Electrolytic capacitor and method for manufacturing the same
The electrolytic capacitor with a conductive polymer and surfactant first layer, and PEDOT derivative second layer, addresses the challenge of high ESR and LC variation, achieving low ESR and stable LC characteristics.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NICHICON CORP
- Filing Date
- 2025-01-07
- Publication Date
- 2026-07-17
AI Technical Summary
Existing electrolytic capacitors face challenges in achieving both low equivalent series resistance (ESR) and low leakage current (LC) variation, with previous methods either increasing ESR or LC, or failing to maintain voltage withstand capability.
The electrolytic capacitor is designed with a first solid electrolyte layer containing a conductive polymer and surfactant adjacent to the dielectric oxide film, and a second solid electrolyte layer using a specific PEDOT derivative, which together provide improved ESR and reduced LC variation.
The capacitor achieves low ESR and low LC variation, maintaining excellent electrical conductivity and voltage withstand capability.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to an electrolytic capacitor and a method for manufacturing the same. More specifically, the present invention relates to an electrolytic capacitor with excellent equivalent series resistance (ESR) characteristics and leakage current (LC) characteristics and a method for manufacturing the same. [Background technology]
[0002] Electrolytic capacitors are essential electronic components for the development of electronic devices, and therefore, various improvements have been made to enhance their characteristics.
[0003] For example, Patent Document 1 discloses a solid electrolytic capacitor characterized in that, for the purpose of improving withstand voltage and suppressing the increase in ESR, the solid electrolyte cathode layer consists of a first solid electrolyte layer and a second solid electrolyte layer, and the electrical conductivity of the first solid electrolyte layer immediately adjacent to the dielectric film is controlled to be lower than that of the second solid electrolyte layer located above it.
[0004] More specifically, Patent Document 1 describes a method in which a conductive polymer film is formed on a dielectric film, and then the electrical conductivity of the first solid electrolyte layer immediately adjacent to the dielectric film is increased to 2.7 × 10⁻⁶ by contact with an oxidizing agent or reducing agent solution, heat treatment, or cathode polarization. -7 ~7.6×10 -5 It is disclosed that by controlling the voltage resistance to S / cm and forming a second solid electrolyte layer with multiple layers on top of it by chemical polymerization and electrolytic polymerization, the dielectric strength can be improved and the increase in ESR can be suppressed. The electrical conductivity of the first solid electrolyte layer is set to 10 -10 ~10 -2 As stated, controlling the voltage resistance within the S / cm range improves the withstand voltage and suppresses the rise in ESR. However, in methods of forming a solid electrolyte layer inside a capacitor element by chemical polymerization and electrolytic polymerization, the aluminum oxide film has poor repairability due to the presence of unreacted materials or residues such as iron, and film defects are exposed due to hydrogen embrittlement caused by the polymerization reaction. Therefore, in order to maintain the withstand voltage, the electrical conductivity of the first solid electrolyte layer is set to 10. -2 It needed to be lower than S / cm.
[0005] On the other hand, in addition to methods for producing conductive polymer layers (solid electrolyte layers) by chemical polymerization and electrolytic polymerization of monomers, a method has also become common in which a conductive polymer layer is formed inside a capacitor element by impregnating and drying the element in a dispersion of conductive polymer (for example, polyethylenedioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) dispersed in water). This method has the advantage of improving voltage resistance because, unlike chemical polymerization and electrolytic polymerization, no excess residue remains inside the capacitor element since the capacitor element is impregnated in a dispersion of conductive polymer that has been polymerized and purified in advance. Therefore, with this method, the electrical conductivity of the first solid electrolyte layer can be increased to 10 -2 Even when the voltage is higher than S / cm, the voltage withstand capability can be maintained. One method for increasing the electrical conductivity of the first solid electrolyte layer is to add ethylene glycol or the like to a conductive polymer dispersion. This method has been shown to dramatically improve the electrical conductivity of the conductive polymer layer, and along with the improvement in electrical conductivity, the ESR value of the capacitor can also be reduced.
