JP4826237B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

The present invention relates to a solid electrolytic capacitor using a conductive polymer as a solid electrolyte layer and a method for manufacturing the same.

  As shown in FIG. 1, a basic element of a solid electrolytic capacitor is generally formed by forming a dielectric oxide film layer (2) on an anode substrate (1) made of a metal foil having a large specific surface area that has been subjected to etching treatment. A solid semiconductor layer (hereinafter referred to as “solid electrolyte”) (4) is formed as an opposing electrode, and more preferably, a conductive layer (5) such as a conductive paste is formed on the semiconductor layer. The Then, such an element is singly or laminated to join the lead wires (6, 7), and the whole is completely sealed with an epoxy resin (8) or the like to be widely used as a capacitor (9) component in a wide range of electrical products. in use.

  In recent years, with the digitization of electrical equipment and the speeding up of personal computers, small and large-capacitance capacitors and low-impedance capacitors in the high-frequency region are required. Recently, it has been proposed to use a conductive polymer having electronic conductivity as a solid electrolyte.

  In general, electrolytic oxidation polymerization and chemical oxidation polymerization are known as methods for forming a conductive polymer on a dielectric oxide film. In the chemical oxidation polymerization method, it is difficult to control the reaction or the form of the polymer film, but various methods have been proposed because the formation of a solid electrolyte is easy and mass production is possible in a short time. For example, there has been proposed a method of forming a solid electrolyte having a layered structure by alternately repeating a step of immersing the anode substrate in a solution containing a monomer and a step of immersing the anode substrate in a solution containing an oxidizing agent (Patent Document 1). According to this method, a solid electrolytic capacitor having a high capacity, low impedance, and excellent heat resistance can be manufactured by forming a solid electrolyte layer having a layered structure with a film thickness of 0.01 to 5 μm. However, there is a problem that a space portion between layers of the layered structure portion forming the solid electrolyte layer is large. Therefore, as an element for a multilayer capacitor in which a plurality of capacitor elements are stacked, a further reduction in thickness of the entire solid electrolyte layer is required.

  As a method of forming a solid electrolyte in the pores and outer surfaces of the capacitor element without forming a solid electrolyte layer having a layered structure, the anode substrate is immersed in a solution containing a monomer compound and then polymerized in an oxidant solution. A method of repeating a drying cycle after washing an oxidizing agent has been proposed (Patent Document 2). However, the solid electrolyte layer formed by this method has insufficient resistance to external stress because there is no space between the layers.

Conventionally, increasing the capacity of a capacitor has been realized by using a winding type or a multilayer type. For example, in an aluminum electrolytic capacitor, a method for forming a solid electrolyte in a state where a large-area aluminum foil and a separator are wound up has been proposed. However, this method could not produce a thin large-capacity capacitor. . As another method for increasing the capacity of a capacitor, a method of stacking a plurality of capacitor elements and a method of arranging a plurality of small elements in parallel have been proposed.
Further, as a method of increasing the capacity of a capacitor, increasing the area of the element itself by chemical polymerization has a problem that the solid electrolyte cannot be formed uniformly as the area increases.

  By the way, a solid electrolyte comprising forming a conductive polymer film by chemical oxidative polymerization having a step of applying or spraying a solution containing an oxidizing agent, and further laminating the conductive polymer film by electrolytic polymerization thereon A method for forming a layer has been proposed (Patent Documents 3 and 4). According to the proposed method, it is said that a solid electrolyte having high capacitance and good electrical characteristics can be obtained.

Japanese Patent No. 3187380 JP 09-306788 A JP 63-173313 A Japanese Patent Laid-Open No. 04-369819

In order to form a solid electrolyte uniformly on the surface of a sheet-shaped valve metal substrate having a large area, it has been conventionally necessary to combine a chemical polymerization method and an electrolytic polymerization method. However, the economic burden is large. It was. Further, when a solid electrolyte is formed by a chemical polymerization method, the production of a conductive polymer that constitutes the cathode portion of the capacitor element must be performed under carefully controlled conditions. When this control is incomplete, the thickness of the conductive polymer becomes non-uniform, and in the thin part, the paste or the like is likely to be in direct contact with the dielectric oxide film layer, leading to an increase in leakage current. Therefore, it has been difficult to manufacture a capacitor element having a large area with a high yield.

In view of the above circumstances, an object of the present invention is to form a conductive polymer film having a uniform thickness over a wide area, and thus to obtain a capacitor element having a low leakage current even in a large area. It is to provide a manufacturing method that can be used.

As a result of intensive studies to achieve the above object, the present inventors have polymerized a monomer in the presence of an oxidant on a dielectric film formed on the surface of a valve action metal having micropores, thereby forming a solid electrolyte layer. In addition to the step of spraying a liquid containing a monomer (hereinafter abbreviated as “step 1”) and the step of spraying a liquid containing an oxidizing agent (hereinafter abbreviated as “step 2”), was briefly immersed in a liquid containing no oxidizing agent, the drying step (hereinafter, abbreviated as "step 3".) gastric line, by repeating several times the cycle including these, polymers and polymer layers having a layer structure It has been found that the gap (space) between them is very narrow, and a solid electrolyte is formed that is dense and excellent in shape stability and in which leakage current is remarkably suppressed. Based on this finding, the present invention has been completed.

In chemical oxidative polymerization in which a cycle comprising a monomer-containing liquid spraying step (step 1) and an oxidizing agent-containing liquid spraying step (step 2) is repeated, the resulting solid electrolyte necessarily has a layered structure. The oxidant layer sandwiched between the polymer layer and the polymer layer is finally removed as an unnecessary layer in the cleaning process and changed into a space layer. The final shape of the solid electrolyte is determined by the thickness of the space layer. From this, it is possible to complete the polymerization reaction with the remaining oxidizing agent even if the oxidizing agent is partially removed by immersing it in a solution containing no oxidizing agent for a short time, and a dense layered structure is formed. .

It has been found that the solid electrolytic capacitor thus obtained has improved adhesion of the solid electrolyte formed on the dielectric film, high capacity, low dielectric loss (tan δ) and leakage current.
Furthermore, it was confirmed that the capacitor can be reduced in size and increased in capacity by stacking a plurality of solid electrolytic capacitor elements having excellent characteristics. It was also confirmed that the capacity could be increased by forming a solid electrolyte uniformly on the surface of a large-area valve metal.

