You'll need the following ingredients:
- laser printer/photocopier & transparencies (I go to a print shop to do this)
- copper board (local electronics store)
- scrubbing pads (SOS or a generic brand is perfect)
- rubber gloves (like the ones you use for washing dishes)
- Ferric Chloride or Ammonium Persulphate (local electronics store)
- drill and drill bits
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Step 1: Design and Print
Design your PCB. I use anything from Adobe Illustrator to Cadsoft Eagle. Once you think everything is perfect, print it on a piece of paper and test it by placing your components over it. You have to 'flip horizontal' your final design so that the transfer from the transparency to the copper board 'restores' the intended design... Then print it on a transparency. It has to be a laser printer or a photocopier because we want toner on the transparency. If you can, ask the guy at the print shop to make it as dark as possible (more toner). I've noticed that I've had the best results at the worst print shops in town.
Step 2: Transfer the Toner
Now you want to transfer the toner (mostly made of molten plastic) onto the copper board. Set the iron to 'silk' (you'll have to experiement with the temperature...it took me quite a while to consistently get good results).
Clean and rinse the board with the scrubbing pads and soap. Dry it up. Place the transparency on the copper board, place a piece of paper on top if it all and start ironing! Depending on the size of your circuit, it takes about 2-3 minutes for the copper board to get hot enough so the toner sticks to it. When you think you're good, immerse the copper board (with the transparency stuck to it) in cold water. Then you should be able to peel off the transparency while the toner remains on the copper board.
If the toner did not transfer completely, you didn't iron long enough and/or didn't set the temperature high enough. If the toner transfered but is smudged on the copper board, the temperature was too high and/or you ironed for too long. You can use a Sharpie or any other permanent marker to fix parts of the circuit that did not transfer properly.
Step 3: Etch
You're almost done. Put the gloves on, pour some etchant in a plastic or glass container and immerse the board. At room temperature, it can take up to half an hour. Mixing the solution as it's etching can speed up the process. Another good way to dramatically decrease the etching time is to warm up the solution. Now I strongly discourage you to get creative with the microwave or your precious pots and pans. You can however dip the container in warm water poured from the tap. When it looks good, clean the board in running water.
Step 4: Clean
Use the scrubbing pads to remove the toner from the board.
You can reuse the etching solution, so just pour it back in the original container. Do not pour it down the drain! It will corrode your copper pipes... Over time, the etching process will take longer and longer. When the solution becomes unusable, contact the waste management organisation in your community to know where to dispose of the chemical.
Step 5: Drill
For those of you who do not use surface mount components, you'll need to drill holes in your board. I use a Dremel (you can find generic versions for less than 40$). You'll need tiny drill bits (#66-#60). Most places you'll go to will rip you off with those tiny precise bits (10-15$ each). However, some places like Lee Valley sells them for ~$0.50 each.