Case-embedded cooling for high heat flux microwave multi-chip array

This work proposes a case-embedded cooling (CECool) for microwave multi-chip module and theoretically studies its cooling capacity based on an improved analytical model. In this solution, the microfluidic cooling is integrated inside the case of the module to shorten the path of heat transfer. The model is used to calculate the thermal resistance from the chip to the coolant. The accuracy of the model is improved by setting the thermal diffusion angle to vary with the difference in thermal conductivities between the materials, which is validated by 3D finite-element-method simulation. Thermal performance of the remote cooling approach is studied first to help determine the application range of the CECool. By optimizing the materials and the microchannel, the thermal resistance of the CECool can be reduced to 5.7 degrees Cmm2/W. It is possible to increase the maximum tolerant heat flux to 1300 W/cm2 by enhancing the microfluidic cooling and choosing the chip type, meanwhile keeping the rise of junction temperature below 60 degrees C. A thermal test vehicle composed of 4 x 4 chip array is manufactured for demonstration. The accuracy of the model is verified by the experiment at 471 W/cm2. The maximum error is only 5.4%.