JPS6317515A - 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 an improvement in a solid electrolytic capacitor using a solid electrolyte.

[Background of the invention]

A solid electrolytic capacitor has a structure in which a solid electrolyte is attached to a dielectric film-forming metal such as aluminum having an anodized film. Conventionally, manganese dioxide has been used as the solid electrolyte in this type of capacitor.

However, when manganese dioxide is formed on an electrode, it is generally immersed in a manganese nitrate solution and then thermally decomposed, resulting in damage to the anodic oxide film and, in addition, the ability of manganese dioxide to repair the anodic oxide film is poor. There was a drawback.

In order to improve the above-mentioned drawbacks, it has been proposed to use an organic semiconductor, mainly a salt of 7,7,8,8-tetracyanoquinodimethane (TCNQ), as a solid electrolyte.

The TCNQ complex uses TCNQ as an acceptor and donor materials as quinoline (Qn) and tetrathiafulvalene (
TTF), N-methylphenazine (NMP), and tetraselenafulvalene (TSF) have been studied so far, and research on new donor materials is also being actively carried out, but there are still none that are fully satisfactory. Not obtained.

Especially in terms of heat resistance, TCN
All Q complexes have problems.

In other words, solid electrolytic capacitors are often exposed to heat such as soldering during the capacitor's structural processing process, and are placed near transformers in power supply circuits. Therefore, the electrolyte must be thermally stable, but all conventional TCNQ complexes have concerns in this respect.

[Purpose of the invention]

An object of the present invention is to provide a new and useful solid electrolytic capacitor that does not have any of the above-mentioned problems that solid electrolytic capacitors have.

(Summary of the Invention) The present invention provides an electrolyte that uses N- Alkyl-
T using 4-phenylpyridinium cation as donor material
This is a solid electrolytic capacitor characterized by the use of a CNQ complex.

Its characteristics as a donor material include a moderately small ionization potential, a stable ion with a wide π-electron system, and a high polarizability.

Satisfying all of these conditions is an important factor in molecular design, but it is extremely difficult to satisfy all of them. In addition, there is a problem in adhesion with electrodes when applying TCNQ26 bodies made of donor materials to electrolytic capacitors, and TCNQ, which has extremely fine crystal grains and has good compatibility with metal oxides, Complexes are preferred.

Furthermore, there is a need for a TCNQ complex whose electrical conductivity does not change much from low to high temperatures and does not decompose even at high temperatures.

The present inventors have conducted extensive research, discovered a new donor material for the TCNQ complex that can fully satisfy the above requirements, and have arrived at the present invention. That is, the present invention is characterized in that it uses an organic semiconductor that can be soldered to a printed circuit board at a sufficiently high temperature using a soldering flow after it has been commercialized.

The N-alkyl-4-phenylpyridinium TCNQ complex is represented, for example, as follows.

(In the formula, n represents an arbitrary number such as 0.5≦n≦2.) The N-alkyl-4-phenylpyridiny, umTCNQ complex has a relatively high melting point and decomposition point. . For example, N-isobutyl-4-phenylpyridinium T
The CNQ complex has a melting point of 250°C and a decomposition point of 2.
81”C, N-n-butylisoquinoline TCNQ
Complex melting start point 217.5°C, decomposition point 267.1'C
Both values are higher than that of . Thus, the N-alkyl-4-phenylpyridinium TCNQ complex is an extremely thermally stable complex.

Also, N-alkyl-4-phenylpyridinium TCN
Regarding conductivity, the Q complex can be sufficiently applied as a solid electrolyte for electrolytic capacitors. For example, N-
When 400 kg of isobutyl-4-phenylpyridinium TCNQ complex powder was pressurized and pelletized, the specific resistance value was 1 to 12 Ω·cm.

Complexes of TCNQ and N-alkyl-4-phenylpyridinium cations are stable up to high temperatures and therefore offer advantages in electrode bonding techniques. That is, it can be dissolved in a highly polar solvent with a high boiling point, and recrystallization occurs extremely quickly on the electrode surface during immersion and drying.

It can also be easily impregnated into the finely etched unevenness of the electrode surface of an aluminum electrolytic capacitor.

Although this is a problem due to conditions related to the crystallization rate, it goes without saying that the impregnated Asahi becomes better as the crystals become finer and denser.

