unit represented by the following formula (1) is preferred.

In the formula (1), R ¹ to R ⁴ are each independently -H, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. Or a salt thereof, a hydroxyl group, a nitro group, -F, -Cl, -Br or -I, and at least one of R ¹ to R ⁴ is an acidic group or a salt thereof.

Here, the "acid group" means a sulfonic acid group or a carboxyl group. That is, in the formula (1), at least one of R ¹ to R ⁴ is -SO ₃ H, -SO ₃ ^- , -COOH or -COO ^- . In particular, from the viewpoint of ease of production, it is preferred that any one of R ¹ to R ⁴ is a linear or branched alkoxy group having a carbon number of 1 to 4, and any other one is -SO ₃ ^- or - SO ₃ H, the remainder is H.

In addition, the "acid group salt" means at least one of an alkali metal salt, an ammonium salt, and a substituted ammonium salt of an acidic group.

The conductive polymer preferably contains all repeating units (100 mol%) constituting the conductive polymer, and the repeating unit represented by the above formula (1) is 20 mol% to 100 mol%. More preferably, it is 50% by mole to 100% by mole, and it is particularly preferably 100% by mole from the viewpoint of excellent pH in water and an organic solvent.

In addition, it is preferable that the conductive polymer contains 10 or more repeating units represented by the above formula (1) in one molecule.

As a compound having a repeating unit represented by the above formula (1), a poly(2-sulfonic acid-5-methoxy-1,4-imino group) is particularly preferable from the viewpoint of excellent solubility. benzene).

The mass average molecular weight of the conductive polymer is preferably from 3,000 to 1,000,000, more preferably from 3,000 to 300,000, and particularly preferably from 3,000 to 100,000. When the mass average molecular weight of the conductive polymer is 3,000 or more, conductivity, film formability, and film strength are excellent. When the mass average molecular weight of the conductive polymer is 1,000,000 or less, the solubility in water and an organic solvent is excellent.

Further, the mass average molecular weight of the conductive polymer is a value obtained by measuring the molecular weight by gel permeation chromatography (GPC) and converting it into sodium polystyrene sulfonate.

The conductive polymer can be obtained by various synthesis methods such as chemical polymerization or electrolytic polymerization. Further, it can be produced by a synthesis method described in, for example, Japanese Laid-Open Patent Publication No. Hei 7-196 916, and Japanese Patent Laid-Open No. Hei 7-324132.

As described above, the solid electrolyte layer 13 is formed by applying a conductive polymer solution containing the conductive polymer satisfying the above condition (A) and satisfying the above condition (B) to the dielectric oxide film 12, and drying it. Founder. In the solid electrolyte layer 13 formed as described above, since the conductive polymer is sufficiently impregnated into the inside of the fine concavities and convexities of the dielectric oxide film 12, the capacitance performance of the obtained solid electrolytic capacitor 10 is improved.

The content of the conductive polymer in 100% by mass of the conductive polymer solution is preferably 9% by mass or less, and more preferably 5% by mass or less. When the content of the conductive polymer is 9% by mass or less, the wettability of the spacer formed in the film forming metal 11 in which the dielectric oxide film 12 is formed or in the wound solid electrolytic capacitor to be described later is improved. Therefore, the conductive polymer is not deposited on the surface of the dielectric oxide film 12, and can be sufficiently impregnated into the inside of the fine unevenness.

The lower limit of the content of the conductive polymer is not particularly limited, but is preferably 0.1% by mass or more from the viewpoint of easily forming the solid electrolyte layer 13 having a desired thickness.

Further, the surface tension of the conductive polymer solution is preferably less than 67 mN/m, more preferably 60 mN/m or less. When the surface tension of the conductive polymer solution is less than 67 mN/m, the film forming metal 11 having the dielectric oxide film 12 or the spacer provided in the wound solid electrolytic capacitor to be described later is wetted. Since the conductive polymer is not deposited on the surface of the dielectric oxide film 12, it can be sufficiently impregnated into the inside of the fine unevenness.

The lower limit of the surface tension of the conductive polymer solution is not particularly limited, but is preferably 20 mN/m or more.

The conductive polymer solution for forming the solid electrolyte layer 13 may contain, in addition to the conductive polymer, a conductive polymer (other conductive polymer) other than the conductive polymer, or an additive such as a surfactant. Other materials, etc.

As another conductive polymer, poly(3,4-ethylenedioxythiophene) is mentioned. Phenol), polypyrrole, polyaniline, and the like. Further, when these other conductive polymers are used, it is preferred to use a dopant (for example, polystyrenesulfonic acid or the like) in combination.

Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and a fluorine-based surfactant.

