JPH1187182A - Organic solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture an organic solid electrolytic capacitor with a device that does not require any complex control, by thermocompressing a rough-surface metal foil and a conductive macromolecular film. SOLUTION: A fine hole is formed at a metal film 2 with a valve operation by etching and an oxide covering 3 is formed. Further, drying is made after washing using, for example, an organic solvent. Then, a cathode where a carbon paste 4 is applied to both surfaces of a cathode component metal 5 of, for example, a copper foil is held by a conductive macromolecular film 1, and the side of the oxide covering film 3 of the metal film 2 with a valve operation that becomes an anode is overlapped to the outside for heating and contact bonding under heating/pressurization conditions. In this case, heat bonding is made by applying a pressure of 300 kg/cm<2> or higher while heating to a temperature that is equal to or more than the softening point of a conductive macromolecular film and equal to or less than a decomposition point. Also, an organic acid is doped to the macromolecular film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor having a small size, a large capacitance and a low equivalent series resistance (ESR), and more particularly to an organic solid electrolytic capacitor using a conductive polymer film as a solid electrolyte. It relates to the manufacturing method.

[0002]

2. Description of the Related Art A high-speed processor currently used in personal computers and the like consumes a large amount of power when driven. In particular, a portable device such as a notebook personal computer has a limited power supply, and low power consumption technologies are actively employed. Has been practiced. by the way,
When such low power consumption measures are taken for a portable electronic device such as a personal computer, a mobile phone, a VTR, a digital camera, etc., unnecessary circuits are disconnected each time, or a processor or the like is put into a halt state when unnecessary. That happens frequently. For this reason, a large load change frequently occurs when viewed from the power supply side, and the necessity of a decoupling capacitor having excellent noise absorption performance as a power supply for responding to such a load change is rapidly increasing. I have.

A condition of a capacitor having good noise absorption is that it has a low ESR (equivalent series resistance). As such a low ESR capacitor, there is firstly a multilayer ceramic capacitor, and its capacitance has been increasing in recent years. However, the capacitance is still limited to about 20 μF.

An electrolytic capacitor using aluminum, tantalum, or the like is known as a capacitor capable of providing a large capacity. This electrolytic capacitor is used in combination with a metal having a valve action in order to utilize a function of repairing an electric short circuit due to a defect in a dielectric film.
That is, aluminum, tantalum, niobium and the like.
Further, these electrolytic capacitors have predetermined frequency characteristics, and the resistance (impedance) tends to increase particularly on the high frequency side. This is because the ion-conductive electrolytic solution is used, so that the ions cannot follow up in the high-frequency region and the resistance value increases. As means for improving such frequency characteristics, manganese dioxide, T
Although CNQ (tetracyanoquinodimethane) complex salt and the like are used, there are problems such as insufficient conductivity and insufficient thermal stability.

Further, in recent years, a solid electrolytic capacitor using a conductive polymer instead of an electrolytic solution has been developed. Since the conductive polymer is electronically conductive, there is no frequency dependency restricted by the movement of ions, which are relatively large particles, and the frequency characteristics are significantly improved.

A conventional solid electrolytic capacitor is obtained by electrolytically etching a metal foil having a valve action, such as aluminum, tantalum, or niobium, to make it porous, and then electrolytically oxidize the surface thereof to form a dielectric film. A monomer such as pyrrole is electrolytically or chemically polymerized on a porous pellet obtained by oxidizing the surface of a porous pellet made by sintering fine metal particles, or is immersed in a prepolymerized polymer solution. Thus, a conductive polymer is formed.

In a solid electrolytic capacitor, it is necessary to form a conductive polymer layer in a very small space. For this reason, various studies have been made on film formation by an electrolytic polymerization method from an early stage. However, the dielectric is an insulator, and it is difficult to use it as it is in the electrolytic method. For this reason, for example,
As described in JP-A-74853, a technique of first forming a conductive film by chemical polymerization and then performing electrolytic polymerization is being studied. In addition, a method of starting electrolytic polymerization in a resin state using a needle-like electrode such as gold, and then adjusting the conditions to form a uniform film is also being studied. However, these methods are extremely complicated in manufacturing method, such as performing chemical polymerization in advance or using a needle-like electrode.

Further, as described in Japanese Patent Publication No. 6-50710, electrolytic polymerization is carried out starting from a metal surface of a dielectric where metal is partially exposed to form a conductive polymer film. A method of oxidizing and repairing a dielectric has also been proposed. However, in this method, the conditions for re-formation of the dielectric are difficult, the formation is insufficient, the leakage current increases, and the conductive polymer, which is subjected to severe oxidizing conditions, is oxidized, so that reliability cannot be obtained. There were many. As a method for forming a conductive polymer layer only by chemical polymerization, for example, as described in JP-A-6-310380, a monomer or a monomer solution is impregnated at a low temperature of -70 ° C, and then slowly heated. Has been put to practical use. According to this method, the permeation of the monomer into the porous portion is good, and the polymerization is sufficiently performed. Therefore, a highly conductive polymer is obtained, and excellent characteristics are obtained. However, production at low temperature has many problems such as hygroscopicity and energy cost.

