A method of manufacturing a plurality of stacked die semiconductor packages, including: placing a phase change material between a top surface of a substrate and a bottom surface of a first die; placing a phase change material between a top surface of the first die and a bottom surface of a second die; wherein the first and second dies have a plurality of conductive protrusions on the bottom surfaces of the dies; wherein the first die has a plurality of conductive vias extending from its conductive protrusions, through the first die, to the top surface of the first die; wherein the conductive vias of said first die are in alignment with the conductive protrusions of the second die; and heating the dies and the substrate to cause the second die to become electrically interconnected to the first die and the first die to become electrically connected to the substrate.