JP4349558B2 - Solid electrolytic capacitor - Google Patents

Description

【００３４】
表１に示すように、従来の電荷移動錯塩単体（比較例１，２）の場合に比し、本発明の電荷移動錯塩混合物（実施例１〜４）は、電気伝導度が高く、該混合物を固体電解質として用いた固体電解コンデンサは、ＥＳＲが低く、高周波数で優れたコンデンサ特性を有していることがわかる。
【００３５】
【発明の効果】
本発明のＢＩＱ−ＴＣＮＱ錯塩とＨＩＱ−ＴＣＮＱ錯塩とからなる電荷移動錯塩混合物は、高電気伝導度であり、該電荷移動錯塩混合物を固体電解質として用いた、本発明の固体電解コンデンサは、ＥＳＲが低く、高周波数で優れたコンデンサ特性を有する。[0001]
[Industrial application fields]
The present invention relates to a charge transfer complex salt used in a solid electrolytic capacitor and a solid electrolytic capacitor having a high frequency low equivalent series resistance (hereinafter abbreviated as “ESR”) characteristic using the complex salt.
[0002]
[Prior art]
Conventionally, various solid electrolytic capacitors using a complex salt of 7,7 ′, 8,8′-tetracyanoquinodimethane (hereinafter abbreviated as “TCNQ”), which is an organic semiconductor, have been proposed as solid electrolytes. .
[0003]
A solid electrolytic capacitor is known in which an N-alkyl-substituted isoquinolinium-TCNQ complex salt is melted and liquefied on an anode foil, impregnated in a capacitor element, and then cooled and solidified to form a solid electrolyte (for example, , See Patent Document 1).
[0004]
Since the capacitor has excellent high frequency characteristics and the manufacturing process is relatively simple, an inexpensive capacitor can be supplied.
[0005]
However, in recent years, with the development of digital devices, switching regulators have increased in frequency and size and capacity have increased, and solid electrolytic capacitors are required to have higher frequency and lower ESR.
[0006]
Further, the ESR characteristic of the capacitor depends on the electric resistance of the solid electrolyte used, and a charge transfer complex salt having a high electric conductivity that satisfies the requirement for a high frequency and low ESR of the capacitor has been required.
[0007]
[Patent Document 1]
Japanese Examined Patent Publication No. 62-51491 (pages 2 and 3)
[0008]
[Problems to be solved by the invention]
The first object of the present invention is to provide a charge transfer complex salt having high electrical conductivity, and the second object is to provide excellent characteristics of high frequency and low ESR using the charge transfer complex salt as a solid electrolyte. A solid electrolytic capacitor is provided.
[0009]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that an Nn butylisoquinolinium-TCNQ complex salt (hereinafter abbreviated as “BIQ-TCNQ”) and an Nn heptylisoquinolinium-TCNQ complex salt (hereinafter referred to as “BIQ-TCNQ”). And abbreviated as “HIQ-TCNQ”) as a solid electrolyte, a solid electrolytic capacitor having excellent characteristics of high frequency and low ESR can be obtained. It came to complete.
[0010]
That is, the present invention is a charge transfer complex salt mixture comprising a BIQ-TCNQ complex salt and a HIQ-TCNQ complex salt, and a solid electrolytic capacitor comprising the mixture as a solid electrolyte.
[0011]
Hereinafter, the charge transfer complex salt mixture of the present invention will be described in detail.
[0012]
The BIQ-TCNQ complex salt and the HIQ-TCNQ complex salt of the present invention can be obtained by a known method as described on page 2 of JP-B-4-7086.
[0013]
The charge transfer complex salt mixture of the present invention can be obtained by adding HIQ-TCNQ complex salt in an amount of 1 to 50% by mass to BIQ-TCNQ complex salt and mixing them well. The content of the HIQ-TCNQ complex salt is preferably 5 to 40% by mass.
[0014]
When the HIQ-TCNQ complex salt is less than 1% by mass or more than 50% by mass, the electric conductivity is equal to or lower than that of the conventional TCNQ complex salt, which is inconvenient.
[0015]
In general, a TCNQ complex salt having an acceptor to donor molar ratio of 1: 1 or 2: 1 is known. In the TCNQ complex salt of the present invention, an acceptor TCNQ and a donor N-n are used. The molar ratio with butylisoquinolinium or Nn heptylisoquinolinium is 1.5-3: 1, preferably 1.8-2.7: 1. When the molar ratio is outside the range of 1.5 to 3: 1, the resulting charge transfer complex salt mixture is disadvantageous because of its low electrical conductivity.
[0016]
A solid electrolytic capacitor using the above charge transfer complex salt mixture as a solid electrolyte is produced according to the method described in Patent Document 1. Hereinafter, a manufacturing method thereof will be described.
[0017]
After etching and roughening the surface of the aluminum foil, which is a valve metal, the anode lead is connected by resistance welding, caulking, etc., and then electrolytically oxidized in an aqueous solution such as ammonium adipate, An anode foil having a dielectric oxide film formed on the surface of an aluminum foil by chemical conversion treatment is prepared. Between the opposing aluminum cathode foil with the cathode lead connected by resistance welding, caulking, etc. and the anode foil with the dielectric oxide film sandwiched between manila paper as a separator, wound into a cylindrical shape, and then heat treated Then, the capacitor paper is prepared by carbonizing the manila paper.
[0018]
Next, an appropriate amount of the charge transfer complex salt mixture prepared previously is packed in a separately prepared cylindrical aluminum capacitor case, and then heated to melt and liquefy the charge transfer complex salt mixture in the capacitor case. .
[0019]
