JP2001189242A - Solid electrolytic capacitor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large capacitance solid electrolytic capacitor by enhancing the usable rate of electrostatic capacitance. SOLUTION: By using a capacitor element 10, formed by winding an anode foil 1 with a dielectric oxide film and a cathode foil 2 having a dielectric oxide film with the withstand voltage of 0.8-10 V. with a separator 3a located in-between, and a solid electrolyte of conductive polymer provided between the anode foil 1 and the cathode foil 2 of the capacitor element 10, a large capacitance solid electrolytic capacitor is obtained with small impedance in a high-frequency region and high usable rate of electrostatic capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid electrolytic capacitor, and more particularly to a wound solid electrolytic capacitor using a conductive polymer as a solid electrolyte and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the increase in the frequency of electronic equipment, there has been a demand for a large-capacity electrolytic capacitor which is more excellent in impedance characteristics in a high-frequency region than in the past as an electronic component. Recently, in order to reduce the impedance in the high frequency region, a solid electrolytic capacitor using a solid polymer such as a conductive polymer having high electric conductivity or a tetracyano methane dimethane complex (hereinafter referred to as TCNQ) has been studied. In addition, in order to meet the demand for large capacity, it is easier to structurally increase the capacity compared to the case of laminating electrode foils. Conductive polymer or TCN with aluminum foil cathode foil wound around a separator)
Solid electrolytic capacitors using the solid electrolyte of Q have been commercialized.

In the solid electrolytic capacitor having the above-mentioned wound structure, it is essential to interpose a separator in order to avoid contact between the anode foil and the cathode foil. In a conventional electrolytic capacitor using an electrolytic solution as an electrolyte, so-called electrolytic paper made of manila hemp or kraft paper is used.However, as a separator of a wound solid electrolytic capacitor using a solid electrolyte, the above electrolytic paper is used. It is known to use a material obtained by carbonizing this electrolytic paper by a method such as heating after winding a capacitor element (hereinafter referred to as carbonized paper), a glass fiber nonwoven fabric, a melt blown nonwoven fabric made of polypropylene, or the like.

[0004] As the solid electrolyte, polypyrrole and polyethylenedioxythiophene formed by chemically oxidizing and polymerizing pyrrole and ethylenedioxythiophene with an appropriate oxidizing agent are known.

[0005] TCNQ solid electrolytes are also used in wound aluminum electrolytic capacitors.
NQ is heated to a temperature higher than its melting point,
Q (the component that contributes to conductivity is substantially 100%)
Is impregnated in a capacitor element and cooled to form a solid electrolyte of TCNQ between the anode foil and the cathode foil of the capacitor element. At this time, there is a cathode foil having a dielectric oxide film of about 2 to 5 V on the cathode foil for the purpose of preventing application of a reverse voltage to the capacitor.

[0006]

However, in the above-mentioned wound solid electrolytic capacitor, the rate of drawing out the capacitance from the cathode foil side is much lower than that of the anode foil side. Even if the capacitance extraction rate is sufficient, the capacitance of the wound capacitor is composed of the series combined capacitance of the capacitance drawn from the anode foil side and the capacitance drawn from the cathode foil side. In addition, the capacitance extraction ratio of the capacitor itself usually reaches only about 40 to 50%, and as a result, there is a problem that the size per capacitance is larger than that of a capacitor using an electrolyte as an electrolyte.

As a countermeasure, for example, a polymerization solution containing a polymerizable monomer such as ethylenedioxythiophene, an oxidizing agent such as ferric p-toluenesulfonate, and a solvent (an alcohol such as water or n-butanol) is used. It is necessary to impregnate the capacitor element and form a large amount near the surface of the electrode foil by polymerization. In order to realize this, it is desirable to adopt a configuration using a separator having a large liquid retention amount and a density as low as possible. However, if the density of the separator is reduced, the short-circuit rate increases, so this measure is extremely difficult.

