JPH04352409A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a solid electrolytic capacitor in which recovering properties of an oxide film is improved and an equivalent series resistance value is remarkably improved. CONSTITUTION:A winding element in which an anode foil and a cathode foil are wound through a separator, is impregnated with organic semiconductor which is dissolved to be liquefied thereby to form a capacitor element. Then, in order to improve recovering properties of an oxide film of the capacitor element, the interior of the element is impregnated with pure water. In order to prevent the semiconductor from being dissolved in water content remaining in the element, a method for manufacturing a solid electrolytic capacitor comprising the steps of freezing the water content of the capacitor element, and removing the frozen water content by sublimating, is provided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses TCNQ (
The present invention relates to an organic semiconductor solid electrolytic capacitor using 7,7,8,8-tetracyanoquinodimethane) salt.

0002

[Prior Art] Conventionally, it has been proposed to use an organic semiconductor, particularly a TCNQ salt, as a solid electrolyte in a solid electrolytic capacitor. Disclosed.

[0003] First, a metal foil having a valve action such as aluminum, tantalum, niobium, etc., whose surface has been provided with an oxide film by anodizing or anodizing, and a cathode foil are wound through a separator paper to form a winding element. do.

[0004] Next, an appropriate amount of TCNQ salt powder is packed into an aluminum case under moderate pressure, and this is melted and liquefied at 250 to 300°C, and a preheated winding element is quickly inserted therein. Then, the element is cooled and liquefied together with the aluminum case, and the winding element is fixed inside the case. Subsequently, in order to improve the repairability of the oxide film, the capacitor element formed by impregnating the winding element with TCNQ salt is immersed in pure water, and the pure water is impregnated to the inside of the element under reduced pressure. . and 8
The capacitor was left for 1 to 8 hours at 5 to 105°C (the standing time is approximately proportional to the external shape of the capacitor element), and the moisture in the capacitor was evaporated and removed, then sealed with resin and subjected to voltage treatment (aging). It is completed through the following steps.

[0005]

[Problems to be Solved by the Invention] In the conventional manufacturing method as described above, after impregnating the inside of a capacitor element impregnated with TCNQ salt with pure water, the moisture inside the capacitor element is removed at a temperature of about 100°C. Because the capacitor element is dried, the TCNQ salt impregnated inside the element will slightly dissolve in the residual moisture inside the capacitor element during this drying time (note that at room temperature (below 30°C), the TCNQ salt will dissolve slightly in the residual moisture inside the capacitor element. (almost insoluble in water). Therefore, there is a drawback that the equivalent series resistance (ESR) increases.

[0006]

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems, and involves impregnating a winding element in which an anode foil and a cathode foil are wound with a separator interposed therebetween with a melted and liquefied organic semiconductor. a step of impregnating pure water into the inside of a capacitor element formed by cooling and solidifying the organic semiconductor impregnated in the winding element; freezing the moisture in the capacitor element;
The method of manufacturing a solid electrolytic capacitor also includes the step of sublimating and removing the frozen water.

[0007]

[Function] According to the method of manufacturing a solid electrolytic capacitor according to the present invention, the repairability of the oxide film is improved due to the step of immersing the capacitor element in pure water.

Furthermore, because of the process of freezing and sublimating the moisture impregnated into the capacitor element, the organic semiconductor hardly dissolves in the residual moisture of the capacitor, thereby preventing an increase in equivalent series resistance.

[0009]

[Example] An example of the present invention will be described.

First, an etched and chemically-treated aluminum foil is used as an anode foil, and a separator is sandwiched between the anode foil and the opposing cathode foil, and the aluminum foil is wound into a cylindrical shape to form a winding element. Then, a powder of TCNQ salt (for example, a mixture of equal amounts of N-n-butylisoquinolinium TCNQ2 or N,N-pentamethylene rutidinium 2 TCNQ4 and N-phenethyl rutidinium TCNQ2) is stored in a case, Temperatures above the melting point (e.g. 290-30
The above-described wound element is impregnated with TCNQ salt at 0° C.) to form a capacitor element. Furthermore, after the impregnation, the case is cooled and the TCNQ salt impregnated into the capacitor element is cooled and solidified, thereby fixing the capacitor element within the case.

Furthermore, the TCNQ salt-impregnated capacitor element is immersed in pure water, and the pressure is reduced to impregnate the inside of the element with pure water. Then, the moisture in the capacitor element was reduced to -70
It is frozen at ℃, and the frozen water is removed by sublimation while the pressure is reduced below water vapor pressure using a vacuum pump or the like.

Finally, the opening of the case is sealed with resin, elastic material, etc., and the rated voltage of the capacitor is applied (aging) at 125° C. for about 1 hour to complete the intended solid electrolytic capacitor.

Table 1 shows the leakage current values and equivalent series resistance values of the capacitor according to the present invention and the conventional example.

[0014]

[Table 1]

In Table 1, the rated voltages of the capacitors (A) to (D) are all 25V. In addition, the leakage current is 2
The values are the values after 10 minutes of application of 5V, and the average values of each 10 samples are shown. ESR is an equivalent series resistance value at 100 kHz, and indicates the average value of each 10 samples.

[0016]

Effects of the Invention As described above, in the present invention, since the TCNQ salt-impregnated element is immersed in pure water, the repairability of the oxide film is increased.

Furthermore, since the manufacturing method involves cooling, solidifying, and sublimating the residual moisture, the TCNQ salt does not dissolve in the residual moisture, and the equivalent series resistance value can be significantly improved.

Claims (1)

[Claims] 1. A step of impregnating a molten and liquefied organic semiconductor into a winding element in which an anode foil and a cathode foil are wound through a separator, and cooling and solidifying the organic semiconductor impregnated into the winding element. A method for producing a solid electrolytic capacitor comprising the steps of: impregnating the inside of a capacitor element with pure water; freezing moisture in the capacitor element; and removing the frozen moisture by sublimation.