Patent ID: 7015577

Claim:
A flip chip package comprising: a substrate having an upper surface and a lower surface; a flip chip having an active surface and a back surface, wherein the flip chip is mounted on the upper surface of the substrate; a thermal interface material applied on a predetermined part of the back surface of the flip chip; and a heat sink having a first surface, a second surface and at least one opening through the first and second surfaces, wherein the second surface of the heat sink is attached to the thermal interface material, an uncovered region of the back surface of the flip chip aligns with and is exposed through the at least one opening, wherein the uncovered region of the back surface of the flip chip further includes a region uncovered by the thermal interface material, wherein the opening has an inner sidewall above the back surface of the flip chip, and wherein the thermal interface material is extended to the inner sidewall of the heat sink to form a fillet height.