Simulation assessment of solder joint reliability for fully assembled printed circuit boards

The present study proposes a new coupled empirical, analytic and FEA method to assess with simulation the solder joint fatigue under a thermal cycling load, based on the PCB and component strains. The preprocessing of the full product FEA model (housings and PCBA) and calculation time were reduced to a few days versus several weeks with the classic simulation approach. Indeed, this method does not need to estimate the solder joints plastic strain for each cycle to predict their respective TTF. This reduces the model complexity by avoiding the modelisation of the components solder joints 3D-shapes as well as avoiding the use of the quasi-static simulations. The solder joint low cycle fatigue predictions by this simulation technique are accurate enough to use results in absolute and to virtually validate the PCBA under thermal cycling accelerated test in storage conditions. FEA input data quality has a big impact on reliability prediction. A specific correlation campaign on the PCBA was also performed by TDM measurement which was mandatory for material database development.