this doc aims to explain how to make pcbs using the photo etching method on uv sensitive boards

• single sided photo resist pcb
• acetate (we have)
• az303 developer (we have)
• uv light box (we have)
• bubble etch tank (we have)
• ferric chloride 40% premixed (we have)
• a timer (attached with magnet to shelves above the bubble tank)

using eagle

• show the layers you need. I used top, pads, vias and dimension for a combo SMT and through hole board
• print from eagle to laser printer, click the mirror and black box
• acetate face down in laser printer
• make sure the print is black enough or you will have problems with the resist - you can try printing twice

• if you've had to cut the board down, make sure it's flat with a file or you may get uv leaking under the acetate
• peel off protective cover on the board
• line up the artwork on the board. You may want to hold it in place with tape
• make sure it's the right way round!
• put the board down on the uv lightbox glass with the acetate between
• set timer for 1.5 minutes, press go

• If you see pitting in the resultant mask it's because you exposed for too long or the acetate wasn't dark enough

we don't have a slot for this in the etch tank so we do it in a shallow tray

• put the board in a shallow tray
• cover with the developer
• leave for 2 minutes
• wipe off developed mask and rinse in water

• turn on the tank and the heater
• set the thermostat to 4 and wait for heater lamp to go out
• put board in the mesh holder and immerse in the ferric chloride
• turn on the bubble pump
• wait for until etching is complete (at least 3 minutes). timings vary on size of board, temperature and as ferric chloride is used.
• clean off the mask with acetone