Перероблювальна друкована плата з вітрімеру/Alex Parrish for Virginia Tech
Scientists from the Virginia Institute of Technology in the United States have created new printed circuit boards with liquid metal, which are self-healing and work effectively even in severe damage.
These boards can also be recycled at the end of their service life. They were created from a new material called vitrimer, a special polymer that is able to remain rigid and strong at normal temperatures but is plastic and able to change shape at higher temperatures.
Typically printed circuit boards are made of materials such as silicone and epoxy resins — plastics that remain solid and rigid even when exposed to heat. However, the shape of the printhead can be changed by high temperatures. This makes it possible to develop completely new PCB configurations. In addition, windmill PCBs can be repaired in the event of damage. They are easier to disassemble and remove individual materials as needed.
«Our material is not like conventional electronic composites. Printed circuit boards are surprisingly durable and functional. Even if they are mechanically deformed or damaged, they continue to work», — emphasizes Professor of Mechanical Engineering at Virginia Tech Michael Bartlett.
To evaluate the new material, the researchers used a universal testing machine that stretches or compresses the material to measure its deformation during tearing. Adding just 5% by volume of liquid metal droplets to the wind tunnel roughly doubled the tensile strain compared to the wind tunnel alone.
To test the material impregnated with liquid metal, the group also used a device called a rheometer, which measures the fluidity and deformation behavior of materials.They applied a 1% strain at temperatures between 170 °C and 200 °C and found that the wind tunnel was able to soften and return to its original state, which is something that traditional thermoset materials cannot do.
The wind tunnel is combined with liquid metal droplets that replicate the function of the rigid metal wires in traditional PCBs, providing conductivity. The resulting material is so conductive that only 5% of the mixture needs to be liquid metal.
The developers assure that the new type of printed circuit board is able to continue to work efficiently even under high loads, in case of deformation and shape change under the influence of high temperatures. The new type of printed circuit board was created to reduce electronic waste.
Currently, electronics, including printed circuit boards, are thrown away due to damage or difficulties with material recycling. According to the UN, the volume of electronic waste has doubled over the past 12 years from 34 billion kg to 62 billion. Only a small percentage of discarded printed circuit boards, such as gold electrodes or some other precious minerals and metals, are recovered in the recycling process, which involves chemical treatment using strong acids.
«Traditional PCBs are made of permanent thermosetting materials that are incredibly difficult to recycle. Our dynamic composite material can be repaired or reshaped in the event of damage by applying heat, and its electrical performance will not be affected. Modern printed circuit boards simply cannot do this», — says one of the study’s co-authors, a professor of chemistry at Virginia Tech Josh Worch.
The results of the study were published in the journal Advanced Materials
Source: LiveScience
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