JPH06168851A - Solid-state electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To make it possible to form an electrolytic polymerization film to the center of a capacitor element smoothly, by using a capacitor element in which a film of a conductive polymer such as polypyrrole or polyaniline is interposed between metal foils and is wound. CONSTITUTION:A film 6 of a conductive polymer such as polypyrrole, polyaniline, polythiophene or polyfuran is interposed between an anode foil 2 and a cathode foil 4 having a valve function such as aluminum, tantalum or niobium on which an oxide film is formed and is wound, and a capacitor element 1 is formed, and further the film 6 of the conductive polymer is previously installed in the proximity of the center of the capacitor element 1. Then, the film 6 of the conductive polymer is used for a supply of an electrolytic polymerization current, and an electrolytic polymerization film such as polypyrrole or polyaniline is smoothly formed to the center of the capacitor element 1, and a solid electrolytic capacitor with a good occurrence rate of electrostatic capacity can be implemented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor using a conductive polymer as an electrolyte and a method for producing the same. More specifically, the conductive polymer film is wound between negative and positive foils and wound. The present invention relates to a solid electrolytic capacitor that does.

[0002]

2. Description of the Related Art As shown in FIG. 3, the prior art includes a cathode foil (4) and an anode foil (2) having a valve action of aluminum, tantalum, niobium, etc., on which an oxide film (dielectric layer) is formed in advance. A separator paper (8) made of Manila hemp or the like is inserted between the two and wound to form a capacitor element (1), and the element (1) is immersed in an oxidizing agent such as ammonium persulfate or diluted sulfuric acid. Chemical reaction treatment is performed in the vapor phase and liquid phase of pyrrole monomer, aniline monomer, etc. to form a chemically polymerized film of polypyrrole, polyaniline, etc.
In the next step, an external power supply electrode such as a nickel wire, a platinum wire, or a stainless wire is directly contacted with this chemically polymerized film in an electrolytic solution of pyrrole / ethanol system, pyrrole / sulfonic acid system, etc., and electrolytic polymerization current is supplied to electrolyze. Polymerization is performed to form an electrolytically polymerized film of polypyrrole, polyaniline, or the like, which has higher heat resistance and higher molecular density, and is packaged in the final step to form a capacitor.

In addition to the above-mentioned conventional techniques, a capacitor element obtained by simultaneously winding an anode foil and a separator paper without using a cathode foil is used to electrolyze polypyrrole, polyaniline, etc., which is produced through the same steps as described above. There is also a capacitor in which a cathode lead-out layer is provided on a polymer film to draw out a cathode terminal and which is then packaged in the final step.

However, such a conventional capacitor is
Since the structure of the capacitor element (1) is a winding type, impregnation with an oxidant, a pyrrole monomer, an aniline monomer, etc. is not sufficiently performed during the chemical polymerization, and a chemical polymerization film is formed especially near the central part of the winding part of the capacitor element. Is not sufficiently formed, and the formation of the electrolytically polymerized film is adversely affected even in the subsequent electrolytic polymerization step, so that the appearance rate of the capacity is very poor, which causes poor characteristics.

[0005]

When the structure of the capacitor element is of the winding type, during the chemical polymerization treatment of polypyrrole, polyaniline, etc., the oxidizing agent, the pyrrole monomer, the aniline monomer, etc. are in the vicinity of the contact portion with the capacitor element. Since it exists only in the element head portion and the element outer peripheral portion, the formation of the chemically polymerized film by this chemical reaction does not proceed sufficiently to the central portion of the capacitor element. Therefore, it adversely affects the formation of the electrolytic polymerized film in the next step based on the chemically polymerized film, and the appearance rate of the capacity of the capacitor is very poor, resulting in poor characteristics.

[0006]

As described above, the present invention uses a film of a conductive polymer such as polypyrrole or polyaniline in order to solve the incompleteness of the formation of the chemically polymerized film near the central portion of the conventional capacitor element. By doing so, the chemical polymerization step (that is, the step of forming a chemically polymerized film of polypyrrole, polyaniline or the like using an oxidizing agent and a pyrrole monomer, an aniline monomer, etc.) that causes the above-mentioned characteristic failure is deleted. . That is, since the conductive polymer film is disposed in the central portion of the wound type capacitor element, the formation of the electrolytically polymerized film efficiently proceeds to the central portion of the capacitor element, the appearance rate of capacitance is good, and the characteristics are Be improved.

In this case, a conductive polymer film is used as a base for supplying an electropolymerization current during the electropolymerization.

[0008]

[Function] A film of a conductive polymer such as polypyrrole or polyaniline is inserted and wound between a cathode foil and an anode foil having a valve action such as aluminum, tantalum, niobium and the like on which an oxide film (dielectric layer) is formed. Thus, a capacitor element is formed, and a conductive polymer film is previously disposed near the center of the capacitor element. Then, this conductive polymer film can be used to supply an electrolytic polymerization current, and an electrolytic polymerization film of polypyrrole, polyaniline or the like can be smoothly formed up to the central portion of the capacitor element.

