I believe the advantage Persulfate has over peroxide sulfuric in removing residues is it's undercutting ability due to the nature of the etch. At a previous job, I had used the Persulfate to do what you suggest. I also have learned that it is better to spend the resources trying to fix the residue problem than band-aid the problem with a more aggressive etch. What I found was that unless you want to etch huge amounts of Copper to undercut the mask residue, the fix will work when the residues are mild, but fail when they get bad. ______________________________ Reply Separator _________________________________ Subject: HASL Microetch Author: [log in to unmask] at corp Date: 9/26/96 11:12 Does anyone have information, opinions or preferably data regarding micro etching with persulfate vs sulfuric acid/peroxide chemistries? We are currently using a sulfuric acid/peroxide based microetch at the HAL line, and are considering alternatives. I have seen some information which suggests a persulfate based chemistry is better at removing solder mask residues. Any feedback would be appreciated. Jim Kenny *************************************************************************** * 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. * ***************************************************************************