JPS6251489B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a method for producing a solid electrolytic capacitor using an organic semiconductor made of TCNQ salt as a solid electrolyte. (b) Conventional technology TCNQ as a solid electrolyte for solid electrolytic capacitors
It is already known that organic semiconductors consisting of salts can be used. In this case, the solid electrolyte is directly attached to a film-forming metal such as aluminum that has an oxide film, but in a different form, an anode foil and a cathode foil are rolled up with a separator paper in between, and the solid electrolyte is attached to the separator paper. Impregnation with the above-mentioned solid electrolyte has also been proposed as an invention in Japanese Patent Application No. 116861/1983. Note that TCNQ means 7, 7, 8, 8 tetracyanoquinodimethane. (c) Problems to be Solved by the Invention The present invention aims to improve the latter type of wound capacitor, and more specifically, increases the degree of impregnation of the solid electrolyte into the separator paper. By increasing the recrystallized TCNQ salt, the capacitor characteristics such as an increase in capacitance and a decrease in tan δ and ESR (equivalent series resistance) are obtained. (d) Means for Solving the Problems The present invention provides the following features: (A) A winding element having a separator paper is heated at 400°C or less as a preparatory step for recrystallizing TCNQ salt on the separator paper. (B) storing TCNQ salt in a bottomed cylindrical aluminum case and melting and liquefying the TCNQ salt by heating the case above the melting point and below 300°C; , (C) impregnating the separator paper with the TCNQ salt by immersing the winding element in the TCNQ salt, and (D) cooling the case to impregnate the TCNQ salt impregnated into the separator paper. This is a method for manufacturing a solid electrolytic capacitor, which includes a step of recrystallization. (e) Effect Since the density of separator paper decreases due to carbonization treatment, liquefied TCNQ salt is easily sucked into the winding element, and as a result, the degree of impregnation of TCNQ salt increases.
Increase the amount of TCNQ salt that recrystallizes. (F) Example As an example of the present invention, a solid electrolyte was impregnated into a winding element for a rated 25V, in which chemically formed aluminum foil was used as an anode foil, aluminum etched foil was used as a cathode foil, and Manila paper was used as a separator paper. The case will be explained together with the manufacturing process. First, as a preparatory step for recrystallizing TCNQ salt on separator paper, the above winding element was placed in air.
Heating is performed at 250°C for 30 minutes or more to carbonize the separator paper. On the other hand, as a solid electrolyte, N-(n-propyl)-
A TCNQ salt of isoquinolinium is prepared. That way
The preparation of TCNQ salt itself was conducted by J.Am.Chem.Soc.
Vol. 84, P. 3374-3387 (1962), but to put it simply, N-(n-
By reacting isoquinolinium iodine with TCNQ in a 1:1.3 molar ratio in acetonitrile, N-(n-propyl)-
TCNQ complex salt of isoquinolinium is made. Hereinafter, this salt will be simply referred to as TCNQ salt. Next, the TCNQ salt powder is placed in a cylindrical aluminum case with a bottom, and the case is heated on an iron plate maintained at a temperature above the melting point of the TCNQ salt and below about 300°C, more preferably between 280°C and 290°C. Hold. Furthermore, such a case will ultimately become the envelope of the capacitor. The melting point of the above TCNQ salt is 210℃
~220°C, therefore, the TCNQ salt in the case melts and liquefies due to the above heating. In the next step, the winding element prepared in advance is immersed in the liquefied TCNQ salt inside the case, and the separator paper is impregnated with the TCNQ salt. In the next step, the case is immediately immersed in water at room temperature to cool it down. Such cooling should begin as soon as the liquefaction of the TCNQ salt is completed. That is, if the TCNQ salt is kept in a liquid state for a long period of time, the TCNQ salt will foam violently and become a substantially electrical insulator. More specifically,
The time from liquefaction to insulator is longer as the liquefaction temperature of TCNQ salt is lower;
In the case of 280°C to 290°C, the cooling start timing is set within 1 minute, more preferably within 15 seconds after the completion of liquefaction. Further, it is preferable that the winding element be preheated to approximately the same temperature as the heating temperature of the TCNQ salt immediately before being immersed. Through this process, the separator paper of the winding element is impregnated with liquid TCNQ salt, and the TCNQ salt impregnated into the subsequent cooling separator paper recrystallizes and exhibits a high electrical conductivity of 20-30Ωcm (25℃). Forms a solid electrolyte. Finally, the opening of the case is sealed with resin with the tips of the anode lead and cathode lead exposed to complete the desired solid electrolytic capacitor. The table below shows the characteristics of the solid electrolytic capacitor of this example. In the table, the first, second, and third examples are cases where the duration of the carbonization treatment was 30 minutes, 1 hour, and 2 hours, respectively, and the reference example is a case where only the carbonization treatment was not performed at all. be. In addition, capacitance C and tan
δ is a measured value at 120 Hz, ESR is a measured value at 100 kHz, ΔC/C is the capacitance change rate based on 20° C., and LC/30″ is the average leakage current after 30 seconds.

【table】

[Table] From the above table, it is clear that if the separator paper is carbonized as in this example, the effects of increasing capacitance and decreasing tan δ and ESR will appear. This effect of the carbonization process is due to the fact that the fibers of the separator paper become thinner due to carbonization, increasing the gaps between the fibers, increasing the degree of impregnation of the solid electrolyte into the separator paper, and increasing the amount of recrystallized TCNQ salt. be. The table below shows carbonization treatment (temperature 250℃)
This shows the duration of the process and the change in weight of the separator paper, which means the degree of fineness of the fibers due to carbonization.

[Table] If the carbonization temperature is too high, only the fibers near the surface of the separator paper will be excessively carbonized, and the carbonization will not proceed sufficiently to the inner fibers. Therefore, the processing temperature is 400
The temperature should be set at 300°C or lower, preferably 300°C or lower. Also, as is clear from the table above, the more time is spent, the more carbonization progresses, but excessive carbonization will lead to a decrease in the electrical insulation of the separator paper and cracks.
Therefore, the degree of carbonization is preferably 90% to 40% of the original weight of the separator paper. In the above embodiments, the aluminum foil is replaced with another film-forming metal foil such as tantalum foil, kraft paper is used as the separator paper, and N-(isopropyl)-quinolinium, N-(n-propyl) is used as the solid electrolyte. -quinolinium, N-
It is possible to use each TCNQ complex salt of (isopropyl)-isoquinolinium and can be implemented in the same manner. As is clear from the above description, the present invention provides a solid electrolytic capacitor in which an anode foil and a cathode foil are wound up with a separator paper in between, and the separator paper is impregnated with an organic semiconductor made of TCNQ salt as a solid electrolyte. Characteristics can be improved.

Claims (1)

[Claims] 1 (A) As a preparatory step for recrystallizing TCNQ salt in the separator paper, a winding element having the separator paper is heated at 400°C or less to carbonize the separator paper. (B) storing the TCNQ salt in a bottomed cylindrical aluminum case and melting and liquefying the TCNQ salt by heating the case above the melting point and below 300°C; (C) adding the TCNQ salt to the (D) recrystallizing the TCNQ salt impregnated into the separator paper by cooling the case; Method of manufacturing solid electrolytic capacitors. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the TCNQ salt is a TCNQ salt of N-(n-propyl)-isoquinolinium.