Board level drop tests comparing lead-free and eutectic solder interconnects on a BGA package for mobile ICT applications

There is considerable reported evidence that a large percentage of failures which afflict portable electronic products are due to impact or shock during use. Failures of the external housing, internal electronic components, package-to-board interconnects, and liquid crystal display panels may occur as the result of accidental drops. Moreover, the introduction of lead-free solder to the electronics industry will bring additional design implications for future generations of mobile information and communication technology (ICT) applications. In this paper, drop tests performed on printed circuit boards (PCBs) populated with ball grid arrays (BGAs) are reported. During testing, measurements from strain gages were recorded using a high-speed data acquisition system. Electrical continuity through each package was monitored during the impact event in order to detect failure of package-to-board interconnects. Life distributions were established for both lead-free and eutectic solders for various drop heights. Microsections of the failed interconnects were obtained to determine the failure mechanisms for a range of drop heights. The life test data presented in this paper suggests that for board level drop testing different failure mechanisms can occur at different stress levels and that there is a considerable difference between lead-free solder characteristic life and tin-lead (SAC) solder characteristic life.