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Waseda University develops novel 3D printing method for complex metal-plastic composite structures

Source:        DateTime:2022.12.27        Hits:

Researchers from Japan and Singapore have developed a new 3D printing process for the fabrication of 3D metal-plastic composite structures with complex shapes.

According to Waseda University, research interest in the 3D printing of metal patterns on plastic parts has grown exponentially in recent years.

3D metal-plastic composite structures have potential to be applied in areas such as smart electronics, micro-nanosensing, internet-of-things (IoT) devices, and quantum computing. Devices constructed using these structures have a higher degree of design freedom, and can have more complex structures, complex geometry and increasingly smaller sizes. Waseda says that current methods to fabricate such parts are expensive and complicated.

The process developed by the group of researchers from Japan and Singapore is a multi-material digital light processing 3D printing (MM-DLP3DP) process. 

Lead authors Professor Shinjiro Umezu, Mr. Kewei Song from Waseda University and Professor Hirokata Sato from Nanyang Technological University, Singapore said: “Robots and IoT devices are evolving at a lightning pace. Thus, the technology to manufacture them must evolve as well. Although existing technology can manufacture 3D circuits, stacking flat circuits is still an active area of research. We wanted to address this issue to create highly functional devices to promote the progress and development of human society.”

The MM-DLP3DP process begins with the preparation of active precursors, chemicals which can be converted into the desired chemical after 3D printing, as the desired chemical cannot be 3D printed itself. In this process, palladium ions are added to light-cured resins to prepare the active precursors.

The palladium ions are added to promote electroless plating (ELP), a process that describes the auto-catalytic reduction of metal ions in an aqueous solution to form a metal coating. The next step of the process is to fabricate the microstructures containing nested regions of the resin or the active precursor.

The materials are then directly plated, and 3D metal patterns are added using ELP.

According to Waseda University, the team manufactured a variety of parts with complex topologies to demonstrate the manufacturing capabilities of the proposed technique. The parts had complex structures with multi-material nesting layers, including microporous and tiny hollow structures. The smallest hollow structure was 40µm in size.

The metal patterns were ‘very specific’ and could be precisely controlled according to Waseda. The team also manufactured 3D circuit boards with complex metal topologies, including an LED stereo circuit with nickel and a double-sided 3D circuit with copper.

“Using the MM-DLP3DP process, arbitrarily complex metal-plastic 3D parts having specific metal patterns can be fabricated. Furthermore, selectively inducing metal deposition using active precursors can provide higher quality metal coatings. Together, these factors can contribute to the development of highly integrated and customisable 3D microelectronics,” said Umezu, Song, and Sato.

Waseda University says that the new manufacturing process promises to be a breakthrough technology for the manufacturing of circuits, with applications in a diverse variety of technologies. The university mentions 3D electronics, metamaterials, flexible wearing devices and metal hollow electrodes as some of the potential applications.

In November, a team of researchers at Waseda University proposed a design strategy to address the challenge of deformation caused by residual stress in metal additive manufacturing fabrication technology.