JPH053138A - Manufacture method of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide the title manufacturing method of solid electrolytic capacitor having the excellent dielectric characteristics and excellent bond properties of dielectric oxide film onto the polyaniline solid electrolyte in high yield. CONSTITUTION:The title solid electrolytic capacitor is manufactured by a method wherein a tantalum oxide film to be a dielectric by anode-oxidizing tantalum is provided on the tantalum and then said film is coated with the mixed solution of polyaniline and an aromatic polyamyl acid to be dried up, next the film is processed with polystyrene sulfonic acid water solution so that said polyaniline may be doped with sulfonic acid ions to be turned into a conductive film and finally, a terminal is provided on the film to manufacture the title solid electrolytic capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a solid electrolytic capacitor using conductive polyaniline as an electrolyte.

[0002]

2. Description of the Related Art Conventionally, solid electrolytic capacitors have been manufactured by providing an electrode layer of manganese dioxide or the like on a metal electrode and a metal oxide film, which is a dielectric layered on the metal electrode, and forming an electrode thereon. There is. Recently, it has been proposed to use a conductive polymer such as polypyrrole or polyaniline obtained by electrolytic oxidation polymerization as an electrolyte of a solid electrolytic capacitor. JP-A-60-244017 and 60-23.
No. 15 and 63-173313. In them, a polymer thin film of pyrrole or aniline is prepared by electrolytic oxidation on a metal electrode having a metal oxide film whose surface is made porous, and used as an electrolyte of a conductive polymer.

[0003]

In order to form a conductive polymer electrolyte on an oxide film, which is an insulator, by electrolytic polymerization by the above method, a thin conductive film is previously formed on the oxide film by chemical polymerization. It was necessary to form layers. Further, there is a problem in industrial mass productivity because it is necessary to polymerize on each capacitor element. From such circumstances, there has been a demand for an industrially advantageous manufacturing method for providing a solid electrolytic capacitor which is simpler and has good quality of a conductive polymer film that can be used as a highly conductive electrolyte. Further, according to the study by the present inventors, it is often seen that the polyaniline film formed on the metal oxide film by the coating method causes delamination, and a capacitor having a low capacity and a high loss can be obtained. was there. Therefore, it is necessary that the oxide film and the solid electrolyte have good adhesiveness. In the case of poor adhesion, problems such as deterioration of product quality and uniformity in production may occur, resulting in reduced production yield and durability during use. There is a problem with sex.
As a result of intensive studies, the present inventors have found that adding a polymer binder to polyaniline improves the adhesion of the polyaniline film formed on the metal oxide film without impairing the performance as a capacitor.

[0004]

According to the present invention, a solid electrolyte layer is formed on a metal oxide film which is a dielectric formed by subjecting the surface of a metal electrode to chemical conversion treatment, and then an electrode is formed thereon. In the method for producing a solid electrolytic capacitor, a mixed film of polyaniline and a polymer binder is formed on the metal oxide film from a solution containing 1 to 25% by weight of a polymer binder with respect to polyaniline, and then the polyaniline is anionic. The present invention provides a method for producing a solid electrolytic capacitor, which comprises forming a layer of a solid electrolyte by adding

As a result of extensive studies on a method for producing a conductive polymer electrolyte membrane of a solid electrolytic capacitor, the present invention uses a mixed solution of a solution of polyaniline dissolved in an organic solvent and a polymer binder to form a dielectric metal. By making a polyaniline film on the oxide film and adding anion, it becomes an excellent electrolyte, and also has good adhesion with the oxide film, and manufactures solid electrolytic capacitors with good characteristics with good yield. It was achieved by finding what was possible.

The present invention will be described in detail below. The metal electrode used in the present invention may be any one capable of forming a dielectric oxide film, and examples thereof include tantalum, aluminum or an aluminum alloy, niobium, and titanium. As a method for forming an oxide film as a dielectric on the surface, a known method such as an anodic oxidation method or an air oxidation method can be used. The anodic oxidation method is preferable for obtaining a porous film having a large surface area. In order to increase the effective surface area before anodizing, known methods such as a method of electrolytically etching a metal surface and a method of sintering metal powder can be used.

