JPH0521294A - Manufacture of capacitor - Google Patents

Abstract

PURPOSE:To reduce a short-circuit failure rate and improve the mass-productivity by a method wherein the part of a conducting part which is so provided as to by brought into contact with the protrusion of an electrode is used as a polymerization starting part to perform electrolytic polymerization and an electrolytically polymerized polymer film is built up on a manganese oxide layer to form a facing electrode and then, the protrusion including the polymerization starting part is removed. CONSTITUTION:A dielectric film 3 and a manganese oxide layer 4 are successively formed on an electrode which has at least one protrusion along its surface direction. Then the part of the dielectric film 3 on the protrusion of the electrode is removed and a conductive part which is so provided as to be brought into contact with the exposed electrode part is used as a polymerization starting part 7 to perform electrolytic polymerization and an electrolytically polymerized conductive polymer film 5 is built up on the manganese oxide layer 4. After that, the protrusion including the conductive part used as the polymerization starting part 7 is removed. With this constitution, the polymerization starting part can be located easily and removed easily. As the capacity of the protrusion of the electrode is not included in a rated capacity, the rated capacity of the capacitor is not affected by the removal of the protrusion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a conductive polymer film for at least one of electrodes facing each other with a dielectric film interposed therebetween, and produces a capacitor having high reliability and excellent productivity. It is about the method.

[0002]

2. Description of the Related Art Recently, with the digitalization of electric equipment, the capacitors used therein have low impedance in the high frequency region, and there is an increasing demand for miniaturization and large capacity. Conventionally, plastic film capacitors, mica capacitors, laminated ceramic capacitors, etc. have been used as high frequency capacitors. Other examples include aluminum dry electrolytic capacitors, aluminum or tantalum solid electrolytic capacitors.

In an aluminum dry electrolytic capacitor, a liquid electrolyte is used by winding an etched aluminum foil for an anode and a cathode through a paper separator. In the case of aluminum or tantalum solid electrolytic capacitors, the electrolyte is solidified in order to improve the characteristics of the aluminum electrolytic capacitors. To form such a solid electrolyte, after immersing the anode foil in a manganese nitrate solution,
A manganese dioxide layer is formed by thermal decomposition in a high temperature furnace at around 0 ° C. In the case of this capacitor, since the electrolyte is a solid, there are no drawbacks such as volatilization of the electrolytic solution at high temperature and deterioration of the function caused by solidification at low temperature, and the frequency characteristics and temperature characteristics are better than those of the liquid electrolyte. In addition, 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. 58-1).
7609). Furthermore, there is a method in which a polymerizable monomer such as pyrrole, thiophene, or furan is electrolytically polymerized to form a conductive polymer, which is used for at least one of the electrodes of a capacitor, and a polyimide thin film serving as a dielectric is electrically charged on the electrode surface. Formed by the dressing method,
A capacitor formed by stacking a chemically polymerized conductive polymer film and further an electrolytically polymerized conductive polymer film is disclosed at the 58th Congress of the Electrochemical Society in the spring of 1991 (Abstracts P251 and P252).

[0005]

However, although various capacitors are used in this way, it is difficult to increase the capacity because the shape of the film capacitor and the mica capacitor becomes large, and the monolithic ceramic capacitor is small. Although it was born from the demand for large capacity, it has drawbacks such as extremely high price and poor temperature characteristics. Further, in the aluminum electrolytic capacitor, since the oxide film is easily damaged, it is necessary to apply an electrolyte between the oxide film and the cathode to repair the damage at any time. For this reason, a capacitor that uses a liquid electrolyte may cause a decrease in capacitance and an increase in loss over time due to electrolyte leakage and ionic conductivity. It has the disadvantage of large loss.

[0006] Next, the solid electrolyte itself will be described. For reasons such as damage to the oxide film due to thermal decomposition at high temperature several times and high specific resistance of manganese dioxide,
It cannot be said that the loss in the high frequency range is sufficiently small. Also, T
Solid electrolytic capacitors using organic semiconductors such as CNQ salts show superior high frequency characteristics compared to those using manganese dioxide, but there is an increase in specific resistance when applying organic semiconductors, and anode foils. It cannot be said that it exhibits ideal characteristics due to poor adhesion to the like.

Further, when a conductive polymer thin film is used as an electrode of a capacitor, the conductive polymer thin film is excellent as a counter electrode of an electrode having a dielectric film formed thereon, although it has excellent frequency characteristics, temperature characteristics, and life characteristics. In order to form it, a polymerization initiation conductive part is provided on the electrode having a dielectric film, and the conductive polymer film is laminated by performing electrolytic polymerization using this polymerization initiation conductive part as an anode, and then the conductive part which became the polymerization initiation part. When a polymerization initiation portion is provided in the electrode plane surrounded by the four sides in order to remove the portion including at least, it is difficult to remove the portion including at least the polymerization initiation portion. Further, if the polymerization initiation portion is provided at the corner of the electrode, the removal is easy, but there is a drawback that the capacity corresponding to the area where the corner is removed decreases and the rated capacity is not satisfied.