Thus, according to the present invention, the following (1) to ( 9 ) solid electrolytic capacitor production methods and the following (10) and (11) solid electrolytic capacitors are provided.
(1) In a method for producing a solid electrolytic capacitor in which a monomer film is polymerized with an oxidizing agent on a dielectric film formed on a valve-acting metal surface having fine pores, and a solid electrolyte layer containing a conductive polymer composition is provided. A step of spraying a liquid containing a monomer on the dielectric film formed on the surface of the valve metal and then drying (step 1), a step of spraying a liquid containing an oxidizing agent and then drying (step 2). And the solid electrolyte layer is provided by a method of repeating a cycle including a step (step 3) of dipping in a solution capable of dissolving an oxidant, holding for 0.1 to 120 seconds , and then drying (step 3). A method for producing a solid electrolytic capacitor.

( 2 ) The method for producing a solid electrolytic capacitor as described in (1) above, wherein the cycle comprising Step 1, Step 2 and Step 3 is repeated a plurality of times, and then the cycle comprising Step 1 and Step 2 is repeated a plurality of times.
( 3 ) The method for producing a solid electrolytic capacitor according to (1) or (2) above, wherein the liquid capable of dissolving the oxidizing agent is water or an aqueous solution of a dopant compound and / or a surfactant.

( 4 ) The manufacturing method of the solid electrolytic capacitor in any one of said (1)-( 3 ) whose oxidizing agent is a persulfate.
( 5 ) The method for producing a solid electrolytic capacitor according to any one of (1) to ( 4 ), wherein the liquid capable of dissolving the oxidizing agent is a suspension containing organic fine particles.

(6) Average particle size of the organic fine particles _{(D 50)} The method for producing a solid electrolytic capacitor according to the above (6) is in the range of 0.1 to 20 [mu] m.
( 7 ) The above organic fine particles are at least one selected from the group consisting of aliphatic sulfonic acid compounds, aromatic sulfonic acid compounds, aliphatic carboxylic acid compounds, aromatic carboxylic acid compounds, salts thereof, and peptide compounds. ( 6 ) The manufacturing method of the solid electrolytic capacitor as described in.
( 8 ) The manufacturing method of the solid electrolytic capacitor in any one of said (1)-( 7 ) in which the liquid containing an oxidizing agent contains surfactant further.

( 9 ) The method for producing a solid electrolytic capacitor according to any one of (1) to ( 8 ), wherein the valve action metal having a dielectric film layer that is flat is rotated and sprayed.
( 10 ) A solid electrolytic capacitor produced by the production method according to any one of (1) to ( 9 ) above.
( 11 ) A solid electrolyte layer containing a conductive polymer composition by the production method according to any one of (1) to ( 8 ) above on one surface of a valve metal having a flat dielectric film layer. Solid electrolytic capacitor provided.

  According to the present invention, there is less short circuit failure, less variation in element shape, stable production of a thin capacitor element, an increase in the number of capacitor elements in a solid electrolytic capacitor chip, a higher capacity, and an equivalent series resistance. It is possible to provide a solid electrolytic capacitor element suitable for a multilayer solid electrolytic capacitor having a small variation.

Hereinafter, the manufacturing method of the present invention will be described with reference to the accompanying drawings.
The dielectric film (2) on the surface of the anode substrate (1) used in the present invention is usually formed by subjecting a metal porous molded body having a valve action to chemical conversion treatment.
The metal having a valve action that can be used in the present invention is a simple metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, silicon, or an alloy thereof. Further, the porous form may be any form as long as it is a form of a porous molded body such as an etching product of a rolled foil or a fine powder sintered body.

  As the anode substrate (1), a porous sintered body of these metals, a plate (including ribbon, foil, etc.) surface-treated by etching or the like, a wire, etc. can be used. Is. Furthermore, a known method can be used as a method of forming the dielectric oxide film (2) on the surface of the porous metal body. For example, when an aluminum foil is used, an oxide film can be formed by anodizing in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or an ammonium salt thereof. Moreover, when using the sintered compact of a tantalum powder, it can anodize in phosphoric acid aqueous solution and can form an oxide film in a sintered compact.

For example, the thickness of the valve action metal foil varies depending on the purpose of use, but a foil having a thickness of about 40 to 300 μm is used. In order to obtain a thin solid electrolytic capacitor, for example, an aluminum foil having a thickness of 80 to 250 μm is preferably used, and the maximum height of the element provided with the solid electrolytic capacitor is preferably 250 μm or less. Although the size and shape of the metal foil vary depending on the application, a rectangular element having a width of about 1 to 50 mm and a length of about 1 to 50 mm is preferable as a flat element unit, more preferably about 2 to 15 mm in width and about 2 in length. ~ 25 mm.

Chemical conversion conditions such as chemical conversion liquid and chemical conversion voltage used for chemical conversion are confirmed in advance by experiments and set to appropriate values according to the capacity, withstand voltage, etc. required for the solid electrolytic capacitor to be produced. In addition, in the chemical conversion treatment, the chemical conversion solution is prevented from spreading to the portion that becomes the anode of the solid electrolytic capacitor, and the insulation from the solid electrolyte (4) (cathode portion) formed in the subsequent process is ensured. Generally, masking (3) is provided.

As a masking material, a general heat resistant resin, preferably a heat resistant resin which can be dissolved or swelled in a solvent or a precursor thereof, a composition comprising inorganic fine powder and a cellulose resin, etc. can be used, but the material is not limited. . Specific examples include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, etc.), low molecular weight polyimides and their Examples thereof include derivatives and precursors thereof, and low molecular weight polyimides, polyethersulfones, fluororesins and their precursors are particularly preferable.

The production method of the present invention includes a step 1 of spraying and drying a monomer-containing liquid on a dielectric film formed on the surface of a valve-acting metal porous substrate, a step 2 of spraying and drying an oxidant-containing liquid, and an oxidation process. It consists of performing a cycle including the step 3 of immersing and drying in a liquid not containing an agent (a liquid capable of dissolving an oxidizing agent) a plurality of times. In this manufacturing method, step 1 and step 2 may be performed first, regardless of whether the steps are first or second. Step 3 is performed immediately after step 2.

