Emily Velasco's Blinky Lights Build Needs No Printed Circuit Board: It's Pottery-Tronics

Self-described "arts-and-crafts supervillain" Emily Velasco has eschewed the traditional printed circuit board in favor of a "thrown" circuit board — building a ceramic astable multivibrator from clay and glaze.

"I've been doing ceramics for a couple years now," Velasco explains, "and recently people kept tagging me in posts about a European feminist hacker collective that was making circuit boards out of [clay] they dug out of the ground and fired in a campfire. After having an epiphany about some experimental copper ceramics glazes I made last year, I thought I would see if i could solder to them, and I found that I could."

Traditionally, circuit boards use fiberglass as a substrate — though there are flexible boards that use plastic polymers, while some manufacturers have even built commercial product outs of circuits printed on a glass substrate. Ceramics have traditionally been used to package silicon integrated circuit dice, but their weight and relative fragility means they've not been investigated as a circuit board substrate until now.

"I made a stamp and stamped out some really basic boards for an astable multivibrator (two blinky lights) circuit," Velasco explains of the experimental project. "I filled the recessed traces with copper powder and had them fired in our pottery kiln. Now I have ceramic circuit boards. It looks terrible, but it works."

The secret lies in the glaze. Like in a traditional PCB, the substrate is an insulator; the electrical impulses travel through conductive copper traces. Where a PCB is typically made by coating the substrate in a layer of copper then etching the copper away around a printed resist to leave traces behind, though, in Velasco's circuit the traces are made from channels filled with a thick layer of a copper-based glaze.

As the glaze is fired, it forms a conductive channel good enough for a circuit to be built. "I just mixed copper powder into some of the basic glazes we have at the studio," the maker explains, "like clear and green celadon. There are actually copper glazes that people use in raku firing though."

Soldering to the traces proved a bit of a challenge. "I had to fuss with it a bit," Velasco admits, "and there were some areas that wouldn't take the solder. At first it wouldn't take the solder at all, even with plumbing flux, and I had to go over it with the tiny wire wheel that comes with a Dremel [rotary multitool.]"

More information is available in Velasco's Mastodon thread.