JP2001076976A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a slid electrolytic capacitor, using conductive polymer in which initial leakage current characteristic can be improved. SOLUTION: In this method for manufacturing a solid electrolytic capacitor using conductive polymer as an electrolyte, a capacitor element 1 in which conductive polymer is formed is immersed in a dissolved solder solution before being sealed in a metallic case or a resin armor, and power supply aging is carried out by setting the anode side of the capacitor as a positive potential and the solder solution side as a negative potential.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer as an electrolyte.

[0002]

2. Description of the Related Art As a solid electrolyte, a solid electrolytic capacitor using a conductive polymer such as polypyrrole, polythiophene, polyfuran, and polyaniline has attracted attention.

In a solid electrolytic capacitor using a conductive polymer as an electrolyte, for example, as shown in FIG. 1, a capacitor element 1 in which an anodized foil 2 and a counter cathode foil 3 are wound via a separator paper 4 is formed. Then, an anode lead wire 7 and a cathode lead wire 8 are led out to the anodized foil 2 and the opposing cathode foil 3 via the lead tab terminals 6, respectively. Reference numeral 5 denotes a winding tape. Such a capacitor element 1 is immersed in a chemical polymerization solution prepared by mixing a monomer and an oxidant at an appropriate weight ratio to form a conductive polymer between both electrodes of the capacitor element 1.

The anodized foil 2 is formed by subjecting a foil made of a valve metal such as aluminum, tantalum, or niobium to an etching treatment for surface roughening and then immersing the foil in a chemical conversion solution (electrolyte solution). (Electrolytic oxidation treatment) to form a chemical conversion film (dielectric oxide film).

As shown in FIG. 2, the capacitor element 1 on which the conductive polymer is formed passes the anode lead wire 7 and the cathode lead wire 8 through the through-hole 11 of the butyl rubber 10 for sealing. The metal case 9 is housed in the cylindrical metal case 9.
The opening is sealed by subjecting it to horizontal drawing and curling. Further, instead of the butyl rubber 10 for sealing, sealing with resin is also performed.

[0006]

However, in a conventional solid electrolytic capacitor using a conductive polymer, a capacitor element is housed in a metal case and sealed for the purpose of repairing damage to anodized foil, and the rated voltage is reduced. 125 ° C while applying
Although the aging process is performed to a certain extent, there is still a problem that the initial leakage current of the capacitor is very large. This is because, in a solid electrolytic capacitor using a conductive polymer, there are many steps that involve a thermal load in the manufacturing process, and as a result, the oxide film on the anodized aluminum foil is greatly damaged, and the aging treatment after sealing the capacitor element is performed. Would not be fully restored.

Accordingly, the present invention provides a method of manufacturing a solid electrolytic capacitor using a conductive polymer, which can improve initial leakage current characteristics.

[0008]

According to the present invention, there is provided a method for manufacturing a solid electrolytic capacitor using a conductive polymer as an electrolyte, wherein the capacitor element having the conductive polymer is formed by a metal case. Alternatively, prior to sealing with a resin exterior, the capacitor element is immersed in a dissolved solder solution, and the current-aging is performed by setting the anode side of the capacitor element to a positive potential and setting the solder liquid side to a negative potential.

Further, the present invention is characterized in that the voltage applied during the energization aging is lower than the rated voltage of the capacitor element.

Further, the present invention provides a method for controlling the temperature of the solder
It is characterized in that current aging is performed at a temperature of 0 ° C. or more and 300 ° C. or less.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid electrolytic capacitor according to one embodiment of the present invention has the same configuration as that of FIG. 1. Hereinafter, a manufacturing method of the present invention will be described in detail with reference to FIG. [Embodiment 1] First, an aluminum foil having a dielectric oxide film formed on its surface by performing an etching treatment and a chemical conversion treatment is used as an anodized chemical foil 2, and a cylindrical member is provided between the aluminum foil and the opposing cathode foil 3 via a separator paper 4. The capacitor element 1 wound in a shape is formed. An anode lead wire 7 and a cathode lead wire 8 are pulled out from the anode foil 2 and the opposing cathode foil 3 via lead tab terminals 6, respectively. Reference numeral 5 denotes a winding tape.

