Modern printed circuit boards are made from petroleum-based materials and are difficult to recycle. In a leap toward eco-friendly electronics, researchers at Empa have developed fully biodegradable printed circuit boards crafted from wood-based composites and bio-resin binders. Unlike conventional petroleum-derived PCBs, which pose significant recycling challenges, this innovative biomaterial offers a sustainable alternative without compromising functionality.
The substrate generally used for PCB traces and components is a laminate made of fiber-reinforced epoxy resin. This composite material is based on petroleum and cannot be recycled. Researchers led by Thomas Geiger from Empa's Cellulose and Wood Materials laboratory developed a wood-based substrate for PCBs that can compete with conventional epoxy resin and is also completely biodegradable, as part of the EU research project HyPELignum.
Dream Team of Fibrils and Lignin
The source for the carrier material is a natural mixture of cellulose with a small amount of lignin. The flaky lignocellulose is ground by adding water to break down the relatively thick cellulose fibers into thinner fibrils, creating a fine network of interconnected fibrils. In a next step, the water is squeezed out under high pressure — the fibrils move closer together and dry to form a solid mass through a process called hornification. The lignin contained in the material serves as an additional binding agent.
A Compostable Computer Mouse
In collaboration with industrial partner PROFACTOR GmbH in Austria, the researchers have printed conductive traces on their sustainable circuit boards and fitted them with components to produce functioning electronic devices, such as a computer mouse or an RFID card. At the end of its service life, such a device could be composted — once the carrier material has decomposed, the metallic and electronic components can be removed from the compost and recycled.
The EU research project HyPELignum aims to develop a holistic approach to functional, CO2-neutral electronics, funded under the Horizon Europe program, running from October 2022 to September 2026.
Source: www.empa.ch