Examples of the anionic surfactant include alkylsulfonic acid, alkylbenzenesulfonic acid, alkylcarboxylic acid, alkylnaphthalenesulfonic acid, α-olefinsulfonic acid, dialkylsulfonic acid succinic acid, and α- Sulfonated fatty acid, N-methyl-N- oleyl taurine, petroleum sulfonic acid, alkyl sulfuric acid, sulfated fat, polyoxyethylene alkyl ether sulfuric acid, polyoxyethylene styrenated phenyl ether sulfuric acid, alkyl Phosphoric acid, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate, naphthalene sulfonic acid formaldehyde condensate, and the like.

Examples of the cationic surfactant include a first fatty amine to a third aliphatic amine, a quaternary ammonium, a tetraalkylammonium, a trialkylbenzylammonium alkylpyridinium, and a 2-alkyl-1-alkyl group. 1-hydroxyethylimidazolinium, N,N-dialkylmorpholinium, polyethylene polyamine fatty acid guanamine, urea polycondensate of polyurethane polyamine fatty acid guanamine, urea of polyethylene polyamine fatty acid guanamine The quaternary ammonium of the condensate, the salts thereof, and the like.

As the amphoteric surfactant, for example, N,N-dimethyl-N-alkyl-N-carboxymethylammonium betaine, N,N,N-trialkyl-N-sulfonic acid alkylammonium salt can be mentioned. Betaine, N,N-dialkyl-N,N-dipolyoxyethylene ammonium sulfate betaine, 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine and other betaines An aminocarboxylic acid such as an N,N-dialkylaminoalkylene carboxylate or the like.

Examples of the nonionic surfactant include polyoxyethylene oxide. Ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polystyrene phenyl ether, polyoxyethylene-polyoxypropylene diol, polyoxyethylene-polyoxypropylene alkyl ether, polyol fatty acid partial ester, polyoxygen Ethylene polyol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, polyoxyethylated castor oil, fatty acid diethanolamine, polyoxyethylene alkylamine, triethanolamine fatty acid partial ester, trialkyl oxide Amines, etc.

Examples of the fluorine-based surfactant include a fluoroalkylcarboxylic acid, a perfluoroalkylcarboxylic acid, a perfluoroalkylbenzenesulfonic acid, and a perfluoroalkylpolyoxyethyleneethanol.

Here, the alkyl group preferably has a carbon number of from 1 to 24, more preferably a carbon number of from 3 to 18.

These surfactants may be used alone or in combination of two or more.

When the conductive polymer solution contains a surfactant, the content of the surfactant in 100% by mass of the conductive polymer solution is preferably 0.1% by mass to 20% by mass, more preferably 0.1% by mass to 5% by mass. When the content of the surfactant is 0.1% by mass or more, the surface tension of the conductive polymer solution can be lowered. Thereby, the impregnation property of the inside of the fine unevenness of the dielectric oxide film 12 is improved, and the electrical conductivity of the solid electrolyte layer 13 is improved. On the other hand, when the content of the surfactant is 20% by mass or less, the conductivity can be favorably maintained.

(graphite layer)

The graphite layer 14 is a layer formed by applying a graphite liquid onto the solid electrolyte layer 13 or immersing the film forming metal 11 in which the dielectric oxide film 12 and the solid electrolyte layer 13 are sequentially formed in a graphite liquid.

(metal layer)

As the metal layer 15, in addition to the silver layer such as silver, there are mentioned: Aluminum electrode, tantalum electrode, tantalum electrode, titanium electrode, zirconium electrode, magnesium electrode, tantalum electrode, and the like.

In the solid electrolytic capacitor 10 of the present invention described above, the conductive polymer solution containing the conductive polymer satisfying the above condition (A) and satisfying the above condition (B) is used to form the solid electrolyte layer 13, and thus the solid electrolyte layer 13 is formed. The conductive polymer is sufficiently impregnated into the inside of the fine concavities and convexities of the dielectric oxide film 12. Thereby, the solid electrolyte layer 13 is formed to the inside of the fine unevenness of the dielectric oxide film 12, so that the capacitance expression rate is high.

<Method of Manufacturing Solid Electrolytic Capacitor>

Next, an example of a method of manufacturing the solid electrolytic capacitor 10 described above will be described.

The method for producing a solid electrolytic capacitor according to the present invention includes a method in which a conductive polymer solution containing the conductive polymer satisfying the above condition (A) and satisfying the above condition (B) is applied onto the surface of the film forming metal 11 a step (coating step) on the dielectric oxide film 12; and a step of drying the applied conductive polymer solution to form the solid electrolyte layer 13 (drying step).

In the present invention, the steps other than the step of forming the solid electrolyte layer 13 can be carried out by a known technique. For example, when the solid electrolytic capacitor 10 shown in FIG. 1 is produced, the vicinity of the surface layer of the film forming metal 11 such as aluminum foil is made porous by etching, and then the dielectric oxide film 12 is formed by anodization. Then, after the solid electrolyte layer 13 is formed on the dielectric oxide film 12, it is immersed in a graphite liquid, or a graphite liquid is applied to form a graphite layer 14 on the solid electrolyte layer 13, and a metal is formed on the graphite layer 14. Floor 15. Further, an external terminal (not shown) is connected to the cathode and the anode (not shown) and packaged to form a solid electrolytic capacitor 10.

