In temperature-aware design, the presence or absence of a heatsink fundamentally changes the thermal behavior with important design implications. In recent years, chip-level infrared (IR) thermal imaging has been gaining popularity in studying thermal phenomena and thermal management, as well as reverse-engineering chip power consumption. Unfortunately, IR thermal imaging needs a peculiar cooling solution, which removes the heatsink and applies an IR-transparent liquid flow over the exposed bare die to carry away the dissipated heat. Because this cooling solution is drastically different from a normal thermal package, its thermal characteristics need to be closely examined. In this paper, we characterize the differences between two cooling configurations—forced air flow over a copper heatsink (AIR-SINK) and laminar oil flow over bare silicon (OILSILICON). For the comparison, we modify the HotSpot thermal model by adding the IR-transparent oil flow and the secondary heat transfe...