As a method for synthesizing the polyaniline used in the present invention, known methods such as a method of oxidative polymerization with an oxidizing agent (hereinafter chemical oxidative polymerization) or a method of electrochemical polymerization with an electrode (hereinafter electrolytic oxidative polymerization) are used. Can be adopted. In chemical oxidative polymerization, polyaniline is synthesized by mixing an acidic solution of aniline with an oxidizing agent.
It is preferable to use an oxidant having an oxidation-reduction potential of 0.6 V or more with respect to the standard hydrogen electrode (NHE) because aniline having excellent polymerization yield and characteristics can be obtained. Below this, aniline will not polymerize. Also, if the potential is too high, the decomposition of aniline occurs, so 2.
A voltage of 5 V or higher is not preferable.

As examples of the oxidizing agent, ferric salts, persulfates, hydrogen peroxide, dichromates and the like can be used. Specifically, as ferric salts, ferric perchlorate, ferric periodate, ferric borofluoride, ferric hexafluorophosphate, ferric sulfate, ferric nitrate, chloride Examples include ferric iron, ammonium persulfate, sodium persulfate and potassium persulfate as the persulfate, and potassium dichromate and sodium dichromate as the dichromate, but are not limited thereto. Not a thing. Among these oxidizers, ferric perchlorate, ferric periodate, ferric borofluoride, ferric hexafluorophosphate, ammonium persulfate, and hydrogen peroxide give good results. preferable. These oxidizing agents may be used alone,
You may use it in mixture of 2 or more types. In order to coat the metal oxide film, polyaniline with excellent solubility is required,
The amount of the oxidizing agent used is preferably 0.1 times to 5 times, more preferably 0.1 times to 2 times, the molar number of aniline.
0.5 times to 2 times is particularly preferable. The anions of these oxidizing agents other than hydrogen peroxide or the anions formed after the oxidation reaction are incorporated into the polyaniline, but are not particularly limited because they are excluded when dissolved.

To synthesize polyaniline by electrolytic oxidation polymerization, aniline may be electrolytically polymerized in the presence of a stable acid under electrolysis conditions. Various methods can be used as a method for electrolytic oxidative polymerization using an acidic aqueous solution of aniline. Specifically, constant current method, constant potential method, constant voltage method, potential scanning method,
Although a potential step method can be mentioned, a constant current method and a constant potential method are preferable in order to control the amount of electricity supplied. Current density in electrolytic oxidative polymerization is aniline concentration, acid concentration,
Although it varies depending on the polymerization temperature, usually 0.001 to 500
It is in the range of mA / cm ² . Particularly, 0.01 to 50 mA
/ Cm ² is preferable, and more preferably 0.1 to 20 mA.
A range of / cm ² is particularly preferred. In the constant potential method and the constant voltage method, the conditions may be selected so that the current density falls within the above range.
For example, in the case of the constant potential method, 0.8 to 10 V is preferable, and 0.8 to 2.0 V is particularly preferable, with respect to the Ag / AgCl electrode.

In both of the above methods, the acid used for polymerization is stable as long as it is stable under the chemical oxidative polymerization or electrolytic oxidative polymerization of aniline, forms a salt with aniline and dissolves aniline in an aqueous solution. Any acid may be used. Specific examples thereof include perchloric acid, fluoroboric acid, hexafluorophosphoric acid, periodic acid, sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid and methanesulfonic acid. Hydrogenic acid, hexafluorophosphoric acid, and periodic acid are preferable because they give good results. The concentration of these acids may be equal to or more than the equivalent of the aniline used, and is usually 0.1 N or more.

The concentration of aniline used in the reaction is not particularly limited. The upper limit is usually a concentration that dissolves in an acidic solution,
Since aniline is oxidized and precipitated as polyaniline by the reaction, there is no particular problem because the aniline is dissolved during the reaction and reacts even if it is used in a concentration higher than the dissolution concentration. The lower limit is also not particularly limited, but it is usually used at 0.1 mol / liter or more because it is not efficient at a too low concentration. The purity of aniline used is not particularly limited, but 95% or more is preferable. For the reaction, an acidic solution containing aniline or a solution containing a slurry of aniline salt may be stirred as it is in the oxidative chemical polymerization, or a solution containing the oxidant may be added and stirred, while in electrolytic oxidative polymerization, the above solution may be stirred. May be placed in an electrolytic cell having an electrode and electrolyzed. Reaction temperature,
The reaction time is not particularly limited, but it is usually carried out at a temperature not lower than the freezing point and not higher than the boiling point of the solution containing aniline, but 50 ° C. or lower, more preferably 4 ° C. or lower to obtain highly soluble polyaniline.
It is better to react at 0 ° C or lower. The reaction time is not particularly limited and can be appropriately determined in consideration of the oxidizing agent used and the amount of energizing current, but it is generally in the range of 5 minutes to 100 hours, and more preferably in the range of 10 minutes to 50 hours. is there.

