JP2000030985A - Polarizable aluminum electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polalizable aluminum electrolytic capacitor which has no leakage of the electrolyte for driving even if an active chemical is used for the electrolyte. SOLUTION: This polarizable aluminum electrolytic capacitor is constituted of a capacitor element 2 made by winding an anode foil and a cathode foil with electrolytic paper between, a rubber sealing body 5 with its terminal insertion holes 51, 52 fit with aluminum round bars 31, 41 of an anode lead terminal 3 and a cathode lead terminal 4 extracted from the anode foil and the cathode foil respectively, and an aluminum case 6 which seals the capacitor element 2 impregnated with the nonaqueous electrolyte for driving including quarternary ammonium salt or imidazolinium salt, together with the sealing body 5. As the material of the rubber sealing body 5, butyl rubber coated with silicon for alkali resistant coating is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum electrolytic capacitor. More specifically, the present invention relates to a technique for preventing a driving electrolyte from leaking from an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art FIGS. 1 and 2 are an explanatory view showing components of an aluminum electrolytic capacitor and a sectional view of the aluminum electrolytic capacitor, respectively. As shown in FIGS. 1 and 2, a small aluminum electrolytic capacitor generally includes a capacitor element 2 wound between an anode foil and a cathode foil via electrolytic paper, and an anode foil and a cathode foil of the capacitor element 2. The rubber sealing member 5 in which the aluminum round bar portions 31 and 41 of the extracted anode lead terminal 3 and cathode lead terminal 4 are fitted in the terminal insertion holes 51 and 52, respectively, and a capacitor impregnated with a driving electrolyte. And an aluminum case 6 for sealing the element 2 together with the rubber sealing body 5.

[0003] In recent years, aluminum electrolytic capacitors have also been required to have low loss and low impedance characteristics in order to cope with the development of digital circuits and the like. An important technique for meeting these demands is mainly to reduce the specific resistance of the driving electrolyte impregnated in the capacitor element. The driving electrolyte satisfying this requirement includes γ-butyrolactone alone or a mixed solvent of γ-butyrolactone as a main solvent and ethylene glycol mixed therein, such as a quaternary ammonium salt of o-phthalic acid or maleic acid. Is used as a solute.

[0004] Such a driving electrolyte solution using an organic solvent is drastically lost after passing through a rubber sealing body in a high-temperature atmosphere, and such a loss causes remarkable deterioration of capacitor characteristics. Therefore, when such a driving electrolyte is used, various design considerations have been made in terms of airtightness, such as using butyl rubber having low gas permeability as a rubber sealing member.

[0005]

However, in the aluminum electrolytic capacitor using the above-mentioned driving electrolytic solution, a new problem not pointed out in the conventional aluminum electrolytic capacitor has been pointed out. That is, when the aluminum electrolytic capacitor is used for a long time in a loaded state or left for a long time in a no-load state, the driving electrolyte leaks from the terminal insertion hole on the cathode side of the rubber sealing body and leaks. This is a problem that the wiring pattern causes a short circuit on the circuit board due to the driving electrolyte solution.

Accordingly, an object of the present invention is to realize a polar aluminum electrolytic capacitor which does not cause leakage of the electrolytic solution even when the above-mentioned active chemical is used for the driving electrolytic solution.

[0007]

Means for Solving the Problems The present invention is based on new findings obtained from various studies conducted to prevent the driving electrolyte from leaking from the terminal insertion hole on the cathode side of the rubber sealing body. The present invention is based on an aluminum round bar portion of a lead terminal that is in contact with a terminal insertion portion on the cathode side of a rubber sealing body and an electrode potential difference of a cathode foil connected to the terminal. That is, in the conventional polar aluminum electrolytic capacitor, the cathode foil has a lower electrode potential than the aluminum round bar portion of the lead terminal connected thereto,
A local battery is formed by the cathode foil and the aluminum round bar. Therefore, in the conventional polar aluminum electrolytic capacitor, the electrode reaction at the round bar portion of the lead terminal on the cathode side causes alkalinization of the driving electrolyte near the round bar portion. As a result, alkali deterioration of the rubber sealing body in contact with the driving electrolyte near the round bar portion of the lead terminal on the cathode side, that is, the rubber elasticity of the inner surface of the terminal insertion hole is reduced, and the driving electrolyte from this portion is reduced. Liquid leakage will occur.

Based on such findings, the present invention is characterized in that the leakage of the driving electrolyte is prevented by improving the alkali resistance itself of the rubber sealing body. That is, in the present invention, a capacitor element wound between an anode foil and a cathode foil via electrolytic paper, and aluminum of an anode lead terminal and a cathode lead terminal drawn out from the anode foil and the cathode foil of the capacitor element. And a capacitor element impregnated with a non-aqueous electrolyte for driving containing at least one of a quaternary ammonium salt and an imidazolinium salt. A polar aluminum electrolytic capacitor having a case sealed with the rubber sealing body,
The rubber sealing body is characterized in that at least the inside of the terminal insertion hole on the cathode side is coated with an alkali resistant coating.

In the present invention, the alkali-resistant coating is, for example, a silicon coating on the entire surface of the sealing rubber body. The non-aqueous driving electrolyte referred to in the specification of the present application is different from an ethylene glycol-water driving electrolyte containing 10% or more of water, in which no or no water is added. % Of the driving electrolyte.

