JPH01260809A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To make miniaturization and small volume possible by winding an anode foil which forms a conductive high polymer film by a dielectric oxidizing coat and chemical polymerization and a porous conductive paper which forms a conductive high polymer film by chemical polymerization and electrolytic polymerization. CONSTITUTION:A dielectric oxidizing coat 2 is formed on a surface and a conductive high polymer film 3 by chemical polymerization on the dielectric oxidizing coat 2 to be an anode foil 1. Further, the conductive high polymer films 3, 5 by the chemical polymerization and the electrolytic polymerization are formed on a porous paper such as a craft paper and a Manila paper and the porous conductive paper 5 whose surface is made conductive can be obtained. The obtained porous conductive paper 5 is spirally wound together with the anode foil 5 having the dielectric oxidizing coat 2 to make an element.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a solid electrolytic capacitor using a conductive polymer membrane as a solid electrolyte.

(Conventional technology) Solid electrolytic capacitors are usually aluminum.

A dielectric oxide film is formed on the surface of a film-forming metal such as tantalum, and manganese dioxide, TCN, etc. are formed on the oxide film.
It is constructed by sequentially laminating a solid electrolyte layer such as a QS3 body and a conductor layer.

In general, a spirally wound structure is used to achieve large capacity and small size, but as with conventional electrolyte capacitors, a cathode foil is essential, so there is a limit to miniaturization. In addition, capacitors using manganese dioxide as a solid electrolyte have drawbacks such as the dielectric oxide film being easily damaged during the manufacturing process, while capacitors using TCNQ complex have drawbacks such as poor thermal stability. .

Capacitors have been proposed in which a polymer of a heterocyclic compound such as virol is formed by electrolytic polymerization on a dielectric oxide film and used as a solid electrolyte. It was very difficult to form a film, and it was not possible to form a uniform film.

In particular, for elements with a structure in which the anode foil is wound alone,
8 densely in a spiral shape! It is impossible to form a uniform electropolymerized film between i-layered foils. In addition, a conductive polymer film (I) is chemically polymerized using an oxidizing agent on the anodic oxide film, and after winding it together with separator paper and cathode foil to form an element, the conductive polymer film (I) is formed by electrolytic polymerization. A solid electrolytic capacitor with a structure formed by II) has been proposed, but due to the influence of the separator paper, which is an insulator, the formation of a conductive polymer film becomes uneven, resulting in a decrease in capacitance, variations in capacitance, and loss angle. However, there were still some points to be improved, such as a large tangent (tan δ).

(Problems to be Solved by the Invention) It is an object of the present invention to have a structure in which a conductive polymer membrane is used as a solid electrolyte, and to make it possible to reduce the size and volume of the membrane, and to create a uniform conductive polymer membrane. A solid electrolytic capacitor having excellent capacitor characteristics can be provided.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive research, the present inventors came to invent a solid electrolytic capacitor that can achieve the above object.

That is, it consists of an anode foil with a dielectric oxide film formed on its surface, a conductive polymer film (I) produced by chemical polymerization, and a conductive polymer film (It) produced by electrolytic polymerization as an electrolyte, and the surface of porous paper is A conductive polymer film (I) is formed in advance by chemical polymerization to form a porous conductive paper, which is wound with anode foil to form an element, and then a conductive polymer film (II) is formed by electrolytic polymerization. This is a solid electrolytic capacitor using the conductive paper as a cathode.

The present invention will be explained in detail below.

Aluminum, tantalum, niobium, etc. are used as the film-forming metal, and the surface is roughened by electrochemical etching, if necessary. Further, electrolytic oxidation is performed in an aqueous solution of ammonium phosphate, ammonium borate, etc. to form a dielectric oxide film on the surface, thereby obtaining an anode foil. This anode foil is cut to a specified size, and a part of it is caulked.
Connect the lead wire for anode extraction using a method such as ultrasonic welding.

