Laser Powder Bed Fusion of Copper-Tungsten Composites for Heat Sink Applications in High-Power Electronics

The use of metal matrix composites (MMCs) in laser powder bed fusion (PBF-LB/M) represents a promising yet underexplored field in additive manufacturing. MMCs offer tailored properties for specific applications, while PBF-LB/M enables the fabrication of complex geometries. In this article, a copper-tungsten (Cu/W) composite with 20 vol% W is qualified for the PBF-LB/M process, targeting heat sinks in high-power electronics. The objective is to reduce thermal stress in multilayer assemblies by lowering the coefficient of thermal expansion (CTE) while maintaining high thermal conductivity. To achieve this, process parameters are optimized to obtain dense parts, with relative densities reaching 99.4%. According to laser flash analysis, the thermal conductivity reaches 300.1 W/(m K) at 22°C, corresponding to 76.1% of pure Cu. The lowest measured CTE is 13.3 × 10-6 K-1 (20-300°C), reflecting a 23.1% reduction compared to Cu. Specific heat capacity, electrical conductivity, and hardness are also characterized. The influence of W content, its distribution in the Cu matrix, and porosity are analyzed. Physical models (Maxwell, Turner) are applied to predict material behavior. Finally, additively manufactured demonstrator components confirm the Cu/W composite's suitability for PBF-LB/M and demonstrate its potential for fabricating complex heat sink geometries.