Packaging Parameter Analysis on Solder Joint Reliability for Twin Die Stacked Packages by Variance in Strain Energy Density of Each Solder Joint

In this paper, the ANSYS 7.0 software is applied to analyze a twin die stacked package under a cyclic thermal loading condition. The viscoplastic finite element analysis and the Darveaux theory are applied to investigate the solder joint reliability of the stacked die package. Accordingly, a significant dependence between the fatigue life of the solder joint for the stacked die package and the distribution of the accumulated strain energy density on the solder is verified by proposing a viewpoint of the variance of the strain energy density among solders in accordance with a 3-D slice model. As a result, for enhancing solder joint reliability of the twin die stacked package, it is found that thinner top die, thicker bottom die, thicker substrate, and thinner PCB are preferred in the aspect of geometry configurations; while the coefficient of thermal expansion (CTE) of molding compound near upon CTE of substrate which causes minimum package warpage, and lower molding compound Young's modulus and lower substrate Young's modulus are preferred in the aspect of material properties