JPH077740B2 - Capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention forms an insulating polymer film on a porous conductor surface, and forms a conductive polymer film on this as a dielectric layer. It is related to capacitors that are made.

Conventional technology A film capacitor is usually manufactured by using a polyester film or polypropylene film as a dielectric, winding metal such as aluminum foil on one or both sides, or coating the metal on the film surface by a method such as vacuum deposition. ing.

Generally, in order to obtain a large-capacity film capacitor, a structure in which metallized plastic films are wound or laminated is adopted, but the dielectric constant of plastic films is compared with that of inorganic oxide-based dielectrics. However, it is difficult to obtain a large-capacity film capacitor because there is a limit to how thin the film can be handled, and the limit is several microfarads.

In order to obtain a large capacity, it is advisable to increase the dielectric surface area. For this purpose, it is advisable to make the surface of the conductor serving as an electrode porous and form a dielectric on the surface. But,
Like an etched aluminum foil, an insulating polymer film is formed as a dielectric on the surface of a conductor that has been subjected to a roughening treatment, and even if a metal foil or metal is vapor-deposited to take out the counter electrode, the surface is roughened. Depending on the shape of the conductor, the counter electrode metal layer cannot be formed, and the expected capacity cannot be obtained.

Further, an oxide film is formed as a dielectric on the surface of a valve metal such as aluminum or tantalum, a conductive polymer film layer is formed by chemical polymerization on the oxide film, and a conductive polymer film layer is formed by electrolytic polymerization. A solid electrolytic capacitor having such a structure has been proposed (JP-A-63-158829 and JP-A-63-173313).

With this product, the oxide film of the valve metal used as a dielectric can be made very thin, so it is possible to obtain a small capacitor with a large capacity, but on the other hand, the dielectric oxide film is fragile, so mechanical stress and impact There are many defects such as weakness, and large leakage current. Moreover, since the dielectric oxide film of the valve metal has a rectifying function, only a polar capacitor can be formed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to form a structure in which an insulating polymer film is formed as a dielectric on a porous conductor and a counter electrode is formed on the insulating polymer film. In the capacitor of (3), it is possible to reduce the size and capacity, and to form a counter electrode with good followability according to the shape of the porous conductor.
It is to provide a capacitor having excellent capacitor characteristics.

Means for Solving the Problems In the capacitor of the present invention, a dielectric layer made of an insulating polymer film is formed on a porous conductor, and the surface of the dielectric layer is sequentially increased in conductivity by chemical oxidative polymerization. A molecular film, a conductive polymer film formed by electrolytic polymerization, and a conductive coating film formed on the conductive polymer film formed by electrolytic polymerization.

As the porous conductor, aluminum, tantalum, nickel, titanium, stainless steel, copper, and carbon are preferable because of their ease of porosity, electric conductivity and stability. Further, as a method for making these conductors porous,
Examples include electrochemical etching, chemical etching using acid or alkali, roughening by ion beam or sputtering, roughening by sandblasting or surface polishing, and porosity by sintering fine conductor powder. However, the porous conductor of the present invention is not limited to these examples.

The method for forming the insulating polymer film on the porous conductor is not particularly limited, but examples thereof include polyester, polyvinyl chloride, polystyrene, polyphenylene sulfide, polyphenylene oxide, polyparaphenylene, polyurethane, and acrylic. There is a method in which a resin or the like is dissolved in a good solvent and cast and applied onto a porous conductor, and then the good solvent is removed to form these insulating polymer films on the porous conductor.

Further, there is a method of forming an insulating polyimide thin film on a porous conductor by using a porous conductor surface as a substrate, performing polycondensation on a substrate by simultaneously vacuum-depositing tetracarboxylic acid and diamine. is there.

In addition, acrylic acid and methacrylic acid and their esters,
Vinyl compounds such as styrene, para-xylene dichloride, polyisocyanate, benzene and condensed aromatic polynuclear hydrocarbons, acetylene and its derivatives, heterocyclic compounds, etc., will be on the surface when electrolyzing with a porous conductor as an electrode. A polymer film is formed on.

Further, when a carboxylic acid resin or a solution of an ionic polymer such as a polyamino resin in water or an organic solvent is used as an electrolytic solution and electrolysis is performed using a porous conductor as an electrode, the ionic polymer is Precipitates on the porous metal surface. An insulating polymer film is formed on the surface of the conductor by heating and curing this.

Further, there is a method in which a prepolymer or a monomer alone or in the form of a solution is simultaneously or sequentially coated with a cross-linking agent on the surface of a porous conductor, and then cross-linking is cured to form an insulating polymer film on the surface of the conductor. . At this time, as the prepolymer or monomer, unsaturated polyester, polyurethane prepolymer, polyvinyl alcohol, polyethylene glycol, low molecular weight epoxy resin,
There are polyacrylic acid, polymethacrylic acid, polyamine, polyepihalohydrin and the like, and examples of the cross-linking agent include polyisocyanate, polybasic acid and its chloride, polyamine, bisphenol, melamine and the like.

