Experimental and numerical assessment of board-level temperature cycling performance for PBGA, FBGA and CSP

This paper examines the board-level solder joint reliability of PBGA, FBGA and CSP packages under temperature cycling (TC) condition, both experimentally and numerically. 11 legs of test vehicles including 2 legs of PBGA, 2 legs of FBGA, 2 legs of two-die CSP and 5 legs of single-die CSP, were assembled with different solder ball sizes, mold compound materials, test board thickness, and solder materials, i.e., eutectic Pb-Sn and Sn3Ag0.5Cu. Those assemblies were subject to TC condition using UTAC internal TC chamber and data collection system. Two TC conditions were used, which are -40degC~125degC with 15mins ramp/dwell (TCI) and 0degC~100degC with 10mins ramp/dwell (TC2). For the numerical study, Darveaux´s approach, which uses Anand´s visco-plasticity constitutive model plus fracture mechanics based fatigue model, was used for legs with eutectic 62Sn36Pb2Ag solders; while for Pb-free legs, various publicly available Pb-free constitutive and fatigue models were applied to evaluate their prediction capability.