During the process of using bright acid tin plating additives, sometimes the workpiece in the middle of the hanger will appear white and not bright enough. What is the reason for this?
Based on on-site experience and the characteristics of Sn-807, a bright acidic tin plating additive, Bigley Technology has analyzed the following five main points:
1. The main salt content in the plating solution is low. In general, the concentration of stannous sulfate and sulfuric acid in the plating solution should be controlled within the process range to ensure good positioning performance of the plating solution. When the concentration of stannous sulfate or sulfuric acid in the plating solution is low, it will reduce the current density of the cathode, causing some workpieces to appear white and not bright enough.
2. Insufficient concentration or poor movement of brightener. The brightener in the plating solution can improve cathode polarization, making the plating layer fine, uniform, and bright. When the concentration of brightener is insufficient, some or all of the workpiece is not bright. However, some brighteners on the market have poor mobility, and the workpiece is prone to insufficient brightness in low current regions.
3. Improper operating parameters. When the temperature in the plating solution is low or the current density is low, the deposition speed is low, and the coating cannot obtain a completely bright coating. Therefore, operating parameters such as current and temperature should be controlled within the process range during production.
4. Anode plate passivation or insufficient area. The anode plate for acidic tin plating should use 99.9% or more tin anodes. Low purity can easily introduce impurities and also lead to passivation of the anode plate. When the anode plate is passivated, it will seriously reduce the current density of the cathode, resulting in a decrease in the brightness of the workpiece. In addition, the insufficient area of the anode plate can also cause the workpiece to not receive sufficient current and appear white and not bright.
5. There are large impurities in the plating solution. As production proceeds, the content of metal impurities such as copper and iron in the plating solution will gradually increase. In addition, the decomposition products of brighteners and the accumulation of organic impurities such as grease will deepen the color of the plating solution, increase its viscosity, and the workpiece coating is prone to appear gray. Therefore, during the production process, it is necessary to strengthen the maintenance and management of the plating solution and regularly use activated carbon to treat the plating solution.
Therefore, when using bright acid tin plating additives, the workpiece in the middle of the hanger may appear white and not bright enough, attention should be paid to the above five points to resolve the fault as soon as possible and avoid increasing unnecessary production costs. If you are interested in bright acidic tin plating additives, please contact Bigley Customer Service for free samples and detailed technical information!
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