A capillary-pumped loop (CPL) with microcone-shaped capillary structure for cooling electronic devices

摘要

A MEMS-based integrated capillary-pumped loop (CPL), which can be used for cooling electronic devices such as the CPU of a personal computer or notebook, was developed. The CPL consists of an evaporator and condenser both with the same size of 30 mm × 30 mm × 5.15 mm, which were fabricated using two layers of glass wafer and one layer of silicon wafer. A key element of the CPL is that the 480 ± 15 μm thickness silicon wafer where an array of 56 × 56 cone-shaped microholes that generates the capillary forces was fabricated and inserted above the compensation cavity for liquid transportation instead of a porous wick in the evaporator. The same cone-shaped microstructure was used in the condenser to create a stable interface between the liquid and vapor phases. The CPL fabricated was tested under various conditions such as different relative heights, fill ratios and heat fluxes. The operation conditions of the CPL were varied according to the relative height and fill ratios. With an allowable temperature of 110℃ on the evaporator surfaces, the CPL can handle a heat flux of about 6.22 W cm{sup}(-2) for the air-cooled condenser. Steady-state operation conditions were achieved within 10 min.