JPS63200517A - 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 [Object of the Invention] (Industrial Application Field) The present invention relates to an electrolytic capacitor using a solid electrolyte made of an improved organic semiconductor.

(Prior art) In general, a dry foil electrolytic capacitor has a pair of anode and cathode foils made of, for example, high-purity aluminum foil connected to a pair of lead terminals also made of aluminum, and a spacer is placed between the pair of anode and cathode foils. A capacitor element is wound with a capacitor element interposed therebetween, impregnated with a driving electrolyte, and housed in a case, and the opening of the case is sealed or otherwise covered. However, since the driving electrolyte uses an organic carboxylic acid such as ammonium adipate in an organic solvent such as ethylene glycol, there is a limit to the improvement of tan δ characteristics, and the resistivity increases at low temperatures, resulting in low-temperature characteristics. There were issues that needed to be resolved in order to meet market demands, such as extremely poor performance and lack of reliability for use over a wide temperature range.

Therefore, in recent years, various devices using various TCNQ complexes instead of the driving electrolyte have been proposed, and some of them have been put into practical use.

Generally speaking, there are two methods for impregnating TCNQ forceps into a complexed capacitor element: solution impregnation method, dispersion impregnation method, and vacuum evaporation method, but the characteristics of the CNQ complex change under various conditions and it is an extremely difficult material to handle. , various measures have been taken for its use.

In particular, as conditions for the solid electrolyte, it is important that the resistance value itself, which affects tan δ as a capacitor characteristic and the equivalent series resistance, is small, and that the specific resistance value is stable even under temperature, especially high temperature.

Therefore, as a means for impregnating a wound element with a TCNQ complex, heating melting and liquefaction treatment is considered to be effective in industrially permeating the required amount of TCNQ complex into the inside of the element, according to conventionally proposed patent publications or technical literature.

Among them, those disclosed in JP-A-61-7618, JP-A-61-47642, etc.
Conventional method - A mixture of TCNQ nameplate with isoquinoline or bipyridine electron donor and TCNQ as electron acceptor, which has been formed into a film, and a complex compound or quinoline compound added is heated and melted and impregnated into the capacitor element. However, it is then solidified to form a solid electrolyte layer made of an organic semiconductor. That is, a compound is added to the CNQ complex, which does not have a melting point and decomposes and becomes insulating when heated, thereby making it possible to melt it by heating.

However, lactone compounds and quinoline compounds are considered to act as electron donors for TCNQ, which acts as an electron acceptor. In the TCNQ complex, the specific resistance varies greatly depending on the ratio of TCNQ, which is an electron donor and an electron acceptor.

For example, when the ratio of TCNQ as an electron donor to an electron acceptor is generally 1:2, the resistivity is the lowest, but when the ratio is 1:1, the resistivity becomes large, ranging from several + KO cm to several hundred to 0 cm.
In addition, in the case of 1:3, considering that the ratio becomes large from ΩCm to several tens of 0cm, mixing other compounds with the TCNQ complex deteriorates the TCNQ self-complex properties.

On the other hand, Japanese Patent Application Laid-open No. 17609/1983,
Publication No. 8-191414 or JP-A-59-63604
What is disclosed in the publication is generally understood, that is, TCNQ complexes are divided into those that have melting points and those that do not, depending on the type of substance that serves as an electron donor, and even if the skeleton structure is the same. For example, a quinoline or isoquinoline with a methyl group as a substituent has no melting point and decomposes when heated and becomes insulating.
Propyl group, ethyl group.

Focusing on the fact that those substituted with ethyl groups have a melting point, N-n-propyl (
Alternatively, a TCNQ complex consisting of quinoline, isoquinoline, etc. in which the N-position of N-position of N-isopropyl isoquinoline, N-ethylisoquinoline, and Nn-butylisoquinoline is substituted with a hydrocarbon group is used.

However, organic substances are generally weak against heat and the above TCN Q n
The body is also sensitive to heat, and according to the inventor's experimental results described later, for example, there is a problem that the resistivity value changes greatly when left at 105 degrees Celsius, and the 105 degrees Celsius lifespan of the electrolytic capacitor using the above TCNQ complex has a problem. The problem was that various properties in the test deteriorated significantly.

(Problems to be Solved by the Invention) As described above, the electrolytic capacitor having the above structure is TCN
There were problems with the specific resistance characteristics of the Q complex itself, and there was also a problem of specific resistance deterioration at high temperatures.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electrolytic capacitor using a TCNQ complex that has been developed based on various experimental results and is suitable for heat melt impregnation without deterioration of resistivity even at high temperatures. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The electrolytic capacitor of the present invention has a capacitor element wound with a spacer interposed between an anode foil and a cathode foil made of a valve metal, and heated and melted as a solid electrolyte. In the electrolytic capacitor impregnated with an organic semiconductor, the organic semiconductor is TCNQ of N-methyl-3-n propylimidazole.
It is characterized by the use of a complex.

(Function) According to the electrolytic capacitor having the above configuration, the organic semiconductor used as the electrolyte has little change in resistivity at high temperatures, so the high temperature life characteristics of the capacitor do not change much and reliability is improved.

