JP6578505B2 - Electrolytic capacitor - Google Patents

Description

  The present invention relates to a power storage device used for various electronic devices, industrial devices, automotive devices and the like.

  With the increase in the frequency of electronic equipment, electrolytic capacitors that are one of power storage devices are also required to have excellent equivalent series resistance (hereinafter referred to as ESR) characteristics in a high frequency region.

  Recently, in order to reduce ESR in such a high frequency region, a solid electrolytic capacitor using a solid electrolyte such as a conductive polymer having a higher electric conductivity than a conventional electrolytic solution has been studied and commercialized as an electrolyte. Such a solid electrolytic capacitor has a configuration in which a conductive polymer is filled in an element wound with a separator interposed between an anode foil and a cathode foil. (For example, patent document 1).

  In addition, since the solid electrolytic capacitor as described above uses only a solid electrolyte having a poor dielectric oxide film repairability as an electrolyte, the leakage current is increased as compared with an electrolytic capacitor using a conventional electrolytic solution. Electrolytic capacitors that use both solid electrolytes and electrolytes made of conductive polymers as electrolytes to improve such problems are prone to short failures due to the occurrence of dielectric oxide film defects. Proposed. (For example, patent document 2).

JP-A-63-158829 Japanese Patent Laid-Open No. 7-283086

  As described above, an electrolytic capacitor having excellent ESR characteristics can be realized by using a solid electrolyte as an electrolyte or by using both a solid electrolyte and an electrolytic solution.

  On the other hand, with the recent demands for improving safety and reliability of electronic devices, improvements in safety and reliability have also been demanded in the above electrolytic capacitors.

  Therefore, an object of the present invention is to provide an electrolytic capacitor with improved reliability in an electrolytic capacitor having excellent ESR characteristics.

  In order to achieve the above object, an electrolytic capacitor of the present invention includes a capacitor element in which an anode foil having a dielectric layer on its surface is wound, a lead tab terminal connected to the anode foil and led out from one end face of the capacitor element. A solid electrolyte containing a conductive polymer impregnated in the capacitor element, and the amount of the conductive polymer deposited on the other end face where the lead tab terminal is not led on the opposite side of the one end face of the capacitor element. More than the amount of the conductive polymer deposited on one end face of the capacitor element.

According to the electrolytic capacitor of the present invention, it is possible to prevent a short circuit between the inner bottom surface of the case of the electrolytic capacitor and the electrode foil end surface of the capacitor element, and to reduce the leakage current between the lead tab terminals. As a result, an electrolytic capacitor with improved reliability can be obtained.

Schematic sectional view of an electrolytic capacitor in an embodiment of the present invention 1 is a schematic perspective view of a capacitor element 12 in the electrolytic capacitor shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the aspect ratio of some dimensions is changed for easy understanding.

(Embodiment)
FIG. 1 is a schematic cross-sectional view of an electrolytic capacitor according to an embodiment of the present invention. FIG. 2 is a schematic perspective view of the capacitor element 12 in the electrolytic capacitor 1 shown in FIG.

  As shown in FIG. 1, the electrolytic capacitor 1 of the present invention has a structure in which a capacitor element 12 is enclosed in an exterior body 15.

  As shown in FIG. 2, the capacitor element 12 includes an anode foil 21 having a dielectric layer on the surface, a cathode foil 22, a separator 23, a lead tab terminal 17, and a conductive polymer 18 constituting a solid electrolyte 24.

  Lead tab terminals 17 are connected to the anode foil 21 and the cathode foil 22, respectively. The anode foil 21 and the cathode foil 22 are wound by inserting a separator 23 between the anode foil 21 and the cathode foil 22 to form the winding element 11.

  The lead tab terminal 17 is led out of the capacitor element 12 from one end face 19 </ b> A of the capacitor element 12.

  The capacitor element 12 is enclosed in an exterior body 15 having a case 13 and a sealing body 14, and the lead tab terminal 17 is led out through a through hole 16 provided in the sealing body 14.

  The conductive polymer 18 is deposited on the anode foil 21, the cathode foil 22, and the separator 23 and functions as a solid electrolyte 24.

