JP4115359B2 - Electrolytic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrolytic capacitor using a conductive polymer layer as a solid electrolyte and a method for manufacturing the same.

Along with the digitization of electronic equipment, the capacitors used therefor are also required to be small in size, large capacity, and low in equivalent series resistance (hereinafter abbreviated as ESR) in the high frequency region. Conventionally, plastic film capacitors, multilayer ceramic capacitors, and the like are frequently used as capacitors for high-frequency regions, but these have a relatively small capacity. As a capacitor having a large capacity and a low ESR, there is a solid electrolytic capacitor using an electronically conductive solid such as manganese dioxide or TCNQ complex salt as a cathode material. Here, TCNQ means 7,7,8,8-tetracyanoquinodimethane. A solid electrolytic capacitor using a conductive polymer such as polypyrrole, polythiophene, polyfuran or polyaniline as a cathode material is also promising. (For example, patent document 1).
Japanese Patent No. 3296724

  However, application fields of electronic devices in recent years are rapidly expanding with the progress of higher functionality, smaller size, and lighter weight. As a result, the components that make up electronic circuits have stricter usage environments, conditions, etc., and in particular, demands for improving withstand voltage have become stricter. Therefore, an object of the present invention is to provide an electrolytic capacitor using a conductive polymer as a cathode material and having high voltage resistance.

  The present invention relates to an electrolytic capacitor comprising a solid electrolyte layer made of a conductive polymer in a capacitor element in which an anode foil having a dielectric film formed thereon and a counter cathode foil are wound via a separator. Is a polymer of a polysynthetic monomer doped with sodium naphthalene sulfonate formalin condensate, and the capacitor element is impregnated with an electrolytic solution in addition to the solid electrolyte layer. .

  According to the said structure, deterioration of the oxide film in the process (polymerization process) of forming the solid electrolyte layer which consists of this electroconductive polymer by doping sodium naphthalene sulfonate formalin condensate in an electroconductive polymer is carried out. It is suppressed and the withstand voltage is improved.

  In the electrolytic capacitor according to the embodiment of the present invention, a wound capacitor element 7 as shown in FIG. 1 is used. The wound capacitor element is an anodized foil 1 obtained by subjecting a foil made of a valve metal such as aluminum, tantalum, niobium or titanium to an etching process for roughening and a chemical conversion process for forming a dielectric film. And the counter cathode foil 2 are wound up via a separator 3. Lead wires 51 and 52 are attached to the anodized foil 1 and the counter cathode foil 2 via lead tabs 61 and 62, respectively. Reference numeral 4 denotes a winding tape.

  The wound capacitor element is impregnated with a monomer that becomes a conductive polymer by oxidative polymerization such as pyrrole, and then the capacitor element is mixed with an oxidizing agent such as ammonium persulfate or sodium persulfate and naphthalenesulfonic acid as a doping agent. By immersing in an aqueous solution with a sodium formalin condensate, the monomer is oxidatively polymerized to form a conductive polymer. Note that the doping agent may be precipitated in the element by dissolving in water or a solvent in advance and drying.

  Finally, as shown in FIG. 2, the element 7 is housed in a bottomed cylindrical aluminum case 8, and a rubber packing 9 is attached to the opening, and after drawing and curling, the rated voltage A desired electrolytic capacitor is completed by performing an aging treatment at 125 ° C. for about 1 hour while applying C. Examples will be specifically described using an aluminum wound capacitor element having an outer diameter of 6.3 mm × H6 mm and a rating of 16 V-22 μF, according to the embodiment of the present invention, but the present invention is limited to these examples. Is not to be done.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After drying the element, it is impregnated with 2% aqueous solution of sodium naphthalene sulfonate formalin condensate and dried at 100 ° C. for 1 hour. The above element is impregnated with pyrrole and left at 50 ° C. for 15 minutes. Thereafter, the device is immersed in a 30% aqueous solution of ammonium persulfate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After drying the element, it is impregnated with 5% aqueous solution of sodium naphthalene sulfonate formalin condensate and dried at 100 ° C. for 1 hour. The above element is impregnated with pyrrole and left at 50 ° C. for 15 minutes. Thereafter, the device is immersed in a 30% aqueous solution of ammonium persulfate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with 50% aqueous solution of sodium naphthalene sulfonate formalin condensate and dried at 100 ° C. for 1 hour. The above element is impregnated with pyrrole and left at 50 ° C. for 15 minutes. Thereafter, the device is immersed in a 30% aqueous solution of ammonium persulfate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with pyrrole and allowed to stand at 50 ° C. for 15 minutes. Thereafter, the device is immersed in an aqueous solution of 30% ammonium persulfate and 2% sodium naphthalene sulfonate formalin condensate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with pyrrole and allowed to stand at 50 ° C. for 15 minutes. Thereafter, the device is immersed in an aqueous solution of 30% ammonium persulfate and 10% sodium naphthalene sulfonate formalin condensate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with pyrrole and allowed to stand at 50 ° C. for 15 minutes. Thereafter, the device is immersed in an aqueous solution of 30% ammonium persulfate and 30% sodium naphthalene sulfonate formalin condensate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with 50% aqueous solution of sodium naphthalene sulfonate formalin condensate and dried at 100 ° C. for 1 hour. Further, the element is impregnated with pyrrole and left at 50 ° C. for 15 minutes. Thereafter, the device is immersed in an aqueous solution of 30% ammonium persulfate and 30% sodium naphthalene sulfonate formalin condensate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

