Finite Element Analysis on Structural Stress of 8×8 InSb Infrared Focal Plane Array
Based on viscoplastic Anand’s model, the structural stress of 8×8 InSb infrared focal plane array (IRFPA) detector is systemically analyzed by finite element method, and the impacts of design parameters including indium bump diameters, heights and InSb chip thicknesses on both von Mises stress and its distribution are discussed in this manuscript. Simulation results show that as the diameters of indium bump decreases from 36 μm to 24 μm in step of 2 μm, the maximum stress existing in InSb chip reduces first, increases then linearly with reduced indium bump diameters, and reaches minimum with indium bump diameter 30 μm, the stress distribution at the contacts areas is uniform and concentrated. Furthermore, the varied tendency has nothing to do with indium bump standoff height. With indium bump diameter 30 μm, as the thickness of InSb chip reduces from 21 μm to 9 μm in step of 3 μm, the varying tendency of the maximum stress value in InSb chip is just like the letter U, as the indium bump thickness decreases also from 21 μm to 6 μm in step of 3 μm, the maximum stress in 8×8 InSb IRPFA decreases from 260 MPa to 102 MPa, which is the smallest von Mises stress value obtained with the indium diameter 30 μm, thickness 9 μm and InSb thickness 12 μm.
Shengyi Li, Yingchun Liu, Rongbo Zhu, Hongguang Li, Wensi Ding
Q. D. Meng et al., "Finite Element Analysis on Structural Stress of 8×8 InSb Infrared Focal Plane Array", Applied Mechanics and Materials, Vols. 34-35, pp. 207-211, 2010