JPH0521295A - Manufacture of laminated solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a small size and large capacity laminated solid electrolytic capacitor having excellent frequency characteristics by a method wherein electrolytically polymerized conductive polymer films are built up on manganese oxide layers formed on at least two valve metal foils to cover and fix the valve metal foils and then polymerization starting parts are cut off and removed. CONSTITUTION:Dielectric films 2 and manganese oxide films 3 are successively formed on at least two valve metal foils. The respective parts of the valve metal foils are exposed by removing the dielectric films on those parts and the valve metal foils are electrically connected to each other and laminated and fixed together. Then conductive parts which are so provided as to be brought into contact with the parts of the valve metal foils exposed by the removal of the dielectric films 2 are used as polymerization starting parts to perform electrolytic polymerization. Then electrolytically polymerized conductive polymer films 7 are built up on the manganese oxide films 3. The two or more valve metal foils are covered and fixed. After that, the polymerization starting parts are cut off and removed. With this constitution, the laminated structure is already obtained when polymerization reaction is finished, so that a laminated solid electrolytic capacitor can be manufactured easily.

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 laminated solid electrolytic capacitor using a conductive polymer as a solid electrolyte.

[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 low impedance in a high frequency region and be small in size and large in capacity. It's coming. Under such circumstances, a large-capacity solid electrolytic capacitor using a conductive solid as an electrolyte has been actively developed.

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 the solid electrolytic capacitor, an organic semiconductor having high conductivity and excellent anodizing property, 7,7,8,8, -tetracyanoquinodimethane complex salt (TCNQ salt), is used instead of the manganese dioxide layer. Although the one used for a solid electrolyte has been proposed, there have been problems that the specific resistance increases when the TCNQ salt is applied and the adhesiveness with the anode metal foil is weak.

Therefore, recently, 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 solid electrolyte. Have been proposed for use. The electropolymerized conductive polymer has very high electric conductivity as compared with TCNQ salt, and a film having excellent adhesiveness can be easily prepared. For this reason,
A solid electrolytic capacitor using a conductive polymer, which can realize an ideal frequency characteristic of impedance, is particularly attracting attention.

[0005]

However, since the anode valve metal is covered with the dielectric film which is an insulator,
In this state, it is extremely difficult to uniformly form the electropolymerized conductive polymer on the valve metal by electrolytic polymerization. Further, in order to increase the capacity of the capacitor, it is necessary to stack anode foils, but in order to stack the elements one by one after electrolytic polymerization, there is a problem that the device becomes large and the yield decreases. .

In view of the above circumstances, the present invention makes it possible to uniformly form an electrolytically polymerized polymer layer, which is a solid electrolyte, on a valve metal having a dielectric film so that a laminated solid electrolytic capacitor can be easily manufactured. The purpose is to

[0007]

To achieve the above object, the present invention removes a part of a dielectric film on at least two valve metal foils on which a dielectric film and a manganese oxide are sequentially formed. Electrical conductivity between the valve metals is fixed, laminated and fixed, and electropolymerization is performed using the conductive part provided in contact with the valve metal from which the dielectric film has been removed as the polymerization initiation part, and electropolymerized conductive on manganese oxide. At least 2 by laminating functional polymer films
It is configured to cover and fix a sheet of valve metal foil, and thereafter cut and remove the polymerization initiation portion.

[0008]

According to the present invention, by virtue of the above structure, the electrolytic polymer can be uniformly grown from the conductive portion provided in contact with the valve metal only by applying a voltage to the anode valve metal, and the grown conductive high The molecule can cover and fix two or more valve metals. Therefore, when the polymerization reaction is completed, it is already a laminated type, and a laminated solid electrolytic capacitor can be easily manufactured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, a first embodiment of a method for manufacturing a laminated solid electrolytic capacitor according to the present invention will be described.

FIG. 1 shows a sheet of aluminum etched foil 1 to be laminated. FIG. 1A is a plan view and FIG.
1B is a sectional view taken along the line AA ′ in FIG.
This aluminum etched foil 1 was subjected to anodic oxidation for 40 minutes at a temperature of about 70 ° C. and an applied voltage of 70 V using a 3% aqueous solution of ammonium adipate to form a dielectric film 2 on the surface of the etched foil. Then, manganese nitrate 3
Immerse in 0% aqueous solution and let it air dry, then 300 at 300 ℃
A heating treatment was carried out by heating for a minute to form a manganese oxide layer 3 on the dielectric film 2.

