JPH0467331B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a solid electrolytic capacitor using an organic semiconductor made of TCNQ salt as a solid electrolyte. (b) Conventional technology As a solid electrolyte for solid electrolytic capacitors
It is already known that organic semiconductors consisting of TCNQ 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. What is TCNQ? 7, 7, 8,
8 Tetracyanoquinodimethane. In addition, the technology of carbonizing the separator paper of electrolytic capacitors is described in Japanese Patent Application Laid-Open No. 135921/1983 (H01G9/02), and the purpose of this is to increase the amount of electrolyte (liquid) retained. However, the TCNQ salt (solid) of the present invention described below
This technology is different from the technology that increases the amount of retention. In addition, this conventional separator paper is used to separate the two electrodes and prevent shortening in capacitors, where the anode foil and the negative electrode foil always face each other with a liquid interposed between them, and there is a risk of shortening between the two electrodes. If the separator paper is carbonized excessively, it will lose its mechanical strength, and there is a risk that the gap between the two electrodes will be shot due to the pressure applied when the open end of the metal case is curled or during actual use. (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, thereby improving By increasing the crystallized 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 solid electrolytic capacitor of the present invention is manufactured as follows. That is, (A) heating the winding element having the separator paper at 400° C. or lower to carbonize the separator paper as a preparatory step for recrystallizing the TCNQ salt on the separator paper; (B) carbonizing the separator paper; TCNQ on bottom cylindrical aluminum case
(C) immersing the winding element in the TCNQ salt to coat the separator paper with the TCNQ salt; (D) By cooling the case, the TCNQ salt impregnated into the separator paper is recrystallized to produce a solid electrolytic capacitor. It goes without saying that the TCNQ salt used as the electrolyte in the solid electrolytic capacitor of the present invention has a high conductivity that can be used as an electrolyte for a capacitor after being cooled and solidified. (e) Effect: Since the density of separator paper decreases due to carbonization, the liquefied TCNQ salt is easily sucked into the winding element, which increases the degree of TCNQ salt impregnation and increases the amount of recrystallized TCNQ salt. let Furthermore, if the separator paper of the present invention does not shorten between the two electrodes only during the impregnation process (step (C) above), it will not work in subsequent processes and during actual use.
Recrystallization (solidification) of the TCNQ salt maintains the distance between the two poles, so there is no fatal problem even if the carbonization process is performed excessively. Therefore, the separator paper of the present invention can be carbonized up to 40% of its original weight, taking into account the reduction in electrical insulation and cracking, and as a result, a sufficient amount of recrystallization of TCNQ salt can be secured. . (F) Example As an example of the present invention, a solid electrolyte was impregnated into a winding element for a rated 25V in which aluminum chemically formed 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 the separator paper, the winding element is heated in air at 250° C. for 30 minutes or more, thereby carbonizing the separator paper. On the other hand, as a solid electrolyte, N-(n-propyl)-
A TCNQ salt of isoquinolinium is prepared. The preparation of such 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 bottomed cylindrical aluminum case, and an iron plate is kept at a temperature above the melting point of the TCNQ salt and below about 300°C (below the thermal decomposition temperature), more preferably between 280°C and 290°C. The case is heated and held at the top. Furthermore, such a case will ultimately become the envelope of the capacitor. the above
The melting point of TCNQ salt is 210°C to 220°C, so the TCNQ salt in the case is melted and liquefied by 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. Next, in the process, 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. i.e. for a long time, above
If the TCNQ salt is kept in a liquid state, it will foam violently and become a near-electrical insulator. More specifically, the time from liquefaction to insulator is longer as the liquefaction retention temperature of TCNQ salt is lower, and as mentioned above, when it is between 280℃ and 290℃, the cooling start time is 1 minute after liquefaction is completed. It is set within 15 seconds, more preferably within 15 seconds. 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,
TCNQ impregnated into separator paper then cooled
The salt recrystallizes to form a solid electrolyte with 20-30 Ωcm (25°C) higher conductivity. 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 tanδ
is the measured value at 120Hz, ESR is the measured value at 100kHz, ΔC/C is the capacitance change rate with reference to 20℃,
LC/30″ represents the average leakage current after 30 seconds, respectively.

【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-
(Isopropyl)-isoquinolinium also has each TCNQ
Any use of complex salts is possible and can be implemented as well. (G) Effects of the Invention As is clear from the above explanation, the solid electrolytic capacitor of the present invention is produced by winding up an anode foil and a cathode foil with a separator paper in between, and applying TCNQ to the separator paper.
This is a solid electrolytic capacitor impregnated with an organic semiconductor made of salt as a solid electrolyte, and the separator paper of the present invention can be used in subsequent steps unless the distance between the two electrodes is shortened only in the impregnation step (step (C) above). In actual use, the distance between the two extremes is maintained by recrystallization (solidification) of the TCNQ salt, so there is no fatal problem even if the carbonization treatment is performed excessively. Therefore, the separator paper of the present invention can be carbonized up to 40% of its original weight, taking into account the reduction in electrical insulation and cracking, and as a result, a sufficient amount of TCNQ salt can be recrystallized. .
In this way, the characteristics can be improved.

Claims (1)

[Scope of Claims] 1. A capacitor winding element in which a separator paper is sandwiched between a cathode foil and an anode foil, and both negative and anode electrode foils of the capacitor winding element are carbonized by heating at 400°C or less. A solid electrolytic capacitor comprising: a solid electrolyte in which the separator paper is melted and impregnated with TCNQ salt that is meltable and has a conductivity that can be used as an electrolyte for a capacitor after being cooled and solidified. 2. A container containing a capacitor winding element in which a separator paper is sandwiched and wound between a cathode foil and an anode foil, and a TCNQ salt that is meltable and has a conductivity that can be used as an electrolyte for a capacitor after being cooled and solidified, and is heated and melted. and a solid electrolyte obtained by melting and impregnating the TCNQ salt in the container into both negative and negative electrode foils of the capacitor winding element and the separator paper heated and carbonized at 400° C. or less, and solidified by cooling. A solid electrolytic capacitor whose container is used as it is as an outer container for the capacitor element.