Ed,
Look at your cleaning process, it looks like you have flux residue. Are you
cleaning with alcohol after reflow? If you are you will get a white residue
between the pad and the soldermask part of the PWA. Talk to your solder paste
manufacture and see what they recommend for a cleanning process.   

Hector Valladares
Honeywell Space Systems Florida
813-539-3683
Email [log in to unmask]
_______________________________________________________________________________
From: Knowles, Ed on Tue, Oct 15, 1996 2:09 PM
Subject: SMT Solder Joint Film
To: Return requested) (Receipt notification requested


We are noticing a film on our SMT solder joints.  It doesn't seem to 
affect ionic cleanliness or conformal coating adherence, but can only 
be removed mechanically with a brush or Q-tip.  It has a slightly 
yellowish color in most cases and appears powdery.  Is this 
contamination from the PWB pads or part leads floating to the top, or 
a compound derived from the solder paste (63/37 RMA)?  Any insight 
into what this contamination is would be appreciated.
Thanks.

Ed Knowles
Lockheed Martin Astronautics

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