JP3519906B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor using a conductive polymer as a cathode material.

[0002]

2. Description of the Related Art With the digitalization of electronic devices, capacitors used for them are required to be small, have a large capacity, and have a small equivalent series resistance (hereinafter abbreviated as ESR) in a high frequency region. There is.

Conventionally, plastic film capacitors, laminated ceramic capacitors and the like have been widely used as capacitors for the high frequency range, but these have a relatively small capacity.

As a small-sized, large-capacity, low-ESR capacitor, there is a solid electrolytic capacitor using an electron conductive solid such as manganese dioxide or TCNQ complex salt as a cathode material. Here, TCNQ means 7,7,8,8-tetracyanoquinodimethane. Further, a solid electrolytic capacitor using a conductive polymer such as polypyrrole, polythiophene, polyfuran, and polyaniline as a cathode material is also promising.

[0005]

In the conventional method for producing a solid electrolytic capacitor using the above-mentioned conductive polymer as a cathode material, a chemical conversion is performed on the surface of an anode sintered body or an anode foil made of a valve metal such as aluminum or tantalum. A coating, a conductive polymer layer, a graphite layer, and a silver paint layer are sequentially formed, and the cathode lead wire is connected thereto with a conductive adhesive or the like. This manufacturing method uses an anode foil with a conversion coating and a counter cathode foil. This is considerably complicated as compared with the usual method for producing an electrolytic capacitor in which a capacitor element formed by winding and with a separator is impregnated with an electrolytic solution. In addition, in the cathode extraction method as described above, E
SR becomes large.

On the other hand, the conductive polymer layer is formed by an electrolytic polymerization method or a vapor phase polymerization method, and the conductive polymer layer is formed in the wound type capacitor element by the electrolytic polymerization method or the vapor phase polymerization method. Is not easy. A manufacturing method in which a chemical conversion film and a conductive polymer layer are formed on the anode foil and then wound together with a counter cathode foil is conceivable, but it is difficult to wind the chemical conversion film and the conductive polymer layer without damaging them.

The present invention presents a new method for forming a conductive polymer layer in a capacitor element formed by winding an anodized foil and a counter cathode foil with a separator interposed therebetween, and is small in size, large in capacity and low in capacity. A solid electrolytic capacitor of ESR is provided.

[0008]

A method of manufacturing a solid electrolytic capacitor according to the present invention is a solid electrolytic capacitor in which a conductive polymer layer is formed in a capacitor element formed by winding an anodized foil and a counter cathode foil via a separator. In the method of manufacturing a capacitor, after the capacitor element is impregnated with a solution of an aniline salt such as aniline hydrochloride and aniline sulfate, the solvent component in the impregnating solution is evaporated to precipitate the aniline salt in the capacitor element, By immersing the element in an aqueous solution of an oxidizing agent such as ammonium persulfate or sodium persulfate, the aniline salt is oxidatively polymerized to form conductive polyaniline.

According to the above-mentioned production method of the present invention, a necessary and sufficient amount of polyaniline layer is formed in close contact with the anodized foil and the counter cathode foil in the capacitor element, and the polyaniline layer has excellent characteristics as a cathode material. Provided is a wound type solid electrolytic capacitor.

[0010]

In the method of manufacturing a solid electrolytic capacitor according to the embodiment of the present invention, a wound type capacitor element 7 as shown in FIG. 1 is used. The wound-type capacitor element is composed of an anodized foil 1 obtained by subjecting a foil made of a valve metal such as aluminum, tantalum, niobium or titanium to etching treatment for roughening and chemical conversion treatment for forming a dielectric film. , The opposite cathode foil 2 is wound up with the separator 3 in between. 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. 4 is a winding stop tape.

Then, a solution prepared by dissolving an aniline salt such as aniline hydrochloride or aniline sulfate in an organic solvent such as alcohol or water is prepared, the capacitor element is impregnated with the solution, and then the solution is impregnated in the impregnating solution using a drying furnace. The solvent component is evaporated to deposit an aniline salt in the capacitor element.

