JPS5983772A - Etching method of aluminum foil - Google Patents

Abstract

PURPOSE:To easily obtain an etched foil excellent in mechanical strength without reducing its surface-enlarging magnification, by performing the treatment of etching an Al foil useful as the electrode of a capacitor while applying many fine lines onto the surface of said foil. CONSTITUTION:Many fine lines 2 resistant to corrosion are applied onto the surface of an Al foil in parallel with each other, for instance, along the logitudinal, i.e. rolling, direction of the foil 1, and the etching treatment is performed under this condition. Hence, an etched surface having many deep rugged parts where a dissolution amount is large is formed on the surface part onto which the lines 2 are not applied, while an etched surface having many shallow rugged parts where either dissolution is not brought about or a dissolution amount is small is formed on the part onto which the lines 2 are applied. By this constitution, tensile strength along the rolling direction of the foil and bending strength along a direction perpendicular to said rolling direction are made large.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to tensile strength and bending strength [Example 11, Etched foil that can avoid noises such as cutting during the spring-warming process of capacitor elements. This article relates to an etching method for aluminum foil.

As is well known, the aluminum foil used for the electrodes of electrolytic capacitors is coated with a surface layer to increase surface area magnification. L: Corrosive etching treatment is performed.

However, mechanical strength such as tensile strength and bending strength of the aluminum foil after being etched decreases due to the stress on the capacitor element. 3, there are inconvenient problems such as cutting the terminal at the part or core part,
Researchers of etching methods are currently struggling to determine whether it is possible to obtain a large plate surface magnification without using extremely strong aluminum foils.

In view of this point, the present invention was also successful in developing an etching method that can easily obtain an etching foil that has excellent mechanical strength without reducing its magnification and magnification. The etching method is proposed, and the four main features are that a large number of thin lines L:MfJ that resist corrosion are formed on the surface of the aluminum foil, and then the etching process is performed. A large number of fine wires are applied to both the front and back surfaces of the aluminum foil to be treated, or to one side thereof, to resist corrosion and delay the onset of corrosion.
By performing etching treatment in this state, a corroded surface with a large number of deep irregularities with large molten steel is formed on the long and sharp parts of the thin wire, and the fine wire is also
Hardly dissolves〃1 Or shallow unevenness with few dissolving needles? The purpose is to form an etched foil having a large number of corroded surfaces, and to obtain an etched foil having excellent mechanical strength without compromising the overall area expansion.

Fine wire that resists corrosion? There are various methods for applying the coating, but the simplest method is the printing method.Most printing inks have poor resistance to corrosive liquids and slow the progress of corrosion. There are two methods of applying oxidized fine wires to η, such as applying heat using a laser beam, and applying pressure using rollers. The oxide resists corrosion, and the latter resists corrosion due to changes in the aluminum structure due to changes in pressure. After etching, this corrosion-resistant thin wire is
Also, there is no effect of leaving strong parts such as auxiliary cylinders in the etched foil, and as a result, the aluminum foil after etching has excellent mechanical strength.

The width, spacing, arrangement, etc. of the thin wires are selected as appropriate in relation to the setting of the wavefront magnification and mechanical strength. (21 is shown in Fig. 7 in which it is formed in a purple parallel shape. With this structure, the tensile strength in the rolling direction and the bending strength in the direction perpendicular to the rolling direction are increased, and therefore, it is usually wound around a capacitor. Since the electrode foil is cut into strips of the required width in parallel to the rolling direction, it is most preferable as a thin wire k/flj configuration on the aluminum foil.

Figure 2 shows a large number of thin 11i1jl on aluminum foil (1).
(Figure 3 shows the case in which the aluminum foil (1) is applied in an X-shaped manner, with a large number of thin lines (21) intersecting each other in an X-shape, and this configuration σ). too,
It has excellent tensile strength and bending strength.

Furthermore, Figure 4 shows a large number of thin lines (
21 is shown in the configuration when it is applied in a parallel manner. In this configuration, it is effective to obtain aluminum foil (11 sheets of aluminum foil by cutting it to the required width in a direction perpendicular to the rolling direction). be.

Figures 5 (a) and (b) show two enlarged cross-sectional views of the aluminum foil after etching. ,−
! Figure (b) shows the result when 21 lines (21 lines) are applied to both sides of the aluminum foil (1).

