Detailed Correlations on Natural Convective Heat Transfer Coefficients for a QFN32 Electronic Device on Inclined PCB

Abstract : Correlations allowing the calculations of the convective heat transfer coefficient on all elements of an electronic assembly are proposed in this work. The active element is a Quad Flat Non-Lead-type QFN32 package that may be welded in any position of a printed circuit board (PCB) inclined with respect to the horizontal at an angle ranging from 0° (horizontal position) to 90° (vertical position) by steps of 15°. The power generated by the QFN32 varies between 0.1 W and 0.8 W, corresponding to its normal operating range. Six distinct surfaces are considered in this work and the power exchanged between each of them and the environment is quantified. This survey details a previous one in which it is quantified the global convective heat transfer concerning the whole assembly. The correlations proposed in the present work provide a better modeling of this conventional device widely used in electronic applications. They thus optimize its design while controlling its temperature during operation.