Analytical and experimental investigation on the capillary rise of heterogeneous porous-grooved AlN–Cu ceramic wick structures

The ceramic vapor chamber has garnered significant attention for high-heat-flux dissipation in high-power chips, owing to its thermal expansion coefficient matching that of semiconductor materials. However, its relatively low heat transfer performance limits its widespread application. This study proposes a heterogeneous porous-grooved aluminum nitride–copper (AlN–Cu) ceramic wick structure fabricated via high-temperature solid-state sintering and laser layer-by-layer processing. This morphology aims to significantly enhance the fluid transport capabilities of ceramic vapor chambers. The composite wick architecture comprises macro-scale primary grooves integrated with a micro-scale porous matrix that features sintering necks and multi-scale pore networks. The effects of AlN/Cu particle sizes, copper powder content, and structural parameters on the surface morphology and capillary performance of the wicks were systematically investigated. The results indicate that the copper content significantly influences the surface morphology of the wick. Because copper inherently resists laser ablation, higher concentrations yield micro-pillar structures that disrupt the hydrodynamic uniformity of the grooves, thereby severely degrading the capillary performance. The optimal configuration (100–150 μm particle size, 25% Cu, and 500 μm groove width) establishes a more open liquid transport space, achieving a superior hydrodynamic balance between capillary driving pressure and flow resistance. This optimization establishes a superior hydrodynamic balance between the capillary driving pressure and flow resistance, rendering this configuration the top performer among all tested combinations. As a result, the maximum capillary rise height reaches 40.17 mm, representing a 77% improvement over resistance-dominated small-particle-size groups. Concurrently, the calculated capillary performance parameter (Ka/Reff) exhibits an average increase of 251%.