Abstract: A semiconductor package with a heat sink is provided in which at least one chip is mounted on the substrate and covered by a heat sink. The heat sink is formed with a flange in contact with the substrate, allowing a plurality of clip members to clamp the flange of the heat sink and the substrate. Each of the clip members has a recess portion for receiving the flange of the heat sink and the substrate to thereby firmly position the heat sink on the substrate. The clip members are engaged with edges of the heat sink and the substrate, thereby not affecting trace routability on the substrate. Moreover, the heat sink is mounted on the substrate and would not be dislocated.