[0006] In addition, a self-doped conductive polymer solution has been proposed as an alternative to conductive polymer dispersions. Since the self-doped conductive polymer is dissolved in the solvent rather than dispersed as particulate matter, it can impregnate even the fine pits of the electrode foil, resulting in excellent penetration and improved capacitor characteristics.
[0007] However, if the electrical conductivity of the first solid electrolyte layer is 10 -2 Even when the ESR is reduced by increasing the S / cm ratio, and the voltage withstand capability is maintained by using a self-doped conductive polymer and adding ethylene glycol, the problem remains that the LC of the capacitor increases, and its variation becomes large. [Prior art documents] [Patent Documents]
[0008] [Patent Document 1] Japanese Patent Publication No. 2003-173933 [Overview of the Initiative] [Problems that the invention aims to solve]
[0009] The present invention aims to solve the aforementioned problems and provide an electrolytic capacitor with excellent ESR characteristics and LC characteristics. [Means for solving the problem]
[0010] As a result of repeated studies to solve the above problems, the inventors of the present invention have found that in an electrolytic capacitor having multiple conductive polymer layers on a dielectric oxide film (anodic oxide film), by forming a solid electrolyte layer containing a surfactant and having an electrical conductivity of 0.01 S / cm or more as the first solid electrolyte layer immediately adjacent to the dielectric oxide film, and then forming a second solid electrolyte layer containing a self-doped conductive polymer represented by a specific formula, both ESR and LC variation can be improved, and the present invention has been completed.
[0011] The electrolytic capacitor of the present invention is An electrolytic capacitor having a capacitor element in which an anode foil having a dielectric oxide film and a cathode foil are wound with a separator in between, The capacitor element has a first solid electrolyte layer and a second solid electrolyte layer on a dielectric oxide film. The first solid electrolyte layer is a layer immediately adjacent to the dielectric oxide film, and contains a conductive polymer and a surfactant, and has an electrical conductivity of 0.01 S / cm or higher. The second solid electrolyte layer contains a polyethylenedioxythiophene (PEDOT) derivative represented by the following formula I. TIFF2026119559000001.tif31169 (in the formula, x is an integer greater than or equal to 2, m is an integer between 1 and 10. n is either 0 or 1. M is a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. R is a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms with a substituent, or a fluorine atom) characterized by.
[0012] Since the electric conductivity of the first solid electrolyte layer of the electrolytic capacitor is 0.01 S / cm or more, the ESR can be reduced. Conventionally, when the electric conductivity of the first solid electrolyte layer is 0.01 S / cm or more, the variation in LC increases. However, when the first solid electrolyte layer contains a surfactant and the second solid electrolyte layer contains the PEDOT derivative of formula I, even if the electric conductivity of the first solid electrolyte layer is 0.01 S / cm or more, the variation in LC can be kept low.
[0013] Preferable examples of the first solid electrolyte layer include a solid electrolyte layer containing polyaniline or a derivative thereof and an acetylene-based surfactant. Examples of preferable acetylene-based surfactants include 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, or an ethoxylated product thereof.
[0014] The electrolytic capacitor preparing a capacitor element in which an anode foil having a dielectric oxide film and a cathode foil are wound through a separator; <000008><0>impregnating the capacitor element with a first conductive polymer liquid containing a conductive polymer and a surfactant to form a first solid electrolyte layer having an electric conductivity of 0.01 S / cm or more; then, impregnating the capacitor element with a second conductive polymer liquid containing the PEDOT derivative of formula I to form a second solid electrolyte layer [[ID=] can be manufactured by a manufacturing method including.
Advantages of the Invention
[0015] According to the present invention, an electrolytic capacitor with low ESR and low variation in LC can be provided.
Embodiments for Carrying Out the Invention
[0016] Hereinafter, the electrolytic capacitor of the present invention will be described more specifically.
[0017] When manufacturing the electrolytic capacitor of the present invention, first, a lead tab for an external lead electrode is connected to an anode foil having a dielectric oxide film and a cathode foil. By winding the anode foil and the cathode foil to which the lead tab is connected through a separator, a wound capacitor element is produced.
