Matt - From your description of the dark vs. light areas of copper, I suspect you are correct about a delaminated or debonded condition. The acrylic adhesive used in your flex has a glass transition (Tg) temperature of about 45C, as opposed to a Tg of 240-250C for the polyimide materials in the structure. This means your process temperatures can temporarily turn the acrylic adhesive to something rather like grease. In this state, it is subject to debonding/delaminating rather easily from any form of stress. I would suggest the following as a quick check to confirm: Place the specimen under low magnification (10-20X) and gently squeeze the suspect area with tweezers or similar. If debonded/delaminated you should be able to observe movement in the structure between the cover film and the circuit. Several years ago, DuPont, Sheldahl and others standardized and commenced marketing "all polyimide", "adhesiveless flex" or "bondable polyimide", or whatever you want to call it. This material has a Tg in the 230C or above range, which is much more durable. We have switched over most of our designs and have seen improved product yields at the fab houses and in our own assembly operations, as well. In our case, this has pretty well turned out to be a true "drop in replacement". All of our government sector customers, to date, have agreed that it is a class 2 change.. Good luck - I'm at 256.882.4536 if you need to talk. Regards - Kelly ################################################################ 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 ################################################################