Characterization of Hybrid Wicking Structures for Flexible Vapor Chambers

Thin vapor chambers provide a novel solution to thermal management in mobile electronics. In the pursuit of vapor chamber optimization, characterization of the wicking structure can allow for a better understanding of the limitations of the device. This paper presents two novel testing methods: one for measuring the permeability of various wicking structures and another for measuring the capillary pressure. We find that the permeability of the mesh used in the wicking structure and hybridization of wicking-structures can impact what geometries limit performance, besides impacting performance directly. Specifically, while the permeability of a mesh-pillar hybrid wick follows the weighted average of the mesh and pillar permeability, the capillary pressure is determined by the capillary pore size of just the pillars or just the mesh, whichever is larger.