Multi-material 3D printing technology: integrated preparation of polymers and metals

Existing three-dimensional (3D) printing technologies, both polymer-based and metal-based, can only fabricate (only) plastic structures or (only) metal structures, which severely limits the application of additive manufacturing technologies in electronics such as IOT, ICT and robotics. Electronic devices are usually composed of both functional plastics and metals, including sensors and micro-actuators. They are connected together to manipulate the flow of electric current for the purpose of controlling information processing. With the proposed Plastic-metal Composite 3D Printing Technology, the above limitations can be broken through in a historic way. Our 3D printing technology enables the fabrication of both plastic and metal, allowing for the topology of metal designed on any complex functional plastic structure or even internal components. This can be in the form of 3D wires, patterns, topologies, or even large-scale structures with surface microstructures. Our technology is potentially important for both academic research and industry. Because it makes possible the integrated fabrication of 3D electronics, it will lead to smaller, lighter and smarter electronics with improved functionality and performance. This opens up a new world of applications of 3D printing technology in electronic technology.

Our manufacturing strategy is realized by the newly developed multi-material DLP3D printer and electroless plating process. Among them, the former enables multi-material composite fabrication with normal photosensitive ink and reactive photosensitive ink, while in the electroless plating process, the topology of the reactive ink interns the selective deposition of metals. Our strategy aims to construct a plastic/metal heterogeneous multimaterial interface and build it as a whole on or even inside any 3D functional substrate with arbitrary shape. The interface consists of our newly prepared reactive inks and a metal layer deposited after electroless plating, while the intermediate layer formed in the process is the nanotechnological basis for fusing the two into a single whole. The substitution of metal-based electrons by the heterogeneous multimaterial interface allows the metal to play the role of electron cycling during the information exchange process and the functional properties of the active ink itself.

Relying on this strategy, we have developed two generations of multimaterial DLP3D printers that enable the fabrication of plastic-metal composite structures with a minimum resolution of 20 um-40 um. Notably, this technology provides a process technology and thus enables the direct construction of 3D electronics with different functionalities. By assigning different functions to plastics and combining them with different kinds of metals (Ni, Cu, Au and other common metals are available), we can directly fabricate latticed electrode structures, complex and precise jewelry, sensors, robots, and even metamaterials electronic devices for a wide range of applications. Thus, the proposed technology has great potential for both academic research and industrial applications.