In particular, in the case of a solid electrolytic capacitor having a rated voltage of 16 V or more, when the density of the separator is increased to reduce the short-circuit rate and to improve the withstand voltage, the bulk density of the separator increases. Has a problem that the amount of the polymerization solution that can be present in the vicinity of the polymer cannot be sufficiently ensured, and a sufficient amount of the conductive polymer solid electrolyte to obtain the capacitance cannot be obtained.

On the other hand, the carbonized paper used for the separator of the wound-type solid electrolytic capacitor requires heating exceeding 250 ° C. to carbonize the electrolytic paper, and this heating damages the dielectric oxide film. There is a problem that the leakage current becomes large, and the short-circuit occurrence rate becomes high even if it is repaired by aging. In addition, the plating layer (for example, tin / lead layer) of the lead wire of the electrolytic capacitor is oxidized by this heating, and the solder wettability in the lead wire portion of the completed product is significantly reduced with a normal plated wire.
There was a problem that an expensive silver-plated lead wire having strong oxidation resistance had to be used.

[0010] Further, those using a glass fiber nonwoven fabric are:
There is a large problem in the working environment due to the scattering of needle-like glass fibers around when cutting or winding, and the strength at the time of bending due to winding is fragile, and the product is easily short-circuited. The method using a non-woven fabric containing a resin as a main component by the method has a low tensile strength compared to electrolytic paper, so the separator tends to break when winding the capacitor element, and the short-circuiting rate during aging is high.
It is said that it is difficult to hold the conductive polymer on the separator due to the effect of the adhesive component used when the resin fibers are bonded and short-circuited, and it is difficult to manufacture a solid electrolytic capacitor having low impedance in a high frequency region. There were challenges.

Further, polypyrrole and polyethylenedioxythiophene obtained by chemically oxidizing and polymerizing pyrrole and ethylenedioxythiophene with an appropriate oxidizing agent are known as conductive polymers used for the solid electrolyte. Since it is difficult to hold paper or glass fiber non-woven fabric, the impedance increases due to the separation of the conductive polymer from the separator due to thermal stress, etc., and the extraction rate of the capacitance is poor. There is a problem that the size per capacity is larger than that of the capacitor in such a case.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a large-capacity solid electrolytic capacitor having a low impedance characteristic in a high-frequency region and a high capacitance extraction ratio, and a method of manufacturing the same. is there.

[0013]

According to a first aspect of the present invention, there is provided an anode foil having a dielectric oxide film formed thereon and a dielectric foil having a withstand voltage of 0.8 to 10V. A capacitor element formed by winding a cathode foil having a body oxide film formed thereon through a separator, and a configuration made of a conductive polymer solid electrolyte provided between an anode foil and a cathode foil of the capacitor element With this configuration, the dielectric oxide film formed on the cathode foil improves the wettability with a polymerization solution (more specifically, a solution containing a large amount of a hydrogen-bonding solvent such as water or alcohol). So you can
Even if the amount of the polymerization solution present in the vicinity of the cathode foil is the same as before, the coating efficiency of the generated conductive polymer on the cathode foil with the solid electrolyte is significantly improved, and the capacitance extraction rate is increased. As a result, the combined series capacitance with the capacitance drawn from the anode foil also increases, and has the effect that a large-capacity solid electrolytic capacitor can be obtained.

When the withstand voltage of the cathode foil exceeds 10 V, the substantial capacity of the cathode foil itself per unit area (the capacitance of the electrode foil itself measured in a solution) decreases, so that a large capacity is required. It is often rather difficult to construct a capacitor. On the other hand, when the voltage is 0.8 V or less, it is difficult to form a uniform oxide film, so that the wettability with the polymerization solution is deteriorated, which does not lead to an improvement in the capacitance extraction rate. Therefore, the preferred range of the withstand voltage of the oxide film of the cathode foil is in the range of 0.8 to 10 V, more preferably 1.0 V
It is in the range of ~ 5V.

