Probably everyone electronics hobbyist is dreaming about fast PCB prototyping method. Some of you are just ordering professionally made PCBs, that is not always worth of cost; other are using an easier way – The laser printer toner transfer technique, which is not very accurate; the third option is more advanced – ultraviolet light exposure of photo-resist coated PCB through film mask. This gives pretty good quality at a reasonable price and doesn’t take much time.
The main thing that is necessary and expensive – the ultraviolet light source that is needed to expose a sensitive layer of PCB coating. You can buy light source, or as a hobbyist, you can build one. Scienceprog has published an excellent project on how to build an Ultraviolet light source. It uses 8x20W light tubes that give a total 80W for one side. So the exposure time is just three and half minutes. The device can be used for double-sided PCB exposure. And can produce a large number PCBs at once. Probably many of you may not need such a big device, but some design ideas may be helpful. An embedded part of this project is a countdown timer with LCD built on the AT90S2313 AVR microcontroller, which can be replaced with newer ATtiny2313. It is a simple timer which allows setting minutes and seconds. It controls a relay that switches lamps ON and OFF after timer counts to zero. Project files can be download here.