Then, the capacitor element is dipped in an aqueous solution of an oxidizing agent such as ammonium persulfate or sodium persulfate to oxidatively polymerize the aniline salt into polyaniline. About 3
After drying for 0 minutes, as shown in FIG. 2, it is housed in a bottomed cylindrical aluminum case 8, the opening is sealed with epoxy resin 9, and a rated voltage is applied at about 120 ° C. for about 1 hour. A desired solid electrolytic capacitor is completed by performing aging treatment.

Here, while using an aluminum winding type capacitor element having an outer diameter of φ6.3 mm × H7 mm and a rating of 6.3 V-33 μF, according to the embodiment of the present invention, Table 1
With respect to the solid electrolytic capacitors of Examples 1 to 11 which were prototyped under the conditions as shown in, a high temperature load test at 105 ° C. for 1000 hours was performed. Table 2 shows the measurement results of the capacitance: C before and after the high temperature load test, the tangent of the loss angle: tan δ, the leak current 15 seconds after applying the rated voltage: LC, the equivalent series resistance at 100 kHz: ESR. . Regarding C after the high temperature load test in Table 2, the change rate: ΔC / C value based on C before the test is shown.

[0014]

[Table 1]

[0015]

[Table 2]

As can be seen by comparing Table 1 and Table 2,
Before and after the high temperature load test of Examples 1 to 11 according to the present invention, LC was as small as about 1.2 μA or less and E
SR is small, about 150 mΩ or less.

More specifically, the ESR becomes particularly small when the concentration of the aniline salt solution with which the capacitor element is impregnated is 10 to 30 wt%.

Regarding the exterior of the capacitor, in the above embodiment, the capacitor element was housed in an aluminum case and sealed with a resin, but the exterior resin layer may be formed by a dipping method or the like.

[0019]

According to the present invention, since it is possible to form a conductive polyaniline layer inside a capacitor element including an anodized foil and a counter cathode foil, a chemical conversion film or an electrically conductive film during the manufacturing process can be formed. Damage to the polymer layer is suppressed,
A silver paint layer for drawing out the cathode is not necessary, and a small-sized, large-capacity, low-ESR solid electrolytic capacitor is provided.

Further, as the capacitor element used in the present invention, the existing wound type capacitor element for aluminum electrolytic capacitors can be diverted.
Costs can also be reduced by standardizing parts.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a capacitor element used in an embodiment of the present invention.

FIG. 2 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

1 Anodized foil 2 Opposite cathode foil 3 separator 4 winding stop tape 51 Anode lead wire 52 Cathode lead wire 61 Anode lead tab 62 cathode lead tab 7 Capacitor element 8 exterior case 9 Sealing resin

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01G 9/028

Claims (5)

(57) [Claims] 1. A method for producing a solid electrolytic capacitor in which a conductive polymer layer is formed in a capacitor element formed by winding an anodized foil and a counter cathode foil via a separator, wherein a solution of an aniline salt is applied to the capacitor element. After impregnation,
The solvent component in the impregnating solution is evaporated to deposit an aniline salt in the capacitor element, and the capacitor element is dipped in an aqueous solution of an oxidizing agent to oxidatively polymerize the aniline salt to form a conductive polyaniline. A method of manufacturing a solid electrolytic capacitor, comprising: 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein aniline hydrochloride or aniline sulfate is used as the aniline salt. 3. The method for producing a solid electrolytic capacitor according to claim 2, wherein ammonium persulfate or sodium persulfate is used as the oxidizing agent. 4. The concentration of the aniline salt solution is 5 to 30.
The solid electrolytic capacitor manufacturing method according to claim 3, wherein the solid electrolytic capacitor is used in a weight percentage. 5. The concentration of the oxidant aqueous solution is 10 to 50.
The method for producing a solid electrolytic capacitor according to claim 4, wherein the content is at least wt%.