Here, the step of forming the solid electrolyte layer 13 will be described in detail.

The solid electrolyte layer 13 can be formed by applying the conductive polymer solution containing the conductive polymer satisfying the above condition (A) and satisfying the above condition (B) to the surface of the film forming metal 11 On the formed dielectric oxide film 12 (coating step), the conductive polymer is impregnated into the fine concavities and convexities of the dielectric oxide film 12, and then dried (drying step).

Further, in the present invention, "coating" means forming a coating film (layer), and coating also includes coating or dipping.

The conductive polymer solution can be obtained by dissolving a conductive polymer, and optionally other conductive polymer, a dopant, or an additive such as a surfactant in a solvent.

In one embodiment of the present invention, the conductive polymer solution is obtained in a form of 100% by mass of the conductive polymer solution, and the content of the conductive polymer is 9% by mass or less, and more preferably 5% by mass or less. Adjustment.

When the content of the conductive polymer is 9% by mass or less, the wettability of the spacer formed in the film forming metal 11 in which the dielectric oxide film 12 is formed or in the wound solid electrolytic capacitor to be described later is improved. Therefore, the conductive polymer is not deposited on the surface of the dielectric oxide film 12, and can be sufficiently impregnated into the inside of the fine unevenness.

The lower limit of the content of the conductive polymer is not particularly limited, but From the viewpoint of easily forming the solid electrolyte layer 13 having a desired thickness, it is preferably 0.1% by mass or more.

Further, in another embodiment of the present invention, the conductive polymer solution is adjusted by a method in which the surface tension is less than 67 mN/m, more preferably 60 mN/m or less.

When the surface tension of the conductive polymer solution is less than 67 mN/m, the film forming metal 11 having the dielectric oxide film 12 or the spacer provided in the wound solid electrolytic capacitor to be described later is wetted. Since the conductive polymer is not deposited on the surface of the dielectric oxide film 12, it can be sufficiently impregnated into the inside of the fine unevenness.

The lower limit of the surface tension of the conductive polymer solution is not particularly limited, but is preferably 20 mN/m or more.

The surface tension of the conductive polymer solution can be adjusted by the type or content of the conductive polymer, the type of the solvent, and the like.

As a solvent used for the conductive polymer solution, water, an organic solvent, and a mixed solvent of water and an organic solvent are used, and the details will be described later. For example, when a mixed solvent is used as the solvent, the ratio of the organic solvent tends to increase, and the surface tension of the conductive polymer solution tends to be low.

Further, the surface tension of the conductive polymer solution can also be adjusted by blending the above surfactant. In particular, when only water is used as the solvent, the surface tension of the conductive polymer solution tends to be high. In this case, the surface tension can be lowered by blending the surfactant.

Furthermore, the surface tension of the conductive polymer solution is measured by a flat surface method (Wilhelmy Method) using an automatic surface tension meter. The value is fixed.

In other words, the measuring instrument (platinum plate) is attached to the measurement solution, and the surface is measured by the displacement of the measuring element in the solution when the force (surface tension) of the solution is stretched by the solution and the force of the spring of the fixed measuring element is measured. tension.

Examples of the solvent used in the conductive polymer solution include water, an organic solvent, and a mixed solvent of water and an organic solvent.

Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, propanol, and butanol; and ketones such as acetone, methyl ethyl ketone, ethyl isobutyl ketone, and methyl isobutyl ketone; Ethylene glycols such as diol, ethylene glycol methyl ether, ethylene glycol mono-n-propyl ether; propylene glycol such as propylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, propylene glycol propyl ether; dimethylformamide, two Amidoxime such as methyl acetamide; pyrrolidone such as N-methylpyrrolidone or N-ethylpyrrolidone; methyl lactate, ethyl lactate, methyl β-methoxyisobutyrate, A hydroxyester such as methyl α-hydroxyisobutyrate or γ-butyrolactone. These organic solvents may be used alone or in combination of two or more. Among these, from the viewpoint of water solubility and handling, alcohols are preferred, and methanol or isopropyl alcohol is particularly preferred.

When a mixed solvent is used as the solvent, the content of the organic solvent in 100% by mass of the mixed solvent is preferably from 4% by mass to 70% by mass, more preferably from 10% by mass to 50% by mass. When the content of the organic solvent is within the above range, the conductive polymer is well dissolved.

Examples of the method for applying the conductive polymer solution include dip coating, brush coating, spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, and wire rod. Coating method, spray coating method, flow coating method, screen printing Brush method, fast drying printing method, lithography method, inkjet printing method, and the like. In particular, from the viewpoint of easy handling, a dip coating method (dipping method) is preferred.

When the conductive polymer solution is applied by the dip coating method, the immersion time in the conductive polymer solution is preferably from 1 minute to 30 minutes from the viewpoint of workability. Further, when dip coating is carried out, it is also effective to return to normal pressure after immersion under reduced pressure or to pressurize during immersion.

