Good day,

We currently are having some considerable difficulty initiating 
plating on some copper surface features.  This copper surface
has seen a coppper sulfate nickel etching step prior to plating.

Our plating line is composed of electroless plating solutions 
(Ni-P, immersion gold and electroless gold).  The Nickel plating
on the copper surface is activated via a Pd seeding bath. 

We have tried more that a few process changes to enable plating;
increased time in the cleaner, the soft etch, the seeder and some
surface pretreatment. A sulfuric acid dip and an additionnal light
pummice srub have been done.  Unfortunetly, none of the above
process (even our rework loop) has yielded acceptable results.
The missing nickel seen here does not seem related to a feature to 
feature galvanic effect has we sometimes see.  Also, it is not an
oxydation problem, the cleaner removes that effectively.

My questions to the TECHNET community are the following:

-Any of you have seen alteration of copper surfaces in the copper
 sulfate etching solution (a MEB analysis shown only a small amount
 of nickel on this surface).

-Any comments from platers or board manufacturers who have 
 experienced the same or similar problems.

-Are there steps in the board manufacturing process known to affect
 the copper surface (and cause plating problems). 

-Suggestions for cleaning effectively the surface

Thank you.


DENIS DIONNE              phone:(514)534-6724  fax:(514)534-7300
IBM Bromont Ltd
Card Plating Engineering
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