JPS61221400A - Method for controlling electroplating deposition - Google Patents

Abstract

PURPOSE:To maintain uniformly the plating deposition in a transverse direction by measuring the plating deposition, etc. at the transverse points corresponding to each of plural electrodes and controlling independently the plating current of the electrodes so that the measured values attain the common target value. CONSTITUTION:The electrode 1 is formed of the divided electrodes 11, 12, 12'-19, 19' which are divided in the transverse direction and are insulated. These electrodes are connected electrically to current control devices 21-29. The current of the same value is passed to the divided electrodes 12'-19' in the symmetrical positions as well. The coating weight or plating current density in the transverse direction of a strip is actually measured, upon starting of plating, in accordance with the positions of the electrodes 11-19 or 11-19'. The ratios between the actually measured values and the coating weight in the central part in the transverse direction corresponding to the electrode 11 are determined and are fed back to the coating weight control device. The current controlled variable in the transverse direction is calculated by said control device and commands are emitted to the devices 21-29 so that the current values in the electrodes 12-19' attain the intended set values. Each coating weight in the transverse direction of the strip is thereby made to coincide with the target value.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method for controlling the amount of electroplating deposited in the electroplating of a metal plate to make the amount of plating deposited uniform in the width direction.

<Prior art and problems> For example, in the electroplating of strips, integrated electrodes (insoluble electrodes) are provided on the front and back sides of the strip passing through a bath. When a crack occurs, there will be parts where the distance between the electrode and the strip becomes narrower and parts where it becomes wider in the width direction, and current will flow easily in the narrow part and difficult in the wide part, so the current will not flow in the width direction. The density changes, which causes the amount of plating to vary in the width direction.The problem is that the uniformity of the amount of plating in the width direction is lost due to warping of the strip, and if this exceeds the allowable limit, the product becomes defective. There is a point.

Although various proposals have been disclosed as methods for preventing the above-mentioned accidents, there is still no method that can achieve a definitive preventive effect. Therefore, in the prior art, variations in the amount of plating deposited in the width direction are generally unavoidable, and the variations are extremely large.

An object of the present invention is to provide a method for controlling the amount of electroplating that can maintain a uniform amount of plating in the width direction, regardless of the presence or absence of a crimp in the width direction of the strip.

<Means for Solving the Problems> The present applicant previously filed an application for an electroplating apparatus in Japanese Utility Model Application Publication No. 167773/1983. This device has a structure in which the anode is divided in the direction of the plate crest, each divided anode piece is energized independently, and an insulating shield plate is completely interposed between adjacent divided anode pieces. The purpose of this method is to obtain plated products with various special shapes in which the thickness of the plating differs locally in different directions, or where there is no plating locally.

The control method of the present invention is such that the board is divided in the width direction and! By using a plurality of electrically insulated electrodes, the amount of plating deposited is made uniform in the width direction.

That is, in the present invention, when performing electroplating using a plurality of electrodes that are divided in the width direction and electrically insulated, the amount of plating deposited or the plating current at a plurality of locations in the width direction is adjusted corresponding to each of the electrodes. The method is characterized in that the amount of plating deposited is made uniform in the width direction by actually measuring the density and independently controlling the plating current of each of the electrodes so that each measured value agrees with a common target value for each of the plurality of locations. The gist of this paper is a method for controlling the amount of electroplating.

Hereinafter, the method of the present invention will be explained in detail based on the drawings.

Fig. 1 is a sectional view showing an example of a continuous electroplating apparatus for carrying out the method of the present invention, Fig. 2 is a front view illustrating the structure of an electrode divided in the width direction used for carrying out the method of the present invention, and Fig. 3 1 is a system diagram showing an example of a control system when implementing the method of the present invention using the equipment shown in FIGS. 1 and 2. FIG.

In the vertical continuous electroplating apparatus shown in FIG.
21 into the plating solution (3), descend, change the direction upward with the energized roll (4), rise, and during this rise and fall, are vertically arranged in pairs on the left and right with the threading line in between. The electroplating current ffl (11 (11) and (11 (11)) is electroplated by the plating current from (11), and exits the tank (2) through the turn-up roll (6) on the exit side.

As shown in the front view of FIG. 2, the electrode (1) is a divided electrode α1)Q2(12) divided in the width direction and electrically insulated.
...... αI (19) In the illustrated example, there are divided electrodes of a prescribed width (
(a) - ridges and (12) - (19) are provided symmetrically. Split electrodes (a) and (12) in symmetrical positions...
. . . 0 and (19') are electrically connected.

Then, the division is set to the pole αD02...α电 is electrically connected to the corresponding current control device 31) to the wire, and the same value is applied to the division chambers 1(12)...(19) located at symmetrical positions. It is configured to allow a current to flow through it. This takes advantage of the fact that the warpage of the stop appears symmetrically,
Current control device M31)...This is an effective structure for simplifying the structure of the wire.

In the illustrated example, each divided electrode is only electrically insulated, but if the uniformity of the amount of plating in the width direction is to be made even more strict, it is possible to 5
It is also possible to provide a shielding plate between each divided electrode as in Japanese Patent No. 7-167778.

