Improve the pass rate of plating

In the pyrophosphate copper plating process, if there are fine pits or pinholes in the coating, there is no doubt that it will cause a decrease in the qualification rate of the coating and also have an impact on the subsequent plating process. So what are the causes of the malfunction? How to make a judgment?
Several common triggers for the appearance of fine spots (or pinholes)
Generally speaking, in the pyrophosphate copper plating process, there are several factors that can cause the appearance of fine pits or pinholes in the coating:
① Poor matrix metal structure
② Excessive oil or organic impurities in the plating solution
③ There is oil in the cleaning water or activation solution before plating
④ The pH value of the plating solution is too high
⑤ Plating solution turbidity
wait.
What methods do we need to use to determine the cause of plating failure?
We can conduct an experiment by first polishing, brushing, degreasing, and activating copper parts, and then directly plating copper with pyrophosphate to determine whether the fault is caused before plating or in the copper plating solution.
If copper parts are directly plated with copper and there are no pitting or pinholes, it indicates that there may be three possible causes of failure:
① There is oil in the cleaning water before plating
② Poor matrix metal structure
③ Caused by oil in the activation solution
I would like to add that this type of pitting (or pinhole) fault often occurs on the downward side of the part, so we can also make a judgment by observing the phenomenon and checking the surface condition of the base metal.
When using copper sheets for direct copper plating, if there are still pits (or pinholes) on the coating, the cause of the fault is mostly in the copper plating solution. The abnormal situation of copper plating solution can generally be divided into the following three types:
① Excessive organic impurities (or oil) in the plating solution
② The pH value of the plating solution is too high
③ Plating solution turbidity
And the faults caused by these three possibilities are also different in the places where they appear on the coating. At this point, we need to make judgments and analyses based on the different phenomena of the fault:
a. Pits (or pinholes) caused by excessive organic impurities (or oil) in the plating solution can appear on the lower side of the part or on the upper part of the hanging fixture in cases where there are many
b. Pitting (or pinholes) caused by a high pH value of the plating solution often occur at the edges and tips of the parts
c. Pitting (or pinholes) caused by turbid plating solution generally appear more frequently on the upward side of the part
Based on the different phenomena of the fault, we can conduct necessary small experiments to identify the cause of the fault and carry out targeted treatment.