JP2785565B2 - Manufacturing method of capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a capacitor using a conductive polymer film for at least one of electrodes facing each other via a dielectric film.

[0002]

2. Description of the Related Art Recently, with the digitization of electrical equipment, the capacitors used therein have low impedance in the high frequency range, and there is an increasing demand for smaller and larger capacitors. Conventionally, plastic film capacitors, mica capacitors, multilayer ceramic capacitors, and the like have been used as high-frequency capacitors. Other examples include an aluminum dry electrolytic capacitor and an aluminum or tantalum solid electrolytic capacitor.

In an aluminum dry electrolytic capacitor, an etched positive and negative electrode aluminum foil is wound through a paper separator, and a liquid electrolyte is used. Further, in an aluminum or tantalum solid electrolytic capacitor, the electrolyte is solidified to improve the characteristics of the aluminum electrolytic capacitor. To form the solid electrolyte, the anode foil is immersed in a manganese nitrate solution and thermally decomposed in a high-temperature furnace at about 350 ° C. to form a manganese dioxide layer. In the case of this capacitor, since the electrolyte is solid, there are no drawbacks such as volatilization of the electrolyte at a high temperature and functional deterioration caused by solidification in a low temperature range, and the capacitor exhibits better frequency characteristics and temperature characteristics than a liquid electrolyte. Also, the aluminum electrolytic capacitor can realize a large capacity because the oxide film serving as a dielectric can be made very thin like the tantalum electrolytic capacitor.

In recent years, a solid electrolytic capacitor using an organic semiconductor such as 7,7,8,8-tetracyanoquinodimethane (TCNQ) salt as a solid electrolyte (Japanese Patent Laid-Open No.
17609) has been developed.

Further, a polymerizable monomer such as pyrrole, thiophene or furan is electrolytically polymerized into a conductive polymer,
There is also a method of using this for at least one of the electrodes of a capacitor.A polyimide thin film serving as a dielectric is formed on the electrode surface by an electrodeposition method, a chemically polymerized conductive polymer film is laminated, and an electrolytic polymerized conductive polymer film is further formed. Are disclosed (Electrochemical Society of Japan, Spring 1991, No. 5).
8th Annual Meeting Abstracts, P251 and P252)

[0006]

As described above, various types of capacitors are used. However, film capacitors and mica capacitors have large shapes because of their large shapes. However, it has disadvantages such as extremely high price and poor temperature characteristics.

[0007] Further, since the aluminum electrolytic capacitor is easily damaged by the oxide film, it is necessary to repair the damage as needed by applying an electrolyte between the oxide film and the cathode. For this reason, those that use a liquid electrolyte as the electrolyte may cause a decrease in capacitance or an increase in loss over time due to electrolyte leakage or ionic conductivity, etc. It has disadvantages such as a large loss.

Next, the solid electrolyte will be described.
The loss in the high frequency range is not sufficiently small due to the damage of the oxide film due to thermal decomposition several times at a high temperature and the high specific resistance of manganese dioxide. Also, TCNQ
Solid electrolytic capacitors using organic semiconductors such as salt show superior high-frequency characteristics compared to those using manganese dioxide.However, the increase in specific resistance when applying organic semiconductors and the adhesion to anode foil It cannot be said that it exhibits ideal characteristics due to its weakness.

Further, when a conductive polymer thin film is used as an electrode of a capacitor, frequency characteristics, temperature characteristics, high temperature life characteristics and the like are excellent. However, since the dielectric film is easily attacked by moisture, it has a drawback in high-temperature and high-humidity life characteristics.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a manufacturing method for efficiently manufacturing a highly reliable capacitor having excellent high-temperature and high-humidity life characteristics.

[0011]

Means for Solving the Problems The present invention attains the above object, and a method of manufacturing a capacitor according to the present invention comprises forming at least an electrode having a dielectric film formed on at least one electrode selected from silicic acid or silicate. After immersion in an electrode treatment aqueous solution comprising at least one selected from phosphoric acid or phosphate, a conductive polymer is formed by electrolytic polymerization using an electrolytic solution containing at least a polymerizable monomer and a supporting electrolyte. It is used as an electrode.

The silicic acid or silicate of the present invention may be used alone or in combination of two or more. Although the concentration of silicic acid or silicate in the electrolytic solution is effective even in a very small amount, it is preferably 1 × 10 ⁻⁴ mol / l or more, and more preferably 1 × 10 ⁻³ mol / l.
The effect is particularly large at mol / l or more.

