JPS61139019A - 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 Field of Industrial Application The present invention relates to an electrolytic capacitor with an improved sealing body, and its purpose is to significantly improve reliability.

Conventional technology Generally, electrolytic capacitors are made by forming a dielectric film on the surface of a metal foil with valve action such as aluminum or tantalum through anodizing treatment to form an anode foil, as shown in Figure 3.
This is wound with a separator such as electrolytic paper interposed between it and the opposing cathode foil, and is impregnated with a driving electrolytic solution (hereinafter referred to as electrolytic solution) to form a capacitor element 1. Internal lead 5 pulled out from
The external lead wire 4, which can be soldered and connected to the internal lead 5, is inserted into the insertion hole of the elastic sealing body 3, and is housed in the metal case 2, and the opening of the case 2 is wrapped and sealed. There is.

In the electrolytic capacitor configured as described above, since an electrolytic solution is used, when the temperature rises, the electrolytic solution passes through the elastic sealing member 3 and escapes to the outside, so it cannot be used in a high-temperature atmosphere for a long period of time. At this time, the electrolyte evaporates to dryness, resulting in the capacitor not functioning as a capacitor or increasing the loss value of the capacitor. For this reason, isobutylene/isoprene rubber has been frequently used as a sealing material with low gas permeability.

Problems to be Solved by the Invention The above-mentioned isobutylene/isoprene rubber has lower gas permeability than any other rubber, and is not suitable for electrolytes using highly volatile organic solvents such as dimethylformamide (hereinafter referred to as DMF). Therefore, it is essential to maintain airtightness at high temperatures.

However, when used for a long period of time at a high temperature of about 150° C., the hardness decreases. Furthermore, when immersed in a highly polar solvent such as DMF at high temperature, it tends to swell, soften, and partially dissolve.

Means for Solving the Problems The present invention solves the above-mentioned problems.The opening of the case housing the capacitor element is made of hexafluorinated ethylene propylene resin on the surface facing the capacitor element and isobutylene/isoprene rubber on the outer surface. This electrolytic capacitor is characterized in that it is sealed by fitting a sealing body which is integrally constructed with the following.

Hexafluoroethylene propylene resin is placed on the opening of the working case and on the surface facing the capacitor element to prevent isobutylene/isoprene rubber from being attacked by the solvent in the electrolyte and to prevent the hardness of the rubber from decreasing at high temperatures. Reinforce.

Example Examples of the present invention will be described below.

Table 1 shows the hydrogen gas permeability of hexafluorinated ethylene propylene resin and isobutylene/isoprene rubber, and Table 2 shows the hydrogen gas permeability of the same size fluorinated ethylene propylene resin and isobutylene/isoprene rubber after being left at 125°C for 1000 hours. , shows a comparison with the initial value of hardness measured after returning to room temperature.

Tables 2 and 3 show the changes in the rubber when immersed in DMF at 125°C for 50 hours.

Table 3 From these test results, the hexafluorinated ethylene propylene resin is excellent in electrolytes using DMF as a solvent, but has high gas permeability and lacks airtightness as an elastic sealant. Isobutylene/isoprene rubber has good airtightness, but DMF
It is not suitable for areas that come into contact with electrolyte solutions containing a solvent as a solvent, and furthermore, the hardness decreases significantly when left at high temperatures.

Focusing on the above points, when using a highly volatile electrolyte containing DMF, it is necessary to , hexafluoroethylene propylene resin 6b is present, and in order to maintain airtightness, isobutylene/isoprene rubber 6a is present on the outside of the elastic sealing body 6, which is integrally molded to prevent the electrolyte from permeating. At the same time, we were able to maintain airtightness and obtain a highly reliable electrolytic capacitor. Even when relatively stable solvents containing ethylene glycol are used, isobutylene and
It goes without saying that an electrolytic capacitor with higher reliability can be obtained by using the two-layer sealing body 6 made of isoprene rubber 6a and hexafluoroethylene propylene resin 6b.

Next, the rating is 10V, 220μF, and the case size is 10mmφ.
Conventional isobutylene/isoprene rubber and hexafluorinated ethylene propylene resin of the present invention are used as elastic sealing bodies for electrolytic capacitors with lead wires in the same direction, rated at 50 V, 10 μF, and case size 8 mm φ x 161 mm. A life test was conducted on a product using a two-layer rubber consisting of isobutylene and isoprene rubber in an atmosphere of 125° C. by applying a rated voltage for 2000 hours. The results are shown in Table 4, Figures 4 and 5.

The electrolyte used in this test was a solvent mixed with DMF. The test was conducted for 20 pieces each.

As is clear from the test results, the electrolytic capacitor using the two-layer sealing body of the present invention is a high-performance, long-life, highly reliable capacitor that can guarantee high temperatures.

The same effect can be obtained from this two-layer rubber as a multi-layer structure made by laminating silicone rubber or similar materials, or as a rubber agent for bonding with a resin base such as phenol.

Effects of the Invention Since the electrolytic capacitor of the present invention is constructed as described above, the sealing body is not dissolved or swollen by the solvent in the electrolyte, and the hardness of the sealing rubber is small at high temperatures. An electrolytic capacitor using this sealing body has a long life and high reliability, which can guarantee high temperatures, and has extremely high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the electrolytic capacitor of the present invention.
FIG. 2 is a perspective view of an embodiment of an elastic sealing body for a capacitor according to the present invention, and FIG. 3 is a sectional view of a conventional electrolytic capacitor.
Figure 4 shows an electrolytic capacitor with a rating of 10V and 220μF.
(a) is a capacitance one-hour characteristic diagram, (rl) is a tan δ one-hour characteristic diagram, Figure 5 is an electrolytic capacitor with a rating of 50■, 10μF, (a) is a capacitance one-hour characteristic diagram, and (rl) is a one-hour characteristic diagram of capacitance. )
is a tan δ one-hour characteristic diagram. 1: Capacitor element 2: Case 3.6: Elastic sealing body

Claims (1)

[Claims] The opening of the case housing the capacitor element is sealed by fitting a sealing body made of hexafluoroethylene propylene resin on the surface facing the capacitor element and isobutylene/isoprene rubber on the outer surface. Features of electrolytic capacitors.