After forming an insulating polymer film on the surface of a porous conductor using these methods, a solution containing a conductive polymer monomer of at least 0.01 mol / 1 is uniformly formed on the insulating polymer film. After being dispersed, it is chemically polymerized by a method of contacting it with a solution containing 0.001 mol / 1 to 2 mol / 1 of an oxidant, or conversely uniformly dispersing the oxidant and then contacting it with a solution of a conductive polymer monomer. A conductive polymer film I is formed to make the surface conductive. As the conductive polymer, polypyrrole, polythiophene, or polyfuran is used, and from the viewpoint of stability, polypopyr is particularly preferably used.

Oxidizing agents used for chemical polymerization include halogens such as iodine, bromine, and bromine iodide, arsenic pentafluoride, antimony pentafluoride, silicon tetrafluoride, phosphorus pentachloride, phosphorus pentafluoride, aluminum chloride, molybdenum chloride, etc. Metal halides, sulfuric acid, nitric acid, fluorosulfuric acid, trifluoromethane sulfuric acid, chlorosulfuric acid and other protic acids, sulfur trioxide, nitrogen dioxide and other oxygen-containing compounds, sodium persulfate, persulfate such as ammonium persulfate, hydrogen peroxide , Peroxides such as peracetic acid.

After that, when electrolytic polymerization is performed in an electrolytic solution containing a supporting electrolyte of 0.01 mol / 1 to 2 mol / 1 and a conductive polymer monomer of 0.01 mol / 1 to 5 mol / 1, it is uniformly formed on the chemically polymerized conductive polymer film I. An electropolymerized conductive polymer film II is formed.

The supporting electrolyte used in the electropolymerization of the present invention has an anion such as halide anions such as hexafluoroline, hexafluoroarsenic and tetrafluoroboron, halogen anions such as iodine, bromine and chlorine, perchlorate anion, benzenesulfonic acid, It is a sulfonate anion such as alkylbenzene sulfonic acid, and the cation is an alkali metal cation such as lithium, potassium or sodium, or a quaternary ammonium cation such as ammonium or tetraalkylammonium. LiPF ₆ and LiAsF as compounds
₆ , LiClO ₄ , LiBF ₄ , KI, NaPF ₆ , NaClO ₄ , sodium toluenesulfonate, tetrabutylammonium toluenesulfonate and the like.

Then, this element is immersed in colloidal carbon to form a carbon layer on the surface. Further, a conductive coating film is formed thereon with a conductive paste, and a lead wire for leading out an electrode is connected to a part of the conductive coating film. As the conductive paste, silver paste, copper paste, aluminum paste, etc. can be used. The capacitor element configured as described above is completed as a capacitor by a resin mold or an outer case that is sealed in an outer case.

In the capacitor according to the present invention, the insulating polymer film adhered to the surface of the porous conductor is used as the dielectric layer, and the conductive polymer film adhered to the insulating polymer material is used as the counter electrode. Since it works, a small-sized, large-capacity, nonpolar capacitor can be obtained.

Examples Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example-1 An aluminum-etched foil was obtained in which the surface of a high-purity aluminum foil was roughened 100 times by electrolytic etching. The aluminum etched foil was cut into 10 mm × 5 mm and then caulked to attach leads to obtain a roughened metal electrode.

The metal electrode is made of polyethylene terephthalate 5% N, N-
After dipping in a dimethylformamide solution and drying at 100 ° C., an insulating polyethylene terephthalate film having a thickness of 0.1 μm was formed to obtain a device.

This device was immersed in a 2mol / 1 pyrrole / ethanol solution for 5 minutes, and then further immersed in a 0.5mol / 1 ammonium persulfate aqueous solution.
It was immersed for a minute to form a polypyrrole film by chemical polymerization. Further, this device was immersed in an acetonitrile solution containing 1 mol / 1 of pyrrole monomer and 1 mol / 1 of sodium paratoluenesulfonate as a supporting electrolyte, and chemically polymerized polypyrrole was used as an anode, and constant current electrolytic polymerization (1 mA / cm ² , 30 min) was performed to form a polypyrrole film by electrolytic polymerization. This element was dipped in colloidal carbon to form a carbon layer, and then a silver paste was applied to form a conductive coating film, and a cathode was taken out from a part thereof. The device was sealed in a case to complete a capacitor.

The characteristics of this capacitor are shown in Table 1.

Examples 2 to 6 A tantalum sintered body obtained by sintering the aluminum-etched foil in Example 1 to 50 times porous (Example 2), and a sponge nickel having an effective surface area of 30 times (Example 3). ), Titanium sponge having an effective surface area of 50 times (Example 4), spongeless (SUS304) having an effective surface area of 30 times (Example 5), and a thickness of 50 μm roughened 30 times by acid etching.
Example 1 was followed except that the copper foil having a size of 10 mm × 5 mm (Example 6) was used.

The characteristics of the obtained capacitor are shown in Table 1.