In Figure 3 showing the control system, (7) is the amount of plating (
0]) is a width direction basis weight control device that controls the basis weight of each divided section in the width direction; This is a width direction date measurement device that measures the date amount in the direction. The width direction date measurement device is used in ordinary plating equipment where multiple tanks are connected in series to form one unit.
It is generally installed on the exit side of the final plating tank on the winding side. As the basis weight measuring device (2), there is one that uses fluorescent X-ray analysis.

The method of controlling the basis weight in the width direction of the present invention using the above device is performed as follows.

Prior to electroplating, the total basis weight control device (7)
For the width direction date amount control device 61), the current required to achieve the target date amount (common to each part) for each of the ~θ electrodes α (shown in FIG. 2) divided in the width direction. value(
Output f/) ~ (f?) (initial setting value) (
(indicated by a in Figure 3).

When electroplating is started, first, the date amount in the width direction of the plated strip is measured by the width direction measurement device G2 using the dividing electrode αη~(19 or (12) of 0℃α)...
・Actually measure corresponding to position 09 (19). Then,
The width direction date amount ratio (kz) ~ (kV) between these measured values and the basis weight of the width direction central part (portion corresponding to the electrode α]) is calculated, and the width direction date amount ratio (kz) ~ (kp ) is fed back to the width direction basis weight control device G1) (indicated by arrow °C in FIG. 3). The width direction basis weight control device Gl) uses the following 0 formula based on the initial setting value (f/) to (fP) of the plating current and the width direction basis weight ratio (kz) to (kV) fed back above. calculate the width direction current control amount (f/) to (f), and set the current control device e21) so that the current value in each divided electrode becomes the initial setting value (f/) to (f2). ~ Give orders to Kan.

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■After that, by repeating the same calculation based on the new measured value of the coating weight and controlling the current value in the strip width direction, each coating weight in the width direction of the plated strip is made to match the target value, and the date Make the amount uniform across the width.

In the above explanation, the actual measurement value of the width direction weight of the plated strip was used as the feedback signal, but instead of this, the width direction current value 1 which flows between the strip and each electrode was used.
It is also possible to perform the same control as described above based on the ratio between these and the current value flowing through the electrode at the center in the width direction.

<Example> Next, examples of the method of the present invention will be described.

Using the apparatus shown in FIGS. 1 to 3 and under the conditions shown in Table 1, strips were electrolytically plated with Zn by controlling the basis weight in the width direction according to the method of the present invention. Further, for the sake of stability, similar electrolytic Zn plating was performed without controlling the basis weight in the width direction.

Fig. 4 (conventional example) and Fig. 5 (invention example) show the investigation results of the deviation in the amount of Zn deposited in the width direction of each plated strip in the conventional example without width direction date amount control and the example of the present invention in which this was done. ).

As is clear from both figures, the variation in the Zn deposition amount in the width direction, which ranged to ±IOX in the conventional example, was suppressed to ±3% or less by implementing the method of the present invention.

It can be seen that the variation in the amount of Zn deposited in the width direction observed in the conventional example is mainly caused by warpage of the strip, since the front and back surfaces of the strip show a symmetrical relationship.

If the variation in the width direction of the amount of ZN deposited on the plated strip is kept to the level of the example of the present invention, the incidence of defective products can be greatly reduced.

<Effects of the Invention> As is clear from the above explanation, by applying electroplating to a strip using the control method of the present invention, it is possible to maintain a uniform amount of plating in the width direction regardless of warpage in the width direction. can. Therefore, the method of the present invention can save many plated products that have conventionally become defective due to large fluctuations in the amount of plated coating in the width direction.
This will greatly contribute to improving quality and productivity and reducing costs in the production of electroplated strips.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of an electroplating apparatus for implementing the method of the present invention, and FIG. 2 is a plane view showing an example of the electrode surface facing the strip of electrodes divided in the width direction used for implementing the method of the present invention. 8 is a system diagram showing an example of a control system when implementing the method of the present invention using the equipment shown in FIGS. 1 and 2. FIG. FIG. 5 is a graph showing the deviation of the amount of Zn deposited in the width direction in electroplating according to the method of the present invention. 1: electrode, 2: plating tank, 8: plating solution, 4: energizing roll, 5: turndown roll, 6: turn-19: split electrode, 21 to 29: current control device, 30: overall area weight control device, 31: Width direction basis weight control device, 32: Width direction basis weight measurement device. Ryo Ganjin Sumitomo Kinkyo Industries, Ltd. 1.1.Representative Patent Attorney: Gen 1;253,Children-De-Representative Patent Attorney Yoshi 1)Sho 29. Fig. 3 Fig. 4 WI Fig. 5 O tile width 1 mm (mm)

Claims (1)

[Claims] (1) When performing electroplating using multiple electrodes that are divided in the width direction and electrically insulated, the amount of plating deposited or the plating current density at multiple locations in the width direction is determined corresponding to each of the electrodes. The method is characterized in that the amount of plating deposited is made uniform in the width direction by controlling the plating current of each of the electrodes independently so that each actual measurement value coincides with a common target value for each of the plurality of locations. Electroplating coating weight control method.