JPH09266140A - Method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

(57) An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor, which can surely bond the other cathode of a capacitor element to a cathode lead terminal in a simple process and is excellent in mass productivity. A capacitor element sheet is obtained by forming a dielectric oxide film on both surfaces of a valve metal and then forming a solid electrolyte layer and a cathode layer in a grid pattern to cut a capacitor element sheet to obtain a capacitor element. Next, one of the cathodes of the capacitor element is joined to the cathode lead terminal. After the insulating resin is applied to the cut surface of the capacitor element on the cathode lead side, the other cathode of the capacitor element and the cathode lead terminal are joined with silver paste. Further, the anode of the capacitor element and the anode lead terminal are joined together, and finally the capacitor element is covered with a mold resin to manufacture a solid electrolytic capacitor.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a solid electrolytic capacitor. In particular, it relates to a method for joining a cathode of a capacitor element and a cathode lead terminal.

[0002]

2. Description of the Related Art Conventionally, a dielectric oxide film is formed on the surface of a valve metal foil, and a large number of square-shaped patterns of a predetermined size are formed on the dielectric oxide film by an insulating coating. A method has been proposed in which a conductive polymer film layer and a cathode layer are sequentially formed on a square to form a solid electrolyte layer, which is then cut into patterns and connected to lead terminals to form a solid electrolytic capacitor. For example, Japanese Unexamined Patent Publication (Kokai) No. 6-34639 discloses that after forming a cathode layer, each pattern is cut with a cutter or the like, and then the cathode of the capacitor element and the cathode lead terminal are joined with a lead wire.

However, in the case of joining the cathode and the cathode lead terminal of the capacitor element with the lead wire, one of the lead wires is joined with silver paste and the other of the lead wires is spot-welded, so that the process becomes complicated. There was a point. Further, in spot welding, there are problems such as a high defective welding rate because the lead wire has a small diameter.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems, provide a simple process for surely joining the cathode of the capacitor element and the cathode lead terminal, and have good mass productivity. An object of the present invention is to provide a method for manufacturing an electrolytic capacitor.

[0005]

As a result of intensive studies, the present inventors have found a method of manufacturing a solid electrolytic capacitor which can solve the above problems, and have completed the present invention.

That is, according to the present invention, a step of forming a capacitor element sheet by forming a dielectric oxide film on both surfaces of a valve metal and then forming a solid electrolyte layer and a cathode layer in a grid pattern to form a capacitor element sheet. A step of cutting the sheet to obtain a capacitor element, a step of joining one of the cathode of the capacitor element and a cathode lead terminal, a step of applying an insulating resin to the cut surface of the capacitor element on the cathode lead side, A method for manufacturing a solid electrolytic capacitor including a step of joining the other and a cathode lead terminal, a step of joining an anode of a capacitor element and an anode lead terminal, and a step of coating the capacitor element with a mold resin. .

Hereinafter, the present invention will be described with reference to the drawings.
This will be described in detail.

The steps of forming a dielectric oxide film on both sides of a valve metal and then forming a solid electrolyte layer and a cathode layer in a grid pattern to produce a capacitor element sheet are as follows.

The valve metal used in the present invention includes
Examples include foil-shaped or plate-shaped aluminum, tantalum, titanium, or an alloy thereof.
Further, a case where a polypyrrole film is used as the solid electrolyte layer will be described as an example.

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 2, and then, as shown in FIG. 1, the dielectric oxide film is formed. 2 is left on both surfaces of the aluminum foil 1 on which the solid electrolyte layer is to be formed, and the anode leading portion 4 is left with the first grid-like pattern.
The first insulating coating film 5 is formed. Then, on the first insulating coating film 5, a conductive coating film 6 to be a power feeding electrode during electrolytic polymerization.
Is formed. At this time, the conductive coating film 6 is formed so as not to contact the dielectric oxide film 2 exposed in the first pattern.

Then, as shown in FIG. 2, a second insulating coating film 7 is formed, leaving the second pattern in a grid pattern of the portion where the solid electrolyte layer is formed and the anode leading portion 4. The dielectric oxide film 2, a part 8 of the first insulating coating film 5 and a part 9 of the conductive coating film 6 are exposed in the second pattern. A coating film is similarly formed on the back surface. FIG. 3 is a sectional view taken along the line ab of FIG.

Examples of the first insulating coating film include epoxy resin, phenol resin, polyimide resin, polyester resin, polyphenylene sulfide resin, a mixture thereof, a copolymer and the like. Examples of the second insulating coating film include silicone resin, fluororesin, a mixture thereof, a copolymer and the like. Examples of the conductive coating film include silver paste, carbon paste, nickel paste and the like.