Although the cathode foil used in the conventional aluminum electrolytic capacitor has a withstand voltage of about 0.2 V to 0.5 V, these are made of a thermal oxide film or a natural oxide film and have a non-uniformity. It is not suitable for the purpose of the present invention because it contains hydrates in the film.

As the dielectric oxide film of the present invention, an oxide film formed by an anodic oxidation method is suitable. The dielectric oxide film formed by this anodic oxidation method is dense and uniform, so that the wettability of the cathode foil surface is improved and the capacitance extraction rate is improved. The impedance can be reduced.

According to a second aspect of the present invention, in the first aspect of the invention, the separator is made of a non-woven fabric mainly composed of a resin, and the third aspect of the present invention is the second aspect of the present invention. The non-woven fabric mainly composed of resin is made of a non-woven fabric containing polyester. Further, the invention according to claim 4 is characterized in that the non-woven fabric mainly composed of resin is spunbonded in the invention according to claim 2. It is made of a non-woven fabric containing polyethylene terephthalate manufactured by the method,
Since the amount of the polymerization solution impregnated in the separator can be more impregnated than that of the other separator materials, the effect of increasing the capacitance extraction rate can be obtained.

The reason is that the polymerizable heterocyclic monomer having a five-membered ring represented by thiophene or ethylenedioxythiophene has high compatibility with the polyester fiber (because the solubility parameters are close to each other). ), Both sides are familiar. polyethylene·
Polyolefins such as polypropylene, polyphenylene sulfide, vinylon, nonwoven fabrics containing a resin with high compatibility with a polymerization solution such as rayon (compared with glass fiber), although effective, polyester,
In particular, polyethylene terephthalate, polybutylene terephthalate and mixed non-woven fabrics containing these polyesters are suitable for the above-mentioned viewpoints of compatibility and heat resistance (melting point of resin).
It is more suitable than the viewpoint.

The nonwoven fabric produced by the spunbond method has a longer fiber length than that of the nonwoven fabric produced by the melt blow method or the tow opening method. Becomes stronger, the frequency of separator breakage when winding the capacitor element decreases,
It is also preferable because the occurrence rate of short circuit is reduced. Most preferably, it is a non-woven fabric containing polyethylene terephthalate produced by a spunbond method, which is made of a resin containing polyethylene terephthalate among the resins and a polyethylenedioxythiophene which is a solid electrolyte of a conductive polymer. Since the adhesion / adhesion is extremely strong, it also has the effect that the impedance in the high frequency region can be further reduced as compared with the combination of another resin separator / conductive polymer solid electrolyte.

According to a fifth aspect of the present invention, in the second aspect, the nonwoven fabric mainly composed of a resin comprises a nonwoven fabric containing polyethylene terephthalate and / or polybutylene terephthalate manufactured by a wet method. With these configurations, since the amount of the polymerization solution impregnated in the separator can be more impregnated than other separator materials, the effect of increasing the capacitance extraction rate can be obtained. .

Further, the nonwoven fabric containing polyethylene terephthalate and / or polybutylene terephthalate produced by the wet method is different from the nonwoven fabric obtained by the wet method using other resins as a main component, and compared with the same thickness and the same weight. Since the tensile strength of the fiber itself can be increased, the frequency of breakage of the separator during winding of the capacitor element can be reduced, and the short-circuit occurrence rate can be reduced.

As the nonwoven fabric containing polyethylene terephthalate produced by the wet method, a polyethylene terephthalate resin or a polybutylene terephthalate resin is used, or a polyethylene terephthalate resin and / or a polybutylene terephthalate resin and a vinylon-based resin are used. Fiber, nylon fiber, rayon fiber, polyethylene fiber, polypropylene fiber, trimethylpentene fiber, polyphenylene sulfide fiber, celluloid (or nitrated cellulose) fiber,
At least one of celluloses represented by Manila hemp fiber
A mixed nonwoven fabric obtained by a wet method with seeds can be used.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the separator is formed of a nonwoven fabric having a different density in a thickness direction, and the low density side of the nonwoven fabric is arranged to face the cathode foil side. With this configuration, a sufficient amount of the polymer solution is present in the vicinity of the cathode foil to form a solid electrolyte of a conductive polymer necessary for extracting capacitance from the cathode foil. In addition to being able to prevent the anode-side spark caused by the occurrence of a short circuit, it is also possible to secure sufficient isolation between the electrodes (higher separator density side) at the same time.
Although it has a large capacity, it has an effect that a short circuit can be hardly generated even during aging during manufacturing.

