Hi Victor -
     
     BGAs on both sides is doable - but it is not very much fun. I have 
     seen some SMT test boards with double sided BGA but there was careful 
     selection of BGA pad size and weight so that the solder surface 
     tension was favorable and the reflow profile was very rigidly 
     controlled with little room for error/changes. The process window was 
     considered to be too tight and the design never went to production. 
     There may be other TechNetee's that have made the last leap. Good 
     luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Re: BGA assembly.
Author:  [log in to unmask] at ccmgw1
Date:    12/10/96 10:08 AM


     
Hi Victor,
     
I have seen one side QFP and the other side BGA. Both sides mount with BGAs, 
I have not seen before.
     
To do that, reflow the side with QFP first, of course please remember to 
glue the
QFP, then reflow the other side with BGA.
     
That's all...This is what I have seen.
     
In case you ever seen reflow BGA both sides of the Board, please do tell 
me. I am
curious to know too..
     
     
     
     
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