I have a customer who is designing in an IBM PowerPC 440GP embedded
processor in a 552 ball CBGA package.  Due to routing constraints, he
needs to increase the space between pads of some outer perimeter pads.
IBM's recommended pad size is 27.5 mil, 40 mil pitch..  As this is a
CBGA, IBM has done extensive reliability studies to come to this pad
size.  My customer is thinking of changing some of the pads to an oval
shape to increase the gap size but also to retain the same solder volume
in the hopes that this will be an equivalent pad in terms of long term
reliability.

 

Has anyone tried this with success?  Any other suggestions?

 

Thanks

Peter

 

 

 


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