JPH06132171A - Manufacture of tab terminal for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To smooth a round rod part and then to improve the engagement with the through hole inner wall surface of a rubber hole sealing body by chemically polishing the round rod part of a tab terminal. CONSTITUTION:At least a round rod part 2 of a tab terminal 1 for electrolytic capacitor consisting of the round rod part 2 of aluminum, a flat part 3 of aluminum, and a leading wire 4 welded to the round rod part 2 is dipped into a chemical polishing bath for chemical polishing, thus preventing the internal electrolyte for drive from being leaked and obtaining a reliable electrolytic capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a tab terminal for an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art In an aluminum electrolytic capacitor, a capacitor element formed by winding an aluminum anode foil and an aluminum cathode foil through a separator paper is impregnated with a driving electrolytic solution, and the capacitor element is made of aluminum together with a rubber sealing body. It has a structure in which it is built in the outer case and sealed by sealing the outer case.

Tab terminals as lead-out terminals are fixed to each of the anode foil and the cathode foil by caulking or the cold weld method and are drawn out through the through holes of the rubber sealing body.

As shown in FIG. 1, the tab terminal 1 comprises a round bar 2 made of aluminum, a flat part 3 obtained by flattening the round bar 2, and a lead wire 4 welded to the round bar 2. Become. The lead wire 4 is made of a CP wire (copper coated steel wire) and is plated with solder or tin.

The flat portion 3 of the tab terminal 1 is fixed to the anode foil or the cathode foil, and the round bar portion 2 is fitted into the through hole of the rubber sealing body.

In recent years, in order to improve the characteristics of the capacitor, a driving electrolytic solution used for an electrolytic capacitor has been made highly conductive or stable at high temperatures.

For example, a solution obtained by dissolving a quaternary ammonium salt of O-phthalic acid or a quaternary ammonium salt of maleic acid as a solute in a solvent such as γ-butyrolactone or ethylene glycol is used as a driving electrolyte. ing.

[Problems to be Solved by the Invention]

Such a driving electrolytic solution has a low viscosity and is active, and liquid leakage is likely to occur from a minute gap between the rubber sealing body and the round bar portion of the tab terminal.

The aluminum wire used for the tab terminal is drawn from the aluminum raw material using a die. Therefore, the accuracy of the surface of the aluminum wire depends on the accuracy of the die used.

In the conventional tab terminal, the surface of the round bar portion of the tab terminal is rough and not smooth. When observing the surface with an electron microscope, the height is 0.2 to 1.0 μm.
It was confirmed that there were innumerable irregularities. Therefore, a minute gap is generated between the through hole of the rubber sealing body and the round bar portion, and the electrolyte leaks easily.

[Means for Solving the Problems]

However, in the present invention, in order to improve the fitting performance between the inner surface of the through hole of the rubber sealing body and the round bar portion of the tab terminal,
The round bar portion of the tab terminal is smoothed by chemical polishing.

In the present invention, not only the round bar portion of the tab terminal is chemically polished, but also the flat portion can be chemically polished at the same time to remove burrs on the flat portion.

In the chemical polishing, it is preferable to immerse the flat portion and the round bar portion of the tab terminal in the chemical polishing bath.

As the chemical polishing liquid, (1) NaOH, N
_{aNO 2, NaNO 3, Na 3} PO 4, H 2 O consisting of a solution (Alupol _{method), (2) H 3 PO} 4, H 2 SO
₄ , a solution consisting of HNO ₃ and H ₂ BO ₃ (Alupol
Method), and (3) a solution of H ₃ PO ₄ , HNO ₃ , and H ₂ O (Alcoa method) and the like.

Further, the chemical polishing conditions such as the liquid temperature and the processing time can be appropriately selected.

【Example】

The tab terminal shown in FIG. 1, the diameter of the round bar is 2.0
mm, the same length 6 mm, the flat portion width 2.5 mm, the same thickness 0.35 mm, and the same length 15 mm were prepared. The surface of the round bar had many irregularities with a height of 0.2 to 1.0 μm.

On the other hand, phosphoric acid 80.5% by weight, nitric acid 3.5
A weight% aqueous solution is maintained at a liquid temperature of 90 ± 2 ° C. to form a polishing bath, and the flat portion and round bar portion of the tab terminal are 180
It was immersed for 2 seconds and the tab terminals were chemically polished.

After chemical polishing, it was washed with water. Furthermore, boric acid 3
It was washed with an aqueous solution of wt% at a liquid temperature of 85 ± 1 ° C. Then, it was washed with pure water and dried. When the surface of this tab terminal was observed, the height of the surface irregularities was 0.01 to 0.0.
It became 3 μm and was smoothed. <Example 1>

Further, a tab terminal having an aluminum oxide film with a thickness of 300 nm formed on the flat portion and round bar portion by anodizing treatment is fixed to the anode foil and the cathode foil, and the anode foil, the cathode foil and the separator paper are interposed. As a capacitor element.

Γ-butyrolactone 75 was used for the capacitor element.
A driving electrolyte solution containing 50% by weight of tetraethylammonium maleate and 25% by weight was impregnated.

A capacitor element was assembled in an aluminum outer case together with a butyl rubber sealing body, and the diameter was 12.5 m.
m, length 25 mm, rated voltage 25 V, electrostatic capacity 1000
Prototypes of 20000 μF electrolytic capacitors were manufactured.

These electrolytic capacitors were placed at a temperature of 60 ° C. for 10
^The sample was exposed to a vacuum of ^-2 Torr for 200 hours.

When the electrolyte leakage state between the tab terminal and the through hole of the rubber sealing body was visually inspected, none was found. <Example 2>

The tab terminals fixed to the anode foil have a thickness of 30.
20000 electrolytic capacitors were manufactured in the same manner as in Example 1 except that a 0 nm oxide film was used and the tab terminals fixed to the cathode foil were not formed with an oxide film.

When the same test as in Example 1 was conducted, there was no leakage of the electrolytic solution. <Comparative example>

An electrolytic capacitor similar to that of the first embodiment is used with a tab terminal which does not undergo chemical polishing as in the present invention.
We made 00 prototypes.

When the same test as in Example 1 was carried out, it was found that there were 12 electrolytic capacitors in which leakage of the electrolytic solution was observed.

【The invention's effect】

In the present invention, since the round bar portion of the tab terminal is chemically polished, the round bar portion has a smooth surface, the fitting property with the inner wall surface of the through hole of the rubber sealing body is improved, and It is possible to prevent leakage of the driving electrolyte solution.

Therefore, it is possible to provide a highly reliable electrolytic capacitor.

[Brief description of drawings]

FIG. 1 is a schematic view showing a tab terminal.

[Explanation of sign]

 1 Tab terminal 2 Round bar part 3 Flat part 4 Leader wire

Claims (1)

[Claims] 1. A tab terminal for an electrolytic capacitor comprising an aluminum round bar portion, a flat flat portion of the same aluminum, and a lead wire welded to the round bar portion, at least the round bar portion being in a chemical polishing bath. A method of manufacturing a tab terminal for an electrolytic capacitor, which comprises immersing in an electrolytic solution for chemical polishing.