However, the conductive polymer may impregnate the conductive polymer into the fine concavities and convexities of the dielectric oxide film 12 by a physical force from the outside, but the initial investment of the mechanical device may increase or the conductive polymer may be The solution easily scatters to a portion other than the dielectric oxide film 12, and the utilization ratio of the conductive polymer is likely to decrease.

However, in the present invention, since the conductive polymer solution is used for coating, the conductive polymer is easily impregnated into the fine concavities and convexities of the dielectric oxide film 12. Therefore, even if the spraying method or the like is not used, the operation is easy, the initial investment is not easily increased, and the dip coating method capable of effectively utilizing the conductive polymer can be used, which is economically advantageous.

The drying method after applying the conductive polymer solution is preferably heat drying, and for example, a method of air drying or rotating and physically drying may be used.

Further, the drying conditions are determined by the type of the conductive polymer or the solvent. Usually, the drying temperature is preferably from 20 ° C to 190 ° C from the viewpoint of drying property, and the drying time is preferably from 1 minute to 30 minutes.

In the method for producing a solid electrolytic capacitor of the present invention described above, the conductive polymer satisfying the above condition (A) is contained and satisfied. Since the conductive polymer solution of the above condition (B) is applied onto the dielectric oxide film formed on the film-forming metal to form a solid electrolyte layer, the conductive polymer is sufficiently impregnated into the fine unevenness of the dielectric oxide film. So far inside. Thereby, a solid electrolyte layer having a high conductivity can be formed on the dielectric oxide film, whereby a solid electrolytic capacitor having a high capacitance performance can be easily manufactured.

In particular, when the content of the conductive polymer in the conductive polymer solution or the surface tension of the conductive polymer solution is adjusted to a specific value, the conductive polymer is more likely to be impregnated into the fine film of the dielectric oxide film. The inside of the bumps.

In addition, in recent years, the porous film-forming metal is further refined or has fine pores of various forms, so that the inside of the dielectric oxide film is finer and more complicated, but in the case of the present invention, it is also possible to conduct electricity. The polymer is sufficiently impregnated into the interior of a finer and more complicated dielectric oxide film.

In the solid electrolytic capacitor obtained by the present invention, the solid electrolyte layer in which the conductive polymer is sufficiently impregnated into the fine concavities and convexities is formed on the dielectric oxide film, so that the capacitance is high and the capacitor is used as a capacitor. Excellent performance.

Further, in the present invention, chemical vapor polymerization or electrolytic polymerization is not performed on the dielectric oxide film to form a solid electrolyte layer, so that impurities in the solid electrolyte layer are small, and the production steps are not easily complicated.

Further, although the aluminum is exemplified as the film-forming metal, the aluminum may be exemplified as the ruthenium, the ruthenium, the nickel-plated product, and the like, and is not particularly limited to aluminum.

<Other embodiment examples>

The method for producing the solid electrolytic capacitor of the present invention is not limited to the above embodiment.

In the above embodiment, the conductive polymer solution is directly applied onto the dielectric oxide film formed on the film-forming metal to form a solid electrolyte layer. However, the conductive polymer solution may be applied before the application of the conductive polymer solution. A step of coating an organic solvent or a mixed solvent of an organic solvent and water on the dielectric oxide film (first impregnation step).

The organic solvent used for the first impregnation step may, for example, be an organic solvent exemplified as a solvent for the conductive polymer solution. When the mixed solvent is used in the preliminary impregnation step, the content of the organic solvent in 100% by mass of the mixed solvent is preferably 10% by mass or more.

In addition, as a coating method of the organic solvent or the mixed solvent in the first immersion step, various coating methods exemplified as the coating method of the conductive polymer solution are mentioned.

In the embodiment, after the first immersion step, a conductive polymer solution containing a conductive polymer solution is applied onto the dielectric oxide film coated with the organic solvent or the mixed solvent (coating step), and then The coated conductive polymer solution is dried to form a solid electrolyte layer (drying step).

When the first impregnation step is performed, the conductive polymer contained in the conductive polymer solution used in the coating step does not necessarily need to satisfy the above condition (A), and the conductive polymer solution does not necessarily need to satisfy the above condition (B). The reason for this is considered to be that the conductive polymer solution forms a metal with respect to the film on which the dielectric oxide film is formed by performing the first immersion step, or a winding type to be described later. In the solid electrolytic capacitor, the wettability of the separator is improved. Therefore, even if a conductive polymer solution containing a conductive polymer that does not satisfy the above condition (A) is used, or a conductive material that does not satisfy the above condition (B) is used. The polymer solution and the conductive polymer are not deposited on the surface of the dielectric oxide film, but are impregnated into the interior of the fine concavities and convexities. However, in order to further improve the impregnation property of the conductive polymer, it is preferred to use a conductive polymer solution containing the conductive polymer satisfying the above condition (A) and satisfying the above condition (B), and more preferably The content of the conductive polymer in the conductive polymer solution is adjusted to 9% by mass or less, or the surface tension of the conductive polymer solution is adjusted to less than 67 mN/m.