On the other hand, for example, Japanese Patent Application Laid-Open Nos. 62-29124, 5-152168, and 6-45
As described in, for example, Japanese Patent Publication No. 196, a conductive polymer soluble in an organic solvent has also been developed, and attempts have been made to produce the polymer by immersion or coating. In particular, soluble polyaniline is preferably used. However, N-methyl-2-pyrrolidone is often used as the solvent, and satisfactory results in terms of viscosity and drying rate have not been obtained. Further, when doping is performed after the formation of the polymer, there is no assurance that the microporous portion is uniformly doped, and there is a problem that a sufficiently low resistance value cannot be obtained due to variations in characteristics or insufficient doping.

Very few examples have been pre-impregnated with dopants. For example, synthetic metals 69 (1
995) As described in 245-246, only an example in which dodecylbenzenesulfonic acid was used as a dopant and became soluble in xylene was reported.

In addition, for example, as described in JP-A-6-45198, in a winding method using a spacer when an electrolytic capacitor or the like has a large capacity, a wasteful spacer is used as a capacitor to separate electrodes. Attempts to combine functions are also known. That is, a method of using a conductive polymer film as a spacer, impregnating with a monomer after winding, and polymerizing the spacer has been proposed. However, in this method, the conductive polymer film performs the spacer function, but at the interface with the dielectric, the required conductive polymer film is formed from a monomer or polymer solution, and the monomer or high polymer is used. Since a liquid or solution of a molecular solution is used, the complexity of the process is not eliminated.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic solid electrolytic capacitor which can be easily manufactured by using an apparatus which does not require complicated control without using a liquid or a solution, and a method of manufacturing the same. It is.

[0013]

That is, the above object is achieved by the following constitutions. (1) It has a roughened metal foil having a dielectric oxide film on its surface, and a conductive polymer film that is contacted and integrated with the roughened metal foil. An organic solid electrolytic capacitor having a negative electrode, wherein the roughened metal foil and a conductive polymer film are thermocompression bonded. (2) The organic solid electrolytic capacitor according to the above (1), wherein the conductive polymer film is an organic solvent-soluble conductive polymer using an organic acid as a dopant. (3) The organic solid electrolytic capacitor according to the above (2), wherein the soluble conductive polymer is a substituted or unsubstituted polyaniline, polypyrrole or polythiophene. (4) An organic solid electrolytic capacitor in which a conductive polymer film is thermocompression-bonded to a roughened metal foil having a dielectric oxide film on the surface, and a negative electrode is formed on another surface of the conductive polymer layer. Production method. (5) a conductive polymer film on the roughened metal foil;
(4) The method for producing an organic solid electrolytic capacitor according to the above (4), wherein the conductive polymer film is thermocompressed at a temperature not lower than the softening point and not higher than the decomposition point and at a pressure of 300 kg / cm ² or more.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The organic solid electrolytic capacitor of the present invention has a roughened metal foil having a dielectric oxide film on the surface, and a conductive polymer film in contact with the roughened metal foil.
An organic solid electrolytic capacitor having a negative electrode on another surface of the conductive polymer film, wherein the roughened metal foil and the conductive polymer film are thermocompression-bonded.

Since conductive polymers are generally insoluble in organic solvents, it has been considered difficult to obtain a film by a method other than the electrolytic polymerization method. Therefore, a conductive polymer film is formed by electrolytic polymerization on the surface of a plate-like electrode having a certain area, such as platinum, and is peeled off, washed and dried, and used in the following steps. In this case, the monomers used for the polymerization preferably include pyrrole, aniline, thiophene, furan and the like, and derivatives thereof.

Although there are restrictions on the soluble dopant, alkylbenzene sulfonic acids such as p-toluenesulfonic acid, or salts thereof, and phosphoric acid are preferably used. Further, naphthalene or the like may be polymerized in a suspended state.

As a method for producing the conductive polymer film, a casting method from an organic solvent solution can be preferably mentioned. In this case, so as to be soluble in the organic solvent,
It is necessary to devise a monomer or a polymerization method. That is, it is necessary to introduce a substituent such as an alkyl group into the monomer, or to carry out polymerization so that the morphology after polymerization is effective for solubility. As such an example, for example, a thiophene or pyrrole polymer substituted with a butyl group, a hexyl group, an octyl group, a dodecyl group, or the like, and a copolymer thereof can be preferably exemplified. More preferably, a film formed by dissolving polyaniline or the like synthesized by a chemical polymerization method in a solvent, casting and molding the same, and the like can be given.

The introduction of the dopant may be carried out by immersing the film in a solution of the dopant or by casting a liquid in which the dopant and a monomer such as polyaniline are dissolved in advance. It is preferable because it is easily obtained. For example, polyaniline as a preferred monomer is known to have three different oxidation states, of which emeraldine polyaniline has the highest conductivity, while luco emeraldine and pergranine polyaniline have relatively low conductivity. Therefore, it is preferable to synthesize emeraldine polyaniline. Such a method for synthesizing a soluble polymer having high conductivity (polyaniline) is as follows.
Known methods such as a method of synthesizing using an oxidizing agent (chemical polymerization) can be employed. By using an oxidizing agent having an oxidation-reduction potential of 0.6 V or more (relative to a standard hydrogen electrode), it is possible to obtain a polymer having good properties such as polymerization yield and conductivity.
When the oxidation-reduction potential is less than 0.6 V, monomers such as aniline are hardly polymerized, and when it is more than 2.5 V, decomposition of the monomer may occur, which is not preferable.

