We have run a "no clean, low solids" operation for almost ten years now without any contamination issues. Recently a shorting failure has occurred across a capacitor on a few field returned circuit boards. The failure analysis report came back as electromigration of both tin and lead based on 1) a SEM photo showing the feathery migration tracks similar to silver migration and 2) a spectrum plot showing Sn and Pb peaks. Questions for Technet: Does lead actually electromigrate along with the tin as an alloy? I thought the metals separate during electromigration and the tin would be the culprit. This occurs on a potted board but only in one location which happens to be a high frequency switching application. Why wouldn't it happen all over the board uniformly? Is 2 volts enough to cause the electromigration to occur? Our solderpaste has antimony (0.4%) and silver (0.6%) in it as well as 63% tin ( and the rest is lead). Shouldn't the spectrum be showing these components as well or is anything under 1% not discernible? Is it possible for the bare board to be the culprit as it is a HASL board? Any insight would be appreciated. Phil Bavaro ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################