Good evening Techies We have a customer who has discovered a "black deposit" underneath an electrolytic capacitor that has caused a circuit failure. They conformally coat the assembly using a classic AR coating and claim that the coating softens the seal on the capacitor. We are awaiting the results of a surface analysis they are running to determine what the "black deposit" might be. We believe that the solvents in the coating might be attacking the capacitor seal causing the leakage, but cannot understand why this should happen on components from a reputable supplier. The customer has changed the component supplier, but the problem seems even more severe. The end product is safety critical Class 3 - folks may die if the product fails. Can you good folks maybe shed some light on what might be done to overcome the problem? Change the seal on the capacitor and if so, what type of seal should be used? Anyone with similar experience? -- Regards Graham Naisbitt [log in to unmask] Cell: 079 6858 2121 Office: +44 (0)1252 813706 Concoat Limited - Engineering Reliability in Electronics Web: www.concoat.co.uk and www.concoatsystems.com --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------