One obstacle to be able to "hold a narrow etch rate window with fewer bath changes" that has not been mentioned as yet is the fact that commercial copper foils do not have fixed etch rates. Just as other properties of Cu foils, like strength, ductility, specific gravity, electrical conductivity can vary even from lot to lot from the same foil manufacturer, so does etch rate. This variability comes from variations in the plating chemistries, which as I understand causes a variation in the amount of bath constituents, such as organics, to be plated out at the grain boundaries. The more such materials are co-deposited at the grain boundaries, the lower the previously mentioned properties except etch rate, which goes up. Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 201-543-2747 E-mail: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************