JPS6130727B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is an electrolytic capacitor that improves the longevity characteristics of a capacitor by preventing corrosion of a capacitor element caused by penetration of the halogenated hydrocarbon into the capacitor when the electrolytic capacitor is cleaned with a halogenated hydrocarbon. Regarding electrolytes for use. Conventional electrolytic capacitors consist of a capacitor element formed by winding an electrode foil and a spacer, and the capacitor element is housed in a case and sealed with a rubber stopper.The driving electrolyte that impregnates the capacitor element is ethylene glycol-boric acid. Ammonium-based and ethylene glycol-ammonium adipate-based materials were used. However, halogenated hydrocarbons, such as 1.1.1 trichloroethane, which are used as cleaning agents in the process of cleaning electrolytic capacitors and the process of removing solder flux used when attaching them to printed circuit boards, have a negative impact on the halogenated hydrocarbons. When immersed or in a steam bath, it penetrates through the rubber plug and enters the inside of the capacitor, where it decomposes and generates chlorine ions.
The chlorine ions corrode the electrode foils and lead terminals of the capacitor element, and this corrosion is particularly severe when voltage is applied to the electrolytic capacitor, sometimes resulting in disconnection of the lead terminals. The present invention has been made in view of the above points, and it is an object of the present invention to provide an electrolytic solution for an electrolytic capacitor that can prevent corrosion even if a halogenated hydrocarbon used for cleaning infiltrates the inside of the case. This is intended to improve the life of the electrolytic capacitor. This will be explained below using examples. The electrolytic solution according to the present invention is composed of ethylene glycol (EG), water, and ethanolamine adipate, which is a salt of ethanolamine and adipic acid, and the composition of an example thereof is shown in the table. In addition, Conventional Example 2 is an electrolytic solution containing some water and is described in Japanese Patent Application Laid-Open No. 54-91754.

【table】

[Table] The mono-, di-, and triethanolamine adipates listed in the table are a type of ethanolamine adipate, and can be produced by mixing adipic acid and ethanolamine and heating or mixing in ethylene glycol. But these are
If it exceeds 40wt%, it will no longer dissolve in ethylene glycol. A capacitor element made by winding an electrode foil and a spacer was impregnated with an electrolytic solution having the composition shown in this table, and the capacitor element was housed in an aluminum case and sealed with a rubber stopper. Make an electrolytic capacitor with lead wire terminals in the same direction, and connect the electrolytic capacitor to 1.1.
Figures 1 to 4 show the characteristics of 50 samples each immersed in the vapor of 1-trichloroethane for 10 minutes and left at 105°C with a voltage of 50V applied. That is, FIG. 1 is a curve diagram showing the relationship between the standing time and the number of explosion-proof valve operations, and for 1000 hours, the number of corrosion confirmed after complete disassembly is shown. FIG. 2 is a curve diagram showing the relationship between the standing time and the capacitance change rate, FIG. 3 is a curve diagram showing the relationship between the standing time and tan δ, and FIG. 4 is a curve diagram showing the relationship between the standing time and leakage current. Moreover, FIG. 5 shows the specific resistance of an electrolytic solution composed of 20 wt % monoethanolamine adipate and the balance ethylene glycol when the amount of water added is varied. According to this, when the water content is less than 5 wt%, the change and absolute value are large, and this is a tendency that coincides with Reference Example 2 (curve G) in FIG. 3, which will be described later. Therefore, by making the electrolytic solution contain 5 wt% or more of water, there is an effect that the specific resistance can be reduced, and tan δ can be improved. Note that the symbols attached to the curves in FIGS. 1 to 4 are the symbols shown in the table, and represent the types of electrolyte solutions. According to this result, in the conventional example 1 and conventional example 2 (curves A and B), all valves operate at the number of valve operations shown in Fig. 1, and in the reference example (curve H), all valves operate.
Seven corrosions occurred in 1000 hours. Curves A and B show that as a result of the disassembly investigation, the corrosion phenomenon was remarkable, and the internal pressure rose due to the corrosion, causing the explosion-proof valve to operate. In addition, the capacitance change rate and tan δ of Reference Example 1 (curve F) in Figures 2 and 3 change because the electrode foil causes a boehmite reaction due to too much water contained in the electrode solution. In reference example 2 (curve G) in FIG. 3, the electrolytic solution does not contain any water, so the specific resistance is large from the beginning. Therefore, the electrolytic solution of the above example can be said to consist of 27 to 5 wt% water, 40 to 5 wt% ethanolamine adipate, and the balance ethylene glycol. As described above, in the electrolytic capacitor using the electrolytic solution for electrolytic capacitors according to the present invention, corrosion does not occur inside the capacitor even when halogenated hydrocarbon is used as a cleaning solution, and the capacitance, tanδ, and leakage current are reduced. You can get something stable. Of course, it goes without saying that similar characteristics can be obtained even when no halogenated hydrocarbon is used as the cleaning agent.

[Brief explanation of the drawing]

Figures 1 to 4 all show the relationship between the standing time and each characteristic when electrolytic capacitors impregnated with an electrolyte according to the present invention, a conventional example, and a reference example are left under voltage application at 105°C. In the curve diagrams, Figure 1 shows the number of explosion-proof valve operations, Figure 2 shows the capacitance change rate, Figure 3 shows tanδ, Figure 4 shows the leakage current, and Figure 5 shows the amount of water added. It is a curve diagram showing the relationship between and specific resistance.

Claims (1)

[Claims] 1. An electrolytic solution for electrolytic capacitors consisting of 27-5 wt% water, 40-5 wt% salt of ethanolamine and adipic acid, and the balance ethylene glycol.