Hi TechNet-
     
     One possible cause of your problem may be your printed wiring board 
     design but not the pads (your pad dimension look ok to me). If one of 
     the pads is tied to the board inner layers it may heat up slower than 
     the other pad. When the solder paste deposits don't become molten at 
     the same time then the surface tension of the molten deposit will 
     "jack" the other end of the component out of/off of the nonmolten 
     paste deposit. Your component dimensions play a part in this equation 
     but check and see if the components are always tombstoned to a 
     specific pad and check out the pad inner layer connections. Good Luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Tombstoning 0805 Film Caps
Author:  [log in to unmask] at ccmgw1
Date:    12/17/96 1:30 PM


   I would greatly appreciate any help I can get in reference to tombstoning of
plastic film caps.  My
pad design for each terminal is .060" X .050". The .060" dimension is for width 
of the cap.  Each
terminal is centered on the .050", leaving .025" of the pad exposed on each side
of the cap. We
have to run the parts perpendicular to the direction of travel through the 
reflow because it is critical to
the design. Please reply if anyone has experience with this.  Thanks.
     
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