JP2924252B2 - Method for manufacturing solid electrolytic 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 solid electrolytic capacitor using a conductive polymer film as a solid electrolyte and having particularly low leakage current characteristics and excellent productivity.

[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-type solid electrolytic capacitor, an etched positive and negative aluminum foil is wound up through a paper separator, and a liquid electrolyte is used.

Further, 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. The anode foil is immersed in a manganese nitrate solution at 350 ° C. to form this solid electrolyte.
Pyrolyze in high and low temperature furnaces 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. Aluminum electrolytic capacitors, like tantalum electrolytic capacitors, can achieve a large capacity because an oxide film serving as a dielectric can be made very thin.

Further, in recent years, a solid electrolytic capacitor using an organic semiconductor such as a 7,7,8,8-tetracyanoquinodimethane (TCNQ) salt as a solid electrolyte has been developed (Japanese Patent Laid-Open No. Sho 58-17609). Gazette). Also pyrrole,
There is also a method in which a polymerizable monomer such as furan is electrolytically polymerized to form a conductive polymer, which is used as a solid electrolyte (JP-A-60-244017).

[0005]

As described above, various types of capacitors are used. However, film capacitors and mica capacitors have large shapes because of their large shapes. However, there are problems such as an extremely high price and poor temperature characteristics. In addition, since the aluminum electrolytic capacitor is easily damaged by the oxide film, it is necessary to repair the damage by applying an electrolyte between the oxide film and the cathode as needed. 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 cannot be said to be sufficiently small because the oxide film is damaged by thermal decomposition several times at a high temperature and the specific resistance of manganese dioxide is high. Also, TCN
Solid electrolytic capacitors using organic semiconductors such as Q salt
It shows excellent high-frequency characteristics compared to those using manganese dioxide, but shows ideal characteristics due to the increase in specific resistance when applying organic semiconductors, weak adhesion to anode foil, etc. I can't say. Further, when the conductive polymer thin film is used as a solid electrolyte, frequency characteristics, temperature characteristics, life characteristics, and the like are excellent. However, in order to form a conductive polymer thin film as a solid electrolyte on the anode valve metal, the solid electrolytic capacitor is provided with a polymerization initiation conductive part on the anode valve metal foil having a dielectric film, and the polymerization initiation conductive part is provided. Electrolytic polymerization is performed with the anode as the anode, and the conductive polymer film is laminated.However, the electrolytic polymerization is often performed in a state where the anode valve metal foil is set up vertically, and if the position where the polymerization initiation conductive part is provided is low, the polymerization initiation part is Since the oligomer formed in step (1) drops due to the high density, it does not adhere to the surface of the anode valve metal foil located at a position higher than the starting portion, and the polymerization time is slow because the effect of promoting the formation of the polymer film by the oligomer cannot be obtained. There is a problem that the film near the point becomes thick and the resistance increases.

[0007]

A method of manufacturing a solid electrolytic capacitor according to the present invention comprises forming an insulator on the surface of an anode valve metal foil, dividing the surface, and forming a dielectric film on one surface by anodization. Forming a manganese oxide layer thereon, removing the dielectric film at least at one location near the insulator on the surface on which the manganese oxide layer is formed, exposing the metal part, A conductive portion is provided by contacting the metal portion, and the surface of the anode valve metal foil on which the conductive portion is formed is immersed until the insulator matches the interface of the electrolytic polymerization solution,
Electroconductive polymerization is performed using the conductive portion as a polymerization initiation portion, and an electropolymerized conductive polymer film is uniformly and quickly laminated on the manganese oxide layer.

[0008]

According to the present invention, since the polymerization initiation portion is provided on the anode valve metal foil immersed in the electrolytic polymerization solution as described above, the oligomer formed during the polymerization at the polymerization initiation portion drops due to the high density. In order to promote the growth of the electropolymerized conductive polymer film by adhering to the surface of the anode valve metal foil, it can be laminated on the entire surface of the anode valve metal foil in a short time, and the film thickness becomes thin and uniform, and the electric resistance of the film Does not increase, and a solid electrolytic capacitor with small loss can be obtained.

