Ultrathin bent vapor chamber for heat transport across non-coplanar interfaces in microsatellites

High-power electronics in highly integrated microsatellites intended for rapid-response space missions require passive thermal links that can bridge non-coplanar interfaces without substantial mass or thickness penalties. Here, an ultrathin 90° bent vapor chamber (BVC) was developed to connect integrated electronics with a remote radiator. The 0.9 mm-thick, 86.2 g copper device incorporates a vapor core, copper-mesh wick layers, braided copper liquid-return wicks, section-specific internal supports, and a 50 vol% ethanol–water working-fluid mixture. Structural analyses under ambient-pressure collapse, elevated-temperature internal-pressure loading, and mold-assisted bending indicated that the support architecture preserved the predicted vapor-core clearance without excessive shell deformation. Ambient and thermal-vacuum tests demonstrated stable axial heat transport across the bent path, with a maximum overall equivalent thermal conductivity of 5434 W·m -1 ·K -1 . Section-specific temperature-dependent equivalent-conductivity functions were implemented in a microsatellite thermal model. Under representative high- and low-temperature orbital conditions, the simulated mean temperature differences between the integrated electronics and BVC cold end were 12.3 °C and 13.5 °C, respectively. Whole-satellite thermal-vacuum cycling demonstrated repeatable transient coupling, while flight telemetry showed comparable cyclic trends with a maximum cycle-averaged absolute temperature deviation of approximately 4 °C. These results demonstrate that ultrathin bent vapor chambers provide a practical passive heat-transfer option for microsatellite layouts constrained by mass, thickness, and non-coplanar mounting geometry.