The one time I had this come up while I was at Rogers the concern was coming out of Europe, and was related to high altitude Corona discharge resistance. They were incorrectly extrapolating problems with polyimide coated wires to flex materials. Fortunately we were able to get test data on the Kapton used in flex from DuPont that allayed their fears. There's also a series of UL flex circuit electrical tests and a qualification level called the delta mark that might also be used to argue against these somewhat unjustified concerns. Andy Magee Flex Guru - Consulting [log in to unmask] (937) 435-3629 ################################################################ 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 ################################################################