  And the conductive polymer in the other end surface 19B where the lead tab terminal 17 is not led out, opposite to the inner bottom surface of the case 13, opposite to the one end surface 19A from which the lead tab terminal 17 is led out of the capacitor element 12. The deposition amount of 18 is larger than the deposition amount of the conductive polymer 18 on one end surface 19A of the capacitor element 12.

  One end surface when the amount of the conductive polymer deposited on the other end surface 19B of the capacitor element 12 opposite to the one end surface from which the lead tab terminal 17 is derived is not derived, is 100. The amount of the conductive polymer 18 deposited in 19A is preferably 95 or less by weight.

  The anode foil 21 is roughened by etching a metal foil made of a valve metal such as aluminum, and a dielectric layer is formed on the surface by chemical conversion or the like. On the other hand, the cathode foil 22 is formed of a metal such as aluminum.

  The cathode foil 22 may be provided with a chemical film on the surface of a metal such as aluminum, or may be provided with a film of a different metal or nonmetal. Examples of dissimilar metals and nonmetals include metals such as titanium and nonmetals such as carbon.

  The material of the lead tab terminal 17 is not particularly limited as long as it is a conductive material, but at least the joining portion with the anode foil 21 and the cathode foil 22 is made of the same material as the anode foil 21 and the cathode foil 22. Is preferred.

  The surface of the lead tab terminal 17 may be subjected to chemical conversion treatment. Moreover, the part which contacts the sealing body 14 of the lead tab terminal 17 may be covered with the resin material.

  The separator 23 contains cellulose fibers. Cellulose fiber is a general term for fibers mainly composed of cellulose. In addition to natural fibers obtained from natural materials such as Manila hemp, esparto, hemp, kraft pulp and bamboo, these natural materials are once dissolved. Recycled fibers such as rayon obtained by spinning and spinning, and semisynthetic fibers such as acetate obtained by chemical treatment of natural materials. The separator 23 may include fibers other than cellulose fibers, such as polyethylene terephthalate, vinylon, polyamide fibers (aliphatic polyamide fibers such as nylon and aromatic polyamide fibers such as aramid). The cellulose fibers preferably account for 50% by mass or more of the fibers contained in the separator. The cellulose fibers are preferably not fibrillated (separated). This is because the movement of the conductive polymer particles becomes easier and the conductive polymer particles easily reach the dielectric layer.

  The air permeability of the separator 23 is preferably 1 to 150 s / 100 ml, and more preferably 1 to 60 s / 100 ml. When the air permeability of the separator is within this range, the movement of the conductive polymer particles becomes easier, and the conductive polymer particles easily reach the dielectric layer. The air permeability is measured based on JIS P8117 using a Gurley type air permeability tester. The thickness of the separator 23 is preferably 10 to 100 μm. The effect which suppresses the short circuit of an electrolytic capacitor becomes higher that thickness is this range.

  Examples of the conductive polymer 18 contained in the solid electrolyte 24 include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polythiophene vinylene, and the like. These may be used alone or in combination of two or more, or may be a copolymer of two or more monomers. In the present specification, polypyrrole, polythiophene, polyfuran, polyaniline and the like mean polymers having a basic skeleton of polypyrrole, polythiophene, polyfuran, polyaniline and the like, respectively. Accordingly, polypyrrole, polythiophene, polyfuran, polyaniline and the like can also include respective derivatives. For example, polythiophene includes poly (3,4-ethylenedioxythiophene) and the like.

  The conductive polymer 18 may contain a dopant. Examples of the dopant include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacryl sulfonic acid, polymethacryl sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, and polyacrylic. And anions such as acids. Of these, polyanions derived from polystyrene sulfonic acid are preferred. These may be used alone or in combination of two or more. These may be a single monomer polymer or a copolymer of two or more monomers.

  The conductive polymer 18 also functions as the cathode of the electrolytic capacitor 1.

  Further, an electrolytic solution may be used in combination with the solid electrolyte 24 containing the conductive polymer 18. By using the electrolytic solution in combination, the withstand voltage of the electrolytic capacitor can be improved. The electrolytic solution enters the gaps formed in the gaps in the separator 23 and the etching pits of the anode foil 21 and has a function of repairing the defective portion of the dielectric layer.