The oxidizing agent that can be used is not particularly limited as long as it has the above-mentioned oxidation-reduction potential, but preferably includes ferric salt, persulfate, hydrogen peroxide, bichromate and the like. No. Specifically, as the ferric salt, ferric perchlorate, ferric periodate, ferric borofluoride, ferric hexafluorophosphate, ferric sulfate,
Ferric nitrate, ferric chloride, and the like.Persulfates include ammonium persulfate, sodium persulfate, potassium persulfate, and the like, and dichromates include potassium dichromate and dichromium. Preferred are sodium acid and the like. Among them, ferric perchlorate, ferric periodate,
Ferric borofluoride, ferric hexafluorophosphate, ammonium persulfate, and hydrogen peroxide are preferred because particularly good results are obtained. The amount of the oxidizing agent to be used varies depending on the type of the oxidizing agent, but is usually 0.1 to 5 moles,
Preferably 0.1 to 2 times, more preferably 0.5 to 2 times.
Twice molar is preferred. Anions of an oxidizing agent other than hydrogen peroxide or anions generated after the oxidation reaction are taken into the polymer which is a polymerization product, and can be removed by a method described later.

In the polymerization, an acid which is stable at the time of polymerization, forms a salt with a monomer, and is dissolved in an aqueous solution is used. Preferred examples of such an acid include perchloric acid, borofluoric acid, hexafluorophosphoric acid, periodic acid, sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid and the like. , Hydrofluoric acid, hexafluorophosphoric acid, and periodic acid are preferred. The addition amount of these acids may be at least the equivalent of the monomers used.

The concentration of the monomer used in the reaction is not particularly limited, and the reaction is usually carried out at a solubility or lower. It may be dissolved and used in excess. Usually, it may be performed at 0.1 mol / liter or more. The purity of the monomer is not particularly limited, and it is sufficient that the purity is 95% or more. In the reaction, the oxidizing agent may be added to the acidic solution containing the monomer or the solution containing the slurry of the monomer salt as it is or as a solution containing the oxidizing agent, followed by stirring. There are no particular restrictions on the reaction temperature and reaction time,
Usually, the reaction is carried out at a temperature higher than the freezing point of the solution containing the monomer and lower than the boiling point. However, in order to obtain a molecule having high solubility, it is preferable to carry out the reaction at a temperature of 50 ° C. or lower, preferably 40 ° C. or lower.

Before doping for obtaining conductivity, it is necessary to remove anions incorporated during the reaction as described above. As a method for removing anions, washing may be performed with a solution of an alkaline compound that does not react with the polymer. The alkali used is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, hydrazine, and alkylamine. The solution using these may have a pH of 11 or more after washing the polymer. The polymer thus obtained is, for example, a preferred polyaniline,
Generally, it has a structure represented by the following formula (I).

[0023]

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The polymer from which anions have been removed is dissolved in a solvent, and an organic acid or the like as a dopant is mixed and reacted, and then cast on a flat plate such as a glass plate and dried to form a film, or After casting on a flat plate such as a plate and drying to form a film, the film is immersed in a solution in which an organic acid is dissolved to perform doping.

The solvent for the polymer is not particularly limited. For example, N, N-dimethylformamide,
N, N-dimethylacetamide, dimethylsulfoxide, propylene carbonate, γ-butyrolactone, N
-Methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Among them, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl- 2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone is preferred.
These solvents are generally used in an amount of 0.2 to 20% by weight, preferably 1 to 10% by weight. The thickness of the film is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm
In particular, a range of 10 to 100 μm is preferable. When determining the thickness of the film, it is good to consider the decrease in thickness due to heat compression.

As a method of doping the obtained polymer film with a dopant, the polymer film may be immersed in a solution of an organic acid. As an acid having sufficient conductivity and high stability, a protonic acid having a dissociation constant pKa of 4.8 or less is preferable. Specifically, inorganic acids such as perchloric acid, borofluoric acid, sulfuric acid, and nitric acid; acetic acid, n-butyric acid, pentadecafluorooctanoic acid, pentafluoroacetic acid, trifluoroacetic acid, trichloroacetic acid, dichloroacetic acid, and monofluoroacetic acid Aliphatic carboxylic acids such as acetic acid, monobromoacetic acid, monochloroacetic acid, cyanoacetic acid, acetylacetic acid, nitroacetic acid, and triphenylacetic acid; benzoic acid, m-bromobenzoic acid, o-chlorobenzoic acid, p-, m-, o- Nitrobenzoic acid, p-, m-, o-nitrobenzoic acid, 2,4-dinitrobenzoic acid, 3,5-dinitrobenzoic acid, picric acid, trimethylbenzoic acid, p-, m-cyanobenzoic acid,
Thymol blue, salicylic acid, 5-aminosalicylic acid,
aromatic carboxylic acids such as o-methoxybenzoic acid; 1,6-
Phenol derivatives such as dinitro-4-chlorophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, p-oxybenzoic acid and bromophenol blue; mandelic acid, phthalic acid, isophthalic acid, maleic acid, fumaric acid, Substituted carboxylic acids such as dicarboxylic acids such as malonic acid, tartaric acid, citric acid, lactic acid and succinic acid; amino acids such as α-alanine, β-alanine and glycine; glycolic acid, thioglycolic acid, ethylenediamine-N, N ′
And polyvalent carboxylic acids such as -diacetic acid and ethylenediamine-N, N, N ', N'-tetraacetic acid.

