Fabrication and thermal performance of a thin flat heat pipe with innovative sintered copper wick structure

The goal of this research work is to develop and validate the design of a double-sided electronic substrate, part of a multilayer three-dimensional (3D) package, with an integrated heat exchanger (thin flat heat pipe) in order to evacuate the required total power losses of about 35 W. The paper describes the fabrication processes of a flat heat pipe and the experimental investigation conducted to determine its thermal performance. The evaluated flat heat pipe contains innovative wick structure (rectangular channels machined in sintered copper wick structure). The effects of the amount of the working fluid, pure water, and the working temperature on the thermal performance of the fabricated thin flat heat pipe are presented in this paper. Using an infrared thermal imaging unit, the temperature gradients and maximum localized temperatures were measured and an effective thermal conductivity of the heat pipe was computed. The experimental results were compared with those obtained for a plain copper substrate and indicated that incorporating heat pipes in the very thin metallic substrates as an integral part, could increase the effective thermal conductivity of the substrate and decrease the temperature gradients occurring across the substrate. This research work is a part of the European project "microcooling" and is effectuated in collaboration with Thales Avionics. The potential applications are envisioned in the aviation sector