Further, the solid electrolytic capacitor of the present invention is not limited to the above embodiment.

The solid electrolytic capacitor is a laminated solid electrolytic capacitor. For example, the solid electrolytic capacitor of the present invention may be provided with a spacer between a film forming metal (anode) having a dielectric oxide film formed thereon and a graphite layer and a metal layer (cathode). . As the solid electrolytic capacitor in which a separator is provided between the anode and the cathode, a wound solid electrolytic capacitor 20 as shown in Fig. 2 can be cited.

Further, in Fig. 2, reference numeral 21 is "anode", reference numeral 22 is "cathode", and reference numeral 23 is "spacer".

The wound-type solid electrolytic capacitor 20 can be obtained by providing a spacer 23 between the anode 21 and the cathode 22, and winding the same to form a wound body, and the above-mentioned laminated type solid electrolytic capacitor Solid electrolyte formed on the dielectric oxide film formed on the film-forming metal The layer (not shown) is further connected to the external terminal 24 on the anode 21 and the cathode 22 to be packaged. When the conductive polymer solution is applied onto the dielectric oxide film, a dip coating method is preferred.

Further, after the spacer 23 is provided between the anode 21 and the cathode 22, a solid electrolyte layer may be formed on the dielectric oxide film formed on the film forming metal in the same manner as the above-mentioned laminated solid electrolytic capacitor, and then These are wound to form a wound body.

The material of the separator 23 used in the wound solid electrolyte capacitor 20 is, for example, fiber, paper, polyethylene terephthalate or the like.

Further, as the spacer 23, a spacer in which insulating oil is infiltrated may be used. Examples of the insulating oil include mineral oil, diallyl ethane oil, alkylbenzene oil, aliphatic ester oil (maleate ester, fumarate, etc.), and aromatic An electrical insulating oil such as a steroid oil (such as a phthalate), a polycyclic aromatic oil or a polyoxygenated oil, or a mixture thereof.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited to the examples.

<Manufacture of Conductive Polymer>

. A-1: Production of poly(2-sulfonic acid-5-methoxy-1,4-iminobenzene)

100 mmol of 2-aminoanisole-4-sulfonic acid was stirred and dissolved in water containing 100 mmol of triethylamine at 25 ° C, and then an aqueous solution of 100 mmol of ammonium peroxodisulfate was added dropwise. After completion of the dropwise addition, the mixture was further stirred at 25 ° C for 12 hours, and then the reaction product was filtered off and washed. Thereafter, it is dried to obtain a powdery poly(2-sulfonic acid-5-methoxy-1,4-imidobenzene). (A-1) 15g. The volume average particle diameter of the obtained A-1 was 0.95 nm, and the volume resistance value was 9.0 Ω. Cm. Further, the mass average molecular weight determined by gel permeation chromatography (GPC) and converted from sodium polystyrene sulfonate was about 10,000.

The volume average particle diameter of A-1 was determined in the following manner.

First, a conductive polymer solution having a concentration of A-1 of 1% by mass was prepared, and then a dynamic light scattering type particle size measuring device ("Nanotrac UPA-UT" manufactured by Nikkiso Co., Ltd.) was used and dynamic light was used. The particle distribution was measured by a scattering method and corrected for the viscosity of pure water. Among the one or more peaks obtained, the volume average particle diameter of the smallest particle distribution of the peak having the smallest particle diameter is determined as the volume average particle diameter of the conductive polymer.

Further, since the particle distribution of A-1 obtained by the dynamic light scattering method has one peak, the particle distribution is directly corrected as the minimum particle distribution, and the volume average particle diameter is determined.

<Preparation of Conductive Polymer Solution (B-1 to B-21)>

. B-1: A-1 (3 mass%) and water (97 mass%) as a solvent were mixed.

. B-2: sodium dioctylsulfonate succinate ("Pelex OT-P" manufactured by Kao Co., Ltd.) (0.1% by mass) mixed with A-1 (3 mass%) as a surfactant, And water as a solvent (96.9 mass%).

. B-3: A-1 (3 mass%) and a mixed solvent of water and isopropyl alcohol (IPA) (mass ratio: 4:1) (97 mass%) were mixed.

. B-4: Mixed with A-1 (5 mass%), and water as solvent and IPA (mixing solvent of mass ratio 4:1) (95 mass%).

. B-5: A-1 (8 mass%) and water (92 mass%) as a solvent were mixed.

. B-6: A-1 (10% by mass), sodium dioctylsulfonate succinate (0.1% by mass) as a surfactant, and water (89.9 mass%) as a solvent were mixed.

. B-7: A-1 (5 mass%), sodium dioctylsulfonic acid sodium succinate (0.5 mass%) as a surfactant, and water (94.5 mass%) as a solvent were mixed.