Further, metanilic acid, sulfanilic acid, allylsulfonic acid, lauryl sulfate, 1-propanesulfonic acid, 1-butanesulfonic acid, 1-hexanesulfonic acid,
1-heptanesulfonic acid, 1-octanesulfonic acid, 1
Alkylsulfonic acids such as dodecanesulfonic acid and 3-cyclohexylaminopropanesulfonic acid; benzenesulfonic acid, styrenesulfonic acid, p-toluenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, butylbenzenesulfonic acid, and pentylbenzenesulfonic acid. , Hexylbenzenesulfonic acid, heptylbenzenesulfonic acid, octylbenzenesulfonic acid, nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, 3, 5-dichloro-2-hydroxybenzenesulfonic acid, xylenesulfonic acid, diethylbenzenesulfonic acid, dipropylbenzenesulfonic acid,
Alkyl benzene sulfonic acids such as dibutyl benzene sulfonic acid, trimethyl benzene sulfonic acid, styrene sulfonic acid; methyl naphthalene sulfonic acid, ethyl naphthalene sulfonic acid, propyl naphthalene sulfonic acid, butyl naphthalene sulfonic acid, pentyl naphthalene sulfonic acid, hexyl naphthalene sulfonic acid , Heptyl naphthalene sulfonic acid, octyl naphthalene sulfonic acid, nonyl naphthalene sulfonic acid, decyl naphthalene sulfonic acid,
Undecylnaphthalenesulfonic acid, dodecylnaphthalenesulfonic acid, pentadecylnaphthalenesulfonic acid, octadecylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, diethylnaphthalenesulfonic acid, dipropylnaphthalenesulfonic acid, diisopropylnaphthalenesulfonic acid, dibutylnaphthalenesulfonic acid, dipentylnaphthalene Alkyl naphthalene sulfones such as sulfonic acid, dihexyl naphthalene sulfonic acid, diheptyl naphthalene sulfonic acid, dioctyl naphthalene sulfonic acid, dinonyl naphthalene sulfonic acid, trimethyl naphthalene sulfonic acid, triethyl naphthalene sulfonic acid, tripropyl naphthalene sulfonic acid, and tributyl naphthalene sulfonic acid. Acids; furthermore, aminonaphtholsulphonic acid, camphorsulfonic acid Acrylamide -t- butyl sulfonic acid, anthraquinone sulfonic acid, etc. isoquinoline sulfonic acid, and more may be used polyfunctional acid. For example, alkyl disulfonic acids such as ethane disulfonic acid, propane disulfonic acid, butane disulfonic acid, pentane disulfonic acid, hexane disulfonic acid, heptane disulfonic acid, octane disulfonic acid, nonane disulfonic acid, and decane disulfonic acid; benzene disulfonic acid;
Toluene disulfonic acid, ethylbenzene disulfonic acid,
Propylbenzenedisulfonic acid, butylbenzenedisulfonic acid, dimethylbenzenedisulfonic acid, diethylbenzenedisulfonic acid, dipropylbenzenedisulfonic acid,
Alkylbenzene disulfonic acids such as dibutylbenzene disulfonic acid; naphthalenedisulfonic acid and methylnaphthalenedisulfonic acid, ethylnaphthalenedisulfonic acid;
Propylnaphthalenedisulfonic acid, butylnaphthalenedisulfonic acid, pentylnaphthalenedisulfonic acid, hexylnaphthalenedisulfonic acid, heptylnaphthalenedisulfonic acid, octylnaphthalenedisulfonic acid, nonylnaphthalenedisulfonic acid, dimethylnaphthalenedisulfonic acid, diethylnaphthalenedisulfonic acid, dipropylnaphthalenedisulfonic acid Alkylnaphthalenedisulfonic acids such as dibutylnaphthalenedisulfonic acid and diheptylnaphthalenedisulfonic acid; other polyphthalic sulfonic acids such as naphthalenetrisulfonic acid and naphthalenetetrasulfonic acid; and anthracenedisulfonic acid, anthraquinonedisulfonic acid and phenanthylenedisulfonic acid ,
Fluorenone disulfonic acid, carbazole disulfonic acid, diphenylmethane disulfonic acid, biphenyl disulfonic acid, diphenyl sulfone disulfonic acid, terphenyl disulfonic acid, terphenyl trisulfonic acid, naphthalene sulfonic acid-formalin condensate, anthracene sulfonic acid-formalin condensate, fluorene Sulfonic acid-formalin condensate, carbazole sulfonic acid-formalin condensate and the like can be mentioned.

Further, Modant Brown 7, Brilliant Blue FCF, Acid Yellow 3, Acid Yellow 23, Acid Blue 74, Acid Blue 92,
Dispersive dyes or reactive dyes such as Reactive Blue 19, Reactive Black 5, Reactive Yellow 13, Reactive Yellow 14, and Reactive Yellow 17 can be used.

The organic acid used in the present invention may be a polymer. For example, polystyrenesulfonic acid, polyvinylsulfonic acid, polyvinylsulfuric acid, sulfonated styrene-butadiene copolymer, polyallylsulfonic acid, polymethallylsulfonic acid, poly-2-acrylamide-2
-Methylpropanesulfonic acid, polyhalogenated acrylic acid, polyisoprenesulfonic acid, N-sulfoalkylated polyaniline, nucleated sulfonated polyaniline and the like. Further, a fluoropolymer such as Nafion (registered trademark of DuPont) can also be used as the polymer.

