JP2002343684A - Solid electrolytic capacitors - Google Patents

Abstract

(57) [Problem] To provide a solid electrolyte capacitor having a small leakage current. SOLUTION: An insulating resin material 9 in which an insulating solid is mixed is formed by electrodeposition at a defective portion on a dielectric film 3 formed on a valve metal porous body 2 to insulate the insulating material, thereby obtaining electrical characteristics. And a solid electrolytic capacitor having excellent

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor used for electronic circuits of electric equipment and electronic equipment.

[0002]

2. Description of the Related Art As a conventional technique, as shown in FIG. 2, a dielectric film 13 is applied to a valve metal porous body 12 on a valve metal foil 11.
A conductive polymer film is formed on the dielectric film 13 to form a solid electrolyte layer 14. On the solid electrolyte layer 14, a current collector layer including a carbon layer 15 and a silver paste layer 16 is formed. An insulating separation layer 20 is provided in advance between the current collector layer and the lead-out portion of the valve metal foil 11, and the whole is molded with an exterior resin material 17. A solid electrolytic capacitor having a structure in which one external electrode 18a electrically connected to the foil 11 is provided and the other external electrode 18b electrically connected to the current collector layer at the other end is provided.

In the production of this solid electrolytic capacitor,
When the oxide film cannot be completely formed on the valve metal porous body 12 by the chemical formation, or the dielectric film 13 is damaged by the stress at the time of manufacturing, and the solid electrolyte layer 14 is formed thereon, the leakage current is increased. In some cases, the capacitor characteristics were impaired, such as an increase or a decrease in withstand voltage.

[0004]

As described above, in the conventional solid electrolytic capacitor, a dielectric film 13 is formed on a valve metal porous body 12, and a conductive polymer film is formed on the dielectric film 13. In a solid electrolytic capacitor having a structure in which the solid electrolyte layer 14 is used, the leakage current increases due to the fact that the insulation defect portion of the dielectric film 13 is in direct contact with the solid electrolyte layer 14 made of a conductive polymer formed by polymerization. In order to prevent the problem of lowering the withstand voltage, the portion where the dielectric film 13 is damaged is replaced with a part of the dielectric film 13
However, productivity was poor.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a solid electrolytic capacitor having excellent productivity, low leakage current and high withstand voltage.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to form a resin material in which an insulating solid is mixed in an insulating defect portion of a dielectric film by electrodeposition, thereby obtaining excellent electric characteristics. Solid electrolytic capacitor.

According to a first aspect of the present invention, a dielectric film is provided on the surface of a valve metal porous body, and a resin material in which an insulating solid is mixed in a defective portion of the dielectric film is formed by electrodeposition. The present invention relates to a solid electrolytic capacitor formed and provided with a solid electrolyte layer on the dielectric film and a current collector layer on the solid electrolyte, and to reduce a leakage current because a defective portion of the dielectric film is repaired. Can be.

According to a second aspect of the present invention, there is provided the solid electrolytic capacitor according to the first aspect, wherein the insulating solid material is a filler, and a resin which reliably fills a defect portion of the dielectric film with a defect. A material can be formed, and the withstand voltage can be increased.

According to a third aspect of the present invention, there is provided the solid electrolytic capacitor according to the second aspect, wherein a filler having a size of 1 μm or less is used. And leakage current can be reduced.

According to a fourth aspect of the present invention, there is provided the solid electrolytic capacitor according to the second aspect, wherein a filler mixed with 0.1 to 15 wt% is used. Because there is no, the capacity can be drawn out.

According to a fifth aspect of the present invention, there is provided the solid electrolytic capacitor according to the first aspect, wherein the insulating solid material is a microgel. Can be formed and can be made strong against external stress.

According to a sixth aspect of the present invention, there is provided a solid electrolytic capacitor according to the fifth aspect, wherein a microgel having a size of 10 μm or less is used. A material can be formed, and leakage current can be reduced.

The invention according to claim 7 of the present invention relates to the solid electrolytic capacitor according to claim 5, wherein a microgel mixed with 5 to 15 wt% is used, and a uniform resin material can be formed. The withstand voltage can be increased.

According to an eighth aspect of the present invention, the resin material is formed by electrodepositing a defective portion of the dielectric film with a voltage lower than the formation voltage for forming the dielectric film. Since the resin material is formed only at a portion where a current leaks at a voltage lower than the formation voltage, the resin material can be formed at a defective portion without affecting the capacity.

