Hi Bev! Is it possible that the assemblies are picking up "stray" solder
particles from the reflow oven edge fingers or some other associated reflow
oven hardware?

Dave Hillman
Rockwell Collins
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Bev Christian <[log in to unmask]>@IPC.ORG> on 09/14/2001 09:34:13 AM

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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


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