JPH06132172A - Manufacture of tab terminal for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent the leaked liquid of an electrolyte by performing chemical polishing or electrolytic polishing of an aluminum wire itself and then machining the polished aluminum wire for manufacturing a tab terminal with a round rod part whose surface is smoothed. 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, an aluminum wire is dipped into an electrolyte for electrolytic polishing or it is dipped into a chemical polishing bath for chemical polishing. The tab terminal is manufactured in this manner by the aluminum wire where the surface is polished, thus improving the engagement with the through hole inner wall surface of a rubber hole sealed body, preventing the internal electrolyte for drive from leaked, and obtaining a reliable electrolytic capacitor since the round rod part of the tab terminal is polished and smoothed.

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 may be further 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 or electrolytic polishing.

The present invention is characterized in that the aluminum wire itself is chemically or electrolytically polished. Then, it is intended to manufacture a tab terminal having a round bar portion whose surface is smoothed by processing the aluminum wire rod thus polished.

In the present invention, after the aluminum wire itself is chemically or electrolytically polished, for example, a part of the wire is crushed to form a flat-shaped flat portion, and the CP wire is formed on the tangential cross section of the round bar portion. The tab terminals can be manufactured by welding.

In electrolytic polishing or chemical polishing, it is preferable to immerse the aluminum wire rod in a bath and process the aluminum wire rod at one time, or to continuously process the aluminum wire rod while transferring it in the bath.

In the case of electrolytic polishing, it is preferable to immerse an aluminum wire rod in a bath, use the same wire rod as an anode, place a counter electrode in the bath, and apply a direct current.

As the solution, (1) HBF ₄ , H ₃ BO
₃ , a solution consisting of HF (Alzac method), (2) H ₂
Solution consisting of SO ₄ , H ₃ PO ₄ , CrO ₃ , and H ₂ O (Battelle method), (3) Na ₂ CO ₃ , Na ₃
Solution composed of PO ₄ and H ₂ O (Prital method), (4) H
Solution consisting of ₃ PO ₄ , H ₂ SO ₄ and CrO ₃ (Tajima method), (5) H ₃ PO ₄ aqueous solution (Nakayama method), (6) HC
lO _4, C etc. ₂ H consists ₆ O solution can be exemplified.

The electrolysis conditions such as liquid temperature, applied voltage and current application time can be appropriately selected.

Also in the case of chemical polishing, it is preferable that the aluminum wire is immersed in the bath for treatment.

As the solution, (1) NaOH, NaNO
₂ , NaNO ₃ , Na ₃ PO ₄ , H ₂ O (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) H ₃ PO ₄ , HNO ₃ , and H ₂ O (Alcoa method).

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

In this way, a part of the aluminum wire rod whose surface is chemically or electrolytically polished is crushed to form a flat flat portion, and the CP wire is welded to the cut surface of the round bar portion to form the tab terminal. Although it can be manufactured, an anodized film can be formed on the aluminum surface of the tab terminal in the present invention.

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, a 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.

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

[Example] <Example 1>

An aluminum wire rod having a diameter of 2.0 mm and a length of 100 m was prepared. Height 0.2-1.0 on the surface
There were many unevenness of μm.

On the other hand, a solution consisting of 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. An aluminum wire is continuously immersed in this electrolytic bath, the same wire is used as an anode, a counter electrode is arranged in the electrolytic bath, and a direct current with a current density of 200 mA / cm ² is applied,
The aluminum wire was electropolished.

The time during which the direct current was applied to the aluminum wire rod located in the bath was 12 seconds.

After electropolishing, 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 aluminum wire was observed, the height of the surface irregularities was 0.01.
It was about 0.03 μm and was smoothed.

A part of the aluminum wire rod whose surface has been smoothed by electrolytic polishing is crushed and cut, and a CP wire is welded to obtain a diameter of the round bar 2.
A tab terminal having a length of 0 mm, a length of 6.0 mm, a flat portion width of 2.5 mm, a thickness of 0.35 mm, and a length of 15 mm was manufactured.

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. Thus, 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.

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 heated 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>

Example 1 was used for the tab terminal fixed to the anode foil.
The same electrolytic capacitor as in Example 1 was manufactured in the same manner as in Example 1 except that an oxide film was formed in the same manner as described above 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 electrolyte leakage. <Example 3>

Chemical polishing was performed instead of the electrolytic polishing in Example 1. Other than that is the same as that of the first embodiment.

Chemical polishing is as follows.

Phosphoric acid 80.5% by weight, nitric acid 3.5% by weight
The aqueous solution of was maintained at a liquid temperature of 90 ± 2 ° C. to form a chemical polishing bath, and the aluminum wire was continuously immersed in this chemical polishing bath for 180 seconds to chemically polish the tab terminals.

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 aluminum wire was observed, the height of the surface irregularities was 0.01.
It was about 0.03 μm and was smoothed.

A tab terminal was manufactured in the same manner as in Example 1, 20,000 electrolytic capacitors similar to those in Example 1 were prepared, and the same tests as in Example 1 were carried out. As a result, no electrolyte leakage was observed. . <Comparative example>

Using the tab terminals which are not subjected to electrolytic polishing or chemical polishing as in the present invention, 20000 electrolytic capacitors similar to those of Example 1 were made as 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 polished to have a smooth surface, the fitting property with the inner wall surface of the through hole of the rubber sealing body is improved, and the internal drive electrolyte solution is improved. It is possible to prevent liquid leakage.

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 (2)

[Claims] 1. A method of manufacturing a 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,
A method for producing a tab terminal for an electrolytic capacitor, which comprises immersing an aluminum wire in an electrolytic bath and electrolytically polishing the aluminum wire to produce the tab terminal from the aluminum wire having an electrolytically polished surface. 2. A method for manufacturing a tab terminal for an electrolytic capacitor, which comprises an aluminum round bar portion, a flat flat portion of the same aluminum, and a lead wire welded to the round bar portion,
A method for producing a tab terminal for an electrolytic capacitor, which comprises immersing an aluminum wire in a chemical polishing bath and chemically polishing the aluminum wire to produce the tab terminal from the aluminum wire having a chemically polished surface.