Thermal design method of printed circuit board with effective thermal conductivity

Electrical component temperature on Printed Circuit Board (PCB) becomes higher due to high density packaging of electrical equipments, and heat conduction through the PCB is used as one of the cooling solutions. However, temperature prediction with detailed model of complex wirings of PCB in Computational Fluid Dynamics (CFD) is high calculation load. To reduce the calculation load, temperature prediction method with effective thermal conductivity is attractive. Accuracy of the method is influenced by applied effective thermal conductivities to the model. In this paper, we verify the accuracy of temperature prediction method with measured effective thermal conductivity in the case of commercial PCB. We measured in-plane and out-of-plane effective thermal conductivities and performed CFD analysis with the measured effective thermal conductivity. Then, we measured temperature on PCB and compared experimental and analytical results. The results of CFD analysis showed good agreement with experimental results. The maximum difference of temperature rise between experimental result and analysis results was less than 4 K. Consequently, it was indicated that, if appropriate effective thermal conductivities are applied to the CFD model, we can realize accurate temperature prediction of PCBs with reduction of calculation load.