There is a growing demand for power electronics that can operate under the high temperature and high power conditions that will be encountered in Hybrid Electric Vehicles (HEV). As the coolant temperature used to dissipate heat from electronics increases, the operation of power semiconductor devices such as Insulated Gate Bipolar Transistors (IGBTs) becomes severely limited in order that the safe operating temperature limit of the semiconductor devices not be exceeded. There is a need for high efficiency low-cost heat sink technology to support next generation high power, high reliability HEV IGBT power modules. The proposed effort is focused on the development of a unique, high efficiency integrated package and heat sink technology for application to IGBT power modules. The heat sink is enabled by a dielectric-graphite-metal composite material which provides for electrical isolation of the electronic components and circuitry, minimizes the thermal resistance between the electronics and the heat sink fluid and provides CTE matching of the composite material stack-up to minimize thermal stresses resulting from power and temperature cycling. There is a critical need for advanced active cooling solutions with improved thermal properties capable of meeting the thermal management requirements of current and future high power HEV IGBT modules. The research objectives of this project are the development of the design and manufacturing process for the components of the proposed heat sink assembly; and the demonstration of the heat sink