JPS6185813A - Solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid electrolytic capacitor with good performance when used as a solute.

Conventional solid electrolytic capacitors, such as aluminum electrolytic capacitors, have an aluminum oxide layer as a dielectric layer placed on an etched porous aluminum foil with a large specific surface area, and a liquid electrolyte is applied to the electrolytic paper between the cathode foil and the etched porous aluminum foil. Although it has an impregnated structure, it is not desirable for this electrolyte to be in liquid form and cause problems such as leakage.
Therefore, attempts have been made to replace the conductive layer with a solid electrolyte. These solid electrolytic capacitors have a structure in which a solid electrolyte is attached to a film-forming metal such as aluminum or tantalum that has an anodized film. Manganese dioxide, which is formed by decomposition, is used. However, the high heat required during this thermal decomposition and the N generated
K, such as the oxidizing effect of Ox gas, can damage the oxide film of metals such as aluminum and tantalum, which are dielectrics, resulting in extremely serious drawbacks such as lower withstand voltage, large leakage current, and deterioration of dielectric properties. There is.

In addition, a process called reconstitution is also necessary.

In order to compensate for these drawbacks, attempts have been made to form a solid electrolyte layer without applying high heat, that is, to use a highly conductive organic semiconductor material as the solid electrolyte. As an example, 7
, 7,8.8-tetra/anoquinotumethane (TCNQ
) A solid electrolytic capacitor containing a conductive polymer composition containing a complex salt as a solid electrolyte, Nn-glopylisoquino') described in JP-A-58-17609:
A solid electrolytic capacitor containing a complex salt consisting of L7tL8-tetrananoquinotumethane as a solid electrolyte is known. These TCNQCN compounds have poor adhesion to the anodic oxide film, and have conductive dust of 10-3 to 10-23-c.
m-', which is insufficient, the capacitance value of the capacitor is small and the dielectric loss is large. Furthermore, thermal stability over time is poor and reliability is low.

An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a solid electrolytic capacitor using an organic semiconductor as a solid electrolyte, which has high conductive dust and has good adhesion to a dielectric film.

It has been found that this objective can be achieved by using a specific conductive polymer compound as a solid electrolyte.

That is, the present invention relates to a solid electrolytic capacitor characterized in that a tetrafunctional polymer compound having a repeating unit represented by the following formula (wherein 2 is a quinone) is used as a solid electrolyte.

The solid electrolytic capacitor obtained by the present invention has significantly superior performance in terms of capacity, dielectric loss, and stability over time compared to conventional solid electrolytic capacitors using inorganic or organic semiconductors. .

Furthermore, the solid electrolytic capacitor of the present invention has the following advantages compared to conventionally known solid electrolytic capacitors.

(2) Since the electrolyte layer can be formed without high-temperature heating, there is no damage to the oxidized wL film of the anode, and there is no need to perform anodic oxidation (reformation) for repair. Therefore, the rated voltage can be increased several times compared to conventional capacitors, and the shape can be made smaller to obtain a capacitor with the same rated voltage.

■Low leakage current.

■ Capacitors with high withstand voltage can be manufactured.

(2) Since the conductivity of the electrolyte is sufficiently high at 10 to 10 S-z, there is no need to provide a conductive layer such as graphite. This simplifies the process and is advantageous in terms of cost.

The electrolyte used in the solid electrolytic capacitor of the present invention is a conductive polymer compound having a repeating unit represented by the above formula (1).

Representative examples of conductive polymer compounds having repeating units represented by formula (1) include 1. IIJ pyridinium chloranyl, polypyrinonium quinone, polypyrinonium naphthoquinone, noripyrinonium zochloroone anoquinone, and the like. The method for producing these conductive polymer compounds is not particularly limited. For example, in the case of noripyrinonium chloranil, polypyridinium chloride or polypyrinonium obtained by thermal polymerization from 4-chloropyrinone or 4-bromopyrinone is used. It is obtained by adding lithium salt of chloranil to an aqueous solution of bromyl and causing a reaction.

The above conductive polymer compound itself is 10-2 to 1O
8-hole conductivity.

In the present invention, conductive polymer compounds doped with various conventionally known dosing agents can also be used as the electrolyte. The doping method for doping may be either chemical doping or electrochemical doping.

