There have been many helpful comments on this already, so at the risk of being redundant here are just a couple more: Probably the most commonly used micro-etch for copper is ammonia / peroxide which is easy to get, simple to make up (but it must be freshly made each time) and is fairly harmless to work with. Metallography on thin copper is a bit of an art. Labs that do it all the time know the pitfalls, but heed Werner's warning against using just any lab. The apparent grain structure can be changed significantly by the act of preparing the sample itself. While classic copper annealing is done at relatively high temperatures (600F), it's possible to anneal wrought copper foil at temperatures as low as 325F in a couple of hours. (The difference being made up by the residual energy stored in the grains during the rolling process.) This depression of the annealing time & temperature is typically designed in by the foil manufacturer to suit the needs of the printed circuit industry and matches well with common lamination cycles. In most cases recrystallization only occurs at temperatures above 700F. Andy Magee Flex Guru - Consulting [log in to unmask] (937) 435-3629 ps. Yes, among other things I have an MS in Metallurgy. ################################################################ 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 ################################################################