I am a Quality Engineer which went from an Automotive QS9000 company manufacturing ceramic hybrid boards and now I am with a ISO PC mfg. company dealing with PCBA boards. I've been assigned a task in determining the contributing factor to high contamination levels (dendritic growth) found on our boards, 20 - 80 ug/in^2. The test,Ionic Contamination (Electromigration) Test , was performed on 5 PCBA boards by an outside lab using IPC-TM-650 2.6.14 Rev. A standards. My question is, what could be the root cause. Could it be the no-clean flux? If so, what type of flux should be used to reduce the contamination levels? As part of a containment action all boards will be washed. Please help. Thank you.