Development of thin loop heat pipe for compact electronics

• The novel LHP design offers effective heat transfer for compact electronics. • Filling ratio of 58% shows optimal thermal performance among configurations. • Operates up to 8 W/cm 2 regardless of gravity orientation, enhancing flexibility. • Thinner channel height increases pressure drops, reducing thermal performance. • External plate thickness impacts heat leakage, suggesting room for improvement. This study experimentally evaluates the thermal performance of a thin diffusion-bonded loop heat pipe (LHP) designed for electronics cooling applications. The device represents the third generation of an LHP with the same top-view dimensions of 76 x 60 mm 2 and an identical wick structure. However, the thickness has been progressively reduced from 1.6 mm to 1.1 mm, and now to 0.8 mm. Despite this reduction, the LHP demonstrates good thermal performance. An advanced testing workbench, simulating actual electronic operating conditions, enables performance evaluation in horizontal, gravity-assisted, and against-gravity orientations. The evaporator and part of the condenser incorporate a sintered copper powder wick structure. While the lowest thermal resistance of 2.16 °C/W is observed in the gravity-assisted orientation, the LHP operates nearly independent of gravitational effects, exhibiting comparable thermal resistances in all orientations. The reduction in internal channel thickness led to an average decrease of 50 % in thermal performance compared to previous generations with thicker channels (1 mm and 0.5 mm). Nonetheless, the current LHP remains highly suitable for electronic applications due to its thin profile, efficiency, and ability to dissipate up to 8 W/cm 2 without exceeding the maximum operating temperature of 100 °C.