Of these synthetic methods, chemical oxidative polymerization is preferable because polyaniline having excellent solubility can be easily obtained. The polyaniline obtained by polymerization incorporates anions derived from the oxidizing agent or acid used in the reaction, and it is preferable to remove the anions before dissolution in order to increase the solubility. As a method for removing anions, an alkaline compound that does not react with the polyaniline skeleton may be contacted. The alkali used is not particularly limited as long as the pH of the solution becomes 11 or more after the polyaniline obtained by the polymerization is added, but it is not particularly limited, but sodium hydroxide, potassium hydroxide, lithium hydroxide, aqueous ammonia is used. , Hydrazine, and alkylamines. The polyaniline thus obtained is generally said to have, on average, the following repeating units as the main structure.

[0013]

[Chemical 1] (0 ≦ m ≦ 1, 0 ≦ n ≦ 1, m + n = 1)

The solvent for dissolving polyaniline is not particularly limited as long as it can sufficiently dissolve polyaniline. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. However, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone, which have high solubility, are preferable. When the polyaniline is not completely dissolved at the time of dissolution and there is an insoluble matter, it is preferable to separate it, but it is not always necessary to separate it. At this time, the concentration of the dissolved polyaniline may be within a range such that the polyaniline film has a sufficient viscosity to maintain its shape during the formation of the polyaniline film. To 20% by weight, preferably 0.5 to 15% by weight, more preferably
It is 1 to 10% by weight.

In the present invention, the polymer binder is soluble in a solvent used for polyaniline, has an affinity with an oxide film, is well mixed with polyaniline, and does not undergo phase separation extremely when formed into a layer, and has a relatively affinity. Means a polymer substance having The polymer substance is not particularly limited as long as it has the above properties, and examples thereof include known aromatic polyamic acid (hereinafter abbreviated as polyamic acid), soluble aromatic polyimide (hereinafter soluble). Abbreviated as polyimide), polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and polymers of vinyl compounds. Specifically, as the polyamic acid,

[0016]

[Chemical 2] (Ar represents a tetravalent aromatic group or an Ar ′ divalent aromatic group.)
r is represented by the following chemical formula 3.

[0017]

[Chemical 3] And the like, a tetravalent aromatic group such as Ar ′ is represented by the following chemical formula 4.

[0018]

[Chemical 4] And divalent aromatic groups such as

[0019]

[Chemical 5] (Ar means the same as the above, and Ar ″ represents a divalent aromatic group having a heterocycle.), Which is a polyimide having a repeating unit represented by the following Chemical Formula 6 Ru

[0020]

[Chemical 6] And a divalent aromatic group having a heterocycle. Ar, Ar ′, and Ar ″ may have a substituent on the aromatic ring. The polyamic acid and the soluble polyimide are not particularly limited in polymerization degree, but are usually 10 to 100.
00, preferably 20-1000. Examples of the vinyl compound polymer include acrylic resins such as polymethyl methacrylate and polymethyl acrylate. Among these polymer binders, a molecular weight of 300 to 10,0 which gives good adhesiveness
No. 00 polyethylene glycol, polyamic acid or soluble polyimide is preferable, and polyethylene glycol or polyamic acid is more preferable.
If the amount of the polymer binder is too small, there is not a sufficient effect for improving the adhesiveness, and if it is too large, the dielectric properties of the obtained electrolytic capacitor are adversely affected, which is not preferable. 1 for polyaniline, depending on the type of polymer binder
˜25 wt% may be mixed, more preferably 2 to 15
%, More preferably 3 to 10% by weight.

