Fabrication and experimental investigation of innovative sintered very thin copper heat pipes for electronics applications

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 package, with an integrated heat exchanger (very thin flat heat pipe), in order to evacuate the required total power losses of 35 W. The potential applications are envisioned in the aviation sector. The paper describes the heat pipe fabrication processes and the experimental investigation conducted to determine the thermal behaviour of the heat pipe. The evaluated heat pipe contains an innovative wick structure (rectangular channels machined in the sintered copper spheres). Several thermal tests were effectuated to study its thermal performances and functioning limits. Using an infrared thermal imaging unit, the temperature gradients and maximum localized temperatures were measured and an effective thermal conductivity was computed. The experimental results were compared with those obtained for a plain copper substrate and indicated that incorporating heat pipes in the metallic substrate as an integral part, could significantly decrease the temperature gradients occurring across the substrate, increase its effective thermal conductivity and decrease the maximum chip temperatures