A compliant thermal spreader with internal liquid metal cooling channels

This paper describes a 1 mm thick substrate with integrated flow channels to circulate liquid metal that is pumped with an electromagnetic pump. The substrate was fabricated using conventional circuit board assembly methods. Tests were performed with pumping current of up to 10 amps, which corresponded to a pumping power of 450 mW. This testing showed that the substrate had an effective thermal conductivity of more than 6000 W/mK. The thin geometry and organic circuit board materials of the substrate allow it to be mechanically compliant and therefore can reduce the need for thermal gap fillers to connect dissipating components to the thermal spreader.