The biodegradable mouse works like any other computer mouse – the 3D-printed casing was made from a mixture of biodegradable plastic and wood fibers. Photo: Empa

Swiss researchers have developed a biodegradable version of printed circuit boards—an important step toward sustainable electronics.

Printed circuit boards are the heart of every electronic device: they are covered with copper tracks and soldered electronic components, usually painted in a characteristic green color, and are made from fossil raw materials. The Swiss Federal Laboratories for Materials Science and Technology (Empa) is working on a sustainable variant—but the “green” alternative is actually brown and based on wood.

WASTE PRODUCT
The raw material for the substrate is a natural mixture of cellulose with some lignin, strictly speaking a waste product for which there has been no use to date. In order for the flaky lignocellulose to be turned into a high-tech product such as a printed circuit board, it must first be ground with the addition of water to break down the relatively thick cellulose fibers into fine cellulose fibrils. This creates a fine network of wafer-thin fibrils that are interconnected. In the next step, the water is pressed out of the mass under high pressure, the fibrils move closer together and dry to form a solid mass.

SENSITIVE TO MOISTURE
The resulting board is almost as resistant as a conventional printed circuit board made of glass fibers and epoxy. Almost – because the compostable board is still sensitive to water and high humidity, according to Empa. However, water is necessary to ensure biodegradability. The researchers are confident that the resistance of the lignocellulose biocomposite can be further improved with the right processing.

COMPOSTABLE COMPUTER MOUSE
The sustainable circuit boards are printed with conductor tracks and fitted 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 under the right conditions – once the carrier material has decomposed, the metallic and electronic components can be removed from the compost and recycled, according to Empa. Work is now underway to make the biomaterial for circuit boards more resistant without compromising its biodegradability. Further demonstration devices with lignocellulose boards are also planned.

Source: holzmagazin.com