The method of adjusting the density in the thickness direction of the separator includes a method of heat welding two nonwoven fabrics having different densities, a method of pressure bonding, a method of using both heat welding and pressure bonding, and a method of preparing a nonwoven fabric prepared in advance. It is desirable that resin fibers are deposited on the surface of the substrate in such a manner that the resin fibers are softened or semi-melted by adjusting the temperature so that the density differs in the thickness direction, and then the resin fibers are joined. The method of bonding and adjusting the two separators with an adhesive or the like is not preferable because the impedance performance when a capacitor is formed is significantly reduced.

According to a seventh aspect of the present invention, the anode foil on which the dielectric oxide film is formed and the cathode foil on which the dielectric oxide film having a withstand voltage of 0.8 to 10 V is formed face each other. In the meantime, a conductive polymer solid electrolyte is provided between them.The presence of the dielectric oxide film on the cathode foil improves the wettability with the polymerization solution, and the polymerization existing near the cathode foil. Even if the amount of the solution is the same as the conventional one, the coating property of the generated conductive polymer solid electrolyte on the cathode foil is remarkably improved, so that the effect of increasing the capacitance extraction rate can be obtained.

According to the present invention, the anode foil on which the dielectric oxide film is formed and the cathode foil on which the dielectric oxide film having a withstand voltage of 0.8 to 10 V is formed mainly of resin. The capacitor element is formed by winding through a separator made of a nonwoven fabric, and the capacitor element is individually impregnated with a solution containing ethylenedioxythiophene or a derivative thereof and an oxidizing agent solution containing sulfonates or ethylenedioxythiophene. A method in which a solid electrolyte containing polyethylene dioxythiophene is formed between an anode foil and a cathode foil by impregnating a mixed solution containing oxythiophene or its derivative and an oxidizing agent containing sulfonates. This has the effect that a large capacity solid electrolytic capacitor having a high capacitance extraction rate can be manufactured.

According to these inventions, it is possible to obtain a large-capacity solid electrolytic capacitor having a low impedance characteristic in a high frequency region and a high capacitance extraction ratio.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partial sectional perspective view showing the structure of a solid electrolytic capacitor according to the present invention. In FIG. 1, a dielectric oxide film (not shown) is formed by anodizing after roughening the surface by etching. ), And a cathode foil 2 on which a dielectric oxide film (not shown) is formed by etching the aluminum foil to form a dielectric oxide film (not shown) through an separator 3a. A capacitor element 10 is manufactured, and a solid electrolyte (not shown) of a conductive polymer is formed between the anode foil 1 and the cathode foil 2 to form the capacitor element 10.

The capacitor element 10 is housed in a cylindrical aluminum case 8 with a bottom, and the open end of the aluminum case 8 is led out of each of the anode foil 1 and the cathode foil 2 by a rubber sealing material 7. The anode lead 5 and the cathode lead 6 are sealed so as to penetrate the sealing material 7.

FIGS. 2 (a) and 2 (b) are conceptual diagrams in which main parts of the capacitor element are enlarged. FIG. 1A shows an anode foil 1 made of an aluminum foil having a dielectric oxide film 9a formed by anodic oxidation after roughening the surface by etching and a dielectric having a withstand voltage of 0.8 to 10V. A separator 3a is interposed between the anode foil 1 and the cathode foil 2 having the oxide film 9b formed by the anodic oxidation method, and the conductive polymer solid electrolyte 4 is formed between the anode foil 1 and the cathode foil 2. 10.

