JP2694454B2 - Solid electrolytic capacitors - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor using an organic semiconductor of a heterocyclic compound such as pyrrole, furan and thiophene as an electrolyte, and more particularly to a solid electrolytic capacitor having a small capacity. is there.

[Prior Art] Manganese dioxide (Mn
There are some which use O ₂ ), TCNQ salt, etc. as a solid electrolyte, but the solid electrolytic capacitor using this manganese dioxide (MnO ₂ ) or TCNQ salt etc. as a solid electrolyte has drawbacks in its manufacturing method and the like.
Therefore, the present applicant has developed a new solid electrolytic capacitor using a polymer layer of a heterocyclic compound, which is easy to manufacture and has excellent capacitor characteristics, as a solid electrolyte (see, for example, Japanese Patent Application Laid-Open No. S60-18753)
61-2315, Japanese Patent Laid-Open No. 60-244017, Japanese Patent Application No. 62-
No. 73741).

[Problems to be solved by the invention]

The above-mentioned conventional solid electrolytic capacitor using a polymer layer of a heterocyclic compound as an electrolyte is excellent in various capacitor characteristics such as a small equivalent series resistance (ESR), but there are problems in terms of leakage current and temperature characteristics. Therefore, in order to solve this problem, it is necessary to take measures for various complicated steps.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a solid electrolytic capacitor which does not require any special measures and is particularly excellent in heat resistance as compared with conventional film capacitors.

[Means for solving the problem]

In order to solve the above problems, the present invention has a solid electrolytic capacitor configured as follows.

A polymer thin film layer of a heterocyclic compound is formed on the surface of a conductive metal substrate, the polymer thin film layer of the heterocyclic compound is made into an insulator, and the surface of the polymer thin film layer of the insulated heterocyclic compound is formed. To form a polymer thin film layer of a conductive heterocyclic compound, to form a conductor layer on the surface of the polymer thin film layer of a conductive heterocyclic compound, the conductor layer as one of the electrodes, The metal substrate is used as the other electrode.

In addition, an insulating band layer is formed on a predetermined portion of a conductive metal substrate to divide the surface of the metal substrate into two, and a polymer thin film layer of a heterocyclic compound is formed on one surface of the divided metal substrate. And insulating the polymer thin film layer of the heterocyclic compound to form an insulator, and forming a conductive polymer thin film layer of the heterocyclic compound on the surface of the polymer thin film layer of the insulated heterocyclic compound, A conductive layer is formed on the surface of a polymer thin film layer of a conductive heterocyclic compound, and the conductive layer serves as one electrode and the metal substrate serves as the other electrode.

Further, a dielectric oxide film layer is formed on the surface of the metal substrate or the metal substrate forming the polymer thin film layer of the insulated heterocyclic compound.

[Action]

By configuring the solid electrolytic capacitor as described above, the polymer thin film layer of the heterocyclic compound that has been made into an insulator acts as a dielectric, and the polymer of the heterocyclic compound is around 400 ° C in an oxygen-free atmosphere. Since it is also thermally stable, it becomes a solid electrolytic capacitor having excellent heat resistance as compared with, for example, conventional film capacitors.

Further, since the dielectric is a polymer thin film layer of an insulating heterocyclic compound, it becomes a solid electrolytic capacitor having a small leakage current as described below.

When a conductive polymer thin film of a heterocyclic compound is formed by electrolytic oxidative polymerization on the anodic oxide film of a metal substrate or substrate as in a conventional solid electrolytic capacitor, the lattice defect portion of the anodic oxide film is used. There is a drawback that the co-anodized film is destroyed because it uses the flowing current.
In the present invention, a metal substrate or substrate on which a polymer thin film layer of an insulated heterocyclic compound is formed is immersed in an electrolytic solution, the electrolytic solution is impregnated into the electrolytic solution, and an electric current flowing in the impregnated electrolytic solution is used. To form a polymer thin film layer of a conductive heterocyclic compound, the polymer thin film layer of a conductive heterocyclic compound is not destroyed, without destroying the polymer thin film layer of the insulated heterocyclic compound. Can be formed. Therefore, the solid electrolytic capacitor has a small leakage current. Also, when the conductive polymer thin film layer of a heterocyclic compound is formed by a method other than electrolytic oxidation polymerization, such as vacuum deposition or chemical polymerization, a solid electrolytic capacitor with a small leakage current can be obtained.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the structure of a solid electrolytic capacitor according to the present invention, in which FIG. 1 (a) is a partially cutaway external perspective view, and FIG. 1 (b) is an enlarged sectional view of the cut part. As shown in the figure, the solid electrolytic capacitor has a metal substrate 1 in which a band-shaped insulating strip layer 2 is formed on the entire circumferential surface of a conductive metal substrate 1 at a predetermined position.
Is divided into two parts, one of which is formed with an insulating polymer thin film layer 3 of a heterocyclic compound, and the entire surface of which is formed a conductive polymer thin film layer 4 of a heterocyclic compound. Further, a conductor layer 5 composed of a graphite layer 5-1 and a silver paste layer 5-2 is further formed thereon in this order. Further, the electrode terminal 6 is adhered and fixed to the silver paste layer 5-2 of the conductor layer 5 with a conductive paste such as silver paste, and the electrode terminal 6 is welded to the other metal substrate 1 divided by the insulating strip layer 2. It is attached in.

