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Sn3.0Ag0.5Cu solder joints lifetime estimation for electronic assemblies under random vibration

This study presents a method to assess component durability under random vibration according to board design and package specificities.Experimental tests were performed and times-to- failure (TTF) of several components were recorded. Consequently, failure modes of packages were identified. A complete FE (finite element) board model with 3D packages of CICGA (ceramic interposer grid array), PLCC (plastic leaded chip carrier) and FBGA (fine ball grid array) components was built. Dynamic behaviour of the board was adjusted with experimental measurements. Transfer functions in stress in critical solder joints were thus calculated for five components. Finally, a damage estimation, which consists in the generation of time-stress responses, was performed. Rainflow cycle counting, linear summation and Basquin's equation were used to compute the elastic damage accumulation in solder joints. Results were confronted and adjusted with experimental TTF. The method is explained and results are discussed.