  The electrolytic solution is prepared by dissolving a solute in an organic solvent. As the organic solvent, alcohols, aprotic amide solvents, lactones, sulfoxides, and the like can be used. Examples of alcohols include methanol, ethanol, propanol, butanol, cyclobutanol, cyclohexanol, ethylene glycol, propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, and polycondensates of glycols. Examples of the amide solvent include N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide and the like. Examples of lactones include γ-butyrolactone, β-butyrolactone, α-valerolactone, and γ-valerolactone. Examples of the sulfoxides include sulfolane, 3-methyl sulfolane, dimethyl sulfoxide and the like.

  The base component of the electrolyte component that is a solute is a compound having an alkyl-substituted amidine group, and examples thereof include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds). Further, as the base component of the electrolyte component, quaternary ammonium of a compound having an alkyl-substituted amidine group can be used, and as quaternary ammonium of a compound having an alkyl-substituted amidine group, an alkyl group having 1 to 11 carbon atoms or Examples thereof include an imidazole compound quaternized with an arylalkyl group, a benzimidazole compound, and an alicyclic amidine compound (pyrimidine compound, imidazoline compound). As base components, ammonium, primary amine (methylamine, ethylamine, propylamine, butylamine ethylenediamine, monoethanolamine, etc.), secondary amine (dimethylamine, diethylamine, dipropylamine, ethylmethylamine, diphenylamine, diethanolamine, etc.) Tertiary amines (trimethylamine, triethylamine, tributylamine, 1,8-diazabicyclo (5,4,0) -undecene-7, triethanolamine, etc.) may be used.

  As the acid component of the electrolyte component, an aliphatic carboxylic acid such as a saturated carboxylic acid, an unsaturated carboxylic acid, or an aromatic carboxylic acid can be used. Examples of aliphatic saturated carboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, and 5,6-decanedicarboxylic acid. , Formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid and the like. Aliphatic unsaturated carboxylic acids include maleic acid, fumaric acid, itonic acid, acrylic acid, methacrylic acid and oleic acid. Examples of the aromatic carboxylic acid include phthalic acid, salicylic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, benzoic acid, resorcinic acid, cinnamic acid, and naphthoic acid. Besides these carboxylic acids, nitro derivatives and sulfonic acid derivatives of carboxylic acids, phosphoric acid derivatives and boric acid derivatives that are inorganic acids, and the like can be used as the acid component of the electrolyte.

  The outer package 15 seals the capacitor element 12 and the electrolytic solution (when an electrolytic solution is used in combination) as the end of the lead tab terminal 17 drawn from the capacitor element 12 is led out.

The exterior body 15 includes a case 13 and a sealing body 14. The case 13 houses the capacitor element 12. The sealing body 14 is provided with a through hole 16 through which the lead tab terminal 17 is inserted. The sealing body 14 is disposed at the opening of the case 13 and is compressed by squeezing the outer peripheral surface of the case 13 with the drawing portion 13A, thereby sealing the opening of the case 13.

  The sealing body 14 can be made of a rubber material such as ethylene propylene rubber or butyl rubber which is a copolymer of isobutyl and isoprene, or a resin material such as an epoxy resin.

  Case 13 is made of metal. From the viewpoint of weight reduction, the case 13 is preferably formed of aluminum.

  Then, the manufacturing method of the electrolytic capacitor in embodiment is demonstrated.

  First, the winding element 11 is formed.

  An anode foil 21 and a cathode foil 22 that are electrode bodies of the electrolytic capacitor 1 are prepared.

  The anode foil 21 is roughened by performing etching or the like on the surface of the metal foil, and further, a dielectric layer is formed on the surface of the roughened metal foil by chemical conversion or the like.

  As the etching process, for example, a DC electrolysis method or an AC electrolysis method may be applied. As the chemical conversion treatment, for example, a voltage may be applied in a state where the metal foil is immersed in a chemical conversion solution such as an ammonium adipate solution.

As the cathode foil 22, a metal foil may be used as it is, or a surface thereof may be roughened.
As a method for roughening the surface, an etching process can be applied in the same manner as the anode foil 21.

  Then, the lead tab terminal 17 is connected to the anode foil 21 and the cathode foil 22 having a dielectric layer formed on the surface.

  The anode foil 21 and the cathode foil 22 to which the lead tab terminal 17 is connected are overlapped via a separator 23 and wound to form a winding element 11.

