What is an electronic hobby project without a PCB (printed circuit board)? So one of my first projects was a pcb station.

The ideia was to have two heated containers, one for the sodium hydroxide and the other for the ferric chloride and something to agitate the solvents.

The result is this 2 liter, glass station with a 200 W silicone heater glued to one of the containers and pressed against the other one. A aquarium air pump agitate the solvents and some pieces of a garden plastic fence hold the board in place.

The silicone heater plays a important role on the system as with temperatures near the 35 40º C the eating of the copper is match faster then in ambient temperatures. The example PCB of the video was in the ferric chloride for a couple of minutes.

The process using the positiv 20 , the UV lamp and the ferric chloride is well commented through the internet. It is a very sensitive process as it has so many parts that could go wrong: from the layer of positiv 20 that have to be homogeneous, to the amount of time exposed to the UV light that has to be related to the percentage of sodium hydroxide in the water. But despite that here is how i do it with the UV process.

1. Scrub the copper plate with a steel wool and then clean it with soap
2. Dry the copper plate but not heat it, as the positiv 20 has to be liquid on the copper plate
3. Turn off the lights and apply the positiv 20 spray as homogeneous as possible in a horizontal position
4. Let it dry for about 10 minutes as it will became homogeneous for it self
5. Then heat it for 10 minutes in an oven
6. Get some WD-40 on the inverted drawing of the circuit to make it more transparent
7. Apply the UV light for about 40 seconds (the amount of exposed time is related to the layer of positiv 20 on the copper plate)
8. Put the plate on the first container with a weak solution of sodium hydroxide and water, and turn on the bubbles.
9. Then if there is no shadows on the drawing, the plate will go for the point of no return, the ferric chloride’s container

Actually now i make my PCB work with the heat toner transfer process. It is much easier and the results are better than those with the positiv 20 process. With the heat toner transfer i use the two containers as well, but the sodium hydroxide one now has only water to detach the paper from the copper plate after getting it through the heated laminator.