JPS638763Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an etching device for electrode foil for electrolytic capacitors using alternating current, and the purpose of this invention is to reduce the variation in etching magnification in the width direction of aluminum foil by improving the electrode structure. That is.

Conventionally, when etching aluminum foil for electrolytic capacitors by applying alternating current, the electrode structure was such that a pair of electrodes were placed on both sides of the running aluminum foil, and grooves were formed to allow both ends of the running aluminum foil to pass through. He was wearing a mask. The mask is preferably made of a processed acid-resistant resin plate, and both ends of the aluminum foil passed through the grooves of the mask are preferably not etched. This is to maintain the strength of the aluminum foil when cutting in the width direction in a subsequent process. However, the current fed between the two electrodes is affected by the etching condition due to the small gap between the masks attached to the two electrodes and the rapid rise of a considerable amount of gas generated between the aluminum foil and the electrode during etching. The gas flows to the counter electrode through holes provided in the mask for gas escape to avoid adverse effects. Since this leaked electrode does not act at all on the aluminum foil located between the two electrodes, it causes variations in the current value, and thus causes variations in the etching magnification. This kind of variation in etching magnification is
When measuring the capacitance of a 500 mm wide aluminum foil in 10 mm increments in the width direction, the maximum/minimum value was 1.15 to 1.20.

The present invention has been developed in view of the above points, and its purpose is to reduce the variation in etching magnification in the width direction of aluminum foil.

Examples will be described below with reference to the drawings. As shown in FIG. 1, the aluminum foil 1 is run with both ends inserted into the mask 5 provided between the electrodes 2, 3, 4 connected to an AC power source, and the bottom roller 6 When it reaches this point, it turns around and runs while being sandwiched between the mask 7 provided between the electrodes 3 and 4. Note that 8 is an etching solution and 9 is an etching tank. The masks 5 and 7 are attached to the inner wall of the etching tank 9,
For example, insulation and heat resistance such as trifluoroethylene,
It is made by bending a thin sheet with excellent acid resistance and flexibility, and its plane is as shown in Figure 2. Therefore, as is clear from FIG. 2, the aluminum foil 1 is sandwiched between the flexible masks 5 and 7 and travels in close contact with them, so that both ends sandwiched between the masks 5 and 7 are etched. Furthermore, there is no leakage of current between the electrodes 2 and 3 and between the electrodes 3 and 4 connected to the AC power source, and the current acts on the aluminum foil running in between, and almost never flows to the counter electrode. Therefore, the supplied current has characteristics that can be effectively used for etching. Furthermore, the aluminum foil 1 may meander while running, but since the etching device of the present invention uses a flexible sheet, it follows the meandering of the aluminum foil 1. never leaves Masks 5 and 7,
Therefore, the fed current will not leak.
The results of etching aluminum foil using such an etching device will be described below. The etching equipment shown in Figures 1 and 2
Aluminum foil of 90μm x width 500mm, Hcl 20wt/v%
+H ₂ SO ₄ 2wt/v% aqueous solution (liquid temperature 35°C) in an etching solution with a current density of 10A/dm ² and a quantity of electricity.
It is run under conditions of 6000C/dm ² to perform alternating current etching, then washed and dried. Remove this etched foil by 10mm from both ends in the width direction to make it 480mm.
This was divided into 48 equal parts, 48 samples with a length of 50 mm were collected from a width of 10 mm, and these samples were
Current density in 5wt/v% aqueous solution (liquid temperature 60℃)
Figure 3 shows the capacitance of each sample obtained when the voltage was increased to 49 V at 2 A/dm ² and then the current was decreased for 20 minutes while keeping the voltage constant. The arrangement of the samples in FIG. 3 is the same as the position when etched. Further, similar results of a conventional example corresponding to this are shown in FIG. In this conventional example, the groove of the mask is
mm, thickness 90μm x width passed through the groove
This is a 500mm aluminum foil with 10mm removed from each side. As is clear from these results, when aluminum foil is sandwiched between flexible masks 5 and 7 using the device of the present invention, the corrosive current is used to etch the aluminum foil 1 without leaking. Therefore, the maximum/minimum variation in capacitance in the width direction is 4.1%. On the other hand, the results in Figure 4 are extremely low at both ends, and the variation is maximum/
The minimum is 25.9%, and even when excluding both ends
The variation is 8.5%, which is twice as large as that of the present invention. In this conventional example, the grooves of the mask are 1 mm, so even if a 90 μm thick aluminum foil is passed through, there is a gap between the grooves of the mask (although the etching solution is present), and the fed current leaks through the gap, so both ends are thought to be extremely low. However, this total width of 20 mm with 10 mm on each side corresponds to 4.2% of the area, and even if these 20 mm are removed, there will be twice as much variation as in the present invention, and the remarkable effect of the etching apparatus according to the present invention is It shows.

As mentioned above, in the etching device for electrode foil for electrolytic capacitors according to the present invention, the aluminum foil is sandwiched between flexible masks and run.
Since there is no leakage of the fed current, there is little variation in the etching magnification in the width direction, and since a flexible mask is used, even if the aluminum foil meanderes, the mask will follow and the contact between the mask and the aluminum foil will be reduced. This has the advantage of not creating any gaps between them.

In the above example, the case where trifluoroethylene was used as a flexible mask was described, but for example, trifluorochloroethylene, vinylidene fluoride, vinylidene chloride, tetrafluorohexafluoropropylene, polypropylene, polyethylene could be used. Similar effects can be obtained by using

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional perspective view showing the etching apparatus of the present invention, Fig. 2 is a partial plan view of the etching apparatus shown in Fig. 1, and Fig. 3 is a partial cross-sectional view of the etching apparatus of the present invention. FIG. 4 is a curve diagram showing variations in the width direction of the etching foil obtained using the conventional etching apparatus. FIG. 1... Aluminum foil, 2, 3, 4... Electrode, 5, 7
...Mask, 6...Bottom roller, 8...Etching liquid, 9...Etching tank.

Claims (1)

[Claims for Utility Model Registration] (1) An etching tank having electrodes and an etching solution connected to an AC power supply, and a flexible film attached to the inner wall of the etching tank and sandwiching both ends of the electrode foil running between the electrodes. 1. An etching device for electrode foil for electrolytic capacitors, which is equipped with a mask made by folding a thin sheet with a high temperature. (2) Utility model registration claim No. (1) characterized in that the mask is made of ethylene trifluoride, ethylene trifluoride chloride, vinylidene fluoride, vinylidene chloride, propylene tetrafluoride hexafluoride, polypropylene, and polyethylene. The etching device for electrode foil for electrolytic capacitors as described in item ).