Finite Element Prediction of Stack-Die Packages under Board Level Drop Test
The objective of this research is to investigate the solder joint reliability of board-level drop test based on the support excitation scheme incorporated with the submodel technique for stacked-die packages. Three lead-free materials, SAC405 (Sn4Ag0.5Cu), SAC355(Sn3.5Ag0.5Cu) and Sn3.5Ag were used to demonstrate the transient dynamic response for solder balls subject to JEDEC pulse-controlled board-level drop test standard. In order to evaluate the structure of the interested area, a strip model sliced from the full test vehicle is used in this research. In addition, the submodel region is particularly chosen with strip model by performing the cut boundary interpolation. The envelope of equivalent stress for the outermost solder joint off the end of the strip model is plot to show the potential failure mode and mechanism. The cut boundary of submodel is verified and the mesh density of submodel is examined. For a refinery mesh of submodel, parametric studies for structure and material are carried out to investigate the reliability of the outermost solder joint, and the results are summarized as design rules for the development of stacked-die packages.
Sheng-Jye Hwang and Sen-Yung Lee
H. C. Hsu et al., "Finite Element Prediction of Stack-Die Packages under Board Level Drop Test", Materials Science Forum, Vol. 594, pp. 169-174, 2008