JP4082407B2 - Aluminum electrolytic capacitor - Google Patents

Description

  The present invention relates to a highly reliable aluminum electrolytic capacitor having a low moisture content and having a low moisture content, having a low moisture content, having a low appearance change and a characteristic deterioration even when used at a high temperature for a long time. It is.

  As shown in FIG. 1, in the conventional aluminum electrolytic capacitor, an aluminum foil having a dielectric layer formed by an anodic oxidation treatment is used as an anode foil 2 after a surface enlargement treatment by an etching treatment, and the anode foil 2 and the cathode foil 3 are formed. A capacitor element 1 is formed by impregnating a drive electrolyte (hereinafter referred to as electrolyte) with a separator 4 such as manila hemp or kraft paper interposed between them, and forming a capacitor element 1. After the aluminum case 5 is inserted, the opening of the aluminum case 5 is sealed with a sealing material 6 made of rubber. The electrolytic solution draws out the electrostatic capacitance by closely contacting the roughened anode foil 2, and further, the leakage current can be kept low because the dielectric layer of the aluminum oxide film can be repaired by the chemical conversion ability of the electrolytic solution. It has a function. Among the characteristics of the electrolyte, electrical conductivity has a great influence on the impedance performance of the capacitor.

  In view of the above, in particular, low-voltage grade low impedance aluminum electrolytic capacitors with a rated temperature of 105 ° C. or higher and a rated voltage of 100 V or lower use γ-butyrolactone, which is excellent in low-temperature characteristics and chemical conversion, as a solvent. Electrolytic solutions having high electrical conductivity and being stable even at high temperatures using a quaternary ammonium salt as an electrolyte have been used.

For example, Patent Document 1 and Patent Document 2 are known as prior art document information related to the present invention.
Japanese Patent Laid-Open No. 62-145713 Japanese Patent Laid-Open No. 62-145715

  However, when an aluminum electrolytic capacitor using an electrolytic solution in which a quaternary ammonium salt of phthalic acid or maleic acid is dissolved in the above-mentioned γ-butyrolactone solvent is used continuously in a humid atmosphere, a strong alkali component is generated at the cathode portion. In particular, there is a possibility that the electrolyte solution leaks outside the capacitor due to erosion of the cathode lead and the sealing material 6 in contact with the cathode lead.

  In order to avoid such a problem, it is effective to use an electrolyte that generates little alkali even when energized, that is, an electrolyte that uses ethylene glycol and water as a solvent and an ammonium salt such as ammonium adipate as an electrolyte. .

  In addition, since an electrolyte using a γ-butyrolactone solvent has a flash point of around 100 ° C., an abnormal voltage or reverse voltage is applied to the aluminum electrolytic capacitor due to an abnormal operation of an electronic device, and a safety valve is activated. It could not be said that there was no risk of ignition when the liquid spouted.

  On the other hand, in a low-pressure class aluminum electrolytic capacitor having a guaranteed temperature of 85 ° C. and a rated voltage of 100 V or less, a mixed solvent with water added for the purpose of increasing the electrical conductivity of ethylene glycol is used as the solvent of the electrolytic solution. Although an electrolytic solution using an ammonium salt such as ammonium as an electrolyte can be used, in an aluminum electrolytic capacitor using this type of electrolytic solution, at a temperature equal to or higher than the boiling point of water (100 ° C.), which is one of the solvent components. It is difficult to maintain electrical performance for a long period of time. Within 1000 hours, the safety valve on the bottom part will be activated within a time, or in a no-load standing test at a temperature of 110 ° C. Problem such as over 5000 percent change rate + leakage current value after the test with respect to the period leakage current has occurred.

  In order to solve these problems, various phosphorus compounds can be added to the electrolyte solution for the purpose of suppressing the hydration reaction between the electrode foil and water, and various gas absorbents can be used to absorb the generated hydrogen gas. Although a method such as adding a nitro compound has been proposed, an electrolytic solution having a high water content such that the water content exceeds 20% even using these methods is used for a long time at a temperature of 100 ° C. or higher. It was difficult to maintain the electrical performance of the capacitor (in a high voltage capacitor whose rated voltage exceeds 100V, the oxide film as a dielectric is thick and strong, so the moisture content is 20 to 25%. If an electrolyte of the order is used, the electrical performance may be stable for about 1000 to 2000 hours at a temperature of 100 ° C. or higher, but a capacitor with a rated voltage of 100 V or less has a thin oxide film. In order, these problems have not been satisfactorily resolved.).

