Liquid metal used in novel circuit board scan self-heal and work after taking heavy damage
A new type of self-healing and reconfigurable circuit board can withstand heavy damage and still work effectively, scientists say. It can even be completely recycled once it reaches the end of its life.
The new breakthrough is owed to a material called a vitrimer, a special polymer capable of remaining rigid and durable at normal temperatures but malleable and reshapable at higher temperatures. The scientists outlined their findings in a new study published 1 June in the journal Advanced Materials.
Circuit boards are traditionally built with thermosets, such as silicone or epoxy resins, a type of plastic that becomes permanently rigid and hard after being heat cured. But vitrimer can be altered by reapplying heat, meaning that the circuit boards can be adapted into entirely new configurations.
Using vitrimer also allows circuit boards to be repaired if damaged, while making them easy to break down and reclaim materials from.
“Our material is unlike conventional electronic composites,” said Michael Bartlett, an associate professor of mechanical engineering at Virginia Tech who co-led the study, in a statement. “The circuit boards are remarkably resilient and functional. Even under mechanical deformation or damage, they still work.”
Researchers used a universal testing machine, a machine that pulls or compresses a material to measure its strain at break (how much a material stretches before it breaks), to evaluate the new material.
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Adding just 5% by volume of liquid metal droplets to the vitrimer approximately doubled the strain at break versus vitrimer alone.
The team also used a device called a rheometer, which measures the flow and deformation behavior of materials, to test the liquid metal-infused material.
They applied 1% deformation at temperatures between 170 °C and 200 °C and found that the vitrimer was able to “relax” back to its original state, something traditional thermosets are incapable of doing.
‘Modern circuit boards simple cannot do this’
The vitrimer is blended with droplets of liquid metal, which replicate the function of rigid metal wires in traditional circuit boards, enabling conductivity. The resultant material is so conductive that only 5% of the blend needs to be liquid metal, the scientists said.
It combines the best qualities of traditional thermosets, which are mechanically strong and chemically resistant, with the reconfigurability and recyclability of thermoplastics.
The new type of circuit board can remain fully operational despite significant stress, deformation and “thermally triggered shape-memory transformations,” the scientists said.
The scientists designed the new circuit board to combat the rise of electronic waste. Presently, electronics, including circuit boards, are discarded due to damage or difficulty in reclaiming materials.
Electronic waste has doubled in the past 12 years, according to a 2024 report from the United Nations, from 34 billion kilograms to 62 billion kg.
Currently, only a small percentage of discarded circuit boards, like gold electrodes or select other precious minerals and metals, are recovered during the recycling process, which involves chemical treatment involving strong acids.
Because the base material of most boards is high-performance composites featuring non-recyclable thermosetting plastics, such as epoxy-laminated fiberglass sheets, the majority of the discarded material ends up in landfills.
“Traditional circuit boards are made from permanent thermosets that are incredibly difficult to recycle,” Josh Worch, an assistant professor of chemistry at Virginia Tech and co-lead author of the study, said in a statement.
“Here, our dynamic composite material can be healed or reshaped if damaged by applying heat, and the electrical performance will not suffer. Modern circuit boards simply cannot do this.”
While the team acknowledged that further work is necessary to allow recovery of a higher percentage of some of the materials, they said their work represented an important step forward in creating a circular economy for core electronic materials in everyday devices from cellphones and laptops to wearables and televisions.
