My experience is the "contamination with sulfur" usually comes from how you stored the board, did you interleaf with sulfur free paper, what did you do with the cardboard box, I believe upon investigation you will find part of making paper products(check sulfite paper pulp for info.) gives them inherent sulfur. Manko in Solders and Soldering in the 1964 edition says" A word about sulfur is in order. This contaminant which has a detrimental effect on wetting is reported to be dangerous at levels of 0.03%(in solder)" In addition most sulfite have low solubility and once gotten are hard to get rid of. ---------- From: [log in to unmask] To: [log in to unmask] Subject: Sulphur contamination Date: Thursday, April 25, 1996 10:43AM I am interested in finding out potential causes of contamination of PCB,s with sulphur. What typical fabrication or assembly processes may introduce this contaminant to the board. What are the long term potential effects of sulphur contamination and are there any studies I could reference. Any suggestions or papers would be appreciated.