In order to learn the effects of front surface structural defects and back surface thinning process on the InSb chip deformation, its elastic modulus along normal direction is reduced in InSb structural modeling, and based on the typical strain character appearing under thermal shock, the mechanical parameter selection basis is deduced in this paper. Simulation results show that when the out-of-plane elastic modulus of InSb chip is set to be 30 percent Young's modulus, both the maximum Von Mises stress and Z component of strain appear in the N electrode zone, and the extremum values present non-continuous distribution. These are in good agreement with fracture origination zone and crack distribution in the fracture statistics results of 128 128 InSb infrared focal plane array under thermal shock. Besides, the region above the indium bump array is convex upward, and the domain above the isolation trough is concave downward, they are also identical with the scenario of Z component of strain in InSb chip under thermal shock. All these results indicate that the Z component of strain criterion can not only predict both crack origination zone and crack distribution, but also support both Z component of strain distribution in the central region and Z component of strain enhancement effect in the InSb chip N electrode zone.