Example 7 In Example 1, instead of forming a film of polyethylene terephthalate on the aluminum etch foil, the aluminum etch foil was set as a substrate in a vacuum vapor deposition apparatus, and pyromellitic anhydride and 4,4′-diaminodiphenyl ether were used. Are simultaneously vacuum-deposited independently to form a polyamic acid on the aluminum-etched foil, and then dehydration ring-closing reaction is performed at 200 ° C. to form a polyimide coating having a thickness of 0.6 μm. According to

The characteristics of the obtained capacitor are shown in Table 2.

Example 8 In Example 5, instead of forming a polyethylene terephthalate film on sponge stainless steel, the sponge stainless steel was used as an anode and saturated with phosphorus pentoxide,
0.1 M tetrabutylammonium perchlorate was dissolved in benzene in a solution containing 0.5 M as a supporting electrolyte to carry out electrolytic oxidation to prepare an electrolytic solution, and a thickness of 0.
Same as Example 5 except that an insulating polyparaphenylene film of 3 μm was formed.

The characteristics of the obtained capacitor are shown in Table 2.

Example 9 In Example 5, instead of forming a film of polyethylene terephthalate on sponge stainless steel, the sponge stainless steel was used as an anode and electrodeposition coating was performed in an aqueous solution in which 0.1 M polyacrylic acid was dissolved, followed by 0.5. N
After immersing in KOH aqueous solution, wash with water and bake at 120 ℃,
Example 5 was followed except that a 0.2 μm thick polyacrylic acid film was formed on the sponge stainless steel.

The characteristics of the obtained capacitor are shown in Table 2.

Example 10 In Example 1, instead of forming a film of polyethylene terephthalate on an aluminum-etched foil, the aluminum-etched foil was dipped in a 0.5M methylene chloride solution of sebacoyl chloride for 5 minutes, air-dried, and then hexamethylene. The same procedure as in Example 1 was carried out except that a 6M-nylon film having a thickness of 0.8 μm was formed on the aluminum-etched foil by drying by flood-preventing wire dipped in a 1M aqueous solution of diamine for 20 minutes.

The characteristics of the obtained capacitor are shown in Table 2.

Comparative Example 1 A metallized polyethylene terephthalate film was obtained by vacuum-depositing aluminum to a thickness of about 500Å on both sides of a polyethylene terephthalate film having a thickness of 3 μm. After cutting this film into 10 mm × 5 mm, a lead was taken out using a silver paste on each part of both sides, and then molded with an epoxy resin to obtain a film capacitor. Although this capacitor has a rating of 50 V, it has an electrostatic capacity of 0.000443 μF, and an area of 2000 times or more is required to obtain an electrostatic capacity equivalent to that of the capacitor obtained by the present invention.

Comparative Example 2 The procedure of Example 1 was repeated except that a dielectric oxide film was formed by performing a chemical conversion treatment at 75 V instead of forming the polyethylene terephthalate film on the aluminum-etched foil in Example 1. The obtained capacitor had a rated voltage of 25 V and a capacitance of 7.6 μF (at 120 Hz). On the other hand, the dielectric loss of this capacitor is 0.011 (at 120 Hz) and the insulation resistance is 1250 MΩ, which is superior to the capacitor using a normal liquid electrolyte but inferior to the capacitor of the present invention.

Comparative Example 3 The procedure of Example 1 was repeated except that a gold vapor-deposited film was formed instead of forming a chemically polymerized film or an electrolytically polymerized film of polypyrrole on the polyethylene terephthalate film. The obtained capacitor has a rated voltage of 16V and a capacitance of 0.0.
It was 177 μF (at 120 Hz), and only a small capacitance was obtained as compared with the capacitor obtained in the present invention.

Table 3 shows the characteristics of the capacitors obtained in Comparative Examples 1, 2 and 3.

EFFECTS OF THE INVENTION In the capacitor according to the present invention, since the insulating polymer film thinly formed on the surface of the porous conductor can be effectively used as a dielectric, it has a capacitance comparable to that of a conventional electrolytic capacitor and is nonpolar. It is possible to obtain excellent properties such as low dielectric loss and high insulation resistance.

Front page continued (72) Inventor Nobuyuki Kume 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Inventor Hideo Yamamoto 2470 Handa, Shibukawa City, Gunma Prefecture Central Research Institute, Japan Carlit Co., Ltd. (72) Isao Isa 2470 Handa, Shibukawa City Gunma Prefecture Central Research Center, Japan Carlit Co., Ltd.

Claims (2)

[Claims] 1. A dielectric layer made of an insulating polymer is formed on a porous conductor, and a conductive polymer film formed by chemical oxidation polymerization and a conductive high layer formed by electrolytic polymerization are sequentially formed on the surface of the dielectric layer. A capacitor comprising a molecular film formed and a conductive coating film formed on the conductive polymer film by the electrolytic polymerization. 2. The capacitor according to claim 1, wherein the conductive polymer film is polypyrrole.