JPH0521284A - Capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To realize a small size and large capacity capacitor which employs a conductive polymer layer as an electrode, has excellent frequency characteristics and has excellent reliability characteristics, that is, even if it is left in a high temperature atmosphere, it shows only little deterioration of capacity, loss, impedance, etc. CONSTITUTION:A layer of conductive polymer which is obtained by an electrolytic polymerization method from electrolyte which contains at least phenol and/or phenoxide derivative, polymerizing monomer and supporting electreolyte is built up on a dielectric film and used as an electrode. With this constitution, various characteristics of the conductive polymer layer under a high temperature can be stabilized and a capacitor having excellent stability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor using a conductive polymer layer as an electrode and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the digitization and miniaturization of circuits in electrical equipment and the like, it has been strongly demanded that capacitors used in circuits have a low impedance in a high frequency range, a small size and a large capacity. It's coming. Under such circumstances, development of a large-capacity solid electrolytic capacitor using a conductive solid as an electrolyte has been actively conducted.

Conventionally, a tantalum solid electrolytic capacitor using manganese dioxide as a solid electrolyte has been well known, but it has been impossible to obtain a sufficiently low impedance in a high frequency region because of the high resistance of manganese dioxide. In addition, as a solid electrolytic capacitor, instead of the manganese dioxide layer, an organic semiconductor having high conductivity and excellent anodizing property, 7,7,8,8-tetracyanoquinodimethane complex salt (TCNQ salt) is used as a solid. Although the one used as an electrolyte has been proposed, there have been problems that the resistivity increases when the TCNQ salt is applied and the adhesion to the anode metal foil is poor.

Therefore, by conducting electropolymerization using a solution containing a heterocyclic compound monomer such as pyrrole or thiophene and a supporting electrolyte, a conductive polymer layer containing an anion of the supporting electrolyte as a dopant is used as a solid electrolyte. Things have been proposed. Electropolymerization Conductive polymer is TCN
Even if compared with Q salt, the electric conductivity is very large, and a film having excellent adhesiveness can be easily produced. Furthermore, when a conductive polymer is used, it is easy to make a capacitor into a chip. For this reason, a small-sized, large-capacity capacitor having ideal impedance frequency characteristics can be realized, and therefore a solid electrolytic capacitor using a conductive polymer is drawing attention.

More recently, a nonpolar capacitor has been proposed in which a polyimide thin film produced by electrodeposition is used as a dielectric, and a conductive polymer is laminated on this to form an electrode (The 58th Congress of the Electrochemical Society of Japan). It is proposed to use not only conductive polymer as an electrolyte of solid electrolytic capacitors but also electrodes of all capacitors p252).

[0006]

However, in general, when a conductive polymer is left at a high temperature for a long time, various properties such as electric conductivity, mechanical strength and adhesiveness are deteriorated. The produced capacitor also has a problem that these characteristics deteriorate if it is left at high temperature for a long time.

In view of the above problems, the present invention provides a capacitor excellent in life characteristics even at high temperature, and a method for manufacturing the same, even though it has a conductive polymer layer produced by electrolytic polymerization as an electrode of the capacitor. The purpose is to do.

[0008]

In order to achieve the above object, the present invention provides a capacitor having an electrode in which a conductive polymer is laminated on a dielectric film, wherein the conductive polymer is phenol or It is composed of at least one selected from phenoxide, a polymerizable monomer, and a supporting electrolyte, and in the method for producing a capacitor of the present invention, a conductive polymer layer is formed from an electrolytic solution having the above structure by electrolytic polymerization. Is configured to obtain.

The phenol used in the present invention is an aromatic hydroxy compound, and is not limited by the number and position of hydroxyl groups, and in addition to monohydric phenols, polyhydric phenols, bisphenols, naphthols, binaphthols, It also contains anthrol and anthrahydroquinone. Phenoxide is a salt of the above-mentioned phenol, and includes ammonium salts as well as metal salts such as sodium, potassium, calcium, barium and aluminum.

More specifically, carboxylic acid (phenol), catechol, resorcin, hydroquinone, pyrogallol, phloroglucin, bisphenol A, α-naphthol, β-naphthol, α-binaphthol, β-binaphthol, γ-binaphthol, α-ant. Roll, β-
Anthrol, γ-anthrol, anthrahydroquinone, sodium phenoxide, potassium phenoxide,
Calcium phenoxide etc. are mentioned. The above-mentioned phenol or phenoxide derivative may be used alone or as a mixture of both.

Further, the higher the concentration of the above-mentioned phenol or phenoxide added to the electrolytic solution, the better the effect.
It is preferably 005 mol / liter or more, and more preferably 0.1 mol / liter or more.