. B-8: Mixed solvent (mass ratio: 1:1) (92% by mass) of A-1 (8 mass%) and water and methanol (MeOH) as a solvent.

. B-9: A-1 (10% by mass) and water (90% by mass) as a solvent were mixed.

. B-10: A-1 (9.1% by mass) and water (90.9% by mass) as a solvent were mixed.

. B-11: a mixed solvent of A-1 (4.8% by mass) and water as a solvent and IPA (mass ratio: 1:1) (95.2% by mass).

. B-12: A mixed solvent (95.2% by mass) of water and acetone (mass ratio: 1:1) as a solvent was mixed with A-1 (4.8% by mass).

. B-13: A mixed solvent (95.2% by mass) of water and MeOH (mass ratio: 1:1) as a solvent was mixed with A-1 (4.8% by mass).

. B-14: A mixed solvent (95.2% by mass) of water and MeOH (mass ratio: 9:1) as a solvent was mixed with A-1 (4.8% by mass).

. B-15: mixed with A-1 (4.8% by mass), and water as a solvent A mixed solvent of MeOH (mass ratio: 3:1) (95.2% by mass).

. B-16: A-1 (4.8% by mass), sodium dioctylsulfonate sodium succinate (0.5% by mass) as a surfactant, and water (94.7 mass%) as a solvent were mixed.

. B-17: A-1 (4.8% by mass) and water (95.2% by mass) as a solvent were mixed.

. B-18: A mixed solvent (97.1% by mass) of water and MeOH (mass ratio: 4:1) as a solvent was mixed with A-1 (2.9% by mass).

. B-19: A-1 (2.9% by mass), sodium dioctylsulfonate sodium succinate (0.1% by mass) as a surfactant, and water (97.0% by mass) as a solvent were mixed.

. B-20: A mixed solvent (97.1% by mass) of A-1 (2.9% by mass) and water as a solvent and IPA (mass ratio: 4:1) was mixed.

. B-21: PEDOT (poly(3,4-ethylenedioxythiophene)) aqueous solution (manufactured by Clevios, "PH510", PEDOT has a volume average particle diameter of 26.7 nm and a concentration of 1.2% by mass).

Further, in B-1 to B-20, A-1 was dissolved in a solvent, and in B-21, PEDOT was not dissolved in a solvent and dispersed. Further, the volume average particle diameter of PEDOT was determined in the same manner as in A-1.

(Measurement of surface tension of conductive polymer solution)

The surface tension of the conductive polymer solution (B-1 to B-21) was measured by a flat surface method (sheet method) using an automatic surface tension meter ("CBVP-Z type" manufactured by Kyowa Interface Science Co., Ltd.). It was measured in the following manner. The results are shown in Table 1.

In other words, the measuring instrument (platinum plate) is attached to the measurement solution, and the surface is measured by the displacement of the measuring element in the solution when the force (surface tension) of the solution is stretched by the solution and the force of the spring of the fixed measuring element is measured. tension.

<Example 1>

(Production of test piece 1: laminated Ta substrate)

A tantalum element (manufactured by High Purity Substance Co., Ltd., "tantalum capacitor anode element (particle)") having a dielectric oxide film was immersed in the conductive polymer solution (B-2) for 5 minutes. Thereafter, the tantalum element was taken out and dried by heating at 130 ° C for 15 minutes, and a solid electrolyte layer (having a thickness of about 10 μm from the surface of the dielectric oxide film) was formed on the dielectric oxide film. As test piece 1.

(Production of test piece 2: laminated Al substrate)

The wound aluminum capacitor was cut into a flag shape and anodized in an aqueous solution of ammonium adipate having a concentration of 3% by mass at a voltage of 5.7 V and a temperature of 70 ° C for 120 minutes to form dielectric oxide on the surface of the aluminum foil. Membrane to obtain an aluminum component. This aluminum element was immersed in the conductive polymer solution (B-2) for 5 minutes. Thereafter, the aluminum element was taken out and dried by heating at 105 ° C for 30 minutes, and a solid electrolyte layer (having a thickness of about 10 μm from the surface of the dielectric oxide film) was formed on the dielectric oxide film. As test piece 2.

(Production of test piece 3: wound Al substrate)

The wound aluminum element was immersed in the conductive polymer solution (B-2) for 5 minutes. Thereafter, the wound aluminum member was taken out and dried by heating at 105 ° C for 30 minutes to form a solid electrolyte layer on the dielectric oxide film, which was used as the test piece 3.

(Measurement of capacitance performance rate)

First, an aluminum oxide foil having a capacitance per unit area of 95 μF/cm ² was used, and a dielectric oxide film was formed on the surface of the aluminum foil in the same manner as the test piece 2. The solution was immersed in an aqueous solution of ammonium adipate having a concentration of 3% by mass, and a liquid at 120 Hz was measured using an Inductance Capacitance Resistance (LCR) meter ("E4980A Precision LCR Meter" manufactured by Agilent Technologies, Inc.). Medium capacity (maximum capacity (Cw)). As a result, the maximum capacitance (Cw) was 94 μF.

