JPH06314641A - Method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] (Correction) [Constitution] A grid-shaped pattern in which a solid electrolyte and a cathode layer are sequentially formed on the surface of a long valve action metal foil on which a dielectric oxide film is formed is predetermined. Are formed at intervals, and then a plurality of the elongated valve action metal foils are laminated so that the patterns overlap each other, and after bonding to a lead frame provided with anode leads and cathode leads at predetermined intervals, A method for manufacturing a solid electrolytic capacitor, characterized by separating each pattern and commercializing it. [Effect] A small-sized and large-capacity laminated solid electrolytic capacitor that does not impair the capacitor characteristics can be obtained in a simple process with good mass productivity. Also, the dimensional accuracy is good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor.

[0002]

2. Description of the Related Art A solid electrolytic capacitor has been proposed in which a dielectric oxide film is formed on the surface of a valve metal and a conductive polymer film is formed on the dielectric oxide film to form a solid electrolyte.

In Japanese Patent Laid-Open No. 63-173313, a conductive polymer film formed by chemical polymerization is used as a conductive precoat layer on a dielectric oxide film in order to apply a conductive polymer film formed by electrolytic polymerization as a solid electrolyte. There is disclosed a solid electrolytic capacitor in which a conductive polymer film is formed by electrolytic polymerization on the conductive polymer film to form a solid electrolyte. Further, in Japanese Patent Laid-Open No. 63-158829, a thin film of a conductive metal oxide such as manganese dioxide is formed as a conductive precoat layer on a dielectric oxide film, and then a high conductivity by electrolytic polymerization is formed on the thin film. A solid electrolytic capacitor in which a molecular film is formed into a solid electrolyte is disclosed. These capacitors are
Excellent frequency characteristics, electrical characteristics and heat resistance.

In the method of manufacturing a solid electrolytic capacitor,
In order to take advantage of the small size and large capacity that aluminum electrolytic capacitors originally have, there is known a method of winding or laminating aluminum foil to obtain a large area, but the manufacturing process is complicated and the There were drawbacks such as damage to the body oxide film.

As a method for manufacturing a small-sized and large-capacity solid electrolytic capacitor element with good mass productivity, a large number of grid-shaped patterns are formed on the surface of an aluminum foil, and a solid electrolyte is formed in the grids. A method has been proposed in which a large number of capacitor elements are formed at one time by cutting. However, in general, in an electrolytic capacitor made of aluminum or tantalum, in order to improve heat resistance and moisture resistance, a capacitor element is bonded to a lead frame having an anode lead and a cathode lead, and then molded with an epoxy resin or the like to form an exterior. It is applied and the capacitor is obtained.

In order to mold a capacitor element in which a large number of grid-like patterns are formed on the surface of an aluminum foil and the grid is cut into a large number of pieces at a time, the anode part and the cathode part of the separated elements are molded. A step of molding with an epoxy resin is required after bonding to the anode lead portion and the cathode lead portion of the lead frame, respectively. This operation is complicated because each element is handled one by one, and in particular, when the elements are stacked and mounted on the lead frame, there is a problem in terms of dimensional accuracy.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to form a solid oxide by forming a dielectric oxide film on the surface of a valve metal and forming a conductive polymer film on the dielectric oxide film to form a solid electrolyte. To provide a method for manufacturing a small-sized and large-capacity solid electrolytic capacitor that does not impair the capacitor characteristics, and a method for manufacturing a laminated solid electrolytic capacitor with good productivity in a simple process. Is.

[0008]

As a result of intensive studies, the present inventors have completed a method of manufacturing a solid electrolytic capacitor capable of solving the above problems.

That is, according to the present invention, a grid-like pattern in which a solid electrolyte and a cathode layer are sequentially formed at predetermined intervals is formed on the surface of a long valve action metal foil on which a dielectric oxide film is formed. Then, a plurality of the elongated valve action metal foils are laminated so that the patterns are overlapped with each other, and after bonding to a lead frame provided with an anode lead and a cathode lead at predetermined intervals, they are separated for each pattern. The method for producing a solid electrolytic capacitor is characterized by commercialization.

The method of manufacturing the solid electrolytic capacitor of the present invention will be described below with reference to the accompanying drawings.

Aluminum, tantalum, titanium, or an alloy thereof is used as the valve metal, and is used in the form of foil or plate.

Next, the case where aluminum foil is used as the valve metal will be described.

