Steve

We have seen this event before at CSL.  This appears to be a soldermask that
was was overcured at the fabricator and then more at wavesolder.  The
soldermask had poor adhesion to the copper ground areas and the temperature
cycle conditions created the loss of the soldermask by lifting and peeling
off.  The rings appear to come from the thermal effects on the copper
material from wave soldering. Look for soldermask flakes at the bottom of the
chamber.

Terry Munson

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