In the present invention, since the alkali-resistant coating is applied to at least the terminal insertion hole on the cathode side of the rubber sealing body or the entire surface of the rubber sealing body, the rubber sealing body is provided near the round bar portion of the lead terminal on the cathode side. Even if the drive electrolyte in contact with the body is slightly alkalized, the rubber sealing body does not deteriorate. Therefore, leakage of the driving electrolyte can be prevented.

[0011]

Embodiments of the present invention will be described.
The structure of the aluminum electrolytic capacitor used here is as described with reference to FIG. 1 and FIG. Example 1 First, 15% by weight of a phthalic acid salt of tetraethylammonium as a main solute was blended with a solvent containing γ-butyrolactone as a main component to prepare a driving electrolyte.
Next, using this driving electrolyte, rated voltage 16 V, capacitance 330 μF, case size 10 mm, length 12.5
mm electrolytic capacitor is manufactured.

As the rubber sealing member according to the embodiment used here, after molding the rubber sealing member made of butyl rubber is completed.
% Silicon solution, a 5% silicon solution, and a 10% silicon solution. In the rubber sealing body subjected to such a treatment, a silicon film is formed on the entire surface as an alkali-resistant coating layer. Therefore, in the rubber sealing body, the anti-alkaline coating layer (silicon film) is formed at least on the inner surface of the terminal insertion hole on the cathode side. In the conventional example, a rubber sealing body not subjected to such treatment was used.

Using each of these materials, 500 electrolytic capacitors were manufactured and subjected to an aging treatment. A rated voltage was applied in a high-temperature and high-humidity atmosphere at a temperature of 85 ° C. and a humidity of 85%. After the test, the leakage of the driving electrolyte was confirmed for each capacitor sample after the test. The results are shown in Tables 1 and 2.

[0014]

[Table 1]

[0015]

[Table 2] As is clear from Tables 1 and 2, it was found that the aluminum electrolytic capacitor using butyl rubber coated with an alkali-resistant coating as the rubber sealing member did not cause leakage of the driving electrolyte, and high reliability was obtained. . In addition,
In place of tetraethylammonium phthalate, tetraethylammonium maleate, tetramethylammonium phthalate or other quaternary ammonium salts such as maleate and the like, in the evaluation performed in the driving electrolyte, Again, it was confirmed that no leakage of the driving electrolyte occurred in the aluminum electrolytic capacitor using butyl rubber coated with an alkali-resistant coating as the rubber sealing member. Example 2 In a solvent containing γ-butyrolactone as a main component, a phthalate of imidazolinium was used as a main solute to form
By weight, a driving electrolyte was prepared. Next, using this driving electrolyte, a rated voltage of 16 V and a capacitance of 330 μm
F. An electrolytic capacitor having a case size of 10 mm and a length of 12.5 mm is manufactured.

As the rubber sealing member according to the embodiment used here, after molding the rubber sealing member made of butyl rubber, 2
% Silicon solution, a 5% silicon solution, and a 10% silicon solution. In the rubber sealing body subjected to such a treatment, a silicon film is formed as an anti-alkaline coating layer on the entire surface. Therefore, in the rubber sealing body, the anti-alkaline coating layer (silicon film) is formed at least on the inner surface of the terminal insertion hole on the cathode side. In the conventional example, a rubber sealing body not subjected to such treatment was used.

After 500 electrolytic capacitors were manufactured using these materials and subjected to aging treatment, a rated voltage was applied in a high-temperature and high-humidity atmosphere at a temperature of 85 ° C. and a humidity of 85%, and a no-load test was performed for 7000 hours. After the test, the leakage of the driving electrolyte was confirmed for each capacitor sample after the test. The results are shown in Tables 3 and 4.

[0018]

[Table 3]

[0019]

[Table 4] As is evident from Tables 3 and 4, it was found that the aluminum electrolytic capacitor using butyl rubber coated with an alkali-resistant coating as the rubber sealing member did not cause leakage of the driving electrolyte and high reliability was obtained. . [Other Examples] In the above embodiment, a silicon film is formed as an example of the alkali-resistant coating. However, any other coating may be used as long as the rubber sealing body can be protected from alkali.

[0020]

As described above, in the aluminum electrolytic capacitor according to the present invention, since the alkali resistance itself of the rubber sealing body is improved, the leakage of the driving electrolyte can be prevented. Therefore, the reliability of the aluminum electrolytic capacitor having low loss and low impedance characteristics can be improved, so that the present invention has great industrial and practical value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing components of an aluminum electrolytic capacitor.

FIG. 2 is a vertical sectional view of the aluminum electrolytic capacitor.

[Explanation of symbols]

 2 Capacitor element 3 Anode lead terminal 4 Cathode lead terminal 5 Rubber sealing body 6 Aluminum case 31, 41 Aluminum round bar part 51, 52 Terminal insertion hole of rubber sealing body

Claims (2)

[Claims] 1. A capacitor element wound between an anode foil and a cathode foil via an electrolytic paper, and an aluminum lead terminal and a cathode lead terminal of the capacitor element drawn out from the anode foil and the cathode foil. A rubber sealing member in which each round bar portion is fitted in each terminal insertion hole;
A case in which the capacitor element impregnated with a non-aqueous driving electrolyte containing either a quaternary ammonium salt or an imidazolinium salt is sealed together with the rubber sealing body. A polar aluminum electrolytic capacitor characterized in that at least the inside of the terminal insertion hole on the cathode side is coated with an alkali-resistant coating. 2. The polar aluminum electrolytic capacitor according to claim 1, wherein the alkali-resistant coating is a silicon coating on the entire surface of the sealing rubber body.