The Effect of Electroplating Etching Retention Time on the Discoloration of Electroplated Nickel Gold Plate for Electric Heating Tubes

The Effect of Electroplating Etching Retention Time on the Discoloration of Electroplated Nickel Gold Plate for Electric Heating Tubes

To verify the effect of etching retention time on the discoloration of electroplated nickel gold plates, targeted experiments were conducted in two rounds, using the same model and specification. The etching was completed at different times, and the amount of discoloration on the gold surface was checked. The data results of the two rounds of experiments are shown in Tables 6 and 7.

The experiment shows that if the etching is not done in time and the retention time is too long after gold plating, it can also cause discoloration of the gold surface. After gold plating, it is generally necessary to achieve etching within 30 minutes. If left for too long, it is easy to cause impurities on the gold surface and discoloration. Especially for boards with slightly larger solder pads, it is necessary to strengthen the control of the etching time after gold plating, and immediately etch after gold plating.

3.5 Water quality requirements

(1) After copper plating, the gold-plated plate should be washed with DI water quality, and the conductivity should be preferably controlled at 60 μ Below s.

(2) After etching and before air drying, DI water must also be used for washing. The etched pickling tank should be replaced and pickled once per shift, as the copper ions in the pickling tank affect the discoloration of the gold surface.

(3) During the production process, excessive impurities will accumulate on the absorbent sponge before etching and drying, which will contaminate the board surface. During production, it is necessary to regularly clean it with DI water and replace the absorbent sponge every 1-2 months.

Timely etching after gold plating and improving water quality can reduce the probability of foreign matter ion pollution on the board surface, and is effective in improving color change.

4. Summary

Analysis of possible causes of discoloration on the gold surface: (1) Excessive porosity in the nickel layer caused by copper ion migration; (2) Nickel surface passivation; (3) The foreign objects attached to the gold surface have undergone ion contamination.

Measures were taken from the following five aspects, ultimately achieving good results and improving the quality defect of discoloration.

(1) Control measures for nickel plating cylinder: The current density of nickel plating should be appropriate, and the impurity removal treatment of electrolytic nickel cylinder should have a low current density. At the same time, after nickel plating, the gold plating process should be completed within 0.5h-1h.

(2) Gold-plated cylinder control measures: 1 is recommended for filtration μ Monitor the uniformity of gold plating for filter cartridges of size m; Use a dedicated gold-plated fixture.

(3) Control measures for the curing tank: The water conductivity should be within 10 μ s. Change the water for each shift, and at the same time, maintain the water temperature in the curing tank at 18 ℃~25 ℃.

(4) Etching time control: It is recommended to complete the etching within half an hour after gold plating.

(5) The water quality requirements are: the water in the curing tank should be frequently changed, with low conductivity, and special process sections also require the use of DI water quality.

www.superbheater.com