A Sustainable Approach to Plastronics: Dip-Coating-Assisted Area-Selective Metallization of 3D-Printed Polymer Substrates

Area-selective metallization of polymeric substrates has recently emerged as a promising approach for developing low-cost plastic-based electronics (plastronics). In this context, 3D printing, with its capability to fabricate intricate geometries and tailored designs, has become increasingly relevant for creating custom conductive circuitry. However, most existing metallization strategies for 3D-printed polymers rely on expensive instrumentation, strictly controlled environments, and aggressive chemical pretreatments, thereby limiting their scalability and environmental viability. This study presents a facile methodology that integrates material extrusion (MEX) with a dip coating of extruded circuitry pathways, using ABS as the model substrate. ABS, one of the oldest and most widely used thermoplastics in both conventional processing and MEX, was employed to fabricate substrates with well-defined circuitry features. The extruded circuitry regions were selectively dip-coated with micrometer-scale Cu particles, achieving an average resistivity of 2.081 × 10 –3 Ω·cm. These precoated pathways facilitated area-selective nucleation during subsequent electroless plating (ELP), enabling the formation of conductive metallic films without the need for harsh chemical etching or dedicated area-selective pretreatments. The methodology demonstrated resolution down to 200 μm in circuitry pathways, ensuring dimensional precision suitable for integrated plastronic applications. The dip-coated layer showed strong adhesion to the ABS substrate, while the subsequent Ni–P adhered robustly to the underlying Cu layer, forming a stable bilayer metallization system. The ability to achieve suitable electrical performance, strong coating adhesion, and environmental stability, while completely eliminating harsh pretreatment, highlights the environmental and economic advantages of this approach.