The pattern can be formed by a printing method such as a roll coater, a reverse coater, or screen printing, so that a large number of patterns can be formed at one time and mass productivity is good.

Next, as shown in FIG. 4, on the dielectric oxide film 2 exposed in the second pattern, the part 8 of the first insulating coating film and the part 9 of the conductive coating film, A predetermined amount of each of the pyrrole monomer solution and the oxidant solution is dropped to form the chemically polymerized polypyrrole film 10. At this time, the chemically polymerized polypyrrole film is not formed on the anode lead-out portion 4 exposed in the first pattern.

Next, the damaged portion of the dielectric oxide film formed by the time of forming the chemically polymerized polypyrrole film is chemically repaired. In the chemical conversion repair, the aluminum foil on which the chemically polymerized polypyrrole film is formed is immersed in a chemical conversion liquid such as ammonium adipate to perform anodization.

Thereafter, a part of the end of the conductive coating film 6 is used as an anode, and the supporting electrolyte is 0.01 to 2 mol / l and the pyrrole monomer.
Electrolytic polymerization is performed in an electrolytic solution containing 0.01 to 5 mol / l to form an electrolytically polymerized polypyrrole film 11 on the chemically polymerized polypyrrole film 10.

Examples of the anion of the supporting electrolyte include halide ions such as hexafluoroline, hexafluoroarsenic, hexafluoroantimony, tetrafluoroboron and perchloric acid, halogen ions such as iodine, bromine and chlorine, methanesulfonic acid and dodecylsulfone. Alkylsulfonic acid ion such as acid, benzenesulfonic acid, paratoluenesulfonic acid, dodecylbenzenesulfonic acid, alkyl-substituted or unsubstituted benzene mono- or disulfonic acid ion such as benzenedisulfonic acid, 2-naphthalenesulfonic acid,
1,7-naphthalenedisulfonic acid and other sulfonic acid groups 1
~ Alkyl-substituted or unsubstituted ion of 4 substituted naphthalene sulfonic acid, alkyl biphenyl sulfonic acid,
Alkyl-substituted or unsubstituted biphenyl sulfonic acid ion such as biphenyl disulfonic acid, polystyrene sulfonic acid, high molecular weight sulfonic acid ion such as naphthalene sulfonic acid formalin condensate, bissaltylate boron, boron compound ion such as biscatecholate boron, PMo ₁₂ O
Heteropoly acid ions such as ₄₀ can be mentioned, and preferably sulfonate ion can be mentioned.

The cation is an alkali metal ion such as lithium, potassium or sodium, or a quaternary ammonium ion such as ammonium or tetraalkylammonium. The compounds include LiPF ₆ , LiAsF ₆ ,
LiBF ₄ , KI, NaPF ₆ , NaClO ₄ , sodium toluenesulfonate, tetrabutylammonium toluenesulfonate, sodium 1,7-naphthalenedisulfonate, n
Examples include tetraethylammonium octadecylnaphthalene sulfonate and tetramethylammonium bissalicylate boron.

After that, a cathode layer 12 is formed on the surface of the electropolymerized polypyrrole film 11 with a carbon paste and a silver paste. The back surface of the aluminum foil is also subjected to the same treatment to form a solid electrolyte layer and a cathode layer on both sides in a grid pattern to prepare a capacitor element sheet.

The process of cutting the capacitor element sheet to obtain the capacitor element is as follows.

The produced capacitor element sheet is cut at the cutting points shown in FIGS. 2 and 4 using a cutter or the like.

Fixing the capacitor element sheet with an adhesive tape or a heat release tape prior to cutting prevents scattering of the capacitor element and improves workability in a later step of mounting the capacitor element on a lead terminal. It is possible and preferable.

The step of joining one of the cathodes of the capacitor element to the cathode lead terminal, the step of applying an insulating resin to the cut surface of the capacitor element on the cathode lead side, and the step of joining the other cathode of the capacitor element to the cathode lead terminal. The steps to be performed are as follows.

As shown in FIG. 5, the back surface of the cathode layer 12 of the capacitor element and the cathode lead terminal 13 are bonded with the silver paste 15. Next, the insulating resin 14 is applied to the cut surface on the cathode lead side of the capacitor element, and the aluminum portion which becomes the anode and is exposed on the cut surface is masked. Then, the surface of the cathode layer 12 of the capacitor element and the cathode lead terminal 13 are bonded onto the insulating resin 14, the cathode layer 12, and the cathode lead terminal 13 by the conductive resin 15.

