JPH0629163A - Layered solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain excellent characteristic stabilized over a larger temperature range by fixing a cathode electrode terminal to a cathode layer of a layered body and respectively connecting metal fine leads for anode to the anode electrode terminals fixed to the layered body. CONSTITUTION:A value functioning metal 2, which is harder than a valve functioning metal foil 1, is fastened to the one end of such valve functioning metal foil 1 and metal fine lead 3 for anode, which is softer than the valve functioning metal 2, is fixed to a part of the valve functioning metal 2 projected from the valve functioning metal foil 1. The projected part of the valve functioning metal 2 including the fixing portion is covered with an insulating resin 4, an oxide film 5 of dielectric material is formed as a base material of anode 6 at the surface of the valve functioning metal foil 1, a conductive polymer layer 7-cathode layer 8 are formed on the oxide film 5 of dielectric material to obtain a plate capacitor 9. A plurality of capacitor plates 9 are layered through respective cathode layers 8 and metal fine leads 3 for anode to obtain a laminated material 11. The cathode electrode terminal 12 is connected to the cathode layer 8, while the metal fine lead 3 for anode is connected to the anode electrode terminal 13, and this anode electrode terminal 13 is fixed to an insulating region 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated solid electrolytic capacitor using a conductive polymer as a solid electrolyte.

[0002]

2. Description of the Related Art Conventionally, as a solid electrolytic capacitor, a valve metal such as aluminum, tantalum or niobium is used as an anode body, an oxide film of the valve metal is used as a dielectric, and a solid electrolyte is used as a solid electrolyte on the oxide film. Manganese and 7.
7.8.8. -There is one formed by forming an organic semiconductor or the like composed of a TCNQ complex of tetracyanoquinodimethane.

In recent years, for example, Japanese Patent Laid-Open No. 62-1814.
As disclosed in Japanese Patent Publication No. 15, a five-membered heterocyclic compound such as pyrrole, thiophene, or furan is polymerized by a chemical or electrochemical means to form a conductive polymer such as polypyrrole, polythiophene, or polyfuran. Solid electrolytic capacitors using solid electrolytes have been developed.

This conductive polymer has an electric conductivity of about 10
² S / cm and manganese dioxide (10 ^-2 S / cm),
Since it is extremely higher than TCNQ complex (10 S / cm) and has excellent thermal stability, by using this conductive polymer as a solid electrolyte, impedance frequency characteristics, It is possible to obtain a solid electrolytic capacitor having excellent electrical characteristics such as leakage current characteristics and excellent temperature characteristics in a wide range.

Further, as electronic parts have become lighter, thinner, shorter, and smaller, various methods have been proposed for laminating and integrating anode bodies in a solid electrolytic capacitor for the purpose of increasing the capacity per unit volume. For example, (a) as described in JP-A-61-30020, after connecting an anode lead to a laminated and integrated anode substrate, an oxide film layer, a semiconductor layer, and a conductor layer are sequentially formed. (B) JP-A-63-
As described in Japanese Patent No. 239917, a dielectric oxide film, a semiconductor layer, and a conductor layer are sequentially formed on one of the divided metal substrates by forming an insulating layer on a predetermined portion of a valve action metal plate. There is a method in which a plurality of capacitor base plates are laminated and fixed by a conductive paste, and the exposed portion of the other metal substrate is pressure-integrated and then connected by electric welding to form a laminated body.

[0006]

However, in the above method (a), since the anode substrate has a structure in which single layers are laminated in advance, the semiconductor layer and the conductor layer for each single layer are formed. There is a drawback that the capacitor cannot be formed sufficiently and the basic characteristics of the capacitor are deteriorated as a whole. Further, in the above method (b), after the capacitor base plates are laminated, the exposed portion of the metal substrate is pressure-integrated, so that stress on the portion where the dielectric oxide film, the semiconductor layer, and the conductor layer are formed is prevented. However, there is a defect that defects occur in the dielectric oxide film, the leakage current increases, and a short circuit defect occurs.

The present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to provide excellent electrical characteristics such as frequency characteristics of impedance and leakage current characteristics, and a wide temperature range. It is an object of the present invention to provide a laminated solid electrolytic capacitor having stable characteristics over the range.