In the present invention, as an organic acid capable of obtaining a high electric conductivity, an acid having a pKa of 4.5 or less is preferable. However, if the ionization potential of the polymer is small, pKa = 4.
An acid exceeding 5 and having a small electron affinity may be used. For example, a polymer of an alkoxy-substituted aniline, which is an electron-withdrawing substituent, may be used. Specifically, methoxyaniline, ethoxyaniline, isopropoxyaniline, butoxyaniline, 2,4-dimethoxyaniline, 2,5-
Examples include dimethoxyaniline, 5-chloro-2-methoxyaniline, 5-chloro-2-ethoxyaniline, 3-phenoxyaniline, 4-phenoxyaniline and the like.
Particularly preferred acids generally include polyvalent organic acids such as dodecylbenzenesulfonic acid, polyvinylsulfonic acid, polystyrenesulfonic acid, naphthalenedisulfonic acid, and ethanedisulfonic acid. The concentration of such an organic acid is generally preferably in the range of 1 to 30% by weight, particularly preferably in the range of 10 to 20% by weight, and the immersion time is preferably 1 minute or more and 24 hours or less. The conductivity depends on the immersion time. Generally, the longer the immersion is, the higher the conductivity is. However, the polymer may be deteriorated.

In general, the above method requires a long time for doping. For example, when the above-described polyaniline is used as a polymer, it is preferably reduced to a polyaniline having a structure represented by the following formula (II), and then the organic acid is removed. The oxidation is preferably performed using a ferric salt having an anion as a counter ion.
By oxidizing the polyaniline having the structure of the formula (II), the structure becomes the structure represented by the above formula (I) and exhibits conductivity.

[0032]

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As the reducing agent, hydrazine compounds such as phenylhydrazine, hydrazine, hydrazine hydrate, hydrazine sulfate and hydrazine hydrochloride, and metal hydride compounds such as lithium aluminum hydride and lithium borohydride can be used. Particularly preferably, hydrazine hydrate and phenylhydrazine are preferable in that no residue is generated after the reduction reaction.

The polymer thus obtained, preferably polyaniline having an imino-p-phenylene structural unit as a main repeating unit, is dissolved in a predetermined solvent,
Further, this solution is cast on a suitable substrate and dried to prepare a polymer film. Next, the polymer film is immersed in a solution (dope solution) in which a ferric salt having an organic acid anion as a counter ion is dissolved, and is subjected to an oxidation treatment to impart conductivity to the polymer film. The conductivity of the polymer film is preferably about 10 to 100 S / cm.

Such a dope solution is disclosed in, for example,
As described in JP 170616, it is usually obtained by reacting ferric hydroxide with an excess of an organic acid. Due to the use of excess organic acid, such a dope contains an excess of organic acid anions. The ferric hydroxide can be obtained, for example, by neutralizing an aqueous solution of ferric chloride or ferric sulfate with an alkali, and washing the resulting precipitate.

The usable organic acids are the same as those described above. The molar ratio of ferric ion and organic acid in the dope solution is not limited as long as the doping proceeds,
Usually, the equivalent ratio of organic acid / ferric ion is 1 to 200, and particularly preferably 1 to 100.

After the above doping treatment, the conductive polymer film is washed and dried using a suitable bathing agent such as ethanol and acetone.

The conductive polymer film according to the present invention comprises:
The conductive polymer is not limited to the polyaniline exemplified above, and any solvent-soluble conductive polymer can be used. For example,
Polyalkylthiophenes such as polybutylthiophene, polyhexylthiophene, polyoctylthiophene, polydodecylthiophene and copolymers thereof, and polyalkylpyrroles such as polybutylpyrrole, polyhexylpyrrole, dodecylpyrrole and copolymers thereof, etc. is there. Alternatively, a solubilized organic acid substituted with an organic acid substituted with a relatively long-chain alkyl group may be used.

As the dielectric usable in the present invention, oxides of metals having a valve action, such as aluminum, tantalum, niobium, titanium, zirconium, magnesium and silicon, can be preferably mentioned. As the form, a product obtained by etching a high-purity metal foil is preferable.
Therefore, it is most preferable that the surface of the etched aluminum foil is oxidized. The etching may be performed by a known technique, and generally, chemical etching or electrochemical etching can be used. In the case of aluminum, the aluminum foil is made porous by pre-treatment such as degreasing and dissolving of the surface film in an electrolytic solution mainly containing hydrochloric acid, thereby dramatically increasing the surface area. After etching,
The adhered Cl- and powdery Al are removed by ultrasonic cleaning. Next, a dielectric film is formed by anodic oxidation. The anodic oxidation is performed by using a solution of a neutral electrolyte such as boric acid-ammonium borate, ammonium phosphate, ammonium adipate, at 130% to 20% of the rated voltage.
This is performed by applying a voltage of 0%. Before the anodic oxidation, the Al foil is immersed in boiling water to form a pseudo boehmite film [Al ₂ O ₃ .x
When H ₂ O (x = 2.0 to 2.7)] is formed, the efficiency of forming a barrier film is high and the leakage current is small.

