Spacecraft Thermal Management Solutions Using Annealed Pyrolytic Graphite

Introduction As in the rest of the electronics world, the range of applications and functions of satellite systems is rapidly advancing. Applications such as phased array radars, satellite communication links, sensor systems, inter alia, combined with new packaging technologies and devices like multi-chip modules, high-density batteries, and high-speed processors have increased the technical challenges in packaging these systems. Combined with the quest for miniaturization, the power densities of electronic systems are rapidly increasing raising device temperatures to intolerable levels. Managing these high packaging densities and their corresponding high power dissipations requires the use of thermal systems capable of maintaining device temperatures below critical levels. Satellite systems have the additional the challenges of a harsh vacuum environment (no convection cooling) and requiring low mass solutions. A vital part of the space vehicle design, the thermal control subsystem must maintain all components at or below specified allowable operational temperature limits when exposed to external thermal environments. Alternative advanced thermal materials are needed to meet future spacecraft thermal radiator subsystem requirements. Encapsulated annealed pyrolytic graphite is a material system that can satisfy many of the packaging requirements of such systems. A novel, patented technique of encapsulating annealed pyrolytic graphite (APG) within a structural shell has been developed. Named k-Core, the encapsulated APG composite is an ideal thermal management material because of its high thermal conductivity (up to 1400. W/mK), low mass density (as low as 1.9 g/cm), high stiffness (up to 50 Msi), and the ability to have an engineered coefficient of thermal expansion. This material has been used in a variety of applications and form factors from large radiator panels to small electronic substrates. Presented herein is an overview of this material systems with examples of how it is used.