For the anode of the solid capacitor in the present invention, a metal foil of aluminum, tantalum, niobium, or the like, or a sintered body of metal powder thereof is used. In the case of metal foil, the surface is etched to create pores. Metal foil or sintered body is
For example, the electrode oxidizes gold in ammonium borate solution.
A thin layer of dielectric is formed on the foil or sintered body.

The conductive polymer compound in the present invention comes into contact with this dielectric thin layer, and a portion of the conductive polymer compound penetrates into the pores. Figure 1 schematically shows a case where metal foil is used in a solid electrolytic capacitor which is a specific example of the present invention.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Aluminum foil with a thickness of 100 μm (purity 99.99 cm)
was used as an anode, and the surface of the foil was electrochemically etched using alternating direct current and alternating current to obtain a porous aluminum foil with an average pore diameter of 2 μm and a specific surface area of 12 mlfl. The etched aluminum foil was then immersed in an ammonium borate solution, and a thin dielectric layer was electrochemically formed on the aluminum foil in the solution.

On the other hand, 2410.1 mol of polybirizonium chrome obtained by thermal polymerization of Vc4-chloropyridine in a reaction vessel was added to 2011 mol of water.
A solution containing 0.1 mole of lithium chloranil, which is a reaction product of lithium and chloranil, was mixed therewith and reacted at 60° C. for 10 hours. After the reaction was completed, the mixture was left at 0°C. The obtained polypyridinium chloranil crystals were thoroughly washed with water and then dried under reduced pressure. Obtained. 41J Pyrinonium chloranyl conductive dust, 0
．． 48-H-'.

Add 2 g of this polypyridinium chloranil to 100 ml of acetone.
The solution was dissolved in #ll and applied to the dielectric layer, and the vacuum degassing was repeated to sufficiently fill the pores with the solution, followed by drying up with acetone. A solid electrolytic capacitor with polypyridinium chloranil as the solid electrolyte layer was created by using aluminum foil as the cathode and sealing it with resin.

Example 2 A solid electrolytic capacitor was produced in the same manner as in Example 1, except that polypyrinonium quinone produced from lithium quinone and polypyridinium chloranyl was used instead of polypyridinium chloranyl. The electrical conductivity of the holykirinonium quinone used was 0. I
It was S-α.

Comparative Example 1 Using an aluminum foil having the same dielectric layer as in Example 1, a solid electrolytic capacitor was fabricated using conventional manganese dioxide as a solid electrolyte and aluminum foil as a heel cathode.

Example 3 A sintered body of tantalum powder was anodized in an aqueous phosphoric acid solution to form a dielectric film on the sintered body, and then a tantalum element was immersed in an acetone solution of polypyridinium chloranyl and dried. Ta. This immersion drying operation was repeated three times. A solid electrolyte layer was formed by heating in this manner, and then it was surrounded by a silver case to serve as a cathode, and the joint with the anode was sealed with resin to produce a solid electrolytic capacitor.

Comparative Example 2 A solid electrolytic capacitor was produced using a tantalum powder sintered body made of a conventional manganese dioxide solid electrolyte.

A comparison of the characteristics of the solid electrolytic capacitors of the above examples and comparative examples is shown in the table.

Note: *...As is clear from the value table at 25V, 1) The solid electrolytic capacitor using the conductive polymer compound according to the present invention as the electrolyte + [solution] is different from the conventional solid electrolytic capacitor using manganese dioxide as the electrolyte. In comparison, it is possible to create a solid electrolytic capacitor with low dielectric loss leakage current, high rated voltage, and high withstand voltage. Further, the value of capacity x rated voltage of the solid electrolytic capacitor according to the present invention is larger than that of a solid electrolytic capacitor using manganese dioxide, and a large capacity can be obtained with the same shape.

[Brief explanation of the drawing]

The figure shows an example of a solid electrolytic capacitor 15' according to the present invention.
It is a sectional view showing llk. DESCRIPTION OF SYMBOLS 1... Anode lead wire, 2... Anode, 3... Oxide film, 4... Cathode, 5... Cathode lead wire, 6... Conductive polymer compound, 7... Resin .

Claims (1)

[Claims] The solid electrolyte is a conductive polymer compound having a repeating unit represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, Z is a quinone) solid electrolytic capacitor.