  At this time, the lead tab terminal 17 connected to the anode foil 21 and the lead tab terminal 17 connected to the cathode foil 22 are led out only from one end face 19A of the winding element 11, as shown in FIG.

  When preparing the anode foil 21 by cutting a wide or long metal foil, in order to provide a dielectric layer on the cut surface of the anode foil 21, before the conductive polymer is deposited, After the winding element 11 is formed, chemical conversion treatment may be further performed.

  Next, the conductive polymer 18 is attached to the winding element 11 to form the capacitor element 12.

  As a method for depositing the conductive polymer 18 on the winding element 11, for example, the following method can be applied.

First, a dispersion liquid in which fine particles of conductive polymer are dispersed in a dispersion medium is placed on the other end surface 19B of the winding element 11 where the lead tab terminal 17 of the winding element 11 is not led upward. After supplying a certain amount of the dispersion liquid to the end face 19B and allowing it to stand for a while, all or part of the dispersion medium in the dispersion liquid supplied to the winding element 11 is removed by a method such as heating or decompression. By this operation, the conductive polymer 18 is deposited on the winding element 11 and the solid electrolyte 24 is formed.

  The increase or decrease in the amount of the conductive polymer 18 deposited on one end surface 19A and the other end surface 19B of the winding element 11 supplies a dispersion to the other end surface 19B of the winding element 11. After that, it is controlled by increasing or decreasing the standing time until the dispersion medium in the dispersion is removed. That is, the shorter the time from supplying the dispersion liquid to the other end face 19B of the winding element 11 to removing the dispersion medium in the dispersion liquid is shorter, the other end face of the winding element 11 after the dispersion medium is removed. The longer the time until 19B is coated with a large amount of the conductive polymer 18 and the dispersion medium is removed, the more the dispersion penetrates into the winding element 11, so that the winding element 11 While the amount of the conductive polymer 18 deposited on the other end surface 19B decreases, the amount of the conductive polymer 18 deposited on the inside of the winding element 11 and one end surface 19A of the winding element 11 increases.

    Note that, when the electrolytic solution is impregnated into the capacitor element 12 to which the conductive polymer 18 is adhered, the method is not particularly limited. For example, the method of immersing the capacitor element 12 in the electrolytic solution contained in the container Alternatively, a method of dropping the electrolytic solution onto the capacitor element 12 can be used. The impregnation may be performed under reduced pressure, for example, in an atmosphere of 10 kPa to 100 kPa, preferably 40 kPa to 100 kPa.

Next, the capacitor element 12 to which the conductive polymer 18 is adhered is housed in the case 13 and sealed.

  Specifically, first, the capacitor element 12 to which the conductive polymer 18 is attached is arranged so that the one end surface 19A side from which the lead tab terminal 17 of the capacitor element 12 is led is positioned on the opening side of the case 13. Store in case 13.

  Then, the sealing body 14 is disposed at the opening of the case 13 so that the lead tab terminal 17 penetrates the through hole 16 provided in the sealing body 14, and lateral drawing and curling are performed on the opening end of the case 13. And the case 13 is sealed.

  When an electrolyte is used in combination with the solid electrolyte 24 containing the conductive polymer 18 as an electrolyte, the capacitor element 12 is stored in the case 13 after the capacitor element 12 is impregnated with the electrolyte as described above. However, the electrolytic solution may be injected into the case 13 after the capacitor element 12 is stored in the case 13, or the capacitor element 12 may be stored in the case 13 after the electrolytic solution is injected into the case 13.

  The electrolytic capacitor 1 after the capacitor element 12 is sealed in the case 13 may be subjected to an aging process while applying a rated voltage.

  As described above, the electrolytic capacitor 1 of the present invention has the conductivity at the other end surface 19B of the capacitor element 12 opposite to the one end surface 19A from which the lead tab terminal 17 is derived and from which the lead tab terminal 17 is not derived. By making the deposition amount of the polymer 18 larger than the deposition amount of the conductive polymer 18 on one end surface 19A of the capacitor element 12, the end surface of the anode foil 21 on the other end surface 19B of the capacitor element 12; The amount of the conductive polymer 18 existing between the inner bottom surface of the case 13 increases, and the lead tab terminal 17 on the anode foil 21 side and the lead tab terminal 17 on the cathode foil 22 side of one end surface 19A of the capacitor element 12 are increased. The amount of the conductive polymer 18 existing between the two is reduced.

