Hey all, I have just had a few questions raised regarding a customers product and it's reliability. Presently, they are potting a control circuitry into a siliconne rubber mould. This is sealed and then installed in oven control systems. What appears to be happening is, over it's lifetime, for some unknown reason, the ends of the SMT caps is corroding and giving intermittant faults. If you pearce the siliconne rubber mould and press on the end cap with a probe, it then forms a contact and the fault goes away. The PCB itself is an FR4 PCB with HASL finish, and has an operating current of around 6mA. The product is washed once inside the oven control, but shouldn't the siliconne rubber protect this sufficently enough??? Since the rubber is a permeable compound, is it possible for water to make it's way into the mould and onto the surface of the PCB and then not escape???? Would this lead to the corrosion of the end caps??? Cheers Mike --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------