A stand-alone active thermal interposer device for use in testing a system-in-package device under test (DUT), the active thermal interposer device includes a body layer having a first surface and a second surface, wherein the first surface is operable to be disposed adjacent to a cold plate, and a plurality of heating zones defined across a second surface of the body layer, the plurality of heating zones operable to be controlled by a thermal controller to selectively heat and maintain respective temperatures thereof, the plurality of heating zones operable to heat a plurality of areas of the DUT when the second surface of the body layer is disposed adjacent to an interface surface of the DUT during testing of the DUT.