JPS61271815A - 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] [Field of Industrial Application] The present invention relates to a solid electrolytic capacitor with good performance using a specific conductive polymer compound as a solid electrolyte. [Problems] Conventional solid electrolytic capacitors, such as aluminum electrolytic capacitors, have an aluminum oxide layer as a dielectric layer on an etched porous aluminum foil with a large specific surface area. The structure is impregnated with a liquid electrolyte, but the fact that this electrolyte is liquid causes problems such as leakage, which is not desirable.Therefore, attempts have been made to replace this conductive layer with a solid electrolyte. being done. 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. Mygan dioxide, which is formed by decomposition, has been used. However, the high heat required during this thermal decomposition and the N generated
Due to the oxidizing effect of Ox gas, etc., the metal oxide film on dielectric materials such as aluminum and tantalum is damaged, resulting in extremely large drawbacks such as a decrease in withstand voltage, an increase in leakage current, and a deterioration of dielectric properties. 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 described in Japanese Patent Application Laid-open No. 52-79255,
7,8.8-tetracyanoquinodimethane (TCNQ)
7. A solid electrolytic capacitor containing a conductive polymer composition containing a complex salt as a solid electrolyte, Nn-globylisoquinoline described in JP-A-58-17609;
Solid electrolytic capacitors containing a complex salt of 7,8,8-tetracyanoquinodimethane as a solid electrolyte are known. These TCNQ complex salt compounds have poor adhesion to the anodic oxide film and insufficient electrical conductivity of 10 to 10 S-, so 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.

[Failure to solve the problem]

An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a solid electrolytic capacitor in which an organic semiconductor having high conductivity and good adhesion to a dielectric film is used as a solid electrolyte.

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 uses a conductive polymer compound having a repeating unit represented by the following formula (wherein 2 is a quinone, R is hydrogen, and 9 is an alkyl group having 6 or less carbon atoms) as a solid electrolyte. The present invention relates to a solid electrolytic capacitor characterized by:

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). Typical examples of the compounds include chloranil salt of I-lysophenylamine, quinone salt of polydiphenylamine, naphthoquinone salt of I-lysophenylamine, and 2-cyanodichloroquinone salt of /17 zophenylamine. The method for producing these conductive polymer compounds is not particularly limited. For example, in the case of chloranil salt of polydiphenylamine, diphenylamine hydrochloride is polymerized using an oxidation catalyst, and then the obtained polydiphenylamine hydrochloride is It is obtained by adding lithium salt of chloranil to an aqueous solution of chloranil and causing a reaction.

The above conductive polymer compound itself has a 10-2 to 10
It exhibits a conductivity of 5-m.

In the present invention, conductive polymer compounds prepared by doping various conventionally known dosents 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, mental, 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 is oxidized in a solution of ammonium borate to form a thin dielectric layer on the metal 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 enters into the pores. This figure schematically shows a case where metal foil is used in a solid electrolytic capacitor that is a specific example of the present invention.

〔Effect of the invention〕

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 oxide semiconductors or organic semiconductors.

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

■ Since the electrolyte layer can be formed without high-temperature heating, there is no damage to the oxide film on the anode.
There is no need to perform reconstitution. 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 capacity and 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-F, there is no need to provide a conductive layer such as graphite.

This simplifies the process and is advantageous in terms of cost.

〔Example〕

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%)
Using this as an anode, 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 m/g. 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, 0.11 mol of polydiphenylamine hydrochloride obtained by polymerizing nophenylamine hydrochloride was added to a reaction vessel in 201 mol of water.
A solution containing 11IVC is charged, and lithium chloranil, which is a reaction product of lithium iodide and chloranil, is added to the solution.
．． A 1 mol aqueous solution was mixed and reacted at 60°C for 3 hours. After the reaction was completed, the mixture was allowed to stand at 0°C to isolate crystals. The crystals were thoroughly washed with water and then dried under reduced pressure. The conductivity of the obtained chloranil salt of pridiphenylamine is 0.9 S-c
It was m-'.

2 g of the chloranil salt of polydiphenylamine was dissolved in 100 R/ml of acetone and applied to the dielectric layer, and vacuum degassing was repeated to sufficiently fill the pores with the solution, and then the acetone was dried up. A solid electrolytic capacitor was fabricated using aluminum foil as the cathode and sealing it with resin, and using chloranil salt of polydiphenylamine as the solid electrolyte layer.

Example 2 A solid electrolytic capacitor was produced in the same manner as in Example 1, except that quinone salt of terinophenylamine produced from lithium quinone and polydiphenylamine hydrochloride was used instead of chloranil salt of polydiphenylamine. did. The conductivity of the quinone salt of polydiphenylamine used was o, oss-α.

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

Example 3 After anodic oxidation of a tantalum powder sintered body in an aqueous phosphoric acid solution to form a dielectric film on the sintered body, the mental element was immersed in a seventone solution of chloranil salt of polydiphenylamine. and dried.

This dipping and drying operation was repeated. 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.

Table Note: As is clear from the value at 25V, the solid electrolytic capacitor using a conductive polymer compound as an electrolyte according to the present invention has a higher
It is possible to create a solid electrolytic capacitor with low dielectric loss leakage current, high rated voltage, and high withstand voltage. It was,
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 is a sectional view showing a specific example of a solid electrolytic capacitor according to the present invention. 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] A repeating unit represented by the following formula ▲ Numerical formulas, chemical formulas, tables, etc.▼ (1) (In the formula, Z is a quinone, and R is hydrogen or an alkyl group having 6 or less carbon atoms.) A solid electrolytic capacitor characterized in that a solid electrolyte is a conductive polymer compound having the following properties.