For around £25, you can make your own printed circuit boards!

The theory is basically this: you take boards covered with copper, mask the bits of copper you want to keep, and etch away the rest in some sort of acid.

What You need

• Eagle PCB design software, or graphics program
• Press-n-Peel PCB film
• Access to a laser printer or photocopier
• Copper covered boards
• Plastic Etching tray
• Plastic tweezers, to lift board out of acid
• Ferric Chloride crystals
• Chemical storage bottle
• Miniature drill
• 0.8mm and 1.0mm drill bits

You can get most of the hardware in Maplin, or you may find it cheaper to order online from somewhere like CPC.

Draw the Circuit

If you are using someone else's design, it probably comes as a gif file or similar. You need a graphics program that allows you to flip and scale the image to suit your printer. IrfanView is very easy to use.

To draw your own circuits from scratch, you will neeed some sort of PCB layout software. The best free software around is EAGLE from CadSoft.

Print the circuit onto paper and try placing components onto it to see if they fit, then change the scale if necessary.

Cut the Board to Shape

Copper covered boards come in two main types, fibreglass and resin bonded paper (SRBP). SRBP boards are cheaper and much easier to work with. Cut them with a fretsaw, coping saw, file, craft knife and metal ruler, or for intricate shapes, nibble away at the board with a pair of snippers.

Print your design onto paper, glue it onto the board, then cut it to shape. Then peel off the paper and scrub the board with a brillo pad until it shines. Also make sure there are no rough edges of copper sticking up, as these can interfere with the masking process.

Mask the Board

Maplin and CPC both sell "Press 'n' Peel" film for around £8 for five A4 sheets. You print your design onto this using a laser printer or photocopier, then iron it onto the board. The toner melts onto the board, providing an acid-resistant layer. The film comes with detailed instructions.

Make sure you work out which way round to print your design! The image you print onto the film should be what you would see of the copper if you could see through the top (component) side of the board. Your graphics or PCB design program should allow you to flip your image, if necessary.

Etch the Board

There are many chemicals that can be used to etch the design onto your board. The cheapest, most common one is Ferric Chloride, FeCl2. This has the advantage of being a horrible sludgy orange colour so you know where you've spilt it. But try not to, as it stains anything it comes into contact with. It usually comes as crystals that you can dissolve in water. Please read the warnings on the etchant packaging as it is nasty stuff. Rubber gloves and safety glasses are highly reccommended.

The etchant works best if it is slightly warm. If you are in a hurry you can place the etching tray in a sink or bath and surround it with hot water. It still works fine cold but can take upwards of 20 minutes, especially in winter. This gives you more control and makes it much easier not to over-etch the boards.

Simply place the board into the etchant and check regularly, using plastic tweezers or similar to lift the board. When all the unwanted copper is gone, wash the board well, and then scrub the acid resist (toner) off with a brillo pad.

Drill the Board

Use a model drill like the miniature archimedian drill from CPC to drill holes for components. 0.8 mm holes are fine for most components; use bigger ones where necessary.