Angelo Casimiro Demonstrates How Baby Oil Can Offer an Easy Route to High-Quality PCB Production

Student Angelo Casimiro has shared a method for easily producing single-sided printed circuit boards (PCBs) from inkjet-printed transfers, without the need for any special paper — and the secret is baby oil.

"Toner transfer method has been the number one go-to in homebrew PCB fabrication, next to the Sharpie method," Casimiro explains, referring to a technique in which a PCB layout is printed on a laser printer then transferred onto a blank PCB using a hot iron or laminator. "Toner transfer has its own limitations. One, is that you would need a toner printer, common inkjet printers simply wouldn't work. Second, as your line traces gets thinner, it would be more difficult to transfer the toner prints to the copper clad.

"Pre-sensitised PCBs on the other hand creates the sharpest lines of all the homebrew fabrication methods. This is perfect for smaller circuits that involves SMT (Surface Mount) components. I use this method for building PCBs with line traces reaching down to 10mils (0.254mm)."

To avoid the need for a laser printer, Casimiro opts for an interested means of putting the PCB design onto the pre-sensitised blank ready for etching. "Most people would use acetate or parchment paper for printing the PCB layout. Those types of paper are ideal for photo exposure since it allows more light to pass through," he notes. "The disadvantage though, is that it's difficult to print on these types of papers using inkjet printers, since they blot more often.

"Adding baby oil to your plain paper PCB layout would allow more light to pass through during the photo exposure process. It turns and plain paper into parchment paper."

The process is simple: Coating the PCB in baby oil, pressing the design face-down onto the now-oily PCB, then putting the result onto a bright light — CFL, LED, UV, or even old-fashioned incandescent. While this could be as simple as putting it in a sunny spot, Casimiro has also built an LED/UV light exposure box to allow for control over the duration and brightness of the exposure process.

From there, it's as simple as washing the oily paper off the board, cleaning it, immersing it in developer solution, and etching it in a chemical etchant — then using paint thinner or acetone to clean the remnants of the inkjet ink off before drilling holes ready for components.

Casimiro's full guide can be found on Instructables.