The capacitor of the present invention uses the above conductive polymer for at least one of the two electrodes. However, in order to increase the capacity of the capacitor, the effective surface area of one electrode is It is more preferable to increase the size. For this method, it is preferable to use an etched metal or a sintered body, and further, an etched foil or a sintered body of aluminum, tantalum or the like is most suitable.

Further, at least one hydrogen atom of the phenol or phenoxide used in the present invention can be replaced by halogen. Specific examples include fluorophenol, chlorophenol, bromophenol, iodophenol and the like.

As the polymerizable monomer used in the present invention, at least one of pyrrole and its derivative (for example, N-methylpyrrole) can be mentioned, but other than that, for example, thiophene, furan and the like may be used.

The supporting electrolyte may be any of those commonly used, such as perchlorates, sulfonates, carboxylates and phosphates, but naphthalenesulfonic acid having an alkyl substituent. Salts or alkyl phosphates are preferred. More specifically, sodium monomethylnaphthalene sulfonate, sodium triisopropyl naphthalene sulfonate, sodium monoisopropyl naphthalene sulfonate, sodium dibutyl naphthalene sulfonate, propyl phosphate,
Examples thereof include butyl phosphate ester and hexyl phosphate ester.

The above-mentioned polymerizable monomers and supporting electrolytes may be used alone, for example, a plurality of supporting electrolytes may be mixed, or pyrrole or thiophene may be mixed with each derivative. A plurality of types of the above-mentioned monomers may be used in combination.

Further, other desired additives may be added to the electrolytic solution in order to form a composite with the conductive polymer. Also,
It is needless to say that the present invention is not limited to the above-exemplified compounds and treatment steps, and that substitutable compounds and treatment steps other than the exemplified ones may be used.

[0018]

With the above structure, the capacitor of the present invention has a conductive polymer layer having a well-structured structure, and there are few starting points for deterioration such as oxidation starting points. The deterioration of various properties that occurs when the conductive polymer is left under high temperature for a long time is dominated by the deterioration caused by the oxidation of oxygen in the air and the conductive polymer, so that the present invention has a small starting point of deterioration. Even if the conductive polymer layer of the capacitor is left at high temperature for a long time, the electrical conductivity, mechanical strength, adhesiveness, and other characteristics are not significantly deteriorated. As a result, the capacitor of the present invention can be a capacitor having excellent stability of various characteristics even at high temperatures, even though the conductive polymer is used for the electrodes.

[0019]

EXAMPLES Examples of the present invention will be described in detail below.

(Embodiment 1) FIG. 1 shows a sectional view of a capacitor of the present invention.

First, 7 mm in length and 10 in width with an anode lead attached.
A 3% ammonium adipate aqueous solution was used for the aluminum etched foil 1 having a thickness of 30 mm, and anodic oxidation was performed for 40 minutes under conditions of about 70 ° C. and an applied voltage of 70 V to form the dielectric film 2 on the surface of the etched foil. Then, manganese nitrate 30
% Aqueous solution and let it air dry, then 30 at 300 ℃
A heating treatment was performed by heating for a minute to form a conductive layer composed of the manganese oxide layer 3 on the dielectric film. Next, the etched foil provided with such a conductive layer is treated with phenol (0.1
5M), pyrrole (0.5M), sodium triisopropylnaphthalenesulfonate (0.1M) and water, and placed in an electropolymerization solution to bring the polymerization initiating electrode close to the conductive layer. A constant voltage of 0.5 V was applied for 50 minutes to carry out an electrolytic polymerization reaction to form an electrolytic polymerization polypyrrole layer 4. This is washed with water and dried, and then a carbon layer 5 and a silver paint layer 6 are sequentially provided on the electropolymerized layer 4,
A capacitor of the present invention was obtained. The number of manufactured pieces is 10.

After aging the obtained capacitor for 1 hour at 20V, the initial capacity and loss coefficient (120H
z) was measured. After that, 100 at high temperature (125 ℃)
After exposure for 0 hours, capacity and loss factor (120H
z) was measured. The average value of the measured values is shown in (Table 1) and evaluated.

(Comparative Example 1) For comparison, 10 capacitors for comparison were prepared under the same conditions as above except that phenol was not added to the electrolytic polymerization solution, and the same measurement was performed and evaluated. The average value of the measured values is shown in Table 1 as Comparative Example 1.
Comparing the two, it can be clearly seen that the capacitor of the present invention has far superior stability at high temperatures.

Example 2 Ten capacitors of the present invention were produced in the same manner as in Example 1 except that hydroquinone was added to the electrolytic polymerization liquid instead of phenol. After aging the obtained capacitor at 20 V for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. afterwards,
After exposing at high temperature (125 ° C) for 1000 hours,
The capacity and loss factor (120 Hz) were measured. The average value of the measured values is shown in (Table 1).