Hereinafter, the details of each part of the solid electrolytic capacitor having the above structure and the manufacturing method thereof will be described in detail with reference to FIGS. 2 (a) to 2 (d).

The metal substrate 1 may be made of a conductive metal, and is not limited to a metal having a valve action such as aluminum, titanium and tantalum. For example, a conductive metal such as copper may be used. Good.

The insulating strip layer 2 is formed at a predetermined position on the metal substrate 1 (see FIG. 2 (a)), divides the entire surface of the metal substrate 1 into two parts, and further forms an insulating heterocyclic ring. Any material may be used as long as it is formed of a material that does not deteriorate the insulating property in the steps of forming the polymer thin film layer 3 of the formula compound and forming the polymer thin film layer 4 of the conductive heterocyclic compound. Alternatively, it may be formed by applying a strip-shaped coating on the entire circumference of a predetermined position of No. 1 and curing it.

The steps of forming the polymer thin film layer 3 of the heterocyclic compound and the polymer thin film layer 4 of the conductive heterocyclic compound, which are made into an insulating material, are the same as those in the step of forming the polymer thin film layer of the heterocyclic compound, except for the former point of insulation. Both are almost the same. Heterocyclic compounds include pyrrole, furan, thiophene, etc. Here, formation of a thin film layer of a polymer of pyrrole will be described.

One part of the metal substrate 1 divided by the insulating strip layer 2 is immersed in an electrolytic solution containing pyrrole and ammonium borodisalicylate (ABS) of borodisalicylate as a solvent using acetonitrile or acetone as a solvent. By applying a predetermined direct current with 1 as an anode, electrolytic oxidative polymerization occurs in the electrolytic solution, and a polymer thin film layer of pyrrole, that is, a polypyrrole layer is formed on the surface of the metal substrate 1. Since the method for forming this polypyrrole layer is disclosed in detail in Japanese Patent Application Laid-Open No. 62-227647 filed by the applicant of the present invention, its details are omitted here.

Since the polymer thin film layer of pyrrole has conductivity, the polymer thin film layer 3 of pyrrole can be obtained by insulating the polymer thin film layer 3 of heterocyclic compound (see FIG. 2 (b)). Is immersed in a solution containing water, or
Or by leaving it in a high temperature tank containing oxygen (180 ℃ ~ 350 ℃), oxygen in water or oxygen in oxygen atmosphere,
The polymer thin film layer reacts and the polymer thin film layer is completely insulated.

This polymer thin film layer 3 of an insulated heterocyclic compound
A polymer thin film layer 4 of a heterocyclic compound having conductivity is formed thereon by the same method as described above (see FIG. 2 (c)).
Here, the polymer thin film layer 3 of an insulated heterocyclic compound is not a perfect film-like film that does not allow water to permeate, but a thin film in the form of aggregated particles. When the metal substrate 1 is immersed in an acetonitrile electrolyte solution containing pyrrole and ammonium borodisalicylate (ABS) in order to form the conductive polymer thin film layer 4 of the heterocyclic compound on the polymer thin film layer 3 of the compound,
The electrolyte solution is impregnated through the gaps between the particles of the polymer thin film layer 3 of the insulated heterocyclic compound. Therefore,
By applying a voltage between both electrodes using the metal substrate 1 as one electrode and the electrolytic solution as the other electrode, a current partially flows through the impregnated electrolytic solution. By utilizing the place where the current flows, the conductive polymer thin film layer 4 of the heterocyclic compound can be formed on the polymerized thin film layer 3 of the heterocyclic compound.

