US Patent 7141886 Air pocket resistant semiconductor package

A die is attached to a substrate and is enclosed in a heat spreader, the heat spreader having a first encapsulant guide and a heat spreader air vent in the heat spreader extending therethrough. An encapsulant encapsulates the die, the substrate, at least a portion of the heat spreader, the first encapsulant guide, and the heat spreader air vent such that the encapsulant enters the heat spreader through the first encapsulant guide and air exits the heat spreader through the heat spreader air vent, thus preventing the formation of air pockets under the heat spreader.