The insulating resin used in the present invention includes:
Examples thereof include epoxy resin, phenol resin, polyimide resin, polyester resin, polyphenylene sulfide resin, mixtures thereof, and copolymers.

As the conductive resin used in the present invention,
Examples thereof include silver paste, copper paste, nickel paste and the like.

The steps of joining the anode of the capacitor element and the anode lead terminal and the step of coating the capacitor element with the mold resin are as follows.

The spot welding machine 17 is used to join the anode part 16 of the capacitor element and the anode lead terminal 17. Further, it is molded with epoxy resin to produce a capacitor having a rated voltage of 16 V and a rated electrostatic capacity of 10 μF.

According to the present invention, the cathode of the capacitor element and the cathode lead terminal can be securely bonded, and the solid electrolytic capacitor can be manufactured in a simple process and with excellent mass productivity.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on examples with reference to the drawings. In reality, 500 capacitor elements were taken per capacitor element sheet, but in the embodiment, 16 capacitor elements are taken.

Example Aluminum foil 1 having a surface etched (length 30 mm × width 50)
mm) was subjected to chemical conversion treatment in an aqueous solution of ammonium adipate at 40 V to form a dielectric oxide film 2.

As shown in FIG. 1, a first grid-shaped portion is divided into two parts 3 (length 5 mm × width 3 mm) for forming a solid electrolyte layer and an anode lead portion 4 (length 1 mm × width 3 mm). After the pattern (2 vertical rows x 8 horizontal rows) is left, the epoxy resin is screen-printed to form the first insulating coating film 5,
A nickel paste was screen-printed on the first insulating coating film 5 in the shape of a fish bone to form a conductive coating film 6.

Subsequently, as shown in FIG. 2, a silicon resin is screen-printed, leaving a first grid-like pattern of the portion 3 on which the solid electrolyte layer is to be formed and the anode lead-out portion 4, and a second resin is formed. The insulating coating film 7 was formed. In the second pattern formed by the second insulating coating film 7, the dielectric oxide film 2, a portion 8 of the first insulating coating film 5 and the conductive coating film 6 are formed.
A part 9 of is exposed. A coating film was similarly formed on the back surface.

In the second pattern, the pyrrole monomer 30
5 μl of wt% ethanol solution was dropped using a dispenser, left for 1 minute, then 10 μl of 0.1 mol / l ammonium persulfate aqueous solution was dropped using a dispenser, left for 5 minutes, washed with water and dried, As shown in FIG. 4, a chemically polymerized polypyrrole film 10 was formed. The back side was treated similarly. After that, anodization was performed at 40 V in an aqueous solution of ammonium adipate to chemically reform the dielectric oxide film.

Then, a part of the end of the conductive coating film 6 was connected to a power source, and pyrrole monomer 0.4 mol / l and 1,7-naphthalenesulfonic acid tetraethylammonium 0.4 mol / l.
And was immersed in a stainless steel container containing an electrolytic solution of acetonitrile. Using the conductive coating film 6 as an anode, constant current electrolytic polymerization (0.3 mA / pin, 30 minutes) was performed between it and the stainless steel container,
As shown in FIG. 4, an electrolytic polymerization polypyrrole film 11 was formed. A carbon paste and a silver paste were applied on the polypyrrole film to form the cathode layer 12, and a capacitor element sheet was produced. Then, the capacitor element sheet was fixed on an adhesive tape, and the capacitor element sheet was cut at a cutting position shown in FIGS. 2 and 4 using a guillotine cutter (manufactured by Sankyo Co., Ltd.) to obtain a capacitor element.

Next, as shown in FIG. 5, the obtained capacitor element was placed on the lead terminal, and the back surface of the cathode layer 12 of the capacitor element and the cathode lead terminal 13 were bonded with the silver paste 15.

After that, epoxy resin 14 is applied to the cut surface portion of the capacitor element on the cathode lead terminal side to insulate the cut surface portion with an insulating mask, and then silver paste 15 is applied onto the cut surface portion subjected to the insulation mask to form the cathode layer 12 and the cathode. The lead terminal 13 was joined. Then, the anode part 16 of the capacitor element and the anode lead terminal 17 were joined by a spot welding machine 18.

This capacitor element was molded with epoxy resin to prepare a capacitor having a rated voltage of 16 V and a rated electrostatic capacity of 10 μF.

