Biomimetic Copper Forest Wick Enables High Thermal Conductivity Ultrathin Heat Pipe

Electronic devices with high heat flux are currently facing heat dissipation problems. Heat pipes can be used as efficient heat spreaders to address this critical problem. However, as electronic devices become smaller, the space for heat dissipation is becoming ever so limited; hence, ultrathin heat pipes are desired. This study proposes a biomimetic copper forest wick for an ultrathin heat pipe (UTHP). It is made by a simple one-step electrodeposition process and appears as a natural forest structure with abundant Ω-like grooves. Capillary rise tests with ethanol were performed to characterize the capillary force of the wick structure. Compared to traditional sintered particles, this wick structure has a much higher capillary performance parameter, K/R_eff. The biomimetic copper forest wick was used to fabricate a 0.6 mm thick UTHP. The UTHP was tested at different filling ratios; the optimum filling ratio was found to be about 71%. At a heating power of 6 W, the temperature difference between the condenser and evaporator was only 1.2 °C, with an effective thermal conductivity, λ_eff, up to 1.26 × 10⁴ W m^-1 K^-1.