JPH0770247B2 - Heat resistant charge transfer complex - Google Patents

Description

TECHNICAL FIELD The present invention relates to a charge transfer complex having excellent conductivity and heat resistance. The present invention also relates to a solid electrolytic capacitor using the above charge transfer complex.

(Prior Art) In recent years, with the development of digital equipment, there is an increasing demand for a large-capacity capacitor having a low impedance in a high frequency region and excellent high frequency characteristics.

Conventionally, films, mica, and ceramic capacitors have been used as capacitors having excellent high-frequency characteristics, but when the capacity is increased, the shape becomes larger and the cost becomes higher.

Further, electrolytic capacitors as large-capacity capacitors include electrolytic solution type and solid electrolyte type using manganese dioxide.
The former has poor capacitor characteristics over time, and the high frequency characteristics are also poor because the electrolyte is ionic conductive. The latter has high impedance or loss in the high frequency region because the oxide film is easily damaged during the thermal decomposition of manganese nitrate.

In order to solve the above drawbacks of conventional capacitors, 7,7,
An electrolytic capacitor has been proposed which uses 8,8-tetracyanoquinodimethane (hereinafter abbreviated as TCNQ) as an acceptor and a charge transfer complex composed of a combination with various donors as a solid electrolyte. The donor of the proposed TCNQ charge transfer complex is N
-N-hexylquinoline, N-ethylisoquinoline, or Nn-butylisoquinoline (JP-A-58-1914)
4), N-n-amylisoquinoline, or N-isoamylisoquinoline (JP-A-62-116552).

On the other hand, the miniaturization and thinning of electronic devices, and further resource saving have made it necessary to make electronic components into chips.
In this chip component, a land which is a circuit pattern and a terminal of the chip component are soldered by a reflow soldering method or a dip soldering method. Therefore, the TCNQ charge transfer complex is also required to have a heat resistance of 230 ° C or higher.

(Problems to be solved by the invention) However, the TCNQ charge transfer complex proposed up to now is 23
When it is melted by heat at a temperature lower than 0 ° C and left in this state for a certain period of time or longer, oxidative decomposition occurs. For this reason, the loss of the capacitor characteristics becomes large especially at the time of soldering, the conductivity also decreases, and the high frequency characteristics deteriorate.

An object of the present invention is to solve the above problems, and firstly to provide a charge transfer complex having excellent heat resistance and conductivity, and secondly to use the charge transfer complex as an electrolyte of a capacitor. Another object of the present invention is to provide an electrolytic capacitor having excellent characteristics that can withstand soldering.

(Means for Solving the Problems) As a result of intensive studies for the above purpose, the present inventors have found that 3-phenylpyridine in which the N-position is substituted with an alkyl group having 2 to 6 carbons is a donor and TCNQ is an acceptor. The present inventors have completed the present invention by finding that the charge transfer complex described above solves the above problems, and that a capacitor using these complexes as an electrolyte is a solid electrolytic capacitor having particularly excellent heat resistance.

Next, a method for synthesizing the complex of the present invention will be described. The corresponding alkyl iodide having 2 to 6 carbon atoms and 3-phenylpyridine, which is the donor matrix, are reacted in an alcoholic solvent to introduce the iodide corresponding to the N-position to obtain a donor, and the donor and TCNQ. When the and are reacted in acetonitrile, the heat resistant charge transfer complex of the present invention is obtained.

Generally, a charge transfer complex having a molar ratio of acceptor to donor of 1 or 2 is known, and the molar ratio of the complex of the present invention is 1.5 to 3, preferably 1.8 to 2.2.

Heat-melting the charge transfer complex thus obtained,
It is impregnated between both electrodes of an element composed of an anode body and a cathode body and then cooled to attach a complex to form a capacitor element, which is incorporated into a solid electrolytic capacitor.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 16.0 g of ethyl iodide, 15.5 g of 3-phenylpyridine
And 50 ml of ethyl alcohol was placed in a flask equipped with a reflux condenser and a stirrer and reacted under reflux for 3 hours. After completion of the reaction, ethyl alcohol was distilled off under reduced pressure, and the solid residue was washed twice with 50 ml of ethyl ether to obtain 27.3 g of N-ethyl-3-phenylpyridinium iodide. Then, 150 ml of acetonitrile and 2.04 g of TCNQ were placed in a flask equipped with a reflux condenser and a stirrer and heated, and N-ethyl-3-phenylpyridinium iodide 2.
50 ml of an acetoniryl solution in which 33 g was dissolved was added dropwise, and the mixture was refluxed for 30 minutes. After cooling the reaction solution, the precipitated crystals were filtered off and washed twice with 50 ml of methyl alcohol to obtain 2.57 g of N-ethyl 3-phenylpyridinium.TCNQ complex. The results of elemental analysis of the complex are shown below.

Elemental analysis value C ₃₇ H ₂₃ N ₉ Calculated value: C%: 74.86, H%: 3.91, N%: 21.23 Measured value: C%: 74.67, H%: 3.98, N%: 21.35 Also, a thermal analyzer was used. Results of differential thermal analysis (Fig. 1),
The melting point of the complex was 235 ° C, and the exothermic decomposition point was 255 ° C. The infrared absorption spectrum of this complex is shown in FIG.