Initial characteristics were evaluated for 5000 capacitors for 10 capacitor element sheets manufactured by the above-exemplified method. The average value of the initial characteristics of the capacitor is that the electrostatic capacity at 120 Hz (abbreviated as Cap below)
The loss tangent at 10.5 μF and 120 Hz (hereinafter abbreviated as tanδ) is 0.68%, and the equivalent series resistance at 100 kHz (hereinafter ESR).
Was 52 mΩ, and the leakage current at 16 V (hereinafter abbreviated as LC) was 0.01 μA or less. The results are shown in Table 1.

Comparative Example 1 In Example, except that the cut surface portion of the capacitor element on the cathode lead terminal side was not coated with an epoxy resin and an insulating mask was not used, and the cathode layer of the capacitor element and the cathode lead terminal were joined with silver paste. A capacitor was manufactured in the same manner as in Example. No voltage could be applied to the obtained capacitor, which was in a short-circuited state, and the initial characteristics of the capacitor could not be measured. The results are shown in Table 1.

Comparative Example 2 In the example, the surface of the cathode layer of the capacitor element and the cathode lead terminal were joined by silver paste between the surface of the cathode layer and one end of the gold wire (wire diameter 30 μmφ). A capacitor was produced in the same manner as in the example except that the cathode lead terminal and the other end of the gold wire were spot welded. 1856 out of 5000 capacitors obtained
The individual pieces are defective in welding and the initial characteristics of the capacitor are Cap, tan
δ and ESR did not satisfy the ratings. For the remaining capacitors, Cap is 10.5 μF, tan δ is 0.66%,
The ESR was 55 mΩ and the LC was 0.01 μA or less. The results are shown in Table 1.

[0042]

[Table 1]

[0043]

According to the present invention, the other cathode of the capacitor element can be reliably joined to the cathode lead terminal by a simple process.
And it has excellent mass productivity.

[Brief description of drawings]

FIG. 1 is a plan view in which a first pattern and a fish bone-shaped conductive coating film are formed by a first insulating coating film.

FIG. 2 is a plan view in which a second pattern is formed with a second insulating coating film, showing a cut portion.

FIG. 3 is a sectional view taken along line ab of FIG.

FIG. 4 is a cross-sectional view in which a solid electrolyte layer and a cathode layer are formed.

FIG. 5 is a cross-sectional view in which a capacitor element is joined to a cathode and an anode lead terminal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum foil 2 Dielectric oxide film 3 Solid electrolyte layer formation part exposed by a 1st pattern 4 Anode extraction part exposed by a 1st pattern 5 1st insulating coating film 6 Conductive coating film 7 2nd insulation Coating 8 Part of the first insulating coating 9 Part of the conductive coating 10 Chemically polymerized polypyrrole film 11 Electrolytically polymerized polypyrrole film 12 Cathode layer 13 Cathode lead terminal 14 Insulating resin (epoxy resin) 15 Conductivity Resin (silver paste) 16 Anode part 17 Anode lead terminal 18 Spot welder head

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Fukuda 2470 Handa, Shibukawa City, Gunma Japan Research & Development Center, Carlite Co., Ltd.

Claims (4)

[Claims] 1. A step of forming a dielectric element oxide film on both surfaces of a valve metal and then forming a solid electrolyte layer and a cathode layer in a grid pattern to form a capacitor element sheet, and cutting the capacitor element sheet. , A step of obtaining a capacitor element, a step of joining one of the cathodes of the capacitor element and a cathode lead terminal, a step of applying an insulating resin to the cut surface of the capacitor element on the cathode lead side, the other of the cathode of the capacitor element and the cathode lead A method of manufacturing a solid electrolytic capacitor, comprising: a step of joining a terminal, a step of joining an anode of a capacitor element and an anode lead terminal, and a step of coating the capacitor element with a mold resin. 2. A step of forming a capacitor element sheet by forming a dielectric oxide film on both surfaces of a valve metal and then forming a solid electrolyte layer and a cathode layer in a grid pattern, and fixing the capacitor element sheet. Step, cutting capacitor element sheet to obtain capacitor element, joining capacitor element anode and anode lead terminal, joining capacitor element cathode one and cathode lead terminal, capacitor element cathode lead Of the solid electrolytic capacitor characterized by including the step of applying an insulating resin to the cut surface on the side, the step of joining the other cathode of the capacitor element and the cathode lead terminal, and the step of coating the capacitor element with the mold resin. Production method. 3. The insulating resin is at least one selected from the group consisting of epoxy resin, phenol resin, polyimide resin, polyester resin and polyphenylene sulfide resin, according to claim 1 or 2. Manufacturing method of solid electrolytic capacitor. 4. The method for producing a solid electrolytic capacitor according to claim 3, wherein the other one of the cathodes of the capacitor element and the cathode lead terminal are joined by using a silver paste.