Reliability evaluation of stacked die BGA assemblies under mechanical bending loads

Abstract

This thesis presents a reliability evaluation of stacked die ball grid array (BGA) assemblies under mechanical bending loads. The test specimens used in this investigation were four die stacked BGAs assembled on printed circuit boards (PCBs) with eutectic tin-lead solder and gold over nickel finishes, both as-reflowed and after aging. The failure envelopes of both types of specimen were quantified in terms of PCB flexural strain and strain rate. The experimental data from cyclic bending tests at three strain amplitudes with a constant strain rate have been used to determine the effect of strain amplitudes on cycles to failure. The experimental data from cyclic bending tests were combined with the data from impact tests to determine the effect of strain rate to cycles to failure. The failure sites associated with each test condition were identified, and failure site transition phenomena are reported and discussed.