JPH031818B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is for use in electrolytic capacitors that improve the life characteristics of capacitors by preventing corrosion of capacitor elements caused by penetration of halogenated hydrocarbons into the capacitors when electrolytic capacitors are cleaned with halogenated hydrocarbons. Regarding electrolyte. 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.
Ethylene glycol (hereinafter referred to as EG)-ammonium borate, EG-ammonium adipate, and the like have been used as driving electrolytes to impregnate capacitor elements. 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, cannot be used by dipping them in the halogenated hydrocarbons or When exposed to steam baths, it penetrated the rubber plug and entered the capacitor, where it decomposed and produced chlorine ions. The chlorine ions thus generated corrode the electrode foils and lead terminals of the capacitor element, but this corrosion is particularly severe when voltage is applied to the electrolytic capacitor, and sometimes leads to disconnection of the lead terminals. The present invention has been made in view of the above points, and provides an electrolytic solution for electrolytic capacitors that can prevent corrosion even if halogenated hydrocarbons used for cleaning penetrate into the case. The aim is to improve the lifespan of electrolytic capacitors. This will be explained below using examples. The electrolyte of the present invention is water - ammonium adipate - ethanolamine adipate - the balance is EG.
The compositions of the examples are shown in the table. ,
Conventional Example 1 is EG-ammonium adipate, Conventional Example 2 is an electrolytic solution containing some water,
This is described in Publication No. 91754.

[Table] Mono-, di-, and triethanolamine adipate listed in the table is a type of ethanolamine adipate, and can be produced by mixing adipic acid and ethanolamine and heating or mixing in EG. However, these become insoluble in ethylene glycol when the amount exceeds 40 wt%. Similarly, ammonium adipate does not dissolve if it exceeds 20 wt%. A capacitor element made by winding 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 plug. 1.1.1 Electrolytic capacitors with lead wire terminals in the same direction were made. 1.1.1 The electrolytic capacitors were immersed in trichloroethane vapor for 10 minutes. 50 pieces of each were used as samples to evaluate the characteristics when a voltage of 50 V was applied and left at 105°C. It is shown in FIGS. 1 to 4.
That is, FIG. 1 is a curve diagram showing the relationship between the standing time and the number of explosion-proof valve operations, and at 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. The symbols attached to the curves in Figures 1 to 4 are A to J shown in the table.
This symbol uses the symbol to represent the type of electrolyte. According to the results, all valves operated in conventional example 1 (symbol A) and conventional example 2 (symbol B) at the number of valve operations shown in Fig. 1, and in reference example 3 (symbol I), all valves operated for 1000 hours.
There were 7 areas of corrosion. As a result of the disassembly investigation, the curves A and B indicate that the corrosion phenomenon was remarkable, and the internal pressure rose due to the corrosion, causing the explosion-proof valve to operate. Reference example 1 (symbol G) has the capacitance change rate and tanδ shown in FIGS. 2 and 3.
However, the electrolytic foil undergoes a boehmite reaction due to the water contained in the electrolytic solution, resulting in a large change.In reference example 2 (symbol H), the electrolytic solution does not contain any water, so the specific resistance changes from the beginning. It's big. Further, since Reference Example 4 (J) does not contain ammonium adipate, it has a large non-resistance from the initial stage. Therefore, the electrolyte of the present invention contains 27 to 5 wt of water.
%, ammonium adipate 20-1 wt%, ethanolamine adipate 40-5 wt%, and the balance consists of EG. As described below, 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, leakage current You can get a stable result. 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]

The drawings are all curve diagrams showing 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 with a voltage applied at 105°C. The figure shows the number of explosion-proof valve operations, Fig. 2 shows the capacitance change rate, Fig. 3 shows tan δ, and Fig. 4 shows the leakage current.

Claims (1)

[Claims] 1 Water 27~5wt%, ammonium adipate 20~
1wt%, ethanolamine adipate 40~5wt%,
Electrolyte for electrolytic capacitors, the remainder of which is ethylene glycol.