The method for forming a film of a mixture of polyaniline and the above-mentioned polymer binder (hereinafter sometimes abbreviated as polyaniline film) on the metal oxide film from the obtained solution is not particularly limited, but polyaniline is used. In addition to the method of coating a mixed solution of a polymer binder with a metal oxide film on the metal oxide film, a casting method, a dipping method, or the like is used.
By performing these methods once or twice or more, a polyaniline film having a sufficient thickness can be obtained. Then, the solvent is removed and the film is dried to form a film. As the method, a known method can be adopted. For example, a method of heating and drying under an inert atmosphere and a method of heating and drying under reduced pressure are common. When a solvent having a high boiling point is used, the solvent may be replaced with a solvent having a low boiling point such as water, methanol or acetone and then dried by heating.
If the film thickness of the polyaniline thus prepared is too thick, it becomes difficult to add anions to the inside of the film, and if it is too thin, the strength is insufficient. The range of 100 μm is more preferable.

An example of a method of adding anions to the obtained polyaniline film, that is, a method of doping anions, is a method of immersing the polyaniline film in a solution of an acid containing the anion to be added and reacting it. in this case,
The anion does not have to be the same as at the time of polymerization,
It may be exchanged for another anion. The acid used does not easily corrode the metal oxide film and gives sufficient conductivity to the polyaniline film, and a protic acid having a pKa of 4 or less is preferable. Specifically, perchloric acid, borofluoric acid, sulfuric acid,
Nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, polystyrenesulfonic acid, polyvinylsulfonic acid, etc. are exemplified, but sulfuric acid, p
-Toluenesulfonic acid, methanesulfonic acid, polystyrenesulfonic acid are preferred because they give good results. Anions can be added to polyaniline by immersing the metal with the polyaniline film in these solutions. The temperature and time at this time are not particularly limited, but usually 1 minute or more, 1
00 hours or less, preferably 5 minutes or more and 24 hours or less, the temperature is above the temperature at which the solution used does not solidify,
It is below the boiling point of the solution. For example, 0 ℃ to 1 for water
It is 00 ° C. It is preferable to remove excess acid after the acid treatment because it does not corrode the metal electrode.

When a polyaniline film is prepared from polyaniline which has been deionized with a reducing alkali compound such as hydrazine, it is preferable to carry out oxidation in addition to addition of anions because high conductivity can be obtained. The oxidation method is not particularly limited, but examples thereof include a chemical oxidation method and an electrolytic oxidation method. Specific examples include oxidation with ferric salts, persulfates, hydrogen peroxide, dichromates and the like, electrolytic oxidation at oxidation potential or higher, and oxidation with air. Of these methods, the method using an oxidizing agent is practical and preferable. As the oxidizing agent, ferric perchlorate, ferric borofluoride, ferric nitrate, ferric sulfate, ammonium persulfate and potassium persulfate are preferable. The oxidation can be performed at any time after the film formation, but it is preferable to perform the oxidation before or at the same time as the addition of an anion to the polyaniline in order to obtain a sufficient conductivity.

The polyaniline film thus obtained exhibits an electric conductivity of 10 ^-2 to 10 ² S / cm and exhibits excellent characteristics as an electrolyte of a solid electrolytic capacitor. A terminal is formed on this polyaniline film with a commonly used conductive paste such as carbon paste or silver paste to form an electrode (counter electrode). Further, according to a conventional method, a capacitor is obtained by sealing with a polymer sealing material such as epoxy resin or enclosing it in a metal container.

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

Reference Example 1 (Polymerization of aniline) 0.015 mol of aniline was used as a 1N aqueous solution of perchloric acid 3
It was dissolved in 0 ml. A solution prepared by dissolving 0.015 mol of ammonium persulfate in 20 ml of a 1N aqueous solution of perchloric acid was slowly added dropwise thereto, and the mixture was allowed to react with ice for 1 hour.
The precipitate formed was filtered and washed with water. The precipitate was added to a 1N aqueous sodium hydroxide solution to remove anions. After the treatment, it was thoroughly washed with water and methanol. The treated polyaniline was placed in a vacuum dryer and placed at 60 ° C for 6 hours.
After vacuum drying for a period of time, powdery polyaniline was obtained. Of the powdery polyaniline obtained, 0.08 g was replaced with 3.92 g of N 2.
-Dissolved in methyl-2-pyrrolidone. At that time, 9
8.5% or more was dissolved.

