Finite Element Analysis on Structural Stress of 8×8 InSb Infrared Focal Plane Array with Underfill
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 the maximum stress existing in InSb chip reaches minimum with indium bump diameter 32μm. Under this condition, for the fixed indium height, as the InSb chip thickness reduces from 21µm to 9µm in step of 3µm, Von Mises stress maximum values of InSb chip seems increases gradually, and when the indium bump height reduces from 21µm to 9µm in step of 3µm, its maximum Von Mises stress increase at random increment, do not show certain rules, and indium bump height seems to have a comparable effect on stress value with InSb chip thickness. When indium diameter, height and InSb chip thickness are set to 32µm, 15µm, and 12µm, respectively, the maximal Von Mises value existing in InSb chip reaches minimal value 628MPa, simultaneously the stress distribution at the contacts areas is uniform and concentrated, and this structure is promising to avoid device invalidation.
Daoguo Yang, Tianlong Gu, Huaiying Zhou, Jianmin Zeng and Zhengyi Jiang
Q. D. Meng et al., "Finite Element Analysis on Structural Stress of 8×8 InSb Infrared Focal Plane Array with Underfill", Advanced Materials Research, Vols. 201-203, pp. 108-112, 2011