PIEZOELECTRIC ACTUATING SPRAYED PHASE-CHANGE COOLING TECHNIQUE FOR VLSI CHIPS

摘要

To develop high performance cooling systems for high heat generation electronic devices, such as CPU, the spray cooling technique using piezoelectric (PZT) actuator in vacuum with its experimental results will be described. The water droplets were ejected through an circular orifice array membrane vibrating at high frequency bending mode which was excited by a ring-shape PZT actuator. Two parts of experiment has been conducted that including the driving conditions for PZT and the heat transfer of the micro scale water droplet. Furthermore, the maximum heat transfer rate has been evaluated at different ambient pressure. The cooling capability at a wide range of operation conditions was measured. The experimental results indicate that the stability of the spray flow rate will affect the heat transfer rate dra- matically. In our experiment, the water was used as the coolant and 30 μm diameter orifice array. At a flow rate of 1.2 ml/min will remove the heat over 50.3 W/cm~2, and the copper surface would be 123.18℃. When vacuum technique is used to reduce the operation pressure to 21.33 kPa, the copper surface temperature can decrease to 85.78℃ at 50.3 W/cm~2 heat flux. The described cooling technique demonstrates competitive potential for next generation cooling for CPU applications.