Special Filament, Electroless Plating Lets Dual-Extrusion Printers Print in Plastic and Metal

Researchers at Nanyang Technological University, Waseda University, and Yoshino Denka Kogyo Inc. have unveiled a new approach to combining metal and plastic in 3D printing objects — which, they claim, is environmentally-friendly and easily added to standard fused-filament fabrication printers.

"The metallization of local areas of 3D-printed plastic structures has attracted a significant amount of attention," the research team explains in the paper's abstract. "However, metal and plastic additive manufacturing technologies are incompatible with each other due to the significant difference in their associated process temperatures."

"Even though 3D printers let us create 3D structures from metal and plastic, most of the objects we see around us are a combination of both, including electronic devices," adds project lead Profession Shinjiro Umezu. "Thus, we thought we’d be able to expand the applications of conventional 3D printers if we managed to use them to create 3D objects made of both metal and plastic.”

"This paper proposes and demonstrates a plastic 3D printing technology that adopts electroless plating, a form of chemical metal deposition. The technology is capable of metalizing selected areas of 3D-printed plastic structures made of acrylonitrile butadiene styrene (ABS). Because electroless plating is triggered by a palladium (Pd) catalyst, this study designed and custom-fabricated an ABS filament that contains palladium chloride (PdCl2) as a catalyst precursor, which can be used in a fused filament fabrication (FFF) 3D printer."

The system works by using two filament types in an otherwise-unmodified Ultimaker 3 dual-extrusion FFF printer: One nozzle prints ABS plastic as normal; the other prints the ABS and Pd mixture. When the print is complete, it is run through an environmentally-friendly electroless plating system which coats the Pd areas with a uniform coating of nickel — skipping the usual chemical deposition step, which the researchers believe leads to poor adhesion, patchy metallic coating, and can only be applied to an entire object at once.

"Our hybrid 3D printing method has opened up the possibility of fabricating 3D electronics," Umezu notes, "so that devices and robots used in healthcare and nursing care could become significantly better than what we have today.”

The team's work has been published under open-access terms in the journal Additive Manufacturing.