Reliability of Lead-Free BGA Assembly: Correlation Between Accelerated Ageing Tests and FE Simulations

In 2006, lead was banished in electrical and electronic equipment in Europe, but the reliability of lead-free technology is not yet well known. This paper describes a methodology using experiments and FE simulations that allow us to assess acceleration coefficients (ACs) and to predict assembly lifetimes. Two accelerated ageing tests have been conducted on lead-free ball grid array (BGA) assemblies. During the ageing test, cycles-to-failure have been accurately determined by an event detector from AnaTech. The 3-D nonlinear finite-element model of the BGA assembly has been designed and built using ANSYS software. Thermomechanical simulations have been carried out on this model to compute the strain energy density (SED) that dissipated in the solder joints during the thermal cycles. Then, the correlation between the experimentations and the simulations has allowed us to assess the ACs of two different kinds of thermal cycles and, thus, the cycles-to-failure for another test.