[0009]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIGS. 1, 2, 3, 4, 5, and 6 are views showing the manufacturing process of this embodiment. FIG. 1 (a) side view,
As shown in the front view of FIG. 1 (b), an insulator, for example, a heat-resistant insulating tape 11 (polyimide tape) is formed on the surface of the valve action metal foil 2 (aluminum-etched foil) to prepare a divided surface. One surface was treated with a 7% aqueous ammonium adipate solution at about 70 ° C. for 40 minutes with an applied voltage of 42%.
Anodize under the condition of V to form a dielectric film 3;
A manganese nitrate aqueous solution is applied and thermally decomposed in a constant temperature and humidity of 85% at 300 ° C. for 20 minutes to form a conductive layer composed of the manganese oxide film 4. 1 mm, thickness 50 μm) was placed on the manganese oxide film 4 by welding, and as shown in FIG. 2, an electrolytic polymerization solution comprising pyrrole (0.25 M), triisopropylnaphthalene sulfonate (0.1 M), and water 9 is immersed in the surface of the valve metal foil 2 on which the dielectric film 3 and the like are formed, and fixed at a place where the heat-resistant insulating tape 11 coincides with the interface of the electrolytic polymerization solution 9. In the figure, 12 is an anode,
Reference numeral 13 denotes a cathode.

Here, a constant voltage of 2.5 V is applied for 30 minutes, and as shown in FIG. 3A, a partially crushed side view, and FIG. A polymer film 5 (polypyrrole film) was formed.

Subsequently, as shown in FIG. 4 (a) side view and FIG. 4 (b) front view, a portion including at least the polymerization initiation conductive portion 10 was bent and removed. Next, as shown in FIG. 5 (a), a partially crushed side view, and FIG. 5 (b), a front view, a carbon paint film 6 and a silver paint film 7 are formed except for the cross section.
Finally, as shown in FIG.
Was provided and packaged with a resin to obtain a solid electrolytic capacitor.

The characteristics of the solid electrolytic capacitor prepared by placing the polymerization initiation conductive part according to the present embodiment on the anode valve metal foil immersed in the polymerization solution, and, as a comparative example, the polymerization initiation conductive part in the polymerization solution, Table 1 shows the initial characteristics and Table 2 shows the thickness of the formed conductive polymer film of the solid electrolytic capacitor produced by placing it below the immersed anode valve metal foil. As is clear from Tables 1 and 2, the solid electrolytic capacitor according to the present example has excellent effects in that the polymerization time is short, the film thickness is thin, uniform, and loss is small.

[0014]

[Table 1]

[0015]

[Table 2]

As described above, according to the present embodiment, the polymerization initiation conductive portion is provided on the anode valve metal foil immersed in the polymerization solution to form the conductive polymer film. The loss can be reduced because the film thickness is uniform.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 7, it is the same as Example 1 except that two polymerization initiation conductive portions 10 are provided. According to this example, the polymerization time was 20 minutes, and the time was able to be shortened by about 30% as compared with Example 1. Table 1 shows the characteristics of the solid electrolytic capacitor produced by installing the polymerization initiation conductive part 10 according to the present embodiment at two places on the anode valve action metal foil 2 immersed in the polymerization solution. As is clear from Table 1, the solid electrolytic capacitor according to the present example has an excellent effect in that the polymerization time is short and the loss is small.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 8, it is the same as Example 1 except that a bridge connecting between the anode valve action metal foils 2 is provided, and the polymerization initiation conductive portion 10 is installed in the bridge portion to perform electrolytic polymerization. 2 from one starting point
A conductive polymer film 5 (polypyrrole film) was formed on the three anodes in a polymerization time of 35 minutes. The characteristics of the solid electrolytic capacitor manufactured by providing a bridge connecting the anode valve action metal foils 2 according to the present embodiment and installing the polymerization initiation conductive portion on the bridge portion of the anode valve metal foil immersed in the polymerization solution are shown in FIG. This is shown in 1). As is clear from (Table 1),
In the solid electrolytic capacitor according to the present embodiment, an excellent effect can be obtained in that the polymerization initiation conductive portion can be reduced, the polymerization time is short, and the loss is small.

