Laser Powder Bed Fusion of Multi-Material Heat Sink on Silicon Substrate: A Sn-Al Solution for High-Power Electronic Heat Dissipation

Efficient thermal management is critical in modern high-power electronics, particularly for aerospace applications where compactness and reliability are essential. This work presents a multi-material thermal solution fabricated via Laser Powder Bed Fusion (PBF-LB/M), consisting of a SnAg3 thermal interface material and high-aspect-ratio AlSi10Mg pillar heat sinks directly printed on silicon wafers. Process parameters were optimized to ensure strong metallurgical anchoring while avoiding thermal damage to the brittle substrate. The SnAg3 layer exhibited a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex>-Sn matrix with finely distributed <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{A g}_{3} \text{S n}$</tex> intermetallics and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{S i}$</tex> inclusions resulting from controlled substrate remelting. AlSi10Mg pillars with 0.5 mm diameter reached up to 99.4% relative density, showing a fine cellular-dendritic microstructure and no delamination at the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Sn}-\text{Al}$</tex> interface. Moreover, thermal cycling from −70° C to +130° C confirmed interface stability. This approach demonstrates the feasibility of directly integrating TIM and heat sinks on silicon, paving the way for compact, additively manufactured thermal architectures in advanced electronics.