In view of the above-mentioned problems, the present invention is a small-sized, large-capacity capacitor having excellent frequency characteristics, in which it is easy to form and remove the polymerization initiation portion, there is no short-circuit failure and capacity reduction, and a capacitor with a small leakage current is used efficiently. The purpose is to provide well.

[0009]

To achieve this object, a method of manufacturing a capacitor according to the present invention comprises a dielectric film and a manganese oxide layer on the surface of an electrode having at least one projecting portion in the plane direction. After sequentially forming, the dielectric film and the manganese oxide layer are removed, and the electrode protrusion is used as the electrode portion, and the conductive portion provided in contact therewith is used as a polymerization initiation portion for electrolytic polymerization to perform manganese oxide. An electrolytic polymerization conductive polymer film is laminated on the layer to form a counter electrode, and the protruding portion including at least the polymerization initiation portion is removed later.

[0010]

According to the present invention, the above structure makes it easy to position and remove the polymerization initiation portion, and since the capacity of the protruding portion of the electrode is not included in the rated capacity, a capacitor that satisfies the rated capacity even if removed is provided. it can.

[0011]

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

(First Embodiment) A first embodiment will be described below with reference to the drawings, taking as an example the case where the method for manufacturing a capacitor according to the present invention is applied to an aluminum electrolytic capacitor.

1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are manufacturing process diagrams in this embodiment. In FIGS. 1 to 4, (a) is a side view and (b) is a front view. First, a heat-resistant insulating tape 8 was attached to the surface of the valve metal 2, and the smaller area was used as the anode lead mounting surface, and the larger area (4 mm x
5 mm) was used as the dielectric film formation surface.

As shown in FIG. 1, a valve action metal foil 2 (aluminum etched foil) provided with a protrusion having a width of 1 mm and a length of 3 mm in a plane direction was prepared at 70 ° C. and 40 ° C. using a 7% ammonium adipate aqueous solution. Anodizing was performed under a condition of an applied voltage of 42 V for a minute to form the dielectric film 3. Next, a manganese nitrate aqueous solution was applied to this, and thermally decomposed at 300 ° C. for 20 minutes to form a conductive layer made of the manganese oxide film 4. Then, a nickel foil piece having a diameter of 1 mm and a thickness of 50 μm was provided on the manganese oxide film 4 by welding to form a polymerization initiation conductive portion 7.

Next, the valve metal foil was dipped in an electrolytic polymerization solution consisting of pyrrole (0.25M), triisopropylnaphthalene sulfonate (0.1M) and water, and the nickel foil piece was placed in the polymerization initiation portion conductive portion. 7, a constant voltage of 2.5 V was applied for 30 minutes, and as shown in FIG. 3, a conductive polymer film 5 (polypyrrole film) for counter electrode was formed on the manganese oxide 4.
Was formed.

Subsequently, as shown in FIG. 4, the valve metal foil 2, the dielectric film 3, the manganese oxide film 4, and the conductive polymer film 5 above and below the protruding portion including at least the polymerization initiation conductive portion 7 are formed. It was bent and removed together. Then, as shown in FIG. 5, an anode lead 1 and a cathode lead 6 were provided to obtain a capacitor. The characteristics of the capacitor thus manufactured are shown in (Table 1).

[0017]

[Table 1]

(Comparative Example) Instead of the protrusion of 1 mm in width and 3 mm in length provided on the electrode in Example 1, the width of the protrusion is 4 mm.
Comparative capacitors were produced in the same manner as in Example 1 except that the length was set to 3 mm, and the characteristics of the produced capacitors are shown in (Table 1).

As is clear from (Table 1), the capacitor according to the present embodiment has a remarkably low short circuit defect rate, a small loss, and an excellent effect as compared with the capacitor according to Comparative Example 1.

As described above, according to the present embodiment, the polymerization initiation conductive portion 7 is provided on the protruding portion of the electrode having a width of 1 mm and a length of 3 mm to form the conductive polymer film on the dielectric film. After
Since the protruding portion including at least the polymerization initiating conductive portion is removed, there is no short circuit defect and loss defect, and low leakage current can be realized.

In this embodiment, an electrolytic capacitor having a valve metal as an electrode and an anodic oxide film as a dielectric has been described, but other types of capacitors also use an electrolytically polymerized conductive polymer as an electrode. Needless to say, it is included.

