Roger, What you undoubtedly are seeing, is the distinctive color of cobolt used as a hardener in conjunction with the nickel. Many years ago in the time of tin/lead IR reflow and poor materials this cobolt stain would raise it's ugly head. At another large OEM we had this condition tested and verified that 1; it was cobolt and 2; that it created no functional problems other than cosmetics. The root cause never was fully understood. It seems to to have been a combination of over scrubbing the laminate, low resin material i.e.; it was particularly prone to attack cheap double-sided work, and poor rinsing after gold. The # one cause seemed to be low gold bath efficiency, and/or high brightener/hardener levels. To complicate matters you knew for sure if it was'nt there until after reflow. Perhaps the high temp in combination with the chlorides in the fusing fluid reduces the cobolt from an invisible valence state down to it's common purple one. I have been able to make the purple go away in a HOT (175) STRONG CAUSTIC SOLUTION. But even this was probably just oxidizing it back to some invisible state and ruining the material. Perhaps one of these real chemists can tell us what the actual states are. Welcome Mr. Hamilton and your Quazillion years of valuable experience. Robert E. Welch Process Specialist Email: [log in to unmask] Modem: 804-239-9120 Fax: 804-237-3048 ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################