FIG. 2B shows an anode foil 1 made of an aluminum foil having a dielectric oxide film 9a formed by oxidation after roughening the surface by etching.
The anode foil 1 and the cathode foil 2 are separated by interposing a separator 3b having a different density in the thickness direction between the anode foil 2 and the cathode foil 2 on which a dielectric oxide film 9b having a withstand voltage of 0.8 to 10 V is formed by anodic oxidation. The capacitor element 10 is formed by forming a solid electrolyte 4 of a conductive polymer between the first and second electrodes. At this time, the low-density side of the separator 3b is arranged to face the cathode foil 2 side.

Next, specific examples of the present invention will be described, but the present invention is not limited to these examples.

(Example 1) An anode foil in which a dielectric oxide film was formed by anodic oxidation after roughening the surface of an aluminum foil by etching treatment and a dielectric oxide film having a withstand voltage of 0.8 V were anodized. Made of a nonwoven fabric made of polyethylene terephthalate obtained by a spunbonding method between a cathode foil formed by a sputtering method and a separator having a thickness of 50 μm.
m, weighing 25 g / m ² , and density 0.5 g / cm ³ ) to obtain a wound capacitor element. This capacitor element contains ammonium adipate
The capacitance at a frequency of 120 Hz when impregnated with a 0% by weight ethylene glycol solution was 200 μF.

Subsequently, the capacitor element was replaced with polyethylene dioxythiophene polystyrene sulfonic acid 1.0%.
After being immersed in an aqueous solution and pulled up, a drying treatment was performed at 150 ° C. for 5 minutes to form a layer of polyethylene dioxythiophene polystyrene sulfonic acid on the dielectric oxide films of the anode foil and the cathode foil and on the separator fibers.

Subsequently, a solution containing 1 part of ethylenedioxythiophene as a heterocyclic monomer, 2 parts of ferric p-toluenesulfonate as an oxidizing agent, and 4 parts of n-butanol as a polymerization solvent was prepared. Then, the substrate was left at 85 ° C. for 60 minutes to form polyethylene dioxythiophene, a chemically polymerizable conductive polymer, between the anode foil and the cathode foil.

Subsequently, the capacitor element was washed and dried, and then a resin-vulcanized butyl rubber sealing material (consisting of 30 parts of butyl rubber polymer, 20 parts of carbon, and 50 parts of an inorganic filler, sealing body hardness: 70 IRHD [International rubber hardness] unit])
After sealing in the aluminum outer case, the opening is sealed by a curling process, and both lead terminals respectively derived from the anode foil and the cathode foil are passed through a polyphenylene sulfide seat plate, and the lead wires are flattened. Then, a surface-mount type solid electrolytic capacitor was manufactured (size: diameter 10 mm × height 10 mm, rated voltage 16 V).

(Example 2)
Instead of a cathode foil having a dielectric oxide film having a withstand voltage of 8 V formed by an anodizing method, 0.5 V, 1 V, 5 V,
Surface mount type solid electrolytic capacitors were produced in the same manner as in Example 1 except that a cathode foil in which dielectric oxide films having different withstand voltages of 7 V, 10 V and 12 V were formed by anodic oxidation was used.

Example 3 In Example 1, a nonwoven fabric (thickness 50 μm, weighing 25 g / m ² , density 0.5 g / cm ³ ) made of polyethylene terephthalate obtained by a wet method was used as the separator. Produced a surface mount type solid electrolytic capacitor in the same manner as in Example 1.

Example 4 In Example 1, a non-woven fabric made of polybutylene terephthalate (thickness 50 μm, weighed 25 g / m ² , density 0.5 g / cm ³ ) obtained by a wet method was used as the separator. Except for the above, a surface mount type solid electrolytic capacitor was produced in the same manner as in Example 1.

