Board Design Influence on BGA Mechanical Reliability

With the technology trend moving towards faster, smaller, and cheaper products, the consumer electronics industry is using more and more high density fine pitch BGA components in a lead-free environment. This has created additional board-level solder joint mechanical reliability challenges. Current literature studies mostly focus on the impact of component design features on BGA solder joint reliability. Very little information is available on board design factor impact on BGA mechanical reliability. This paper highlights the results of our study on the sensitivity of three critical board assembly design factors on BGA solder joint interconnect reliability under mechanical shipping stresses. The results from this study showed high sensitivity to the component location on the board, board trace routing orientation under the component, component enabling heat sink retention mechanism design, and neighboring component heat sink mass. The data collection also showed multiple failure modes including BGA solder joint cracks, PCB pad craters, and PCB trace cracks. Finite element analysis (FEA) modeling results correlated well with empirical data collection and provided additional insight into the physics behind the failures. In conclusion, the paper provides design for reliability (DFR) recommendations to proactively identify high risk bend-line zones to prevent BGA and PCB failures through predictive modeling. This methodology enables board designers to optimize electrical and thermal design and build a mechanically reliable product.