JPH09260215A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make high the occurrence rate of the electrostatic capacity of a solid electrolytic capacitor while the effect of a reduction in a leakage current due to a chemical formation treatment is ensured and to lessen the equivalent series resistance of the capacitor by a method wherein after a chemical formation retreatment process, a process of rinsing a capacitor element is provided before an organic semiconductor impregnation process. SOLUTION: A second aluminium foil is performed an etching treatment and thereafter, a chemical formation treatment is performed to use a first aluminium foil formed with a dielectric film as an anode foil 1, the second aluminium foil performed the etching treatment is used as a cathode foil 2, the films 1 and 2 are wound via separator papers 31 and 32 and a capacitor element 7 is formed. After the element 7 is performed a chemical formation retreatment, the element 7 is rinsed before an organic semiconductor inpregnation process. Thereby, while the effect of a reduction in a leakage current due to the chemical formation retreatment is ensured, the occurence rate of the electrostatic capacity of a solid electrolytic capacitor can be made high and the equivalent series resistance of the capacitor can be lessened.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a solid electrolytic capacitor using an organic semiconductor such as TCNQ complex salt as an electrolyte.

[0002]

2. Description of the Related Art A solid electrolytic capacitor using a TCNQ complex salt as an electrolyte is disclosed in Japanese Patent Publication No. 62-51489. Here, TCNQ means 7,7,8,8-tetracyanoquinodimethane.

After the etching treatment, the aluminum foil on which the dielectric film is formed by chemical conversion treatment is used as an anode foil, the etched aluminum foil is used as a cathode foil, and the anode foil and the cathode foil are separator papers. A solid electrolytic capacitor in which a capacitor element is formed by winding through a coil, the capacitor element is subjected to a re-chemical conversion treatment, and then melted and liquefied TCNQ complex salt is impregnated, and the TCNQ complex salt is cooled and solidified to form an electrolyte. The manufacturing method is described in JP-A-3-136.
No. 227.

Here, the re-formation treatment for the capacitor element occurs when a dielectric film is formed on the cut surface of the anode foil or the joint with the lead terminal and the anode foil is wound together with the cathode foil and the separator paper. It is applied to repair the damage of the dielectric film and adjust the capacitance of the capacitor.

[0005]

However, when the re-formation treatment is performed, the re-formation treatment is generated on the surface of the dielectric film formed along the fine irregularities on the surface of the anode foil. Sludge such as aluminum hydroxide may remain, or adipic acid, phosphoric acid or salts thereof, which are solutes of the re-chemical conversion liquid, may adhere as a residue, and the capacitor element in this state is impregnated with the melted liquid TCNQ complex salt. When a capacitor is completed by cooling and solidifying, the appearance rate of capacitance may be low or the equivalent series resistance may be high.

The present invention solves the above problems.

[0007]

According to the method for manufacturing a solid electrolytic capacitor of the present invention, after the etching treatment, a chemical conversion treatment is applied to form a first metal foil, which is used as an anode foil, and the etching treatment is applied. The second metal foil as the cathode foil was used as a cathode foil, and the anode foil and the cathode foil were wound around a separator paper to form a capacitor element, which was subjected to re-chemical conversion treatment and then melted and liquefied. In a method for manufacturing a solid electrolytic capacitor in which an organic semiconductor is impregnated and the solidified organic semiconductor is cooled and solidified into an electrolyte, after the re-chemical conversion treatment step and before the organic semiconductor impregnation step, a step of washing the capacitor element with water is performed. It is characterized by being provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In a method for manufacturing a solid electrolytic capacitor according to an embodiment of the present invention, first, as shown in FIG. 1, after an etching treatment, a chemical conversion treatment is performed to form a dielectric film. The formed first aluminum foil is used as the anode foil 1, the second aluminum foil subjected to the etching treatment is used as the cathode foil 2, and the anode foil 1 and the cathode foil 2 are wound around the separator papers 31 and 32, The capacitor element 7 is formed.

In FIG. 1, reference numeral 4 is a winding tape.
Reference numerals 51 and 52 denote lead terminals for anode and cathode, and 61 and 62 denote lead bosses for anode and cathode. As materials for the anode foil and the cathode foil, so-called valve action metals such as tantalum and niobium are used in addition to the above-mentioned aluminum.