Example 5 In Example 1, a nonwoven fabric made of polyethylene terephthalate (thickness: 50 μm, inner thickness: 30 μm, density: 0.8 g) was formed on the separator by a spunbond method having different densities in the thickness direction. / C
m ³ , and the remaining 20 μm continuous to this have a density of 0.2 g /
cm ³ ), and a surface-mounted solid electrolytic capacitor was produced in the same manner as in Example 1 except that the low-density surface was wound facing the cathode foil side.

Example 6 In Example 1, a mixed nonwoven fabric separator (thickness: 50 μm, weighed: 25 g / m ² , density: 0.5 g / cm ³ ) containing rayon and glass fiber was used as the separator. Except for the above, a surface mount type solid electrolytic capacitor was produced in the same manner as in Example 1.

(Example 7) Except that a nonwoven fabric made of polypropylene (thickness: 50 μm, weighed: 25 g / m ² , density: 0.5 g / cm ³ ) obtained by a spun bond method was used as the separator in Example 1 described above. Produced a surface mount type solid electrolytic capacitor in the same manner as in Example 1.

Example 8 Example 1 was repeated except that 1 part of pyrrole was used as the heterocyclic monomer, 2 parts of ammonium persulfate was used as the oxidizing agent, and a mixed solvent of 1 part of methanol and 3 parts of water was used as the polymerization solvent. A surface mount type solid electrolytic capacitor was manufactured in the same manner as in Example 1.

(Comparative example)
Instead of a cathode foil having a dielectric oxide film having a withstand voltage of V, a cathode foil having no dielectric oxide film formed thereon (as a result of withstand voltage measurement, the withstand voltage of the natural oxide film of this cathode foil was 0.3 V Except that) was used in the same manner as in Example 1 to produce a surface-mount type solid electrolytic capacitor.

Examples 1 to 3 of the present invention produced as described above
The results of comparing the capacitance (measurement frequency 120 Hz), impedance (measurement frequency 100 kHz), leakage current (two minutes after application of the rated voltage 16 V), and the number of short circuits during aging for the solid electrolytic capacitors of Comparative Example 8 and Comparative Example Are shown in (Table 1).

[0047]

[Table 1]

The number of tests was 50 in each case.
Capacitance, impedance and leakage current are 50
The average value is shown for items excluding short products during aging.

As is clear from Table 1, the solid electrolytic capacitors of Examples 1 and 2 have a dielectric oxide film having a withstand voltage of 10 V or less on the cathode foil, as compared with the solid electrolytic capacitors of Comparative Examples. The capacitance extraction ratio due to the formation was high, and the impedance characteristics were also excellent.

In the second embodiment, when the withstand voltage of the dielectric oxide film of the cathode foil is 10 V or more, the capacitance extraction ratio is low and the impedance characteristics are inferior. In addition, since the solid electrolytic capacitor of 0.5 V or less comes close to the result of the comparative example, the withstand voltage of the dielectric oxide film of the cathode foil is preferably 0.8 V or more and 10 V or less.

The solid electrolytic capacitors of Examples 3 and 4 were replaced with a separator made of a nonwoven fabric made of polyethylene terephthalate manufactured by a spunbond method.
The separator using a nonwoven fabric made of polyethylene terephthalate and polybutylene terephthalate manufactured by a wet method is used, and the same capacitance and impedance characteristics as those of the solid electrolytic capacitor of Example 1 can be obtained.

In the solid electrolytic capacitor of Example 5, the anode foil and the cathode foil were wound with separators having different densities in the thickness direction interposed therebetween, with the low density side of the separator facing the cathode foil side. Therefore, the capacitance is larger than the capacitance of the solid electrolytic capacitor of Example 1 wound around a separator having a uniform thickness, and the impedance performance is also excellent.

In the comparison between Example 1 and Examples 6 and 7, it was found that the separator was made of a nonwoven fabric containing a resin.
Examples 6 and 7 are slightly inferior to Example 1 in terms of capacitance, though they have a common configuration in that a dielectric oxide film having a withstand voltage is formed on the cathode foil. The reason for this is that in Example 1, polyethylene terephthalate, which is one of the polyester resins having the highest adhesion to polyethylene dioxythiophene, was used for the separator material, and rayon or polypropylene was used for the separator material. The effects of the present invention can be sufficiently brought out more than the configurations of the sixth and seventh embodiments. Further, in Example 6 using the mixed separator of rayon and glass fiber, the leakage current value tends to be large due to the influence of the glass fiber, and short-circuiting occurs although the number is short.