Further, in the examples, only the case where manganese oxide is formed by using manganese nitrate is described, but not limited to manganese nitrate, other materials can be used as long as they can form manganese oxide. . Further, in the examples, it was described that the nickel foil was welded to the anode and brought into contact with it to be used for the polymerization initiation portion, but not limited to nickel, any other conductive material which is not anodized may be used. Further, the contacting method is not limited to welding, but other methods such as caulking can be used. Further, in the present embodiment, only the shape of the protruding portion is rectangular, but other shapes such as a triangle and a semicircle may be used. It is also a preferable aspect to provide a notch for facilitating removal of the protruding portion.

Example 2 A capacitor was manufactured in the same manner as in Example 1 except that the width of the protruding portion was 3 mm, and the characteristics of the capacitor according to the example are shown in (Table 1).

As is clear from (Table 1), the capacitor manufactured according to the present embodiment with the protrusion having the polymerization initiation portion having a width of 3 mm has a short circuit defect rate in comparison with the comparative example having a width of 4 mm. An excellent effect is obtained in that the loss is low and there is no loss.

(Embodiment 3) As shown in FIG. 6, the same as Embodiment 1 except that the projections (width 1 mm, length 5 mm) of the electrodes 1 and 2 are connected in common. , A capacitor was manufactured. The characteristics of the capacitor according to this example are shown in (Table 1).

As is clear from (Table 1), the capacitor according to the present embodiment, in which the conductive polymer film was simultaneously formed on the two electrodes with the common protruding portion provided with the polymerization initiation portion, was prepared in the same manner as in the first embodiment. In addition, the short-circuit defect rate is low, there is no loss defect, and the electrolytic polymerization conductive polymer film can be formed on the two anode foils at one polymerization initiation portion, which is an excellent effect.

Example 4 As shown in FIG. 7, a capacitor was produced in the same manner as in Example 1 except that two protruding portions (width 1 mm, length 3 mm) of electrodes were provided. The characteristics of the capacitor according to this example are shown in (Table 1).

As is clear from (Table 1), the capacitor manufactured according to this embodiment with two protrusions provided with the polymerization initiation portion has a low short-circuit defect rate and no loss defect as in Example 1. Further, since there are two polymerization initiation portions, an excellent effect can be obtained in that the electrolytic polymerization conductive polymer film can be rapidly formed.

[0029]

As described above, according to the present invention, a dielectric film is formed on an electrode having a protrusion in the planar direction, and a manganese oxide layer is formed on the dielectric film. Since the electropolymerized conductive polymer film was laminated on the manganese oxide layer by electrolytic polymerization provided with the initiation portion, and then the protruding portion including at least the polymerization initiation portion was removed.
The formation and removal of the polymerization initiation portion are easy, and there is no short circuit failure or capacity reduction, and a capacitor with a small leakage current can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a side view and a front view of a valve action metal having a protruding portion, showing the steps of a method for manufacturing a capacitor according to an embodiment of the present invention.

FIG. 2 shows steps of a method of manufacturing a capacitor in the same example, in which a valve metal, a dielectric film, a manganese oxide film,
A side view and a front view in which a polymerization initiation conductive portion is formed.

FIG. 3 shows steps of a method of manufacturing a capacitor in the same example, in which a valve metal, a dielectric film, a manganese oxide film,
Polymerization initiation conductive part, side view and front view with conductive polymer film formed

FIG. 4 is a side view and a front view showing the steps of the method for producing the capacitor in the example, in which the polymerization initiation conductive portion is removed.

FIG. 5 is a plan view of a capacitor manufactured by the method for manufacturing a capacitor according to the embodiment.

FIG. 6 is a front view showing a method of manufacturing a capacitor according to a third embodiment of the present invention.

FIG. 7 is a front view showing a method of manufacturing a capacitor according to a third embodiment of the present invention.

[Explanation 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 conductive part 8 Heat-resistant insulating tape

   ─────────────────────────────────────────────────── ─── 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 in which a dielectric film and a manganese oxide layer are sequentially formed on an electrode surface having at least one projecting portion in a plane direction, and then the dielectric film and the manganese oxide layer are removed. Electrode polymerization is performed by using a protruding portion of the electrode as a part and a conductive portion provided in contact with the electrode as a polymerization initiation portion, and laminating an electrolytically polymerized conductive polymer film on the manganese oxide layer to form a counter electrode, A method for manufacturing a capacitor, characterized in that a protruding portion including at least the polymerization initiation portion is removed later. 2. The method for producing a capacitor according to claim 1, wherein the electrode provided with at least one projecting portion in the planar direction is a valve metal. 3. The method of manufacturing a capacitor according to claim 1, wherein the length of the side of contact between the electrode and the protrusion provided in the plane direction is 3 mm or less. 4. The electropolymerized conductive polymer film is pyrrole,
The method of manufacturing a capacitor according to claim 1, wherein the capacitor is formed in a solution containing at least one of thiophene or a derivative thereof and a supporting electrolyte. 5. The method for producing a capacitor according to claim 1, wherein the anode valve metal is one selected from aluminum and tantalum.