Next, the capacitor element is subjected to a re-chemical conversion treatment. The chemical conversion liquid used for the re-chemical conversion treatment contains at least one acid selected from adipic acid or an ammonium salt thereof, phosphoric acid or an ammonium salt thereof or a salt thereof as a solute, and water or a polyhydric alcohol such as ethylene glycol as a solvent. Those that are included as are suitable.

Next, the capacitor element is immersed in pure water for cleaning.

Thereafter, the capacitor element is heat-treated at a temperature of 200 ° C. or higher for the purpose of stabilizing the dielectric film.

On the other hand, powder of TCNQ complex salt is packed in an aluminum case and the aluminum case is heated to 250 to 300 ° C. to melt and liquefy the TCNQ complex salt.

Then, as shown in FIG. 2, the capacitor element 7 is inserted into the aluminum case 9 and immersed in the melted and liquefied TCNQ complex salt 8 to impregnate the capacitor element with the TCNQ complex salt and immediately cooled. TCNQ
After the complex salt is cooled and solidified, the opening of the aluminum case is filled with the epoxy resin 10 and sealed, and the aging treatment is performed to complete the solid electrolytic capacitor.

Here, the solid electrolysis of Examples 1 to 4 (sample symbols B, D, F, and H) according to the above-mentioned production method of the present invention and using various chemical conversion liquids as shown in Table 1 in the re-chemical conversion step. Capacitor (Rating 4WV-330μF, external diameter φ1
0 mm × L5 mm) and the production method and specifications of Examples 1 to 4 described above, but Comparative Example 1 in which the washing treatment after re-chemical conversion was omitted.
~ 4 (sample symbols A, C, E, G) prototype solid electrolytic capacitors, various characteristics (capacitance at 120 Hz: C, 12
The tangent of loss angle at 0 Hz: tan δ, the equivalent series resistance at 100 kHz: ESR, leakage current: LC) were measured.
Table 2 shows the results.

[0016]

[Table 1]

[0017]

[Table 2]

As can be seen by comparing Table 1 and Table 2,
While the leakage currents of the present invention example and the comparative example are equivalent, in the present invention example, the capacitance is larger, the tangent of the loss angle is smaller, and the equivalent series resistance is smaller than that of the comparative example. Has become.

[0019]

According to the present invention, in a solid electrolytic capacitor in which a capacitor element that has been subjected to re-chemical conversion treatment is impregnated with an organic semiconductor as an electrolyte, it is possible to secure an effect of reducing the leakage current by the chemical conversion treatment while maintaining the capacitance. It is possible to suppress the occurrence of problems such as a low appearance rate and a high equivalent series resistance.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a capacitor element used in an embodiment of the present invention.

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

[Explanation of symbols]

 1 Anode foil 2 Cathode foil 31 Separator paper 32 Separator paper 51 Anode lead terminal 52 Cathode lead terminal 7 Capacitor element 8 TCNQ complex salt as an electrolyte 9 Capacitor case 10 Sealing resin

Claims (3)

[Claims] 1. After the etching treatment, a first metal foil having a dielectric film formed by chemical conversion treatment is used as an anode foil, and a second metal foil subjected to the etching treatment is used as a cathode foil. A capacitor element is formed by winding the cathode foil and separator paper through the separator paper, and after subjecting the capacitor element to re-formation treatment, it is impregnated with a melt-liquefied organic semiconductor,
A method for manufacturing a solid electrolytic capacitor in which the organic semiconductor is cooled and solidified into an electrolyte, comprising a step of washing the capacitor element with water after the re-chemical conversion treatment step and before the organic semiconductor impregnation step. Manufacturing method of solid electrolytic capacitor. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein aluminum is used as a material for the anode foil and cathode foil, and a TCNQ complex salt is used as a material for the electrolyte. 3. The chemical conversion liquid used for the re-chemical conversion treatment,
The solid according to claim 2, comprising at least one acid selected from adipic acid or an ammonium salt thereof, phosphoric acid or an ammonium salt thereof, or a salt thereof as a solute, and water or a polyhydric alcohol as a solvent. Method of manufacturing electrolytic capacitor.