Next, 60 mg of the complex was filled in an aluminum case having a diameter of 6.3 mm,
The winding type aluminum electrolytic capacitor unit was immersed in heat and melted, and immediately cooled to obtain a capacitor. As the capacitor unit, an aluminum surface was subjected to chemical conversion treatment to form an oxide film, and the capacitor unit was preheated before immersion. The characteristics of the obtained capacitor are shown in the column before the heat resistance test in Table 2. Next, this capacitor was put together with the case in a solder bath at 230 ° C. for 30 seconds and left at room temperature, and the capacitor characteristics were measured again. This value is shown in the column after the heat resistance test in Table 2.

Examples 2 to 7 Instead of ethyl iodide, equimolar amounts of n-propyl iodide, iso-propyl iodide, n
-Butyl iodide, n-amyl iodide, iso
-The TCNQ charge transfer complex was synthesized according to Example 1 except that amyl iodide and n-hexyl iodide were used, and the melting point and exothermic decomposition point were measured from the results of differential thermal analysis using a thermal analyzer. The results are shown in Table 1. The corresponding differential thermal analysis data and infrared absorption spectrum are shown in FIGS. 2 and 11 for n-propyl, and FIGS. 3 and 12 for iso-propyl.
n-butyl is shown in FIGS. 4 and 13, n-amyl is shown in FIGS. 5 and 14, iso-amyl is shown in FIGS. 6 and 15, and n-hexyl is shown in FIGS. 7 and 16, respectively. It was

Then, a capacitor was obtained according to Example 1, and the capacitor characteristics before and after the heat resistance test were measured. These values are shown in Table 2.

Comparative Example 1 n-Butyl iodide 1 instead of ethyl iodide
8.4 g of quinoline instead of 3-phenylpyridine
N-n according to Example 1 except that 12.9 g was used respectively.
-Butylquinolinium TCNQ complex was synthesized, and the melting point and exothermic decomposition point were measured from the differential thermal analysis data (Fig. 8) using a thermal analyzer, and the results are shown in Table 1. The infrared absorption spectrum is shown in FIG.

Then, a capacitor was obtained according to Example 1, and the capacitor characteristics before and after the heat resistance test were measured. These values are shown in Table 2.

Comparative Example 2 Instead of ethyl iodide, iso-amyl iodide 1
According to Example 1, except that 9.8 g was used and 4-phenylpyridine was used instead of 3-phenylpyridine.
The TCNQ complex was synthesized, and the melting point and exothermic decomposition point were measured from the differential thermal analysis data (Fig. 9) using a thermal analysis device, and the results are
Shown in the table. The infrared absorption spectrum is shown in FIG.

Then, a capacitor was obtained according to Example 1, and the capacitor characteristics before and after the heat resistance test were measured. These values are shown in Table 2.

From Table 1, the complexes shown in the examples have a uniform melting point of 230 ° C.
It was found that the thermal stability was extremely excellent because it was higher than the above and had a higher exothermic decomposition point than the N-n-butylquinolinium complex described in Comparative Example 1 or the conventionally known complex.

Cap in Table 2 is the capacitance at 20 ° C and 120Hz (μ
F), tan δ is dielectric loss tangent (%), ES at 20 ° C, 120Hz
R is the equivalent series resistance (mΩ) at 20 ° C and 100kHz. ΔC / C is the rate of change (%) in capacitance at 85 ° C. with respect to 20 ° C.

From Table 2, the capacitors made with the complex using 3-phenylpyridinium have improved tan δ, ESR, etc. compared to the capacitors made with the complex using the heat-resistant 4-phenylpyridinium which is its isomer. It was found that the characteristics after the capacitors made of the complexes shown in the examples were put in the solder bath did not change much compared to the initial characteristics, and that the capacitors exhibited excellent characteristics.

(Effect of the Invention) 3 in which the N-position of the present invention is substituted with an alkyl group having 2 to 6 carbon atoms
-A charge transfer complex consisting of phenylpyridine and TCNQ
It has a melting point of 0 ° C or higher, and its thermal stability is remarkably improved.
In addition, the solid electrolytic capacitor using the complex of the present invention as an electrolyte exhibits heat resistance that can withstand soldering, and therefore has a small loss, a low conductivity, and a high frequency characteristic.

[Brief description of drawings]

1 to 7 and 10 to 16 show a first embodiment of the present invention.
8 is a differential thermal analysis data and infrared absorption spectra of the complexes of Nos. 7 to 7, and FIGS. 8 and 17 show the results of Comparative Example 1, and FIGS. 9 and 18 show the results of Comparative Thermal Analysis of the complexes of Comparative Example 2. It is data and an infrared absorption spectrum.

Claims (2)

[Claims] 1. A heat-resistant charge transfer complex which uses 3-phenylpyridine in which the N-position is substituted with an alkyl group having 2 to 6 carbon atoms as a donor and 7,7,8,8-tetracyanoquinodimethane as an acceptor. 2. A heat-resistant charge transfer complex which uses 3-phenylpyridine having an N-position substituted by an alkyl group having 2 to 6 carbon atoms as a donor and 7,7,8,8-tetracyanoquinodimethane as an acceptor. A heat-resistant solid electrolytic capacitor with an electrolyte.