  Furthermore, in the case of using a highly conductive electrolyte having a water content of 20% or more at a temperature of 100 ° C. or higher for a long period of time, a low water content electrolyte having a water content of less than 20% is not a problem. The chlorine in the sealing rubber causes corrosion of the anode aluminum lead in a long-time high-temperature load test, resulting in an increase in leakage current or a corrosion breakage of the anode aluminum lead.

  An object of the present invention is to solve such a conventional problem and to provide a highly reliable aluminum electrolytic capacitor.

In order to solve the above-described problems, the present invention provides a capacitor element using an aluminum foil as an electrode, a driving electrolyte containing ammonium adipate having a water content of 20 to 90 wt% as a main electrolyte, and the driving electrolyte. And a sealing material for sealing the opening of the case, and the driving electrolyte is ammonium 1,7-octanedicarboxylate or (Chemical Formula 1) ) have free one and p- nitrobenzoic acid (Formula 2), the freezing point of the driving electrolyte is at -10 ° C. or less, chlorine contained amount of the sealing material for sealing material weight 100 ppm or less, 20 ° C., -10 ° C. to the impedance at 100kHz, the impedance ratio of 100kHz, the rated voltage 100V or less of aluminum is 4 or less It is obtained by the solution capacitor.

  As described above, according to the present invention, even when used at a high temperature for a long time, there is little change in appearance and characteristic deterioration, and an abnormal voltage or reverse voltage is applied to the aluminum electrolytic capacitor due to an abnormal operation of the electronic device. High reliability and impedance performance as well as its low temperature characteristics by using a high water content electrolyte that operates and has a low risk of ignition even when the electrolyte is ejected. An aluminum electrolytic capacitor having a voltage of 100 V or less can be configured.

The invention according to claim 1 of the present invention includes a capacitor element using an aluminum foil as an electrode, a driving electrolyte containing ammonium adipate having a water content of 20 to 90 wt%, and a driving electrolyte. A bottomed cylindrical case for storing the capacitor element impregnated with the liquid, and a sealing material for sealing the opening of the case, and the driving electrolyte is ammonium 1,7-octanedicarboxylate or 1), having free one and p- nitrobenzoic acid (Formula 2), the freezing point of the driving electrolyte is at -10 ° C. or less, chlorine contained amount of the sealing material, to plugging material weight Te is the 100 ppm or less, 20 ° C., -10 ° C. to the impedance at 100kHz, the impedance ratio of 100kHz, the following aluminum conductive rated voltage 100V is 4 or less Capacitors are highly reliable, and when an abnormal voltage or reverse voltage is applied to an aluminum electrolytic capacitor due to abnormal operation of an electronic device, etc., a safety valve is activated, and if an electrolyte is ejected, it will ignite. It has the effect of providing an aluminum electrolytic capacitor that is less dangerous and has excellent impedance characteristics and low temperature characteristics.

  In addition, when the water content of the electrolytic solution is less than 20%, the electrical conductivity at low temperature cannot be sufficiently exhibited, so that the impedance ratio of −10 ° C. and 100 kHz to the impedance at 20 ° C. and 100 kHz exceeds 4, which is not preferable. In the range where the moisture content exceeds 90%, the freezing point of the electrolyte may be higher than −10 ° C., so that the impedance performance at 20 ° C. can be ensured, but on the low temperature side of the capacitor. Is not preferable because the guaranteed temperature range becomes -10 ° C. or more and the guaranteed range is narrowed.

In addition, when a capacitor is formed using a sealing material having a chlorine content exceeding 100 ppm with respect to the weight of the sealing material, chlorides released from the sealing rubber are found when a rated voltage test is performed at a temperature of 100 ° C. or higher. It is not preferable because a large amount of water contained in the electrolytic solution dissociates into ions, and as a result, the anode aluminum lead is corroded at a high temperature.

The driving electrolyte is one selected from ammonium formate, ammonium acetate, ammonium lactate, ammonium glycolate, ammonium oxalate, ammonium oxalate, ammonium malonate, ammonium adipate, ammonium benzoate, ammonium glutarate, and ammonium azelate The above compound is contained as a main electrolyte .