Next, the capacitor element 1 is immersed in a chemical polymerization solution prepared by mixing iron (III) p-toluenesulfonate containing at least 50% of n-butyl alcohol as a diluent and 3,4-ethylenedioxythiophene. 200 ° C
Heat treatment is performed at the above temperature to form a conductive polymer layer between both electrodes of the capacitor element 1.

The capacitor element on which the conductive polymer layer is formed is immersed in a solder solution dissolved at 225 ° C., the anode lead 7 of the capacitor element 1 is connected to the positive electrode, and the solder liquid is connected to the negative electrode. Conduction aging is performed for 20 seconds (hereinafter, such aging processing is referred to as solder aging).

After completion of the solder aging, the anode lead wire 7 and the cathode lead wire 8 of the capacitor element 1 are passed through the through hole 11 of the butyl rubber 10 for sealing as shown in FIG. The metal case 9 is sealed by performing horizontal drawing and curling at the end of the opening of the metal case 9. Then, in an environment of 125 ° C, 2
A solid electrolytic capacitor was completed through an aging treatment of 0 V (rated voltage) for 1 hour.

The rating of the capacitor element of this embodiment is as follows:
20V, 56μF, external dimensions are φ8.3mm × L
It was 6.3 mm. Example 2 A solid electrolytic capacitor was completed under the same conditions as in Example 1 except that the voltage applied during solder aging was 12 V. Example 3 A solid electrolytic capacitor was completed under the same conditions as in Example 1 except that the applied voltage at the time of solder aging was 10 V. Example 4 A solid electrolytic capacitor was completed under the same conditions as in Example 1 except that the applied voltage at the time of solder aging was 8 V. [Conventional Example 1] A solid electrolytic capacitor was completed under the same conditions as in Example 1 except that the solder aging was omitted.

Twenty samples of each of the above embodiment and the conventional example were prepared, and their initial electric characteristics were capacitance (C) at 120 Hz, loss tangent (tan δ) at 120 Hz,
An average value of equivalent series resistance (ESR) at 100 kHz and a yield (LC yield) of a non-defective product having a leakage current of 0.2 CV or less after 60 seconds from application of a rated voltage were measured. Table 1 shows the results.

[0017]

[Table 1]

As is clear from Table 1, after forming a conductive polymer (polythiophene) as an electrolyte in a capacitor element, solder aging is performed prior to enclosing and sealing in a metal case, so that the capacitance (C), The characteristics of the loss tangent (tan δ) and the equivalent series resistance (ESR) are not deteriorated, the initial leakage current is reduced, and the LC yield is greatly improved. Further, it is preferable that the applied voltage at the time of solder aging is lower than the rated voltage.

Next, an embodiment of a solid electrolytic capacitor using a sintered body made of a valve metal as an anode of a capacitor element will be described with reference to FIG. Example 5 First, a sintered body of tantalum metal powder as a valve action metal was used as an anode body 12 and subjected to a chemical conversion treatment in an electrolytic solution of a phosphoric acid aqueous solution.
3 is formed.

Next, the capacitor element is immersed in a chemical polymerization solution comprising 3,4-ethylenedioxythiophene, iron (III) p-toluenesulfonate, and isopropyl alcohol, and then dried at about 100.degree. A conductive polymer layer 14 made of polythiophene is formed on the layer 13.

Thereafter, the capacitor element having the graphite layer 15 formed on the conductive polymer layer 14 is immersed in a solder solution dissolved at 240 ° C., the anode body is connected to the positive electrode, the solder solution is connected to the negative electrode, and the applied voltage is reduced. The solder aging is performed at 20 V for 20 seconds.

After the solder aging, the graphite layer 1
A silver paste layer 16 is formed on 5, and a cathode terminal 17 is connected thereto via a conductive adhesive 20, and an anode terminal 18 is connected to the anode body 12. Finally, such a capacitor element was sealed with a resin sheath 19, and subjected to an aging treatment at 25 V (rated voltage) for 1 hour under an environment of 125 ° C., thereby completing a solid electrolytic capacitor.