Alternatively, aluminum or the like is plated on a surface on which a hard and durable thin film such as Ni foil is etched,
The dielectric film may be formed by oxidation. According to this method, the risk of damage to the wall surface of the fine hole during heating and pressing is reduced, and the yield is improved. The thickness of the surface oxide film is usually about 0.03 to 0.1 μm, and the fine pores on the surface are usually about 5 to 300 μF / cm ² , preferably 10 to 200 μm.
It is about F / cm ² .

After a lead wire is attached to the metal side of the thin film thus manufactured by spot welding or the like, a conductive polymer film is laminated on the dielectric film side of the metal foil, and the conductive polymer film is A temperature above the softening point and below the decomposition point, preferably 100 ° C to 200 ° C, particularly 130 ° C to 1 ° C.
While heating to 80 ° C., a pressure of 300 kg / cm ² or more, preferably 300 kg / cm ^{2 to} 800 kg / cm ² , especially 500 kg / cm ²
by applying a pressure of ^{kg / cm 2 ~700kg / cm 2} , preferably 10 minutes to 2 hours, thermocompression bonding, especially 30 to 60 minutes. Cooling is preferably performed gradually during pressurization, rather than after cooling. In addition, it is preferable to apply pressure while heating slowly without heating and pressing rapidly. By doing so, the conductive polymer enters the minute space,
Filled securely. Further, the density is increased, and the conductivity is further increased.

Such a method is described, for example, in US Pat.
As described in U.S. Pat. No. 426,633 and Japanese Patent Publication No. 5-9921, it is used for bonding a metal foil to be an electrode of a low-resistance polymer PTC. That is, a PTC body in which a conductive filler such as polyethylene, polyvinylidene fluoride and carbon black is mixed, and a Ni foil roughened by etching or the like are laminated and heat-pressed.
In this case, there is no dielectric layer and conductivity is required, but an extremely small resistance value can be obtained. According to observation with a microscope, the fine space of the electrode foil is completely filled with the PTC element body. In this example, the purpose is to obtain conductivity, which is different from the object and material system of the present invention. A carbon paste and then a silver paste are applied to the conductive polymer film, and the electrode is taken out. Next, the whole may be resin-sealed.

Alternatively, a carbon paste may be applied to both surfaces of a metal foil such as copper serving as a cathode, and an aluminum foil having a dielectric film serving as an anode may be laminated on both sides of the paste, followed by thermocompression bonding. Both sides may be etched and an anode may be formed around an Al foil on which an oxidized dielectric film is formed. A conductive polymer, a carbon paste, a silver paste or a metal foil may be laminated in this order on both sides, and then heat-pressed. Considering the transfer of heat from the press, the former in which a dielectric film exists on the press side is preferable.

Further, by repeating the same structure to form a laminated structure, it is very easy to increase the total capacity.

Next, a specific configuration example of the organic solid electrolytic capacitor of the present invention will be described with reference to the drawings. 1 and 2 are schematic cross-sectional views showing a specific configuration example of the solid electrolyte capacitor of the present invention.

For example, as shown in FIG. 1, fine holes are formed by etching in a metal foil 2 preferably having a thickness of 50 to 800 μm and having a valve action, and an oxide film 3 is further formed. Further, after washing with water, an organic solvent or the like, it is dried. Next, a cathode having a carbon paste 4 applied to both surfaces of a cathode constituting metal 5 such as a copper foil is sandwiched between conductive polymer films 1, and the metal foil 2 having the above-mentioned valve action serving as an anode is provided outside the cathode.
The oxide film 3 side is overlaid and heated and pressed under the above-mentioned heating and pressing conditions.

This is cut into a predetermined size, and as shown in FIG. 2, an external electrode 6 is connected to the outer metal foil 2 having a valve action to form an anode, and the end 5a of the central metal 5 constituting the cathode is used as a cathode. A lead wire or the like is connected together with the external electrode 6 as a take-out electrode, and if necessary, sealed in a resin or metal case to form a capacitor.

The organic solid electrolytic capacitor of the present invention is used for a wide range of applications as a power supply bypass capacitor for electronic equipment requiring a large capacity and a low ESR, such as a personal computer, a mobile phone, a video camera, and a digital camera.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Polyaniline and polyaniline compositions are available from Y.CAO, A.ANDE
RETTA, AJHEEGER, POLYMER, 30 (1989) 2305;
Synthesis was performed based on JP-A-508390 and JP-A-7-331067.

<Production of quinone diimine / phenylenediamine type conductive polyaniline> Distilled water 60 was placed in a 1-liter three-necked flask equipped with a stirrer, a thermometer, and a straight tube adapter.
0 g, 50 ml of 35% hydrochloric acid and 40 g of aniline (0.4 g).
3 mol) were added in order to dissolve the aniline. Separately, 97% concentrated sulfuric acid was added to 149.3 g of distilled water while cooling with ice.
4 g (0.43 mol) was added to prepare an aqueous sulfuric acid solution. This aqueous sulfuric acid solution was added to the separable flask, and the entire flask was cooled to −4 ° C. Next, 98 g of ammonium peroxodisulfate (0.2 g of distilled water) was added to 220 g of distilled water.
43 mol) and dissolved to prepare an oxidizing agent aqueous solution.

The above-mentioned aqueous solution of ammonium peroxodisulfate was slowly (1 ml / min or less) added dropwise to an acidic aqueous solution of aniline while stirring and stirring the entire flask in a thermostat at a reaction temperature of -3 ° C. or lower. Initially, the colorless and transparent solution gradually turned from green-blue to black-green, and a black-green powder eventually precipitated.