Example 1 0.005 mol of p-phenylenediamine and 0.005 mol of 4,4'-biphthalic dianhydride were dissolved in N-methyl-2-pyrrolidone (NMP) to give a solution of 20.00 g. .. This solution was stirred at 0 ° C. for 8 hours in a nitrogen atmosphere and reacted to obtain an NMP solution of polyamic acid. Next, this polyamic acid solution was mixed with the solution of polyaniline obtained in Reference Example 1 so that the polyamic acid content was 5% by weight with respect to polyaniline.

A polyaniline / polyamic acid mixed film obtained was formed on a dielectric oxide film having a thickness of 0.12 μm formed by performing a chemical conversion treatment using an aqueous solution of ammonium borate as an electrolytic bath using an aluminum plate having a thickness of 250 μm. Part (area 0.123 cm ² ) was treated with a 1N aqueous sulfuric acid solution for 3 minutes to perform acid treatment. After washing with water and vacuum drying,
The terminals were taken with a bomb paste to create a capacitor. The characteristics of this electrolytic capacitor were measured with an LCR meter (Yokogawa Hewlett Packard 4274A).
At 120 Hz, the capacitance is 65 nF / cm ² , tan δ is 5.1%, and at 1 kHz, the capacitance is 62 nF / cm.
² , tan δ was 3.2%. The adhesion between the oxide film and the polyaniline film was good, and the peeling with a cellophane adhesive tape was examined, but almost no peeling was observed even after the acid treatment.

Example 2 As in Example 1, a dielectric oxide film of 0.12 μm was formed.
On a 250 μm thick aluminum plate
A realic acid film is formed, and a part (area 0.144 cm
² ) Is treated with 1N polystyrene sulfonic acid aqueous solution for 3 minutes.
I understood After washing with water, dry under reduced pressure, and then use carbon paste for terminals.
Then, a capacitor was created. Of this electrolytic capacitor
When the characteristics were measured, the electrostatic capacity was 71 n at 120 Hz.
F / cm² , Tan δ is 3.6% and static at 1 kHz
Capacitance is 66 nF / cm ² , Tan δ is 7.5%
It was It should be noted that the polyaniline-polyamic acid film should be coated with cellophane.
The adhesive tape was attached and then peeled off, but no peeling of the film was observed.
I couldn't.

Example 3 A tantalum plate (2 cm) having a thickness of 50 μm and a purity of 99.99%
× 5 cm) according to a conventional anodic oxidation method, using a 1 vol% phosphoric acid aqueous solution as an electrolytic bath, and 100 V at 3 mA / cm ² .
Constant current chemical conversion treatment, and then constant voltage chemical conversion treatment for 60 minutes to form an oxide film having a thickness of 0.12 μm. The polyaniline solution was cast on the tantalum plate having this oxide film, and vacuum dried at 60 ° C. for 6 hours. In the polyaniline solution obtained in Reference Example 1, polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 2000) was added to the polyaniline at 5%.
After mixing by weight%, a part (area: 0.172 cm ² ) of the polyaniline film formed on the oxide film of the tantalum plate was treated with a 1N polystyrenesulfonic acid aqueous solution for 5 minutes to add polystyrenesulfonate ion, It was washed with water and dried under reduced pressure. By this treatment, the doped portion of the polyaniline film turned black green and became a conductor having an electric conductivity of 1.1 × 10 ^-1 S / cm, but the undoped portion was 10 ^-9 S / cm.
It remained the following insulator. Next, a terminal was formed on the doped portion of the polyaniline film with carbon paste to form a capacitor. When the characteristic of this electrolytic capacitor was measured, the electrostatic capacity was 162 nF at 120 Hz.
/ Cm ² and tan δ were 1.4%, the electrostatic capacity was 162 nF / cm ² and tan δ was 1.3% at 1 kHz. The adhesion between the oxide film and the polyaniline film was good, and the peeling by the cellophane adhesive tape was examined in the same manner as in Example 1, but the polyethylene glycol mixture thin film showed almost no peeling even after the acid treatment.

