JPH02308517A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a capacitor wherein an electrolytically polymerized film can be formed without damaging a film oxide or a chemically polymerized film by performing electrolytic oxidative polymerization with carbon paper as a power supply electrode so as to form an electrolytically polymerized film on a required chemically polymerized film. CONSTITUTION:If an anode foil 3, where an anode lead 1 is mounted to a high purity of Al film made of film formative metal and a chemically polymerized film 2 is formed on the surface by chemical oxidative polymerization, and separator paper 4 are laminated and wound, it becomes a capacitor element 5. Next, when the element 5 is attached to an Al plate 6 and electrolytic oxidative polymerization is performed in electrolyte 7 with saw-shaped carbon paper 9 inside an electrolytic vessel 10 as a power supply electrode, an electrolytically polymerized film of solid electrolyte is formed on the surface of the film 2 of the element 5 and a solid electrolytic capacitor is made. By use of this carbon paper, an electrolytically polymerized film is formed without damaging the oxide film chemically polymerized film, and it becomes a good quality of solid electrolytic capacitor.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention provides a power supply means during electrolytic oxidative polymerization to form an electrolytic polymerized film on a chemically polymerized film formed on the surface of a dielectric oxide film. The present invention relates to a method for manufacturing a solid electrolytic capacitor that is an improved solid electrolytic capacitor.

(Prior Art) In general, a solid electrolytic capacitor using a solid electrolyte formed by electrolytically oxidizing and polymerizing a polycyclic compound such as virol on an oxide film formed on the surface of a film-forming metal is used. Some of these are disclosed in JP-A-60-244017 or JP-A-63-181308.

The techniques disclosed in these publications involve chemically converting an anode body with a roughened surface to form an oxide film, using this anode body as an anode, immersing it in an electrolytic solution and energizing it, and forming an electrolytic polymer film on the oxide film. However, since the oxide film is an insulator, it does not conduct electricity effectively with the cathode, and the current concentrates in the defective parts of the oxide film or in areas close to the cathode, resulting in a uniform electropolymerized film. It was extremely difficult to obtain

In particular, in order to increase capacitance, the surface area of the anode body is increased, or in the case of a sintered element made by sintering powder,
It was remarkable.

Therefore, a chemically polymerized film is formed in advance on the oxide film of the anode body by chemical oxidative polymerization, and a metal such as a platinum wire, nickel wire, or stainless steel wire is brought into contact with the chemically polymerized film as a power supply electrode, and electricity is applied in an electrolytic solution. By performing electrolytic oxidative polymerization, an effective electrolytically polymerized film is formed.

However, the platinum wire used as the power supply electrode.

Since metals such as nickel wire or stainless steel wire are hard, the oxide film and chemical polymer film are easily damaged when they come in contact with them.
This method has the risk of increasing leakage current and short-circuiting, and cannot necessarily be said to be an effective means.

(Problems to be Solved by the Invention) As described above, the conventionally disclosed means have resulted in problems to be solved in obtaining a desired electrolytically polymerized membrane.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor that can form an excellent electrolytic polymer film that becomes a solid electrolyte without damaging the oxide film or chemical polymer film. This is the purpose.

[Structure of the Invention] (Means for Solving the Problems) The method for manufacturing a solid electrolytic capacitor of the present invention includes forming a chemically polymerized film by chemical oxidative polymerization on an oxide film formed on a film-forming metal surface, and then A method for manufacturing a solid electrolytic capacitor in which an electrolytic polymerized film is formed on a chemically polymerized film by electrolytic oxidative polymerization, characterized in that carbon paper is used as a power supply electrode in the electrolytic oxidative polymerization.

(Function) According to the above configuration, the carbon paper used as a power supply electrode in electrolytic oxidative polymerization is soft, so even if it comes into contact with an oxide film or a chemically polymerized film, it can be efficiently carried out without damaging the oxide film or chemically polymerized film. It can contribute to the formation of electrolytic polymerized membranes.

(Example) Hereinafter, the present invention will be explained with reference to the drawings.

That is, as shown in FIG. 3, an anode lead 1 is attached to a high-purity aluminum foil on which an oxide film is formed, and an anode foil 3 on which a chemically polymerized film 2 is formed on the surface by chemical oxidation polymerization and a separator paper 4 are laminated. A wound capacitor element 5 is obtained.

Next, this element 5 is reformed to repair the oxide film.
Thereafter, as shown in FIG. 4, a plurality of capacitor elements 5 are successively attached via, for example, an aluminum plate 6, and the bottom of the capacitor elements 5 is soaked in an electrolytic solution as shown in FIGS. 1 and 2. The saw blade portion of the carbon paper 9 is placed in the electrolytic cell 10 in which a carbon paper 9 is placed in which carbon paper 9 is placed, and is coated and fixed with a solvent-resistant resin 8 leaving the tip at the bottom and processed into a saw blade shape. Electrolytic oxidative polymerization is carried out by contacting the capacitor element 5 to form an electrolytically polymerized film as a solid electrolyte on the surface of the chemically polymerized film 2 constituting the capacitor element 5. 11 in the diagram
is the external cathode.

