Infrared lock-in thermography (IR-LIT) is a fault localization technique that serves the purpose of detecting a local heat source or hotspot emitted by the faulty area. Performing backside hotspot localization overcomes the limitation during frontside hotspot localization, especially for shorted areas that emit a low heat source. In order to produce better hotspot localization from the package backside, it is important to study more of the factors affecting backside hotspot localization, including the power settings of the device, the lock-in frequency, and the die thickness of the packages. Power packages are inspected using a tool with varying power and frequency settings. The results are collected by observing the size of the hotspot and by recording the time taken for the hotspot to appear. To investigate the die thickness, the die surface is grinded from the backside of the die and the thickness of the die was measured using x-rays. The relationship between the power settings, the frequency settings, and the die thickness does show significant changes to the hotspot size and the time taken to generate a hotspot.