In our production process using tin plating brighteners, sometimes the solderability of the coating is poor. Do we have any good measures to solve this?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product's tin plating brightener Sn-807, The premise of good solderability of the tin-plated layer of the workpiece is that the plating solution is clean and stable.During production, to prevent the occurrence of Sn2+ oxidation and Sn4+ hydrolysis in the plating solution, and to deal with the turbidity of the plating solution in time, to improve the solderability of the tin plating layer, the following measures can be taken:
1. Regularly analyze the plating solution, and adjust the main salt concentration in time through the analysis results.
2. Regularly use a large-area cathode plate before production or during shutdown, and electrolyze the plating solution with a small current to remove metal impurity ions in the plating solution.
3. Regularly treat the plating solution with activated carbon and filter it, but it will absorb part of the brightener, so the tin plating brightener should be properly supplemented after treatment.
4. Excellent stabilizer should be used in the plating solution, which can effectively prevent the natural oxidation of Sn2+ in the plating solution.
5. High-purity tin plate (above 99.5%) should be used as anode to prevent anode passivation, and the surface of anode plate should be brushed regularly, and a protective bag should be put on if necessary.
6. The non-oxidized and yellowish stannous sulfate should be used as the main salt of the plating solution when matching the tank, which can avoid the turbidity of the plating solution.
7. In the process of tin plating, the temperature and current density of the plating should be strictly controlled to avoid the oxidation of Sn2+ in the plating solution to Sn4+.
8. Impulse current should be used when the workpiece is put into the tank, especially for workpieces with complex shapes, to prevent strong acid corrosion from contaminating the plating solution.Impulse current should not be too high, generally controlled at 0.5~2.0A/dm2, to prevent oxidation of the plating solution.
9. Always check the workpiece hanger to prevent cross-contamination caused by residual liquid from damaged insulation.
Therefore, we need to pay attention to the above points in the production process of using tin plating brightener, which can effectively improve the solderability of the tin plating layer and reduce the occurrence of failures.