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Silver plating is peeling from copper base substrate
Q. Hi, I'd like to ask what are the factors that contribute to adhesion failure, or in specific, my silver plating peeled off from the copper base after bake test (350° C, 2 min)? This is very unusual and rarely happens. The plating I use is pulse (DC 50%), and before the silver plating the copper alloy will undergo the following pretreatments: degreaser and electroclean (both at elevated temp), acid pickling, copper strike plate and anti-immersion soak treatment. Can anyone help?
Alani [last name deleted for privacy by Editor]- Malaysia
2000
A. Most likely cause of this is silver immersion plating onto the copper base metal. If you are doing silver spot plating, try adjusting the timing so that the rectifier comes on only a short time after the pump velocity is increased. 0.1 to 0.3 g/l of free CN in the silver also helps.
Another potential problem but less likely is that the anti immersion bath is out of balance.
Good luck.
Pat Mentone
St Paul, Minnesota
2000
Q. Thanks for the information Pat, What about bath contamination? Is it also one of the potential causes? I have done EDX analysis on the underneath layer of the peeled silver and found a noticeable percentage of Si. Whereas, the control sample shows no trace of the element. Thanks.
Alani [returning]- Malaysia
2000
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