PoP prototyping by determination of matter transport effects

The assemblies “PoP” (Package-on-Package) can significantly increase the integration density of microelectronic circuits and systems, by vertically combining discrete semiconductor elements. Related to reliability especially migration phenomena, which are investigated here by simulation and measurements, become more important as the dimension of bumps decreases. To explore the influence of migration phenomena to the lifetime of PoPs a test card for current stress tests was designed. Furthermore, an exploration IMC growth was carried out. For a detailed interpretation of the test results FEM simulations with ANSYS
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were performed. Finally, the results were used to predict the lifetime of the daisy chains and to calculate the activation energy for the IMC formation.