For some time now, I've been making my own pcb's. They're all pretty small and simple, like the powersupply for my headamps or the tda-2040 amp in my speaker test jig. I found a cheap way to make them, without much equipment. Most of the info here can be found on this webpage: Easy Printed Circuit Board Fabrication
What's needed, is the following:
- Some printed circuit board, without a photolayer
- premium inkjet paper, or comparable
- (access to) laserprinter
- Clothes Iron
- Ferric Chloride, or Ammonium Persulfate for etching and a small tank or small container
- scrub sponge
- optional: pcb spray
Some stuff that's needed:
First thing to do is to print the circuitlayout with a laserprinter (use the darkest possible setting, so you get lots of toner on the paper) on HP premium inkjet paper. Don't use ordinary office paper, I tried it: didn't work. The original webpage says premium photo paper, but that stuff is 4-8 times as expensive, and the premium inkjet paper works just fine. The trick is to use some coated paper, so the toner will come loose when heated.
When that's done, cut the pcb to the correct size. Scrub it with some household cleaner and a sponge. You can see the pcb changing color somewhat. After that, degrease thoroughly with aceton. Don't use a cleaner that leaves a residu: that spoils the whole point of cleaning.
When that's done properly, place the paper with the toner side down on the pcb and heat with the iron on the highest setting. Heat for about 30 seconds and make sure that you've pressed on the whole surface. When you've done that, the paper will stick to the pcb.
Now it's time to remove the paper from the pcb again. This is easily done by throwing it into hot water. It works best when the pcb is still hot from the iron.
Here's an image of a submerged pcb. after a few seconds, the traces will shine through the soaked paper. You can help this a little, by rubbing over the paper.
After that, the paper will peel off easily. Inspect the traces thoroughly, to see if they have transferred properly.
And that's all. Once you get the hang of it, it will take about 5 minutes. And you don't need expensive UV lighting or the more expensive UV-sensitive boards.
The etching itself is not so difficult, but please do it outside of the house. If the etching stuff gets on your hands and you touch something made from metal (like a doorhandle, or the kitchen sink) you're in some real trouble!
I use ferric chloride, but when this wears out, I'll switch to Ammonium Persulfate. I use 2 containers. One small, one larger. This way, I don't spill the etching fluid all over the place. I put boiling water in the larger container, this will then heat up the smaller, so the etching goes quicker. I stick the back of the board to a piece of tape, so I can move it around in the fluid and get it out at the end. It's quite easy to see when the etching is done, because the copper between the traces will have disappeared. (so the pcb visible in the right image needs another few minutes)
When that's done, clean it with water and dry it. This is the result of the small tda-2040 amp pcb:
Next up are the holes. I tape the pcb down to a small piece of mdf. This way, I can drill through the holes and it also stays in one place. But before the drilling, I make a small guidance hole with the bit you can see in the image. It helps with centering the small drill later and this means that the drillbit wears down less quickly. The drillbit sizes I use most are 0.8mm and 1.0mm.
Now all that's left to be done is to remove the toner. Aceton works just fine for that. I always spray some sk10 from kontakt chemie on the board. The stuff prevents the copper from corroding and also acts as soldering flux.
And that's all! In less than an hour and with less than 10 euroos worth of materials. No more experiment hole boards for me. I can now work out the layout on the pc instead of guessing what a good layout will be on experiment boards. And it looks kinda professional too :)