Example 4 Using the solution prepared by mixing the polyaniline solution obtained in Reference Example 1 and the polyamic acid solution obtained in Example 1, a polyaniline-polyamic acid mixture was formed on the oxide film of the tantalum plate in the same manner as in Example 3. A film was formed. The mixing ratio of polyamic acid was 5% by weight with respect to polyaniline. This film 1
After treatment with a specified polystyrene sulfonic acid aqueous solution for 5 minutes to add polystyrene sulfonate ion, the product was washed with water and dried under reduced pressure. Next, a terminal was formed on the doped portion of the polyaniline film with carbon paste to form a capacitor. When the characteristics of this electrolytic capacitor were measured, the electrostatic capacity was 159 nF / cm ² , ta at 120 Hz.
nδ is 6.5% and the electrostatic capacity is 153n at 1 kHz.
F / cm ² and tan δ were 2.9%. Adhesion between the oxide film and the polyaniline film was good, and peeling due to the cellophane adhesive tape was not seen as in Example 1.

Example 5 Using a 200 μm thick titanium plate, a 0.17 μm thick dielectric oxide film formed by chemical conversion treatment of an ethylene glycol solution of ammonium borate as an electrolytic bath at 75 V was carried out in Reference Example 1. The obtained polyaniline solution and polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 2000) were mixed in an amount of 5% by weight with respect to polyaniline to form a polyaniline-polyethylene glycol mixed film. A portion of this was treated with a 1N polystyrene sulfonic acid aqueous solution for 5 minutes to add polystyrene sulfonate ions, washed with water, and depressurized. Next, use carbon paste for polyaniline-
A terminal was formed on the polyethylene glycol film to prepare a capacitor. When the characteristics of this electrolytic capacitor were measured, the electrostatic capacity was 289 nF / cm ² , t at 120 Hz.
anδ is 3.3%, and the capacitance is 292 at 1 kHz.
The nF / cm ² and tan δ were 21%. Adhesion between the oxide film and the polyaniline film was good, and peeling due to the cellophane adhesive tape was not seen as in Example 1.

Example 6 In the same manner as in Example 5, polyaniline-polyamic acid was prepared by using a solution prepared by mixing the polyaniline solution obtained in Reference Example 1 and the polyamic acid solution obtained in Example 1 on the oxide film of a titanium plate. A mixed film was formed. The mixing ratio of polyamic acid was 5% by weight with respect to polyaniline. This membrane was treated with a 1N polystyrene sulfonic acid aqueous solution for 5 minutes to add polystyrene sulfonate ions, and then washed with water,
It was dried under reduced pressure. Next, a terminal was formed on the doped portion of the polyaniline film with carbon paste to form a capacitor. When the characteristics of this electrolytic capacitor were measured, the electrostatic capacity at 120 Hz was 267 nF / cm ² , ta
nδ is 24% and the capacitance is 250 nF at 1 kHz
/ Cm ² and tan δ were 6.7%. Adhesion between the titanium oxide film and the polyaniline film was good, and Example 1
No peeling due to cellophane adhesive tape was observed as in the above.

Comparative Example 1 A polyaniline film was formed in the same manner as in Example 1 by using the polyaniline solution obtained in Reference Example 1 on an aluminum plate having a dielectric oxide film with a thickness of 0.12 μm obtained in Example 1. Then, a part (area 0.144 cm 2) was treated with a 1N sulfuric acid aqueous solution for 3 minutes. A part of the polyaniline film was peeled off. A terminal was formed on the polyaniline with a carbon paste in a portion which was not peeled off to prepare a capacitor. When the characteristics of this electrolytic capacitor were measured, the electrostatic capacity was 71 nF / cm ² , tan δ was 8.8% at 120 Hz, and it was 1 kHz.
z has a capacitance of 66 nF / cm ² and tan δ of 7.1%
Met. The adhesion between the titanium oxide film and the polyaniline film was not good, and peeling occurred due to the cellophane adhesive tape.

