1. There are some people that use microetch only prior to application of LPI solder mask with good success. Normally you want to microetch about 30-49 microinches to obtian a good surface. The important thing to remember with microetch only is to apply the solder mask after the microetch/rinse/dry as soon as possible (within 15 minutes is recommended and no longer than 1 hour). Microetched copper surfaces oxidize much faster than mechanically scrubbed copper and these oxides can interfere with adhesion. 2. Pumice is actually ground up lava from volcanos. It is a highly abrasive material and does produce an excellent surface for the adhesion of LPI solder masks. Tests have shown that it provides the overall best surface; however, pumice machines are expensive and require a lot of maintenance because of the abrasive nature of the pumice. Hope this helps. Larry Fisher Dexter Electronic Materials [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * 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] * ***************************************************************************