JP2003022937A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor which has an excellent water resistance and excellent resistances to humidity and heat at a high temperature and humidity, has excellent durability and reliability, an excellent adhesion between a solid electrolyte and a dielectric coating, has a small resistance in a high frequency regions, and a large electrostatic capacity; and also to provide a method for manufacturing the solid electrolytic capacitor. SOLUTION: In the solid electrolytic capacitor, a dielectric film is provided on a film formation metal, and a film made of a conductive polyaniline composition containing polyaniline doped in phenol-sulfonic acid novolac resin is provided on the dielectric film as a solid electrolyte. In the method for manufacturing a solid electrolytic capacitor, a dielectric film is formed on a film formation metal, a polyaniline film is formed on the dielectric film, an aqueous solution of phenol-sulfonic acid novolac resin is brought into contact with the polyaniline film, and the polyaniline is doped with the phenol-sulfonic acid novolac resin.

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 using a conductive polyaniline composition having excellent water resistance as a solid electrolyte membrane and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, electrolytic capacitors known as large-capacity capacitors include an electrolytic solution type and a solid electrolyte type. Among these, as a solid electrolyte type capacitor using a solid electrolyte, that is, as a solid electrolytic capacitor, a method using manganese dioxide or 7,7,8,8-tetracyanoquinodimethane (TCNQ) complex is known. The former has various problems such as a large impedance and the latter has poor thermal stability.

Therefore, in recent years, various solid electrolytic capacitors using a conductive organic polymer as a solid electrolyte have been proposed. For example, JP-A-63-158829 discloses that
Aluminum is vacuum-deposited on an aluminum foil on the surface of which a dielectric material made of aluminum oxide is formed, and this is used as an anode, and an aqueous solution containing pyrrole together with a supporting electrolyte is electrolytically oxidized between the aluminum foil and the cathode made of stainless steel. Describes producing a conductive polypyrrole film to obtain a solid electrolytic capacitor.

However, according to this method, since the dielectric film made of aluminum oxide is insulative, the conductive polypyrrole film cannot be directly formed on it by electrolytic polymerization. That is, an operation such as vapor deposition of aluminum on the surface of the dielectric film is required in advance, the manufacturing process is complicated, and the manufacturing cost is inevitably high.

In Japanese Patent Laid-Open No. 63-173313, a dielectric oxide film is formed on a film forming metal, polypyrrole is deposited on the dielectric oxide film by chemical oxidative polymerization of pyrrole, and this is used as a conductive layer. It is described that a layer is used as an electrode, and pyrrole is electropolymerized thereon, and a conductive polymer composed of the polypyrrole is laminated as a solid electrolyte. In addition, JP-A-1-253
Similarly, JP-A No. 226 describes that a conductive layer made of manganese dioxide is formed on a dielectric film, and polypyrrole or polythiophene is laminated thereon by electrolytic polymerization to obtain a solid electrolyte.

However, according to any of these methods, it is necessary to laminate polypyrrole or the like on the dielectric film which is not a conductor by electrolytic reaction, which is a problem. That is, a chemical oxidative polymerization film layer or a manganese dioxide layer must be provided on the dielectric film as a conductive layer to serve as an electrode for electrolytic polymerization. It's very complicated.

Similarly, as described in JP-A-6-310380, a method of forming a conductive organic polymer on a dielectric film by only chemical oxidative polymerization is also known. According to this method, it is not necessary to previously form a conductive layer on the dielectric film, but there are various problems such that the control of the polymerization reaction is not easy.

On the other hand, the present inventors have succeeded in obtaining polyaniline which is soluble in various organic solvents and has a very high molecular weight, and a solution of this polyaniline is applied onto an appropriate substrate. It has been found that a self-supporting film can be obtained, and that a film made of a conductive polyaniline composition can be obtained by doping the film with a protonic acid.

[0009]

Therefore, the inventors of the present invention have earnestly studied to develop a solid electrolytic capacitor using such a conductive polyaniline composition as a solid electrolyte.
As a result of conducting research, a conductive polyaniline composition having dramatically improved water resistance can be obtained by doping polyaniline with a phenol sulfonic acid novolac resin, and such a conductive polyaniline composition can be used as a solid electrolyte. By using as, excellent water resistance and heat and humidity resistance under high temperature and high humidity, therefore, with excellent durability and reliability, excellent adhesion between the solid electrolyte and the dielectric film, the impedance in the high frequency region is small, The present invention has been completed by finding that a solid electrolytic capacitor having a large capacitance can be obtained.

