Structural stress analysis of infrared detector with underfill

Abstract

To reduce the probability of InSb infrared detector cracking during its temperature drops quickly, for InSb detector with underfill, here ANSYS, is employed to research the impacts from both indium bump diameters and heights on both Von Mises stress and its distribution. Simulation results show that as the diameters of indium bump decreases from 36µm to 24µm in step of 2µm with fixed indium bump thickness, the maximal Von Mises stress of InSb chip decreases firstly, then increases, and when the indium bump height and diameters are set to 24µm, 21µm respectively, Von Mises stress in the InSb chip reaches minimum, and on all contacting areas between InSb chip and indium bump array, its distribution is uniform and concentrated. However the maximal Von Mises stress of indium bump keeps at 16.57MPa or so, and is the smallest in the whole device. Von Mises stress of Si readout integrated circuits is also much smaller than that of InSb chip, and do not show obvious variation regularity.