The reaction during the precipitation of the powder generates heat. However, in order to obtain a high molecular weight polymer, the reaction temperature must be kept at 0 ° C. or lower, preferably -3 ° C. or lower. After powder deposition, the dropping rate of the aqueous solution of ammonium peroxodisulfate may be increased by about 10 times, but it is necessary to adjust the reaction temperature so as to keep it at -3 ° C or lower. After the dropping of the aqueous solution of ammonium peroxodisulfate was completed over about 7 hours, the mixture was further stirred at a temperature of −3 ° C. or lower for 1 hour.

The obtained polymer was separated by filtration, washed with water and acetone, and dried at 50 ° C. under reduced pressure. Black-green quinone diimine / phenylenediamine type conductive polyaniline 43g
I got This was press-formed to a diameter of 13 mm and a thickness of 0.7 mm, and the conductivity was measured. As a result, it was 14 S / cm.

<Production of quinone diimine / phenylenediamine type solvent-soluble polyaniline by undoping> 35 g of the above-mentioned doped conductive polyaniline powder was mixed with 2 g of
The mixture was added to 400 ml of N ammonia water and stirred at 5,000 rpm for 5 hours with a homogenizer while cooling. The mixture turned from black green to bluish purple.

The powder was collected by filtration using a Kiriyama funnel, and then washed with distilled water until the filtrate became neutral while stirring in a beaker. Further, the filtrate was washed with acetone until it became colorless. The powder was dried under reduced pressure at 50 ° C. for 2 hours to obtain 28 g of a black-brown undoped solvent-soluble quinonediimine / phenylenediamine type polyaniline powder. This polyaniline is soluble in N-methyl-2-pyrrolidone and has a solubility of 8 g / 100 g (7.4%).

<Preparation of Conductive Film: Preparation Example 1> 0.5 g of the above polyaniline and 1.8 g of dodecylbenzenesulfonic acid were mixed well in a nitrogen atmosphere, and then xylene 2
After suspending the suspension in 5 g and stirring with an ultrasonic cleaner for 48 hours, insoluble matters were precipitated by a centrifuge and removed by decantation. The obtained xylene solution was applied on a polyester film and dried at 120 ° C. for 1 hour. After obtaining a film, the film was washed with acetone and dried. The conductivity of the film measured by a digital multimeter was 80 S / cm.

<Preparation of Conductive Film: Preparation Example 2> An aqueous solution in which a 25% aqueous solution of sodium polyvinyl sulfonate was converted to an acid form using an ion exchange resin was concentrated and solidified. Separately, 1.47 g of ferric sulfate hydrate was dissolved by heating in 50 g of distilled water to obtain a reddish brown transparent solution. While stirring, 3.15 g of a 5N aqueous sodium hydroxide solution was added to obtain colloidal iron hydroxide. After centrifugation, the supernatant was discarded by decantation, and then distilled water was added to wash with stirring. This was repeated until the waste liquid reached 200 ml.

2.2 g of the polyvinyl sulfonic acid was added to the iron hydroxide colloid solution thus obtained.
The colloid dissolved with the exotherm to give a clear reddish brown solution. Add distilled water to this until the total amount becomes 11 g,
An aqueous solution of ferric polyvinyl sulfonate (dope solution) was prepared.

1.90 g of phenylhydrazine was dissolved in 90 g of N-methyl-2-pyrrolidone, and then 10 g of the solvent-soluble quinonediimine / phenylenediamine type polyaniline was dissolved. The solution changes color from dark blue to dark brown, and at the same time, generation of nitrogen gas is observed. After the solution was filtered under reduced pressure, it was cast on a glass plate,
C. for 1 hour to produce a polyaniline film having a thickness of 20 to 45 .mu.m. This film was immersed in the dope solution for one hour and dried at 50 ° C. for one hour. The conductivity of the film was 43 S / cm.

<Preparation of Conductive Film: Preparation Example 3> 10.4 g of m-cresol, in which 0.5 g of solvent-soluble quinone diimine / phenylenediamine type polyaniline and 0.65 g of camphorsulfonic acid were well mixed in a nitrogen atmosphere, was added. After treating with an ultrasonic cleaner for 48 hours, insolubles were separated by a centrifuge and removed by decantation. The obtained solution was cast on a glass plate and dried at 150 ° C. for 1 hour to obtain a conductive film. The conductivity was 180 S / cm. <Preparation of Conductive Film: Preparation Example 4> 0.5 g of solvent-soluble quinone diimine / phenylenediamine type polyaniline, 0.9 g of dodecylbenzenesulfonic acid and 1.05 g of 3-pentadecylphenol were mixed well in a nitrogen atmosphere. This mixture was added to 12.6 g of xylene, and the mixture was stirred for 48 hours with an ultrasonic washer. Then, insolubles were separated by a centrifugal separator and removed by decantation. The obtained solution was cast on a glass plate and dried at 120 ° C. for 1 hour to obtain a film. The film was washed with acetone to remove 3-pentadecylphenol to obtain a desired conductive polyaniline film. The conductivity of the film is 50 S / cm
Met.

