Patent ID: 8390112

Claim:
A microelectronic package comprising: a package substrate; an integrated circuit (IC) die mounted to the substrate; and an integrated heat spreader (IHS) bonded and thermally coupled to the IC die such that the IC die is between the substrate and the IHS, the IHS being coextensive in its width and in its length with respect to the package substrate, wherein the IHS includes a perimeter rib that extends from a bottom surface of the IHS perpendicularly toward and bonds with a top surface of the package substrate, wherein the perimeter rib includes at least one gap designed to allow underfill material to be flowed in a space between the package substrate and the IHS, wherein the IHS includes a gate that extends inward from the perimeter rib to a location adjacent to the IC die, and wherein the gate physically contacts the substrate and the IHS substantially continuously between the perimeter rib and the IC die, and wherein the space and the at least one gap are substantially filled with underfill material.