Then, the capacitor element with the electrolytically polymerized film is coated with colloidal carbon, for example, to form a carbon layer, and then silver paste is applied to form a conductive coating, and the cathode lead is taken out from a part of it and placed in the case. A solid electrolytic capacitor is obtained by sealing.

According to the manufacturing method of the solid electrolytic capacitor having the above configuration, since the soft carbon paper 9 is used as the power supply electrode in electrolytic oxidation polymerization, even if it comes into contact with the oxide film or chemical polymer film, the oxide film or chemical polymer film It is extremely effective in preventing deterioration of leakage current characteristics and short-circuit failure without damaging the circuit.

Next, a solid electrolytic capacitor obtained by the present invention,
A comparison of the characteristics of solid electrolytic capacitors obtained by conventional methods using metal wires as power supply electrodes will be described. That is, the table shows Example 1 shown below. This figure shows a comparison of characteristics between Example 2 and a conventional example.

All samples are rated at 25V-15μF.

Example 1 (1) Anode foil A high-purity aluminum foil with a thickness of 60μ7W, a width of 3M, and a length of 50H.

(2) Chemical oxidation polymerization conditions After 5 minutes immersion in a 2 mol/41 pyrrole/ethanol solution, 5 minutes in a 0.5 mO+/41 17 ammonium persulfate aqueous solution.
Soak for minutes.

(3) Electrolytic oxidative polymerization conditions - Electrolytic solution Immersed in an electrolytic solution consisting of acetonitrile containing 1 mol/j of virol monomer and 1 mol, 1 of sodium para-toluenesulfonate as a supporting electrolyte, and subjected to constant current oxidative polymerization (177 LA/cd, 30 minutes).

The power supply electrode is made from paper made of carbon Il miscellaneous material, with a density of 0.1 to 0.2 and a conductivity of 4 to 7Sα-1. Carbon paper consisting of fibers with a diameter of 2 to 8 μm.

(4) Capacitor element structure Winding shape Example 2 (1) Anode foil Same as Example 1.

(2) Chemical oxidative polymerization conditions Same as Example 1.

(3) Electrolytic oxidative polymerization conditions Same as Example 1.

(4) Capacitor element structure The zigzag fold shape shown in FIG. 5 is folded at 10-point intervals.

In Figure 5, 12 is the electrolytic polymer membrane, and the other parts are 3
The same numbers as those in the drawings are given and explanations are omitted.

Conventional example (1) Anode foil Same as Example 1 and Example 2.

(2) Chemical oxidative polymerization conditions Same as Example 1 and Example 2.

(3) Electrolytic oxidation polymerization conditions ・Electrolyte Same as Example 1 and Example 2.

・Power supply electrode Platinum wire with a diameter of 0.8 layers.

As is clear from the above table, Examples 1 and 2 of the present invention, in which carbon paper was used as the power supply electrode in electrolytic oxidative polymerization, are different from the conventional method in which platinum wire was used as the power supply electrode in electrolytic oxidative polymerization. Compared to the example, it not only contributes significantly to the improvement of short circuit defects, but also
It was found that this method is also effective in improving anδ and leakage current characteristics.

Although the above embodiments have been described using aluminum foil as the anode foil, it is also possible to apply these film-forming metal powders to those using film-forming metals such as tantalum foil or niobium foil. Of course, the present invention can be applied to a sintered anode body formed by sintering.

[Effects of the Invention] According to the present invention, since carbon paper is used as a power supply electrode in electrolytic oxidation polymerization, there is no risk of damage to the oxide film or chemically polymerized film of the capacitor element, which greatly contributes to preventing short circuit failures. In addition, it is possible to obtain a method for manufacturing solid electrolytic capacitors that is effective for other special improvements as well.

[Brief explanation of drawings]

Figures 1 to 4 relate to one embodiment of the present invention;
Figures 1 and 2 show an electrolytic cell for electrolytic oxidative polymerization. Figure 1 is a front sectional view, Figure 2 is a side sectional view, and Figure 3 is an exploded perspective view showing a capacitor element before electrolytic oxidative polymerization. Figure, 4th
The figure is a perspective view showing a state in which a plurality of capacitor elements are attached via an aluminum plate before electrolytic oxidation polymerization, and FIG. 5 is a perspective view showing a capacitor element according to another embodiment of the present invention. 2...Chemical polymerization ll13...Anode foil 5...Capacitor element 7...Electrolyte 9...Carbon vapor 10...At the time of electrolytic bath Application Hito Marukon Electronics Co., Ltd. Nippon Carlit Co., Ltd. Capacitor Developed perspective view of the device Fig. 3 Fig. 4 Fig. 12 Perspective view of the capacitor element according to other embodiments of electropolymerized membranes Fig. 5
figure

Claims (1)

[Claims] (1) Forming a dielectric oxide film on the film-forming metal surface,
In a method for manufacturing a solid electrolytic capacitor in which a chemically polymerized film is sequentially formed by chemical oxidation polymerization on this oxide film, and then an electrolytically polymerized film is formed on this chemically polymerized film by electrolytic oxidation polymerization, carbon dioxide is used as a power supply electrode for electrolytic oxidation polymerization. A method for manufacturing a solid electrolytic capacitor characterized by using paper.