As described above, the conductive polymer 18 having a conductivity lower than that of the metal is present between the end face of the anode foil 21 and the inner bottom face of the metal case 13 even though it is conductive. Foil 2
1 is difficult to directly contact the case 13 and the anode foil 21 and the case 13 can be prevented from being short-circuited. In addition, since the conductive polymer 18 existing between the lead tab terminal 17 on the anode foil 21 side and the lead tab terminal 17 on the cathode foil 22 side is reduced, the lead tab terminal 17 on the anode foil 21 side and the cathode foil 22 side are side by side. Leakage current between the lead tab terminals 17 can be reduced.

  That is, when the amount of the conductive polymer deposited on one end surface and the other end surface of the capacitor element is the same as in a conventional electrolytic capacitor, the short circuit between the anode foil and the case is prevented, and the anode side Although it was difficult to achieve both a reduction in leakage current between the lead tab terminal and the cathode side lead tab terminal, the amount of conductive polymer deposited on one end surface of the capacitor element, The lead tab terminal of the capacitor element is derived as in the configuration of the present invention, when the amount of deposition combined with the amount of deposition of the conductive polymer deposited on the other end surface is the same as the conventional amount. The amount of the conductive polymer deposited on the other end surface where the lead tab terminal is not led out is larger than the amount of the conductive polymer deposited on the one end surface of the capacitor element. By making it possible It made.

Next, examples will be described. In addition, this invention is not limited to the content described in these Examples at all.
Example 1
<Formation of winding element>
First, the winding element before depositing the conductive polymer was formed.

  The anode foil used as the electrode body of the electrolytic capacitor is an aluminum foil having a thickness of 105 μm. After the surface of the aluminum foil is roughened by etching treatment, the roughened surface becomes a dielectric layer by anodizing treatment. An aluminum oxide film was formed. As the cathode foil, an aluminum foil having a thickness of 50 μm was used, and the surface of the aluminum foil was roughened by etching.

  A separator made of natural fiber having a thickness of 50 μm was used.

  The lead tab terminals made of aluminum were connected to the anode foil and the cathode foil by needle caulking, respectively, and the anode foil and the cathode foil were overlapped and wound via a separator to form a winding element.

<Formation of capacitor element>
Next, a conductive polymer serving as a solid electrolyte layer was deposited on the wound element to form a capacitor element.

  As the conductive polymer to be deposited on the winding element, poly 3,4-ethylenedioxythiophene (hereinafter referred to as PEDOT) containing polystyrene sulfonic acid as a dopant was used.

  First, a dispersion in which fine particles of PEDOT are dispersed in a dispersion medium containing water as a main component, with the other end face from which the lead tab terminal is not led up facing the other end of the winding element, After supplying a certain amount of the dispersion liquid to the end face, and leaving a part of the dispersion liquid supplied to the end face of the winding element penetrates to one end face where the lead tab terminal is led out from the inside of the winding element, The winding element was heated to remove the dispersion medium in the dispersion supplied to the winding element, thereby forming a capacitor element in which PEDOT was attached to the winding element.

In Example 1, the amount of PEDOT deposited on the other end face where the lead tab terminal of the winding element is not derived, and the PED adhered on one end face where the lead tab terminal is derived.
The ratio of the amount of OT was 10 to 0.5 by weight.

<Production of electrolytic capacitor>
Next, the capacitor element to which PEDOT was attached was housed in a case in which an electrolytic solution was previously injected to produce an electrolytic capacitor.

  The case used as the exterior body was made of aluminum.

  The sealing body for sealing the opening of the case was made of butyl rubber.

  First, the capacitor element to which PEDOT is attached is accommodated in the case so that the anode lead tab terminal and the cathode lead tab terminal are located on the opening side of the case.

  Then, the sealing body is disposed in the opening of the case so that the lead tab terminal penetrates the through hole provided in the sealing body, and the case 13 is sealed by performing lateral drawing and curling on the opening end of the case. Then, an electrolytic capacitor was produced.

