An integrated circuit package assembly includes a substrate, a semiconductor die having opposing first and second surfaces, and a head-spreader. The semiconductor die is mounted on the substrate with the first surface facing the substrate. The heat-spreader includes a central region thermally coupled to the second surface of the semiconductor die, a flange region mounted on the substrate, and a side wall region between the central and flange regions. A cavity is formed between the heat-spreader, the substrate, and the semiconductor die. The heat-spreader has at least one vent extending from the cavity through the heat-spreader.