That is, the present invention is excellent in water resistance and heat and humidity resistance under high temperature and high humidity, and therefore is excellent in durability and reliability, and is also excellent in adhesion to a dielectric film, and has a low impedance in a high frequency region. An object of the present invention is to provide a solid electrolytic capacitor having a large capacitance and a method for manufacturing such a solid electrolytic capacitor.

[0011]

According to the present invention, a film made of a conductive polyaniline composition having a dielectric film on a film-forming metal and polyaniline doped with a phenol sulfonic acid novolak resin is provided above. There is provided a solid electrolytic capacitor having a solid electrolyte on a dielectric film.

Further, according to the present invention, after forming a dielectric film on the film-forming metal, a polyaniline film is formed on the dielectric film, and then an aqueous solution of phenolsulfonic acid novolac resin is formed on the polyaniline film. Contact them,
Provided is a method for producing a solid electrolytic capacitor, which comprises doping the polyaniline with the phenolsulfonic acid novolac resin.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A solid electrolytic capacitor according to the present invention comprises a conductive polyaniline composition having a dielectric film on a film-forming metal and polyaniline doped with a novolac phenolsulfonate resin. It has as a solid electrolyte on the dielectric film.

According to the present invention, such a solid electrolytic capacitor, after forming a dielectric film on a film-forming metal,
A polyaniline film is formed on this dielectric film, and then
It can be obtained by bringing the polyaniline film into contact with an aqueous solution of a phenolsulfonic acid novolac resin and doping the polyaniline with the phenolsulfonic acid novolac resin.

According to the present invention, the surface of a film-forming metal foil having a roughened surface or a porous sintered body obtained by sintering fine powder of a film-forming metal is electrolytically oxidized to form a film. A dielectric film made of the oxide of the metal is formed on the surface of the metal, and then a polyaniline solution is applied on the dielectric film and the solvent is dried to form a polyaniline film. The polyaniline film is coated with phenolsulfonic acid novolak. The resin is doped, thus forming a film of the conductive polyaniline composition on the dielectric film as a solid electrolyte.

Generally, aluminum or tantalum is preferably used as the film forming metal, and therefore, a film of aluminum oxide or tantalum oxide is preferably used as the dielectric film.

The dielectric usually consists of a film of aluminum oxide or tantalum oxide, which is usually roughened in the case of aluminum and finely divided in the case of tantalum in order to increase the surface area. It is made porous by sintering powder metal. The solid electrolyte needs to adhere to the porous rough surface of the oxide film.

According to the present invention, the polyaniline solution is applied onto the dielectric film to form the polyaniline film. Therefore, the dielectric film has excellent adhesion to polyaniline.
Thus, the adhesion with a film made of a conductive polyaniline composition as a solid electrolyte obtained by doping this polyaniline is excellent. Further, according to the present invention, the thickness of the polyaniline film formed on the dielectric can be arbitrarily adjusted.
Polyaniline films of various thickness over 200 μm can be obtained. Then, by doping such a polyaniline film, its conductivity is reduced from 10 ⁻³ to 10 −10.
Range of ² S / cm, preferably 10 ⁰ ~10 ² S / cm
The range can be easily adjusted.

Moreover, according to the solid electrolytic capacitor of the present invention, as described above, the solid electrolyte is made of a conductive polyaniline film having a phenol sulfonic acid novolac resin as a dopant, and the conductivity of the conductive polyaniline film is electron conduction. Therefore, the impedance is small and the capacitance is large in the high frequency region as compared with the ion conductive electrolytic solution type capacitor. Further, as the solid electrolyte, the conductive polyaniline composition has an electric conductivity that is one to two orders of magnitude higher than that of manganese dioxide or the TCNQ complex. Therefore, the solid electrolytic capacitor according to the present invention has excellent high frequency characteristics. .

In the present invention, the polyaniline is preferably of the general formula (I)

[0021]

[Chemical 5]

(In the formula, m and n respectively represent the mole fractions of the quinonediimine structural unit and the phenylenediamine structural unit in the repeating unit, and 0 <m <1, 0 <n <1, m
+ N = 1. ) Consists of repeating units
It is soluble in an organic solvent in the undoped state, preferably has an intrinsic viscosity [η] measured at 30 ° C. in N-methyl-2-pyrrolidone of 0.40 dL / g or more, particularly preferably 1.0 dL / g. It is more than g.

