John, Pertaining to the apparent contradictions contained in items #1 & #2, as can often happen in this business they are both correct. Acid will indeed help finish crosslinking the polymers if they have not completely "kicked over". However a acid cleaner with a strong oxidizer, such as free flouride or chloride ions, will also help undercut and actually remove thin residues prior to surface finishing. Because of this we have a chamber of solder stripper prior to our conventional HASL micro-etch. We run it only rarely when someone or some process up the line goes astray. Such developer problems, excessive hold times, over tack curing, ambient U.V. light ETC. Robert E. Welch Process Specialist Email: [log in to unmask] Modem: 804-239-9120 Fax: 804-237-3048 *************************************************************************** * 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] * ***************************************************************************