A semiconductor package assembly is presented. The assembly comprises a first chip and a second chip. The back surfaces of the first and the second chips are thermally attached through a die attach material. The front surface of the first chip is attached to a substrate through bumps. A heat spreader extends from a surface of the semiconductor package assembly into the semiconductor package assembly and thermally attaches to the back surface of the first chip or the front surface of the second chip. Depending on the sizes of the chips and the location of the bonding pads, the heat spreader may be attached to the back surface of the first chip or the front surface of the second chip.