Evaluation of Additively Manufactured Microchannel Heat Sinks

Microchannel heat sinks allow the removal of dense heat loads from high-power electronic devices at modest chip temperature rises. Such heat sinks are produced primarily using conventional subtractive machining techniques or anisotropic chemical etching, which restricts the geometric features that can be produced. Owing to their layer-by-layer and direct-write approaches, additive manufacturing (AM) technologies enable more design-driven construction flexibility and offer improved geometric freedom. Various AM processes and materials are available, but their capability to produce features desirable for microchannel heat sinks has received a limited assessment. Following a survey of commercially mature AM techniques, direct metal laser sintering was used in this paper to produce both straight and manifold microchannel designs with hydraulic diameters of
$500~\mu \text{m}$
in an aluminum alloy (AlSi10Mg). Thermal and hydraulic performances were characterized over a range of mass fluxes from 500 to 2000 kg/m
²
s using water as the working fluid. The straight microchannel design allows these experimental results to be directly compared against widely accepted correlations from the literature. The manifold design demonstrates a more complex geometry that offers a reduced pressure drop. A comparison of the measured and predicted performance confirms that the nominal geometry is reproduced accurately enough to predict pressure drop based on conventional hydrodynamic theory, albeit with roughness-induced early transition to turbulence; however, the material properties are not known with sufficient accuracy to allow for
a priori
thermal design. New design guidelines are needed to exploit the benefits of AM while avoiding undesired or unanticipated performance impacts.