Detailed film coefficient measurement on a simple large-scale semiconductor package geometry

Detailed measurements of the surface film coefficient for a scaled-up package model are described. The importance of Reynolds number (Re) and Grashof number (Gr) for a correlation of Nusselt number is provided at the high end of the Reynolds number range applicable to the electronics cooling problem. The model surfaces are heated by driving a direct current through thin stainless steel strips that cover the surface. The temperature distribution on the underneath side of the strips is measured at approximately 180 locations by the use of resistive temperature sensors. The local heat transfer coefficient is obtained by performing an energy balance temperature sensor. An automatic data acquisition system is used for all temperature measurements. The results show the level of Gr/Re/sup 2/ at which buoyancy forces become important for modeling the electronics component heat transfer problem as well as the features of the Nusselt number distribution over the package and board surface.<>