Abstract: A structure and a method provide an assembly for receiving an integrated circuit die. The assembly comprises a heat sink selectively coated with electrically insulative material. The heat sink is attached by one of various methods directly on to the integrated circuit die and a lead frame for external electrical connections. The heat sink is formed as a stepped structure to increase the path of moisture penetration so as to improve moisture resistance and reliability. In one embodiment of the present invention, the electrically insulative material comprises anodized aluminum, which is formed on the heat sink by a vapor deposition step, followed by a hard anodization step. Other electrical insulative material which can be thinly applied on the surface of the heat sink are non-conductive resins and polymers. The heat sink is formed out of copper or a copper alloy, selected for strength and electrical and thermal conductivities.