The phosphoric acid or phosphate of the present invention may be used alone or in combination of two or more. Although the concentration of phosphoric acid or phosphate in the electrolytic solution is effective even in a very small amount, it is preferably 1 × 10 ⁻⁵ mol / l or more,
At least 10 ^-4 mol / l is particularly effective.

The time during which the electrode on which the dielectric film is formed is immersed in an electrode treatment aqueous solution comprising at least one selected from silicic acid or silicate and at least one selected from phosphoric acid or phosphate of the present invention. Is effective for 1 hour, but is preferably 12 hours or more, and is especially effective for 24 hours or more.

The polymerizable monomers of the present invention include:
As in the invention according to claim 5, pyrrole, thiophene or a derivative thereof (for example, N-methylpyrrol)
Or at least one of the following, but for example, may be furan or the like. The supporting electrolyte may be any generally used one such as perchlorate, sulfonate, carboxylate, phosphate and the like.
Naphthalene sulfonates or alkyl phosphates having an alkyl substituent as in the invention of the above are preferred. More specifically, there may be mentioned sodium monomethylnaphthalenesulfonate, sodium triisopropylnaphthalenesulfonate, sodium monoisopropylnaphthalenesulfonate, sodium dibutylnaphthalenesulfonate, propyl phosphate, butyl phosphate, hexyl phosphate, and the like.

Also, the above-mentioned monomers and supporting electrolytes are not used alone, but a plurality of kinds of supporting electrolytes are used in combination, such as a mixture of plural kinds of supporting electrolytes, or a mixture of pyrrole and thiophene with their derivatives. You may use together. Further, an appropriate additive may be added to the electrolytic solution in order to composite the conductive polymer layer. Note that the present invention is not limited to the compounds and treatment steps exemplified above. It goes without saying that alternative compounds and processing steps other than those exemplified may be used.

[0017]

According to the present invention, as described above, at least one electrode selected from silicic acid or silicate is added to at least one electrode selected from silicic acid or silicate before forming an electropolymerized conductive polymer film. Since the immersion treatment is performed with an aqueous solution of an electrode treatment consisting of at least one selected from the group consisting of acid salts, the hydrated dielectric film is suppressed and the resulting polymerized conductive polymer has excellent thermal stability. Since the film is laminated and used as a counter electrode, a capacitor with little deterioration in characteristics even when left under high temperature and high humidity can be obtained.

[0018]

(Embodiment 1) As a first embodiment, application of the present invention to an aluminum electrolytic capacitor will be described with reference to the drawings.

A heat-resistant insulating tape 8 was applied to the surface of the valve action metal 2, and the smaller one was used as the anode lead mounting surface, and the larger one (4 mm × 5 mm) was used as the dielectric film forming surface. 7% of valve action metal foil 2 (aluminum etched foil)
Using an aqueous solution of ammonium adipate, about 70 ° C, 40
Anodic oxidation under the condition of an applied voltage of 42 V for 3 minutes.
And then apply manganese nitrate aqueous solution
Thermal decomposition at 20 ° C. for 20 minutes to form a conductive layer composed of a manganese oxide film 4, and as shown in FIG. 1, the surface on which the dielectric film 3 and the manganese oxide film 4 were formed was treated with sodium silicate (0.01 mol). / L) and phosphoric acid (0.001 mol /
The electrode was immersed in the electrode treatment aqueous solution 9 at 25 ° C. for 24 hours.

Next, as shown in FIG. 2, pyrrole (0.25
mol / l), triisopropylnaphthalenesulfonate (0.1 mol / l), water
0, the polymerization start electrode 7 is brought close to the manganese oxide film 4, and a constant voltage of 2.5 V is applied between the electrode 13 and the cathode 13 for 30 minutes. Is formed, a carbon paint layer 11 and a silver paint layer 12 are laminated as shown in FIG. 3, and an anode lead 1 and a cathode lead 6 are provided as shown in FIG. A capacitor was obtained. The number of samples is 10.

The initial capacity and loss factor of the obtained capacitor at 120 Hz were measured. After that, 5 under high temperature and high humidity
After exposure for 00 hours, the capacity and the loss factor at 120 Hz were measured again. The average of the measured values is shown in (Table 1).

As Comparative Example 1, ten capacitors were manufactured under the same conditions as above except that the electrode treatment was not performed, and the same measurement was performed. The average of the measured values is shown in (Table 1).
As is clear from these (Table 1), in the capacitor according to the present example, the difference between the characteristics after the accelerated life test and the initial characteristics is significantly smaller than that in Comparative Example 1, and an excellent effect is obtained.

