JPH06132173A - Manufacture of tab terminal for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To smooth a round rod part and to improve the engagement with the through hole inner wall surface of a rubber hole sealed body by performing electrolytic polishing and chemical treatment of the round rod part of a tab terminal. CONSTITUTION:A tab terminal 1 for electrolytic capacitor consisting of a 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 manufactured. Then, the flat part 3 and the round rod part 2 of the tab terminal 1 are dipped into an electrolytic bath and are subjected to electrolytic polishing and then the flat part 3 and the round rod part 2 are dipped into a formation bath containing 3 wt.% aqueous ammonium adipate maintained at 85 + or -1 deg.C for performing formation treatment, thus smoothing the surface of the round rod part, preventing the electrolyte for drive inside the through hole of a rubber hole sealed body from 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 CP wire (copper-coated steel wire), and the surface thereof may be 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 electrolytic polishing.

In the present invention, not only the round bar portion of the tab terminal is electrolytically polished, but also the flat portion can be simultaneously electrolytically polished to remove burrs from the flat portion.

In electrolytic polishing, the flat portion and the round bar portion of the tab terminal are immersed in an electrolytic bath, the lead wire serves as an anode, the counter electrode is arranged in the electrolytic bath, and a direct current is applied. Preferably.

As the electrolytic solution, (1) HBF ₄ , H ₃ B
Solution consisting of O ₃ and HF (Alzac method), (2) H
₂ SO ₄ , H ₃ PO ₄ , CrO ₃ , H ₂ O solution (Battelle method), (3) Na ₂ CO ₃ , Na ₃
Solution composed of PO ₄ and H ₂ O (Prital method), (4) H
₃ PO ₄ , H ₂ SO ₄ , CrO ₃ solution (Tajima method), (5) HClO ₄ , C ₂ H ₆ O solution,
(6) H ₃ PO ₄ aqueous solution (Nakayama method) and the like can be exemplified.

The electrolysis conditions such as liquid temperature, applied voltage, current density, and current application time can be appropriately selected. In the present invention, the aluminum anodized film can be formed by subjecting the aluminum surface of the tab terminal to chemical conversion treatment. This oxide film is preferable because it can improve the corrosion resistance of the tab terminal with respect to the driving electrolyte.

For example, in this anodizing treatment, the flat portion and the round bar portion of the tab terminal are immersed in a chemical conversion bath, the lead wire serves as an anode, the counter electrode is arranged in the chemical conversion bath, and a DC voltage is applied. It is preferably treated.

Examples of the chemical conversion liquid include boric acid-based aqueous solutions, phosphoric acid-based aqueous solutions, adipic acid-based aqueous solutions, phthalic acid-based aqueous solutions, and non-aqueous chemical conversion solutions using ethylene glycol and the like.

Further, the chemical conversion conditions such as liquid temperature, applied voltage, current density, and voltage application time can be appropriately selected.

[Example] <Example 1>

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, a solution containing 20% by weight of perchloric acid and 80% by weight of ethyl alcohol was maintained at a liquid temperature of 6 ± 1 ° C.
It was used as an electrolytic bath. The flat part and the round bar part of the tab terminal are immersed in this electrolytic bath, the lead wire serves as the anode, the counter electrode is arranged in the electrolytic bath, and a direct current with a current density of 200 mA / cm ² is applied for 6 seconds. Was electrolytically polished.

After electrolytic 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.

Next, a 3 wt% ammonium adipate aqueous solution was maintained at a liquid temperature of 85 ± 1 ° C. to form a chemical conversion bath. The flat portion and the round bar portion of the tab terminal were immersed in this formation bath, the lead wire was used as an anode, the counter electrode was placed in the formation bath, and a DC voltage of 150 ± 1 V was applied for 50 minutes.

After the anodizing treatment, it was washed with water. In this way, the tab terminals having the aluminum oxide film formed on the flat portion and the round bar portion were fixed to the anode foil and the cathode foil, and the anode foil, the cathode foil and the separator paper were interposed to form a capacitor element.

When the surface of the round bar portion of the tab terminal after chemical formation was observed, the height of the irregularities on the surface was 0.01 to 0.0.
It was 3 μm.

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. and 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>

Example 1 was used for the tab terminal fixed to the anode foil.
The same electrolytic capacitor as in Example 1 was used, except that an oxide film was formed by a chemical conversion treatment in the same manner as in Example 1 and a tab terminal fixed to the cathode foil was not subjected to a chemical conversion treatment. I made a prototype.

When the same test as in Example 1 was carried out, there was no electrolyte leakage. <Comparative example>

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

When the same test as in Example 1 was carried out, it was found that the electrolytic solution leaked was 12 electrolytic capacitors.

【The invention's effect】

In the present invention, since the round bar portion of the tab terminal is electrolytically 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. An electrolytic capacitor tab terminal for an electrolytic capacitor comprising a round bar of aluminum, a flat flat part of the same aluminum, and a lead wire welded to the round bar, and the round bar is electrolyzed. A method for producing a tab terminal for an electrolytic capacitor, comprising immersing the flat portion and the round bar portion in a chemical conversion bath after immersing in a bath and performing electropolishing to perform chemical conversion treatment.