JPH09266141A - Manufacture of solid-state electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step of easily and simply connecting a cathode of a capacitor element to a cathode lead terminal, and also provide a method for fabricating an electrolytic capacitor which is good in productivity. SOLUTION: A dielectric oxide film is formed on both sides of a valve action metal, and then a capacitor element sheet obtained by forming solid-state electrolyte layers and cathode layers in an array of columns and rows is cut off to obtain capacitor elements. One of cathodes of the capacitor element is bonded to a cathode lead terminal, a metal foil is bonded to the other cathode of the capacitor element, and the metal foil and the cathode lead terminal are bonded together by an ultrasonic bonding process with use of metal wire. Then, the anode of the capacitor element is bonded to the anode lead terminal and finally the capacitor element is coated with molding resin to manufacture a solid-state 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 with an insulating coating. A method has been proposed in which a conductive polymer film layer and a cathode layer are sequentially formed on a surface 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, in Japanese Patent Laid-Open No. 6-34639, after forming a cathode layer and cutting each pattern with a cutter or the like, the cathode of the capacitor element and one of the lead wires are joined with silver paste, and the cathode lead terminal It is disclosed that the other end of the lead wire is joined by spot welding.

However, in the case of joining a cathode and a cathode lead terminal of a capacitor element using a 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. Further, since the wire diameter of the lead wire is small, there is a problem that welding defects frequently occur during spot welding.

[0004]

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

[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 cathodes of the capacitor element and a cathode lead terminal, a step of joining a metal foil to the other cathode of the capacitor element, the metal foil and the cathode lead terminal. In the manufacturing method of the method for manufacturing a solid electrolytic capacitor, including the step of bonding, the step of bonding the anode of the capacitor element and the anode lead terminal, and the step of coating the capacitor element with a mold resin, the metal foil and the cathode lead terminal are It is a method for manufacturing a solid electrolytic capacitor, which is characterized by ultrasonic bonding using a metal wire.

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.
As shown in FIG. 1, a first grid-like pattern of a portion 3 on which a solid electrolyte layer is formed and an anode leading portion 4 is left on both surfaces of an aluminum foil 1 on which a dielectric oxide film 2 is formed, leaving a first pattern. An insulating coating film 5 is formed. After that, a conductive coating film 6 to be a power feeding electrode during electrolytic polymerization is formed on the first insulating coating film 5. 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.

Subsequently, as shown in FIG. 2, a second insulating coating film 7 is formed while leaving a second grid-shaped pattern of the portion 3 on which the solid electrolyte layer is formed and the anode lead-out 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.

Then, 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 restoration, the aluminum foil on which the chemically polymerized polypyrrole film is formed is immersed in a chemical conversion solution 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 steps of joining one of the cathode of the capacitor element and the cathode lead terminal, the step of joining a metal foil to the other cathode of the capacitor element, and the step of joining the metal foil and the cathode lead terminal are as follows. Is.

As shown in FIG. 5, the back surface of the cathode layer 12 of the capacitor element and the cathode lead terminal 13 are joined with a conductive resin (silver paste) 16. Next, a part of the surface of the cathode layer of the capacitor element and the metal foil (silver foil) 14 are bonded with a conductive resin (silver paste) 16. After that, the metal foil (silver foil) 14 and the cathode lead terminal 13 are joined with the metal wire (silver wire) 15 by ultrasonic welding using a wire bonder.

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

The metal foil used in the present invention has a thickness
Examples include silver, nickel silver, copper or aluminum of 0.02 mm or more. The use of a metal foil having a thickness of less than 0.2 mm is not preferable because the metal foil is deformed by ultrasonic welding and the capacitor element is damaged.

The metal wire used in the present invention includes gold, silver, nickel or aluminum having a wire diameter of 20 to 500 μmφ, and aluminum is preferable from the economical point of view. If the wire diameter of the metal wire is less than 20 μmφ, the metal wire will melt during welding by ultrasonic welding, resulting in poor joining. If the wire diameter exceeds 500 μmφ, insufficient welding will result in poor joining.

