Measuring the Thermal Resistance of Minichannel Cold Plates

The trend towards ever higher power dissipation rates has pushed liquid-cooled cold plate designers to look for more effective methods and structures to transfer heat from device to liquid.

The heat dissipation level of a liquid-cooled cold plate is determined by the heat conduction in solids and the heat convection in fluids. Normally convection is the dominant factor for reducing the thermal resistance when highly conductive material is used to fabricate the heat sinks. In most cases, the single-phase flow inside minichannels is a laminar flow.

For high performance cold plates, the R_caloric will be an important factor on overall thermal resistance, besides convection thermal resistance. The only way to reduce it is by increasing the liquid flow rate, which will lead to more pressure drop and this then requires a better pump. When designing a cutting edge cold plate, engineers should pay a lot of attention to pressure drop, pumping power, system complexity and reliability while pursuing high performance.