Further, using an aluminum foil having a capacitance per unit area of 95 μF/cm ² , a dielectric oxide film was formed on the surface of the aluminum foil in the same manner as the test piece 2, and a solid electrolyte layer was formed on the dielectric oxide film (from The surface of the dielectric oxide film has a thickness of about 10 μm. Then, a graphite layer and an aluminum electrode were formed on the solid electrolyte layer, and a cathode lead terminal was connected to the aluminum electrode to prepare a laminated aluminum solid electrolytic capacitor having a rated voltage of 6.3V.

With respect to the obtained laminated aluminum solid electrolytic capacitor, an electric capacity (Cs) at 120 Hz was measured using an LCR meter ("E4980A Precision LCR meter" manufactured by Agilent Technologies Co., Ltd.). Then, the capacitance expression rate of the laminated aluminum solid electrolytic capacitor was determined according to the following formula (i). The results are shown in Table 2.

Capacitance performance rate (%) = (Cs / Cw) × 100... (i)

(evaluation of impregnation)

The obtained test piece 1 to test piece 3 were cut in the longitudinal direction (stacking direction), respectively, using a scanning electron microscope (Hitachi Advanced Technology Co., Ltd. In the "S-4300SE/N", the test piece was observed at an observation magnification of 1000 times to 30,000 times, and the state of impregnation of the conductive polymer in the fine unevenness of the dielectric oxide film was confirmed. The evaluation of the impregnation property was carried out by the evaluation criteria shown below. In addition, the case of "○" is 5 points, the case of "○" is 3 points, the case of "△" is 1 point, and the case of "X" is 0 point, total test piece 1 The results of the test piece 3 were evaluated as a comprehensive evaluation. The results of these are shown in Table 2.

◎: The conductive polymer is sufficiently impregnated into the inside of the fine concavities and convexities of the dielectric oxide film.

○: The conductive polymer was impregnated into the inside of the fine concavities and convexities of the dielectric oxide film.

△: The impregnation of the conductive polymer into the inside of the fine concavities and convexities of the dielectric oxide film is slightly insufficient.

X: The conductive polymer is insufficiently impregnated into the inside of the fine concavities and convexities of the dielectric oxide film.

<Example 2 to Example 15, Example 18 to Example 20, Comparative Example 1 to Comparative Example 3>

Test piece 1 to test piece 3 were produced in the same manner as in Example 1 except that the conductive polymer solution of the type shown in Table 2 was used, and the measurement of the capacitance expression rate and the evaluation of the impregnation property were performed. The results are shown in Table 2.

<Example 16>

The conductive polymer solution (B-1) was used, and the ruthenium element, the aluminum element, and the wound aluminum element were each immersed in the IPA for 1 minute before being immersed in the conductive polymer solution, respectively. In the same way as in Example 1. In the manner, the test piece 1 to the test piece 3 were produced, and the measurement of the capacitance expression rate and the evaluation of the impregnation property were performed. The results are shown in Table 2.

<Example 17>

The conductive polymer solution (B-1) was used, and the ruthenium element, the aluminum element, and the wound aluminum element were each immersed in MeOH for 1 minute before being immersed in the conductive polymer solution, respectively. Test piece 1 to test piece 3 were produced in the same manner as in Example 1, and measurement of capacitance expression rate and evaluation of impregnation property were performed. The results are shown in Table 2.

As is clear from the results of Table 2, in the case of each example, the conductive polymer was substantially impregnated into the inside of the fine concavities and convexities of the dielectric oxide film.

Further, when Examples 16 to 18 were compared, the evaluation of the impregnation properties of Examples 16 and 17 in which the first impregnation step was carried out was more favorable.

On the other hand, in the case of Comparative Example 1 and Comparative Example 2 in which the conductive polymer solution which does not satisfy the condition (B) is used, and the conductive polymer which does not satisfy the condition (A) is used, the condition is not satisfied. In the case of Comparative Example 3 of the conductive polymer solution of (B), it is difficult for the conductive polymer to be impregnated into the fine concavities and convexities of the dielectric oxide film.

10‧‧‧Solid electrolytic capacitor

11‧‧‧film forming metal

12‧‧‧Dielectric oxide film

13‧‧‧Solid electrolyte layer

14‧‧‧ graphite layer

15‧‧‧metal layer

20‧‧‧Solid electrolytic capacitor

21‧‧‧Anode

22‧‧‧ cathode

23‧‧‧ spacers

24‧‧‧External terminals

P1~P3‧‧‧Crest

S‧‧‧ area

Fig. 1 is a cross-sectional view schematically showing an example of a solid electrolytic capacitor of the present invention.

Fig. 2 is a perspective view schematically showing another example of the solid electrolytic capacitor of the present invention.

