Today’s printed circuit boards (PCBs) are made from fossil-based raw materials and are difficult to recycle. Researchers at Empa have developed a biodegradable alternative, marking an important step toward sustainable electronics. Their biomaterial is made entirely from wood and can be used to manufacture functional circuit boards for electronic devices.
A Sustainable Alternative to Conventional Circuit Boards
Printed circuit boards are the ”heart” of virtually every electronic device, from laptops to electric toothbrushes. These rigid boards contain copper circuits and soldered electronic components and are typically recognizable by their characteristic green color.
However, conventional PCBs are not environmentally friendly. The substrate that supports the copper circuitry is usually made from a glass fiber-reinforced epoxy resin laminate. This composite material is petroleum-based and cannot be recycled. Proper disposal is costly and often requires specialized pyrolysis furnaces with air-cleaning systems. Given the vast number of circuit boards discarded every year, this represents a significant environmental challenge.
Turning Wood Waste into Electronics
Thomas Geiger and his colleagues at Empa’s Cellulose and Wood Materials Laboratory have developed a sustainable alternative as part of the EU-funded HyPELignum research project.
Their circuit board substrate is made from lignocellulose, a natural material consisting primarily of cellulose and lignin derived from wood. In fact, the material was originally considered a waste product.
According to Geiger, project partners at the Dutch research institute TNO developed a process to extract lignin and hemicellulose from wood. What remains is a brownish lignocellulosic material for which there had previously been no practical application. Geiger, who has worked on cellulose-based electronics for many years, recognized its potential.
From Wood Fibers to High-Tech Components
To transform lignocellulose into a suitable material for electronics, researchers first grind it with water. This process breaks the relatively thick cellulose fibers into extremely fine cellulose fibrils, forming a dense interconnected network.
The material then undergoes a high-pressure dewatering process. As water is removed, the fibrils move closer together and dry into a solid mass. Researchers call this process cornification.
Nearly as Strong as Conventional PCBs
The resulting board is almost as durable as traditional fiberglass and epoxy-based circuit boards. However, it remains somewhat sensitive to water and high humidity.
A Compostable Computer Mouse
To demonstrate the technology, researchers produced fully functional computer mice using the new circuit boards. The mouse housing itself was manufactured using 3D printing and a biodegradable plastic blended with wood fibers.
Working together with Austrian industrial partner PROFACTOR GmbH, the team printed conductive circuits onto the sustainable boards and equipped them with electronic components to create devices such as computer mice and RFID cards.
At the end of their useful life, these devices could potentially be composted under appropriate conditions. Once the biodegradable substrate has decomposed, the metallic and electronic components can be recovered from the compost and recycled separately.
Rethinking Electronics
The researchers believe the durability of the lignocellulosic material can be improved further without compromising biodegradability.
Geiger argues that society may also need to reconsider how it designs electronics:
Many electronic products are used for only a few years before becoming obsolete. It may therefore not make sense to manufacture them from materials capable of lasting hundreds of years.
Contact Information
Dr. Thomas Geiger
Cellulose & Wood Materials, Empa
Phone: +41 58 765 47 23
Email: thomas.geiger@empa.ch