At the end of the PTH line, after the acid dip and rinse, put in an 
anti-tarnish and DI rinse.  Then the boards must be DRIED completely before 
any stacking or before df lamination.  Most electroless copper suppliers 
also supply an anti-tarnish for this purpose.  An alternative would be a 
separate, small conveyorized line consisting of 5% sulfuric 
acid/rinse/anti-tarnish/rinse/ dryer, that would feed right into the df 
lamination area.  I believe the anti-tarnishes are mostly benzotriazole 
types.

Patty
 ----------
From: Eltek Ltd. - Process Engineering
To: technet
Subject: Thick Electroless
Date: Tuesday, November 26, 1996 8:10AM


Hello Technet !
We intend to switch our PTH process from thin copper electroless plus
electrolytic strike to thick ( hot ) electroless , 2 microns thick . The
line will be loaded with baskets , so we do expect the PCBs will be
oxidized.We are considering some kind of chemical treatment prior to dry
film lamination instead of pumice scrub.Wjhat kind of treatment is
recommended ?

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