I have a customer who gets a gold tarnish on copper traces after cupric
etch. It is usually worst with higher weight copper, and looks to be
related to rinsing. The tarnish is not removed in the strip/rinse /dry
process after etch. When the tarnish becomes extreme it effects the
coverage of the Cobra-bond. The alkaline cleaner prior to the Cobra-bond
does not remove the tarnish. I'm trying the maximize the rinsing as much
as possible. I'm also thinking about upping the normality of the cupric
(currently .3). They also etch a lot of boards that been put thru
Cobra-bond to help with the adhesion of the dryfilm. This is a new
process. Would this cause a problem with the cupric? Any thoughts.
Thanks in advance.

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