JPH076935A - Manufacture of electrolytic capacitor - Google Patents

Abstract

PURPOSE:To contrive the improvement of the reliability of a product, a reduction in the aging electric energy of an electrolytic capacitor and moreover, the improvement of the productivity of the capacitor by improving the mechanical joints of the connection parts of aluminium rivets provided on a sealing terminal plate and on the lead tabs from the capacitor element of the electrolytic capacitor. CONSTITUTION:The connection parts of aluminium rivets provided on a sealing terminal plate and on lead tabs from a capacitor element of an electrolytic capacitor are made to mechanically bond to the tabs and thereafter coated with chemically stable silicone rubber at the connection parts by application, spraying or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the lead tab and the sealing terminal plate portion of an electrolytic capacitor, and more particularly to a method of manufacturing an electrolytic capacitor in which the lead tab of the capacitor element and the washer tightening portion have improved electrochemical stability. .

[0002]

2. Description of the Related Art Conventionally, in a sealed portion of an electrolytic capacitor, a sealing terminal plate is mechanically clamped and fixed by curling of an outer metal case, and a lead tab drawn from a capacitor element is connected to an aluminum rivet provided on the sealing terminal plate. Was. The electrochemical stability of the part was retained by this connection. However, with this connection alone, the driving electrolyte affected the lead tabs, rivets, and washers, and the electrochemical stability was insufficient.

Therefore, various attempts have been studied such as caulking and welding at this connecting portion to connect the lead tab for pulling out the capacitor element to the aluminum rivet provided on the sealing terminal plate and strengthening the connection strength.

However, even in the techniques studied by the various combinations described above, the electrolytic solution conversion coating of the rivet and washer has a great influence not only on the aging but also on the reliability of the product. Specifically, when it is commercialized as a capacitor, there is a serious problem in safety such as a case where the insulation breakdown is apt to occur at the relevant part due to an electric shock such as the application of an overvoltage and the explosion-proof valve does not operate to reach a short. . In addition, as in Japanese Utility Model Application Laid-Open No. 56-40646, there is a rivet portion coated with an insulating resin, but it has a drawback that it causes corrosion or cracks in the resin.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the lead tab from the capacitor element and the rivet provided on the sealing terminal plate are brought into contact with each other by sufficient mechanical coupling.
Further, it ensures the electrochemical stability of the connection part.

[0006]

The present invention has been found as a result of various studies for solving the above problems. The essence of the present invention is to mechanically connect the lead-out lead tab from the capacitor element and the rivet provided on the sealing terminal plate to improve the electrochemical stability of the connection. After the above step, a chemically stable silicone rubber is applied and treated by spraying to ensure the electrochemical stability of the connection portion. That is, in an electrolytic capacitor having a structure in which an anode foil and a cathode foil are wound through a separator, impregnated with an electrolytic solution, housed in a case, and sealed with a sealing terminal plate, a lead tab from a capacitor element and a sealing terminal plate are A method for producing an electrolytic capacitor, characterized in that electrochemical stability is ensured by mechanically coupling the connecting portion of the provided rivet and then silicon coating with silicon rubber.

[0007]

In the past, the driving electrolyte, the rivet, and the washer connection portion were in direct contact with each other, and a chemical reaction or the like is likely to occur. When commercialized as a capacitor, this is very problematic in terms of safety such as a case where a dielectric breakdown is apt to occur at the relevant portion due to an electric shock such as application of an overvoltage and a short circuit is reached without operating the explosion-proof valve. However, according to the present invention, the connecting portion does not come into direct contact with the driving electrolytic solution, and in addition, the silicone rubber is stable without reacting with the driving electrolytic solution. Further, the operation for the process of the present invention can be introduced very easily. Furthermore, the leakage current can be greatly improved. Therefore, the present invention greatly contributes to the improvement of product reliability.