As compared with Comparative Example 1, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

Example 3 Example 1 was repeated except that sodium phenoxide was added to the electrolytic polymerization solution in place of phenol.
Ten capacitors of the present invention were produced in the same manner as in.
After aging the obtained capacitor at 20 V for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. After that, after being exposed to a high temperature (125 ° C.) for 1000 hours, the capacity and the loss coefficient (120 Hz) were measured again. The average value of the measured values is shown in (Table 1).

As compared with Comparative Example 1, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

Example 4 Ten capacitors of the present invention were produced in the same manner as in Example 1 except that p-fluorophenol was added to the electrolytic polymerization liquid instead of phenol. After aging the obtained capacitor at 20 V for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. After that, after being exposed to a high temperature (125 ° C.) for 1000 hours, the capacity and the loss coefficient (120 Hz) were measured again. The average value of the measured values is shown in (Table 1).

As compared with Comparative Example 1, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

Example 5 Ten capacitors of the present invention were produced in the same manner as in Example 1 except that α-naphthol was added to the electrolytic polymerization liquid instead of phenol. After aging the obtained capacitor at 20 V for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. afterwards,
After exposing at high temperature (125 ° C) for 1000 hours,
The capacity and loss factor (120 Hz) were measured. The average value of the measured values is shown in (Table 1).

As compared with Comparative Example 1, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

Example 6 Ten capacitors of the present invention were produced in the same manner as in Example 1 except that n-butyl phosphate was used instead of sodium triisopropylnaphthalene sulfonate. The obtained capacitor is 20V
After aging for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. Then, under high temperature (125
After exposure to (° C.) for 1000 hours, the capacity and loss coefficient (120 Hz) were measured again. The average value of the measured values is shown in (Table 1).

Comparative Example 2 For comparison, 10 capacitors for comparison were prepared under the same conditions as in Example 6 except that phenol was not added to the electrolytic polymerization solution, and the same measurement was performed. The average value of the measured values is shown in Table 1 as Comparative Example 2.
Comparing the two, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

(Example 7) Pyrrole (0.5M), sodium triisopropylnaphthalenesulfonate (0.1M)
M) and water instead of the electrolyte solution, thiophene (0.
5 capacitors), 10 capacitors of the present invention were prepared in the same manner as in Example 1 except that an electrolytic solution containing tetrabutylammonium paratoluenesulfonate (0.1M) and acetonitrile was used. After aging the obtained capacitor at 20 V for 1 hour, the initial capacity and loss coefficient (120 Hz) were measured. Then, under high temperature (125
After exposure to (° C.) for 1000 hours, the capacity and loss coefficient (120 Hz) were measured again. The average value of the measured values is shown in (Table 1).

Comparative Example 3 For comparison, 10 capacitors were prepared under the same conditions as in Example 7 except that phenol was not added to the electrolytic polymerization solution, and the same measurement was performed. The average value of the measured values is shown in Table 1 as Comparative Example 3. Comparing the two, it can be clearly seen that the capacitor according to the present invention has far superior stability at high temperatures.

In the above embodiments, only the solid electrolytic capacitor using the valve metal is shown. However, since the present invention is an improvement of the conductive polymer used for the electrode, the conductive polymer is used for the electrode. Obviously, any capacitor can be used.

[0037]

[Table 1]

[0038]

As described above, in the capacitor of the present invention and the method for producing the same, the electrolytic polymerization method is carried out from the electrolytic solution containing at least one selected from phenol or phenoxide, the polymerizable monomer and the supporting electrolyte. A capacitor having excellent stability even at high temperatures, even though the conductive polymer layer is used as an electrode, by using the conductive polymer obtained by Can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a capacitor according to an embodiment of the present invention.

[Explanation of symbols]

1 Aluminum Etched Foil 2 Dielectric film 3 Manganese oxide layer 4 Electropolymerized polypyrrole layer 5 carbon layer 6 silver paint layer

Continued front page    (72) Inventor Shigenari Nanai             3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture             No. Matsushita Giken Co., Ltd.

Claims (5)

[Claims] 1. An electrode comprising an electrically conductive polymer laminated on a dielectric film, wherein the electrically conductive polymer layer comprises at least one selected from phenol or phenoxide, a polymerizable monomer and a supporting electrolyte. A capacitor that is characterized by. 2. The capacitor according to claim 1, wherein at least one of hydrogens contained in phenol or phenoxide is replaced with halogen. 3. The capacitor according to claim 1, wherein the polymerizable monomer is pyrrole or a derivative thereof. 4. The capacitor according to claim 1, wherein the supporting electrolyte is a naphthalene sulfonate having an alkyl substituent or an alkyl phosphate. 5. The method for producing a capacitor according to claim 1, wherein the conductive polymer layer is formed by an electrolytic polymerization method.