Hi We have seen failures on a bought-in assembly due to growth of copper sulphide on the copper traces of a flexible PCB. The failure occurs at the base of SnPb solder joints, where the copper traces are not covered by photoresist. The whole area of exposed copper and solder joints is covered by a silicone based potting material. Unfortunately our supplier is not being very helpful, so I am looking for clues as to what is happening and how to stop it myself. The source of sulphur is not known, but there are various rubber components within the immediate area. Does anyone have any experience of this type of corrosion system? If so, I would appreciate a discussion about the factors involved - in particular, the role of the potting compound and whether an alternative passivating material would do a better job. Thank you John Loveluck Group Quality Manager Tadpole Technology plc Cambridge Science Park Cambridge CB4 4RB Tel: (+44)1223.428200 Fax: (+44)1223.428201 email: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************