Next, as shown in FIG. 2 ((a) is a perspective view and (b) is a cross-sectional view taken along the line AA 'of (a)), a nickel foil piece 4 as a polymerization initiation portion is welded to the protrusion. The two etched foils 1 provided on the aluminum etched foil 1 and provided with the manganese oxide layer 3 are fixed. As the conductive portion provided in contact with the valve metal that is the starting portion of electrolytic polymerization, a metal that is not anodized is most suitable, but silver paste, carbon pesto, or the like may be used, and further, chemically polymerized conductive polymer or the like may be used. . At least one polymerization initiation portion may be provided, and a plurality of polymerization initiation portions may be provided in order to shorten the polymerization time, and it is more preferable to provide it between the valve metals to be laminated.

Then, pyrrole (0.5M) and sodium triisopropylnaphthalenesulfonate (0.1M)
A constant voltage of 2.5 V is applied for 30 minutes to the two-layered etched foils 1 arranged in an electrolytic polymerization solution consisting of water and water to perform an electrolytic polymerization reaction, and an electrolytic polymerization polypyrrole 7 for solid electrolyte is formed as shown in FIG. Formed. Examples of the electropolymerized conductive polymer film laminated on the manganese oxide layer 3 include at least one of pyrrole and a derivative thereof (for example, N-methylpyrrole), but other examples include “thiophene”. It may be "franc" or the like.

The supporting electrolyte used in the electropolymerization may be any one commonly used other than perchlorates, sulfonates, carboxylates, phosphates and the like. A naphthalene sulfonate or an alkyl phosphate having a substituent is preferable. More specifically, sodium monomethylnaphthalenesulfonate, sodium triisopropylnaphthalenesulfonate, sodium monoisopropylnaphthalenesulfonate, sodium dibutylnaphthalenesulfonate,
Examples thereof include propyl phosphate ester, butyl phosphate ester, hexyl phosphate ester and the like.

It is to be noted that a plurality of types of the above-mentioned monomers may be used in combination such that the above-mentioned monomers and supporting electrolytes are not used alone, but a plurality of types of supporting electrolytes are mixed, or pyrrole and thiophene are mixed with their respective derivatives. May be. Further, in order to form a composite with the solid electrolyte, an appropriate additive may be added to the electrolytic solution.

After the solid electrolyte is formed, it is washed with water and dried, and then the carbon layer 5 and the silver paste layer 6 are sequentially provided on the electrolytically polymerized polypyrrole 7, and then the nickel foil piece 4 at the polymerization initiation portion is formed.
The protruding portion provided with was bent and removed. Then, it was packaged with an epoxy resin to obtain a laminated solid electrolytic capacitor. The number of manufactured pieces is 10. The obtained solid electrolytic capacitor is 2
After aging at 0 V for 1 hour, the capacity, loss factor and leakage current at 120 Hz were measured. In addition, 500
The impedance at kHz was measured and the average value is shown in (Table 1). The measured capacitance value was the capacitance of about two aluminum etched foils.

[0017]

[Table 1]

(Comparative Example 1) For comparison, 10 capacitors were used under the same conditions as above except that the polymerization was started from the part where the dielectric film was partially removed instead of providing the nickel foil piece as the polymerization starting point. It was produced and the same measurement was performed. 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 solid electrolytic capacitor according to the present invention is far superior.

(Embodiment 2) Next, a second embodiment of the method of manufacturing a laminated solid electrolytic capacitor according to the present invention will be described.

In this embodiment, when two aluminum etched foils are laminated, a separator for electrolytic capacitors is inserted as a separator between the etched foils. Any separator may be used as long as it can be impregnated with an electrolytic polymerization solution used for electrolytic polymerization, and synthetic fibers, glass fibers, and the like can be used in addition to plant fibers such as kraft and Manila hemp, which are commonly used as separator paper for electrolytic capacitors. Except for this, ten capacitors were manufactured in the same manner as in the first embodiment. The capacity, loss factor and leakage current at 120 Hz of the obtained solid electrolytic capacitor were measured. Furthermore, the impedance at 500 kHz was measured and the average value is shown in (Table 1). From this, it can be seen that the capacitor according to the present invention has very excellent characteristics.

(Embodiment 3) Next, a third embodiment of the method of manufacturing a laminated solid electrolytic capacitor according to the present invention will be described.

In this embodiment, immediately after the electrolytically polymerized polypyrrole is polymerized and formed, the projection portion provided with the nickel foil piece at the polymerization initiation portion is bent and removed, and then the cut surface of the capacitor element is covered with an ultraviolet curable resin. The insulating material for covering the cut surface of the capacitor element may be any material as long as it can be insulation-coated, and examples thereof include an ultraviolet curable resin, an epoxy resin, a polyimide, a polyimide amide, and a silicone rubber. Except for this, ten capacitors were manufactured in the same manner as in the first embodiment.
The capacity, loss factor and leakage current at 120 Hz of the obtained solid electrolytic capacitor were measured. Furthermore, 500 kHz
The impedance was measured and the average value is shown in (Table 1).
From this, it can be seen that the capacitor according to the present invention has very excellent characteristics.

