Analytical thermal resistance model for calculating mean die temperature of eccentric quad flat no-leads packaging on printed circuit board

Quad Flat No-leads (QFN) packaging is one of the most commonly used packaging types for microelectronic devices due to its outstanding thermal performance. However, it is difficult to analyze the thermal performance of QFN packaging because numerical simulations and experiments often require a large amount of time and resources. In this work, an analytical thermal resistance network model for calculating the mean die temperature of eccentric QFN packaging on the printed circuit board (PCB) is presented. Based on the heat dissipation path from the die to ambient, the thermal resistance network is established. The analytical solution of the mean die temperature of QFN packaging is obtained by the analytical expressions of each thermal resistance in the thermal resistance network. Simulations by commercial software ANSYS provide a reference for verification of the present model. The comparison of the results between simulation and analytical solution shows that the network model can calculate the mean die temperature of QFN packaging accurately over wide ranges of PCB’s thermal conductivity and heat transfer coefficient, and the maximum relative error is only 4.73%. The present model is fast and resource-saving to predict the mean die temperature of QFN packaging; moreover, it provides an optimization method for QFN packaging design to achieve good reliability.