Common stirring and filtering equipment for electroplating

In the electroplating process, many electroplating tanks and auxiliary tanks will adopt stirring devices, which can speed up the deposition speed, produce good coatings, and sometimes also play the role of heat dissipation. The most commonly used stirring methods in electroplating process include compressed air stirring, electroplating solution circulating stirring, mechanical stirring, convection stirring, ultrasonic stirring, etc.

1. Compressed air mixing

Compressed air can fully stir the electroplating solution, which is the most commonly used stirring method. The filtered oil-free and impurity free low-pressure compressed air is introduced into the mixing pipe in the plating tank to make the bubbles rise from below the workpiece and stir the plating solution. The compressed air from the compressed air station can only be used after being purified by oil-water separator and filter. The compressed air from the multi-stage centrifugal compressor may not be filtered. Air stirring has a great effect on the turnover of the electroplating solution, so as to avoid the movement of some kinds of anode sludge to the cathode and attached to the cathode surface, resulting in burrs on the coating surface.

2. Electroplating solution circulating mixing device

The circulating mixing device of electroplating solution is composed of circulating pump, glass tube electric heater, cooling water jacket, etc., as shown in Figure 2-1. Heat exchanger is used for heating or cooling outside the tank to make the electroplating solution flow, so as to circulate the electroplating solution near the workpiece and achieve the purpose of stirring. Usually, the plating solution enters from the bottom of the plating tank and overflows to the storage tank through the overflow port. The heating and filtering device is located between the main tank and the pump.

Electroplating solution circulation stirring not only stirs, but also filters the electroplating solution in the process of repeated flow, but the stirring intensity is weak and the effect is not significant.

3. Mechanical mixing device

(1) Cathode movement stirring cathode movement generally refers to the movement of the cathode rod in the horizontal direction driven by the reduction motor and cam. Although the stirring intensity is not high, it is easy to obtain a relatively uniform electroplating solution. The cathode moving device is composed of a motor, a reducer, an eccentric disc, a connecting rod and a supporting roller. When the cathode moves and stirs, there may be a stirring dead zone in which the electroplating solution follows the movement of the workpiece without disturbance. When the cathode moves, the electroplating solution on the surface of the workpiece flows only slowly. If the cathode is allowed to vibrate with an amplitude of 1 ~ 100mm and a frequency of 10 ~ 1000Hz when moving, the turbulent flow of electroplating solution can be obtained, the stirring effect will be greatly improved, and the upper limit of current density will increase, which can meet the requirements of high-speed electroplating.