(Embodiment 4) Next, a fourth embodiment of the method of manufacturing a laminated solid electrolytic capacitor according to the present invention will be described.

In this example, n-butyl phosphate was used in place of sodium triisopropylnaphthalene sulfonate. Except for this, ten capacitors were manufactured in the same manner as in the first embodiment. The capacity, loss factor and leakage current at 120 Hz of the obtained solid electrolytic capacitor were measured. Furthermore, the impedance at 500 kHz was measured and the average value is shown in (Table 1). From this, it can be seen that the capacitor according to the present invention has very excellent characteristics.

(Fifth Embodiment) Next, a fifth embodiment of the method for manufacturing a laminated solid electrolytic capacitor according to the present invention will be described.

In this example, pyrrole (0.5M),
An electrolytic solution containing thiophene (0.5M), sodium tetrabutylammonium paratoluenesulfonate (0.1M) and acetonitrile in place of the electrolytic solution for polymerization containing sodium triisopropylnaphthalenesulfonate (0.1M) and water. Was used. Other than that, 10 capacitors were manufactured in the same manner as in the (first) embodiment. The capacity, loss factor and leakage current at 120 Hz of the obtained solid electrolytic capacitor were measured. Further, the impedance at 500 kHz was measured and the average value is shown in Table 1. From this, it can be seen that the capacitor according to the present invention has very excellent characteristics.

The present invention is not limited to the compounds and processing steps of the above-mentioned examples. It goes without saying that substitutable compounds and treatment steps other than the exemplified ones may be used.

[0028]

As described above, in the method of manufacturing a laminated solid electrolytic capacitor according to the present invention, a part of dielectrics on two or more valve metal foils in which a dielectric film and manganese oxide are sequentially formed. By removing the body film to establish electrical continuity between the valve metals, stacking and fixing, electrolysis is carried out using the conductive part provided in contact with the valve metal with the dielectric film removed as the polymerization initiation part, and manganese oxide. Electrolytically polymerized conductive polymer film is laminated on top to cover and fix two or more valve metal foils, and then the polymerization initiation part is cut and removed, so by simply applying a voltage to the anode valve metal, The electrolytic polymer can be uniformly grown from the conductive portion provided in contact with the valve metal, and the grown conductive polymer can cover and fix at least two or more valve metals. Therefore, when the polymerization reaction is completed, it is already a laminated type, and a laminated solid electrolytic capacitor can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a method for manufacturing a laminated solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a process diagram illustrating a method of manufacturing a laminated solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 3 is a process sectional view illustrating a method for manufacturing a laminated solid electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

1 Aluminum Etched Foil 2 Dielectric film 3 Manganese oxide layer 4 Nickel foil pieces 5 carbon layer 6 Silver paste layer 7 Electropolymerized polypyrrole

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

Claims (6)

[Claims] 1. A part of the dielectric film on at least two valve metal foils on which a dielectric film and a manganese oxide are sequentially formed is removed to establish electrical continuity between valve metals and to fix them in layers. Electrolytic polymerization is performed by using a conductive portion provided in contact with the valve metal from which the dielectric film is removed as a polymerization initiation portion, and an electrolytically polymerized conductive polymer film is laminated on the manganese oxide.
A method for producing a laminated solid electrolytic capacitor, which comprises covering and fixing one or more valve metal foils, and thereafter cutting and removing the polymerization initiation portion. 2. A part of the dielectric film on at least two valve metal foils on which a dielectric film and a manganese oxide are sequentially formed is removed to establish electrical continuity between the valve metals and to laminate and fix them. The method of manufacturing a laminated solid electrolytic capacitor according to claim 1, wherein a separator is inserted between the valve metals. 3. The method for producing a laminated solid electrolytic capacitor according to claim 1, wherein the conductive portion serving as a polymerization initiation portion is a metal that is not anodized. 4. The method for producing a laminated solid electrolytic capacitor according to claim 1, wherein the cut surface of the capacitor element is covered with an insulating material after cutting and removing the polymerization initiation portion. 5. The electrolytically polymerized conductive polymer is obtained by electrolytically polymerizing at least one monomer selected from pyrrole, thiophene and derivatives thereof. A method of manufacturing the laminated solid electrolytic capacitor as described in. 6. The method for producing a laminated solid electrolytic capacitor according to claim 1, wherein the valve metal is aluminum or tantalum.