Selective Metallization of 3D Printable Thermoplastic Polyurethanes

This paper presents a selective metallization method for the newly developed 3D printable thermoplastic polyurethane elastomers (TPU): FilaFlex (R), SemiFlex (TM), PolyFlex (TM), and NinjaFlex (R). Silver nanoparticles were fabricated in-situ by photo-reduction on the surface of TPUs and acted as catalysts for copper ion adsorption. This method demonstrates the successful fabrication of copper patterns on flexible TPU filaments. Furthermore, Polyflex (TM) and acrylonitrile butadiene styrene (ABS) filaments printed in the same part have been used to enable selective electroless plating directly on Polyflex (TM) material. Electroless copper deposited onto Polyflex (TM) has a sheet resistance of (139.4 ± 7.2) m Ω/ and a copper conductivity of (1.1 ± 0.1) × 10⁷ S/m that is comparable with bulk copper. Copper-plated Polyflex (TM) interconnects were fabricated as a proof of concept demonstrators.