Hi John -
     
     I assume that PLCC is a plastic leadless chip carrier. The reliability 
     of LCC's as a component type doesn't rank up in the top ten! The 
     electronics industry as a whole went through quite a bit of testing 
     for several years with the end result that relying on solder for both 
     the electrical and mechanical connection was not a good idea. Your 44 
     pin is a fairly large size and you are putting it on a curve - do a 
     bunch of testing to assure yourself that the joint reliability meets 
     your use environment. Werner Engelmeir is a good source for additional 
     info on the pro's and con's of LCCs - he should be commenting on your 
     question too. Good Luck.
     
     
     Dave Hillman
     Rockwell Collins
     [log in to unmask]
      


______________________________ Reply Separator _________________________________
Subject: smt / pcb or flex assembly ?
Author:  [log in to unmask] at ccmgw1
Date:    12/19/96 1:02 PM


Currently, our design group is considering using SMT parts for 
assembly onto an FR4 pcb [one or both sides] with dimensions:
approx 22" x 3". We are confronted with the question as to whether we 
can do this reliably since this flat substrate/SMT parts mounted will be 
formed [bent] into an arch with a radius of curvature of 36" in the final 
assembled 
product.  
     
The concern is stress on solder joints even though it is a relatively 
small arch.  At this point, we only anticipate using 44 pin plcc [50 mil] and 
discrete smt r's and c's. If particular packages should or should not be used we
     
would like to know . 
     
Can anyone recommend an alternative or a source of information regarding the 
feasibility of doing this. It would be appreciated. Thanks   
     
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