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Finite Element Analysis was conducted to assess the response of the ball grid array (BGA) package to a relaxation in its coplanarity specifications as part of efforts to align with JEDEC standards. Using the BGA492 package as vehicle, the coplanarity specification was relaxed from 6 mils to 8 mils. The comparative analysis embodied in this paper focused on solder joint reliability under thermal cycling. Based on the reliability data gathered and finite element modeling and analysis, an approximate 10% reduction in solder joint life (number of cycles used) was predicted. Nonetheless, results on actual reliability stressing on BGA packages with 8-mil coplanarity specification showed no solder joint failures even after 2000 temp cycles, versus the reliability testing requirement of only 1500 cycles.
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