[0018] For the anode foil, a valve action metal foil (preferably an aluminum foil) whose surface has been roughened by etching and having a dielectric oxide film formed thereon by anodic oxidation can be used.
[0019] For the cathode foil, a valve action metal foil (preferably an aluminum foil) whose surface has been roughened by etching or a plain valve action metal foil not subjected to an etching treatment can be used. Further, a coating foil having a metal thin film or a carbon thin film formed on the surface of the roughened foil or the plain foil may be used.
[0020] For the separator, electrolytic paper mainly composed of cellulose such as kraft paper or manila paper, or mainly composed of synthetic fibers such as vinylon fiber, polyester fiber, acrylic fiber, or aramid fiber can be used.
[0021] In order to repair the cut surface of the capacitor element and the dielectric oxide film damaged during production, the capacitor element is subjected to a forming treatment. The forming treatment is performed by applying a voltage to the capacitor element in a forming solution. Examples of the forming solution used for the forming treatment include an aqueous solution containing phosphoric acid and / or phosphate, or adipic acid and / or adipate.
[0022] Optionally, the capacitor element after the forming treatment may be immersed in an aqueous solution in which polyvinyl alcohol and colloidal silica are dissolved, heated, and dried (for example, dried at 100 to 120 ° C for 30 to 60 minutes) to perform a pretreatment.
[0023] The capacitor element is impregnated with the first conductive polymer solution by immersing it in the first conductive polymer solution under normal pressure or reduced pressure, and then the capacitor element is heat-treated (e.g., 150-220°C) to form a first solid electrolyte layer immediately adjacent to the dielectric oxide film. The first solid electrolyte layer may be formed by repeating this process multiple times (e.g., 2-4 times).
[0024] The first conductive polymer solution contains a conductive polymer and a surfactant. Examples of conductive polymers included in the first conductive polymer solution include polyaniline, polypyrrole, polythiophene, polyethylenedioxythiophene, and their derivatives, with polyaniline or its derivatives being particularly preferred. Examples of polyaniline derivatives include polyaniline derivatives having a polyaniline skeleton and at least one of alkyl groups, phenyl groups, alkoxy groups, ester groups, and thioether groups as substituents. The concentration of the conductive polymer (e.g., polyaniline or its derivatives) in the first conductive polymer solution is not particularly limited, but is preferably 1 to 5 wt%, more preferably 2 to 3 wt%.
[0025] The surfactant contained in the first conductive polymer liquid is preferably a nonionic surfactant, and more preferably an acetylene-based surfactant. Acetylene-based surfactants (e.g., acetylene glycol-based, acetylenediol-based, acetylene alcohol-based surfactants) are nonionic surfactants having an acetylene structure in their molecules. Examples of acetylene-based surfactants include 2,4,7,9-tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octin-3,6-diol, 2,5,8,11-tetramethyl-6-dodecine-5,8-diol, 3,5-dimethyl-1-hexyn-3-ol, and their ethylene oxide adducts and ethoxylated derivatives. In particular, acetylene-based surfactants having an acetylene group in the center and carbon chains containing hydroxyl groups and / or ether bonds on either side are more preferred. Examples include acetylenediol-based surfactants, their ethylene oxide adducts, and ethoxylated derivatives. These surfactants are available on the market and are sold, for example, by Air Products Japan Co., Ltd. and Nisshin Chemical Industries, Ltd. under names such as Surfinol® and Dynol. A preferred example is Dynol 604 from Air Products Japan Co., Ltd. or Nisshin Chemical Industries, Ltd.
[0026] The concentration of the surfactant (more preferably a nonionic surfactant, and particularly preferably an acetylene-based surfactant) in the first conductive polymer liquid is preferably 0.05 to 1.0 wt%, more preferably 0.1 to 0.5 wt%, and particularly preferably 0.15 to 0.3 wt%.
[0027] The solvent of the first conductive polymer solution is basically water, but it may also contain organic solvents such as ethylene glycol. Furthermore, the first conductive polymer solution may contain additives such as antioxidants. It may also contain dopants selected from polystyrene sulfonic acid, p-toluenesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, and 1-naphthalenesulfonic acid.
