JPS58207619A - Electrolytic condenser - 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 The present invention relates to an electrolytic capacitor, and more particularly to an improvement in the sealing portion of an electrolytic capacitor.

An aluminum electrolytic capacitor that normally uses aluminum foil as an electrode is constructed as shown in Figure 1. That is, the surface area is expanded by electrochemically roughening the aluminum foil, and then a dielectric thinning layer is formed on this surface by anodization to form a single anode, and this anode body is inserted through a separator. The capacitor element 1 is formed by winding it together with the opposing cathode foil and impregnating it with a driving electrolyte (hereinafter referred to as paste), and then placing the capacitor element 1 inside a bottomed cylindrical metal case 2. It is constructed by inserting a sealing rubber 4 through which the lead wire 3 passes through the opening of the metal case 2 and sealing the open end of the metal case 2 by drawing and curling.

This type of aluminum electrolytic capacitor differs from Ike capacitors in that it uses ethylene glycol/L/, ethylene glycol
Monomethyl ether, N-N-dimethylformamide,
Since a paste composed of silica, adipic acid, etc. is used, the paste gradually evaporates and evaporates through the sealing rubber 4, resulting in deterioration of characteristics such as a decrease in capacitance and an increase in loss. .

For this reason, efforts have been made to extend the life of aluminum electrolytic capacitors by examining sealing members and sealing methods. In particular, what is shown in FIG. 2 is a remarkable example of improvements in this sealing member and sealing method.

That is, using a sealing member 5 made of a non-rubber-like elastic material such as polytetrafluoroethylene, the metal case 2 is closed by a compression method.
This is an aluminum electrolytic capacitor that is press-fitted into the opening and sealed. In addition, 6 is a guide metal fitting used when press-fitting the sealing member 5.

The feature of this aluminum electrolytic capacitor is that unlike the rubber material, the diffusion coefficient of the paste of the sealing member 5 is almost 0.
The evaporation and loss of the paste is extremely small, and the service life is greatly extended. Furthermore, since the sealing member 5 has a harder hardness than ordinary rubber and the mechanical stress of the external lead does not propagate to the internal capacitor element 1, the leakage current is stable.

However, this type of aluminum electrolytic capacitor has the following problems.

In other words, this kind of aluminum: Sealing member 5 of electrolytic capacitor
is a resin material such as tetrafluoroethylene, which is press-fitted into the +, 1li1, and b parts of the extra case 2 using the pressing method, and the expansion coefficients of the metal case 2 and this type of resin are shown in Table 1. Because of the difference shown in Figure 3, in tests that involve rapid temperature changes such as temperature cycle tests and thermal shock tests, which are one of the important characteristics of aluminum electrolytic capacitors, differences occur in expansion and contraction due to heat. As shown in the figure, a phenomenon occurs in which the paste leaks from the gap at the contact interface between the side wall of the metal case 2 and the sealing member 5.

Furthermore, the drawer lead wire 3. The portion embedded in the sealing member 6 is also a contact portion between the resin material and the metal, and the paste also leaks to the outside due to the difference in coefficient of thermal expansion at this portion. In addition, since this portion is a portion where almost no dielectric tube coating is formed, it becomes a cause of an increase in leakage current. If paste leakage occurs when this type of aluminum electrolytic capacitor is attached to a printed circuit board along with other circuit components, short circuits may occur on the printed wiring board, and circuit characteristics may deteriorate due to increased leakage current. Resulting in. , 11' The present invention has been made in view of the current situation, and aims to eliminate the conventional drawbacks by improving the sealing part.

That is, the present invention is characterized in that a sealing member made by bonding a non-rubber-like elastic body and a rubber elastic body is inserted into the opening of a metal case, and is sealed by performing a drawing process. be.

Hereinafter, the structure and operation of the present invention will be explained in detail.

In the present invention, in an electrolytic capacitor in which a bottomed cylindrical metal case is sealed with a sealing member made of synthetic resin and rubber, the paste leakage phenomenon that occurs during temperature cycle tests, etc. can be prevented by changing the material and structure of the sealing member. As shown in Figure 4, this problem can be solved by improving the organic solvents used in pastes, such as ethylene glycol, ethylene glycol monomethyl ether, and N-N dimethylformamide, which have strong resistance to passage. Non-rubber-like elastic body 7 made of synthetic resin such as polytetrafluoroethylene
The metal case 2 is sealed using a sealing member 9 formed by adhering rubber elastic biasing bodies 8 to the upper and lower surfaces of the metal case 2.

When sealing is performed using the sealing member 9 having a three-layer structure as in the present invention, the non-rubber-like elastic body 7 located in the middle has extremely low permeability to the organic solvent as described above, and therefore has a long life. In addition, drawing and curling are performed on the upper and lower surfaces in contact with the laminated rubber-like elastic body 8, which improves sealing properties and also improves sealing performance in temperature cycle tests and thermal shock tests. Since the rubber-like elastic body 8 expands and contracts with temperature changes, it is possible to obtain a highly reliable electrolytic capacitor that is highly effective in preventing paste leakage.

Here, as a conventional product, a completed product (A
), a product of the present invention sealed with a three-layered sealing member made by laminating polytetrafluoroethylene and ethylene propylene terpolymer (EPT) (B)
A thermal shock test was conducted to investigate paste leakage defects. The results are shown in Table 2. In addition, the thermal shock test is -40
5 cycles were repeated by leaving the tubes at +86° C. for 30 minutes and at +86° C. for 30 minutes.

As is clear from the results in Table 2, the products of the present invention can sufficiently withstand the thermal shock test.

As described above, the electrolytic capacitor according to the present invention has high reliability without paste leakage even when tested with temperature changes, and its industrial value is significant.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional aluminum electrolytic capacitor.
Figure 2 is a cross-sectional view showing an aluminum electrolytic capacitor sealed by a suppression method using a sealing member made of a non-rubber-like elastic material; FIG. 4 is a sectional view showing an electrolytic capacitor according to an embodiment of the present invention. 1...Capacitor element, 2...Metal case, 3...Output lead wire, 7...
Non-rubber-like elastic body, 8...Rubber-like elastic body, 9...
...Sealing member. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 85 Figure 2

Claims (1)

[Claims] The electrode foil is wound together with a separator and impregnated with electrolyte to form a capacitor element, and the capacitor element is housed in a metal case, and the opening of the metal case is covered with a rubber-like elastic material on the upper and lower surfaces of the non-rubber-like elastic body. An electrolytic capacitor sealed with a sealing member made by adhering an elastic body.