From VoidWarranties - Hackerspace Antwerp, Belgium
The chemicals we use from left to right: Ferric Chloric Acide, soda water 20mg / 1l, stronger soda + baking powder
To make PCB's we'll use acid to etch them. In our case we use Ferric Chloric Acid (Iron(III) chloride, FeCl3). This stuff will leave permanent marks if it touches your clothes, and can eat away metal objects if they come into contact. This stuff is also corosive.
Wear a lab coat / bad cloths, and wear gloves. If you don't want to wear gloves make very sure you take your rings off your fingers.
DO NEVER POUR THIS STUFF DOWN THE DRAIN, IT WILL EAT AWAY METAL PIPES. It should be disposed off as toxic waste.
No toxic fumes are released when you use it at room temperature.
Never put the Ferric Chloric Acid in a club mate bottle, the metal cap will disappear.
Step by step manual
print the negative PCB out on a transparent sheet. You can cut it in 2 or in 4 and select A5 or A6 paper on the printer. This saves some money. Only one of the sides can be printed on, it's the side that is a little less reflective. If you print on the other side the ink won't dry. Select photo gloss as paper, and photo quality as print quality. The black parts will be removed, and the white parts will be copper.Step1:
cut the PCB to size, and sand it with a sand paper (I used a 240) to sand away oxidation, and other stuff on the surface. Make sure the board is a little bigger as the PCB you designed. Don't touch the metal surface with your fingers after sanding it.
cut the PCB dry film to size, a little bigger as the pcb. Try not to put this in the light for too long (10 minutes is usually fine, but light also contains a bit of UV). Make sure to put the excess back in the tube ASAP!
put a piece of tape on either side of the dry film (better to use transparent home / garden & kitchen tape), and pull them apart, repeat until a transparent layer comes off the dry film.
apply the sticky side (the one you just removed the film from) to the PCB. Try not to make air bubbles underneat it. You peel it of and try again in case of too many air bubbles.
cut the edges of the dry film.
put a piece of paper on top of the dry film, and apply a hot iron to it for a couple of seconds.
put the transparent sheet on top of the dry film, and push them together using glass plates or a picture frame (not in this picture), and put the UV box 15cm above it. Light for 2,5 minutes.
After 2.5 minutes when you take your pcb out of the UV light it will look like this. You'll notice that you can see your PCB already. The next step will be to remove all the light area's on the PCB. Keep in mind that at this stage the PCB is still sensitive to light. Don't wait to long before moving on, or make sure you keep it in a dark spot.
before developping you should take another piece of tape (once again preferably the transparent one), and peel of the plastic protection layer on top.
put the pcb into the developper, this took about 20m for my small pcb (the developper is made up off 20g soda crystals / 1l water). It is ready when it looks like this (all the copper that has to be etched away in the next step is visible). Rocking the tank a bit will speed things up, as well as rubbing the surface of the PCB with your finger from time to time. If you think it's ready leave it in there for just a few more minutes to be sure.
put the pcb into the etching fluid, this took about 20m for my small pcb (this is Ferric Chloride Acid (this is the stuff you want to handle with care / not put your fingers in there / not get it on your clothes
). If it's ready it looks like this (all the copper on the uncovered areas is removed). If you think it's ready give it 30 more seconds to be sure. Once again gently rocking the container can help speed things up.
clean the pcb with some water, and put it into the gootsteenontstopper (please translate if you know the translation. If you don't have that, like I have, using a slightly moisturised piece of sand paper (240) will also do the trick. It's ready when all the blue dry film is removed.Step13:
drill the holes if needed, most of the time a 0.8 up to 1mm drill is used for this.Step13: