With as high a density part as you describe your solder joints will 
     also be very small.  A through hole via in pad will suck up a 
     significant amount of solder that could be very difficult to 
     compensate for.  You may be at the level to consider laser vias.  
     Laser blind vias can be placed in the center of smd pads without a 
     significant effect on solder volume reduction or solder joint 
     integrity.  There are several PCB manufacturers that would gladly 
     assist you in this direction.
     
     Guy Willingham
     Zycon/Hadco Corp
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Via in Pad
Author:  [log in to unmask] at corp
Date:    4/10/97 8:30 AM


All,
I am designing a board that is about 100% package density. It is a 
combination Digital and Analog design. It will be reflow top side only. 
Most of the parts are small and do not have room under them for via's. Has 
anybody used the Via in Pad technology? What has been you experience with 
it? I realize that the Vias will tend to thieve the solder during reflow, 
and cause problems.
Regards,
Fred Pescitelli
Phoenix Designs
1285 Turner Rd.
Lilburn, GA 30247
V-770-923-3465
F-770-923-2272
[log in to unmask]
     
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