I always used to solder my projects on the so-called 'strip-boards'. Although it's easy to make small projects very fast with this kind op PCB, it isn't the 'cleanest' option and it's bound to give lots of unpredictable problems when testing the PCB.

 

That's why I decided some time ago to start making my own PCB's and so I started reading on the internet on how to make them. The first project to use my newly aquired skills at was this UV-exposure box.

 

It is used in the process of making custom home-made Printed Circuit Boards. More specific, it is used to expose the photo-sentsitve layer of the PCB with UV light, to 'print' the schematic/pcb design onto the actual PCB. How does this work?  The PCBs are coated with a UV-sensitive photo-resist. The track pattern is imaged onto the PCB, using the photoplots (transparant paper) and UV light. The photo-resist is developed, leaving photo-resist only where copper is required. The PCBs are put in acid, to etch away unrequired copper, forming the track pattern. The bare copper PCB, with tracks and pads now finished, is cleaned.

 

The UV exposure box is made from an old scanner and an old face tanner, containing 4 lamps. There is a small LCD screen and a few push-buttons for control. The whole thing is controlled by an AVR micro-controller. More on this on the next pages..