The wavelength of ultrasonic waves at the time of joining by ultrasonic welding in the present invention is 50 to 150 kHz. If the wavelength is less than 50 kHz, welding will be insufficient and defective joints will occur. Further, if the wavelength exceeds 150 kHz, the metal wire is melted and the bonding becomes defective.

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

The spot welding machine 19 is used to join the anode part 17 of the capacitor element and the anode lead terminal 18. 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 joined in a simple process,
Solid electrolytic capacitors can be manufactured with high mass productivity.

[0032]

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 1 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) where a solid electrolyte layer is formed 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-shaped 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. Conductive current electropolymerization (0.3 mA / pin, 30 minutes) was performed between the conductive coating film 6 as an anode and a 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 FIG. 2 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 16. After that, the surface of the cathode layer 12 of the capacitor element and the silver foil
After bonding 14 (foil thickness 0.1 mm) with the silver paste 16, the silver foil 14 and the cathode lead terminal 13 are connected to the silver wire 15 (wire diameter
50 μmφ). Furthermore, the spot welder 19 was used to join the anode part 17 of the capacitor element and the anode lead terminal 18. Table 1 shows the joining conditions.

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

Initial characteristics evaluation was performed on 5000 capacitors for 10 capacitor element sheets manufactured by the method exemplified above. 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).
Is 57 mΩ, and the leakage current at 16 V (hereinafter abbreviated as LC) is 0.01 μA or less. Table 2 shows the results.

Example 2 In Example 1, after the surface of the cathode layer 12 of the capacitor element and the silver foil 14 (foil thickness 0.5 mm) were joined with the silver paste 16, the silver foil 14 was formed using a wire bonder (wavelength 60 kHz). A capacitor was produced in the same manner as in Example 1 except that the cathode lead terminal 13 and the cathode lead terminal 13 were joined with a silver wire 15 (wire diameter 200 μmφ). Table 1 shows the joining conditions.

The average values of the initial characteristics of the manufactured capacitors are as follows: Cap at 120 Hz, 10.4 μF, tan δ 0.65%, ES
R was 57 mΩ and LC was 0.01 μA or less. Table 2 shows the results
Shown in

Example 3 In Example 1, after the surface of the cathode layer 12 of the capacitor element and the silver foil 14 (foil thickness 1.0 mm) were joined with the silver paste 16, a silver bond 14 (wavelength 60 kHz) was used. A capacitor was produced in the same manner as in Example 1 except that the cathode lead terminal 13 and the cathode lead terminal 13 were joined with a silver wire 15 (wire diameter 50 μmφ). Table 1 shows the joining conditions.

The average values of the initial characteristics of the manufactured capacitors are as follows: Cap 10.7 μF, tan δ 0.67%, ESR 55 mΩ,
LC was 0.01 μA or less. Table 2 shows the results.

Example 4 In Example 1, after the surface of the cathode layer 12 of the capacitor element and the silver foil 14 (foil thickness of 0.1 mm) were joined with the silver paste 16, the silver foil 14 was applied using a wire bonder (wavelength 120 kHz).
And cathode lead terminal 13 with silver wire 15 (wire diameter 400 μmφ)
A capacitor was produced in the same manner as in Example 1 except that the connection was made in. Table 1 shows the joining conditions.

The average values of the initial characteristics of the manufactured capacitors are as follows: Cap is 10.6 μF, tan δ is 0.68%, ESR is 55 mΩ,
LC was 0.01 μA or less. Table 2 shows the results.

Comparative Example 1 A capacitor was manufactured in the same manner as in Example 1 except that a silver foil having a foil thickness of 0.01 mm was used. Table 1 shows the joining conditions.

Of the 5000 capacitors that were produced, the one obtained by deforming the silver foil due to the shock during ultrasonic welding was 4465.
Generated, the initial characteristics of the capacitor Cap, tan δ, ES
R greatly fluctuated and LC greatly increased from 5 A to short. Table 2 shows the results.

