Viscoplastic Finite-element Simulation To Predict The Solder Joint Fatigue Life Of Different Flash Memory Die Stacking Architectures

Abstract

This thesis focuses on the viscoplastic finite-element simulation to predict the solder joint fatigue life of different die stacking architectures for flash memory products. Four different stacked package architectures were evaluated as follows: pyramid, rotated, and spacer stacking, while interconnection (solder joint) was held constant. Number of dies for all four stacking configurations were varied from three, five and seven. To keep the package height constant, the die and die attach thickness were varied and the resulting effects on the stresses were investigated. A quarter and half symmetry model of stacked flash package are generated using ANSYS APDL script. The life cycle of the resulting packages were simulated under accelerated temperature cycling conditions (-40C to +125C, 15min ramps/15min dwells).