Laser 3D printing of complex copper structures

The ability to design complex copper (Cu) parts into the most efficient thermal structures is an old dream, but difficult to realize with conventional manufacturing techniques. The recent development of laser 3D printing techniques makes it possible to fully explore intricate designs and maximize the thermal performance of Cu-based thermal management components but present significant challenges due to its high optical reflectivity. In this study, we demonstrated the laser 3D printing of pure Cu with a moderate laser power (400 W). Dense Cu parts (95 %) with smooth surface finishing (R_a ∼18 μm) were obtained at a scan speed of 400 mm/s, a hatch distance of 0.12 mm, and a layer thickness of 0.03 mm. The hardness, electrical, and thermal conductivity of the printed Cu parts are 108 MPa, 5.71 × 10⁷ S/m, and 368 W/m·K, respectively which are close to those of bulk Cu. Additionally, complex heat sink structures were printed with large surface areas (600 mm²/g), and their cooling performances were compared to a commercial heat sink with a smaller surface area (286 mm²/g) on an electronic chip. The complex heat sinks printed cools the electronic chip 45 % more efficiently than the commercial one. The introduction of selective laser melting to additively manufacturing Cu heat sinks offers the promise to enhance the performance beyond the scope of exciting thermal management components.