Microchannel heat sinks allow 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 limited assessment. Following a survey of commercially mature AM techniques, direct metal laser sintering (DMLS) was used in this work to produce both straight and manifold microchannel designs with hydraulic diameters of 500 μm in an aluminum alloy (AlSi10Mg). Thermal and hydraulic performance were characterized over a range of mass fluxes from 500 kg/m2s to 2000 kg/m2s 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 additive manufacturing while avoiding undesired or unanticipated performance impacts.
dditive manufacturing, direct metal laser sintering, microchannel heat sink, microchannel heat exchanger, power electronics
Date of this Version
I. L. Collins, J. A. Weibel, L. Pan, and S. V. Garimella, Evaluation of additively manufactured microchannel heat sinks, IEEE Transactions on Components Packaging and Manufacturing Technology 9, pp. 446-457, 2019.