According to the present invention, by repeating the cycle consisting of Step 1 to Step 3 a plurality of times, the monomer concentration and the oxidant concentration gradually increase on the substrate, and chemical oxidative polymerization of the monomer occurs efficiently. In this chemical oxidative polymerization method, a monomer is deposited on the dielectric film having fine pores of the anode substrate, and oxidative polymerization is caused to occur in the presence of a compound that can be a dopant of the conductive polymer. Is formed on the dielectric surface as a solid electrolyte.

The solid electrolyte layer of the conductive polymer formed by the method of the present invention has a fibril structure or a lamellar (thin layered) structure, and in such a structure, there is a wide range of overlap between polymer chains. In the present invention, the total thickness of the solid electrolyte layer is in the range of about 10 to about 100 μm, and the space of the polymer layer structure is 0.01 to 5 μm, preferably 0.05 to 3 μm, more preferably 0.1. By making the space occupancy between each layer of the solid electrolyte occupying the entire polymer film within a range of ˜2 μm and within a range of 0.1-20%, electron hopping between polymer chains is facilitated and electric conductivity is improved. Improved characteristics such as low impedance.

Hereinafter, a method for forming a solid electrolyte layer on a dielectric film formed on a valve-acting metal surface having fine holes in the present invention will be described step by step.
The step 1 of spraying the monomer-containing liquid on the dielectric film formed on the valve-acting metal surface having micropores and then drying is to supply the monomer on the dielectric surface and on the polymer composition formed by polymerization. To be implemented. Further, in order to uniformly deposit the monomer on the dielectric surface and the polymer composition, the monomer-containing liquid is sprayed and then dried, that is, left in the air for a certain time to evaporate the solvent. The drying conditions vary depending on the type of the solvent, but are generally performed at a temperature from 0 ° C. or higher to the boiling point of the solvent. The standing time varies depending on the type of the solvent, but it is generally about 5 seconds to 15 minutes, for example, within 5 minutes for alcohol solvents. By providing this standing time, the monomer can be uniformly deposited on the dielectric surface, and further, the contamination of the oxidant-containing liquid can be reduced in the step 2 of spraying the oxidant-containing liquid.

The amount of monomer supplied by the spraying operation can be controlled by the type of solvent used for preparing the monomer-containing liquid, the concentration of the monomer-containing liquid, the liquid temperature, the spraying time, the size of the particles to be sprayed, the spraying speed, and the like.
The amount of monomer supplied by the spraying operation varies depending on the type and shape of the sheet-like valve metal substrate, but is preferably in the range of 0.01 to 100 mg / cm ² per unit area of the valve metal substrate. The range of 1-10 mg / cm < ² > is more preferable. If the supply amount is less than 0.01 mg / cm ² , the number of polymerizations must be increased, which is not efficient. On the other hand, when the supply amount exceeds 100 mg / cm ² , the amount of unreacted monomer increases and it becomes difficult to produce a polymer film having high strength.

The average particle size of the fine liquid particles to be sprayed varies depending on the type of solvent, the monomer concentration, the temperature of the monomer-containing liquid, etc., but generally preferably 1 μm or more and less than 1,000 μm, more preferably 10 μm or more and 300 μm. Is less than. When the average particle diameter is less than 1 μm, the adhesion to the valve metal substrate is not efficient. On the contrary, when the average particle diameter is 1,000 μm, the adhesion thickness to the valve metal substrate is not uniform, and it is difficult to form a uniform polymerized film. The average particle diameter of the liquid particles can be controlled by the shape of the spray nozzle, the spray pressure, the spray amount, and the like.

The shape of the spray nozzle can be appropriately selected from a sector nozzle, a full cone nozzle, an empty cone nozzle, a full cone nozzle, a linear nozzle, and a straight nozzle in accordance with the shape of the valve metal substrate. For example, a full cone nozzle is preferable for a circular substrate, and a full pyramid nozzle is preferably used for a rectangular or square substrate. By using a linear nozzle to scan the nozzle or the rectangular substrate left and right, the monomer can be uniformly supplied to the rectangular substrate.

The time for spraying the monomer-containing liquid applied in step 1 is a time that is longer than 15 minutes and preferably less than 15 minutes, and is preferably sufficient to adhere a predetermined amount of the monomer component in the liquid onto the dielectric surface of the valve metal foil substrate. Is 0.1 second to 5 minutes, more preferably 1 second to 30 seconds.
The spraying temperature is preferably −10 to 60 ° C., particularly preferably 0 to 40 ° C. If it is less than -10 degreeC, it takes time for a solvent to volatilize and it is unpreferable from reaction time becoming long. If it exceeds 60 ° C., the volatilization of the solvent and monomer cannot be ignored and the concentration control becomes difficult.

The concentration of the monomer-containing liquid is not particularly limited, and any concentration can be used, but it is preferably 3 to 70% by mass, more preferably 25%, which is excellent in impregnation into fine pores of the valve action metal. Used at ~ 45% by weight.

Examples of the solvent for the monomer-containing liquid used in Step 1 include ethers such as tetrahydrofuran (THF), dioxane, and diethyl ether; ketones such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, benzonitrile, and N-methylpyrrolidone. (NMP), aprotic polar solvents such as dimethyl sulfoxide (DMSO); esters such as ethyl acetate and butyl acetate; non-aromatic chlorinated solvents such as chloroform and methylene chloride; nitro such as nitromethane, nitroethane, and nitrobenzene Compounds; alcohols such as methanol, ethanol, propanol; or water, or a mixed solvent thereof can be used. Preferably, alcohols or ketones or a mixed system thereof is used.

The drying step performed after spraying in step 1 is performed to evaporate the solvent and concentrate the monomer-containing liquid. In step 1, the drying temperature is not particularly limited as long as it is a temperature not higher than the boiling point of the monomer, and a temperature in the range from room temperature to the boiling point of the solvent to be used is preferably used. The drying time can be arbitrarily selected depending on the combination of drying temperature, atmosphere, wind speed, humidity and the like, but more specifically, 1 second to 1 hour is preferable, more preferably 10 seconds to 30 minutes, and particularly preferable. Is 30 seconds to 10 minutes.

