Local delamination of InSb IRFPAs in liquid nitrogen shock tests

Both the local delamination and the local fracture, appearing in the InSb infrared focal plane arrays (IRFPAs) detectors in liquid nitrogen shock tests, restrict the final yield of the InSb IRFPAs detectors. To explore the mechanism of the local delamination appearing in the region of the negative electrode of the InSb IRFPAs detectors, basing on the created structural modeling of the InSb IRFPAs detectors, we obtain the distributions of the interfacial stresses in the different interfaces of the InSb IRFPAs detectors. After comparing the distributions of the simulated interfacial stresses with the measured local delamination region in the InSb IRFPAs detectors, we think that the local delamination originates from the interfacial shear stresses, and the crack extension is the typical sliding mode. Besides, the weakened gluing strength between the InSb chip and the underfill in the negative electrode region also causes this region to be prone to the local delamination. All these findings provide the theoretical references for both the structure design and the structure optimization of the InSb IRFPAs detectors assembly in the future.