A little more information is needed to reply to this message.  When you send 
out the board is it still in panel form?  If not, some hot air leveling 
machines clamp on to the board and if the pads are under the clamp they can 
get stuck and ripped off especially if the solder solidifies before the clap 
is removed.
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From: [log in to unmask]
To: [log in to unmask]
Subject: Lifted pads from HAL
Date: Friday, June 28, 1996 1:16PM

Dear Technetters

   We send some of our boards out of plant to be hot air leveled.  When we 
receive the boards back we have noticed a very small number of the boards 
have isolated surface mount pads that are missing.  There is no visible 
damage to the surface of the board surrounding the area where the pad 
was.The surface of the board under the surface mount pad looks rough like 
the pad was pulled off the base laminate.  There is evidence that mechanical 
force was exerted sufficient to break fibers and remove some of the glass 
epoxy with the pad.  We are only seeing 1 or 2 pads on a panel which seem to 
be in the same general area, however we don't have enough observations to 
draw any conclusions.  Has anyone seen this condition?  What could the 
possible cause be?