The monomer is oxidatively polymerized in the step 2 of spraying and drying of the oxidant-containing liquid, that is, in the step 2 of keeping in the air for a predetermined time in a certain temperature range. A method of proceeding oxidative polymerization by holding in is preferable. The temperature maintained in air varies depending on the type of monomer, but may be, for example, 5 ° C. or less for pyrrole and about 30 to 60 ° C. for thiophene.

The polymerization time depends on the amount of monomer attached during spraying in Step 1. The amount of adhesion varies depending on the concentration and viscosity of the monomer and oxidant-containing liquid, so it cannot be specified unconditionally. However, generally, if the amount of adhesion is reduced, the polymerization time can be shortened, and the amount of adhesion per time is increased. Longer polymerization times are then required. In the method of the present invention, one polymerization time is 10 seconds to 30 minutes, preferably 3 to 15 minutes.

The spraying time of the oxidizing agent applied as the step 2 is a time sufficient for the oxidizing agent component to adhere on the dielectric surface of the metal foil substrate to a time of 15 minutes or more, preferably 0.1 second to 5 minutes, or more. Preferably, it is 1 second to 30 seconds.

The amount of oxidant supplied by the spraying operation is defined by the amount of monomer supplied in step 1. That is, it is preferable to supply 1.1 to 10 times as many oxidizers as the number of moles of monomers supplied in Step 1, and it is more preferable to supply 1.2 to 2.5 times as many oxidizers. Specifically, the oxidizing agent supply amount per unit area of the valve metal substrate is preferably in the range of 0.01 - 100 / cm ^2, the range of 0.1 to 10 mg / cm ² is more preferable. If the supply amount is less than 0.01 mg / cm ² , the number of polymerizations must be increased, which is not efficient. On the contrary, when the supply amount exceeds 100 mg / cm ² , the amount of the unreacted oxidant increases, the gap generated after dissolution and removal increases, and the strength of the polymer film decreases.

The average particle diameter of the fine oxidant-containing liquid particles to be sprayed varies depending on the type of the solvent, the oxidant concentration, the temperature of the oxidant-containing liquid, etc., but is generally preferably 1 μm or more and less than 1,000 μm, more Preferably they are 10 micrometers or more and less than 300 micrometers. When the average particle diameter is less than 1 μm, the adhesion to the valve metal substrate is not efficient. On the contrary, when the average particle diameter is 1,000 μm, the adhesion thickness to the valve metal substrate is not uniform, and it is difficult to form a uniform polymerized film. The average particle diameter of the liquid particles can be controlled by the shape of the spray nozzle, the spray pressure, the spray amount, and the like.

The shape of the spray nozzle can be appropriately selected from a sector nozzle, a full cone nozzle, an empty cone nozzle, a full cone nozzle, a linear nozzle, and a straight nozzle in accordance with the shape of the valve metal substrate. For example, a full cone nozzle is preferable for a circular substrate, and a full pyramid nozzle is preferably used for a rectangular or square substrate. By using a linear nozzle to scan the nozzle or the rectangular substrate left and right, the oxidant can be uniformly supplied to the rectangular substrate.

Examples of the oxidizing agent used in step 2 include an aqueous oxidizing agent and an organic solvent oxidizing agent. Examples of the aqueous oxidizing agent preferably used in the present invention include peroxodisulfuric acid and its Na salt, K salt, NH ₄ salt, cerium (IV) nitrate, cerium (IV) ammonium nitrate, iron (III) sulfate, nitric acid Examples include iron (III) and iron (III) chloride. Examples of organic solvent-based oxidizing agents include ferric salts of organic sulfonic acids such as iron (III) dodecylbenzenesulfonate and iron (III) p-toluenesulfonate. Among these, peroxodisulfate (persulfate) is preferable.

Examples of the solvent for the oxidizing agent-containing liquid used in Step 2 of the present invention include ethers such as tetrahydrofuran (THF), dioxane, and diethyl ether; ketones such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, benzonitrile, N -Aprotic polar solvents such as methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO); alcohols such as methanol, ethanol and propanol; or water; or a mixed solvent thereof can be used. Preferably, water, alcohols or ketones or a mixed system thereof is used.
The concentration of the oxidant-containing liquid is preferably 5 to 50% by mass, and the temperature of the oxidant-containing liquid is preferably −15 to 60 ° C.

In step 2, drying performed after spraying is performed to evaporate the solvent and concentrate the oxidant-containing liquid. The drying temperature performed in step 2 is preferably a temperature ranging from room temperature to the boiling point of the solvent used. The drying time can be arbitrarily selected depending on the combination of drying temperature, atmosphere, wind speed, humidity and the like, but more specifically, 1 second to 1 hour is preferable, more preferably 10 seconds to 30 minutes, and particularly preferable. Is 30 seconds to 10 minutes. Due to the drying performed after the spraying in step 2, the chemical oxidative polymerization of the monomer in contact with the oxidant proceeds to form a solid electrolyte.

Spraying of the monomer-containing liquid in step 1 and spraying of the oxidant-containing liquid in step 2 can be performed on the surface of the valve action metal in a stationary state, but in order to improve spray uniformity, the valve action metal is fixed at a certain angle. Can be sprayed while rotating intermittently or while continuously rotating the valve metal.

In the present invention, the step 3 of dipping in a solution capable of dissolving the oxidizing agent and holding for 0.1 to 120 seconds and then drying is performed after the step 2 on the dielectric surface or the polymer composition through the drying process. This is carried out to remove a part of the oxidant formed in the step. Most of the oxidant deposited on the dielectric surface or polymer composition through the drying process is dissolved and removed by immersing it in a solution capable of dissolving the oxidant (not cleaning). The dissolved oxidant is present in the vicinity of a diffusion layer, but its concentration is low, so that the oxidant layer remaining on the dielectric surface or polymer composition due to reattachment is the stage of step 2. It is significantly reduced compared to On the other hand, the oxidizing agent that has penetrated into the polymer composition is hardly dissolved and removed by the short-time immersion in the step 3. In this way, excess (unreacted) monomer remaining without reacting in the polymerization step can be polymerized in the next step, and as a result, a solid electrolyte composed of a conductive polymer having a laminar structure having a wide range of overlap. Can be formed.