After etching the surface of the large area aluminum foil 1, anodization is performed in an aqueous solution of ammonium adipate or the like to form a dielectric oxide film on the surface.
As shown in FIG. 1, an insulating coating film 5 was formed on both surfaces of an aluminum foil 1 on which a dielectric oxide film 2 was formed, leaving a pattern of a pair of an anode extraction portion 3 and a solid electrolyte forming portion 4. Let it form. The space between the patterns is constant according to the space between the leads of the lead frame.

Next, a solid electrolyte and a cathode layer are sequentially formed on the pattern.

The solid electrolyte is formed by first forming a conductive precoat layer in the pattern and then forming a conductive polypyrrole film by electrolytic polymerization.

The method of forming the conductive precoat layer includes:
Method of forming conductive polymer film by chemical oxidative polymerization of conductive polymer monomer, method of forming thin film of conductive metal oxide such as conductive manganese dioxide by thermal decomposition of manganese salt, solvent soluble conductivity such as polyaniline There is a method of impregnating with an organic polymer or a tetracyanoquinodimethane complex solution and drying.

Particularly preferred is a method of forming a conductive polypyrrole film by chemical oxidative polymerization by dropping a predetermined amount of a pyrrole monomer solution and an oxidant solution onto the dielectric oxide film exposed in the pattern.

After that, an electrode is brought into contact with the conductive precoat layer from the outside or a conductive coating film formed in the vicinity by a printing method is used as an anode for electrolytic polymerization, and a supporting electrolyte of 0.01 to
Electropolymerization is performed in an electrolytic solution containing 2 mol / l and 0.01 to 5 mol / l of pyrrole monomer to form a polypyrrole film by electrolytic polymerization.

Then, a cathode layer is formed on the surface of the conductive polypyrrole film by electrolytic polymerization with carbon paste and silver paste.

Although the treatment of only one side of the aluminum foil has been described above, the same treatment is performed on the back side to form the conductive polypyrrole film on both sides.

As the insulating coating film at the time of pattern formation, a heat-resistant polymer such as epoxy resin, phenol resin, polyimide resin, polyester resin, polyphenylene sulfide resin, silicon resin, fluororesin, or a mixture or copolymer thereof is used. Materials are given.

The pattern can be formed by a printing method such as a roll coater, a reverse coater, or screen printing, which can form a large number of square-shaped patterns at a time, which is good for mass production.

Instead of the above steps, a foil similar to that shown in FIG. 1 can be obtained even if a large-area aluminum foil is preliminarily patterned with an insulating coating film and then etched and formed. it can.

Next, it is cut into a long shape along the grid pattern. At the position shown in FIG. 1, the insulating coating film 5 is cut using a mechanical means such as a cutter or a thermal means such as a YAG laser, leaving the anode extraction portion 3 and the portion 4 for forming a solid electrolyte. When a laser is used, physical damage is less likely to occur, so that characteristics such as a small leakage current are stable.

A plurality of the obtained long elements are laminated so that the respective patterns are overlapped, and the cathode layers are connected to each other by the cathode lead 8
It is bonded to the cathode 10 of the lead frame with silver paste or the like. The anode lead-out portion 3 is directly or connected to the anode lead 9
To the anode 11 of the lead frame by means of electrical or thermal means. FIG. 2 is a schematic diagram in which the elements are laminated on the lead frame and joined. FIG. 3 is a cross-sectional view in which elements are stacked and joined to a lead frame.

In this step, instead of laminating the long elements in advance and then joining them to the lead frame, they may be joined while being laminated to the lead frame.

Next, leaving the respective grid-like patterns, the insulating coating films are separated one by one in the vertical direction at the positions shown in FIG. The cutting is performed using a mechanical means such as a cutter or a thermal means such as a YAG laser. In order to prevent mechanical damage to the device, it is preferable to use a dicer equipped with a diamond cutter.

Thereafter, a resin mold or the like is applied to each element to obtain a capacitor.

[0029]

EXAMPLES Examples of the present invention will be described below. The present invention is not limited to the examples.

Aluminum foil with an etched surface (50
mm × 50 mm) was subjected to chemical conversion treatment in an aqueous solution of ammonium adipate at 40 V to form a dielectric oxide film. Screen printing using epoxy resin as an insulating coating film, as shown in FIG. 1, separated into two parts, anode extraction part 3 (3 mm x 1 mm) and solid electrolyte forming part 4 (3 mm x 5 mm). Then, a square-shaped pattern (4 vertical rows × 8 horizontal rows) was formed. Subsequently, a silicone resin was screen-printed on this to leave a grid pattern of 3 mm × 1 mm and 3 mm × 6 mm (4 vertical rows × 8 horizontal rows) to form an insulating coating film.
A similar insulating coating film was formed on the back surface.

