Effect of micro fin geometry on natural convection heat transfer of horizontal microstructures

Micro-scale natural convection plays an important role in heat removal from microelectronic components and Micro-Electro-Mechanical Systems (MEMS) devices. Natural convection of macrofin arrays has been extensively studied by many researchers over the past several decades; however analysis of free convection around micro fin arrays is less well researched. The objective of this work was to experimentally investigate the effects of micro fin height and spacing on heat transfer coefficient for a horizontally mounted heat sink when operating under steady state natural convection conditions. An array of micro finned copper heat sinks was fabricated using micro-electro discharge wire machining (μ-EDWM) with fin height ranging from 0.25 to 1.0 mm and fin spacing from 0.5 to 1.0 mm respectively. Results showed that values of the convective heat transfer coefficient increased with increased fin spacing and decreased as fin height increased. Benchmarking tests were conducted on a flat plate heat sink with footprint similar to the micro finned structure. Additionally Computational Fluid Dynamic (CFD) modelling of laminar natural convection heat transfer was also carried out for a horizontal flat plate. It was found that the experimental results and those from the CFD modelling agreed with published correlations.