Sustainable direct metallization of 3D-printed metal-infused polymer parts: a novel green approach to direct copper electroless plating

Metallization, which is coating metals on the surface of objects, has opened up new possibilities for lightweight structures while integrating polymer and metal features. Electroless plating is a potential method for metalizing plastic 3D-printed parts; however, conventional approaches rely on pre-surface activation and catalyzation with expensive metal catalysts and hazardous acids. To address these issues, the current study represents a novel eco-friendly and low-cost approach for direct metallization of non-conductive 3D-printed parts, without using hazardous, toxic, and expensive conventional pre-treatments. Using the developed methodology, we electrolessly copper plated polymer-copper infused 3D-printed part as well as plastic components for the first time, directly. We initiated and implemented the idea of exposing the copper particles embedded in the polymer to the surface of copper-polymer parts by applying a sustainable mechanical or chemical method to make the surface conductive and ready for direct plating. A formaldehyde-free (green) electroless copper solution was developed in-house in addition to skipping conventional etching pre-treatment using harmful chemicals, making this a real step forward in the sustainable metallization of 3D-printed parts. In this study, the mechanical properties of copper-polylactic acid (PLA) 3D-printed parts revealed a 65% reduction in tensile strength and 63% increase in tensile modulus, compared to virgin PLA. Furthermore, the morphological characterization of the copper coated 3D-printed parts showed a homogeneous copper coating on the surface after direct electroless plating, with a plating rate of 7.5 μm/h. Allowing complex and functional devices printed in this manner to be quickly metalized without modification using toxic and costly solutions is a significant advancement in lowering the cost and manufacturing complexity of 3D-printed parts, increasing efficiencies, and lowering weight, and thus is a game changer in the technology’s adoption.