In order to study the causes and characteristics of indium bump defects in infrared focal plane arrays ( IRFPA) , during the fabrication of InSb IRFPAs, indium bumps of different pixel sizes were studied using positive photoresist. Then, the surface morphology of the chip, the connectivity of the detector, and the performance of the detector were characterized using an optical microscope and an FPA test stand, respectively. The results show that the chip surface and detector connectivity of the 50μm × 50 μm pixel size sample is better than other chips. Due to the small pixel size, the surface topography of the chip is connected or missing to the defective indium bump. The connectivity test results are consistent with the test results of the indium raised surface topography. The connected defects are due to the surface of the indium bumps caused by indium remnants during lithography and stripping.The missing defects are due to the lack of elemental indium bumps caused by positive photoresist residual during photolithography. The response voltage of the connected faulty component is basically the same as the response voltage of the normal component. The response voltage of the defect defective element is zero, and the response voltage of the nearest neighbor element is increased by about 25%compared with the normal element. The result has important reference significance for improving the performance of the FPA detectors by optimizing the production process.