It didn’t take very long for me to get around to developing the board for this little project of mine. I designed the board layout in EAGLE, then printed it to a transparent plastic sheet, and was soon on my way etching.
The etching process is quite simple and actually quite common among hobbyists. Once the plastic sheet with the board layout printed on it is complete, it is then placed over the top of a photo-sensitive copper clad board. A light is then switched on over the board and layout, activating any parts exposed to the light. After eight minutes, the light is turned off, and the activated board is then submerged into a bath of water and positive developer. The developer eats away any light-exposed parts revealing the shiny copper underneath while leaving a green outline when the printed circuit once was.
After the development stage is completed and the board rinsed, the exposed copper is then etched away by some ferric chloride [FeCl_3]. After soaking in the chloride until all the exposed copper is gone, the board you are left with will look exactly like your printed circuit. The next step is to wipe away the last of the green coating to expose what’s left of the copper – acetone works well for this. The last part of this process is a relatively quick one: a bath in some liquid tin.
This liquid tin attaches itself to the easily oxidized copper and protects it from corrosion. This tin also has an added benefit, better soldering characteristics. At this point, the board is ready to be drilled, populated, soldered, and fit into an enclosure. The results are always quite nice to see as they have a higher quality than standard prototype boards.
In this case, my board turned out well (yet messy), but it worked! Board fabrication is always a pleasant learning experience that takes a long time to master – I have quite a way to go with all my jumper wires everywhere.