Such polyaniline is disclosed in Japanese Patent Laid-Open No. 3-2.
As disclosed in Japanese Patent No. 8229, which is already known, and which is obtained by first preparing a conductive polyaniline composition doped with a protonic acid, and then dedoping the composition. You can

That is, aniline is reacted with an oxidizing agent such as ammonium peroxodisulfate in the presence of a suitable protic acid such as sulfuric acid in a suitable solvent such as water or methanol, and the precipitated powder is filtered. By taking, the conductive polyaniline composition doped with the above-mentioned protonic acid is obtained. Then, the powder is added to an aqueous solution of an alkaline substance such as ammonia to neutralize (ie, dedoping) the conductive polyaniline composition to obtain an organic solvent represented by the general formula (I). A soluble polyaniline powder is obtained.

The undoped polyaniline thus obtained has a high molecular weight and is soluble in various organic solvents. Usually in N-methylpyrrolidone at 30 ° C
Has an intrinsic viscosity [η] of 0.40 dl / g or more, and is, for example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide,
It is dissolved in an organic solvent such as dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone and sulfolane. Although the solubility of the undoped polyaniline in such an organic solvent depends on the average molecular weight and the solvent, 0.5 to 100% of polyaniline is usually dissolved to obtain a solution having a concentration of 1 to 30% by weight. be able to. In particular, this undoped polyaniline exhibits high solubility in N-methyl-2-pyrrolidone, and usually 20 to 100% of polyaniline dissolves to obtain a 3 to 30% by weight solution.

In the undoped polyaniline, the values of m and n can be adjusted by oxidizing or reducing polyaniline. That is, by reducing, m can be reduced and n can be increased. On the contrary, if oxidized, m can be increased and n can be decreased. The reduction of the quinonediimine structural unit in the polyaniline due to the reduction of the polyaniline enhances the solubility of the polyaniline in organic solvents. Also,
The viscosity of the solution is lower than that before the reduction. For the reduction of such solvent-soluble polyaniline, for example, N 2
-Dissolves in methyl-2-pyrrolidone, but N-methyl-
Phenylhydrazine is most preferably used because it does not reduce 2-pyrrolidone.

On the other hand, the oxidizing agent used for oxidizing the solvent-soluble polyaniline is not particularly limited as long as it can oxidize the phenylenediamine structural unit, but for example, mild silver oxide is preferable. Used.
If necessary, potassium permanganate, potassium dichromate, etc. can also be used.

In the present invention, the phenolsulfonic acid novolac resin is preferably of the general formula (II)

[0029]

[Chemical 6]

(Wherein R represents a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, a carboxyl group or an amino group). In particular, although not particularly limited, according to the present invention, in the above general formula (II), R is a hydrogen atom, and the substitution position of the sulfonic acid group is para to the hydroxyl group. Sulfonic acid novolac resin is preferably used.

Such a phenolsulfonic acid novolak resin can be obtained by reacting the phenolsulfonic acid with formaldehyde in the presence of an acidic catalyst.

In the present invention, the phenol sulfonic acid novolac resin is not particularly limited in its molecular weight, but normally, polystyrene sulfonic acid is used as a standard polymer, and the weight average molecular weight measured by GPC is 2000 to 800,000. Is preferred. When the molecular weight of the phenol sulfonic acid novolac resin is less than 2000, the resulting conductive polyaniline composition is not sufficiently improved in water resistance. On the other hand, when the molecular weight of the phenol sulfonic acid novolac resin is greater than 800,000, it will be described later. As described above, the viscosity of the phenol sulfonic acid novolak resin aqueous solution used for doping is too high, and it is difficult to dope polyaniline.

Thus, in the present invention, in order to form a polyaniline film on the dielectric film and dope this polyaniline film with the phenolsulfonic acid novolac resin, the polyaniline film is immersed in a solution containing the phenolsulfonic acid novolac resin. Alternatively, a solution containing a phenol sulfonic acid novolak resin may be applied to the polyaniline film, and after doping, the polyaniline film may be washed with an appropriate solvent and dried.

