Quick SPICE-Based Heat Transfer Estimator for QFN Packages on Multilayer PCB

The thermal design of Printed Circuit Boards (PCBs) is paramount for compact sensing applications featuring power-hungry on-board computing devices and to enhance devices lifespan. Traditionally, PCB thermal analysis use complex software tools with fluid dynamics or finite element (FEM) solvers, however, they are time-consuming. It limits rapid prototyping. This paper addresses this issue by introducing an automated tool for quick simulation of heat transfer in PCBs, focusing on cases involving quad-flat no-lead (QFN) packages. The tool aims to reduce simulation time and facilitate the design process for faster prototyping. The tool proposed in this study translates the thermal behavior of the PCB into an equivalent resistive network, which adjusts to the composition of the metal, dielectric, and solder mask in the analyzed regions. It incorporates image processing algorithms to identify thermal connections and reconstruct multi-layer structures, even with irregularly shaped metal areas. Simulation tests on a PCB sample demonstrated that the proposed tool provides results comparable (<2 ℃ within an area that can achieve up to 24.6 cm2 from QFN) with a professional FEM thermal analysis software but 91.16x faster.