A printed circuit board (PCB) made of materials that can be repeatedly recycled could help alleviate the world’s growing electronic-waste problem. The recyclable PCBs, described in a paper published 26 April in the journal Nature Sustainability, perform as well as conventional boards, but unlike conventional PCBs they can be readily repaired. Additionally, the materials used to make recyclable PCBs can be recovered and reused.
According to the United Nations, the world produced 62 billion tons of electronic waste in 2022, and we’re on track to produce 82 billion tonnes in 2030—an increase of over 30 percent. Chemicals can leach out of electronic waste and pollute water supplies; when e-waste is burned to recover valuable materials like gold and copper, it produces air pollution.
Conventional PCBs, which are the substrates that hold computer chips and their interconnections, are at the heart of this environmental problem. They are made up of glass fibers mixed with a type of plastic called a thermoset. These polymers look like a pile of cooked spaghetti. When they’re heated in the process of strengthening the board, all the points where the polymers cross one another become chemically bonded. Those chemical bonds are not reversible, and so conventional PCBs are not recyclable. They also can’t be readily repaired when they crack.