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

In the above embodiment, the nickel foil was welded to the anode and brought into contact with the anode to be used for the polymerization initiation part. However, the invention is not limited to nickel, and any other conductive material which is not anodized may be used. is there.

Further, the contact method is not limited to welding, and other methods such as caulking can be used. Although only the case where a polyimide tape is used as the insulating partition means has been described, other insulating tapes such as Kapton or a resist can be used instead of the polyimide tape.

[0023]

As described above, according to the present invention, the surface of the anode valve metal foil is divided by means of an insulating partition, a dielectric film is formed on one surface by anodization, and manganese oxide is formed thereon. Forming a conductive layer by contacting the metal part from which the dielectric film has been removed at least at one or more places near the insulator on the surface on which the manganese oxide layer has been formed; Immerse the surface where the conductive part of the foil is formed until the insulator partitioning means coincides with the interface of the electrolytic polymerization solution,
Since the solid electrolytic capacitor is formed by laminating an electropolymerized conductive polymer film on the manganese oxide layer by electrolytic polymerization using the conductive portion as a polymerization initiator, the growth of the electropolymerized conductive polymer film is rapid. Thus, a solid electrolytic capacitor having uniform and small loss can be efficiently produced.

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

In the above embodiment, the nickel foil was welded to the anode and brought into contact with the anode to be used for the polymerization initiation part. However, the invention is not limited to nickel, and any other conductive material which is not anodized may be used. is there.

Further, the contact method is not limited to welding, and other methods such as caulking can be used. Although only the case where a polyimide tape is used as the insulating partition means has been described, other insulating tapes such as Kapton or a resist can be used instead of the polyimide tape.

[Brief description of the drawings]

FIG. 1 is a process diagram of forming an insulator on a valve metal foil used in a method for manufacturing a solid electrolytic capacitor according to a first embodiment of the present invention.

FIG. 2 is a process chart showing an electropolymerization process in the example.

FIG. 3 is a process diagram of forming a conductive polymer film by electrolytic polymerization in the same example.

FIG. 4 is a process diagram of the embodiment in which a polymerization initiation conductive portion is removed.

FIG. 5 is a process diagram of forming a carbon paint film and a silver paint film on a conductive polymer film in the same example.

FIG. 6 is a plan view of the solid electrolytic capacitor in the embodiment.

FIG. 7 is a process diagram in which two polymerization initiation conductive portions used in the method for manufacturing a solid electrolytic capacitor according to the second embodiment of the present invention are installed.

FIG. 8 is a process diagram in which a bridge for connecting anode valve action metal foils used in the method for manufacturing a solid electrolytic capacitor according to the third embodiment of the present invention is provided, and a polymerization initiation conductive portion is provided in the bridge portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode lead 2 Valve action metal foil 3 Dielectric film 4 Manganese oxide film 5 Electropolymerized conductive polymer film 6 Carbon paint film 7 Silver paint film 8 Cathode lead 9 Electropolymerized solution 10 Polymerization start conductive part 11 Heat resistant insulating tape

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshinari Nanai 3-1-1 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa Prefecture Matsushita Giken Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H01G 9/02 H01G 9/24

Claims (3)

(57) [Claims] An anode valve metal foil having a surface divided by an insulator partitioning means, a dielectric film formed on one surface by anodic oxidation, and a manganese oxide layer formed thereon; A conductive portion formed by removing at least one portion of the dielectric film and exposing the valve metal, and contacting the exposed valve metal in the vicinity of the insulator on the surface where the layer is formed; The conductive portion of the metal foil is immersed until the insulator partitioning means coincides with the interface of the electrolytic polymerization solution, and the conductive portion is electrolytically polymerized as a polymerization initiator, and an electropolymerized conductive polymer film is formed on the manganese oxide layer. A method for manufacturing a solid electrolytic capacitor, comprising laminating. 2. The solid electrolyte according to claim 1, wherein the electropolymerized conductive polymer film is formed in an electropolymerization solution containing at least one of pyrrole, thiophene or a derivative thereof and a supporting electrolyte. Manufacturing method of capacitor. 3. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the anode valve metal is one selected from aluminum or tantalum.