JPS6151040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-speed plating method in radial cell electroplating, and in particular, a means for accelerating the flow of plating solution is provided in the down-pass strip entry side gap. We propose a method that prevents the flow velocity from decreasing and enables high-speed plating.

In general, a feature of electroplating using the radial cell method is that the distance (gap) between the strip and the anode can be made small, resulting in less voltage drop and lower power costs. However, when increasing the speed at which the strip passes, it is necessary to supply a sufficient amount of plating liquid, which inevitably causes the problem that the speed of the liquid flow within the gap must be increased. In this case, if the liquid flow slows down and the supply of plating liquid cannot keep up, the ion concentration of the plating metal on the cathode (strip) surface will become diluted, and _H2 will be generated, causing discoloration on the strip surface. It turns out.

However, in the case of a normal radial cell method, there is a significant difference in the flow velocity of the plating solution in the gap between the down-pass side, where the liquid flows in the opposite direction to the strip passing direction, and the up-pass side, where the liquid flows in the same direction. can. In this way, when there is a difference in liquid flow rate between the down-pass side and the up-path side, the down-pass side, where the flow rate is low, becomes rate-limiting and the critical current density decreases, making it impossible to operate the line at high speed.
Of course, this problem can be solved by making the flow rates on the down-path side and the up-path side equal. For example, if the distance (gap) between the anode and cathode is increased, the difference in flow rate due to strip movement will be reduced. just,
When the gap is increased, the voltage drop becomes large, which has the disadvantage of making it impossible to dissipate the power, which is one of the characteristics of the radial cell system.

Therefore, in this invention, the line speed is restricted to the side with the smaller flow rate by making the flow rates equal on the down-pass side and the up-pass side while keeping the gap at 5 to 15 mm, which is the minimum width according to industrial standards. This method solves the drawback of the prior art of receiving the data. The gist of the structure is that a plating liquid is added to the gap near the inlet side, which becomes the down pass, to accelerate the liquid flow, or a plating liquid is added to the gap near the exit side, which becomes the up pass, to slow down the liquid flow. The feature is that high-speed plating processing is performed by adding a liquid. The details of the configuration will be explained below.

FIG. 1 of the drawings shows a radial cell type electroplating equipment showing one embodiment of the present invention, in which a strip is attached to the outer circumference of a rotating drum for current application and runs synchronously with the rotation of the drum. This method performs plating by applying electricity between the anode and the anode provided with a gap in the radial direction through a plating liquid introduced into the gap from below the anode. In the figure, 1 is a plating tank, 2 is a rotating drum called a conductor roll installed in the plating tank 1, and 3 is a segment-shaped drum arranged around the rotating drum 2 with a wide gap 4 interposed therebetween. The plating liquid 6 is introduced into the gap 4 from the lower end of the anode 3 through the main pipe 5. On the other hand, the strip 7 passes through a deflector roll 8, changes direction, is wrapped around the rotating drum 2, is plated in contact with the plating liquid 6 in the gap 4, and passes through another deflector roll 8' to the next process. Served.

The plating liquid 6 is usually supplied by a pump 9 between the strip 7 and the anode 3 through the main pipe 5, and fills the gap 4. The plating liquid 6
overflows from the upper end of the down path side corresponding to the input side of the strip 7 and the upper end of the up path side corresponding to the exit side of the strip 7, respectively, and accumulates in the plating tank 1. The amount of overflow is
As shown in FIG. 2, on the down path side D, the amount gradually decreases as the line speed increases, whereas on the up path side U, as the line speed increases, the amount gradually increases.

Therefore, in this invention, the flow rates of the plating liquid on the down-pass side and the up-pass side are adjusted to D′ and D′ shown in FIG.
U′ so that there would be no difference in flow rate between the two. For this purpose, an accelerated injection nozzle 10 is installed on the down-pass side D, facing the gap 4 in the opposite direction to the direction in which the strip 7 passes, but facing the liquid flow, and on the up-pass side U. A deceleration injection nozzle 11 is provided in the direction opposite to the direction in which the strip 7 is passed through, and the flow is counter-current to the liquid flow, and the plating process is controlled so that there is no difference in the flow rate of the plating liquid on each side. I decided to do so. By performing such operations, the critical current density can be maintained at a high level,
Can increase line speed.

The reason for suppressing the flow rate on the up-pass side is
If you simply accelerate the liquid flow on the down path side, the pull on the up path side will be strong, which will reduce the effect of acceleration and make it impossible to obtain a sufficient flow rate of plating liquid. Therefore, it is necessary to slightly suppress the liquid flow rate on the up path side. That's what I did.

As mentioned above, in order to keep the plating liquid flow rate constant on both sides, it is necessary to accurately detect the flow rate on the down path D side and up path U side. A sensor 12 is provided to measure the potential difference between the
Use a hot wire flow meter, etc. Then, based on the above-described flow rate detection, the opening degrees of the valves 13 and 14 are adjusted to perform the above-described flow rate control.

As explained above, according to the present invention, the flow rate of the plating liquid on the down-pass side can be increased, so the critical current density can be set higher.
As a result, the line speed can be increased, which improves productivity. In particular, in the case of the present invention, a drop in ion concentration at the cathode surface can be avoided, thereby eliminating the generation of hydrogen, etc., and is therefore highly effective when applied to Mn plating, etc., which generate many bubbles during plating.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a radial cell for electroplating, and FIG. 2 is a characteristic diagram showing the relationship between the flow rate of the plating liquid and the line speed. 1... Plating tank, 2... Rotating drum, 3... Anode, 4... Gap, 5... Main pipe, 6... Plating liquid, 7... Strip, 8, 8'... Deflector roll, 9... Pump, 10... Accelerated injection Nozzle, 1
1...Deceleration injection nozzle, 12...Sensor, 13,1
4...Valve.

Claims (1)

[Claims] 1. A strip that is in contact with the outer periphery of the energizing rotating drum and runs periodically with its rotation is connected to an anode provided with a gap in the radial direction from the strip, and is introduced into the gap from below the anode. In a method of performing plating processing by applying electricity through a plating liquid, adding a plating liquid that accelerates the liquid flow to the gap near the entrance side that becomes a down pass,
Alternatively, a high-speed plating method in radial cell electroplating, characterized in that the plating process is performed by adding a plating liquid that decelerates the liquid flow to the gap near the exit side that becomes the up pass.