DIRECT ON-CHIP COOLING OF HETEROGENEOUSLY INTEGRATED PACKAGES USING SINGLE AND TWO-PHASE JET IMPINGEMENT

This work proposes single and two-phase jet impingement cooling as a potential thermal management technique for data center server chips which pose the challenge of thermal coupling apart from the self-heating. First of its kind experimental demonstrations for single and two phase direct-on chip jet impingement cooling of multichip packages are developed and discussed. Using single phase jet impingement, logic chip powers as high as 1700W (TDP = 1.86 kW) were dissipated while keeping its temperature below 105℃. Up to 40W of HBM power was also simultaneously dissipated in the four HBMs each with maximum temperature being 65℃ (against the maximum allowable temperature of 85℃). The minimum thermal resistance for logic chip and HBMs were evaluated to be 0.183 cm².K/W and 0.42 cm².K/W respectively at a cooler pressure drop of 48.32 kPa using water. Replacing water with R1233zd(E) refrigerant, two-phase cooling was achieved for all five chips simultaneously. Individual boiling curves under various operating conditions are also extracted to understand the influence of HBM dissipation on logic chip boiling curve. Power dissipation in HBMs did not affect the CHF for logic chip and thus a maximum heat flux of 66.32 W/cm² and 45W/cm² were dissipated in the logic chip and HBMs. Maximum two-phase heat transfer coefficient of 15,500 cm².K/W and 12,000 cm².K/W was achieved for the logic chip and HBMs at a cooler pressure drop of 28.1 kPa. With R1233zd(E) refrigerant, the corresponding minimal thermal resistance for logic chip and HBMs under the two-phase jet cooling were 0.645 cm².K/W and 0.833 cm².K/W respectively.