Finite Element Modelling (FEM) of Green Electronics in Aeronautical and Military Communication Systems (GEAMCOS)

As part of the European LIFE project GEAMCOS, this paper presents the simulation evaluation of lead-free electronic assemblies submitted to harsh environments encountered in aeronautical and military communication applications. It addresses the following questions: (1) the determination of an optimal accelerated test condition in the temperature range of -40degC/100degC for assemblies with SnAgCu alloy, (2) the evaluation of the life-time of five assemblies with SnAgCu and SnPb, (3) a sensitivity analysis on design and serigraphy parameter variations, (4) the determination of a test protocol in vibration environments. All the results give relevant life-time predictions. The CSP and PQFP components should have longer time-to- failure with SnAgCu solder joints than with SnPb joints. The contrary is expected for 1st and 2nd level interconnects of large BGA packages. In any case, the factor is found to remain less than about 2. The PCB thermal expansion coefficient has the highest impact, followed by the solder joint height. The first level interconnect reliability is not impacted by any of the parameter changes. Simulation work in GEAMCOS project shall go on in 2007-2008 with an experimental validation of the thermo- mechanical simulations. This will require to identify a new constitutive material model for SnAgCu and to calibrate the simulations with experimental test results.