As packaging technologies evolve to higher component density, the minimisation of the footprint sizes under Small Sized SMD components is of high interest. However, modifying the footprint design will influence the thermo-mechanical reliability of the solder joints that connect the components to the PCB. The reliability of Small Sized SMD components soldered to a PCB is mainly determined by fatigue of the solder joints, induced by thermal expansion differences between the component and the substrate which occur cyclically with heating and cooling cycles. Using surface evolver software for approximating the solder shape and finite element simulations for calculating the induced plastic deformations in the solder material, the thermal fatigue life has been predicted for those small sized SMD components soldered to FR4 printed circuit boards. The effect of design parameters like protruding length, path size and solder thickness has been investigated in order to optimise the reliability of the package. Using these simulation tools, the number of time consuming and consequently expensive experiments can be reduced to a minimum.
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