Immersion Cooling for High-Density Packaging

New cooling techniques using direct immersion cooling for high-density packaging are discussed, focussing on a) the treatment of bubbles produced by nucleate boiling and b) the control of coolant composition to prevent "temperature overshoot" occurring at the boiling point as thermal hysteresis. Maintaining subcool boiling (the initial stage of nucleate boiling) until maximum power application is a useful cooling technique in high-density packaging of computers because this technique produces fewer troubles than saturated boiling. The module model, which incorporated subcool boiling, showed a high cooling capability of 10 W/cm²at the chips, and 1.0 kW for the 900-cm³module volume. Controlling coolant composition produces azeotropic boiling which, in turn, prevents temperature overshoot.