Been having lots of fun the last few weeks learning my way around the process of designing and etching Printed Circuit Boards. We were shown the process by Marc Dusseiller one of the mentors on the Arts + Tech programme.
Initially I was exploring simple hand drawing circuits using posca ink markers but then learnt how to design boards in the Eagle software programme (there’s a free version of Eagle available if you follow through the link) Its a pretty useful tool as you can layout the schematic digitally and then eagle converts this into a mapping out of all the connections needed on the PCB; you just need to then route them manually to make sure no connections are touching. The design is then printed onto acetate and placed over a photosensitive blank copper pcb; this goes under a UV light (In our case a nice dayglo pink UV nails light as recommended by Marc!) and exposed for between 30 seconds and a minute. After exposure the boards goes straight into a developer solution for about 30 seconds. The developer is 1% solution of Sodium Hydroxide (NaOH) (Its basically a very diluted version of the sort of thing you unblock sinks with!) After this stage it goes into the etching solution Ammonium Persulphate (NH4)2S2O8. At this stage you need to add boiled water to a basin the etching solution is sitting in (in this punkrock version anyway; it is possible to rig up a water heater/pump solution) to bring the etching fluid up to a temperature around 50/60 degrees where it works better) It seems to be taking between a few minutes and 15/20 minutes for all the unwanted copper to be removed from the board, dependant on the timings on the previous stages.
There’s another nice detailed walk through of basically the same process here http://sfprime.net/pcb-etching/#development