Ultraviolet light box for PCB exposure

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.

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