Correlations highlighting effects of the PCB’s Copper ratio on the free convective heat transfer for a tilted QFN32 electronic package

• Effects of the Copper ratio of a Printed Circuit Board on convection is examined.
• The convective heat transfer coefficient is determined on the QFN32 device.
• The proposed correlations provide a better modeling of this electronic device.
• The study optimize the thermal design and temperature control of the active QFN32.

The main objective of this work is to examine the effects of the Copper ratio constituting the upper face of a tilted Printed Circuit Board (PCB) on the natural convective heat transfer concerning an electronic equipment containing a quad flat non-lead type (QFN32) package. Calculations are done by means of the finite volume method for several positions of electronic device on the PCB which is inclined with respect to the horizontal at an angle ranging from 0° (horizontal position) to 90° (vertical position) with a step of 15°. The power generated by the QFN32 varies between 0.1 and 0.8 W, and 10 Copper ratio varying between 0.26% and 39.45% are considered. These ranges correspond to the normal operating of the active electronic device for the intended applications. The study shows that the thermal behavior of the distinct areas of the active package is affected by the Copper ratio. Correlations are proposed, allowing determination of the average convective heat transfer coefficient on the different areas of the QFN32 device, according to the considered values of the Copper ratio, the PCB’s inclination angle and the generated power. They optimize its design while controlling its temperature during operation. The results of this survey provide a better modeling of this conventional arrangement widely used in electronic applications.