Specifically, the immersion time in step 3 is in the range of 0.1 to 120 seconds, more preferably in the range of 0.1 to 60 seconds, and particularly preferably in the range of 0.1 to 30 seconds.
In the cleaning process after the formation of the solid electrolyte, the oxidant layer is completely dissolved and removed, and a space where the oxidant layer was present forms a polymer film having a layered structure.
The interlayer distance existing between the polymerized films having a layered structure is in the range of 0.01 to 5 μm, more preferably in the range of 0.1 to 2 μm.

Furthermore, it is preferable that the mass of the polymer film after the oxidant is dissolved and removed through the dipping process is 55 to 90%, more preferably 60 to 85% with respect to the mass of the polymer film containing the oxidant.
The space ratio with respect to the volume of the polymerized film after dissolving and removing the oxidizing agent in the present invention is preferably 0.01 to 20%, more preferably 0.1 to 10%, and still more preferably 0.5 to 10%.

As the liquid that can dissolve the oxidizing agent used in Step 3, a solvent that dissolves the oxidizing agent used in Step 2 or a liquid that can dissolve the oxidizing agent can be used. As the liquid that can dissolve the oxidizing agent, a liquid that does not contain an oxidizing agent is usually used. Specific examples of the solvent used include water; alcohols such as methanol, ethanol, and propanol; and aprotic polar solvents such as dimethylformamide, N-methyl-2-pyrrolidinone, and dimethyl sulfoxide. Is water or alcohols, particularly preferably water.

Moreover, a dopant and / or surfactant can be dissolved in water if desired. Examples of the dopant include organic sulfonic acid compounds, organic sulfinic acid compounds, sulfuric acid, carboxylic acids, phosphoric acid, organic phosphoric acid compounds and salts thereof, and halogens. Of these, aliphatic sulfonic acids, aromatic sulfonic acids and salts thereof are preferably used.

Conventionally, when a high concentration oxidant is used, the inlet of the micropores in the valve metal having micropores is blocked by the polymerized film or the oxidant, and the supply of monomer or oxidant to the pores thereafter proceeds. However, the formation of the polymer film in the pores becomes insufficient, resulting in a decrease in the appearance rate of capacity and an increase in leakage current. The method of the present invention is effective in forming a dense polymer film without sealing the inlet in the pores in order to remove unnecessary components of the oxidizing agent that does not function as a polymer film each time it is polymerized. It is.

In Step 2 and / or Step 3, a suspension containing organic fine particles is more preferably used. The organic fine particles are effective for assisting the supply of the oxidant and the monomer to the smooth polymer film surface filled with the polymer film in the pores by remaining on the dielectric surface or the polymer composition. In particular, after forming the solid electrolyte layer by using soluble organic fine particles, the soluble organic fine particles can be dissolved and removed, and the reliability of the capacitor element can be improved.

Solvents used in the process of dissolving and removing organic fine particles include water; alcohols such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; and non- solvents such as dimethylformamide, N-methyl-2-pyrrolidinone and dimethyl sulfoxide. A protic polar solvent is used, but water, alcohols, or a mixed solvent thereof is preferable, and a solvent that also dissolves the oxidizing agent is more preferable because it can be performed simultaneously with the removal of the oxidizing agent.

Soluble inorganic fine particles that can be removed by the use of a strong acid are not preferable because they cause damage such as dissolution or corrosion of the dielectric film on the surface of the valve metal.
The soluble organic fine particles preferably have an average particle diameter (D ₅₀ ) in the range of 0.1 to 20 μm, and more preferably 0.5 to 15 μm. If the average particle diameter (D ₅₀ ) of the soluble organic fine particles exceeds 20 μm, the gap formed in the polymerized film becomes large, which is not preferable. Conversely, if the average particle diameter is less than 0.1 μm, the effect of increasing the adhesion liquid is lost and is equivalent to water. become.

Specific examples of the soluble organic fine particles include aliphatic sulfonic acid compounds, aromatic sulfonic acid compounds, aliphatic carboxylic acid compounds, aromatic carboxylic acid compounds, and salts thereof, and peptide compounds, among others. An aromatic sulfonic acid compound, an aromatic carboxylic acid compound, and a peptide compound are preferably used. These can be used alone or in combination of two or more.

Specific examples of the aromatic sulfonic acid compound include benzene sulfonic acid, toluene sulfonic acid, naphthalene sulfonic acid, anthracene sulfonic acid, anthraquinone sulfonic acid and / or a salt thereof, and specific examples of the aromatic carboxylic acid compound include benzoic acid, Specific examples of toluene carboxylic acid, naphthalene carboxylic acid, anthracene carboxylic acid, anthraquinone carboxylic acid or / and salts thereof, and peptide compounds include surfactin, iturin, prepastatin, and serauchen.

In step 2 and / or step 3, a polymerized film is more uniformly formed by using a surfactant. That is, in the process of concentrating and drying the oxidant-containing liquid, the oxidizer-containing liquid on the aluminum foil surface is inhibited from running out, and the oxidant-containing liquid is prevented from aggregating due to the liquid running out, thereby forming a uniform polymer film. In addition, when the oxidizer dissolved in the solvent is reattached to the aluminum foil surface as an oxidizer solution, the oxidizer solution on the aluminum foil surface is prevented from running out of liquid and preventing the oxidizer solution from aggregating due to the liquid running out. As a result, a uniform polymerized film is formed.

Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, a silicone surfactant, a peptide surfactant, and the like. Those that can be washed and removed after formation are preferably used. Specific examples of the anionic surfactant include alkyl sulfate ester, polyoxyethylene alkyl ether sulfate ester, alkylbenzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl sulfosuccinic acid, alkyl diphenyl ether disulfonic acid, fatty acid, perfluoro fatty acid, naphthalene sulfone. Examples thereof include acid formalin condensates and salts thereof. Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivative, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester , Polyoxyethylene fatty acid ester, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkylamine, alkylalkanolamide and the like. Examples of amphoteric surfactants include alkylbetaines and amine oxides, and examples of peptide surfactants include surfactin, iturin, prepastatin, and seraucheen. Among these specific examples, anionic surfactants are preferably alkylbenzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl sulfosuccinic acid, alkyl diphenyl ether disulfonic acid, fatty acid, perfluoro fatty acid, and nonionic surfactant is preferably polyoxy Ethylene alkyl ether and polyoxyalkylene alkyl ether are preferred.

