We had Au/Ni solderability problems from batch-to-batch from our supplier which was traced to a maintenance problem by our PCB supplier. Surface analysis of the pcbs showed a very small layer of copper is being deposited on top of the gold during the acid clean process. They followed the routine maintenance program supplied by the chemistry vendor but this did not include a copper content check. It appears that as little as 100ppm Cu in the acid cleaner can leave an atomic level layer of copper on the gold that is sufficient to prevent solder reflow. If the solder does flow then the joint will be good and there is no risk of joint degredation. ############################################################## 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. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################