JPS58207620A - 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.

Generally, an aluminum electrolytic capacitor using aluminum foil as an electrode is constructed as shown in FIG. In other words, the surface area is expanded by electrochemically roughening the aluminum foil, and a dielectric oxide film is formed on this interface by anodic oxidation to form an anode body, and this anode body is used as a cathode facing the separator. At the same time as winding with foil, driving electrolyte (hereinafter referred to as paste)
The capacitor element 1 is impregnated with the capacitor element 1, and the capacitor element 1 is housed in a bottomed cylindrical metal case 2, and a sealing rubber 4 through which the lead wire 3 passes is inserted into the opening of the metal case 2. Then, the open end of the metal case 2 is sealed by drawing and curling.

Unlike other capacitors, this type of aluminum electrolytic capacitor uses a paste composed of ethylene glycol, ethylene glycol monomethyl ether, N11N-dimethylformamide, boric acid, adipic acid, etc. 4, the paste gradually evaporates and evaporates, resulting in deterioration of characteristics such as a decrease in capacitance and an increase in loss.

For this reason, improvements have been made to extend the life of aluminum electrolytic capacitors by examining sealing materials and sealing methods.
came. In particular, what is shown in FIG. 2 is a remarkable example of improvements made to this sealing member and sealing method. That is,
This is an aluminum electrolytic capacitor in which a sealing member 5 made of a non-rubber-like elastic material such as polytetrafluoroethylene is press-fitted into the opening of a metal case 2 by a compression method to seal it. In addition,
6 is a guide fitting used when the sealing member 6 is completely press-fitted.

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 life time is significantly extended by 1. Furthermore, the mechanical stress of the external lead does not propagate to the internal capacitor element 1 because the hardness of the sealing member 5 is harder than ordinary rubber, so that leakage current characteristics are stable.

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

In other words, the sealing member 5 of this type of aluminum electrolytic capacitor is press-fitted into the opening of the metal case 2 using a press method using a resin material such as tetrafluoroethylene, and the sealing member 5 of this type of aluminum electrolytic capacitor As shown in Table 1, there are differences in the coefficient of expansion of aluminum electrolytic capacitors, so 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, thermal expansion and This causes a difference in shrinkage and causes the paste to leak from the gap at the contact interface between the side wall of the metal case 2 and the sealing member 5. Furthermore, the part of the lead wire 3 that is embedded in the sealing member 5 is also a contact part between the resin material and the metal, and even if there is In addition to this, since this portion is a portion where almost no dielectric oxide film is formed, this causes an increase in leakage current. If paste leakage occurs when this type of aluminum electrolytic capacitor is mounted on a printed wiring board together with other circuit components, short circuits may occur on the printed wiring board, and circuit characteristics may deteriorate due to increased leakage current. Take shelter.

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 pasting together a non-comb-shaped elastic body and a comb-shaped elastic body is inserted into the opening of a metal case and processed to seal it. . Hereinafter, the structure and operation of the present invention will be explained in detail.

In the present invention, in an electrolytic capacitor, a cylindrical metal case with a bottom is formed using a synthetic resin as a sealing member, and the paste leakage phenomenon caused by temperature cycle tests is solved by improving the material and structure of the sealing part. As shown in Figure 3, a rubber soft elastic body with strong passage resistance to organic solvents such as ethylene glycol, ethylene glycol monomethyl nityl, and N-N dimethylformamide used in pastes; A sealing member 9 made by laminating a non-rubber-like elastic body 8 such as a synthetic resin is used, and the sealing member 9 is inserted into the opening of the metal case 2, and the open end is sealed by drawing. It is something. This sealing member 9 includes a rubber-like elastic body 7
is inserted so that it is inside the metal case 2. Also,
Is the sealing member 9 approximately the same as the inner diameter of the metal case 2?
Or it has a slightly smaller outer diameter. This dimensionally different sealing member 9 is inserted into the opening of the metal case 2, and the part of the metal case 2 in contact with the rubber-like elastic body 7 is fully drawn, and the open end part of the metal case 2 is , processed to be smaller than other parts. That is, as shown in FIG. 3, if the diameter of the main body portion of the metal case 2 in which the capacitor element 1 is housed is Dl, the diameter of the open end portion is D2, and the diameter of the aperture portion is D3, D1>D2. The finished product is sealed so that the relationship 〉D3 occurs.

When such an electrolytic capacitor according to the present invention is subjected to a test such as a temperature cycle, the expansion of the rubber-like elastic body 7 as the temperature rises is large, and the shrinkage part due to the drawing process absorbs the shrinkage as the temperature falls. No paste leakage occurs. In the present invention, the rubber-like elastic body 7 is sufficiently contracted by drawing, and the open end is made thinner, so that the metal case 2 does not expand or contract as the temperature rises or falls. Even if this occurs, the sealing member 9 can follow it, so a highly reliable electrolytic capacitor that does not cause paste leakage can be obtained.

Furthermore, as a result of the drawing process, the metal case 2 becomes Dl>D2, so the non-rubber-like elastic body 8 is strongly tightened, and the hole through which the lead wire 3 provided in the non-rubber-like elastic body 8 passes is Sufficient tightening prevents paste leakage. Moreover, in the electrolytic capacitor according to the present invention, as mentioned above, Dl>D2 and the open end is thin, so even if the internal pressure of the electrolytic capacitor rises abnormally due to an unexpected accident, the internal capacitor element 1 It doesn't seem to jump out.

Here, as a conventional product, a completed product (A
), as a conventional product, a product (B) completed by press-fitting a sealing member made by bonding polytetrafluoroethylene and ethylene propylene terpolymer (EPT) together using a compression method, and as a product of the present invention, - (B) was drawn. The completed product (C
) was conducted to examine paste leakage defects.

The results are shown in Table 2. In addition, the thermal shock test is -4
The sample was left at 0°C for 30 minutes and at +86°C for 30 minutes, and 5 cycles were repeated.

(Hereinafter, blank spaces) 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 causing paste leakage, and its industrial value is great.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional aluminum electrolytic capacitor, Figure 2 is a sectional view showing an aluminum electrolytic capacitor sealed by a suppression method using a non-rubber-like elastic sealing member, and Figure 3 is a sectional view showing a conventional aluminum electrolytic capacitor.
The figure 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...
Rubber-like elastic body, 8...Non-rubber-like elastic body, 9...
...Sealing member. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2 Figure 3, 9

Claims (2)

[Claims] (1) 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 filled with a non-rubber-like elastic body and a rubber-like elastic A sealing member made by bonding the metal case with the rubber-like elastic body is inserted into the metal case so that the rubber-like elastic body is placed inside the metal case, and a portion of the open end of the metal case in contact with the rubber-like elastic body is drawn and sealed. The diameter of the main body part that is stopped and in which the capacitor element of the metal case is housed is Dl, and the diameter of the open end part '(r D2.
An electrolytic capacitor configured to satisfy the relationship Dl>D2>D3 when the diameter of the aperture part is D3. (2) The electrolytic capacitor 0 according to claim 1, wherein the outer diameter of the sealing part is smaller than the inner diameter of the metal case.