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Machining of thin metal foils with specially contoured diamond cutting tools allows the production of small and very smooth fluid microflow channels for micro heat exchanger applications. Heat exchanger plate wall thickness, as well as fin dimensions, may be carefully controlled and machined to dimensions on the order of tens of micrometers. The plates are stacked and bonded with the vacuum diffusion process to form a cross-flow, plate-type heat exchanger. These fabrication techniques allow the production of small heat exchangers with a very high volumetric heat transfer coefficient and inherent low weight. The design and fabrication process for a copper-based, cross-flow micro heat exchanger has been developed. The micro heat exchanger provided a volumetric heat transfer coefficient of nearly 45 MW/m³ K under very conservative deisgn and operating conditions. This corresponds to a volumetric capacity …