Structural Stress Analysis of 32x32 InSb Infrared Focal Plane Array with Underfill

ABSTRACT

Based on viscoplastic Anand,s model, the structural stress of 8x8 InSb infrared focal plane array detector with underfill is systematically analyzed by finite element method, and the impacts of design parameters including indium bump diameters, heights on both Von Mises stress and its distribution are discussed in this manuscript. Simulation results show that for the given indium bump height, the maximum stress existing in InSb chip is almost unchanged with reduced indium bump diameters, and with thicker indium bump, the stress is smaller, when the indium bump height is over than 15xm, the stress reduces slowly with decreased standing off height. When the InSb IRFPA format increases from 8x8 to 32x32, the maximal Von Mises stress increases from 500MPa to 900Mpa, almost twice over, and is not proportional to array format scale.