I am having some problems with some PCB's that were manufactured approx. 1 year ago.  
According to the manufacturer of the printed circuit boards, ionic readings prior to 
shipping read from 1.2 to 3.0 micrograms per square inch.  The boards were having a 
problem going through the assembly line, so we decided to do additional ionic testing to 
see if it was a contamination issue.  The readings nearly quadrapled from the original 
readings reported by the manufacturer.  We had also noticed a high level of sodium and 
chlorine when conducting our testing.  My questions are:

1.  What would cause the ionic readings to intensify over time?
2.  What could be the possible origins of sodium and chlorine?  Could they be introduced 
in any of PCB manufacturing processes?

Any comments are greatly appreciated.

Scott

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