IMMERSION COOLING OF MICROELECTRONIC CHIP WITH MICROCONFIGURED SURFACE

虽然最近的发展使芯片级的散热率大大降低，但随着电子器件封装密度和开关速度的提高，很明显，芯片级的散热率将再次上升到一个较高的水平。利用介质液体直接浸没冷却电子器件是一种很有前途的方法，因为它具有很高的冷却潜力。然而，这并没有在实际中使用，主要是因为与使用具有高润湿性的介质液体相关联的沸腾起始所需的壁面过热度较高。在本研究中，对FC-72从新开发的具有微重入腔的处理表面的沸腾换热进行了实验研究。表面结构是利用微电子制造技术在硅片上制作的。三种腔口直径(1.6Itam、3um和9um)和两个Num…组合的几种处理表面在表面光滑的情况下，测试了更多的BER密度(8I 1/cm^2和96CHI 10^31/cm^2)。实验是在3K和25K的液体过冷度下用脱气和气溶的FC-72进行的。结果表明：(1)沸腾初期壁面过热度强烈依赖于溶解气体含量，而空腔口直径和液体过冷度对壁面过热度影响不大。(2)对于脱气FC-72，沸腾初期壁面过热度普遍高于非均相成核理论的预测，该理论假定空腔口有一个胚胎气泡的力平衡。这表明，对于润湿性较高的液体，即使是1.6um这样的小开口凹腔也是不活跃的。(3)微凹腔硅片的换热性能比光滑芯片有很大的改善。(4)气溶型FC-72的换热性能高于脱气FC-72。较少

Although the recent developments of CMOS technology has resulted in a considerable decrease in the chip-level heat dissipation rate, it is obvious that the heat dissipation rate will increase again to a high level as the packaging density and switching speed of the electronic devices increase. Direct immersion cooling of electronic devices by use of dielectric liquids has been a promising method because of its high cooling potential. However, this is not in practical use mainly due to a high wall superheat required for boiling incipience associated with the use of dielectric liquids with a high wettability.In the present reasearch, boiling heat transfer of FC-72 from newly developed treated surfaces with micro-reentrant cavities was studied experimentally. The surface structure was fabricated on a silicon chip by use of microelectronic fabrication techniques. Several kinds of treated surfaces with the combinations of three cavity mouth diameters (1.6 IOTAm, 3 mum and 9 mum) and two num … More ber densities of the micro-reentrant cavities (8I 1/cm^2 and 96CHI 10^3 1/cm^2) were tested along with a smooth surface. Experiments were conducted at the liquid subcoolings of 3 K and 25 K with degassed and gas-dissolved FC-72. The results were as follows :(1)While the wall superheat at boiling incipience was strongly dependent on the dissolved gas content, it was little affected by the cavity mouth diameter and the liquid subcooling.(2)For the degassed FC-72, the boiling incipience superheat was generally higher than the prediction of the heterogeneous nucleation theory which assumed the force balance of an embryonic bubble at the cavity mouth. This suggest that even the reentrant cavity with small mouth such as 1.6 mum is inactive for the liquid with high wettability.(3)The heat transfer performance of the silicon chip with micro-reentrant cavities was considerably improved over the smooth chip.(4)The heat transfer performance of the gas-dissolved FC-72 was higher than that of the degassed FC-72. Less