The rating of the capacitor element of this embodiment is as follows:
25V, 22μF, external dimensions are 7.3mm × 4.3
mm × 3.1 mm. Example 6 A solid electrolytic capacitor was completed under the same conditions as in Example 5 except that the voltage applied during solder aging was changed to 15 V. [Conventional example 2] A solid electrolytic capacitor was completed under the same conditions as in Example 5 except that the solder aging was omitted.

Twenty samples of each of the above embodiment and the conventional example were prepared, and their initial electric characteristics were capacitance (C) at 120 Hz, tangent of loss angle (tan δ) at 120 Hz,
The leakage current after 60 seconds from the application of the average value of the equivalent series resistance (ESR) at 100 kHz and the rated voltage is 0.05 CV
The following (non-defective) yields (LC yields) were measured. Table 2 shows the results.

[0025]

[Table 2]

As is clear from Table 2, even in a solid electrolytic capacitor using a sintered body as an anode, after forming a conductive polymer (polythiophene) as an electrolyte in a capacitor element, solder aging is performed before sealing with a resin sheath. , The initial leakage current is reduced and the LC yield is greatly improved without deteriorating the characteristics of capacitance (C), loss tangent (tan δ), and equivalent series resistance (ESR). ing.

Further, in the winding type capacitors shown in Examples 1 to 4 and the sintered type type capacitors shown in Examples 5 to 6, the temperature of the solder liquid at the time of solder aging is set to 1
Table 3 shows initial electrical characteristics at 60 ° C. and 320 ° C. The voltage applied during solder aging was 8V.

[0028]

[Table 3]

As is clear from Table 3, when the temperature of the solder liquid is 160 ° C., the effect on LC is low, and when the temperature is 320 ° C., although the effect on LC is obtained, the ESR increases and C decreases. Such a problem comes out. The present applicant has conducted various experiments on the temperature of the solder liquid at the time of solder aging, and found that the solder liquid is effective when the temperature of the solder liquid is in the range of 180 ° C. or more and 300 ° C. or less.

[0030]

According to the method for manufacturing a solid electrolytic capacitor of the present invention, the capacitor element on which the conductive polymer is formed is immersed in a dissolved solder solution before being sealed with a metal case or a resin sheath. By conducting energizing aging with the anode side of the capacitor element at a positive potential and the solder liquid side at a negative potential, the initial leakage current can be reduced without deteriorating the characteristics of capacitance, tangent of loss angle, and equivalent series resistance. The size can be reduced, and the LC yield can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a first solid electrolytic capacitor element according to an embodiment of the present invention.

FIG. 2 is a sectional view of a first solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 3 is a sectional view of a second solid electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anodized chemical foil 3 Opposite cathode foil 4 Separator paper 5 Retaining tape 6 Lead tab terminal 7 Anode lead wire 8 Cathode lead wire 9 Metal case 10 Sealing butyl rubber 11 Through hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Rikizo Yamaguchi 217 Fukumo, Omachi-cho, Kishima-gun, Saga Prefecture Inside Saga Sanyo Kogyo Co., Ltd. 217 mother Saga Sanyo Kogyo Co., Ltd. (72) Inventor Kimichi Nakano Okamachi, Kishima-gun, Saga prefecture Fukumo 217 uchi Saga Sanyo Kogyo Co., Ltd. 217 Fukumo Saga Sanyo Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A method for manufacturing a solid electrolytic capacitor using a conductive polymer as an electrolyte, wherein the capacitor element on which the conductive polymer is formed is sealed with a molten solder liquid prior to sealing with a metal case or a resin sheath. Soak,
A method for manufacturing a solid electrolytic capacitor, wherein current aging is performed by setting the anode side of the capacitor element to a positive potential and the solder liquid side to a negative potential. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the voltage applied during the energization aging is lower than the rated voltage of the capacitor element. 3. The temperature of the solder liquid is 180 ° C. or more and 300 ° C.
2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the current aging is performed at a temperature of not more than ℃.