IONIC CLEANLINESS TESTING RESEARCH OF PRINTED WIRING BOARDS FOR PURPOSES OF PROCESS CONTROL
Authors: Mike Bixenman, D.B.A., Ning-Chen Lee, Ph.D., and Steve Stach Company: Kyzen Corporation, Indium Corporation, and Austin American Technology Date Published: 10/4/2009
Abstract: Ionic Cleanliness testing machines are designed to determine the total ionic content extractable from the printed wiring board for purposes of process control. The conductivity of the extract solution is measured and the results are expressed as sodium chloride equivalence per unit area. The problem with this method is two fold: 1.) Many of today’s low residue flux and lead-free flux residues are not soluble in the extract solution. 2.) Contamination of concern is with site specific components, from which contamination does not correlate to the area of concern. The purpose of this study is to research low residue and lead-free flux structures, identify solvent compositions that will dissolve these residue types, and offer options for performing both bulk and site specific ionic cleanliness testing methods.