In the method of the present invention, it is necessary to control the number of sprays in order to make the formed conductive polymer composition have a thickness resistant to humidity, heat, stress and the like.
A preferable first forming method of the solid electrolyte according to the present invention is a method in which the steps 1, 2, and 3 are repeated a plurality of times as one cycle. A desired solid electrolyte layer can be formed by repeating the cycle a plurality of times, preferably 3 times or more, more preferably 8 to 30 times, for one anode substrate. Note that step 1 and step 2 may be performed in reverse order, but step 3 is performed after step 2.

In the second preferred method for forming a solid electrolyte according to the present invention, Step 1, Step 2, and Step 3 are repeated as a cycle (hereinafter abbreviated as cycle A) a plurality of times, and then Step 1 and Step 2 are defined as 1 This is a method of repeating a plurality of times as a cycle (hereinafter abbreviated as cycle B). After repeating the cycle A preferably 3 times or more, more preferably 4 to 10 times for one anode substrate, the cycle B is preferably 3 times or more, more preferably for one anode substrate. By repeating 4 to 30 times, a more desirable solid electrolyte layer can be formed.

According to the present invention, an aluminum foil having a dielectric oxide film is impregnated, for example, in an isopropyl alcohol (IPA) solution of 3,4-ethylenedioxythiophene (EDT), as shown in the following examples. After substantially drying IPA to remove IPA, impregnation with about 20% by mass of an oxidizing agent (ammonium persulfate) aqueous solution, followed by heating at about 40 ° C. for 10 minutes, and by repeating this step, poly (3 , 4-ethylenedioxythiophene) polymer can be obtained.

The conductive polymer forming the solid electrolyte used in the present invention is a polymer of an organic polymer monomer having a π-electron conjugated structure, and the degree of polymerization is 2 or more and 2000 or less, more preferably 3 or more and 1000 or less, and still more preferably 5 It is 200 or less. Specific examples include a conductive polymer containing a structure represented by a compound having a thiophene skeleton, a compound having a polycyclic sulfide skeleton, a compound having a pyrrole skeleton, a compound having a furan skeleton, a compound having an aniline skeleton, or the like as a repeating unit. Is mentioned.

Examples of the monomer having a thiophene skeleton include 3-methylthiophene, 3-ethyloffene, 3-propylthiophene, 3-butylthiophene, 3-pentylthiophene, 3-hexylthiophene, 3-heptylthiophene, 3-octylthiophene, 3-nonylthiophene, 3-decylthiophene, 3-fluorothiophene, 3-chlorothiophene, 3-bromothiophene, 3-cyanothiophene, 3,4-dimethylthiophene, 3,4-diethylthiophene, 3,4-butylenethiophene , Derivatives of 3,4-methylenedioxythiophene, 3,4-ethylenedioxythiophene, and the like. These compounds are generally commercially available compounds or known methods (eg Synthetic
Metals magazine, 1986, Vol. 15, p. 169).

Specific examples of the monomer having a polycyclic sulfide skeleton include compounds having a 1,3-dihydropolycyclic sulfide (also known as 1,3-dihydrobenzo [c] thiophene) skeleton, 1,3-dihydronaphtho [2,3 -C] A compound having a thiophene skeleton can be used. Furthermore, a compound having a 1,3-dihydroanthra [2,3-c] thiophene skeleton and a compound having a 1,3-dihydronaphthaseno [2,3-c] thiophene skeleton can be given. These can be prepared by a known method, for example, the method described in JP-A-8-3156.

A compound having a 1,3-dihydronaphtho [1,2-c] thiophene skeleton is a 1,3-dihydrophenanthra [2,3-c] thiophene derivative or 1,3-dihydrotriphenylo [2]. , 3-c] thiophene skeleton, 1,3-dihydrobenzo [a] anthraceno [7,8-c] thiophene derivatives and the like can also be used.
A compound optionally containing nitrogen or N-oxide in the condensed ring can also be used, such as 1,3-dihydrothieno [3,4-b] quinoxaline, 1,3-dihydrothieno [3,4-b] quinoxaline- 4-oxide, 1,3-dihydrothieno [3,4-b] quinoxaline-4,9-dioxide and the like can be mentioned.

Examples of the monomer having a pyrrole skeleton include 3-methylpyrrole, 3-ethylpyrrole, 3-propylpyrrole, 3-butylpyrrole, 3-pentylpyrrole, 3-hexylpyrrole, 3-heptylpyrrole, 3-octylpyrrole, 3-nonylpyrrole, 3-decylpyrrole, 3-fluoropyrrole, 3-chloropyrrole, 3-bromopyrrole, 3-cyanopyrrole, 3,4-dimethylpyrrole, 3,4-diethylpyrrole, 3,4-butylenepyrrole , Derivatives of 3,4-methylenedioxypyrrole, 3,4-ethylenedioxypyrrole and the like. These compounds can be prepared commercially or by known methods.

Examples of the monomer having a furan skeleton include 3-methylfuran, 3-ethylfuran, 3-propylfuran, 3-butylfuran, 3-pentylfuran, 3-hexylfuran, 3-heptylfuran, 3-octylfuran, 3-nonylfuran, 3-decylfuran, 3-fluorofuran, 3-chlorofuran, 3-bromofuran, 3-cyanofuran, 3,4-dimethylfuran, 3,4-diethylfuran, 3,4-butylenefuran, 3,4 -Derivatives such as methylenedioxyfuran and 3,4-ethylenedioxyfuran can be mentioned. These compounds can be prepared commercially or by known methods.

Examples of the monomer having an aniline skeleton include 2-methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, 2-pentylaniline, 2-hexylaniline, 2-heptylaniline, 2-octylaniline, 2-nonylaniline, 2-decylaniline, 2-fluoroaniline, 2-chloroaniline, 2-bromoaniline, 2-cyanoaniline, 2,5-dimethylaniline, 2,5-diethylaniline, 2,3-butyleneaniline , Derivatives of 2,3-methylenedioxyaniline, 2,3-ethylenedioxyaniline, and the like. These compounds can be prepared commercially or by known methods.

