Finite element modeling of electronic packages subjected to drop impact

As more electronic products become portable, many product manufacturers have started to pay more attention to the robustness of their products. Finite element (FE) simulation has become increasingly popular in the analysis of products subjected to impact loading. The need for details in a FE mesh is always balanced by considerations of simulation time and available computational resources. In this paper, three commonly used approaches to FE modeling of a ball grid array (BGA) package subjected to drop impact are evaluated. The first model comprises a detailed mesh of the printed circuit board (PCB), integrated circuit (IC) package and interconnecting solder balls using solid three-dimensional (3-D) elements. The degrees of freedom is reduced for the second mesh by using shell elements for the PCB and IC package while retaining the detailed mesh of the solder balls using solid 3-D elements. The third mesh is a further simplification of the second mesh whereby the solder balls are replaced by a single beam element each. The stresses within the solder balls are then obtained in a separate FE analysis of a detailed solder ball mesh using the displacement history of nodes around the beam elements from the previous analysis as inputs. Solder ball stresses from all three meshes were found to differ by as much as 40% although PCB deflection compared favorably.