Printed Circuit Board Fabrication (PCB FAB)

SAFETY - Risk Analysis

All the chemicals used are toxic and irritant to some degree.
Eye protection should be worn as well as protective clothing.
Wash your hands thoroughly after any contact with the equipment and again when the work is complete.
Food and drink should not be stored or consumed in the area.

Design the board layout and print it onto a transparent acetate sheet. If the printout is not very dark, it is possible to print two acetates and align them carefully to get better light blocking.

EXAMPLE
Select the correct size piece of photo-sensitive circuit board avoiding waste.
Peel off the protective layer.
Align the board and the transparency. If necessary, use sticky tape to secure the two together. Hint: Text should be readable. If you have mirror writing, it is the wrong way round.
Switch on the light box.
Set the timer on the light box to 130 seconds by pressing and holding down the up-arrow button. Once the time is near to 150 seconds, press the up/down buttons to get the time just right.
Place the transparency and the PCB into the light box and press start.
After the timer has counted down to zero, remove the PCB. Save the transparency for future re-use.

Place the board into tank 1 (below) for about ten seconds to dissolve away the photo-resist.
Inspect the board. The photo-resist coating may have dissolved away. If you can see the printed pattern and clean copper this step is complete. If not, repeat 9 and 10 until you can see the pattern and clean copper.
With fresh chemicals 10 seconds may be sufficient.
Wash the circuit board clean in the rinse tank. Press the yellow button to turn on the rinse water. Press it again to turn the flow off.

Etching Tanks

Place the board into tank 2. Press the "Bubble Etch" button to agitate the Ferric Chloride solution. This ensures even etching. Check the board after about five minutes.
If the copper has been etched away, this stage is complete. If there has been no change or only partial etching repeat steps 12 and 13 until the board is clean. All traces of copper should have gone leaving a clean bear board.
With fresh chemicals 10 minutes may be sufficient.
Use the rinse tank to wash the board to remove surpluses ferric chloride.

Place the board into tank 3. Check the board after a few seconds.
With fresh chemicals 1 minute may be sufficient.
If you can see clean copper, this stage is complete. If there is still a green gold layer of photo resist, repeat steps 15 and 16.
Use the rinse tank to wash the board clean.

Place the board into tank 4. Check the board after one minute.
With fresh chemicals 1 minute may be sufficient.
If the copper colour has been completely replaced with a silvery tin colour, this stage is complete. If you can still see any red copper colour, repeat steps 18 and 19.
Wash the board clean in the rinse tank.
Thoroughly clean and dry the board.

Clean yourself up. Wash your hands to remove any contamination.