As described above, according to the present embodiment, the hydration of the dielectric film is suppressed, and the electropolymerized conductive polymer film used for the electrode has excellent thermal stability. High performance capacitors can be realized.

[0024]

[Table 1]

(Example 2) A capacitor was produced in the same manner as in (Example 1) except that the electrode on which the dielectric film was formed was immersed in an electrode treatment solution for 1 hour. The number of samples is 10. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1).

As is apparent from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is remarkably small as compared with Comparative Example 1, and excellent effects are obtained as in Example 1. Can be

(Example 3) The concentration of phosphoric acid was set to 0.01 mol.
A capacitor was produced in the same manner as in (Example 1) except that 1 / l was set. The number of samples is 10. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1).

As is clear from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is remarkably small as compared with Comparative Example 1, and excellent effects are obtained as in Example 1. Can be

Example 4 A capacitor was manufactured in the same manner as in Example 1 except that ammonium dihydrogen phosphate was used instead of phosphoric acid. The number of samples is 10. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1).

As is apparent from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is remarkably small as compared with Comparative Example 1, and excellent effects are obtained as in the first embodiment. Can be

Example 5 A capacitor was manufactured in the same manner as in (Example 1) except that sodium dihydrogen phosphate was used instead of phosphoric acid. The number of samples is 10. The obtained capacitor was measured in the same manner as in (Example 1).
The characteristics are shown in (Table 1).

As is clear from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is remarkably small compared to Comparative Example 1, and excellent effects can be obtained as in Example 1. Can be

Example 6 A capacitor was manufactured in the same manner as in Example 1 except that diammonium hydrogen phosphate was used instead of phosphoric acid. The number of samples is 10. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1).

As is clear from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is significantly smaller than that of Comparative Example 1, and excellent effects are obtained as in the first embodiment. Can be

(Example 7) A capacitor was manufactured in the same manner as in (Example 1) except that potassium silicate (0.01 mol / l) was used instead of sodium silicate. The number of samples is 10. The obtained capacitor was (Example 1)
The same measurement was performed. As is clear from Table 1 which shows the characteristics, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present example is significantly smaller than that of Comparative Example 1. As in Example 1, excellent effects can be obtained.

Example 8 A capacitor was manufactured in the same manner as in Example 1 except that silicic acid (0.01 mol / l) was used instead of sodium silicate. 10 samples
Individual. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1).

As is clear from Table 1 above, the capacitor according to the present embodiment has a remarkably small difference between the characteristics after the accelerated life test and the initial characteristics as compared with Comparative Example 1, and excellent effects are obtained as in Example 1. Can be

Example 9 Instead of pyrrole and water,
A capacitor was manufactured in the same manner as in (Example 1) except that thiophene and acetonitrile were used. 1 sample
There are zero. The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1). As Comparative Example 2, 10 capacitors were manufactured under the same conditions as above except that the electrode treatment was not performed, and the same measurement was performed.
The average of the measured values is shown in (Table 1).

As is apparent from Table 1 above, the capacitor according to the present embodiment has a remarkably small difference between the characteristics after the accelerated life test and the initial characteristics, as compared with Comparative Example 2, and provides excellent effects as in Example 1. Can be

Example 10 A capacitor was produced in the same manner as in Example 1 except that sodium dibutylnaphthalenesulfonate was added to the electrolytic polymerization solution instead of sodium triisopropylnaphthalenesulfonate. The number of samples is 10. The obtained capacitor was (Example 1)
The same measurement was performed. The characteristics are shown in (Table 1). As Comparative Example 3, 10 capacitors were manufactured under the same conditions as above except that the electrode treatment was not performed, and the same measurement was performed. The average of the measured values is shown in (Table 1).

As is apparent from Table 1, the difference between the characteristics after the accelerated life test and the initial characteristics of the capacitor according to the present embodiment is remarkably small as compared with Comparative Example 3, and excellent effects are obtained as in the first embodiment. Can be

Example 11 A capacitor was produced in the same manner as in Example 1 except that n-butyl phosphate was added to the electrolytic polymerization solution instead of sodium triisopropylnaphthalenesulfonate. The number of samples is 10.
The obtained capacitor was measured in the same manner as in (Example 1). The characteristics are shown in (Table 1). As Comparative Example 4, ten capacitors were manufactured under the same conditions as above except that the electrode treatment was not performed, and the same measurement was performed. The average of the measured values is shown in (Table 1).

