Effect of Thermal via Design on Heat Dissipation of High-Lead QFN Packages Mounted on PCB

The quad flat no-lead package (QFN) is widely used in integrated circuits due to its
advantages in performance and cost. With the increasing power of electronic products, effective
heat dissipation from QFN packages has become crucial to prevent product damage. The focus of
this study is to investigate the thermal performance of QFN packages soldered onto printed circuit
boards (PCB) by finite element analysis (FEA). Conventional QFN, dual-row QFN, and high-lead
QFN packages were modeled and compared by ANSYSY software. The effect of thermal via design
(the distance, number, distribution, diameter, and thickness of thermal vias) on the QFN package
was investigated. The study revealed that the high-lead QFN package consistently demonstrated
superior heat dissipation performance than the other two under different conditions. Placing thermal
vias closer to the heat source enhances heat dissipation efficiency. Thermal vias positioned beneath
the thermal pad were particularly effective. Increasing thermal via quantity and diameter improved
heat dissipation, with square distribution layouts showing advantages. However, excessive copper
plating thickness can increase thermal resistance and hinder heat dissipation.