(Examples) Examples of the present invention will be described in detail below. That is, as shown in FIG. 2, first, for example, the surface of an aluminum foil is roughened with an etching solution to enlarge the surface area, and then the anode foil 1 with an anodized film formed thereon and the surface of the aluminum foil are roughened with an etching solution in the same manner as described above. A negative Iti foil 2 with an expanded surface area is prepared. Next, a spacer 3 made of kraft paper or Manila paper is interposed between the anode foil 1 and the cathode foil 2, and an anode lead-out terminal 4 or a cathode lead-out terminal 5 is placed at an arbitrary point on the anode foil 1 and the cathode foil 2, respectively. is attached to obtain a wound capacitor element 6. Next, as shown in FIG.
The TCNQ complex of N-methyl-3-n propylimidazole is heated and melted to obtain a TCNQ complex of N-methyl-3-n propylimidazole molten 8I28, and then the capacitor is melted as shown in FIG. For example, the cord 6 is placed in the TCNQ button melt 8 in the case 7 in a preheated state, and the TC of the N-methyl-3-n propylimidazole is heated.
The NQ complex melt 8 is impregnated into the capacitor element 6, then cooled and solidified, and the opening of the case 7 is sealed with a sealing member 9.

In the electrolytic capacitor having the above configuration, the TCNQ complex of N-methyl-3-n propylimidazole as an organic semiconductor used as an electrolyte is resistant to the TCNQ complex itself under high temperature, as is clear from the experimental results shown below. Since the change in resistivity is small, it can greatly contribute to stabilizing the characteristics of electrolytic capacitors when left at high temperatures.

Next, the TCNQ complex (a) of N-methyl-3-n propylimidazole according to the present invention and the TCNQ complex (a) of N-butylisoquinoline, which is suitable for the above-mentioned heat melting treatment as a conventional reference example. b) As a result of measuring the change in resistivity at 105℃ using a method such as Nogi, the fourth
It was as shown in the figure. The measurement method is (a) and (b). 0.25g of each CNQ complex is placed in a mold with a diameter of 13# and a pressure of 10 tons is applied from above and below with a piston. Silver paste is applied to both sides of the molded body and dried. to form an electrode,
This resistance measurement value between the electrodes is used as the initial value, and then 10
It is left in a constant temperature bath at 5°C, and the resistance value is measured at regular intervals.

As is clear from FIG. 4, N-methyl-
TCNQ forceps of 3-n propylimidazole (complex is TCN of N-n-butylisoquinoline according to the conventional reference example)
It was demonstrated that the change in specific resistance was smaller than that of Q68 body (b).

In addition, in the conventional reference example mentioned above, there are other TCNQs of this type.
Since the results showing the same tendency as those in (b) above were obtained when complexing with an inscription, the description is omitted here.

-8 Next, an example of a comparison of the characteristics of electrolytic capacitors using each of the above TCNQ complexes in a high temperature load test at 105°C will be described.

Example A Anode foil Cathode foil spacer with roughened aluminum foil surface to increase surface area and then generate an anodic oxide film Cathode foil spacer with roughened aluminum foil surface to increase surface area Manila paper strip with a thickness of 50 μm CNQ complex N-methyl-3-n propylimidazole TCNQ complex CNQ complex heating melting strip 4! [An electrolytic capacitor with a rating of 25V-10μF that has a configuration with an epoxy resin seal and a case sealed with an epoxy resin seal.

Reference Example B An electrolytic capacitor with a rating of 25V-ioμF having the same configuration as the above example except for the TCNQ complex of TCNQ mirror N-n-butylisoquinoline.

Therefore, in the 105°C high temperature load test of the electrolytic capacitor IA of the embodiment according to the present invention and the electrolytic capacitor of the conventional reference example B, the capacitance change rate (%) versus time, tan δ versus time for 2 hours, and leakage versus time were determined. Current (μA
), the results are shown in FIGS. 5, 6, and 7.

As is clear from FIGS. 5 to 7, Example A is more stable in all characteristics than Reference Example B, and the stability with respect to capacitance change rate and tan δ change is particularly remarkable. I understand that.

[Effects of the Invention] According to the present invention, reliability is high in use under high temperatures;
An electrolytic capacitor with high practical value can be obtained.

[Brief explanation of the drawing]

1 to 3 relate to one embodiment of the present invention, in which FIG. 1 is a sectional view showing an electrolytic capacitor, FIG. 2 is an exploded perspective view showing a capacitor element constituting FIG. 1, and FIG. T on the case
An explanatory diagram of the manufacturing process with the CNQ complex added, Fig. 4 is a time-resistivity characteristic curve diagram, Fig. 5 is a time-capacitance population change rate characteristic curve diagram, and Fig. 6 is a time-tan δ characteristic curve diagram. , FIG. 7 is a time-leakage current characteristic curve diagram. 1... Anode foil 2... Cathode foil 6... Capacitor element 7... Case 8... TCNQ complex melt patent applicant Maru Time (h) Time (h) Figure 6 Time (1-1> Figure 5 Time (h) Figure 7

Claims (1)

[Claims] An electrolytic capacitor in which a capacitor element wound with a spacer interposed between an anode foil and a cathode foil made of a valve metal is impregnated with a heat-molten organic semiconductor as a solid electrolyte, wherein N-methyl-3 is used as the organic semiconductor. -n
An electrolytic capacitor characterized by using a TCNQ complex of propylimidazole.