In this pattern, using an 8-channel multi-channel micropipette (manufactured by SOCOREX), 5 μl of an ethanol solution containing 30% by weight of a pyrrole monomer was used.
l Drop and let stand for 1 minute, then use 0.1 channel ammonium persulfate with an 8-channel multi-channel micropipette.
10 μl of a 1 / l aqueous solution was added dropwise. Then, after leaving for 5 minutes, it was washed with water and dried to form a polypyrrole film by chemical polymerization. The back side was treated similarly.

Thereafter, this foil was anodized in an aqueous solution of ammonium adipate at 36 V to chemically reform the dielectric oxide film.

Next, a stainless steel electrode was brought into contact with the polypyrrole film formed by chemical polymerization in each square from the outside, and 0.4 mol / l of pyrrole monomer, 0.4 mol / l of 1,7-naphthalenesulfonic acid tetraethylammonium salt and acetonitrile were added. It was immersed in a stainless steel container containing the electrolytic solution. Constant current electrolytic polymerization (0.5 mA / pin, 90 minutes) was performed between the stainless steel container and the external electrode as an anode to form a polypyrrole film by electrolytic polymerization. After removing the external electrodes,
Colloidal carbon and silver paste were applied on the polypyrrole film to form a cathode layer.

Subsequently, at the position shown in FIG. 1, leaving the anode lead-out portion 3 and the portion 4 for forming the solid electrolyte, the insulating coating film 5 is cut on the insulating coating film 5 with a cutter so as to be elongated along a grid pattern. It was cut into strips to obtain four long foils. Two pieces of this foil were laminated, and the cathode layers were bonded to the cathode 10 of the lead frame with the silver paste through the cathode leads 8.
The anode lead-out portion was welded to the anode 11 of the lead frame via the anode lead 9 with a spot welding machine.

Next, a diamond cutter (outer diameter: 54 m
Using an automatic cutting saw DAC-2SP manufactured by Disco Co., which is provided with m), only the element portion was cut in the vertical direction while being careful not to cut the lead frame.

After cutting, this element was molded with epoxy resin to obtain 16 capacitors having a rated voltage of 16 V and a rated electrostatic capacity of 22 μF.

The average value of the initial characteristics of the capacitor is 120 Hz
At a capacitance of 22.7 μF and a loss angle tangent at 120 Hz (ta
nδ) is 0.90% and the equivalent series resistance (ESR) at 100 kHz is
The leakage current at 30 mΩ and 16 V was 0.01 μA or less.

[0038]

According to the method for producing a solid electrolytic capacitor of the present invention, a small-sized and large-capacity solid electrolytic capacitor can be produced by a combination of simple steps. In particular, in producing a large-capacity capacitor by lamination, one element is used. The complexity of stacking them one by one is eliminated, and the dimensional accuracy during stacking is good.

[Brief description of drawings]

FIG. 1 is a plan view in which a pattern is formed on an aluminum foil with an insulating coating film.

FIG. 2 is a schematic view in which an element is laminated on a lead frame and joined.

FIG. 3 is a cross-sectional view in which elements are stacked and joined to a lead frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum foil 2 Dielectric oxide film 3 Anode extraction part 4 Part for forming a solid electrolyte 5 Insulating coating film 6 Solid electrolyte 7 Cathode layer 8 Cathode lead 9 Anode lead 10 Lead frame cathode 11 Lead frame anode

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01G 9/05 F 9174-5E

Claims (3)

[Claims] 1. A grid-shaped pattern, in which a solid electrolyte and a cathode layer are sequentially formed, is formed at a predetermined interval on a surface of a long valve action metal foil having a dielectric oxide film formed thereon, and then, A plurality of the elongated valve action metal foils are laminated so that the patterns overlap with each other, and after joining to a lead frame provided with an anode lead and a cathode lead at predetermined intervals, they are separated for each pattern to be commercialized. A method of manufacturing a solid electrolytic capacitor, comprising: 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the grid-like pattern is separated into an anode lead-out portion and a portion for forming a solid electrolyte. 3. The method for producing a solid electrolytic capacitor according to claim 1, wherein the solid electrolyte comprises a conductive polypyrrole film formed by chemical oxidative polymerization and a conductive polypyrrole film formed by electrolytic polymerization.