Additive Manufacturing of An Sn-Based Alloy on Silicon Wafer by Laser Powder Bed Fusion for Advanced Cooling of Electronic Circuits

The constant growth of interest in miniaturization of power sources for electronic circuitries necessitates utilizing high-performance cooling to fulfil their thermal management requirements. Unlike conventional cooling methods that rely on heat sinks mounted on conventional thermal interface materials (TIM), which create thermal resistance and reduce heat extraction efficiency at their interfaces, we are, hereby, proposing an additive manufacturing approach using Laser Powder Bed Fusion (LPBF) to realize wafer-scale printing of an Sn-based interlayer material on which a heat sink can be fabricated. The alloy's low melting point (~250 °C) mitigates thermal stresses during solidification and cooling that occur in the LPBF process. The thermal conductivity of this Sn-based alloy, estimated at 39.4 ± 6.7 W/mK, surpasses those of common thermal interface materials (1-10 W/mK), making it a competitive option for heat management applications. Microstructural analysis of the printed layers on Si wafer confirms the alloy’s uniformity and compatibility with silicon, proposing its effectiveness as a thermal interface material for cooling applications. By optimizing the volumetric energy density exerted during the LPBF print process, we could realize structures that are fully dense and free of cracks. The successful formation of the Sn-based alloy on Si wafer by LPBF is a stepstone for the realization of wafer-scale full additive manufacturing of heat sinks onto it.