JPS63127525A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to 7,7,8,8-tetracyanoquinodimethane (
The present invention relates to a method for manufacturing a solid electrolytic capacitor using an organic semiconductor made of a complex salt (TCNQ) as a solid electrolyte.

Background Art Solid electrolytic capacitors using TCNQ complex salt as a solid electrolyte are disclosed in JP-A-56-58818 and JP-A-56-116861. The capacitor is manufactured by heating and melting N-alkylisoquinolium (TCNQ)2, in which the N-position is substituted with an alkyl group, as an electrolyte, thereby forming a first electrode having an oxide film and a second electrode facing it. Impregnation treatment is performed on the space having the separator between the two electrodes. After the impregnation, a rapid cooling treatment is performed using a solvent or the like as disclosed in Japanese Patent Application Laid-Open No. 58-175819. Finally, the exterior is treated using aluminum or epoxy resin.

Problems to be Solved by the Invention However, compared to the case where an aqueous solution is used as the electrolyte, the TCNQ salt has a problem in that the capacity achievement rate is lower. If the aqueous solution is 100%, the TCNQ salt is about 70 to 80%. Furthermore, when left at high temperatures or temporarily exposed to high temperatures for soldering, leakage current increases and capacity decreases.

An object of the present invention is to prevent deterioration of capacitor characteristics such as an increase in leakage current and a decrease in capacitance due to high temperature storage, etc., and to improve capacitor reliability.

Means for Solving the Problems The present invention achieves the above object, and its technical means is to thermally melt a TCNQ complex salt to form a first electrode having an oxide film on its surface, and a first electrode having an oxide film on its surface. The manufacturing method involves impregnating a capacitor unit composed of a second electrode and the like provided facing the capacitor, and then immersing the capacitor unit in a liquid of a five-membered heterocyclic compound that thermally polymerizes with the TCNQ complex salt to forcibly cool it.

Function: After melting TCNQ salt and impregnating it into the capacitor unit,
TCNQ is used as a refrigerant for rapid cooling.
The above problems are solved by using a liquid of a five-membered heterocyclic compound that thermally polymerizes with a salt.

Examples of five-membered heterocyclic compounds include pyrrole and thiophene.

Selected from derivatives of furan. N- as TCNQ complex salt
It is preferable to use alkylisoquinolium (TCNQ) 2 and to use a pyrrole dielectric as the liquid of the five-membered heterocyclic ring to be cooled.

In the case of TCNQ salt, the capacity achievement rate is not 100% because the dielectric film is usually etched into micropores to increase the surface area, but the hot melt of TCNQ salt completely fills the micropores. This is because it is not impregnated. Water and organic solvent molecules are well impregnated into the micropores, achieving 100% capacity. Cooling using a solvent such as that disclosed in JP-A-58-175819 does have a cooling effect, but it does not improve the capacity achievement rate. However, the cooling effect is excellent if water, methanol, ethanol, acetone, etc. are used for cooling. As for capacitor characteristics, if refrigerant molecules remain in the condenser unit immediately after cooling, the capacity will apparently show a value of 90% or more in terms of capacity achievement rate, but since the refrigerant molecules are highly volatile, The capacitance value gradually decreased to 80
% capacity. Therefore, in the present invention, T
Using CNQ salt and a five-membered heterocyclic compound such as pyrrole, thiophene, or furan, which undergoes a thermal polymerization reaction, as a coolant, the liquid molecules that have penetrated into the micropores of the dielectric film are heat-treated to perform a polymerization reaction. This makes it possible to maintain a high capacitance value. Furthermore, when mechanical strain is applied to the aluminum oxide film, defects readily occur, resulting in an increase in leakage current. Also, at high temperatures (for example, 105 to 11
5° C.) or temporarily exposed to high temperatures (approximately 200 to 230° C.) for soldering, the leakage current not only increases, but also the capacitance decreases. This is thought to be due to deterioration in the adhesion between the TCNQ salt and the oxide film, which is a dielectric film. By infiltrating the five-membered heterocyclic compound mentioned above and performing a polymerization reaction by heat treatment, the adhesion between the TCNQ salt and the dielectric film is improved, and the resistance to mechanical strain is also increased. , long-term exposure to high temperatures and soldering can eliminate deterioration of capacitance and leakage current characteristics due to thermal shock.

Example Examples of the present invention will be discussed in detail below.

The TCNQ salt is N-isoamylisoquinolium (T
CNQ)2 was used. The structure of the capacitor used here is that aluminum, which has an oxide film on its surface through anodization, is used as the first electrode, aluminum is used as the second electrode, and a separator is placed between the first and second electrodes. It is a winding type. The unit used here has a rating of 100μ
It is for F116■. After crushing the TCNQ salt that will become the electrolyte into a fine powder, it is packed in an aluminum can case (10H diameter).
1 height 11B) was filled with the required amount and melted on a hot plate at 270° C. to form a liquid. A winding unit of an aluminum electrolytic capacitor was immersed in this to sufficiently impregnate it, and then rapidly cooled using pyrrole as a refrigerant. In addition, liquid N2 was used as a refrigerant for comparison.

After the liquid N2 has cooled the condenser unit, it is mostly vaporized inside the unit and does not remain. These units are housed in an aluminum can case (diameter 8ff, height 10ff)
), and the top was sealed with epoxy resin. Heat treatment at 85℃~120℃ to harden the epoxy resin
Regardless of the time taken, the pyrrole remaining in the unit during this treatment undergoes a sufficient thermal polymerization reaction. The table below shows a comparison of properties when liquid N2 and pyrrole are used as refrigerants.

Comparison of properties was made after 10,008 hours of standing at 105°C. The number of characteristics is the average value of 10 samples.

Table Capacitor characteristics (initial value of leakage current is 5μA in both cases)
When subjected to 15 s C treatment in a solder bath at 230° C., there was no change in capacity. The increase in leakage current showed similar results to the above table.

Similar effects were obtained when thiophene or furan was used as a refrigerant instead of pyrrole.

Effects of the Invention In short, the present invention provides a solid electrolytic capacitor using TCNQ salt, which uses a five-membered heterocyclic compound such as a derivative of pyrrole, thiophene, or furan as a refrigerant used for rapid cooling after being thermally melted and impregnated. This has the advantage of being able to prevent deterioration of capacitor characteristics such as an increase in leakage current and a decrease in capacitance, and improve the reliability of capacitor characteristics.

Claims (2)

[Claims] (1) a first electrode having an oxide film on its surface;
After impregnating heat-molten 7,7,8,8-tetracyanoquinodimethane (TCNQ) complex salt between and around the electrode and the second electrode provided oppositely, pyrrole, thiophene, and furan are added. A method for manufacturing a solid electrolytic capacitor, which comprises forcibly cooling it by immersing it in a liquid of a five-membered heterocyclic compound containing at least one of the following. (2) The method for manufacturing a solid electrolytic capacitor according to claim 1, in which N-alkylisoquinolium (TCNQ)_2 is used as the TCNQ complex salt and a pyrrole derivative is used as the cooling five-membered heterocyclic liquid.