[0028] In the first solid electrolyte layer formation step described above, the electrical conductivity of the first solid electrolyte layer can be adjusted by changing the ratio of organic solvents contained in the first conductive polymer solution.
[0029] By the method described above, a first solid electrolyte layer can be formed immediately adjacent to the dielectric oxide film. In the first solid electrolyte layer, the weight ratio of the conductive polymer (preferably aniline or a derivative thereof) to the surfactant (preferably an acetylene-based surfactant) is preferably 97:3 to 70:30, more preferably 95:5 to 75:25, and particularly preferably 93:7 to 80:20.
[0030] Furthermore, by adjusting the electrical conductivity as described above, the first solid electrolyte layer has an electrical conductivity of 0.01 S / cm or higher. A more preferable electrical conductivity is 0.05 to 30 S / cm, and a particularly preferable electrical conductivity is 0.1 to 10 S / cm.
[0031] Subsequently, the capacitor element with the first solid electrolyte layer formed on it is immersed in the second conductive polymer liquid under normal pressure or reduced pressure (preferably reduced pressure, for example, about 50 to 95 kPa) to impregnate it with the second conductive polymer liquid. Then, the capacitor element is heat-treated (for example, 70°C to 220°C) to form the second solid electrolyte layer. This process may be repeated multiple times (for example, 2 to 4 times).
[0032] The second conductive polymer liquid contains a polyethylenedioxythiophene derivative represented by the following formula I. TIFF2026119559000002.tif31169 (in the formula, x is an integer greater than or equal to 2 (preferably 8 or greater, more preferably 10 to 30, and particularly preferably 15 to 20), m is an integer between 1 and 10. n is either 0 or 1. M is a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. R is a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, a substituent alkyl group having 1 to 6 carbon atoms, or a fluorine atom.
[0033] The PEDOT derivative corresponding to formula I is a self-doped conductive polymer that is soluble in water. A preferred example is poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulfonic acid).
[0034] The second conductive polymer solution may contain only the PEDOT derivative of formula I as the conductive polymer, or it may contain other conductive polymers (preferably PEDOT). If the other conductive polymer is not a self-doped conductive polymer, it may contain a dopant selected from polystyrene sulfonic acid, p-toluenesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, and 1-naphthalenesulfonic acid, along with the other conductive polymer. The concentration of the conductive polymer in the second conductive polymer solution is not particularly limited, but is preferably 1 to 5 wt%, more preferably 2 to 3 wt%. Alternatively, a second solid electrolyte layer may be formed by impregnating with multiple types of second conductive polymer solutions. For example, the second solid electrolyte layer may include a layer consisting only of the PEDOT derivative of formula I, and a layer consisting of PEDOT / PSS and the PEDOT derivative of formula I.
[0035] The solvent for the second conductive polymer solution is basically water, but it may also contain organic solvents such as ethylene glycol. Furthermore, the second conductive polymer solution may contain additives such as antioxidants.
[0036] The second solid electrolyte layer containing the PEDOT derivative of formula I, formed as described above, typically has a higher electrical conductivity than the first solid electrolyte layer. For example, an electrolytic capacitor in which the electrical conductivity of the first solid electrolyte layer is 10 S / cm or less and the electrical conductivity of the second solid electrolyte layer is higher than 10 S / cm can be found. The electrical conductivity of the second solid electrolyte layer is preferably 100 S / cm or more, more preferably 200 S / cm or more, and particularly preferably 300 to 500 S / cm.
[0037] The electrical conductivity of the second solid electrolyte layer can be adjusted by changing the mixing ratio of the PEDOT derivative of formula I and other conductive polymers (preferably PEDOT, more preferably PEDOT / PSS) contained in the second conductive polymer solution.
[0038] Afterward, optionally, the capacitor element with the second solid electrolyte layer formed on it may be immersed in a polyalkylene glycol solution or the like under reduced pressure (e.g., 50-95 kPa) and heated and dried (e.g., at 110-150°C for 15-60 minutes).
