JPS62219611A - Etcher - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an etching device for continuously etching aluminum foil for electrolytic capacitors.

[Prior Art] Generally, the surface of aluminum foil for electrolytic capacitors is etched in a suitable electrolyte to increase the capacitance.

This etching method is broadly divided into medium-high voltage (medium-high voltage) and low-voltage (low voltage) etching methods depending on the use of the electrolytic capacitor. In particular, for low-voltage etched foils in low-voltage electrolytic capacitors, the finer the unevenness formed by etching, the better. This causes the surface roughening rate to decrease.

Therefore, as an etching device configured to quickly pull up the etching foil from the electrolytic solution after etching, there is already a Japanese Patent Publication No. 42-21410 entitled ``Method for Etching Aluminum Foil for Electrolytic Condenser''. As shown in Fig. 4, this etching device (1) has a pair of carbon electrodes (4) and (5) in an electrolytic cell (3) filled with a suitable electrolyte (2).
) are arranged vertically facing each other, power supply rollers (6) and (7) are arranged outside the electrolytic cell (3), and intermediate rollers (8) and (9) are arranged inside the electrolytic cell (3). The power supply roller (6), (
7) and the carbon electrodes (4) and (5), a power source (10
), the aluminum foil (11) is introduced from the first power supply roller (6) side, and the aluminum foil (11) is introduced from the first intermediate roller ('8) and the second (7)' intermediate roller (9), The carbon electrodes (4) and (5) are passed through the second power supply roller (7).
This is derived from the side. Aluminum in this etching device (1)! Etching (11) starts from the moment the carbon electrodes enter between the lower ends of the electrodes (4) and (5), progresses while moving toward the upper end, and is removed from the electrolytic solution (2). If it happens, it will end. Power sources for etching include AC power, DC power, pulse power, and a combination of these power sources. Also, carbon electrode (4)
, (5) has an insulating plate (1) on its back, bottom or side to prevent excess current from flowing.
2) may also be provided.

[Problem to be solved by the invention 1 Next, when electrolytically etching aluminum foil,
It is well known that when a constant voltage is applied as shown in the figure, the current changes with time as shown in Figure 6. This is because the oxide film formed on the surface of the aluminum foil by natural oxidation increases the interfacial resistance at the start of etching and functions to suppress the flow of current. However, as etching progresses and the oxide film is destroyed, the current increases and converges to a predetermined current.

□ That is, at the start of etching, the current density is lower than the predetermined current density, and this low current density causes the current to concentrate on the aluminum foil, hindering the progress of uniform etching, and eventually causing the rough surface of the etching foil. This is causing a decline in the conversion rate.

Therefore, instead of applying a constant voltage, constant current control is generally performed so that a constant current flows. However, when etching is performed using the etching apparatus (1) shown in FIG. The same phenomenon occurs when the voltage is applied. That is, when a constant current is caused to flow by the constant current control power source (10), the carbon electrodes (4) and (5) as a whole have a constant current. However, aluminum'la (11) is carbon electrode (4), (
5) When moving from the lower end to the upper end, near the electrolyte (2,) surface (Z) between the carbon electrodes (4) and (5)
and near the middle of carbon electrodes (4) and (5) (Y),
The aluminum foil (11) located at 1 has been sufficiently etched, there is almost no oxide film, the interfacial resistance is high, and current flows easily. In contrast, the aluminum foil (11) located near the lower ends of the carbon electrodes (4), (5) (1)
5) Immediately after entering the gap, there is high interfacial resistance,
Current is becoming difficult to flow. Because of this, as shown in FIG. 7, the current density is non-uniform in the length direction of the aluminum tray (11) located between the carbon electrodes (4) and (5). The current density curve shown in FIG. 7 and the current curve shown in FIG. 6 are very similar.

As can be seen from this, the starting point of etching (X)
The current density is significantly lower than the predetermined current density, and the low current density causes current concentration, which hinders the progress of uniform etching. , shi, then,
Conventionally, it has been impossible to obtain an aluminum electrode foil for electrolytic capacitors having the desired high surface roughening ratio.

