JPH02237010A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a highly efficient and reliable solid electrolytic capacitor by a method wherein acetophenoneisosemicarbazoletetracyanoquinodimethane complex salt, in which S-place is replaced with a hydrocarbon radical as an electrolyte, is used. CONSTITUTION:A solid electrolytic capacitor is fundamentally composed of a first electrode of a metal which function as a valve (for example, aluminum, tantal, titanium and the alloy of them) having an anodic oxide film on the surface formed by anodic oxidation, and a solid electrolyte consisting of TCNQ complex salt placed directly between the first and the second electrodes or by interposing a separator between them. Acetophenoneisosemicarbazole TCNQ complex salt is used as TCNQ complex salt, and the atom of acetophenoneisosemicarbazol, which is a cation, is replaced with alkyl radical having C1 to C18. When this acetophenoneisosemicarbazole TCNQ complex salt is used as the electrolyte of the solid electrolytic capacitor, a highly efficient solid electrolytic capacitor having excellent life characteristics can be obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides 7.7.8.8-
This article concerns a solid electrolytic capacitor whose solid electrolyte is an ionic radical salt consisting of tetracyanoquinodimethane. [Prior art and problems] 7.7.8.8-tetracyanoquinodimethane (hereinafter referred to as T
As a solid electrolytic capacitor using a radical salt consisting of CNQ (abbreviated as CNQ) as a solid electrolyte, for example, a TCNQ complex salt (Japanese Patent Application Laid-open No. 191414-1983), which has quinoline or isoquinoline as the electrolyte and TCNQ as the anion, is heated. It is well known that solid electrolytes are made by melting, cooling and solidifying. In addition, in the cation of these T C N Qll salts, the N position is substituted with an alkyl group selected from among 2 to 18 carbon atoms. TCN
The method of heating and melting the Ql salt and cooling and solidifying it is preferred because it allows etched aluminum foil or tantalum sintered body to be impregnated with the T C N Qm salt in a molten state. However, on the other hand, T
If the melting temperature of the CNQ complex salt is high or the melting time is long, the organic semiconductor TCN
Qfi salt decomposes. It transforms into an insulator. Another disadvantage is that the TCNQ complex crystallizes during cooling and solidification, making it impossible to obtain sufficient contact with the porous portion of the electrode foil. [Object of the invention] However, the present invention can eliminate the above-mentioned drawbacks, and specifically provides a novel organic semiconductor (new compound) that has a small specific resistance value and is thermally stable. The solid electrolyte is acetophenone isosemicarbazone TCNQ complex salt. This provides a solid electrolytic capacitor with high performance and reliability. [Summary of the Invention] The basic structure of the solid electrolytic capacitor according to the present invention is to use a valve metal (for example, aluminum, tantalum, titanium, or an alloy thereof) that has an anodized film on its surface by anodizing (chemical conversion). TCN is used as one electrode and directly or with a separator interposed between it and the second electrode (counter electrode).
It has a solid electrolyte consisting of Q complex salt. TCN
As mentioned above, the Q complex salt is acetophenone isosemicarbazone T C N Qil salt, and the S position of the cationic acid, acetophenone isosemicarbazone, has 1 carbon number.
Substituted by ~18 alkyl groups (including all isomers such as n-.iso-). Here, the structural formula of acetophenone isosemicarbazone TCNQm salt is as follows. Structural formula of S-substituted monoacetophenone isosemicarbazone TCNQ complex salt [11, where R represents an alkyl group of C1 to Cps. m
is a positive number (0.5
~1.5). Next, a method for synthesizing S-methyl-acetophenone isosemicarbazone TCNQ complex salt will be described. When 0.010 mol of acetophenone isosemicarbazone and 0-010 mol of methyl iodide are heated in a flask to about 40-45 ['C] in a water bath and stirred, a quaternization reaction occurs.6 This solution is 0.003 mol of the powder obtained by cooling (iodide-S-methyl-acetophenone isosemicarbazone) is dissolved in acetonitrile in a boiling state, and a boiling acetonitrile solution in which 0.003 mol of TCNQ complex salt is dissolved is prepared. Mix. Thereafter, by standing at 5° C. for about 10 hours, needle-shaped crystals of S-methyl-acetophenone isosemicarbazone TCNQ salt are obtained. The crystals are washed with a small amount of acetonitrile, then washed with ethanol until the washing solution is no longer colored, then washed with ether, dried, and applied to solid electrolytic capacitors. In addition, in this synthesis step, ethyl iodide, probyl iodide, etc. were used instead of methyl iodide.
