I’m going to put this guide up mostly for myself so I can repeat my successful PCB fabrication.
I’ll try to update this with links to sites for each product and pictures of my going through the process the next time I do!
- Laminator ($75 on Amazon)
- Copper Clad Board – any will work ($1.56 for a 6″x6″ from Tayada Electronics)
- PCB Etchant – your favorite mixture ($11.49 for FeCl from RadioShack)
- Isopropyl Alcohol ($2.29 at Walgreens or similar drug store)
- Acetone ($7.48 at Home Depot)
- Pulsar Toner Transfer Paper ($14.95 from Pulsar)
- Pulsar GreenTRF ($8.95 from Pulsar)
- Laser Printer – use yours or a copier/printer at a FedEx Kinkos or similar – DO NOT USE Brother brand printers or InkJet printers
- Bowl of warm water
Step by Step Guide
1. Design the Circuit
I’m not going to include this as part of the guide. There are plenty of tutorials on circuit creation using your favorite CAD program. I use Eagle myself. Create your circuit, double check it, triple check it, then continue on.
2. Print the Design
There are 2 secrets to good toner transfers. 1 of those secrets is the paper. The goal in toner transfer based PCB etching is to get the toner from some carrier paper onto the copper clad board. Toner is made up of a plastic that melts when heated. Once the toner melts it embeds itself into whatever it is touching. The trick is to get it to want to attach to the copper clad board and forget completely about the carrier paper. The ideal paper is slick, glossy type papers. The reason being that toner can’t ‘grab on’ to anything on glossy papers, it will stick, but not embed completely. Many people use Inkjet Photo Paper (yes Inkjet paper in a laser printer). They do so because the paper is super glossy, AND when put into water the glossy paper wants to release itself. I’ve had pretty good luck with the glossy paper, but only when the toner sticks to it long enough to get the toner onto my board. In my printer the toner just wants to fall off photo paper.
Solution? Pulsar Toner Transfer Paper. This stuff is awesome. It has a special Dextrin coating on the paper that is completely safe to pass through a laser printer. What is so special about the Dextrin coating? It is glossy and it allows the toner to stick to it pretty well. Better yet, the dextrin coating completely dissolves in water. You’ll see this in action soon enough.
In this step just print your design onto the Pulsar Toner Transfer Paper using the darkest setting for black toner that you possibly can (on my printer it wasn’t easy at all to find this setting). The only tricky part of this step is minding whether or not the image needs to be mirrored. This will depend on the CAD software you are using. The toner transfer process in itself mirrors the image but keep this in mind. Traces on the bottom of the board need to look just like they do on your screen when they are printed on the paper. Traces on the top of the board need to look mirrored when printed. This will cause bottom traces to be mirrored when they transfer and the top traces to un-mirror when they do.
Make sure you print onto the light blue, slightly sticky and shiny side of the toner transfer paper.
3. Prepare the Copper Clad Board
Now you need to prepare the copper clad board. Take the board and either fine grit sandpaper or a scotchbrite pad and scratch the surface fairly good. This will help the toner stick to the copper. Then you need to clean the board VERY WELL with Acetone, then clean off the Acetone with everyday Isopropyl Alcohol.
4. Transfer the Design
You’ll need the laminator for this step so I would start heating it up now. You want to wait until it gets really hot, and the ‘Ready’ light on most of these turns on way before it gets hot enough for us.
If you haven’t guessed already, this is the other secret to beautiful toner transfers, the laminator. You simply place the toner transfer paper onto the copper clad board with the toner face down (toner ON the copper) and run it through the laminator several times.
5. Release the Toner Transfer Paper
This is one of my favorite parts. Place the copper clad board (while it is still hot) into the bowl of warm water and wait for the paper to release. This can take anywhere between 30 seconds to 3 minutes. I’ve had the paper literally float right off with no agitation and sometimes I have to pull it off as it gets sticky and sucks onto the board.
Once you get the paper off, dry the board with a paper towel. Don’t be afraid to rub the board. If the toner falls off at this point it is a failure, the toner SHOULD stick VERY WELL to the copper clad board.
6. Seal the Toner
Toner doesn’t transfer 100% perfectly. The lines will look good and crisp but if you transfer the board right after step 5 you’ll get what is called ‘pitting’. Pitting is when the etchant gets through in some areas of the toner and cuts small grooves and dips into the copper. If you are doing very large traces (20+ mil) you probably won’t care (I don’t when I do that large of traces). But if you are doing very small traces (8-15 mil) you’ll want to pay attention to this amazing trick.
Pulsar makes a special foil called GreenTRF for filling in the gaps that the toner itself creates. To use it you do something very simple. Cut the foil to size for your board, and then run it through the laminator. The only tricky part is keeping the laminator from crumpling the foil as it goes in. I find that pulling against the foil softly as it goes into the laminator helps. Just practice and you’ll get it. You can always run a new piece of foil if you mess up. The foil only sticks to toner apparently. Sometimes you’ll get foil that looks like it bridged or gapped some traces, it’ll wipe right off with a toothpick or cotton ball.
7. Etch the Board
Finally, the fun part. We are about to have a homemade printed circuit board!
This step you can use whatever etchant you prefer. I’ll describe using Ferric Chloride since that is what I have right now. I’m looking into other etchants since this stuff is pretty dangerous.
Heat up some ferric chloride and put it into a small plastic tube with just enough to cover the board you are about to etch. Constantly agitate the board while it is etching. The more movement the better. You’ll want to keep grabbing the board with some tweezers or something to see the progress. You don’t want to over etch. The etchant can and WILL get under the toner if left for too long. Pay close attention, keep moving the solution, keep checking the progress and in a few minutes you’ll have a complete board.
WARNING: Most etchants are very dangerous. Always wear gloves, most will suggest wearing glasses too, I don’t but gloves are needed. This stuff stains everything, including skin. It is toxic and obviously eats away at metal. DO NOT pour down your sink. Improper disposal is illegal in most areas (including garbage, sink or other drain, and dumping in your yard or similar).
Congratulations on a finished homemade printed circuit board! Each and every board I’ve created is rewarding. It is a very nice feeling to go from concept to prototype to (hopefully) mass produced product. Have fun.
As always if you have any suggestions, comments and/or concerns feel free to comment below. I read all of them and will respond to any that I can!