Modeling BGA Solder Joint Distortion Due to Warpage


This video illustrates how corner balls on BGA packages tend to elongate into hourglass shapes during reflow soldering.  We use Surface Evolver TM to model the shape change and hope to further study instability that can lead to head-on-pillow defects. The center balls compress due to the same package warpage strain that elongates the corner balls.  In extreme cases, this can lead to shorted signals and flux entrapment near the center of the BGA.  Analysis of this type can help to prevent defects in production hardware.

See also related work:
BGA assembly validation 
BGA solder joint microsections
Calculating BGA warpage




Edward Hare, PhD and Stephanie Hare, PhD