In the present invention, the concentration of the phenol sulfonic acid novolak resin aqueous solution used for doping the polyaniline film is not particularly limited, but is usually in the range of 2 to 50% by weight. When the concentration of the novolak resin aqueous solution is lower than 2% by weight, it takes a long time for doping, while when it exceeds 50% by weight, the viscosity of the novolac resin aqueous solution is too high and it is difficult to dope the polyaniline film.

According to the present invention, as described above, the polyaniline film can be doped also by bringing it into contact with the aqueous solution of the phenolsulfonic acid novolac resin at room temperature, but it is preferably carried out at a temperature of 50 to 100 ° C. By doing so, the doping can be completed in a shorter period of time. The time required for doping is appropriately determined depending on the electric conductivity of the obtained conductive polyaniline composition, but is usually in the range of 10 minutes to 10 hours.

[0036] In this way, when doped polyaniline film, a polyaniline film, conductivity before doping is usually about 10 ^-10 S / cm, which, after doping, usually 10 ^{0 -} 10 ^It has a conductivity as high as ² S / cm.

The film made of conductive polyaniline formed on the dielectric film in this manner exhibits extremely high water resistance. Conventionally, a conductive polyaniline composition having polyvinyl sulfonic acid as a dopant is known to have a relatively high water resistance, but even if it is immersed in distilled water for 500 hours, its electrical conductivity is as high as the initial value. Value 1
/ 400 to about 400. On the other hand, the conductive polyaniline composition having a phenol sulfonic acid novolac resin as a dopant has a decrease in conductivity of 1/10 or less even when immersed in distilled water for 500 hours.

The reason why the conductive polyaniline composition used in the present invention has such high water resistance is not always clear, and the present invention is not limited by theory, but the phenolsulfonic acid novolak resin is not limited thereto. It is believed that this is because the phenolic hydroxyl group possessed by the compound strengthens the interaction with the polyaniline, and as a result, suppresses dedoping of the phenolsulfonic acid novolak resin, which is the dopant, from the polyaniline.

A film made of conductive polyaniline formed on a dielectric film is also excellent in heat resistance, and it has been known that polyvinyl sulfonic acid is used as a dopant and has relatively high heat resistance. It has almost the same heat resistance as the conductive polyaniline composition.

The reason why the conductive polyaniline composition used in the present invention has such excellent heat resistance is not always clear, and the present invention is not limited by theory, but the polyaniline molecule is close to the polyaniline molecule. It is presumed that this is because the reducing atmosphere of the phenolic hydroxyl group possessed by the existing phenolsulfonic acid novolac resin acts to suppress the oxidative deterioration of polyaniline.

[0041]

EXAMPLES The present invention will be described below with reference to examples and reference examples, but the present invention is not limited to these examples.

Reference Example 1 (Preparation of Conductive Polyaniline Composition by Oxidative Polymerization of Aniline) Distilled water 6000 g, 3 in a 10 L separable flask equipped with a stirrer, thermometer and straight tube adapter.
360 mL of 6% hydrochloric acid and 400 g (4.295 mol) of aniline were charged in this order to dissolve the aniline. Separately, while cooling with ice water, distilled water 149 in a beaker
Add 434 g (4.295 mol) of 97% concentrated sulfuric acid to 3 g,
A sulfuric acid aqueous solution was prepared by mixing. This sulfuric acid aqueous solution was added to the separable flask, and the entire flask was cooled to -4 ° C in a low temperature constant temperature bath.

Next, 980 g (4.295 mol) of ammonium peroxodisulfate was added to 2293 g of distilled water in a beaker and dissolved to prepare an oxidizing agent aqueous solution.

The entire flask was cooled in a low temperature constant temperature bath, and while maintaining the temperature of the reaction mixture at -3 ° C or lower, the above aqueous solution of aniline salt was stirred and stirred using a tubing pump from a straight pipe adapter to the above peroxo. Aqueous ammonium disulfate solution was gradually added dropwise at a rate of 1 mL / min or less. First, the colorless and transparent solution changed from green-blue to black-green as the polymerization proceeded, and then a black-green powder precipitated.

