A semiconductor package structure with a heat dissipating stiffener and method of fabricating the same are provided. In one embodiment, the package structure comprises a substrate having a front side and a back side; a semiconductor chip mounted on the front surface of the substrate; a thermally-conductive stiffener mounted over the front surface of the substrate and surrounding the chip, the stiffener having a first portion and a second portion, wherein the first portion is wider than the second portion so as to allow for easy egress of a dispenser into a gap between the chip and the substrate; an underfill layer filled and cured in the gap; and a plurality of solder balls mounted on the back surface of the substrate.