[0039] By following the above process, a capacitor element is fabricated in which a first solid electrolyte layer is formed immediately adjacent to the dielectric oxide film, and a second solid electrolyte layer is formed on top of the first solid electrolyte layer. Then, the lead terminals extending from this capacitor element are inserted through the lead insertion holes of the sealing material and the capacitor element and sealing material are housed in an outer case (a case made of metal such as aluminum). The opening of the outer case is curled, and the capacitor is subjected to an aging process by applying the rated voltage at a temperature of approximately 150°C, thereby fabricating an electrolytic capacitor. [Examples]
[0040] The present invention will be described more specifically below using examples, but the present invention is not limited to these examples.
[0041] [Fabrication of capacitor elements] Aluminum lead rods for external lead electrodes were connected to each of the anode and cathode foils, which had been cut to a predetermined width. For the anode foil, an aluminum foil with a dielectric oxide film formed on its surface by pre-etching and chemical conversion treatment was used. For the cathode foil, an aluminum foil with carbon vapor deposition was used. The anode and cathode foils were wound together with a separator (electrolytic paper mainly composed of cellulose) in between to form a capacitor element. Subsequently, in order to repair the dielectric oxide film damaged during the cutting of the anode foil and the attachment of the external lead electrodes, the capacitor element was immersed in a 2 wt% ammonium adipate aqueous solution, and a conversion treatment was performed by applying a voltage approximating the conversion voltage value of the dielectric oxide film. Next, the capacitor elements after chemical conversion treatment were pre-treated by immersing them in an aqueous solution containing dissolved polyvinyl alcohol (PVA) and colloidal silica under normal pressure and drying them at 105°C for 40 minutes.
[0042] [Formation of the first electrolyte layer] A capacitor element was immersed under normal pressure in a polyaniline solution, or in a polyaniline solution (first conductive polymer solution; polyaniline concentration 1.0 wt%) to which 0.2 wt% of the acetylene-based surfactant 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol,ethoxylated (Dynol 604, Air Products Japan Co., Ltd.) was added (first conductive polymer solution; polyaniline concentration 1.0 wt%), and dried at 180°C to form a first solid electrolyte layer. The electrical conductivity of the first solid electrolyte layer was adjusted by adding an organic solvent to the first conductive polymer solution.
[0043] [Formation of the second solid electrolyte layer] Next, under reduced pressure of 90 kPa, the capacitor elements were immersed for 30 minutes in a 2 wt% conductive polymer solution (second conductive polymer solution) containing PEDOT / PSS and / or poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulfonic acid), a PEDOT derivative of formula I. After immersion, the elements were dried in a constant temperature bath at 85°C / 30 minutes + 160°C / 30 minutes. The same impregnation / drying procedure was repeated twice to form a second solid electrolyte layer within the capacitor elements.
[0044] Subsequently, the capacitor elements were fabricated by immersing them in a polyalkylene glycol solution under reduced pressure of 90 kPa and drying them at 135°C for 30 minutes.
[0045] [Making a Capacitor] The capacitor element was housed in an aluminum outer case, and the opening of the outer case was curled to create a closed system. The electrolytic capacitor housed in the outer case was subjected to an aging process in a constant temperature bath set to 150°C by applying the rated voltage, thereby completing the electrolytic capacitor (size: φ8 × 10L / 80V-27μF). The type of solid electrolyte used in each electrolytic capacitor is shown in Table 1.
[0046] The electric conductivities of the first and second electrolyte layers were measured by applying the first and second conductive polymer solutions onto a glass substrate and forming a film made of the conductive polymer, respectively. In addition, ESR and LC were measured, and the variation in LC was calculated from the LC values of 30 capacitors.
