Thermal state of electronic assemblies applied to smart building equipped with QFN64 device subjected to natural convection

Abstract

The performance and reliability of electronic components and assemblies strongly depend on their thermal state. The knowledge of the temperature distribution throughout the assembly is therefore an essential element to ensure their correct operation. This is the main objective of this work that examines the case of a conventional assembly equipped with a quad flat non-lead QFN64 subjected to free convection. This active electronic package is welded on a PCB which may be inclined by an angle varying between 0° and 90° (horizontal and vertical positions respectively) and generates during its operation a high power ranging from 0.1 to 1W. Thermoregulation of the assembly is ensured by natural convection, given its many well known advantages in this engineering field. Accurate relationships are proposed to determine the temperature on different areas of the device and the PCB. They are determined by means of a 3D numerical approach based on the finite volume method confirmed by measurements on an actual installation. These relationships allow reliability improvement of these electronic assemblies that are widely used in many engineering fields such as computing industry, mobile telephony, home automation, automotive, embarked electronics and the smart building applications considered in this work. The present survey complements a recent study which quantifies the natural convective heat transfer on the considered electronic assembly equipped with the QFN64 device, for the same power range and angle of inclination.