Good overview of the process.  From the ionic contamination standpoint, it is
important how you measure ionic contamination.  Some elements, such as weak
organic acids in no-clean fluxes will show up in an Omegameter-type of
instrument as an ionic contaminant, but are benign on a circuit board.  We
work with customers who have dendritic growth, corrosion, or electrical
leakage on their assemblies.  In almost every instance, we have correlated
high levels of chloride or bromide to the electrochemical migration.  Ion
chromatography (IPC-TM-650, method 2.3.28) is the best measurement of ionic
residues.

Doug Pauls
Contamination Studies Laboratories
[log in to unmask]