[0008]

A laminated solid electrolytic capacitor according to the present invention has a surface which is roughened and a dielectric oxide film is formed on the surface of the valve-acting metal foil. A valve action metal that is harder than this metal foil is fixed, and a fine metal wire for an anode that is softer than this metal is fixed to the protrusion of this valve action metal, and the valve action metal excluding the protrusion and the dielectric of the valve action metal foil. A conductive polymer layer and a cathode layer are sequentially formed on the oxide film to form a capacitor base plate, and the cathode layers of the capacitor base plate correspond to each other, and the thin metal wires for the anode correspond to each other. The cathode layers are joined with a conductive adhesive to form a laminate,
A cathode electrode terminal is fixedly attached to the cathode layer of this laminated body, and each thin metal wire for anode is connected to the anode electrode terminal fixed to the laminated body.

[0009]

According to the laminated solid electrolytic capacitor of the present invention having the above-mentioned constitution, the conductive polymer layer and the conductor layer having a high electric conductivity of 10 ² S / cm and excellent thermal stability are provided. ,
Since it is formed in advance on each capacitor base plate, the conductive polymer layer and the conductor layer can be uniformly formed with a necessary and sufficient thickness. In addition, the thin metal wire for the anode drawn out for leading out the anode is not directly fixed to the valve metal foil, but the valve metal harder than the valve metal foil fixed to the valve metal foil is used. Therefore, the stress applied to the thin metal wire for anode during the manufacturing process is not transmitted to the valve metal foil and is absorbed by the valve metal that is harder than this valve metal foil, and there is a risk of destruction of the dielectric oxide film. Will be resolved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings.

First, as shown in FIG. 3, for example, at one end of a valve-action metal foil 1 having a roughened surface, a surface protruding from the valve-action metal foil 1 and harder than the valve-action metal foil 1 is formed. The roughened valve action metal 2 is fixed by ultrasonic welding, and an anode softer than the valve action metal 2 forming the protrusion is attached to the protrusion of the valve action metal 2 from the valve action metal foil 1. The thin metal wire 3 is fixed, and the entire protruding portion of the valve metal 2 including the fixed portion is covered with an insulating resin 4 such as a polyimide resin. Then, the valve metal foil 1 is suitable for a product rated voltage. By performing a chemical conversion treatment with a voltage, a dielectric oxide film 5 is formed on the surface and an anode substrate 6 is formed.

Next, as shown in FIG.
Is immersed in, for example, a 2M-pyrrole / ethanol solution for 5 minutes, and then further immersed in a 0.5M-ammonium persulfate aqueous solution for 5 minutes to perform chemical oxidative polymerization, and chemical polymerization of polypyrrole is performed on the dielectric oxide film 5. Forming a film,
Then, for example, in an electrolytic polymerization solution containing 0.05 mol / l of alkylnaphthalene sulfonate as a supporting electrolyte and 0.2 mol / l of pyrrole monomer, the chemically polymerized film formed in the previous treatment was used as an anode and an external electrode. Constant current electrolytic oxidation polymerization (1 mA / cm ² , 1 h) is performed between them to form an electrolytic polymerization film made of polypyrrole. That is, by these treatments, a conductive polymer layer 7 composed of a chemically polymerized film and an electrolytic polymerized film is formed on the dielectric oxide film 5 of the anode base 6, and the conductive polymer layer 7 is used for drawing out a cathode. As the graphite layer and the silver paste layer are sequentially formed, the cathode layer 8 is formed and the capacitor base plate 9 is formed.

Therefore, as shown in FIG. 1, a plurality of the capacitor base plates 9 are laminated so that the cathode layers 8 and the anode thin metal wires 3 are laminated in correspondence with each other, and a conductive adhesive 10 is provided between the cathode layers 8. The laminated body 11 is formed by bonding, and after that,
The cathode electrode terminal 12 is connected to the cathode layer 8 part, the metal thin wire 3 for anode is connected to the anode electrode terminal 13, and the anode electrode terminal 13 is fixed to the insulating resin 4 part constituting the laminate 11. After that, as shown in FIG. 4, a resin body 14 is formed by, for example, transfer molding to form a capacitor body 15, and a cathode electrode terminal 12 and an anode electrode terminal 13 led out from the side surface of the capacitor body 15.
The capacitor body 15 along the side surface of the capacitor body 15
The finished product is bent so that it reaches the bottom of the product.

