Summary for copper to copper delamination Discussion
Copper to copper delamination was reported on a chrome-plated part after some parts fell off the rack during copper plating, and the rack tension was later corrected. The questioner, Richard Kim, asked whether bipolar effects in an acid copper bath could explain the blistering and requested a clear theory. Russ Richter explained that if a part in a rack goes dead, it can become bipolar: the side facing the anodes may keep plating while the opposite side can deplate, and repeated current interruptions can create multiple layers of plating. Lyle Kirman added that if the process uses an alkaline copper strike followed by acid copper, poor rinsing between the two steps may be the real issue, because surfactants from alkaline baths are not compatible with acid copper baths. The thread suggests checking rack contact, current interruptions, and rinse quality between copper steps.
June 10, 2013
Q. We had copper to copper delamination problem on chrome plated part.
There was no down time (power outage) but copper to copper blister problem has occured.
Rack tension was poor so some parts were falling off during the copper plating.
The racks were replaced with new ones.
As I know, Bipolar effect can cause copper to copper delamination problems in Acid copper bath.
Is there anyone who can clearly explain this Bipolar phenomenon and theory?
Thank you
Richard Kim
– Michigan, USA
A. If you are plating a rack of parts and one or more go dead for any reason the dead ones will go Bi-Polar. That is since they are within the fields the side of the part closest to the anodes will continue to be negatively charged but a lamination MAY or MAY-NOT occur on that side of the part. The opposite side of the part will become positively charged and actually deplate. If the current goes on and off many times during the cycle there will be many layers of plating.
Russ Richter
– Danbury, Connecticut, USA
A. It is not clear what your process is, but since you are apparently plating two layers of copper I am guessing that you have an alkaline copper strike, followed by an acid copper bath. If this is the case, then you may need more thorough rinsing between the two copper plating steps. In general, the surfactants used in the alkaline baths are no compatible with acid copper baths.
Lyle Kirman
consultant – Cleveland Heights, Ohio
June 20, 2013