A few of our group in Boulder, CO, joined a workshop hosted at the Solid State Depot on the electronics design process, making our own printed circuit board (PCB). The first class went over how to actually design circuit boards before we etched the copper boards and soldered on the parts to make it all work. Actually etching the boards and building the circuits was the best part! First, after you have designed your circuit and created a sketch of how the copper board should look, you want to get that drawing to your copper clad board. And you can do that with a laser printer.
Laser printers work with etching your own circuit board because of how they print onto paper. Laser printers are different than inkjet printers in how they use toner with plastic in it that is melted on to the paper in the printing process. Because of this, you can, in turn, melt the plastic onto a copper clad board and then remove the copper around it. After printing the sketch, you can use an iron to melt the sketch onto the copper.
First, we prepped the copper with 320 grit sandpaper, sanding until it was shiny. Then cleaned the surface with 100% acetone. Once the board is prepped, place the printout sketch facedown and iron away! (but remember to use a LOT of pressure. really…)
After ironing, drop it in some water to soak the paper for removal. When you peel the paper off, you will see if you used enough pressure and if not, start over again! You can clean off any parts that did stick with acetone.
Once you do iron correctly, and it took our group 3 tries, the sketch will stick after you peel off the paper.
You’ll notice there was still plenty of paper, so we scrubbed it off with water and a toothbrush until the only thing left on the board is the plastic toner.
Since the etching process removes copper from the copper clad board that isn’t covered, you want to make sure that the board is covered where you want the copper to stay. So if there is a mistake, you can fill it in with a sharpie. We also sharpied the edges to make etching faster (less copper to remove). We didn’t realize it at the time, but in the next workshop, we would be sawing off the edges anyway.
Now the most boring part of the entire project, etching. You basically soak your board in Ferric Chloride until the copper that you left exposed on your board is gone. And it takes a while…
Once this part is done though, you just clean off the plastic toner sketch and any remaining sharpie and you are ready to saw off the edges and solder on some resistors!
In the next post, we’ll include what we did to solder everything on.