The polymer thin film layer of the heterocyclic compound is not limited to the one formed by electrolytic oxidation polymerization as described above, and may be formed by a vacuum vapor deposition method, a chemical polymerization method or the like.

Next, the graphite layer 5-1 is applied on the polymer thin film layer 4 of the conductive heterocyclic compound and cured, and then the silver paste layer 5-2 is applied and cured to form the conductor layer 5. {See FIG. 2 (d)}.

By configuring the solid electrolytic capacitor as described above, the polymer thin film layer 3 of the insulating heterocyclic compound corresponds to the film of the film capacitor. Moreover, since the polymer of the heterocyclic compound is thermally stable in an oxygen atmosphere up to around 400 ° C., it has excellent heat resistance as compared with a film capacitor using a resin film. Further, since the polymer thin film layer 3 of the heterocyclic compound is completely insulated, it becomes a capacitor having an extremely small leakage current.

Although a conductive metal plate is used for the metal substrate 1 in the above-mentioned embodiment, it is not limited to a plate shape, and the insulating strip layer 2 divides the entire surface of the metal substrate 1 into two. It is convenient for forming an insulating polymer thin film layer 3 of a heterocyclic compound, a conductive polymer thin film layer 4 of a heterocyclic compound, or the like on one side, and in the solid electrolytic capacitor of the present invention, It is not absolutely necessary.

Further, as the metal substrate 1, for example, a metal having a valve action such as aluminum, titanium and tantalum capable of forming a dielectric oxide film on the surface is used, and a dielectric oxide film is formed on the surface of the metal substrate 1 and insulation is performed thereon. The withstand voltage was further improved by forming the polymerized thin film layer 3 of the heterocyclic compound and using this dielectric oxide film layer and the polymerized thin film layer 3 of the heterocyclic compound as the dielectric. It can be a solid electrolytic capacitor.

〔The invention's effect〕

As described above, according to the present invention, the following excellent effects can be obtained.

The insulating polymer thin film of heterocyclic compound acts as a dielectric, and the polymer of heterocyclic compound is thermally stable up to around 400 ° C in an oxygen-free atmosphere. The resulting solid electrolytic capacitor has excellent heat resistance compared to conventional film capacitors.

A dielectric oxide film layer is formed on the surface of a metal substrate or a metal substrate, and a polymer thin film layer of an insulated heterocyclic compound is formed on the dielectric oxide film layer, which is used as the dielectric of the capacitor. It becomes a solid electrolytic capacitor.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of a solid electrolytic capacitor according to the present invention. FIG. 1 (a) is a partially cut external perspective view, FIG. 1 (b) is an enlarged sectional view of the cut part, and FIG. 2 (a). 8A to 8D are views showing the manufacturing process of the solid electrolytic capacitor. In the figure, 1 ... Metal substrate, 2 ... Insulating band layer, 3 ... Insulated polymer thin film of heterocyclic compound, 4 ... Conductive heterocyclic compound thin film layer, 5 ... … Conductor layer, 6,7 …… Electrode terminals.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiya Takahashi 260 Kitamikata, Takatsu-ku, Kawasaki-shi, Kanagawa Nittsu Kogyo Co., Ltd.

Claims (3)

(57) [Claims] 1. A polymer thin film layer of a heterocyclic compound is formed on the surface of a conductive metal substrate, the polymer thin film layer of the heterocyclic compound is made into an insulator, and the heterocyclic compound of the insulator is made of A polymer thin film layer of a conductive heterocyclic compound is formed on the surface of the polymer thin film layer, a conductor layer is formed on the surface of the polymer thin film layer of the conductive heterocyclic compound, and the conductor layer is A solid electrolytic capacitor comprising an electrode and the metal substrate as the other electrode. 2. A polymer of a heterocyclic compound is formed by forming an insulating band layer on a predetermined portion of a conductive metal substrate to divide the surface of the metal substrate into two, and one surface of the divided metal substrate. Forming a thin film layer, insulating the polymer thin film layer of the heterocyclic compound, and forming a conductive polymer thin film layer of the heterocyclic compound on the surface of the polymer thin film layer of the insulated heterocyclic compound Then, a conductor layer is formed on the surface of the polymer thin film layer of the conductive heterocyclic compound, and the conductor layer serves as one electrode and the metal substrate serves as the other electrode. Solid electrolytic capacitor. 3. A dielectric oxide film layer is formed on the surface of a metal substrate or a metal substrate forming the polymer thin film layer of the insulated heterocyclic compound. ) Or the solid electrolytic capacitor as described in (2).