Modeling thermal cycling and thermal shock tests for FCOB

Finite element modeling and simulation of thermal cycling and thermal shock tests for Flip-Chip-On-Board (FCOB) solder joint life prediction was conducted. Firstly, a phenomenological approach using an elastic-plastic-creep analysis model simulates time independent plasticity and time dependent creep deformations in the solder joints. Temperature and strain rate dependent properties for eutectic solder (63Sn/37Pb) were incorporated into the finite element models. Secondly, a state-variable approach using a viscoplastic analysis based on the Anand model simulates the strain rate dependent inelastic deformations in the solder joints. Thermal cycling and thermal shock loading for -50 C to +150 C were investigated for ramp rates of 10 C/min and 100 C/min respectively. Solder joint fatigue models were used for life prediction analysis employing the inelastic strain range and inelastic energy density parameters derived from the finite element results.