Microfabrication of short pin fins on heat sink surfaces to augment heat transfer performance

Plate-fin heat sinks have been a successful technology in electronics cooling. Thermal performance of such heat sinks, however, has been driven to improve due to increasing heat generation in modern electronics devices. This paper proposes to introduce short pin fins on surfaces of plate-fin heat sinks to address such challenges. A microfabrication approach based on photolithography and electroplating technologies is devised to fabricate short copper pin fins on copper plates. The photolithography implements desired patterns of pin fins, and the electroplating enables pin fins to directly grow out of the base plate. A series of pin-fin coupons were fabricated using the devised method. A heat transfer test was designed to evaluate heat transfer augmentation by the pin fins. Fabricated coupons were tested in a rectangular channel and their thermal conductance and channel pressure drop were measured. A Design of Experiments (DoE) procedure via the Taguchi method was employed to find the influence of four factors: pin-fin height, diameter, spacing, and cross sectional shape, on the combination of thermal conductance and channel pressure drop for the coupons of different pin-fin parameters. Compared with similar plain coupons, pin-fin coupons of the best design parameters increase the thermal conductance by 78.3 % with only 7.8% increase of channel pressure drop. The devised micro-pin-fin fabrication has been proved as an effective approach to augmenting heat transfer of air-cooled plate-fin heat sinks.