Getting Fired Up About PCBs

Electronics may be inexpensive enough to be disposable these days, as evidenced by all of the vapes tossed in parking lots and by the side of the road, but that does not necessarily mean they should be tossed in the trash. Pretty much every component in a modern electronic device, from the microchips all the way down to the circuit board itself, leeches toxic chemicals into the environment as it starts to break down.

The more we toss, the worse the problem. So hardware hackers Patrícia J. Reis and Stefanie Wuschitz zeroed in on the most commonly found component of all — the printed circuit board (PCB). Typically made of FR-4, PCBs are loaded with epoxies and flame retardants that release toxic chemicals when they are destroyed. So Reis and Wuschitz came up with a clever — if not entirely practical — way to replace FR-4 with a more environmentally-friendly option.

Initially the team looked into ceramics, and especially porcelain, as alternatives to FR-4. While porcelain is generally considered to be environmentally friendly, it requires high firing temperatures in an electric kiln. So to minimize the energy that goes into the finished product, they kept looking for another material.

Their search ultimately led them to natural clay. With the right know-how, clay can be collected, cleaned, and prepared with minimal energy inputs. After brushing up on some prehistoric techniques, Reis and Wuschitz shaped the clay into hexagonal tiles about 10 cm across, flattened them with wooden slats and a rolling pin, and then imprinted them with 3D-printed stamps that marked out the circuit traces.

Drying the clay is a delicate process. Too fast, and cracks form; too slow, and moisture lingers in the center. But once the right formula was worked out, the boards were sanded smooth and painted with conductive silver paint made from recycled jewelry industry waste. Gold luster was also tested, but silver proved more conductive and, importantly, more solderable after firing.

The firing itself was done backyard-style, in pits dug into the earth and fueled by dry wood sticks. Carefully stacked like kindling, the clay boards were heated to about 700 °C. If all went well, the pieces glowed red in the fire, survived a dunk in cold water, and emerged as hardened, usable PCBs. These PCBs were then populated with ATmega328P microcontrollers of Arduino Uno fame to get some LEDs blinking.

The PCBs are eco-friendly, but they are also finicky to make, fragile, and labor-intensive, so it is safe to say that they will not replace FR-4 any time soon. But even if clay boards never scale up, the project is still a great example of how local, sustainable, and low-energy approaches might reshape the way we think about hardware in the future.

Everything from the instructions to the 3D models is open source and available on GitHub. Go grab it all if you feel like a day of playing in the mud.