Hi;
 
 We use a mechanical scrub (Aluminum Oxide) in a pumice scrubber prior to 
 resist application.  Variables are minimized by normal process controls 
 (i.e. concentration of Aluminum Oxide, brush pressure, conveyor speed etc.). 
 What might help before Ni/Au plating, is to chemically clean and 
 electrolytically copper strike (pattern plate) approx .0001" prior to Ni/Au 
 plating. This will provide an optimal surface for the Nickel.  You might 
 also want to look at your cleaner and microetch in the Ni/Au preclean 
 process.  Finally, you should contact your photoresist vendor and see if the 
 resist you are using is optimal for the process you are trying to perform.
 
 Good Luck!
 
 Greg Schroeder
 
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______________________________ Reply Separator _________________________________
Subject: FAB: Manual Scrubbing prior to NiAu
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    6/6/96 10:27 PM


Address,
 
EXPLANATION:
 
I have been conducting some experiments on the use of mechanical 
and chemical scrubbing on panels prior to resist lamination.  We 
currently perform a mechanical scrub to all panels prior to resist 
lamination.  
 
Based on minimal testing, we are successful in chemical cleaning 
panels prior to resist lamination with no resist breakdown in 
deep electrolytic Ni and Au.  However, in the test process 
we conducted a tape test and discovered NiAu peel from the base 
copper (no electrolytic copper applied due to reason of test).
 
The NiAu peel from the copper occurs on mechanical scrubbed 
and chemical clean sample panels, but on different sides.  The
mechanical scrubbed panel has peel on the component side and the 
chemical clean panel has peel on the solder side.
 
So the problem now points to the method in which we prepare 
panels prior to Ni and Au plating.  To insure good adhesion 
between Ni-copper and Au-Ni, panels are manually scrubbed with an 
abrasive pad.  Recent observation shows there is a large
variable associated with this type of method.
 
QUESTION:
 
-I would like to discuss with other manufacturers who use deep 
 Ni and Au plating?
 
-What types of methods are others using to prep panels prior 
 to Ni and Au plating?
 
-Is the method chemical or mechanical and if mechanical how are
 variables minimized?
 
Please advise.  Thank you.