[0008]

EXAMPLES Specific examples of the present invention will be described below. Rating 400V 82μF, 400V 150μF and 4
For three types of CE69 type electrolytic capacitors of 00V390μF, select an organic acid electrolyte used as a driving electrolyte, select lead tabs, rivets, and washers with washers, and then coat with silicon rubber for curling. The behavior of aging was investigated. (Example 1) Using a commercially available silicone rubber (Shin-Etsu Silicon KE-347T), the lead tab, the rivet, and the washer were washer-tightened, and then the silicone rubber was applied so as to cover all of them, and at room temperature. It was air-dried for 3 minutes and used for the above product. (Comparative Example 1) The lead tab, rivet, and washer in Example 1 were subjected to washer tightening, and then silicone rubber was not applied to the lead tab, the rivet, and the washer, and they were used as they were without treatment. Example 1
From each of the two products of Comparative Example 1 were produced,
Curling was performed and aging was performed. The aging voltage was set to 425 V, and the aging temperature was set to 65 ° C. A voltage was applied under these conditions, and the voltage arrival time up to 425 V and the aging current decrease for 30 minutes after that were observed.
The results are summarized below. (1) From Table 1, as the rated capacitance increases, the voltage arrival time up to 425V becomes shorter, and the difference between treated and untreated products made of silicone rubber for the rivet and washer becomes smaller. Further, it is understood from FIGS. 1 to 3 that the difference in the voltage rise curve appears from around 200 V, and the fluctuation of the voltage around this is largely due to the formation of the electrolytic solution of the rivet and washer. The degree of influence is greater as the electrostatic capacity is smaller, and is greater as the proportion of rivets and washers is larger.

[0009]

[Table 1] (2) Table 2 shows a comparison of the amount of aging electricity that reaches the set voltage of 425V. It can be seen that the amount of electricity consumed by the lead tab, rivet and washer is 2-3 coulombs. This electric quantity is 20.6% of the total aging electric quantity at 400V82μF, 400V150μF
Corresponds to 18.2% and 400 V to 390 μF corresponds to 9.3%.

[0010]

[Table 2] (3) When the washer-clamped part after aging was observed with a microscope, the rivet crushed by the washer-clamping had a considerable amount of oxide film product of the driving electrolyte solution. This revealed that a considerable amount of electricity was consumed. (4) Tables 3 and 4 show the results of an investigation of the effects on the product characteristics when the rivets and washers are treated with silicone rubber, but the characteristics are hardly affected even when the treatment with silicone rubber is carried out.

[0011]

[Table 3]

[0012]

[Table 4]

[0013]

As shown in Tables 1 to 4, according to the present invention, an aluminum rivet connected to an aluminum rivet extending from the terminals is provided inside a terminal plate having lead tabs drawn from the anode foil and the cathode foil and external electrode terminals. In the capacitor in which the lead tab was washer-tightened via the washer, was coated with silicon rubber, and was mechanically fastened by curling or the like, the connection portion had extremely good electrochemical stability. According to the method of the present invention, power consumption due to aging can be significantly reduced and energy saving can be realized. In addition, process troubles were greatly reduced, and process yield and productivity were improved. Further, in the reliability test, the leakage current characteristic can be greatly improved as compared with the conventional product, and the industrial and practical value of the present invention is great.

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[Procedure amendment]

[Submission date] March 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing an aging voltage rise curve of an electrolytic capacitor rated at 400 V and 82 μF.

FIG. 2 is a diagram showing an aging voltage rise curve of an electrolytic capacitor rated at 400 V and 150 μF.

FIG. 3 is a diagram showing an aging voltage rise curve of an electrolytic capacitor rated at 400 V and 390 μF.

[Explanation of symbols] 〇 No rivet part processed ● Rivet part coated with silicone rubber

Claims (1)

[Claims] 1. A capacitor element formed by winding an anode foil and a cathode foil with a separator paper in between is housed in a case, and a lead tab pulled out from the anode foil and the cathode foil is placed inside a sealing terminal plate having external electrode terminals. A method for manufacturing an electrolytic capacitor, comprising: crimping a lead tab to an aluminum rivet connected from the terminal via an aluminum washer, and then coating the crimped joint portion with silicon rubber.