In Example 1, an electrolytic capacitor having a rated voltage of 35 V and a capacity of 47 μF was produced.
(Example 2)
In Example 2, the time from supplying the dispersion liquid to the other end face of the winding element to removing the dispersion medium in the dispersion liquid by heating the winding element is longer than that in Example 1. A capacitor element and an electrolytic capacitor were manufactured under the same conditions as in Example 1 in terms of materials and manufacturing methods.

In Example 2, the ratio of the amount of PEDOT deposited on the other end surface from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end surface is 10 by weight. It was set to 5.
(Example 3)
In Example 3, the time from supplying the dispersion liquid to the other end face of the winding element to removing the dispersion medium in the dispersion liquid by heating the winding element was longer than in Example 2. A capacitor element and an electrolytic capacitor were manufactured under the same conditions as in Example 2 in terms of materials and manufacturing methods.

In Example 3, the ratio of the amount of PEDOT deposited on the other end face from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end face is 10 by weight. It was set to 8.5.
Example 4
In Example 4, the time from supplying the dispersion liquid to the other end face of the winding element until heating the winding element to remove the dispersion medium in the dispersion liquid was longer than in Example 3. A capacitor element and an electrolytic capacitor were manufactured under the same conditions as in Example 3 in terms of materials and manufacturing methods.

In Example 4, the ratio of the amount of PEDOT deposited on the other end face from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end face is 10 by weight. It was set to 9.5.
(Example 5)
In Example 5, the time from supplying the dispersion to the other end face of the winding element and heating the winding element to remove the dispersion medium in the dispersion is shorter than in Example 1, The material, the manufacturing method, and the like are the same as those in Example 1, except that PEDOT is attached to the other end surface from which the lead tab terminal of the winding element is not derived and PEDOT is not attached to one end surface. Thus, a capacitor element and an electrolytic capacitor were produced.

Next, a comparative example will be described.
(Comparative Example 1)
Comparative Example 1 corresponds to the configuration of an electrolytic capacitor using a conventional solid electrolyte.

  In Comparative Example 1, the time from supplying the dispersion liquid to the other end face of the winding element to heating the winding element to remove the dispersion medium in the dispersion liquid was longer than that of Example 4. A capacitor element and an electrolytic capacitor were manufactured under the same conditions as in Example 4 in terms of materials and manufacturing methods.

In this comparative example 1, the ratio of the amount of PEDOT deposited on the other end surface from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end surface is 10 by weight. There were 10 pairs.
(Comparative Example 2)
In Comparative Example 2, the material and the manufacturing method are the same as in Example 4 except that the dispersion liquid is supplied to one end surface with one end surface of the winding element facing upward. Thus, a capacitor element and an electrolytic capacitor were produced.

In this comparative example 2, the ratio of the amount of PEDOT deposited on the other end face from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end face is 9 by weight. .5 to 10.
(Comparative Example 3)
In Comparative Example 3, the material and the manufacturing method are the same as those in Example 3 except that the dispersion liquid is supplied to one end surface with one end surface of the winding element facing upward. Thus, a capacitor element and an electrolytic capacitor were produced.

In Comparative Example 3, the ratio of the amount of PEDOT deposited on the other end face from which the lead tab terminal of the winding element was not derived and the amount of PEDOT deposited on one end face was 8 by weight. .5 to 10.
(Comparative Example 4)
In Comparative Example 4, the material and the manufacturing method are the same as in Example 2 except that the dispersion liquid is supplied to one end surface with one end surface of the winding element facing upward. Thus, a capacitor element and an electrolytic capacitor were produced.

In this comparative example 4, the ratio of the amount of PEDOT deposited on the other end face from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end face is 5 by weight. There were 10 pairs.
(Comparative Example 5)
In Comparative Example 5, the material and the manufacturing method are the same as those in Example 1 except that the dispersion liquid is supplied to one end surface with one end surface of the winding element facing upward. Thus, a capacitor element and an electrolytic capacitor were produced.

  In this comparative example 5, the ratio of the amount of PEDOT deposited on the other end surface from which the lead tab terminal of the winding element is not derived and the amount of PEDOT deposited on one end surface is 0 by weight. .5 to 10.

  In the above examples and comparative examples, the amount of PEDOT deposited on one end face and the other end face of the winding element was confirmed by atomic absorption analysis.

