Bev,
If the spots like like individual reflowed solder balls from solder paste they probably are. Although solder paste is not stencil printed on the pads with the spots my guess is that small amount of solder paste is being transfered to those pads during stencil printing.  Check the way the company does stencil printing and how they clean their stencils.  If they wipe their stencils after N number of prints they are probably smearing solder paste over the bottom surface of the stencil and that is what is transfering to the pads.
 

Regards,
George
George M. Wenger    (609) 639-3210    [log in to unmask]
Celiant
Route 569 Carter Road                        PO Box 900
Hopewell, NJ 08525                             Princeton, NJ 08542-0900

-----Original Message-----
From: Bev Christian [mailto:[log in to unmask]]
Sent: Friday, September 14, 2001 10:34 AM
To: [log in to unmask]
Subject: [TN] Technical question - immersion gold

Here's the situation:
 
We have immersion gold over nickel boards made by two different board shops, populated by different companies and in both cases we have spots of reflowed solder on the gold contact pads after reflow. 
 
The board shops use no tin/lead in their gold/nickel processes.  The boards did not come in with this problem.  These pads were not screen printed with paste.  Both ovens use edge fingers.  Both ovens are convection.  Some boards were actually run through the oven up-side down and the problem was still observed.  The problem is only seen on the one board type, although we have others that are immersion gold over nickel.
 
Has anyone every seen anything like this?  What do you think caused it?  I have my suspicions, but I will keep them to myself and see what you have to say first.
 
regards,
Bev Christian
Research in Motion