Passivation cracking is one of the main failures of Integrated Circuits (ICs) and thermo-mechanical failures are the root cause. A major cause for these failures is due to the mismatch of thermal and mechanical parameters while manufacturing or working, especially stress concentration at the interface and the edge. The ICs for different fixing position endure different thermal cycles, overload and vibrations under the aeronautical working conditions. Therefore, the different fixing position is expected to have a pronounced influence onthe stress distribution in the passivation layers. In this paper, the finite element simulations and the maximum principal stress theory are applied to investigate the effects of different fixing position on the passivation cracking of ICs under aeronautical working conditions. The result will provide a deeper understanding of how to optimizae the structure and improve the reliability of IC microstructures package design.@en