A flip chip microelectronic package having a heat spreader is provided. In one embodiment, the microelectronic package comprises a die having a first surface and a second surface, the first surface being coupled to a substrate; a thermal interface material disposed in thermal conductive contact with the second surface of the die; and a heat spreader adapted for dissipating heat from the die, the heat spreader disposed in thermal conductive contact with the thermal interface material. The heat spreader includes a lid having an inner chamber therein defined by a first wall and a second wall, the second wall securely joined to the first wall to seal the chamber, the lid being mounted to the substrate and a wick layer positioned in the chamber.