Comparative Example 2 The polyaniline solution obtained in Reference Example 1 was cast on the tantalum plate having an oxide film obtained in Example 3 and vacuum dried at 60 ° C. for 6 hours. Part of the obtained polyaniline film (area: 0.
127 cm ² ) was treated with a 1N sulfuric acid aqueous solution for 5 minutes to add sulfate ions, washed with water, and dried under reduced pressure. By this treatment, the doped portion of the polyaniline film turned black green and became a conductor having an electric conductivity of 1.1 × 10 ^-1 S / cm, but the undoped portion was made of an insulator of 10 ^-9 S / cm or less. It remained. Next, a terminal was formed on the doped portion of the polyaniline film with carbon paste to form a capacitor. When the characteristics of this electrolytic capacitor were measured, the electrostatic capacity at 120 Hz was 142 nF / cm ² , ta
nδ is 3.4% and the capacitance is 137n at 1 kHz.
F / cm ² and tan δ were 2.9%. The adhesion between the oxide film and the polyaniline film was examined by peeling with a cellophane adhesive tape, but peeling was observed in some places.

Comparative Example 3 The polyaniline solution obtained in Reference Example 1 was cast on the tantalum plate having a 0.12 μm thick oxide film obtained in Example 3,
It was vacuum dried at 60 ° C. for 6 hours. This membrane was treated with a 1N polystyrene sulfonic acid aqueous solution for 5 minutes to add polystyrene sulfonate ions, then washed with water and dried under reduced pressure.
In the process, part of the polyaniline film was peeled from the oxide film. A terminal was formed on the polyaniline film portion which was not peeled off with the carbon paste, and a capacitor was prepared. When the characteristics of this electrolytic capacitor were measured, 12
The capacitance is 125 nF / cm ² and tan δ is 5.2% at 0 Hz, and the capacitance is 121 nF / c at 1 kHz.
m ² and tan δ were 2.9%. The adhesion between the oxide film and the polyaniline film was examined by peeling with a cellophane adhesive tape, but peeling was observed in some places.

Comparative Example 4 A mixed film of polyaniline and polyamic acid was formed on an oxide film of a tantalum plate in the same manner as in Example 4 except that the mixing ratio of polyamic acid to polyaniline was 30% by weight. This membrane was treated with a 1N polystyrene sulfonic acid aqueous solution for 5 minutes to add polystyrene sulfonate ions, then washed with water and dried under reduced pressure. Next, a terminal was formed on the doped portion of the polyaniline film with carbon paste to form a capacitor. When the characteristic of this electrolytic capacitor was measured, the electrostatic capacity was 179 nF at 120 Hz.
/ Cm ² , tan δ is 36.9%, the electrostatic capacitance is 40 nF / cm ² , tan δ is 147% at 1 kHz, and t
The an δ was very poor. The adhesion between the oxide film and the polyaniline film was good.

Comparative Example 5 As in Example 6, a reference example was formed on the oxide film of the titanium plate.
The polyaniline solution obtained in 1 and the polyamiline obtained in Example 1
The citric acid solutions were mixed to form a mixed film thereof. Polia
Mixing ratio of Mic acid is 30% by weight with respect to polyaniline
Met. This membrane is a 1N polystyrene sulfonic acid aqueous solution
Treat with liquid for 5 minutes and add polystyrene sulfonate ion
After adding, it was washed with water and dried at room temperature for 72 hours. Then
Doped part of polyaniline film with carbon paste
The terminal was formed on the top and the capacitor was created. This electrolytic
When the characteristics of the capacitor are measured, the capacitance at 120Hz
The amount is 237nF / cm² , Tan δ is 61%, 1
Capacitance of 39 nF / cm at kHz ² , Tan δ is 17
It was 5%, and tan δ was very poor. In addition,
The adhesion between the aluminum oxide film and the polyaniline film is good.
It was

[0038]

According to the present invention, a solid electrolytic capacitor having good dielectric properties and good adhesion between a dielectric oxide film and a polyaniline solid electrolyte can be produced simply and with high yield, and is industrially extremely useful. It is useful.

Claims (1)

Claim: What is claimed is: 1. A solid electrolyte layer is formed on a metal oxide film, which is a dielectric formed by subjecting the surface of a metal electrode to chemical conversion treatment, and then an electrode is formed on the solid electrolyte layer. In a method of manufacturing a capacitor, a mixed film of polyaniline and a polymer binder is formed on a metal oxide film from a solution containing 1 to 25% by weight of a polymer binder with respect to polyaniline, and then an anion is added to the polyaniline. A method of manufacturing a solid electrolytic capacitor, which comprises forming a layer of a solid electrolyte by