Techies - I am being challenged to confirm or dispute a  suggested correlation of  vulcanized rubber ESD matts with some tarnishing  and  ("potential") creep corrosion we are seeing.    Have tested the ESD matts with a classical sulfur "wet" spot test (Feigl) and have confirmed sulfide its presence in most matts which is not un expected. 

Issues we are having is sporadic and not at all consistent to all ImAg  PCBs so I am sure (and aware)  there  are  numerous other factors associated with this tarnishing/corrosion we are seeing.  

Does anyone have any  experiences they can share,  good studies or aware of any papers that may be of use in my quest?

Is anyone of additional risk  associated with any  specific PCB ImAg plating process? 

Thanks in advance.

Rich  Kraszewski 
Senior Staff Process Engineer

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