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Printed circuit boards (PCBs) are the unsung hero of electrical and electronic systems and they’re everywhere. In simplistic terms, a PCB provides the physical connectivity that pings power and data signals between many of the components in your devices, acting very much like the track between two train stations. The complex multi-layer construction of traditional PCBs means that they’re too complicated to recycle at scale, but a team at the University of Washington has developed a recyclable alternative, the vPCB.
vPCBs are vitrimer printed circuit boards. Vitrimers are a plastic polymer that can change viscosity at certain temperatures, shifting from solid to more malleable or liquid states. The University of Washington team has used a form of vitrimer that collapses into a jelly-like substance when it reacts to a specific solvent, allowing for easier retrieval of the vPCB’s components and currently impossible repurposing possibilities as the jelly can be reformed back into a vPCB.
With difficulty, which is why ‘we’ (though it’s probably not your fault) don’t really do it. The problem is that PCBs don’t naturally evaporate into pleasant scented mist when they reach the end of life, but are instead buried, crushed or incinerated into e-waste.
It’s estimated that although PCBs account for around 3-6% of global e-waste, their composition of plastics, flame retardants, persistent organic pollutants (POPs) and various heavy metals make them highly toxic. If they’re not handled properly during the recycling process (and in the main, they’re not) then debris, fumes and leaching deposits find their way back into our environment, causing air, soil and water pollution.
Not to labour the point, but an environment with polluted soil, unusable water and unbreathable air will not be great at sustaining life.
Another wasteful consequence of destroying PCBs is the loss of the highly valuable materials contained within. The main PCB inside the device you’re using at this moment may contain an expensive CPU, RAM, storage and a plethora of reusable components and recyclable metals such as gold, copper, aluminium and tin.
A circular economy model works by reclaiming these reusables for reuse, but modern PCBs make this (ironically) financially unviable. However, the vPCBs developed by the University of Washington could be the beginning of electronic circularity at scale.
The team stated that the vitrimer jelly can be re-used to make new vPCBs. Researchers were able to recover 98% of the vitrimer, 100% of the glass fibre (part of the structure of PCBs) and 91% of the solvent after recycling.
The chances of reusing valuable components from vPCBs are also much higher than with conventional PCBs. The low boiling point of the organic solvent used to turn the vPCBs into jelly means the components don’t have to undergo a potentially destructive heat cycle to remove them.
vPCBs are believed to have comparable strength and conductive properties to traditional PCB materials, but as vitrimers are a relatively recent development, the team are using AI to discover better formulations.
Let’s hope vPCBs do indeed become mainstream, though we should recognise that Dell has been trying to reformulate PCBs for some years. In 2021, Concept Luna mentioned developing PCBs to use flax fibre as source material with a water-soluble polymer as the bond. Dell hasn’t announced an update on this technology since so it’s impossible to say how successful they were.
However, the University of Washington’s vPCB research has been funded by various programs from Google, Microsoft and Amazon (so the department’s AI research bills should be cheap enough) and the team comprises engineers and scientists from Microsoft Research.
All three companies produce and use vast quantities of hardware that use traditional PCBs, so it will be fascinating to see if any of them take their funded research and make vPCBs a commercial reality.