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Get... As a typical example, the specific resistance value of S-methyl-acetophenone isosemicarbazone T C N Ql salt is 3.16 [Ω
・cml. The specific resistance value of S-ethyl-acetophenone isosemicorbazon T C N Ql salt is 4.45 [Ω
-cm]. The specific resistance value of N-n-pro and ruacetophenone isosemicarbazok TCNQII salt is 2.92 [Ω
・It was cml. [Example] Next, an example will be described in which the acetophenone isosemicorbazone T C N Q complex salt obtained as described above is applied to an electrolytic capacitor. S-Methyl-acetophenone isosemicarpazone T C
NCl! Dissolve the salt in acetonitrile to make a saturated solution. Next, immerse the capacitor element in this solution,
Thereafter, vacuum drying was performed at 50 to 60['C] to remove the solvent acetonitrile. This operation was repeated three times. The capacitor element uses an aluminum foil whose surface is etched approximately 10 times as much as the electrode, and an oxide film is formed on the surface by chemical conversion treatment. After impregnating with electrolyte, colloidal carbon is applied, then silver paste is applied, lead wires are soldered, and sheathing is performed to make the anode rated at 1.1 [μFl.
A solid electrolytic capacitor with a loss of 2.6% was obtained. Example of the solid electrolytic capacitor (rated 25 [V] ・1.0 [μFl]) according to the present invention obtained as described above,
N − was applied to the same capacitor element as in the example by thermal melting.
Table 1 shows a comparison of the life characteristics of a solid electrolytic capacitor impregnated with n-propyl-quinoline T C N Ql salt and a conventional example. In Table 1, the capacitance value and the tangent of the loss angle are the values at a frequency of 120 [Hz]. The leakage current is the value measured after 1 minute of applying the rated voltage (25 EV). Next, other embodiments of the present invention will be described.・S-Ethyl-acetophenone isosemicarpazone T
A compound of CNQ complex salt and a lactone compound, such as γ-butyrolactone (40 mgl) was packed into an aluminum case with a diameter of 5.0 mml, and heated for about 10 mg to 120 ['C].
It was heated in seconds and dissolved. A wound capacitor element, in which an anode foil and a cathode foil made of aluminum foil were wound with a separator layer in between, was immersed and crushed, and cooled approximately 12 seconds after immersion.
Note that prior to impregnation with the electrolyte, the capacitor element was heated to 120
The temperature was raised to ['c]. As a result, the rating l. 1.1 [uF] for the anode of o [uF],
A solid electrolytic capacitor with a loss of 2.9%1 was obtained. [Effect 1 The acetophenone isosemicarbazone TCNQ complex salt according to the present invention described above has higher thermal stability than the conventional quinoline TCNQ complex salt, and also provides an organic semiconductor with a low resistivity value. It is possible. Furthermore, when this acetophenone isosemicarbazone TCNQfi salt is used as an electrolyte in a solid electrolytic capacitor. As can be seen from Table 1, it is possible to provide a solid electrolytic capacitor with superior life characteristics compared to conventional examples.

Claims (2)

[Claims] (1) A solid electrolytic capacitor characterized in that acetophenone isosemicarbazone/7.7.8.8-tetracyanoquinodimethane complex salt substituted with a hydrocarbon group at the S position is used as an electrolyte. (2) A solid electrolytic capacitor according to claim (1), characterized in that the S position of the acetophenone isosemicarbazone is substituted with an alkyl group having 1 to 18 carbon atoms.