Hi all

I have a case here where I am not sure what I see. 
- There are dark spots visible below the solder mask on the surface of the traces on a PCB. I attached 2 Pictures in JPEG that show a view onto the surface of the traces with 10x and 40x magnification.
- In microsections we see clearly a cavity between the traces and the soldermask. 
- EDX is hopeless, since the dark layer is so thin that the background covers all but the copper peak.

Before I start to work with TOF SIMS, Spectroscopy and other expensive analysis methods I'd like to ask whether one of you knows what the dark spots are.

Thanks in advance. Have a great day.

Guenter

Guenter Grossmann
Swiss Federal Institute for Materials Testing and Research EMPA
Centre for Reliability
8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :      xx41 1823 4054
mail:     [log in to unmask]

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