A heat sink pedestal device allows for the use of generic thermal units such as heat sinks. An interposer configured to fit a specific device under test is mounted to a retainer. The retainer firmly holds the interposer in position. In addition, the retainer may be mounted to a thermal unit. An interface sealant with a diameter less than that of the interposer, creating the perimeter of an interface medium chamber, is positioned at the periphery of the interposer between the interposer and the thermal unit. Interface material, having high thermal conductive properties, is positioned within the interface sealant. The interface medium chamber provides a high thermally conductive interface between the interposer and the thermal unit. In addition, the heat sink pedestal device minimizes customization because it allows a single heat sink or thermal unit assembly to be used to accommodate a wide range of unit sizes.