Next, after uniformly dispersing a solution containing at least 0.01 mol/41 of a conductive polymer monomer on the oxide film, it is brought into contact with a solution containing an oxidizing agent o, ooi ~ 2 mo+/, or conversely, the solution is oxidized. After uniformly dispersing the agent, the film is brought into contact with a conductive polymer monomer solution to form a chemically polymerized conductive polymer film (I) to make the surface conductive.

Next, porous kraft paper, Manila hemp paper, a mixed paper thereof, or a mixed paper of these and synthetic HaH having an apparent density in the range of 0.3 to 0.69/cm3 is treated with at least 0% of a conductive polymer monomer. .01 mol/J! After immersion in a solution containing oxidizing agent at 0.001 a+ol
/j)~2 A conductive polymer film (I) chemically polymerized by contacting with a solution containing n+ol/1 or, conversely, by uniformly dispersing an oxidizing agent and then contacting a conductive polymer film Zimmer solution. to make the surface of the porous paper conductive.

Examples of conductive polymers include polypyrrole, polyaniline,
Polythiophene and polyfuran are used, and polypyrrole is particularly preferably used.

The porous conductive paper thus obtained is spirally wound together with an anode foil having a dielectric oxide film to produce an element. After that, the anion is a sulfonic acid anion such as benzenesulfonic acid, alkylbenzenesulfonic acid, or a perchlorate anion.

In addition, a supporting electrolyte whose cations are alkali metal cations such as lithium and potassium, and quaternary ammonium cations such as tetraalkylammonium, 0.01 to 2 m
ol/ρ and conductive polymer monomer 0.01 to 5 mo
In an electrolytic solution containing l/j, constant current electrolysis is performed between the porous conductive paper as an anode and a cathode disposed outside,
A uniform electropolymerized conductive polymer II (II) is formed between the anode foil whose surface has been made conductive and the porous conductive paper.

(Function) In the capacitor element constructed as described above, the porous conductive paper acts as a cathode, and is sealed in a resin mold or case to provide the solid electrolytic capacitor of the present invention.

(Example) Example 1 A dielectric oxide film is formed with a thickness of 40 μm.

An anode lead was attached to a high-purity aluminum foil with a width of 3 mm by ultrasonic welding to obtain an anode foil. 2 mol/of the anode foil
After being immersed in a pyrrole/ethanol solution for 5 minutes, it was further immersed in a 5 mol/41 ammonium persulfate aqueous solution to form a polypyrrole film by chemical polymerization.

Then, the thickness was 35 μm, the apparent density was 0.35 g/ClR3
Tsumanila hemp paper 2 mol/j billow /L/ / After immersed in ethanol solution for 5 minutes, further 0.5nof/
A polypyrrole film was formed on the surface of Manila hemp fiber by chemical polymerization by immersion in Jl ammonium persulfate aqueous solution for 5 minutes to obtain porous conductive paper.

This conductive paper and the anode foil were spirally wound to produce an element, and then the dielectric oxide film was repaired by re-forming.

Furthermore, this element was mixed with 11 ol of virol monomer! and sodium paratoluenesulfonate 1 as a supporting electrolyte.
immersed in an acetonitrile solution containing a+ol/1,
Conductive paper containing chemically polymerized polypyrrole is used as an anode, and a constant DC current is passed between it and the external cathode.
A polypyrrole film was formed by electrolytic polymerization between the 737n paper and the dielectric oxide film on the anode foil whose surface was made conductive.

Thereafter, a cathode lead was connected to the end face of the conductive paper and sealed in a case to complete a solid electrolytic capacitor with a rated voltage of 33 V and a nominal capacitance of 15 μF. This capacitor has approximately two-thirds the volume compared to conventional capacitors that use anode foil, separator paper, and cathode foil, and because a uniform polypyrrole film is formed, variations in capacitance and tan δ can be reduced. I can do it.