The invention according to claim 2 is the aluminum electrolytic capacitor according to claim 1, wherein the driving electrolyte contains 0.01 wt% or more of a phosphorus compound.

  Next, the present invention will be described with specific examples.

  (Table 1), (Table 2), (Table 3), the electrolytic solution compositions of Embodiments 1 to 25 and Comparative Examples 1 to 8 of the present invention, the phosphorus compound or silicone compound adhesion amount of the separator used, and the electrode used The amount of phosphorus compound or silicone compound attached to the foil, the amount of chlorine contained in the sealing material used, the hardness of the sealing material and the surface-treated silicone compound, the thickness of the bottom surface of the aluminum case, and the compound treated on the inner surface of the aluminum case are shown.

  As a result of measuring the flash point of the electrolytic solutions of Embodiments 1 to 25 of the present invention by the Cleveland open method, it was confirmed that the test flame disappeared in the temperature range of 128 ° C to 134 ° C. Has no flash point. Moreover, as a result of leaving the electrolyte solution of Embodiment 1-25 of this invention for 24 hours in the low temperature thermostat set to the temperature of -30 degreeC, since the change of a property was not confirmed, the freezing point of electrolyte solution was It was also confirmed that it was −10 ° C. or lower.

  The chemical formulas of (Chemical Formula 1) to (Chemical Formula 8) described in (Table 1) and (Table 2) are shown below.

  (Table 4) to (Table 7) at −10 ° C./100 kHz with respect to the impedance at 20 ° C./100 kHz of the aluminum electrolytic capacitors configured using the electrolytic solutions of Embodiments 1 to 25 and Comparative Examples 1 to 8 Impedance ratio, rated voltage applied at a temperature of 110 ° C. for 1000 hours, and the amount of swelling at the bottom of the product after a no-load standing test, the rate of change in leakage current, the amount of solvent permeated through the sealing rubber, the corrosiveness of the anode aluminum lead, and The state of the sealing rubber is shown. There are two types of aluminum electrolytic capacitors used in this test: rated voltage 6.3 V-capacitance 560 μF (size: φ8 × 11 L) and rated voltage 50 V—capacitance 1500 μF (size: φ16 × 35.5 L). It is. For adhesion treatment of phosphorus compounds or silicone compounds in separators (manila hemp fiber material), electrode foils and sealing rubber (resin vulcanized isobutylene isopropylene rubber [butyl rubber] material), an aqueous solution of a phosphorus compound or silicone compound of any concentration After the separator, electrode foil, and sealing rubber were immersed therein, a drying treatment was performed at 100 ° C. for 1 hour. The amount of chlorine in the sealing rubber was measured with a total chlorine analyzer (product number: TSX-10) manufactured by Mitsubishi Chemical Corporation and converted into the amount of chlorine per weight of the sealing rubber.

  From the results of (Table 4) to (Table 7), the aluminum electrolytic capacitor of the present invention has a low impedance ratio, and even in a life test at 110 ° C., the swelling amount (L dimension change) and leakage current of the bottom surface of the aluminum case It can be seen that the rate of change of the value is small, the corrosiveness of the anode aluminum lead, and the sealing rubber does not pop out.

The partially cutaway perspective view which shows the structure of the aluminum electrolytic capacitor containing one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode foil 3 Cathode foil 4 Separator 5 Aluminum case 6 Sealing material

Claims (2)

A capacitor element using an aluminum foil as an electrode, a driving electrolyte containing ammonium adipate having a water content of 20 to 90 wt% as a main electrolyte, and a bottomed housing for housing the capacitor element impregnated with the driving electrolyte A cylindrical case and a sealing material that seals the opening of the case,
The driving electrolytic solution, 1,7-octane ammonium dicarboxylic acid or (Formula 1), either the p- nitrobenzoic acid has free and freezing point of the driving electrolyte of (of 2), -10 ° C. The chlorine content of the sealing material is 100 ppm or less with respect to the weight of the sealing material, and the impedance ratio of −10 ° C. and 100 kHz with respect to the impedance at 20 ° C. and 100 kHz is 4 or less. Aluminum electrolytic capacitor.

The aluminum electrolytic capacitor according to claim 1, wherein the driving electrolyte contains 0.01 wt% or more of a phosphorus compound.

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