A recent UN report states that a staggering 137 billion pounds of e-waste will be generated globally in 2022, an 82% increase from 2010. However, less than a quarter of e-waste will be recycled in 2022. While there are many factors that prevent electronics from achieving sustainable recycling, one of the main barriers is our lack of a large-scale system to recycle the printed circuit boards (PCBs) that are contained in nearly all electronic devices.
PCBs are key components in electronic devices, responsible for housing and connecting other electronic components such as chips and transistors. They typically consist of multiple layers of thin glass fiber boards coated with hard plastics and laminated with copper. Because these plastic layers are difficult to separate from the glass fibers, PCBs often end up in landfills, where the chemicals they contain can potentially permeate the surrounding environment and potentially pollute it.
PCBs may also be incinerated to extract valuable metals from electronic devices, such as gold and copper. This incineration process, which is usually carried out in some developing countries, is not only inefficient but can also produce toxic substances - especially risky for workers who lack proper protection.
A team of researchers at the University of Washington has developed a new type of PCB that is comparable in performance to traditional materials and can be recycled over and over again with little material loss. The researchers used a special solvent that transforms an advanced sustainable polymer called vitreous into a jelly-like substance without damaging its structure, so that the solid component can be removed for reuse or recycling.
This vitreous jelly can be used over and over again to make new, high-quality PCBs, unlike traditional plastics, which degrade heavily during each recycling process. With these "vPCBs" (vitreous printed circuit boards), the researchers were able to recover 98% of the vitreous material, 100% of the glass fibers, and 91% of the solvents used in the recycling process.
The researchers found that the method of recycling these vitreous printed circuit boards (vPCBs) was to immerse the material in an organic solvent with a low boiling point. This process causes the plastic of the vPCBs to expand, but does not damage the glass substrate or electronic components, allowing the researchers to remove them for reuse.
This process opens up several possibilities for achieving a more sustainable and circular life cycle for PCBs. For example, damaged boards, such as those that are cracked or deformed, can be repaired in some cases. If they cannot be repaired, they can be separated from the electronic components. These electronic components can then be recycled or reused, while the vitreous and glass fibers can be recycled and made into new vPCBs.
The research team tested the vPCBs for strength and electrical properties and showed that their performance is comparable to that of the most commonly used PCB material today (FR-4). The researchers are now using artificial intelligence techniques to explore new vitreous formulations for different applications.
The team analyzed the environmental impact and found that recycled vPCBs can reduce global warming potential by 48% and reduce carcinogenic emissions by 81% compared to conventional PCBs.
While this work provides a technological solution, the team noted that a major hurdle to recycling vPCBs on a large scale will be the creation of systems and incentives to collect e-waste so that it can be recycled.
