As a HASL service provider we see the entire gambit of solder mask 
     residues.  We use a persulfate based etchant at a rate of 40-60 
     microinches.  The trade off is that it is much more difficult to rinse 
     than peroxide/sulfuric chemistries and can cause non-wets if not 
     entirely removed before entering the HAL machine.
     
     
     Michael Holan
     Process Engineer
     Radian Electronics Div.
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: HASL Microetch
Author:  [log in to unmask] at INTERNET
Date:    9/26/96 12:57 PM


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
     
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