Fig. 3 is a view schematically showing a particle distribution of a conductive polymer measured by a dynamic light scattering method.

10‧‧‧Solid electrolytic capacitor

11‧‧‧film forming metal

12‧‧‧Dielectric oxide film

13‧‧‧Solid electrolyte layer

14‧‧‧ graphite layer

15‧‧‧metal layer

Claims (11)

A solid electrolytic capacitor in which a solid electrolyte layer is formed, and a conductive polymer solution containing a conductive polymer satisfying the following condition (A) and satisfying the following condition (B) is applied to the film. Forming a dielectric oxide film formed on the surface of the metal and drying it, and the dielectric oxide film does not have a chemical oxidation polymerization or electrolysis on the dielectric oxide film. The solid electrolyte layer formed by the polymerization; the condition (A): one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive polymer solution containing 1% by mass of the conductive polymer The volume average particle diameter of the smallest particle distribution of the peak having the smallest particle diameter is 5 nm or less; and the condition (B): forming the conductive polymer solution containing the conductive polymer to have a capacitance of 95 μF/cm ² A capacitance type of the laminated aluminum solid electrolytic capacitor when a laminated aluminum solid electrolytic capacitor is fabricated on a dielectric oxide film formed on the surface of aluminum and dried to form a solid electrolyte layer The current rate is over 70%. The solid electrolytic capacitor according to the first aspect of the invention, wherein the content of the conductive polymer in the conductive polymer solution is 9% by mass or less. The solid electrolytic capacitor according to claim 1, wherein the conductive polymer solution has a surface tension of less than 67 mN/m. As claimed in any one of claims 1 to 3 A bulk electrolytic capacitor, wherein the conductive polymer solution contains a surfactant. The solid electrolytic capacitor according to claim 1, wherein the conductive polymer has a repeating unit represented by the following formula (1): In the formula (1), R ¹ to R ⁴ are each independently -H, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. Or a salt thereof, a hydroxyl group, a nitro group, -F, -Cl, -Br or -I, and at least one of R ¹ to R ⁴ is an acidic group or a salt thereof; here, the acidic group means a sulfonic acid group or a carboxyl group . A method for producing a solid electrolytic capacitor, comprising: coating a conductive polymer solution containing a conductive polymer satisfying the following condition (A) and satisfying the following condition (B) on a surface of a film forming metal; The dielectric oxide film does not have a step of forming a solid electrolyte layer by chemical oxidative polymerization or electrolytic polymerization on the dielectric oxide film: Condition (A): including use of 1% by mass of conductivity Among the one or more peaks obtained by measuring the particle distribution by the dynamic light scattering method, the volume average particle diameter of the smallest particle distribution of the peak having the smallest particle diameter is 5 nm or less; B): A solid electrolyte layer formed by applying a conductive polymer solution containing a conductive polymer onto a dielectric oxide film formed on the surface of aluminum having a capacitance of 95 μF/cm ² and drying the same When a laminated aluminum solid electrolytic capacitor is produced, the capacitance performance of the laminated aluminum solid electrolytic capacitor is 70% or more; and the applied conductive polymer solution is dried to form Solid electrolyte layer. The method for producing a solid electrolytic capacitor according to the sixth aspect of the invention, wherein the content of the conductive polymer in the conductive polymer solution is 9% by mass or less. The method for producing a solid electrolytic capacitor according to claim 6, wherein the conductive polymer solution has a surface tension of less than 67 mN/m. A method for producing a solid electrolytic capacitor, comprising: applying an organic solvent or a mixed solvent of an organic solvent and water to a dielectric oxide film formed on a surface of a film forming metal; and coating an organic solvent or an organic solvent with On the dielectric oxide film of the mixed solvent of water, a conductive polymer satisfying the following condition (A) is applied, and a conductive polymer solution satisfying the following condition (B); and a coated conductive material are applied. The polymer solution is dried to form a solid electrolyte layer, and does not have a step of forming a solid electrolyte layer by chemical oxidative polymerization or electrolytic polymerization on the dielectric oxide film; Condition (A): containing 1 mass used Among the one or more peaks obtained by measuring the particle distribution by the dynamic light scattering method, the conductive polymer solution of the conductive polymer has a volume average particle diameter of 5 nm which is the smallest particle distribution of the peak having the smallest particle diameter. And (B): a dielectric oxide film formed by applying a conductive polymer solution containing a conductive polymer to a surface of aluminum having a capacitance of 95 μF/cm ² When the laminated solid aluminum electrolytic capacitor is produced by the solid electrolyte layer which is dried and dried, the capacitance performance of the laminated aluminum solid electrolytic capacitor is 70% or more. The method for producing a solid electrolytic capacitor according to the invention of claim 9, wherein the content of the conductive polymer in the conductive polymer solution is 9% by mass or less. The method for producing a solid electrolytic capacitor according to claim 9, wherein the conductive polymer solution has a surface tension of less than 67 mN/m.