Create Etched Printed Circuit Boards with an SLA 3D Printer
Photoresist resin acts as the acid resist.
When you think of creating a printed circuit board at home, the methods that might come to mind are milling or etching. For milling, you need to have a CNC router. Etching requires a way to apply an acid-resistant mask to the copper, which has various application methods. A new strategy from Pete Liwyj uses an SLA-style 3D printer to create the acid-etchant mask.
As Liwyj explains, "I had an idea. I was wondering if cured SLA resin could be used as etch resist for making my own PCBs at home. And you know what? Turns out it can be!"
Liwyj successfully used an ELEGOO Mars SLA-style printer. However, the technique should work on similar machines. Normally, these printers create each print layer with an LCD panel curing a photosensitive resin. Sounds simple, but the results are incredibly accurate 3D prints with very thin layers (compared to FDM printers.) As it turns out, the cured resin is an effective acid-resist!
Processing the PCB starts with cleaning the copper with a scouring pad and acetone. Then you add some photosensitive resin on top of the board. The next part is printer dependent. You have to trick the z-axis into letting you put the blank PCB between the screen and build platform. Liwyj provides instructions on how he accomplished it with the Mars printer. Once in place, only a single layer of exposure is needed to create the acid-resist mask.
The etching step is similar to other photo-resist processes. Liwyj used Ferric Chloride in his approach. A time-saving bonus is that the FeCl3 breaks down the uncured resin, so no additional cleaning is necessary between exposure and etch. In fact, Liwyj points out you should go directly from the printer to the etching tub.
The last production step is removing the resin mask and then drilling the holes. After cleaning up the chemicals properly, like with sodium carbonate (washing soda), you can solder parts onto your new PCB.
Since the bed size of these LCD-based SLA 3D printers is relatively small, this method is ideal for single-layer breakout boards. In Liwyj's case, he made an ATtiny breakout board. For more detailed instructions, check out this SLA acid etch Instructables write-up, or check out the YouTube video above from his PeterThinks channel.