As is apparent from Table 1 above, the capacitor according to the present embodiment has a remarkably small difference between the characteristics after the accelerated life test and the initial characteristics as compared with Comparative Example 3 and achieves excellent effects as in Example 1. Can be

In the examples, only the case where sodium silicate or potassium silicate is used as the silicate has been described, but other silicates can be used as long as they dissociate into cations and anions in water even in a small amount. It is.

In the examples, only the case where ammonium dihydrogen phosphate, sodium dihydrogen phosphate or diammonium hydrogen phosphate was used as the phosphate was described. Other phosphates can be used as long as they do.

In the examples, only the case where thiophene was used in addition to pyrrole as the polymerizable monomer was described, but other polymerizable monomers can also be used.

In the examples, only the case where triisopropylnaphthalenesulfonate, dibutylnaphthalenesulfonate, and nbutylphosphate were used as the supporting electrolyte was described. However, the electrolytic polymerization solution has a necessary electric conductivity. If the ions are included in the conductive polymer as a dopant, the effect of the present invention is not limited by the types of cations and anions of the supporting electrolyte.

In the embodiment, only the case where manganese oxide was formed using manganese nitrate was described. However, the present invention is not limited to manganese nitrate, and other materials that can form manganese oxide can be used. .

In the embodiment, only a solid electrolytic capacitor using aluminum as a valve metal as an anode has been described. However, as is clear from the gist of the present invention, other materials having electric conductivity usable as an electrode can be used. Can also be used.

In the embodiment, only the case where aluminum oxide is used as the dielectric has been described. However, the present invention can be applied to the case where other materials which can be used as the dielectric of the capacitor, such as electrodeposited polyimide, used in the prior art, are used. The effect of the invention is not hindered.

In the embodiment, only the capacitor having polarity has been described. However, as is clear from the gist of the present invention, the same effect can be obtained with a non-polar capacitor.

In the embodiment, only the case where a conductive polymer is used for one electrode has been described. However, it is also possible to use a conductive polymer for another electrode. It is not limited by the number of electrodes using.

[0053]

As described above, according to the present invention, an electrode on which a dielectric film is formed is treated with an electrode comprising at least one selected from silicic acid or silicate and at least one selected from phosphoric acid or phosphate. After being immersed in an aqueous solution, an electrolytic polymerized conductive polymer is formed using an electrolytic solution containing at least a polymerizable monomer and a supporting electrolyte and used as an electrode. It can be manufactured well.

[Brief description of the drawings]

FIG. 1 is a diagram in which an electrode on which a dielectric film is formed according to one embodiment of the present invention is immersed in an electrode treatment aqueous solution.

FIG. 2 is a view showing formation of an electropolymerized conductive polymer film in the embodiment.

FIG. 3 is a cross-sectional view of the capacitor manufactured in the same example.

FIG. 4 is a plan view of the capacitor manufactured in the same example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode lead 2 Valve metal 3 Dielectric film 4 Manganese oxide film 5 Electropolymerized conductive polymer film 6 Cathode lead 7 Polymerization initiation electrode 8 Heat resistant insulating tape 9 Electrode treatment aqueous solution 10 Polymerization solution 11 Carbon paint film 12 Silver paint Membrane 13 cathode

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Koichi Yoshida 3-1-1, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa Matsushita Giken Co., Ltd. (56) References JP-A-5-90080 (JP, A) Kaihei 4-307914 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01G 9/028

Claims (5)

(57) [Claims] Claims 1. An electrode on which at least a dielectric film is formed is immersed in an electrode treatment aqueous solution comprising at least one selected from silicic acid or silicate and at least one selected from phosphoric acid or phosphate, A method for producing a capacitor, comprising forming a conductive polymer by electrolytic polymerization using an electrolytic solution containing at least a polymerizable monomer and a supporting electrolyte. 2. The method according to claim 1, wherein the silicic acid or silicate is at least one selected from ethyl silicate, potassium silicate, calcium silicate, tetraethyl silicate, tetraphenyl silicate, tetramethyl silicate and sodium silicate. Manufacturing method of capacitor. 3. The phosphoric acid or phosphate is selected from diammonium hydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate. The method for manufacturing a capacitor according to claim 1, wherein at least one is provided. 4. The method according to claim 1, wherein the supporting electrolyte is selected from a naphthalene sulfonate or an alkyl phosphate having an alkyl substituent. 5. The method according to claim 1, wherein the polymerizable monomer is selected from at least one of pyrrole, thiophene, and derivatives thereof.