[0009]

【Example】

[Part 1] Next, an embodiment of the present invention will be described. Figure 1
Shows a capacitor element (1) used in the present invention, and (2) is an anode foil of etched aluminum on which an oxide film (dielectric layer) is formed and has a thickness of about 60 to 90.
μm. (3) is an anode lead-out terminal. (4) is a cathode foil made of an aluminum foil having a thickness of about 60 to 90 μm. (5) is a cathode lead-out terminal. (6) is about 5
It is a film of a conductive polymer of 0 μm polypyrrole. A conductive polymer film (6) is inserted between the anode foil (2) and the cathode foil (4) and wound to form a capacitor element (1).

As shown in FIG. 3, this capacitor element (1) is immersed in an aqueous electrolytic solution containing 0.2 mol / l of pyrrole monomer and 0.06 mol / l of naphthalenesulfonic acid (dopant). Then, the conductive polymer film (6) is brought into contact with an external power feeding electrode made of a stainless wire (7) having a diameter of about 0.3 mm, and the electrolytic polymerization current is adjusted to the size of the capacitor element (1), and the value is adjusted to about 30 to 120. By supplying power for a minute, the electrolytically polymerized film of polypyrrole is smoothly formed up to the central portion of the capacitor element. Then, this capacitor element is packaged in the final step to manufacture a solid electrolytic capacitor.

[Part 2] The capacitor element (1) was used in Example [Part 1] in an acetonitrile-based electrolytic solution containing pyrrole monomer 0.2 mol / l and paratoluene sulfonic acid (dopant) 0.1 mol / l. Electrolytic polymerization is carried out by the same means as shown to manufacture a solid electrolytic capacitor.

[Conventional Example] FIG. 3 is a perspective view of a conventional solid electrolytic capacitor element (1). That is, an anode foil (2) made of an etched aluminum foil having a thickness of about 60 to 90 μm and having an oxide film (dielectric layer) having an anode lead terminal (3) and an aluminum foil having a cathode lead terminal (5). The separator element (8) made of Manila hemp or the like is interposed between the cathode foil (5) and the
Is formed. This capacitor element is hydrogen peroxide water /
It is dipped in an oxidizing agent of sulfuric acid (20/3 wt%) for 5 to 10 minutes, and then chemically reacted for several minutes in the vapor phase of the pyrrole monomer and in the liquid phase to form a chemically polymerized film of polypyrrole. Thereafter, this capacitor element (1) is subjected to electrolytic polymerization by the same means as in Example [No. 1] to manufacture a solid electrolytic capacitor.

Table 1 shows a comparison between the present embodiment [No. 1] and the conventional example. The measured value is a value measured at 120 Hz for a finished product using an element for 4.7 μF / 16 WV.

[0014]

[Table 1]

As can be seen from the above table, the embodiments of the present invention are extremely effective in improving the characteristics (mainly the capacitance characteristics) as compared with the conventional examples.

In the above-mentioned Examples [1] and [2], the capacitor element obtained by simultaneously winding the anode foil and the cathode foil with the polypyrrole film interposed therebetween is used. The present invention is not limited to this, but a cathode element is not used, but a capacitor element obtained by winding an anode foil and a polypyrrole film at the same time is used. The same effect can be obtained in a solid electrolytic capacitor in which the cathode terminal is pulled out and is packaged in the final step.

[0017]

As described above, when the capacitor element in which the film of the conductive polymer of the present invention is wound together with the electrode foil is used, it is not necessary to carry out the chemical polymerization process of polypyrrole, polyaniline, etc., and the manufacturing process is drastically reduced. It is possible to reduce the number, and moreover, it is possible to smoothly form an electrolytically polymerized film such as polypyrrole or polyaniline to the central part of the capacitor element.
It is possible to realize a solid electrolytic capacitor having various characteristics (especially the appearance rate of capacitance).

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a capacitor element.

FIG. 2 is a drawing showing a power supply state in electrolysis polymerization.

FIG. 3 is a view showing a conventional capacitor element.

[Explanation of symbols]

 1 Capacitor Element 2 Anode Foil 3 Anode Lead Terminal 4 Cathode Foil 5 Cathode Lead Terminal 6 Conductive Polymer Film 7 Stainless Wire 8 Separator Paper

Claims (2)

[Claims] 1. A solid electrolytic capacitor using a capacitor element in which a film of a conductive polymer such as polypyrrole, polyaniline, polythiophene, or polyfuran is inserted between metal foils and wound. 2. A capacitor element in which a film of a conductive polymer such as polypyrrole, polyaniline, polythiophene, polyfuran, etc. is wound between metal foils and wound, and the film of the conductive polymer is used as a feeding electrode during electrolytic polymerization. Method for manufacturing solid electrolytic capacitor used.