嵌入式微通道传热特性及局部热点尺度效应

通过实验测试结合理论分析，研究嵌入式微通道冷却系统的传热特性及局部热点的尺度效应. 测试芯片加工采用MEMS工艺，微通道层与顶层之间的连接采用硅硅直接键合，芯片与电路板（PCB）之间的连接采用倒装焊接. 研究结果表明，采用嵌入式微通道设计极大地缩短了微芯片到微通道的导热距离，可以显著地减小微芯片到环境的热阻. 根据测试结果可知，在100 W/cm²均匀热流密度的条件下，使用6.84 mW/cm²的泵功，可以将模拟IC热源的温升控制到小于40 K，能效比超过14 000. 在非均匀热流密度的条件下，局部热点的存在会增大导热热阻在总热阻中的占比，局部热点尺度越小，热点附近的侧向热传导越严重，导热热阻越大，这减小了对流换热热阻在热点区域总热阻中的占比，使得增大对流换热系数带来的总热阻降低效果减弱.

Heat transfer performance and scale effect of hot spots in embedded microchannel cooling system

An experimental and theoretical study was presented to analyze the heat transfer performance and the scale effect of hot spots in embedded microchannel liquid cooling system. MEMS micromachining was used to fabricate the test chip, silicon-to-silicon direct bonding was used to bond the microchannel layer to the silicon cover, and Flip-chip bonding was used to bond the test chip to a printed circuit board. Results show that the embedded-microchannel design greatly reduces the thermal conduction distance from the microchip to the microchannel, resulting in a low thermal resistance from the microchip to environment. The test results show that the temperature rise of the simulated IC under a uniform heat flux of 100 W/cm² can be controlled within 40 K using only 6.84 mW/cm² of pumping power with a coefficient of performance exceeding 14 000. The existence of hot spots increases the proportion of the heat conduction resistance in the total thermal resistance of the hot spot area under a non-uniform heat flux. The smaller the size of the hot spot area was, the more serious the lateral heat conduction was and the thermal conduction resistance became larger, which indirectly reduced the proportion of the heat convection resistance in the total thermal resistance of the hot spot area. Then the benefit of increasing the convective heat transfer coefficient on decreasing the total thermal resistance of the hot spot area was decreased.