Evaluation of board-level reliability of electronic packages under consecutive drops

In general, the drop reliability of a board-level electronic package is characterized by the number of drops to failure according to a certain failure criterion. This implies that damage of solder joints evolves during each drop and eventually leads to failure. Development of a numerical method capable of obtaining accumulated stresses and strains under consecutive drop conditions is therefore in need because without these damage factors, accurate predictions for the board-level drop reliability of electronic packages are unattainable. We implement in this paper the support excitation scheme incorporated with the implicit time integration scheme to study transient structural responses of a board-level chip-scale package subjected to consecutive drops. Accumulated stresses, plastic strains, and plastic strain energy densities on the solder joints under repetitive drop impacts are investigated.