Selective Surface Metallization of 3D-Printed Polymers by Cold-Spray-Assisted Electroless Deposition

Selective surface metallization of insulating polymers is of particular interest in smart films, energy harvesting, and sensing applications. However, traditional polymer metallization techniques face challenges due to the need for environmentally hazardous pretreatment (e.g., strong acid etching) and cost-intensive palladium seeding processes, thereby limiting the large-scale deployment of metallized polymers. With the advent of rapid prototyping, metallization on additively manufactured polymers drew attention in a variety of technological applications, as it enables the fabrication of low-cost electronic devices. In the current work, we deploy and evaluate a hybrid additive metallization route that can enable the fabrication of functional selective metallization on 3D-printed polymers in a rapid and eco-friendly methodology with improved electrical conductivity. The metallization route sequentially comprises (1) material extrusion 3D printing, (2) cold spray metallization, and (3) electroless deposition. The resulting metal (copper) layers on the polymer surfaces are characterized in terms of the microstructure, surface chemistry, wettability, and electrical conductivity. Notably, selective metallization with promising electrical conductivity (i.e., 6.47 × 10 6 S m –1 for ABS and 5.27 × 10 6 S m –1 for PLA parts) is achieved on both linear and curvilinear polymer surfaces. Moreover, strong adhesion between the metallized layer and the 3D-printed structures was confirmed by adhesion tests. Detailed evaluation of the proposed hybrid metallization route unlocks great potential to advance the field of conductive surface metallization on 3D-printed polymers.