According to the laminated solid electrolytic capacitor of the present embodiment having the above-mentioned structure, the conductive polymer layer 7 and the cathode layer 8 having high electric conductivity and excellent heat resistance are formed in a plurality of layers. Since the process is performed before the capacitor base plate 9 is laminated, the conductive polymer layer 7 and the cathode layer 8 can be uniformly formed on the dielectric oxide film 5 with a necessary and sufficient desired thickness. Therefore, it can contribute to improvement of various electrical characteristics such as impedance frequency characteristics and stabilization of the characteristics in a wide temperature range. Further, the thin metal wire for an anode 3 drawn out for derivation of the anode is not directly fixed to the valve-action metal foil 1, but the valve-action metal foil 2 harder than the valve-action metal foil 1 fixed to the valve-action metal foil 1 is fixed. Because of the interposing structure, the dielectric oxide film 5, the conductive polymer layer 7 and the cathode layer 8 are formed on the valve action metal foil 1, and further the metal thin wire 3 for anode is used during the step of laminating the capacitor base plate 9. The stress applied to the valve action metal foil 1 is not transmitted,
Since the valve action metal 2 harder than the valve action metal foil 1 absorbs it, the dielectric oxide film 5 is not destroyed and the risk of deterioration of the leakage current characteristic is eliminated.

A characteristic comparison between the present invention and the prior art will be described below. (Example A) An aluminum foil having a width of 0.8 mm and a thickness of 0.2 mm was ultrasonically welded to one end of an aluminum foil having a thickness of 3 mm × 3 mm and a thickness of 80 μm over a length of 0.8 mm to bond the aluminum foil. And a 0.1 mmφ silver-plated copper wire for an anode lead is further electro-welded to a 0.2 mm upper portion from the weld end of the aluminum, and the anode base is formed by forming a dielectric oxide film on the surface of the aluminum foil, It was produced by the means described above. (Conventional Example B) A valve action metal foil which is roughened by etching and formed is divided into an anode side and a dielectric / cathode forming side with an insulating resin, and an effective area of the cathode forming side is 3 mm × 3 m.
After stacking four sheets of the anode substrate having m, the anode side and the cathode side corresponding to each other, and collecting the anode side by a method such as caulking or electric welding, the same method as in Example A was applied to the cathode side. A conductive polymer layer made of polypyrrole was formed.

The electrolytic polymerization time was four times as long as that in Example A. After that, a graphite layer and a silver paste layer are sequentially formed on the conductive polymer layer to form a conductor layer and a capacitor element, and subsequently, the capacitor element is made conductive on the cathode side. The anode side was connected to the extraction lead by electric welding on the anode side by an adhesive or soldering, and then the exterior was applied by the same means as in Example A above. (Conventional Example C) After obtaining an anode substrate by the same method as in Conventional Example B, a conductive polymer layer made of polypyrrole is formed on the cathode formation side of this anode substrate by the same method as in Example A, Furthermore, on the conductive polymer layer, a graphite layer and a silver paste layer were sequentially formed to form a conductor layer, and four capacitor base plates were laminated so that the anode side and the cathode side corresponded to each other. In the portion where the silver paste layer for drawing out the cathode is formed, a silver adhesive is further interposed to fix the cathode side,
The capacitor element formed by assembling the anode side by electric welding was subjected to the lead lead connection and the exterior by the same means as in the conventional example B.

The initial characteristics of each of the above-mentioned Example A, Conventional Example B and Conventional Example C were examined, and the following Table 1 is shown.
The results shown in are obtained. In Table 1, the numerical value in the upper row of each column indicates the average value, the numerical value in the lower row in parentheses indicates the distribution range, and ESR is the resistance value at a frequency of 100 kHz. Further, when the frequency-impedance characteristics of each of them were examined, the results shown in FIG. 5 were obtained.

The samples of Example A, Conventional Example B, and Conventional Example C are rated at 10 V-4.7 μF, and the number of each is 100.

