JPH02239609A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain high performance and high reliability by using a thermally stable novel organic semiconductor having a small resistivity value as a solid electrolyte. CONSTITUTION:A valve action metal (such as aluminum, tantalum, titanium and these alloys), a surface of which has an anodic oxide film through anodizing (forming), is employed as a first electrode, and a solid electrolyte composed of a TCNQ complex salt is acquired directly or while interposing a separator between the first electrode and a second electrode (a counter electrode). 1- amino-3,3-dimethyl guanidinium TCNQ complex salt is used as the TCNQ complex salt. An organic semiconductor having thermal stability higher than quinoline TCNQ complex salt and also a resistivity value smaller than the quinoline TCNQ complex salt can be employed as the 1-amino-3,3-dimethyl guanidinium TCNQ complex salt. Accordingly, a solid electrolytic capacitor having lifetime characteristics more excellent than a conventional example is obtained.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides 7,7.8.8-
[Prior art and problems] 7.7.8.8-tetracyanoquinodimethane (hereinafter referred to as T
For example, as a solid electrolytic capacitor using an ionic radical salt consisting of CNQ (abbreviated as CNQ) as a solid electrolyte, for example, TCNQ# salt (JP 58-191414), which uses quinoline or inquinoline as a cation and TCNQ as an anionic acid, is heated and melted. However, it is well known that solid electrolytes are made by cooling and solidifying the material. In addition, these TCNQ! In the salt cation, the N-position is substituted with an alkyl group selected from 2 to 18 carbon atoms. The method of heating and melting TCNQ complex salt and solidifying it by cooling is to apply TCNQ to etched aluminum foil or tantalum sintered body.
This is preferable because it can be impregnated with m-salt in a molten state. However, on the other hand, if the melting temperature of the TCNQ complex salt is high or the melting time is long, the TCNQ complex salt, which is an organic semiconductor, will decompose and transform into an insulator. TCNQ during solidification
The disadvantage is that the I salt crystallizes and cannot make sufficient contact with the porous part of the electrode foil. [Objective of the Invention 1 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 present invention uses 1-amino-3,3-dimethylguanidium TCNQ1! salt as a solid electrolyte.Thereby, a solid electrolytic capacitor with high performance and high reliability is provided. [Summary of the invention] The basic structure of the solid electrolytic capacitor according to the present invention is that a valve metal (for example, aluminum, tantalum, titanium, and alloys thereof) having an anodized film on the surface by anodization (chemical conversion) is used as the first electrode, TCN directly or with a separator interposed between it and the second electrode (counter electrode)
It has a solid electrolyte consisting of Q1i salt. T.C.
As mentioned above, the NQ complex salt is 1-amino-3.3-
It is a dimethylguanidium T C N Q complex salt. Here, 1-amino-3,3-dimethylguanidium TCN
The structural formula of Q complex salt is as follows. 1-amino-
3. 3-Dimethylguanidium T CNQ! Structural formula of the salt [11, m is a neutral 7,7.
It means a positive number (0.5 to 1.5) corresponding to the number of moles of 8.8-tetracyanoquinodimethane. Next, 1-amino-3.3-dimethylguanidium T
The method for synthesizing C N Qll salt will be described. 0.01
0.0 moles of l,l-dimethylthiourea in ethylene glycol dimethyl ether solvent. 1,1-dimethyl-S-methylisothiourea hydroiodide was obtained by reacting with 1 mole of methyl iodide. This 0. Ol
molar l. Synthesis of 1-amino-3,3-dimethylguanidine-hydriodide by reacting l-dimethyl-S-methylisothiurea hydroiodide with 0.012 moles of hydrazine hydride in an ethanol solvent. did. 0,0025 mol of this 1-amino-3.3-dimethylguanidine-hydriodide was dissolved in acetonitrile in a boiling state, and 0.0025 mol of T C N Q
Mix with the boiling acetonitrile solution containing the m-salt. After that, by leaving it at 5°C for about 10 hours,
1-Amino-3,3-dimethylguanidium TCN
Needle-shaped crystals of Qil 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. 1-amino-3.3
-Dimethylguanidium TCNQ! The specific resistance value of salt is 2.
It was 38 [Ω・cm]. [Example] Next, an example will be described in which the 1-amino-3,3-dimethylguanidium TCNQm salt obtained as described above was applied to an electrolytic capacitor. Dissolve 1-amino-3,3-dimethylguanidium TCNQIi salt in acetonitrile. Make it a saturated solution. Next, the capacitor element was immersed in this solution, and then vacuum dried at 50 to 60['C] to scatter the acetonitrile solvent. This operation was repeated three times. The capacitor element uses aluminum foil whose surface is etched approximately 10 times as much as the electrode.
Furthermore, an oxide film is formed on the surface through chemical conversion treatment. After electrolyte impregnation, apply colloidal carbon, then apply silver paste, and solder the lead wires.
By packaging, the rating is 1.0 [μFl for an anode. 1 [μFl. loss 2.4

A solid electrolytic capacitor of [%] was obtained. The solid electrolytic capacitor (rated 25 [V] - 1.0 [μF]) 77) according to the present invention obtained as described above and the capacitor element similar to the example were heated by thermal melting.
Table 1 shows a comparison of the life characteristics of a solid electrolytic capacitor impregnated with N-n-probyl-quinoline T C N Qm 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 [Hzl]. The leakage current is the value measured after 1 minute of applying the rated voltage (25 [V]). Next, other embodiments of the present invention will be described. ■-Amino-3,3-dimethylguanidium TCNQ
Complex salt and lactone compound, such as γ-butyrolactone compound 40 [mgl in diameter 5. It was filled into an aluminum case of 0 [mm] and heated to 180 ["c] at a rate of about 10 to melt it. An anode foil and a cathode foil made of aluminum foil were wound in the aluminum case through a separator. The capacitor element was immersed and cooled approximately 12 seconds after immersion.Before impregnating with the electrolyte, the capacitor element was heated to 180 ['
The temperature was raised to [c]. This results in a rating of 1
．． 1 for an anode of 0 [μF]. A solid electrolytic capacitor with a loss of 2.0E%1 was obtained. [effect]

Claims (1)

[Claims] (1) A solid electrolytic capacitor characterized in that a 1-amino-3,3-dimethylguanidium/7,7,8,8-tetracyanoquinodimethane complex salt is used as an electrolyte.