At the heart of nearly every electronic device is a printed circuit board: typically a flat, green board covered with computer chips and other electronic circuit components. The world produces over 50 million metric tons of electronic waste a year, and hard-to-recycle PCBs make up a big part of that waste.
Now researchers from the Swiss Federal Laboratories for Material Science and Technology have found a way to make those green boards truly green, by making them biodegradable. The team incorporated the boards made from the wood-based material into a functioning computer mouse that is fully compostable, as detailed in the journal Scientific Reports.
PCBs are typically made of fiber-reinforced epoxy resin, a composite material in which glass fibers are embedded in a petroleum-based plastic. The composite is not easy or valuable enough to recycle, so it usually ends up in landfills or burned to separate the valuable metals on the board for reuse.
In attempts to make PCBs more sustainable, researchers have in the past made PCBs using the veinous structures of leaves and from biodegradable mushroom skin. Some have also tried to make PCBs using plastics that are easier to recycle.
The Swiss scientists made their PCB substrate using molecules that are natural building blocks of wood. Cellulose is a fibrous carbohydrate molecule found in plant cell walls. Lignin is a polymer that acts like a glue to hold other molecules together and impart strength and rigidity to woody biomass.
The team extracted tiny fibers made of lignocellulose from the lignin-rich cellulose pulp that is produced as a waste during biorefinery processes. The researchers add water to the fibers and grind the paste, which breaks down the relatively thick cellulose fibers into thinner fibrils. The result is a fine network of interconnected fibrils.
When the researchers squeeze the water out of the mixture under high pressure, the fibrils move closer and form a dense, solid mass. This gives a compostable board that shows mechanical properties, electrical properties, surface uniformity, and heat conductivity comparable to a conventional circuit board made of fiber-reinforced epoxy resin.
But the wood-based PCB is slightly less resistant to water and humidity. The researchers plan to improve that property next.
As a demonstration, the team inkjet printed electronic components on the lignocellulose PCB board to make the circuit that goes in a computer mouse. They 3D-printed the mouse case with an eco-friendly material made of wood and a bioplastic.
“This study underscores the potential of wood-derived nanomaterials to reduce electronic waste associated with conventional PCB materials and promote the development of a more eco-friendly electronics,” they write.
Source: Yuliiya Dudnyk et al. Printed circuit board substrates derived from lignocellulose nanofibrils for sustainable electronics applications. Scientific Reports, 2025.
Image: ©Anthropocene Magazine
