A cold plate is used to cool a 2˝ x 4˝ IGBT that generates 500 W of heat. It is cooled with 20°C water at a 0.5 gpm flow rate. The surface of the cold plate must not exceed 55°C.
We know: Tin: 20°C, Tmax: 55°C, Q: 500 Watts, Area: 8 in2
We need to calculate Tout and θ.
First calculate Tout. Using the heat capacity graphs in our technical reference, we can see that the temperature change for 500W at a 0.5 gpm flow rate is 4°C. Therefore Tout = 20°C + 4°C = 24°C.
Tout is less than Tmax so we can proceed to the second part of the problem. The required thermal resistance is given by this equation:
We then plot this point on the normalized thermal resistance graph. Any technology below this point will meet the thermal requirement. CP15, CP20, and CP30 provide the necessary thermal resistance. But because the cooling fluid is water, you should only consider the CP15 cold plate.