Among these, compounds having a thiophene skeleton or a polycyclic sulfide skeleton are preferable, and 3,4-ethylenedioxythiophene (EDT) and 1,3-dihydroisothianaphthene are particularly preferable.
There is no restriction | limiting in particular in the polymerization conditions etc. of the compound chosen from the said compound group, It can implement easily, after confirming preferable conditions beforehand by simple experiment.

In addition, a compound selected from the above monomer group may be used in combination to form a solid electrolyte as a copolymer. The composition ratio of the polymerizable monomer at that time depends on the polymerization conditions, and the preferred composition ratio and polymerization conditions can be confirmed by a simple test.
For example, a method in which the EDT monomer and the oxidizing agent are preferably applied in the form of a solution and applied separately or together on the oxide film layer of the metal foil can be used (Patent No. 3040113, US Pat. No. 6229689).

3,4-ethylenedioxythiophene (EDT) preferably used in the present invention dissolves well in the above monohydric alcohol, but is not well-suited with water, so when brought into contact with a high concentration aqueous oxidant solution, In the EDT, polymerization proceeds well at the interface, and a conductive polymer solid electrolyte layer having a fibril structure or a lamellar (thin layered) structure is formed.

In the production method of the present invention, as a solvent for washing after formation of the solid electrolyte, for example, ethers such as tetrahydrofuran (THF), dioxane and diethyl ether; ketones such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, benzonitrile, N -Aprotic polar solvents such as methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO); esters such as ethyl acetate and butyl acetate; non-aromatic chlorinated solvents such as chloroform and methylene chloride; nitromethane, nitroethane, and nitrobenzene Nitro compounds such as: alcohols such as methanol, ethanol, and propanol; organic acids such as formic acid, acetic acid, and propionic acid; acid anhydrides of the organic acids (eg, acetic anhydride, etc.) or water or a mixture thereof. Can. Preferably, water, alcohols or ketones or a mixed system thereof is desirable.

The electrical conductivity of the solid electrolyte thus produced is in the range of about 0.1 to about 200 S / cm, preferably about 1 to about 150 S / cm, more preferably about 10 to about 100 S / cm. It is.
On the conductive polymer composition layer thus formed, it is preferable to provide a conductor layer in order to improve electrical contact with the cathode lead terminal. The conductor layer is formed by, for example, a conductive paste, plating, vapor deposition, or sticking of a conductive resin film.

In the present invention, the conductive layer can be compressed after being formed. For example, in the case of a conductor layer including an elastic body, it can be plastically deformed by compression to make it thinner, and also has an effect of smoothing the surface of the conductor layer.
The solid electrolytic capacitor element thus obtained is usually used as a capacitor product for various applications by connecting lead terminals and applying an exterior such as a resin mold, a resin case, a metal exterior case, or a resin dipping.

The present invention will be described in more detail below with typical examples. Note that these are merely illustrative examples, and the present invention is not limited thereto.
Example 1
Masking was made by applying and drying a polyimide solution with a width of 1 mm so that an 80 mm × 75 mm square aluminum conversion foil (thickness 110 μm, 33 V conversion foil) was divided into 5 mm width portions. Next, a 2.0 mol / L isopropyl alcohol (IPA) solution in which 3,4-ethylenedioxythiophene was dissolved was sprayed on one side of the 75 mm × 75 mm portion of the aluminum foil for 2 seconds. The supply amount of 3,4-ethylenedioxythiophene was 0.8 mg / cm ² . The spray surface was dried at room temperature for 5 minutes, and 1.5 mol adjusted so that sodium 2-anthraquinone sulfonate (D ₅₀ = 11 μm; measured using a master sizer manufactured by Sysmex Corporation) was 0.07% by mass. A suspension in which dodecylbenzenesulfonic acid was added to a / L ammonium persulfate aqueous solution so as to be 0.1% by mass and stirred uniformly was sprayed for 2 seconds. Subsequently, the aluminum foil was left in the atmosphere at 40 ° C. for 10 minutes to carry out oxidative polymerization. Subsequently, this foil was impregnated with distilled water for 10 seconds, the aluminum foil was taken out, and left in the atmosphere at 40 ° C. for 10 minutes to carry out oxidative polymerization. The supply amount of the oxidizing agent measured after drying was 1.5 mg / cm ² . Further, the solid electrolyte layer of the conductive polymer was formed on the outer surface of the aluminum foil so that the dipping process and the polymerization process were performed 10 times in total. The finally produced poly (3,4-ethylenedioxythiophene) was washed in 50 ° C. warm water, and then dried at 100 ° C. for 30 minutes to form a solid electrolyte layer.

Using a film thickness meter (manufactured by Peacock: digital dial gauge DG-205, accuracy of 3 μm), the thickness was measured by slowly sandwiching the aluminum foil between the measurement portions of the film thickness meter. When the film thickness of the solid electrolyte layer was measured at nine locations on the aluminum conversion foil on which a solid electrolyte of 75 mm × 75 mm square was formed, the average film thickness was 130 μm and the standard deviation was 3 μm.
Next, a 75 mm × 75 mm portion on which the solid electrolyte layer was formed was immersed in a 15% by mass ammonium adipate solution, and the anode contact was provided on the valve-acting metal foil in the portion where the solid electrolyte layer was not formed. Then, re-chemical conversion was performed.

Next, as shown in FIG. 1, a carbon paste and a silver paste were attached to the portion where the conductive polymer composition layer of the aluminum foil was formed, one aluminum foil was laminated, and a cathode lead terminal was connected. Moreover, the anode lead terminal was connected to the part in which the conductive polymer composition layer was not formed by welding. Further, the device was packaged by resin dipping and then subjected to aging for 2 hours by applying a rated voltage (24 V) at 125 ° C. to complete a capacitor. The capacitance of this capacitor element at 120 Hz was 1414 μF, the leakage current at a rated voltage of 12.5 V was 135 μA, tan δ was 1.8%, and ESR was 17 mΩ, which was sufficiently satisfactory. In addition, when the capacitor element having a leakage current exceeding 0.01 CV was determined to be a defective product among the 10 capacitor elements prepared by using this method, there was no defective product.