A temperature rise is observed in the reaction mixture during this powder precipitation, but again in accordance with the invention.
In order to obtain a high molecular weight polyaniline, it is important to keep the temperature in the reaction system at 0 ° C. or lower, preferably −3 ° C. or lower. After the powder is deposited, the dropping rate of the aqueous ammonium peroxodisulfate solution may be slightly increased, for example, about 8 mL / min. However, also in this case, it is necessary to monitor the temperature of the reaction mixture and adjust the dropping rate so as to maintain the temperature at −3 ° C. or lower. Thus,
After the dropping of the aqueous solution of ammonium peroxodisulfate was completed over 7 hours, the stirring was continued for another 1 hour at a temperature of -3 ° C or lower.

The obtained powder was filtered, washed with water, washed with acetone and vacuum dried at room temperature to obtain 430 g of a powder of a black-green conductive polyaniline composition. This has a diameter of 13 mm,
It was pressed into a disk having a thickness of 700 μm, and its conductivity was measured by the van der Pauw method.
It was S / cm.

(Production of Polyaniline Soluble in Organic Solvent by Dedoping of Conductive Polyaniline Composition) Powder 35 of the above-mentioned doped conductive polyaniline composition
0 g was added to 4 L of 2N ammonia water, and the mixture was stirred for 5 hours at a rotation speed of 5000 rpm with an auto homomixer. The mixture changed from black green to blue purple.

The powder was filtered off with a Buchner funnel, washed repeatedly with distilled water while stirring in a beaker until the filtrate became neutral, and then washed with acetone until the filtrate became colorless. did. Then, the powder was vacuum dried at room temperature for 10 hours to obtain 280 g of a blackish brown dedoped polyaniline powder.

This polyaniline was soluble in N-methyl-2-pyrrolidone and had a solubility of 8 g (7.4%) in 100 g of the same solvent. Also, the intrinsic viscosity [η] measured at 30 ° C. using this as a solvent was 1.23 dl / g.

The polyaniline had a solubility of 1% or less in dimethyl sulfoxide and dimethylformamide. It was substantially insoluble in tetrahydrofuran, pyridine, 80% acetic acid aqueous solution, 60% formic acid aqueous solution and acetonitrile.

Further, the polyaniline soluble in the organic solvent in the undoped state was subjected to GPC measurement using a GPC column for N-methyl-2-pyrrolidone. As a result, the number average molecular weight was 23,000 and the weight average molecular weight was 1600.
It was 00 (both in terms of polystyrene).

Reference Example 2 10 g of polyaniline powder soluble in an organic solvent in the undoped state obtained in Reference Example 1 above was dissolved in 90 g of N-methyl-2-pyrrolidone (NMP) to prepare a 10 wt% solution. . 120 μm thick on both sides of A4 size glass plate
4 of polytetrafluoroethylene resin adhesive tape
The sheets were stacked and laminated, a bank was formed, the NMP solution of the above polyaniline was cast on the bank, and after squeezing with a glass rod, it was dried at 80 ° C. for 1 hour in a hot air circulation dryer. The polyaniline film thus obtained was peeled from the glass plate, and two 1 cm square pieces were cut out. The thickness of the obtained film was 42 μm.

A p-phenol sulfonic acid novolak resin aqueous solution (manufactured by Konishi Chemical Industry Co., Ltd., polystyrene sulfonic acid standard GPC weight average molecular weight 20000) was adjusted to a solid content concentration of 20% by weight, and then a glass sample of 50 mL capacity was prepared. Put 30g in a tube and put this sample tube at 80 ℃
It was immersed in a constant temperature bath. Thirty minutes after the start of the dipping, the above two polyaniline films were dipped in the phenol sulfonic acid novolac resin aqueous solution in the sample tube, and the doping treatment was performed for 1 hour.

After this doping treatment, each polyaniline film was taken out, washed with 30 mL of each methanol three times to remove the dopant adhering to the surface of the film, and dried in a dryer at 80 ° C. for 30 minutes, Two films made of a conductive polyaniline composition containing p-phenolsulfonic acid novolac resin as a dopant were obtained. The electric conductivity of these two films was 8.8 S / cm and 9.5 S, respectively, as a result of measurement by Van der Pauw method.
Was / cm.

Of these, a film having an electric conductivity of 8.8 S / cm was put into a 20 mL capacity glass sample tube containing 15 mL of distilled water, taken out with time, and its electric conductivity was measured. The results are shown in Fig. 1. As is apparent from FIG. 1, the film made of the conductive polyaniline composition used in the present invention has an electric conductivity of 1.3 S / cm even after being immersed in distilled water for 578 hours, and therefore, the electric conductivity during this period is kept. Changes within 1/10 of the initial conductivity,
It is shown to have high water resistance.

