CTE Matched High Heat Flux Spreader for Space Systems Applications

ABSTRACT:The purpose of the proposed Small Business Innovation Research (SBIR) program is to develop a highly effective heat spreader for future generation high heat flux GaN power amplifiers in satellite systems. Current power amplifiers are limited in output by the heat flux capability of the overall thermal management system. In order to enable higher output devices it is critical to reduce the heat flux on the thermal management system by spreading the heat efficiently across a larger area. ACT proposes a bio-inspired, Coefficient of Thermal Expansion (CTE) matched, structural vapor chamber to achieve the desired thermal spreading. Vapor chambers are highly effective heat spreaders that rely on boiling and condensation of a working fluid to spread heat across large areas. The proposed vapor chamber improves upon current vapor chamber technology in three ways. First, the bio-inspired wick structure reduces the liquid pressure drop through the wick structure and enablse significantly higher heat fluxes to be dissipated. Secondly, the vapor chamber materials of construction are CTE-matched to common semiconductor materials. This enables the power amplifiers to be directly attached to the vapor chamber. Finally, ACT proposes a novel internal locking feature to improve the structural integrity of the vapor chamber.BENEFIT:GaN-based solid state power amplifiers (SSPAs) offer the potential for higher power densities which results in significant reductions in size and weight as well as reductions in overall system cost. GaN SSPA technology has the potential to enable low-cost small satellites where current SSPA technology is major restriction. The proposed technology will enable GaN SSPAs to be utilized in current satellite systems by eliminating the need to redesign the entire thermal management system. If successful, the proposed technology would provide a significantly expedited path towards implementation for GaN SPPA technology in satellite systems. The proposed technology is also well-suited for high heat flux terrestrial applications, like high output laser diode cooling, where existing thermal management systems are being pushed to their limits.