Comparative Example 2 A capacitor was manufactured in the same manner as in Example 1 except that a silver wire having a wire diameter of 10 μm was used.
Table 1 shows the joining conditions.

Of the 5000 capacitors produced, 2428 bonding defects due to fusing of the silver wire on the cathode lead terminal side occurred, and the initial characteristics of the capacitor were Cap, tan δ and ESR.
Did not meet the rating. For the remaining capacitors, Cap is 10.5μF, tanδ is 0.69%, and ESR is 52m.
Ω, LC was 0.01 μA or less. Table 2 shows the results.

Comparative Example 3 A capacitor was manufactured in the same manner as in Example 1 except that a silver wire having a wire diameter of 600 μmφ was used.
Table 1 shows the joining conditions.

Of the 5000 capacitors produced, 1673 defective joints due to insufficient adhesion of the silver wire to the silver foil and the cathode lead terminal occurred due to insufficient ultrasonic output, and the initial characteristics Cap, tan δ and ESR of the capacitor were The rating could not be satisfied. For the remaining capacitors, Cap is 10.4
μF, tanδ 0.66%, ESR 56mΩ, LC 0.01μA
It was below. Table 2 shows the results.

Comparative Example 4 In Example 1, the wavelength of ultrasonic waves during ultrasonic bonding was set to 40
A capacitor was produced in the same manner as in Example 1 except that kHz was used. Table 1 shows the joining conditions.

Of the 5000 capacitors produced, 3291 defective joints due to non-adhesion of the silver wire to the silver foil and the cathode lead terminal occurred, and the initial characteristics of the capacitors Cap, ta
nδ and ESR did not satisfy the ratings. For the remaining capacitors, Cap is 10.6 μF and tan δ is 0.67.
%, ESR was 56 mΩ, and LC was 0.01 μA or less. Table 2 shows the results.

Comparative Example 5 In Example 1, the wavelength of ultrasonic waves during ultrasonic bonding was 16
A capacitor was produced in the same manner as in Example 1 except that the frequency was 0 kHz. Table 1 shows the joining conditions.

Out of 5000 capacitors produced, 4826 bonding defects due to fusing of the silver wire occurred, and the initial characteristics Cap, tan δ, and ESR of the capacitor could not satisfy the ratings. For the remaining capacitors, Cap is 10.6
μF, tanδ 0.66%, ESR 55mΩ, LC 0.01μA
It was below. Table 2 shows the results.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

According to the present invention, a small-sized and large-capacity solid electrolytic capacitor can be manufactured by a simple process. Particularly, the joining of the capacitor element cathode and the cathode lead terminal is performed by ultrasonic welding through a metal foil. Can be joined and 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 Electropolymerized polypyrrole film 12 Cathode layer 13 Cathode lead terminal 14 Metal foil (silver foil) 15 Metal wire (silver) Wire) 16 Conductive resin (silver paste) 17 Anode section 18 Anode lead terminal 19 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 (6)

[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 cathode of the capacitor element and a cathode lead terminal, a step of joining a metal foil to the other cathode of the capacitor element, a step of joining the metal foil and a cathode lead terminal, In a method of manufacturing a solid electrolytic capacitor including 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 molding resin, the metal foil and the cathode lead terminal are ultrasonic waves using a metal wire. A method for manufacturing a solid electrolytic capacitor, which comprises bonding. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the metal foil is silver, nickel silver, copper or aluminum. 3. The method for producing a solid electrolytic capacitor according to claim 2, wherein the thickness of the metal foil is 0.02 mm or more. 4. The metal wire is gold, silver, nickel or aluminum.
The method for manufacturing the solid electrolytic capacitor according to any one of 1. 5. The method for producing a solid electrolytic capacitor according to claim 4, wherein the wire diameter of the metal wire is 20 to 500 μmφ. 6. The method for producing a solid electrolytic capacitor according to claim 1, wherein the ultrasonic wave has a wavelength of 50 to 150 kHz.