According to a ninth aspect of the present invention, there is provided the solid electrolytic capacitor according to the first aspect, wherein the valve metal porous body is formed on at least one surface of the valve metal foil. Easy configuration.

The tenth aspect of the present invention relates to the solid electrolytic capacitor according to the first aspect, wherein the solid electrolyte layer is formed of a functional polymer, and the ESR can be reduced.

According to an eleventh aspect of the present invention, the solid electrolyte layer comprising a functional polymer is formed by laminating a solid electrolyte layer by electrolytic polymerization on a solid electrolyte layer by chemical polymerization. It relates to the solid electrolytic capacitor described above, and can have excellent high-frequency characteristics.

According to a twelfth aspect of the present invention, there is provided a solid electrolytic capacitor according to the first aspect, wherein the resin material contains any one of chemical resistance, water repellency and dielectric properties. Performance, mass productivity, or reliability can be improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with specific examples.

(Embodiment 1) A solid electrolytic capacitor according to Embodiment 1 of the present invention will be described below with reference to FIG.

A valve metal porous body 2 (3.4 × 5.3 × 0.2 mm) made of a sheet-type sintered body of tantalum powder formed on a valve metal foil 1 such as tantalum is placed in a phosphoric acid solution. (12 V) to form a tantalum oxide film layer as a dielectric film 3 on the surface of the valve metal porous body 2. Immersed in an electrodeposition solution of epoxy-acrylic resin containing, and electrodeposited at 10 V for 2 minutes, then washed with water, pre-dried at 80 ° C, and fully cured at 180 ° C to obtain an epoxy-acrylic resin material 9 Was formed on the defective portion of the dielectric film 3, a silicone resin was applied to the boundary between the portion where the solid electrolyte layer was formed and the portion used as the electrode portion, and was cured at 150 ° C. for 1 hour to form the insulating separation layer 10.

Thereafter, it is immersed in a pyrrole solution containing pyrrole, water and ethylene glycol at a weight ratio of 1: 15: 1, and ferric sulfate, water and ethylene glycol at a weight ratio of 1: 1.5: A polypyrrole film was formed by chemical oxidative polymerization by immersion in an oxidizing agent solution containing 1.8 parts. Next, the solid electrolyte layer 4 was formed by immersion in a thiophene solution containing thiophene, ferric p-toluenesulfonate and butanol at a weight ratio of 1: 0.1: 0.2. Further, a carbon layer 5 and a silver paste layer 6 are sequentially formed as a current collector layer on the solid electrolyte layer 4, a counter electrode is taken out from a part thereof, and then molded with an exterior resin material 7 such as epoxy. One external electrode 8a electrically connected to the valve metal foil 1 is formed at one end of the material, and the other external electrode 8b electrically connected to the silver paste layer 6 of the current collector layer is formed at the other end. Thus, a solid electrolytic capacitor was completed.

The initial characteristics of the obtained solid electrolytic capacitor are shown in Table 1.

(Embodiment 2) In the same manner as in Embodiment 1, a 1 μm or less filler of titanium oxide as an insulating solid is added to the defective portion of the dielectric film 3 in the same anode body as in Embodiment 1. An insulating resin material 9 of an epoxy-acrylic resin containing 0.5 wt% (containing 10 wt% as a microgel having an acrylic resin of 10 μm or less) was formed. Further, after the insulating resin material 9 of epoxy-acrylic resin is formed, a silicone resin is applied to the boundary between the portion where the solid electrolyte layer 4 is formed and the portion used as the electrode portion 1 and cured at 150 ° C. for 1 hour to insulate A separation layer 10 was formed.

Next, it is immersed in a solution of thiophene, iron (III) p-toluenesulfonate and butanol to form a precoat layer. A stainless wire was lightly contacted with the precoat layer, and a constant voltage of 3 V was applied to the stainless steel plate as an electrode to perform electrolytic polymerization for 30 minutes to form a solid electrolyte layer 4. After completion of the reaction, a solid electrolytic capacitor was completed in the same procedure as in the first embodiment.

The initial characteristics of the obtained solid electrolytic capacitor are shown in Table 1.