<Preparation of Solid Electrolytic Capacitor> Example 1 As shown in FIG. 1, a 70 μm-thick aluminum foil 2 having fine holes (25 μF / cm ² ) formed by etching was treated with 10% by weight of ammonium adipate. The oxide film 3 was formed in an aqueous solution at 60 ° C. and 40 V, washed with water, washed with acetone, and dried. The thickness of the oxide film is
It was 0.052 μm. Two conductive polymer films 1 prepared in Preparation Example 1 were sandwiched by a cathode coated with a carbon paste 4 on both surfaces of a copper foil 5, and an oxide film 3 side of an aluminum foil 2 serving as an anode was overlapped on the outside thereof. , 150 ° C, 7
Heating and crimping were performed at 00 kg / cm ² for 20 minutes.

This is cut into 10 mm × 10 mm, and external electrodes 6 are connected to both outer aluminum foils 2 as an anode and a copper foil 5 in the center is used as a cathode 5a as shown in FIG.
No. 1. The frequency characteristics of the obtained capacitor were measured, and the results are shown in FIG.

Example 2 A capacitor No. 2 was produced in the same manner as in Example 1 except that the conductive polymer film produced in Production Example 2 was used.

Example 3 A capacitor No. 3 was produced in the same manner as in Example 1 except that the conductive polymer film produced in Production Example 3 was used.

Example 4 A capacitor No. 4 was produced in the same manner as in Example 1 except that the conductive polymer film produced in Production Example 4 was used.

Example 5 Anodized aluminum foil was etched from both sides under the same conditions as in Example 1 to form a dielectric film. The conductive polymer film prepared in Preparation Example 1 was placed on both sides thereof, and a copper foil coated with a conductive carbon paste was placed on the outside of the conductive polymer film.
/ Cm ² for 20 minutes. This is 10mm x 1
The capacitor was cut to 0 mm to produce a capacitor No. 5.

Example 6 A capacitor No. 6 was produced in the same manner as in Example 5, except that the conductive polymer film produced in Production Example 2 was used. The frequency characteristics of the obtained capacitor were measured, and the results are shown in FIG.

Example 7 A capacitor No. 7 was produced in the same manner as in Example 5 except that the conductive polymer film produced in Production Example 3 was used.

Comparative Example 1 A lead wire was spot-welded to the aluminum foil with a dielectric (10 mm × 10 mm) used in Example 1, immersed in the polyaniline and the dopant solution in Preparation Example 5 for 5 minutes, dried, and acetone And washed twice. This was repeated three times to obtain an electrolyte membrane. A conductive carbon paste and a silver paste were applied in this order, and a lead wire was taken out using the silver paste to obtain a capacitor No. 8.

Comparative Example 2 The same aluminum foil as in Comparative Example 1 was immersed in a solution of a solvent-soluble quinone diimine / phenylenediamine type polyaniline in N-methyl-2-pyrrolidone for 5 minutes. After drying, immersion and drying were repeated two more times.
Finally, it was washed with acetone three times and dried. Furthermore, after being immersed in the dope solution of Example 2 for 1 hour, acetone washing was performed.
This was dried to obtain a capacitor No. 9.

The initial capacity and initial tan of the above capacitor
Table 1 shows δ, equivalent series resistance ESR, leakage current, and results of a stability test after storage at 105 ° C.

[0072]

[Table 1]

[0073]

As described above, according to the present invention, a uniform conductive polymer film equivalent to or more than the conventional electrolytic polymerization method, low-temperature chemical polymerization method, and dipping method can be obtained.
In addition, since no solution is used in the capacitor manufacturing process, a capacitor having uniform characteristics can be obtained with a very simple process.

Further, it is possible to provide a capacitor which is uniform in doping, has no extra residual dopant, is excellent in reliability, has a sufficiently low resistance value (ESR) by heating and crimping, and has excellent frequency characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of a solid electrolytic capacitor of the present invention, showing a state before thermocompression bonding.

FIG. 2 is a schematic cross-sectional view showing a configuration example of a solid electrolytic capacitor of the present invention, showing a state where external electrodes are attached after thermocompression bonding.

FIG. 3 is a diagram showing impedance-frequency characteristics of samples 1 and 3 of the present invention. Reference Signs List 1 conductive polymer film 2 metal foil having valve action (aluminum foil) 3 dielectric film 4 conductive carbon paste layer 5 cathode constituent metal (copper foil) 6 external electrode

Claims (5)

[Claims] 1. A roughened metal foil having a dielectric oxide film on the surface, a conductive polymer film contacted and integrated with the roughened metal foil, and another conductive polymer layer An organic solid electrolytic capacitor having a negative electrode on its surface, wherein the roughened metal foil and a conductive polymer film are thermocompression bonded. 2. The organic solid electrolytic capacitor according to claim 1, wherein the conductive polymer film is an organic solvent-soluble conductive polymer using an organic acid as a dopant. 3. The organic solid electrolytic capacitor according to claim 2, wherein the soluble conductive polymer is a substituted or unsubstituted polyaniline, polypyrrole, or polythiophene. 4. An organic solid electrolytic method comprising: thermocompression bonding a conductive polymer film to a roughened metal foil having a dielectric oxide film on its surface; and forming a negative electrode on another surface of the conductive polymer layer. Manufacturing method of capacitor. 5. A conductive polymer film is thermocompression-bonded to the surface-roughened metal foil at a temperature not lower than the softening point and not higher than the decomposition point of the conductive polymer film and at a pressure not lower than 300 kg / cm ^2. A method for manufacturing an organic solid electrolytic capacitor according to claim 4.