The signal of IRFPA is an important performance parameter, influenced by various factors. In this paper, based on the Planck’s law and considering multiple influencing factors, the signal value of a specific infrared detector is calculated. Through computation, a strong correlation is identified between the thickness of the chip and the signal of the IRFPA, which is subsequently verified experimentally. During verification, it is observed that when the chip thickness decreases, the signal value decreases to some extent, showing discrepancies with the calculated results. An analysis of these differences is conducted, and both analytical and experimental results reveal that the thinning thickness and thinning process of the detector chip exert significant impacts on detector performance. After secondary verification, the results substantially align with the analytical predictions.