Comparative Example A device having an insulating separation layer was formed in the same procedure as in the second embodiment except that the insulating resin material of epoxy-acrylic resin was not formed at the defective portion of the dielectric film. Next, repair formation was performed in a phosphoric acid solution to repair defective portions of the dielectric film. Thereafter, a solid electrolyte layer, a current collector layer, an exterior resin material, and external electrodes were formed in the same procedure as in Embodiment 2 to complete a solid electrolytic capacitor.

The initial characteristics of the obtained solid electrolytic capacitor are shown in Table 1. The solid electrolytic capacitor of the comparative example has a large leakage current and a low withstand voltage.

[0029]

[Table 1]

In the above embodiment, the solid electrolyte layer 4
Is formed by using a chemical polymerization method or a solid electrolyte layer synthesized by a chemical polymerization method as a precoat layer, and performing electrolytic polymerization on the precoat layer. The solid electrolyte layer 4 formed by electrolytic polymerization is not particularly limited, but is preferably made of pyrrole, thiophene, aniline, or a material having a dielectric unit thereof as a repeating unit from the viewpoint of easiness of the polymerization reaction. Any of chemically oxidized and polymerized polypyrrole or polyaniline, or polythiophene, or any of their derivatives is desirable, and further, ponyaniline,
Any combination of polythiophene and polypyrrole may be used.

Further, if the filler, which is an insulating solid material mixed as an insulating resin material 9 formed at a defective portion of the dielectric film 3, is 1 μm or more, it is difficult to mix with other resin materials, and If the mixing amount is less than 0.1 wt%, the purpose of mixing cannot be achieved, and if it is more than 15 wt%, electrodeposition cannot be performed.

Further, when microgel is used as the insulating solid, it is preferably 10 μm or less, more preferably 10 μm.
m or more, the resin material 9 cannot be reliably formed at the defective portion. If the mixing amount is 5 wt% or less, the purpose of mixing cannot be achieved.
Formation becomes difficult.

Further, as shown in the second embodiment, a filler and a microgel can be used in combination.

Further, as the insulating resin material 9,
Based on an acrylic resin, a mixture of an epoxy resin or a fluorine resin having excellent chemical resistance and a fluorine resin having water repellency or dielectric properties can be used.

[0035]

As described above, the present invention reduces the leakage current by forming an insulating resin material mixed with an insulating solid material at the defective portion of the dielectric film of the valve metal porous body by electrodeposition. A small and high withstand voltage solid electrolytic capacitor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a solid electrolytic capacitor of the present invention.

FIG. 2 is a cross-sectional view of a conventional solid electrolytic capacitor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 valve metal foil 2 valve metal porous body 3 dielectric coating 4 solid electrolyte layer 5 carbon layer 6 silver paste layer 7 exterior resin material 8a, 8b external electrode 9 insulating resin material 10 insulating separation layer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yuji Mido 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] A dielectric film is provided on a surface of a valve metal porous body, and a resin material mixed with an insulating solid is formed by electrodeposition on a defective portion of the dielectric film, and a solid material is formed on the dielectric film. A solid electrolytic capacitor provided with an electrolyte layer and a current collector layer on the solid electrolyte. 2. The insulating solid material is a filler.
3. The solid electrolytic capacitor according to item 1. 3. The solid electrolytic capacitor according to claim 2, wherein a filler having a size of 1 μm or less is used. 4. The solid electrolytic capacitor according to claim 2, wherein a filler mixed with 0.1 to 15% by weight is used. 5. The solid electrolytic capacitor according to claim 1, wherein the insulating solid is a microgel. 6. The solid electrolytic capacitor according to claim 5, wherein a microgel having a size of 10 μm or less is used. 7. The solid electrolytic capacitor according to claim 5, wherein a microgel mixed with 5 to 15 wt% is used. 8. The solid electrolytic capacitor according to claim 1, wherein the defective portion of the dielectric film is formed by electrodeposition with a voltage lower than the formation voltage for forming the dielectric film. 9. The solid electrolytic capacitor according to claim 1, wherein the valve metal porous body is formed on at least one surface of a valve metal foil. 10. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is formed of a functional polymer. 11. The solid electrolytic capacitor according to claim 10, wherein the solid electrolyte layer made of a functional polymer is formed by laminating a solid electrolyte layer formed by electrolytic polymerization on a solid electrolyte layer formed by chemical polymerization. 12. The solid electrolytic capacitor according to claim 1, wherein the resin material contains one of chemical resistance, water repellency, and dielectric properties.