By the way, applying aJ 1111'c, which resists corrosion, gives the impression that the surface expansion ratio of the aluminum foil, which cannot be obtained if it is not applied, is reduced at first glance, but the experimental results It was found that there was almost no difference in capacitance ratio.

The reason for this is that the proportion occupied by the thin wires is only a few percent of the total ifD product, and that the amount of corrosion and dissolution reduced in the Toda line can be compensated for by other parts without thin wires. It is thought that it depends on the situation. Sweet #11 line? Assuming that the amount of corrosion and dissolution of aluminum when applying fine wire is the same as the amount of corrosion when fine wire is not applied, the average cross-sectional area of the part that remains uncorroded is equal to y, so the mechanical strength However, according to the results of experiments, it was found that there was a significant difference in mechanical strength.

The reason for this is that the areas where the fine wires are not coated are deeply corroded.
Therefore, it is thought that this part is fragile and easily cracks, and is likely to be damaged due to the cross-sectional area of the nest.

Next, the example will be explained in detail.

Sample 1 An annealed aluminum foil with a thickness of 100 μm and a purity of 99.99% was etched using a commonly used electrolytic etching foil in a chloride solution, so that the etching temperature was approximately 38%. Sample 2: Sample 2: Sample 2: After being washed with water and chemically treated in borium e-liquid at 375 V&C
mm1W] Im, with a thin line made with magic ink of 0.25 mm width parallel to the rolling direction of aluminum foil on one side Sample 3 Sample 2 with thin lines made on both sides Sample 2
The capacitance was measured using an electric bridge in the electrolytic solution to obtain the equivalent column capacitance, and the μZa value was calculated by multiplying the area (d) by 2 to the Tfi.

In addition, the tensile strength was measured at a length of 10cm parallel to the rolling direction.
fn, tensile force in the rolling direction for etching foil cut into slits with width lα? The total tensile force is increased at a rate of 0.25~ per second to obtain 911 fk at the time of break.

Its tensile strength Wcm 11 was calculated. Furthermore, regarding the bending strength, a sample r identical to the tensile strength measurement sample described above was bent at an angle of 45 degrees with respect to its length direction, the bending surface at this time had a radius of curvature of 1IIIi1+, and a tensile force of 250 g was applied in the length direction. In addition, the bending method is to first bend it at a 45 degree angle, return it to its original position, then extend it 45 degrees in the opposite direction, and then sweep it back to its original position. The number of times it was cut was calculated. The results are as follows.

Storage capacity μshi4 Tensile strength % For bending strength sample 1
0.72 1% 23 Sample 2 0.7
2 1.5 For 10 samples 3 0.7
1 1% 8 19 Experimental results mentioned above)
As can be seen from the above, according to the present invention, even though the weight and weight are the same, the obtained mechanical strength is very large, especially the bending strength. It is understood that this is extremely advantageous for winding of capacitor elements and handling of VC using an automatic winding machine.

In addition, as a result of several experiments, if I/c↓, as mentioned earlier, is there a thin line due to printing? It has been learned that this method is the most effective and practical, and that the printing ink used in this case, whether water-based or oil-based, does not provide sufficient effects. The inventor thought that it would be necessary to apply a thick coat of extremely strong corrosion-resistant ink to create fine lines on the aluminum foil.

According to the experimental results, the ink has extremely low corrosion resistance.
Even a thin line of threat was quite effective. Corrosion progresses slowly at the beginning, but progresses rapidly in the early stages, and the fine lines that have not been applied with the ink should not be washed away before the corrosion progresses in earnest. It is thought that this is because the corrosion of the parts has finished and it is too late.

[Brief explanation of drawings]

1 to 4 are partial plan views of etching foils in embodiments of the present invention, and FIG. 5 is an enlarged sectional view of the etching foils. In the figure, (1) is an aluminum foil, and (2: is a thin line).

Claims (1)

[Scope of Claims] (11 Performing the entire etching process after applying a large number of fine wires to resist Ui corrosion on the surface of the aluminum foil? A method for etching aluminum foil characterized by: (21i 11i1J Th-Rolling of aluminum foil (3) The method of etching aluminum foil according to claim 1, which is performed in parallel to the rolling direction of the aluminum foil. Aluminum? A method for etching aluminum foil according to claim 1, 2-i or 3, wherein the wire r is flowed onto both sides of the aluminum foil.