Further, a film having an electric conductivity of 9.5 S / cm was attached to a 10 cm square glass plate in a cross shape with an adhesive tape made of polytetrafluoroethylene resin having a width of 2 mm, and 1
Put in a hot air circulation dryer at 25 ° C, take out over time,
The conductivity was measured. The results are shown in Figure 2. As is clear from FIG. 2, the film made of conductive polyaniline used in the present invention has a heat resistance of 125 ° C.

Reference Example 3 An aqueous solution of sodium polyvinylsulfonate manufactured by Aldrich was used as a strongly acidic cation exchange resin Dowex W-50X12.
(By Dow Chemical Co., Ltd.) was used for ion exchange to obtain a 20% by weight aqueous solution of polyvinyl sulfonic acid in the free acid form.

Except for using this polyvinyl sulfonic acid as a dopant, the same procedure as in Reference Example 2 was used, except that polyvinyl sulfonic acid was used as a dopant and the conductivity was 3.7 S / cm and 7.1 S / cm, respectively. Two polyaniline films were obtained.

Of these two films, the conductivity was 3.
A 7 S / cm film was subjected to a water resistance test in the same manner as in Reference Example 2, and as shown in FIG. 1, the conductivity when immersed in distilled water for 554 hours was 9.2 × 1.
It was 0 ⁻³ S / cm, which was 1/400 of the initial conductivity.

A heat resistance test was conducted in the same manner as in Reference Example 2 using a film having an electric conductivity of 7.1 S / cm. The results are shown in Figure 2.

Example 1 As a film-forming metal, obtained by sintering fine powder of tantalum.
Volume of 20.8 mm ³85 ℃ using the porous fired body
DC voltage 30V is applied in 0.1 wt% phosphoric acid aqueous solution
On the surface of the above-mentioned porous body, a dielectric made of tantalum oxide.
A film was formed and used as a capacitor anode body.

5 parts by weight of polyaniline / N-methyl-2-pyrrolidone soluble in an organic solvent in the undoped state obtained in Reference Example 1 was dissolved in 95 parts by weight of N-methyl-2-pyrrolidone to obtain 5 parts by weight. % Solution, and the above-mentioned condensa anode body was dipped in this solution, and then dried at 80 ° C. for 20 minutes to form a polyaniline film on the condesa anode body. This operation was repeated 7 times.

The capacitor anode body thus treated was
After dipping for 6 hours in a p-phenolsulfonic acid novolak resin aqueous solution (manufactured by Konishi Chemical Industry Co., Ltd., weight average molecular weight by polystyrene standard GPC of 20000) having a solid content of 25 wt% adjusted to a temperature of 0 ° C., After washing with ethanol, it was dried at 50 ° C. for 20 minutes.
Then, a conductive paste was applied and a cathode lead was attached.

As shown in Table 1, the solid electrolytic capacitor thus obtained has a resistance of 98.
It had a capacitance of 8 μF and had an equivalent series resistance (ESR) of 254 mΩ at 100 kHz. These electrical characteristics are referred to as the electrical characteristics before the moist heat resistance test.

This solid electrolytic capacitor has a temperature of 8
After being left for 24 hours in a thermo-hygrostat at 5 ° C. and a relative humidity of 85%, as shown in Table 1, at 120 Hz, 95.
It had a capacitance of 7 μF and had an equivalent series resistance (ESR) of 263 mΩ at 100 kHz. These electrical characteristics are called electrical characteristics after the moist heat resistance test. The solid electrolytic capacitor according to the present invention thus has excellent resistance to moisture and heat.

Example 2 A solid electrolytic capacitor was prepared in the same manner as in Example 1 except that m-carboxy-p-phenolsulfonic acid novolac resin was used as the doping liquid instead of p-phenolsulfonic acid novolac resin aqueous solution. Was produced. Table 1 shows the electrical characteristics of the solid electrolytic capacitor before and after the moisture heat resistance test.

Comparative Example 1 A solid electrolytic capacitor was produced in the same manner as in Example 1 except that a 20 wt% polyvinyl sulfonic acid aqueous solution was used as the doping liquid. Table 1 shows the electrical characteristics of the solid electrolytic capacitor before and after the moisture heat resistance test.

