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Grid Array package behavior after reflow

Post Date:
07/16/07 
Question:
How does a ball or column grid array package behave after PCB
mounting?
Answer:
This will depend on the material used for the balls or columns:
  • in case of Sn63Pb37 balls (TBGA 240, CBGA 68, CBGA 152,
    CBGA 255 packages for example), the eutectic balls do shrink
    after reflow on board.


 

After reflow on board height of balls decrease 
from 0.65 to 0.55 mm due to package weight.
 diameter increase from 0.80 mm to 0.85 mm.
Data for information only. 
It is not an e2v specification
  • in case of Sn10Pb90 columns, the columns do not melt
    with the Sn63Pb37 solder and are not modified by the
    PCB mounting process.