Example 2
A 160 mm square aluminum conversion foil (thickness: 110 μm, 33 V conversion foil) was coated with a polyimide solution having a width of 1 mm so as to be divided into portions having a width of 5 mm and dried to form a mask. Next, a 2.0 mol / L isopropyl alcohol (IPA) solution in which 3,4-ethylenedioxythiophene was dissolved was sprayed on one side of the aluminum foil at 155 mm × 160 mm for 2 seconds. The supply amount of 3,4-ethylenedioxythiophene was 1.0 mg / cm ² . The spray surface was dried at room temperature for 5 minutes, and 1.5 mol adjusted so that sodium 2-anthraquinone sulfonate (D ₅₀ = 11 μm; measured using a master sizer manufactured by Sysmex Corporation) was 0.07% by mass. A suspension in which dodecylbenzenesulfonic acid was added to a / L ammonium persulfate aqueous solution so as to be 0.1% by mass and stirred uniformly was sprayed for 2 seconds. Subsequently, the aluminum foil was left in the atmosphere at 40 ° C. for 10 minutes for oxidative polymerization. The supply amount of the oxidizing agent measured after drying was 2.0 mg / cm ² . Subsequently, this foil was impregnated with distilled water for 10 seconds, the aluminum foil was taken out, and left in the atmosphere at 40 ° C. for 10 minutes to carry out oxidative polymerization. Further, the solid electrolyte layer of the conductive polymer was formed on the outer surface of the aluminum foil so that the dipping process and the polymerization process were performed 10 times in total. The finally produced poly (3,4-ethylenedioxythiophene) was washed in 50 ° C. warm water, and then dried at 100 ° C. for 30 minutes to form a solid electrolyte layer.

Using a film thickness meter (manufactured by Peacock: digital dial gauge DG-205, accuracy of 3 μm), the thickness was measured by slowly sandwiching the aluminum foil between the measurement portions of the film thickness meter. When the film thickness of the solid electrolyte layer was measured at 9 locations of the aluminum conversion foil on which the solid electrolyte of 155 mm × 160 mm square was formed, the average film thickness was 130 μm and the standard deviation was 3 μm.
Next, a 155 mm × 160 mm portion where the solid electrolyte layer was formed was immersed in a 15% by mass ammonium adipate solution, and the anode contact was provided on the portion of the valve action metal foil where the solid electrolyte layer was not formed. Then, re-chemical conversion was performed.

Next, as shown in FIG. 1, a carbon paste and a silver paste were attached to the portion where the conductive polymer composition layer of the aluminum foil was formed, one aluminum foil was laminated, and a cathode lead terminal was connected. Moreover, the anode lead terminal was connected to the part in which the conductive polymer composition layer was not formed by welding. Further, the device was packaged by resin dipping and then subjected to aging for 2 hours by applying a rated voltage (24 V) at 125 ° C. to complete a capacitor. The capacitance of this capacitor element at 120 Hz was 5185 μF, the leakage current at a rated voltage of 12.5 V was 445 μA, tan δ was 2.0%, and ESR was 25 mΩ, which was sufficiently satisfactory. In addition, when the capacitor element having a leakage current exceeding 0.01 CV was determined to be a defective product among the 10 capacitor elements prepared by using this method, there was no defective product.

Comparative Example 1
In Example 1, except that Step 3 (oxidative polymerization step of impregnating distilled water for 10 seconds and leaving this aluminum foil in the atmosphere at 40 ° C. for 10 minutes) was not performed, the same as Example 1. Then, when the solid electrolyte layer was formed and the thickness was measured in the same manner at nine locations of the aluminum formed foil, the average film thickness was 204 μm and the standard deviation was 31 μm. In addition, when it was judged that the capacitor element having a leakage current exceeding 0.01 CV was defective for 10 capacitor elements prepared using this method, there were 4 defective products.

Sectional drawing of the example of a solid electrolytic capacitor using a capacitor | condenser element.

Explanation of symbols

1 Anode Base 2 Dielectric (Oxide Film) Layer 3 Masking 4 Semiconductor (Solid Electrolyte) Layer 5 Conductor Layers 6 and 7 Lead Wire 8 Sealing Resin 9 Solid Electrolytic Capacitor

Claims (11)

In a method for producing a solid electrolytic capacitor, in which a solid electrolyte layer containing a conductive polymer composition is provided by polymerizing a monomer with an oxidizing agent on a dielectric film formed on a valve-acting metal surface having fine pores, the valve action A step of spraying a liquid containing a monomer on the dielectric film formed on the surface of the metal and then drying (step 1), a step of spraying a liquid containing an oxidizing agent and then drying (step 2), and A solid characterized in that the solid electrolyte layer is provided by a method of repeating a cycle including a step (step 3) of dipping in a solution capable of dissolving an oxidant, holding for 0.1 to 120 seconds , and then drying (step 3). Manufacturing method of electrolytic capacitor.   The manufacturing method of the solid electrolytic capacitor of Claim 1 which repeats the cycle which consists of a process 1, the process 2 and the process 3 several times, and then repeats the cycle which consists of a process 1 and the process 2 several times. Liquid capable of dissolving the oxidizing agent, method for producing a solid electrolytic capacitor according to claim 1 or 2 which is an aqueous solution of water, or a dopant compound and / or surfactant. The method for producing a solid electrolytic capacitor according to any one of claims 1-3 oxidizing agent is persulfate. Liquid capable of dissolving the oxidizing agent, method for producing a solid electrolytic capacitor according to any one of claims 1 to 4 which is a suspension containing organic fine particles. The method for producing a solid electrolytic capacitor according to claim 5 , wherein an average particle diameter (D ₅₀ ) of the organic fine particles is in a range of 0.1 to 20 μm. Organic fine particles, aliphatic sulfonic acid compounds, aromatic sulfonic acid compounds, aliphatic carboxylic acid compound, aromatic carboxylic acid compounds, their salts, and to claim 6 is at least one selected from the group consisting of peptide compound The manufacturing method of the solid electrolytic capacitor of description. Liquid containing an oxidizing agent further method for producing a solid electrolytic capacitor according to any one of claims 1 to 7 including a surfactant. The method for producing a solid electrolytic capacitor according to any one of claims 1 to 8 , wherein the valve metal having a flat dielectric film layer is rotated and sprayed. The solid electrolytic capacitor produced by the production method according to any one of claims 1-9. The solid electrolytic capacitor having a solid electrolyte layer comprising a conductive polymer composition in the production method according to any one of the flat and is a dielectric according to one surface of a valve metal having a coating layer section 1-8.

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