Comparative Example 2 A solid electrolytic capacitor was produced in the same manner as in Example 1 except that a 20% by weight polystyrene sulfonic acid aqueous solution was used as the doping liquid. Table 1 shows the electrical characteristics of the solid electrolytic capacitor before and after the moisture heat resistance test.

Comparative Example 3 A solid electrolytic capacitor was produced in the same manner as in Example 1 except that a 25 wt% p-toluenesulfonic acid aqueous solution was used as the doping liquid. Table 1 shows the electrical characteristics of the solid electrolytic capacitor before and after the moisture heat resistance test.

[0070]

[Table 1]

[0071]

As described above, the solid electrolytic capacitor according to the present invention comprises a conductive polyaniline composition having a dielectric film on a film-forming metal and polyaniline doped with a phenolsulfonic acid novolac resin. The membrane is used as a solid electrolyte, and the membrane made of the above conductive polyaniline composition is excellent in water resistance and wet heat resistance, and also excellent in heat resistance.
Therefore, the solid electrolytic capacitor according to the present invention is excellent in durability and reliability, is also excellent in adhesion between the solid electrolyte and the dielectric film, has a small impedance in a high frequency region, and has a large capacitance.

Further, according to the method of the present invention, unlike the conventional method of forming a conductive polymer composition on a dielectric film by chemical oxidative polymerization of a monomer, a polyaniline solution is applied and then doped. As a result, the solid electrolyte composed of the conductive polymer composition can be easily formed, and the productivity is excellent.

[Brief description of drawings]

FIG. 1 is a graph showing a change in electric conductivity with time when a conductive polyaniline film having a p-phenolsulfonic acid novolac resin as a dopant is immersed in distilled water according to the present invention in comparison with a polyaniline film having a polyvinylsulfonic acid as a dopant. Is a graph shown.

FIG. 2 is a polyaniline film having a polyvinyl sulfonic acid as a dopant, showing the change with time of the electric conductivity when a conductive polyaniline film having a p-phenol sulfonic acid novolac resin as a dopant is placed in an atmosphere of 125 ° C. according to the present invention. It is a graph shown in comparison with.

Claims (7)

[Claims] 1. A film having a dielectric film on a film-forming metal and comprising a conductive polyaniline composition obtained by doping polyaniline with a phenol sulfonic acid novolac resin, as a solid electrolyte on the dielectric film. Solid electrolytic capacitor characterized by. 2. Polyaniline is represented by the general formula (I): (In the formula, m and n each represent a mole fraction of the quinonediimine structural unit and the phenylenediamine structural unit in the repeating unit, and 0 <m <1, 0 <n <1, and m + n = 1). Consisting of repeating units, N-methyl-
The intrinsic viscosity [η] measured at 30 ° C in 2-pyrrolidone is
The solid electrolytic capacitor according to claim 1, which has a density of 0.40 dL / g or more. 3. A phenolsulfonic acid novolak resin represented by the general formula (II): (In the formula, R represents an alkyl group, an alkoxyl group, a hydroxyl group,
Indicates a carboxyl group or an amino group. ) The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor is represented by 4. A dielectric film is formed on a film-forming metal, a polyaniline film is formed on the dielectric film, and then the polyaniline film is brought into contact with an aqueous solution of a phenol sulfonic acid novolak resin to form the phenol. A method for producing a solid electrolytic capacitor, which comprises doping the polyaniline with a sulfonic acid novolac resin. 5. The method for producing a solid electrolytic capacitor according to claim 4, wherein a polyaniline solution is applied on the dielectric film and dried to form the polyaniline film on the dielectric film. 6. Polyaniline is represented by the general formula (I): (In the formula, m and n each represent a mole fraction of the quinonediimine structural unit and the phenylenediamine structural unit in the repeating unit, and 0 <m <1, 0 <n <1, and m + n = 1). Consisting of repeating units, N-methyl-
The intrinsic viscosity [η] measured at 30 ° C in 2-pyrrolidone is
It is 0.40 dL / g or more, The manufacturing method of the solid electrolytic capacitor of Claim 4 or 5. 7. A phenolsulfonic acid novolak resin represented by the general formula (II): (In the formula, R represents an alkyl group, an alkoxyl group, a hydroxyl group,
Indicates a carboxyl group or an amino group. The solid electrolytic capacitor manufacturing method according to claim 4, wherein the solid electrolytic capacitor is represented by