For comparison, a conventional manufacturing method will be described below.
(Conventional example 1)

Immerse a capacitor element with a rating of 16V-22μF in about half of a 0.1% phosphoric acid solution, apply the same voltage as the anode foil conversion voltage with the anode foil as plus and the bath as minus, and repair the defective part of the conversion film. To do. After the element is dried, it is impregnated with pyrrole and allowed to stand at 50 ° C. for 15 minutes. Thereafter, the device is immersed in a 30% aqueous solution of ammonium persulfate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.
(Conventional example 2)

  Capacitor element with a rating of 16V-22μF is immersed in a half of 0.1% ammonium adipate aqueous solution, the anode foil is positive, the tank is negative, the same voltage as the anode foil formation voltage is applied, and the defective portion of the conversion coating is removed. to repair. After the element is dried, it is impregnated with pyrrole and allowed to stand at 50 ° C. for 15 minutes. Thereafter, the device is immersed in an aqueous solution of 30% ammonium persulfate and 10% disodium benzenedisulfonate to form polypyrrole inside the device. Further, in order to remove the oxidant remaining in the element and unreacted pyrrole, it is washed with water and dried. Next, the element is impregnated with an electrolytic solution, assembled by the above-described method, and aged to obtain a finished product.

  Table 1 shows values of leakage current when several kinds of voltages are applied to the capacitors prototyped in Examples 1 to 7 and Conventional Examples 1 and 2. The ESR was measured at 100 kHz, and the capacitance was measured at 120 Hz.

  From Table 1, in the conventional examples 1 and 2, the value of the leakage current is high and the voltage leading to the short circuit is also low. On the other hand, it can be seen that in all of the examples, the leakage current is small and the withstand voltage is also improved.

  As described above, according to the method for manufacturing an electrolytic capacitor of the present invention, deterioration in the manufacturing process of the aluminum oxide film can be suppressed, and as a result, withstand voltage can be improved and leakage current can be reduced. .

It is a disassembled perspective view of the electrolytic capacitor element which concerns on the prior art and the Example of this invention. It is sectional drawing of the electrolytic capacitor element which concerns on the prior art and the Example of this invention.

Explanation of symbols

1 Anodized foil 2 Opposite cathode foil 3 Separator 4 Winding tape 7 Capacitor element 8 Case 9 Rubber packing 51 Lead wire 52 Lead wire 61 Lead tab 62 Lead tab

Claims (7)

In an electrolytic capacitor having a solid electrolyte layer made of a conductive polymer in a capacitor element in which an anode foil and a counter cathode foil formed with a dielectric film are wound through a separator,
The conductive polymer is a polymer of a polymerizable monomer doped with sodium naphthalene sulfonate formalin condensate,
An electrolytic capacitor, wherein the capacitor element is impregnated with an electrolytic solution in addition to the solid electrolyte layer.   2. The electrolytic capacitor according to claim 1, wherein the polymer is a polymer or copolymer of at least one monomer selected from pyrrole, thiophene, aniline, and derivatives thereof.   The electrolytic capacitor according to claim 2, wherein the polymer is polypyrrole. A first step of impregnating a capacitor element comprising an anode member formed with a dielectric film with an aqueous solution of sodium naphthalene sulfonate formalin condensate and then drying;
A second step of impregnating a polymerizable monomer into the capacitor element that has undergone the first step and leaving it to stand;
And a third step of immersing the capacitor element that has undergone the second step in an aqueous solution of an oxidizing agent.   The method for manufacturing an electrolytic capacitor according to claim 4, wherein the capacitor element that has undergone the third step is impregnated with a fourth step of impregnating the electrolytic solution. A first step of impregnating a sodium naphthalene sulfonate formalin condensate aqueous solution into a capacitor element including an anode member formed with a dielectric film, and then drying;
A second step of impregnating a polymerizable monomer into the capacitor element that has undergone the first step and leaving it to stand;
And a third step of immersing the capacitor element having undergone the second step in an aqueous solution of an oxidizing agent and a sodium naphthalene sulfonate formalin condensate.   The method of manufacturing an electrolytic capacitor according to claim 6, further comprising a fourth step of impregnating the electrolytic solution with the capacitor element that has undergone the third step.

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