Plastic filaments currently dominate the 3D printing field, since they melt at relatively low temperatures, form stackable disk-shaped structures, and bond together with ease. Although this material has many advantages and has even propelled a growing industry, technicians are eager for the next advancement in technology: the ability to print with highly conductive, and heat-resistant, metals.
The applications are virtually limitless. This process could yield benefits for the production of ultra-small processors, the design of smartphone cooling systems, and much, much more. And, recently, researchers from FOM and the Univeristy of Twente majorly improved upon previous studies pioneering this 3D printing technique, taking us one step closer to this reality.
It Has Been Difficult to Perfect this Process of 3D Printing:
Most metals have exceedingly high melting points, which require sophisticated printing nozzles for printers. The deposition process of metals compounds this difficulty. Previous experiments utilized low laser energies, which proved difficult when stacking metal droplets deposited from the nozzle onto a substrate.
According to the school’s publishing, “In this study, the researchers used a surprisingly high laser energy in comparison to earlier work, to increase the impact velocity of the metal droplets. When these fast droplets impact onto the substrate, they deform into a disk shape and solidify in that form. The disk shape is essential for a sturdy 3D print: it allows the researchers to firmly stack the droplets on top of each other.”
The Next Step Forward:
3D printed structures of this size, ranging anywhere from 100 nanometers to 10 micrometers, have proved difficult to manufacture. Researchers at the University of Twente have just pushed the envelope, by perfecting previously established methods of printing with copper and gold, and then publishing the means of duplicating their results here.
The process is highly technical, improving upon older methods for printing metal, but essentially boils down to this: a supercharged laser melts the material into micrometer-sized droplets, which are then manipulated into becoming the desirable disk-shape by a focused pulse laser. Finally, these easily-stackable, micrometer-sized disks of copper and gold are carefully arranged onto a substrate by the researchers.
Keep in mind that a micrometer is a millionth of a meter in size. In context, the average human hair is 75 micrometers wide. The overall success of this study lies not in the sophistication of the technology used to print the copper and gold, but rather in what the researchers were able to print with it. The journal entry asserts, “The researchers stacked thousands of drops to form micro-pillars with a height of 2 millimeters and a diameter of five micrometers. They also printed vertical electrodes in a cavity, as well as lines of copper.” This application very well may be the next step forward in many fields of study, such as electrical engineering or aerospace design.
Room for Improvement:
There remains one significant setback to the process outlined in this article. According to the findings of the University of Twente, “The high laser energy also results in droplets landing on the substrate next to the desired location. At present this cannot be prevented.” As this study improved upon established methods of peers in their field, there is room still for others to improve upon the University’s processes, to perfect the technology, and yield a cleaner final print free of excess debris.