[0019]

[Table 1]

As is clear from Table 1 and FIG. 5, in the conventional example B, the characteristics are significantly deteriorated over the entire initial characteristics, and the variations are large. The main reason for this is that since the conductive polymer layer and the conductor layer were formed after the anode substrates were laminated and put together, the formation of these layers was insufficient and uneven adhesion was caused. Is considered to be. Further, in the conventional example C, the leakage current characteristics, the ESR characteristics, and the impedance characteristics are deteriorated. The reason is that the dielectric oxide film is damaged due to the stress when the capacitor base plates are put together, and the leakage current increases. It is considered that this is because at the same time, the cracks were generated in the conductive polymer layer and the conductor layer at the same time, and the resistance value increased in the entire portion.

On the other hand, the one of Example A showed stable characteristics, and demonstrated the excellent effect of the present invention in the chip type laminated solid electrolytic capacitor using the conductive polymer film of this kind as a solid electrolyte. .

The present invention is not limited to the above-mentioned embodiment, and metal other than silver-plated copper wire, such as tin-plated copper wire, nickel wire, and stainless wire, may be used as the metal wire for the anode. Also, as the valve action metal foil and the valve action metal, in addition to aluminum, tantalum, titanium,
Niobium or the like can also be used. Further, in the above embodiment,
By using chip type terminals as the anode lead and the cathode lead and applying the exterior by transfer molding,
Although the chip-type laminated solid electrolytic capacitor has been completed, it is also possible to use a tin-plated CP wire or the like as an electrode terminal and apply a coating by a fluid immersion method or a dip method to make it a lead wire type. Further, the specific joining method of the valve action metal foil and the valve action metal, or the valve action metal and the metal lead wire, the specific method of forming the conductive polymer layer, and the conductor layer are freely selected. It is possible. Further, the present invention is not limited to the above ratings, but can be similarly applied to multilayer solid electrolytic capacitors having various ratings, and similarly excellent effects can be obtained.

[0023]

As described above, in the present invention, the conductive polymer layer and the conductor layer are formed in advance on each capacitor base plate, and when the capacitor base plates are laminated, the cathode layers are electrically conductive. Since it is bonded with an adhesive and the anode lead wire is welded to the valve action metal foil having an effective dielectric oxide film through the anode lead and the valve action metal that is harder than this valve action metal foil. Excellent in electrical characteristics such as impedance frequency characteristics and leakage current characteristics, stable characteristics over a wide temperature range, small size
It is possible to provide a large-capacity laminated solid electrolytic capacitor.

[Brief description of drawings]

FIG. 1 is a perspective view showing a laminated body before packaging according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a capacitor base plate which constitutes one embodiment of FIG.

FIG. 3 is a partial cross-sectional perspective view showing an anode substrate constituting the embodiment of FIG.

FIG. 4 is a perspective view showing a finished product of a laminated solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 5 is a frequency-impedance characteristic curve diagram.

[Explanation of Codes] 1 valve metal foil 2 valve metal 3 thin metal wire for anode 4 insulating resin 5 dielectric oxide film 6 anode substrate 7 conductive polymer layer 8 cathode layer 9 capacitor base plate 10 conductive adhesive 11 Laminated body 12 Cathode electrode terminal 13 Anode electrode terminal 14 Resin exterior 15 Capacitor body

Claims (1)

[Claims] 1. A valve-acting metal having a roughened surface and a dielectric oxide film formed on the valve-acting metal foil, protruding from the metal foil and being harder than the metal foil, is fixed to one end of the valve-acting metal foil. A fine metal wire for an anode, which is softer than this metal, is fixed to the protruding portion of the working metal, and a conductive polymer layer and a cathode layer are sequentially formed on the dielectric oxide film of the valve working metal and the valve working metal foil excluding the protruding portion. A capacitor base plate is formed to form a plurality of layers, and the cathode layers of the capacitor base plate correspond to each other, and the thin metal wires for the anode correspond to each other, and the cathode layers are joined with a conductive adhesive to form a laminate. Is formed, a cathode electrode terminal is fixed to the cathode layer of this laminated body, and each thin metal wire for anode is connected to the anode electrode terminal fixed to the laminated body.