[0047] The results are shown in Table 1. In Comparative Example 6 and Example 6, the weight ratio of the PEDOT / PSS of the second solid electrolyte to the PEDOT derivative of Formula I was 3:1. TIFF2026119559000003.tif194170
[0048] As is clear from Comparative Examples 1 to 5, when the first solid electrolyte layer does not contain a surfactant, as the electric conductivity of the first solid electrolyte layer increases, although the ESR value of the capacitor decreases, the variation in LC increases. Further, from the comparison of Comparative Examples 5 to 7, when the first solid electrolyte layer does not contain a surfactant, it was observed that the variation in LC tended to be smaller when the second solid electrolyte layer contained PEDOT / PSS, but it did not decrease to a sufficient extent. Also, from the comparison of Comparative Examples 7 and 8, it was found that when the second solid electrolyte is only PEDOT / PSS, even if the first solid electrolyte layer contains a surfactant, there is almost no difference in the variation in LC.
[0049] Even when the first solid electrolyte layer contains a surfactant and the second solid electrolyte layer contains the PEDOT derivative of Formula I, when the electric conductivity of the first solid electrolyte layer is 0.001 (10 -3 ), the variations in ESR and LC were about the same as those in Comparative Example 1. However, as is clear from Examples 1 to 5, when the electric conductivity of the first solid electrolyte layer is 0.01 (10 -2 ) or more, as the electric conductivity of the first solid electrolyte layer increases, not only does the ESR value decrease, but the variation in LC also decreases. The effect of improving the LC variation was remarkable compared with Comparative Examples 2 to 5. Also, when the second solid electrolyte layer contains PEDOT / PSS in addition to the PEDOT derivative of Formula I (Example 6), an electrolytic capacitor with both low ESR and low LC variation could be obtained.
[0050] In summary, when a self-doped conductive polymer of formula I is used as the second solid electrolyte, as shown in Comparative Examples 2 to 5, the ESR can be reduced by increasing the electrical conductivity of the first solid electrolyte layer, but the LC characteristics deteriorate significantly, so it was necessary to keep the electrical conductivity of the first solid electrolyte layer below 0.01 S / cm. In contrast, when a surfactant is included in the first solid electrolyte layer, the LC variation does not worsen even when the electrical conductivity of the first solid electrolyte layer is increased above 0.01 S / cm, and rather, a tendency for the LC variation to decrease as the electrical conductivity of the first solid electrolyte layer increases was observed. Therefore, according to the present invention, it is possible to provide an electrolytic capacitor with excellent ESR characteristics and LC characteristics.
Claims
1. An electrolytic capacitor having a capacitor element in which an anode foil having a dielectric oxide film and a cathode foil are wound with a separator in between, The capacitor element has a first solid electrolyte layer and a second solid electrolyte layer on a dielectric oxide film. The first solid electrolyte layer is a layer immediately adjacent to the dielectric oxide film, and contains a conductive polymer and a surfactant, and has an electrical conductivity of 0.01 S / cm or higher. The second solid electrolyte layer contains a polyethylenedioxythiophene (PEDOT) derivative represented by the following formula I, (In the formula, x is an integer greater than or equal to 2, m is an integer between 1 and 10. n is either 0 or 1, M is a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. R is a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, a substituent alkyl group having 1 to 6 carbon atoms, or a fluorine atom. Electrolytic capacitors characterized by the following features.
2. The electrolytic capacitor according to claim 1, wherein the first solid electrolyte layer comprises polyaniline or a derivative thereof and an acetylene-based surfactant.
3. The electrolytic capacitor according to claim 2, wherein the acetylene-based surfactant is selected from 2,5,8,11-tetramethyl-6-dodecine-5,8-diol or an ethoxylated derivative thereof.
4. A method for manufacturing an electrolytic capacitor according to any one of claims 1 to 3, A step of preparing a capacitor element in which an anode foil having a dielectric oxide film and a cathode foil are wound around a separator, A step of impregnating the capacitor element with a first conductive polymer solution containing a conductive polymer and a surfactant to form a first solid electrolyte layer having an electrical conductivity of 0.01 S / cm or more. Next, the capacitor element is impregnated with a second conductive polymer solution containing a PEDOT derivative of formula I to form a second solid electrolyte layer. A method for manufacturing an electrolytic capacitor, characterized by including the following: