JPH03163815A - Manufacture of aluminum sintered body solid-state 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 [Objective of the Invention (1) (Industrial Field of Application) The present invention relates to a method for producing an aluminum sintered solid electrolytic capacitor using a conductive polypyrrole film as a solid electrolyte.

(Prior art) A conductive polymer film formed by chemical oxidation polymerization and a conductive polymer film formed by electrolytic polymerization are sequentially formed on the surface of a film-forming metal on which a dielectric oxide film is formed. Solid electrolytic capacitors have been proposed in which a carbon layer and a conductive coating are formed on a polymerized conductive polymer film. Compared to conventional solid electrolytic capacitors, this capacitor has features such as larger capacitance and better temperature and frequency characteristics. Development of a method is desired.

(Problems to be Solved by the Invention) The object of the present invention is to provide a solid electrolytic capacitor having a structure in which a conductive polymer film is formed as a solid electrolyte on the surface of an aluminum sintered body on which a dielectric oxide film is formed. An object of the present invention is to provide a method for manufacturing a capacitor that has the best electrical characteristics and is economically inexpensive.

-31 [Structural structure of the invention 1 (Means for solving the problem) As a result of intensive research, the present inventors have come to invent a method for manufacturing an aluminum sintered solid electrolytic capacitor that can achieve the above object. Ta.

That is, an aluminum sintered element with a dielectric oxide film formed on its surface is immersed in an aqueous solution containing hydrogen peroxide and an acid, and then immersed in an ice-insoluble solvent solution containing pyrrole monomer or virol monomer. A polypyrrole film is formed by chemical oxidation polymerization on the dielectric oxide film by dipping,
Next, the element is immersed in an electrolytic solution containing a pyrrole monomer and a para-toluene sulfonate to perform electrolytic polymerization, thereby forming a polypyrrole film by electrolytic polymerization on a polypyrrole film by chemical oxidation polymerization. This is a method for manufacturing a sintered solid electrolytic capacitor.

Next, the present invention will be explained in more detail.

The aluminum sintered element from which the anode lead has been taken out is anodized in a chemical solution to form a dielectric oxide film on the aluminum metal surface. This element is immersed in an aqueous solution containing hydrogen peroxide and an acid. Hydrogen peroxide concentration is 0. 0 5 IIio, I/1'~15. Omol
/i', preferably 0.lmol/1 to 1-0. 0
If the concentration is adjusted to mol/1, and the concentration is too low, chemical oxidative polymerization is difficult to occur.On the other hand, if the concentration is high, it can be used, but it is inconvenient to handle because it is a strong oxidizing agent. Acid concentration is 0.005mol/1-4. 0mol/1
, preferably 0,Olmol/l-2,OIIlol/
Set WA to 1. If the concentration is too low, chemical oxidative polymerization is difficult to occur, and conversely, if the concentration is too high, it is a highly concentrated acid and is inconvenient to handle.

As the acid of the present invention, organic acids such as adipic acid and acetic acid, and inorganic acids such as sulfuric acid and phosphoric acid can be used.
Sulfuric acid is preferred because it is inexpensive. The immersion time is approximately 5 to 30 minutes, and the immersion method may be immersion under normal pressure or immersion under reduced pressure.

Next, the element is quickly immersed in a pyrrole monomer or a water-insoluble solvent solution containing the pyrrole monomer to cause a chemical oxidative polymerization reaction to form a polypyrrole film by chemical oxidative polymerization on the dielectric oxide film.

The pyrrole monomer concentration of the solution is 10 vol% or more, preferably 25 vol% or more.

If the pyrrole monomer concentration is too low, the obtained capacitor characteristics may be slightly deteriorated. As the water-insoluble ill, aromatic organic solvents and ether organic solvents such as benzene, toluene, and xylene can be used. In this chemical oxidation polymerization reaction, if a water-soluble solvent is used instead of a water-insoluble solvent, the oxidizing agent aqueous solution immersed in the sintered body will diffuse into the pyrrole solution, making it impossible to form a good chemical oxidation polymerization film. Sometimes. The immersion reaction time is 5 minutes to 30 minutes, and the immersion method may be under normal pressure or reduced pressure. Furthermore, instead of immersion, the element can be exposed to pyrrole vapor to carry out chemical oxidative polymerization in the gas phase.

Furthermore, the chemical oxidative polymerization can be repeated two or more times.

After the reaction, the element is taken out, washed, and dried to obtain element -6- in which a polypyrrole film formed by chemical oxidative polymerization is formed.

In the chemical oxidative polymerization process of the present invention using hydrogen peroxide as an oxidizing agent, the element on which the dielectric oxide film has been formed is first immersed in an aqueous solution containing hydrogen peroxide and an acid, and then
It is characterized by immersion in a pyrrole monomer or a water-insoluble solvent solution containing the pyrrole monomer. If this operation is reversed, the resulting capacitor may be unsatisfactory in capacitance.

Next, the device is immersed in an electrolytic solution containing pyrrole monomer and balatoluenesulfonate as a supporting electrolyte,
A conductor is brought into contact with a part of the polypyrrole film formed by chemical oxidation polymerization and used as an anode, and electrolytic polymerization is performed between the part and the external cathode to form a polypyrrole film formed by electrolytic polymerization on the polypyrrole film formed by chemical oxidation polymerization.

The concentration of pyrrole monomer in the electrolyte is 0.005 mol/
1 to 3.0 mol/n, preferably 0.01 mol/n
1~1.0Io01/l! It is. In addition, supporting electrolyte balatoluenesulfonate WjkO, O
O5mol-7-/1-3. 1) mol/l, preferably 0. 0
1 mol/1! ~1, Omol/t! It is. In either case, if the concentration is too low, the electrical characteristics of the resulting capacitor tend to deteriorate, and conversely, the higher the concentration, the more the electrical characteristics improve, or even if the concentration is too high, the effect of improving the electrical characteristics is small.

As the cation of paratoluenesulfonate, an alkali metal cation or a quaternary ammonium cation is used.

In addition to water, as a solvent for the electrolytic solution, organic solvents such as acetonitrile can be used alone or in a mixture of water and an organic solvent.

In addition, for the purpose of reducing leakage current, a step of reconstitution in a chemical solution may be used after chemical oxidative polymerization.

The element on which the conductive polypyrrole film has been formed in this manner is washed and dried, then immersed in coroiglucarbon and dried to form a carbon layer on the surface. Furthermore, a conductive coating film is formed using a conductive paste on top of the coating film, and a lead wire for drawing out the cathode is connected to a part of the coating film.

-8 - As the conductive paste, silver paste, copper paste, aluminum paste, nickel paste, etc. can be used. The aluminum sintered capacitor element constructed as described above is packaged with a resin mold, a resin case, or a metal case to obtain an aluminum sintered solid electrolytic capacitor.

(Example) Hereinafter, the present invention will be specifically explained using examples.

Example 1 An aluminum sintered element from which an anode lead was taken out was anodized in a chemical solution at 100 V to form a dielectric oxide film.

The element was treated with 6 mol/l of hydrogen peroxide and 0.3 mo of sulfuric acid.
It was immersed in an aqueous solution containing 1/1 for 10 minutes at room temperature.

Next, the element was taken out and subsequently immersed in a pyrrole monomer stock solution for 15 minutes to perform chemical oxidation polymerization in the liquid phase. After washing and drying, a black polypyrrole film formed by chemical oxidation polymerization was formed on the dielectric oxide film.

-9- The device was then reactivated at 70V in a chemical solution.

After that, 0.3 mol/0.3 mol of pyrrole monomer was used as an electrolyte.
1. Tetraethylammonium paratoluenesulfonic acid 0.3+nol/1! An acetonitrile solution containing the electrolyte was placed in a stainless steel tank, and the device was immersed in the electrolyte. A part of the polypyrrole film formed on the dielectric oxide film that undergoes chemical oxidative polymerization is brought into contact with a stainless steel wire as an anode, and a stainless steel tank is used as a cathode to electrolyze for 3 () minutes at a constant current of 1IIIA, resulting in chemical oxidative polymerization. A polypyrrole film was formed on the polypyrrole film by electrolytic polymerization. After removing from the electrolyte, washing and drying, the element is immersed in colloidal carbon, dried, coated with silver paste, attached with a cathode lead, and molded with epoxy resin to give a rated voltage of 25 V and a nominal capacitance of 1.0 μF. An aluminum sintered solid electrolytic capacitor was obtained. Capacitance at 120Hz, tangent of loss angle (tan δ) and 100KH of a successful capacitor
The equivalent series resistance (ESR) at z is shown in Table 1.

2 L -l〇 Hydrogen peroxide concentration 0.05 mol/j (Example 2), 0
．． 1mo1/j! (Example 3), 10 mol/n (Example 4), and 13 mol/n (Example 5) were used to obtain aluminum sintered solid electrolytic capacitors according to the procedure of Example 1. The most successful electrical characteristics of capacitors
Shown in the table.

Table 1-11- Examples 6 to 9 Sulfuric acid concentration is 0. 0 0 5 mol/1 (Example 6),
0. (1 1 mol/1 (Example 7), 2.0 m
ol/p (Example 8), 3.0 mol/β (Example 9)
An aluminum sintered solid electrolytic capacitor was obtained according to the procedure of Example 1 except for the following. Table 1 shows the electrical characteristics of the successful capacitor.

When the hydrogen peroxide concentration is less than 0.1 mol/17 and when the sulfuric acid concentration is less than 0.1 mol/p and ζ1, chemical polymerization is difficult to occur and the capacitor characteristics deteriorate slightly, but the capacitor satisfies the characteristics sufficiently.

Examples 10/-12 The pyrrole monomer stock solution used in chemical polymerization was made into a toluene solution of pyrrole monomer, and the pyrrole monomer concentration was 10 vol% (Example 10) and 25 vol% (Example 11).
), Example 1 except that it was 80 vol% (Example 12)
According to. Table 2 shows the electrical characteristics of the successful capacitor.

-12- If the pyrrole concentration is less than 25 vol%, the capacitor characteristics will be slightly degraded, but it can be used satisfactorily as a capacitor.

Examples 13 to 20 The pyrrole monomer concentration in the electrolyte was 0. 0 0 51
Ilol/l (Example 13), 0.02 mol/j! (
Example 14), 1.8 mol/N (Example 1 5), 2
．． 5 mol/& (Example 16), and tetraethylammonium para-toluenesulfonic acid (P T
S (abbreviated) concentration is 0. 'O 0 5 mol/N (Example 17), 0.02 mol/N (Example 18)
, 1.8 mol/1 (Example 19), 2.5 mol/1
(Example 20) An aluminum sintered solid electrolytic capacitor -13- was obtained in accordance with Example 1 except for (Example 20). Table 3 shows the electrical characteristics of the successful capacitor.

Comparative Example 1 Hydrogen peroxide Gao 1/1 and sulfuric acid 0.3Ttlol/
A capacitor was produced according to Example 1 except that the aqueous solution containing 1 was changed to an aqueous solution containing only 6 mol/N of hydrogen peroxide, but the polypyrrole film due to chemical oxidation polymerization did not survive, and as a result, the capacitor was completely destroyed. I couldn't do it.

Comparative Example 2 A capacitor was produced in accordance with Example 1, except that the electrolytic solution was changed to 1 ml of tetraethylammonium para-toluenesulfonic acid. The initial electrical characteristics of the successful capacitor were satisfactory, but the electrical characteristics deteriorated when left at high temperatures.

Example 21 An aluminum sintered element from which an anode lead was taken out was anodized in a chemical solution at +00\I to form a dielectric oxide film.

The element was treated with 2 mol/1 hydrogen peroxide and 0.8 mo sulfuric acid.
It was immersed in an aqueous solution containing 1/# for 20 minutes at room temperature. Next, the device was taken out, held above the liquid level of the pyrrole monomer stock solution, and exposed to pyrrole monomer vapor for 5 minutes to perform chemical oxidative polymerization in the gas phase, and then immersed in the pyrrole monomer stock solution for 15 minutes for chemical oxidation in the liquid phase. Polymerized. After washing and drying, a black polypyrrole film formed by chemical oxidation polymerization was formed on the dielectric oxide film.

Next, the device was reconstituted at 70V in a chemical solution.

After that, the device was immersed in a TTR aqueous solution containing Virolmo 77-0.4 mol/1 and diethylammonium para-toluenesulfonic acid 0.2 mol/& in a stainless steel tank as an electrolyte, and chemical oxidation polymerization was formed on the dielectric oxide film. A platinum wire was brought into contact with a part of the polypyrrole membrane to serve as an anode, and a stainless steel tank was used as a cathode.l). Electrolysis was carried out for 60 minutes at a constant current of 5 mA to form a polypyrrole film by electrolytic polymerization on the polypyrrole film by chemical oxidative polymerization. After taking it out from the electrolyte, it is washed, dried, immersed in colloidal carbon, dried, coated with silver paste, attached a cathode lead, molded with epoxy resin, and the rated voltage is 25.
An aluminum sintered solid electrolytic capacitor with a nominal capacitance of 1.0 μF was obtained. 1 2 of the successful capacitors
The capacitance at 0 Hz was 1.02 μF, the tan δ was 1.12%, and the ESR at 100 KHz was 264′ mΩ.

[Effect of the invention 1] The aluminum sintered electrolytic capacitor using polypyrrole as a solid electrolyte manufactured by the method of the present invention has superior electrical characteristics compared to the aluminum sintered electrolytic capacitor manufactured by the conventionally known method. is obtained. In addition, the method of the present invention has provided an economical manufacturing method with low manufacturing running costs.

Claims (1)

[Claims] 1. After immersing an aluminum sintered element with a dielectric oxide film formed on its surface in an aqueous solution containing hydrogen peroxide and an acid, pyrrole monomer or a water-insoluble solvent containing pyrrole monomer is added. A polypyrrole film is formed by chemical oxidative polymerization on the dielectric oxide film by immersion in a solution, and then the element is immersed in an electrolytic solution containing a pyrrole monomer and para-toluene sulfonate to perform electrolytic polymerization, A method for manufacturing an aluminum sintered solid electrolytic capacitor, comprising forming a polypyrrole film by electrolytic polymerization on a polypyrrole film by chemical oxidative polymerization. 2. The hydrogen peroxide concentration of the aqueous solution containing hydrogen peroxide and acid is 0.05 mol/l to 15.0 mol/l,
2. The method for manufacturing an aluminum sintered solid electrolytic capacitor according to claim 1, wherein the acid concentration is from 0.005 mol/l to 4.0 mol/l. 3. The method for manufacturing a tantalum sintered solid electrolytic capacitor according to claim 1, wherein the acid is sulfuric acid. 4. The method for manufacturing an aluminum sintered solid electrolytic capacitor according to claim 1, wherein the pyrrole monomer concentration of the water-insoluble solvent solution containing the pyrrole monomer is 10 vol% or more. 5 The concentration of pyrrole monomer in the electrolytic solution containing pyrrole monomer and para-toluene sulfonate is 0.005.
mol/l to 3.0 mol/l, and the paratoluenesulfonate concentration is 0.005 mol/l to 3.0 mol.
2. The method for manufacturing an aluminum sintered solid electrolytic capacitor according to claim 1, wherein the aluminum sintered solid electrolytic capacitor is 1/l.