We have observed corrosion caused by ionic impurities in adhesives we are
using for an application.  We have looked at total content (burn off) and
extractable ionics (90 deg C, 40 hrs). 
1)What standards/ procedures are accepted for measuring Ionic impurities :
On or in flex circuits?
on/in PCBs?
in adhesives for PCBs?
In adhesives for chip attach?

2)What are acceptable levels of contamination in each of these applications?  

3)We have been told that 200 ppm is acceptable for PCB applications while IC
people require 20ppm.  Is this true?

4) What are the primary ions that cause trouble.  Cl, Br, F others?

Josh Smith
Information, Imaging and Electronics Sector Research Laboratory
3M co
612-736-1101