The solid electrolytic capacitor of Example 8 uses pyrrole instead of the ethylenedioxythiophene used in Example 1, but the same characteristics as in Example 1 could be obtained.

[0055]

As described above, the solid electrolytic capacitor according to the present invention is characterized in that the anode foil having the dielectric oxide film formed thereon is
A capacitor element formed by winding a cathode foil on which a dielectric oxide film having a withstand voltage of 0 V is formed via a separator,
By adopting a configuration comprising a solid electrolyte of a conductive polymer provided between the anode foil and the cathode foil of this capacitor element, the wettability between the dielectric oxide film formed on the cathode foil and the polymerization solution is improved. To obtain a large-capacity solid electrolytic capacitor with extremely high coverage of the conductive polymer solid electrolyte generated in the vicinity of the cathode foil, low impedance characteristics in the high-frequency region, and a high capacitance extraction rate. And its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view showing a configuration of a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2A is a conceptual diagram of an enlarged main part of the capacitor element of the first embodiment. FIG. 2B is a conceptual diagram of an enlarged main part of the capacitor element of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode foil 2 Cathode foil 3a Separator 3b Separator with different density in thickness direction 4 Conductive polymer solid electrolyte 5 Anode lead 6 Cathode lead 7 Sealing material 8 Aluminum case 9a, 9b Dielectric oxide film 10 Capacitor element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01G 9/02 301 H01G 9/05 G 9/028 9/02 331E 9/00 9/24 C

Claims (8)

[Claims] A capacitor element comprising an anode foil on which a dielectric oxide film is formed and a cathode foil on which a dielectric oxide film having a withstand voltage of 0.8 to 10 V is formed via a separator. A solid electrolytic capacitor comprising a conductive polymer solid electrolyte provided between an anode foil and a cathode foil of a capacitor element. 2. The solid electrolytic capacitor according to claim 1, wherein the separator is made of a nonwoven fabric mainly composed of a resin. 3. The solid electrolytic capacitor according to claim 2, wherein the non-woven fabric mainly composed of a resin is a non-woven fabric containing polyester. 4. The solid electrolytic capacitor according to claim 2, wherein the non-woven fabric mainly composed of a resin is a non-woven fabric containing polyethylene terephthalate manufactured by a spun bond method. 5. The solid electrolytic capacitor according to claim 2, wherein the nonwoven fabric mainly composed of a resin is a nonwoven fabric containing polyethylene terephthalate and / or polybutylene terephthalate manufactured by a wet method. 6. The solid electrolytic capacitor according to claim 1, wherein the separator is a nonwoven fabric having a different density in the thickness direction, and the low density side of the nonwoven fabric is wound so as to face the cathode foil side. 7. An anode foil having a dielectric oxide film formed thereon and a cathode foil having a dielectric oxide film having a withstand voltage of 0.8 to 10 V are installed so as to face each other. A solid electrolytic capacitor with a molecular solid electrolyte. 8. An anode foil on which a dielectric oxide film is formed and a cathode foil on which a dielectric oxide film having a withstand voltage of 0.8 to 10 V are formed via a separator made of a nonwoven fabric mainly composed of a resin. The capacitor element is formed by winding, and the capacitor element is individually impregnated with a solution containing ethylenedioxythiophene or a derivative thereof and an oxidizing agent solution containing sulfonates, or is mixed with ethylenedioxythiophene or a derivative thereof and sulfone. A method for producing a solid electrolytic capacitor, wherein a solid electrolyte containing polyethylenedioxythiophene is formed between an anode foil and a cathode foil by impregnating a mixed solution containing an oxidizing agent containing an acid salt.