Try doing a copper purge. We purge copper from our solder wave by cooling the pot to just above freezing for 12 (or more) hours. The copper forms 1-3 balls that we scoop out. This generally reduces copper concentration from .2% to less than measurable. This can be done on a weekend. I don't see why you can't do something similar. Aric Parr United Technologies Electronic Controls ______________________________ Reply Separator _________________________________ Subject: FAB: HASL drossing Author: [log in to unmask] at internet Date: 8/5/96 2:42 PM Hello Technet, We are having difficulty maintaining our HASL pot below 0.25% Cu, even with 2x daily drossing. The machine is an old vertical Electrovert with less than easy access. - Is this 0.25% more critical at assembly than at fab? - What is the practical USL for copper in HASL? - How often should metal contaminants be measured? - Should drossing be done at a constant frequency, or based on panel loading? - Are there any studies out there correlating HASL quality with Cu contamination level? - Any special recommended procedures or tools? As always, we appreciate any input. Joe Felts PC World, Toronto *************************************************************************** * 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. * *************************************************************************** *************************************************************************** * 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. * ***************************************************************************