Circuit boards produced using renewable materials

International scientists have been working on different ways of utilising cellulose fibrils – fine fibres that can be produced from wood pulp or agricultural waste – to produce sustainable electronics.

Cellulose fibrils hold great potential for sustainable production and the decarbonisation of industry, as they grow CO2-neutral in nature, burn without residues and are compostable. 

Researcher Thomas Geiger, from the Swiss Federal Laboratories for Materials Science and Technology (Empa), has demonstrated it is possible to build biodegradable circuit boards from cellulose fibrils. 

Together with a colleague, he produced 20 experimental boards, which were subjected to various mechanical tests and finally fitted with electronic components. The test succeeded, and the cellulose board released the soldered-on components after a few weeks in natural soil.

Geiger continued his research on a new sustainable electronics project alongside sustainability specialist Claudia Som. The project, named Hypelignum, is led by the Swedish materials research institute RISE and began in October 2022. 

In collaboration with researchers from Austria, Slovenia, Spain, the Netherlands, Sweden and Switzerland, the team is now working on producing eco-circuit boards made of various materials.

In addition to nanofibrillated cellulose (CNF), wood wool and wood pulp are being investigated as a base. Moreover, wood veneer is also being used as a base for the circuit boards.

The two Empa labs work in tandem. While Som’s team uses material databases to calculate the ecological footprint of the eco circuit boards, Geiger’s will manufacture the circuit boards from renewable raw materials.

Their goal is to industrially produce computer circuit boards, that have high mechanical strength, while also not swelling in humid conditions or forming cracks at very low humidity.

“Cellulose fibres can be a very good alternative to glass fibre composites,” Geiger explained. “We dewater the material in a special press with 150 tons of pressure. Then the cellulose fibrils stick together on their own without any additives. We call this ‘hornification’.”

The EU Hypelignum project also aims to develop conductive inks for the electrical connections between individual components. These inks are often made based on silver nanoparticles. The researchers are looking for cheaper and less scarce substitute materials, as well as an ecological production method for these nanoparticles.

When the project is finalised, the researchers are aiming to present four achievements: an ecologically exemplary printed circuit board; a large construction element made of wood that will be equipped with sensors and actuators; pieces of furniture that will be equipped with sensors in an automated production line, and a demonstrator that will prove the recyclability of all these components.