Enhanced Cooling of Electronic Chips Using Combined Diamond Coating and Microfluidics

We investigate the impact of the combined diamond heat-spreading layer and microfluidic convection on the performance of a model electronic chip heated locally. Experiments are carried out and a finite element method is used to simulate the thermal response of the device under transient step-wise (without flow) and steady-state (with flow) operation conditions up to heat flux values of 38 and 190 W/cm(2), respectively. In all cases, the temperature on the heated outer silicon surface did not exceed 100 degrees C. The temperature field contour has an oval shape for transient heating without flow and a funnel shape for steady-state heating with flow. For a step-wise heat flux of 38 W/cm(2), the differences between temperatures at the center of the resistor and at the outer surface edge after a time interval of 8 s are 5, 3, and 1 degrees C for the chips without a diamond layer, with a 100-mu m diamond layer, and only a 400-mu m diamond, respectively, which proves the enhanced spreading due to the diamond layer. Under steady-state conditions at a heat flux of 190 W/cm(2) and volumetric flow rates of water between 2 and 5 ml/min, the surface temperature decreases by approximately15% for silicon wafer with a 100-mu mdiamond layer and by approximately 22% for a 400-mu m diamond as compared to heating without the addition of diamond. Of crucial importance is the proximity of the diamond layer to the heat source, which makes this method advantageous over other thermal management procedures, especially for pulsed operating conditions and hot spots.