Example 2 The paper of Example 1 had a thickness of 4012 m and an apparent density of 0.6 g/c.
The process was carried out in the same manner as in Example 1, except that the paper was changed to kraft paper having a paper size of 1.5 mm.

Example 3 The paper of Example 1 was prepared with a thickness of 50 μm and an apparent density of 0.3 (1/α
Example 1 was carried out in the same manner as in Example 1, except that the paper was changed to a mixed paper of Manila hemp paper (No. 3) and polypropylene i1M.

Example 4 The same procedure as in Example 1 was carried out except that the anode foil was changed to an anode foil whose surface was not made conductive by chemical polymerization.

Reference Example 1 The paper of Example 1 had a thickness of 20 μm and an apparent density of 0.75 g/α.
The process was carried out in the same manner as in Example 1, except that the kraft paper of No. 3 was used.

Reference Example 2 In Example 1, the thickness was 35 μm and the apparent density was 0.35 g.
/cm'' Manila hemp paper was not formed with a polypyrrole film by chemical polymerization, but instead was wound spirally with an anode foil to form an element, and electrolytically polymerized according to Example 1, but polypyrrole was uniformly formed. Therefore, it was not possible to fabricate a solid electrolytic capacitor.

An anode lead was attached and cut to a length of 50 am to obtain an anode foil. The anode foil was immersed in a 2 mol/N pyrrole/ethanol solution for 5 minutes, and then further immersed in a 0.5 mol/j ammonium persulfate aqueous solution for 5 minutes to form a polypyrrole film by chemical polymerization.

Next, this anode foil was made to have a thickness of 35 μm and an apparent density of 0.35.
After creating an element by using Manila hemp paper of g/c 113 as a separator and stacking it with a cathode foil and winding it in a spiral shape, electrolytic polymerization was performed using chemically polymerized polypyrrole as an anode, and a capacitor was manufactured in accordance with the method of Example 1. did. Since this capacitor has a separator paper and a cathode foil, its volume is equivalent to that of a conventional capacitor.

Data of Examples of the present invention are shown in Table 1 together with Reference Examples.

Note that the volume ratios in Table 1 are the volumes of each finished product calculated assuming that the size of a conventional capacitor (Reference Example 3) composed of an anode foil, separator paper, and cathode foil is 100.

Table 1 [Effects of the Invention] A solid electrolytic capacitor using a conductive polymer film as a solid electrolyte includes a dielectric oxide film and an anode foil having a conductive polymer film formed by chemical polymerization on the dielectric oxide film. A solid electrolytic capacitor is a solid electrolytic capacitor in which porous paper is wound with a porous conductive paper in which a conductive polymer film is formed by chemical polymerization and a conductive polymer film is formed by electrolytic polymerization. Compared to wound solid electrolytic capacitors, it has become possible to reduce variations in capacitance and tan δ, and to significantly reduce volume.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of an element structure according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram of an element structure in Example 4. 1... Anode aluminum foil 2... Dielectric oxide film 3... Conductive polymer film by chemical polymerization (I>4...
Porous conductive paper [porous muntin conductive polymer membrane (technique)] 5... Conductive polymer membrane (n) by electrolytic polymerization Patent applicant Marcon Electronics Co., Ltd. Nippon Carlit Co., Ltd.

Claims (3)

[Claims] (1) Anode foil with a dielectric oxide film on the surface and a conductive polymer film formed by chemical polymerization on the dielectric oxide film, and a porous paper with a conductive polymer film formed by chemical polymerization and a conductive film formed by electrolytic polymerization. A solid electrolytic capacitor that is wound with porous conductive paper with a polymer membrane formed on it. (2) The solid electrolytic capacitor according to claim (1), which uses an anode foil having a dielectric oxide film formed on its surface. (3) The solid electrolytic capacitor according to claim (1) or claim (2), wherein the porous paper has a density of 0.3 to 0.69/cm^3.