  Further, the end face of the winding element to which PEDOT is applied has a PEDOT color tone, and the color tone has a light and shade so as to be proportional to the amount of PEDOT applied to the end face. That is, in Examples 1-5, the color of the other end surface of a winding element has a darker color (dark blue of implementation PEDOT) than the color of one end surface.

  Moreover, the tendency is recognized not only in the end face of the winding element but also in the inside of the winding element, and the color near the other end face of the winding element of the separator to which PEDOT is deposited is in the vicinity of one end face. It has a color darker than the color (dark blue of PEDOT).

In Examples 1 to 5 (and Comparative Examples 1 to 5), the PEDOT deposition amount was 15 to 300 μg / mm ³ so that the amount of the PEDOT deposited per unit volume in the gap of one winding element was 15 to 300 μg / mm ³ . A winding element was impregnated with a dispersion in which fine particles were dispersed in a dispersion medium to produce a capacitor element.
(Evaluation of electrolytic capacitors)
The electrolytic capacitors produced in Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated.

  In the evaluation, the electrolytic capacitor was subjected to a vibration test, and the leakage current value between the lead tab terminals before and after the vibration test was measured.

  The vibration test was performed under the conditions of a frequency of 10 Hz to 55 Hz (reciprocating for 1 minute), a total amplitude of 1.5 mm, a vibration direction and a time of 2 hours each in three directions perpendicular to each other for a total time of 6 hours.

  The LC characteristics were measured after applying the rated voltage for 3 minutes to the product in a room temperature atmosphere.

  The results are shown in Table 1.

  In Table 1, an evaluation result equivalent to Comparative Example 1 corresponding to a conventional electrolytic capacitor is indicated by Δ, a better one than Comparative Example 1 is indicated by ◯, and an evaluation result worse than Comparative Example 1 is indicated by ×.

  As shown in Table 1, the LC value of the electrolytic capacitor before being subjected to the vibration test is that the electrolytic capacitors of Examples 1 to 5 are more than the electrolytic capacitors of Comparative Example 1 and Comparative Examples 2 to 5 corresponding to conventional electrolytic capacitors. Also has good results. And even after going through a vibration test, the LC values of the electrolytic capacitors of Examples 1 to 5 do not deteriorate, and the results are better than those of Comparative Example 1 and the electrolytic capacitors of Comparative Examples 2 to 5 in which the LC values are deteriorated. It has become.

As described above, like the electrolytic capacitors of Examples 1 to 5, the conductive polymer on the other end face where the lead tab terminal is not led out, on the opposite side of the one end face where the lead tab terminal of the capacitor element is led out. The electrolytic capacitor provided with the capacitor element in which the deposition amount of the conductive polymer is larger than the deposition amount of the conductive polymer on one end face can achieve both the initial LC characteristics and the LC characteristics after the vibration test. As a result, an electrolytic capacitor with improved reliability can be obtained.

  The present invention can be applied to an electrolytic capacitor using a conductive polymer as a solid electrolyte.

DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 11 Winding element 12 Capacitor element 13 Case 13A Drawing part 14 Sealing body 15 Exterior body 16 Through hole 17 Lead tab terminal 18 Conductive polymer 19A One end surface 19B The other end surface 21 Anode foil 22 Cathode foil 23 Separator 24 Solid electrolyte

Claims (5)

A winding element in which an anode foil having a dielectric layer on its surface is wound, a lead tab terminal connected to the anode foil and led out from one end face of the winding element, and a dispersion containing a conductive polymer A capacitor element having a solid electrolyte formed by impregnating a winding element;
When the amount of conductive polymer deposited on the other end face of the capacitor element is 10, the amount of conductive polymer deposited on the one end face of the capacitor element is 5 or less. Electrolytic capacitor. 2. The electrolytic capacitor according to claim 1, wherein a conductive polymer is not deposited on the one end face. The electrolytic capacitor according to claim 1, wherein the capacitor element is impregnated with an electrolytic solution. 4. The electrolytic capacitor according to claim 1, wherein the capacitor element includes a cathode foil and a separator wound between the anode foil and the cathode foil. 5. . 5. The electrolytic capacitor according to claim 1, further comprising: an outer case that houses the capacitor element; and a sealing body that seals an opening of the outer case.

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