Subsequently, after the capacitor element heated in advance is immersed in the molten and liquefied charge transfer complex salt mixture in the capacitor case, the capacitor element is immediately cooled, and the charge transfer complex salt mixture is solidified to form a solid electrolyte.
[0020]
Further, the capacitor case is sealed with an epoxy resin or the like, a voltage is applied, and aging is performed to complete the solid electrolytic capacitor of the present invention.
[0021]
The charge transfer complex salt mixture composed of the BIQ-TCNQ complex salt and the HIQ-TCNQ complex salt of the present invention has high electrical conductivity, and the solid electrolytic capacitor of the present invention using the charge transfer complex salt mixture as a solid electrolyte has a high frequency. Excellent capacitor characteristics with low ESR.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described based on examples. In addition, this invention is not limited at all by the Example.
[0023]
Example 1
After roughening the surface of the aluminum foil by etching, the anode lead is connected by caulking, and then subjected to chemical conversion treatment at a voltage of 10 V in a 10% by weight aqueous solution of ammonium adipate to oxidize the surface of the aluminum foil. An anode foil on which a film was formed was obtained. Next, a 50 μm-thick Manila paper is sandwiched as a separator between the opposing aluminum cathode foil to which the cathode lead is connected by resistance welding, and the anode foil, and then rolled into a cylindrical shape. The capacitor paper was prepared by carbonizing the Manila paper by heat treatment for a minute.
[0024]
Next, the HIQ-TCNQ complex salt in an amount of 5% by mass was added to the BIQ-TCNQ complex salt and mixed well to obtain the charge transfer complex salt mixture of the present invention.
[0025]
An appropriate amount of the above charge transfer complex salt mixture is packed in a bottomed cylindrical aluminum capacitor case (diameter 6 mmφ × height 7 mm), and then placed on a hot plate at a temperature of 300 ° C. for 20 seconds. The charge transfer complex salt mixture in the capacitor case was melted and liquefied.
[0026]
After the capacitor element preheated at a temperature of 300 ° C. is immersed in the melted and liquefied charge transfer complex salt mixture, the capacitor case is immediately cooled and solidified with water to form a conductive charge transfer complex salt mixture. A solid electrolyte layer was formed.
[0027]
Next, after sealing the capacitor case with an epoxy resin, a voltage of 10 V was applied and aged to complete a solid electrolytic capacitor having a rated voltage of 10 V and a rated capacitance of 22 μF.
[0028]
With respect to the completed capacitor, electrostatic capacity at 120 Hz (hereinafter abbreviated as “C”) and tan δ, and initial characteristics of ESR at 100 kHz were measured. The results are shown in Table 1.
[0029]
The charge transfer complex salt mixture was melted at a temperature of 200 ° C., cooled and solidified, and then pressure-molded at a pressure of 0.3 MPa to produce a disk-shaped pellet. The conductivity of the pellet was measured by the 4-terminal method. The results are shown in Table 1.
[0030]
Examples 2-4
In Example 1, a solid electrolytic capacitor was prepared in the same manner as in Example 1 using a charge transfer complex salt mixture of BIQ-TCNQ complex salt and HIQ-TCNQ complex salt having the composition shown in Table 1. Similarly, the initial characteristics of the solid electrolytic capacitor and the electrical conductivity of the pellet were measured. The results are shown in Table 1.
[0031]
Comparative Example 1
In Example 1, a solid electrolytic capacitor was produced in the same manner as in Example 1 except that the BIQ-TCNQ complex salt was used alone. In the same manner as in Example 1, the initial characteristics of the solid electrolytic capacitor and the electrical properties of the pellets were obtained. Conductivity was measured. The results are shown in Table 1.
[0032]
Comparative Example 2
In Example 1, a solid electrolytic capacitor was produced in the same manner as in Example 1 except that the HIQ-TCNQ complex salt was used alone. In the same manner as in Example 1, the initial characteristics of the solid electrolytic capacitor and the electrical properties of the pellets were obtained. Conductivity was measured. The results are shown in Table 1.
[0033]
[Table 1]

[0034]
As shown in Table 1, the charge transfer complex salt mixture (Examples 1 to 4) of the present invention has a higher electrical conductivity than the conventional charge transfer complex salt alone (Comparative Examples 1 and 2). It can be seen that a solid electrolytic capacitor using as a solid electrolyte has low ESR and excellent capacitor characteristics at a high frequency.
[0035]
【The invention's effect】
The charge transfer complex salt mixture composed of the BIQ-TCNQ complex salt and the HIQ-TCNQ complex salt of the present invention has high electrical conductivity. Low and excellent capacitor characteristics at high frequencies.

Claims (1)

Nnbutylisoquinolinium-7,7 ′, 8,8′-tetracyanoquinodimethane complex salt and Nnheptylisoquinolinium-7,7 ′, 8,8′-tetracyanoquinodi A charge transfer complex salt mixture comprising a methane complex salt, wherein the content of Nn heptylisoquinolinium-7,7 ′, 8,8′-tetracyanoquinodimethane complex salt is 5 to 40% by mass , A solid electrolytic capacitor characterized by being used as an electrolyte.