[Means for Solving the Problems] However, the present invention makes it possible to obtain an aluminum foil for electrolytic capacitors having a high surface roughening rate by increasing the current density at the start of etching to a predetermined value. The purpose of the present invention is to provide an etching device, specifically a pair of facing etching devices.

□ At the opposite positions of the lower ends of each electrode. It has a mountain part.

[Example] Hereinafter, an etching apparatus (IA) according to the present invention will be described! The explanation will be based on Figures 1 to 3. ・Prior to the explanation, please refer to Figure 4.
Six parts that are the same as those in the conventional example shown in the figure are given the same reference numerals, and in the present invention, only particularly improved parts will be explained.

As shown in Figure 1, a pair of carbon electrodes (4) and (5)
) are provided with protrusions (41) facing each other in order to raise the current density at the start of etching to a predetermined value.
, (51) are formed. These protrusions (41), (51)
are formed integrally with the carbon electrodes (4) and (5) or as a separate structure. The shapes of the protrusions (41) and (51) are as follows:
Various shapes can be exemplified, such as a triangular shape as shown in FIG. 1, a rectangular shape as shown in FIG. 2, and a trapezoidal shape as shown in FIG. 3.

The distance <a> between both carbon electrodes (4) and (5) and the distance (b) between both guide portions (41) and (51) vary depending on the etching conditions, but for example, an aluminum foil with a thickness of 100 μm ( 11) Current density 400 mA/Cm
In the case of etching with ``Distance (a)'', distance (a) may be 50 mm, and distance (b) may be 15 mm.

Next, we will discuss specific etching and its effects.

The composition of the electrolytic solution (2) is Hc (2 is 0.5 pa, A
I2c II s is 0.5M% H2SO4 is 0.05
M, 'H, PO4 are 0.5M, the liquid temperature is 6o℃, the current density is 400mA/cm2, and the purity is 91.99%.
1m (11) of aluminum is etched. next,
The etched aluminum foil (11) is chemically converted with an ammonium adipate aqueous solution by applying a voltage of 50V. Table 1 shows a comparison between the capacitance and bending strength of the chemically formed foil (Example) manufactured in this way and the conventional example.

Example 1 uses the carbon electrodes (4) and (5) shown in FIG.
Example 2 is shown in FIG. 2, and Example 3 is shown in FIG. 3.

The conventional example was obtained using the conventional etching apparatus shown in FIG. 4 under the above-mentioned etching conditions and chemical formation conditions.

As can be seen from Table 1, the etching foil manufactured according to the present invention has a higher capacitance and a higher bending strength than the conventional example.

[Effects] As described above, in the present invention, since the protrusions are formed at opposite positions of the lower ends of each of the pair of oppositely facing carbon electrodes of the etching device, it is difficult to start etching the aluminum foil as in the conventional method. This makes it possible to prevent uneven melting of the aluminum foil at this point. Therefore, it is possible to provide an etching foil having a high surface roughening rate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an etching apparatus according to the present invention, FIGS. 2 and 3 are diagrams showing other shapes of carbon electrodes, and FIG.
The figure shows a conventional etching apparatus, Fig. 5 shows applied voltage characteristics, Fig. 6 shows current characteristics, and Fig. 7 shows aluminum foil and carbon electrodes in the etching apparatus shown in Fig. 4. It is a figure which shows the relationship of the current density in the length direction between. In the figure, (1), (IA)... etching device, (
2)... Electrolyte solution, (3)... Electrolytic cell, (
4), (5)... Carbon electrode, (6), (7), (
8), (9)...roller, (10)...power supply,
(11)...aluminum foil, (12)...
- Insulating plate, (41). (51)...Protrusion. Patent applicant Elnor Co., Ltd. Figure 5 Clear T Figure 61 Figure 7 □

Claims (1)

[Claims] (1) A pair of carbon electrodes is installed vertically in an electrolyte bath filled with an electrolytic solution, and an aluminum foil is introduced from the gap between the lower ends of both carbon electrodes to start etching. What is claimed is: 1. A continuous etching apparatus which finishes etching at the end of the etching process, characterized in that protrusions are formed at opposing positions of the lower ends of both carbon electrodes.