Note that the anode electrode used in the solid electrolytic capacitor of the present invention is not limited to aluminum foil, and other valve metals can of course be used, and the same effect can be obtained even if a powder sintered electrode is used. Needless to say, you can obtain

The number of carbon atoms in the alkyl group attached to the N position of the 4-phenylpyridinium cation used in the solid electrolytic capacitor of the present invention is preferably 1 to IO; anything larger than that is unstable and is also disadvantageous from a cost perspective. There are many points.

Hereinafter, specific examples of the present invention will be described.

Example I N-isoamyl-4-phenylpyridinium TCNQ complex was supersaturated and dissolved in a nitrobenzene solution heated to 180°C. Next, an aluminum foil that had been etched 40 times was subjected to 50V chemical conversion to form an anode electrode. The electrode was immersed in the solution heated to 180°C, slowly pulled up, and dried at 230°C. This operation was repeated four times to complete the impregnation. Next, a capacitor sample (sample group A) was prepared by coating carbon as a cathode, coating silver paste thereon, and soldering lead wires.

For comparison, as a conventional example, N-n-butylisoquinoline TCNQ complex was dissolved in nitrobenzene heated to 180° C. in a supersaturated manner, and the same operation was repeated. The cathode and lead wires were attached in the same manner as described above to produce a capacitor sample (sample group B).

Furthermore, as a conventional example, using a saturated aqueous solution of manganese nitrate,
Immersion at 220° C. for 60 seconds and heat treatment were repeated six times.

Then, the cathode and lead wires were attached in the same manner as above to produce a capacitor sample (sample C).

Both samples are solid electrolytic capacitors with a rating of 25V and 47μF.

Table 1 shows the initial characteristics. The capacitance and tan δ are the values at room temperature, l 2011 z, and the leakage current is the value at room temperature, 1 minute after application of the rated voltage.

Table 1 Further, Table 2 shows the results of a high temperature load test for up to 2000 hours by applying a rated voltage in an atmosphere of 105°C.

Table 2 As is clear from Tables 1 and 2 above, it was demonstrated that the solid electrolytic capacitor of the present invention is thermally stable.

Example 2 The same electrode as in Example 1 was used as an anode foil, an aluminum foil etched about 10 times as much as the opposite electrode was used as a cathode, and electrolytic paper was used as a separator to form a wound capacitor (rated at 25W).
A device of 33 μF) was fabricated. The above element was subjected to flame treatment, impregnated with N-inbutyl-4-phenylpyridinium TCNQ complex, and packaged to prepare a group of capacitor samples.

For comparison, sample group E was prepared by similarly impregnating N-n-butylisoquinoline TCNQ complex.

Table 3 shows the initial characteristics and the characteristics after 1 minute of solder reflow at 250°C.

As is clear from the results in Table 3, the capacitance of the product using the N-n-butylisoquinoline TCNQ complex significantly decreased, while the tan δ increased significantly. This indicates that the complex was degraded by stress. In contrast, the N-isobutyl-4-phenylpyridinium TCNQ complex is extremely stable with little change in both capacitance and tan δ.

〔Effect of the invention〕

As described above, the solid electrolyte made of the TCNQ complex of N-alkyl-4-phenylpyridinium cation is extremely stable thermally and has good bonding properties between the electrode and the solid electrolyte, so the present invention uses this as an electrolyte. The solid electrolytic capacitor has remarkable effects in that its electrical characteristics are significantly improved and stabilized compared to conventional ones, and it has great industrial and practical value.

Patent Applicant: Wako Pure Chemical Industries, Ltd. Procedural Amendment October 9, 1985 1, Indication of Case 1988 Patent Application No. 162218 2, Name of Invention 541 Address 3, Domine-cho, Higashi-ku, Osaka-shi, Osaka Prefecture 10-chome Contact information Patent Law (Tokyo) 03-270-8571 Name Wako Pure Chemical Industries, Ltd. Sponsored 5 Column for detailed description of the invention in the specification to be amended.

6. Contents of amendment (3) “Structural treatment process” stated on page 3, line 6 of the specification has been changed to “
"Manufacturing process".

that's all

Claims (2)

[Claims] (1) N-alkyl-4-
TCN using phenylpyridinium cation as donor material
A solid electrolytic capacitor characterized by using a Q complex. (2) The solid electrolytic capacitor according to claim 1, wherein the alkyl group of the donor material has 1 to 10 carbon atoms.