www.clarvis.co.uk
Design & Technology Resources
©2011 E.Clarvis
This page is all about how to make a PCB (Printed Circuit Board). In an exam you may be asked to describe the stages and describe why it is necessary to wear protective clothing. You may also be asked to describe how you would check that the PCB is of a good standard - this is called QA (Quality Assurance) and QC (Quality Control) but we will come to this later.

The chemicals used in PCB manufacture are not pleasant and can be quite dangerous. You must therefore always wear goggles, gloves and an apron to protect yourself and your clothes. Apart from being very caustic the chemicals used can turn your skin orange and it doesn’t wash off. So unless you want  “Dale Winton hands” - beware!

PCBs are made of laminations (layers) of different types of material. The diagram below shows an exaggerated cross section view of a brand new piece of PCB:

The fibreglass gives the PCB strength and is an insulator

The copper layer is etched in a way to form the tracks of your PCB design

The light sensitive layer is used to protect parts of the copper during the etching process.

The protective plastic film prevents the sensitive layer from becoming damaged by sunlight.
Fibreglass base
Thin copper layer
Light sensitive layer
Protective plastic film
Blank board
Exaggerated side view of a new piece of board
UV Light Box
Etch Tank
Shear
Production Chemicals
Bench Drill
Print the PCB design onto a sheet of transparency and cut to size. The transparency with the design on is called the mask.
Cut a sheet of blank circuit board to size using the shear.
Design your PCB using a program such as Circuit Wizard.
Remove the board and wash the developer off with water.
Now place the board into the etch tank.

Remove the protective plastic layer from the top of the blank circuit board. This will then expose the light sensitive layer.
Place the mask and blank circuit board into the UV light box.

It is important to make sure that the mask is the right way around or you will end up with a mirror image of what you want!
Close the lid and set the timer to around three minutes.

The UV light will now shine onto the parts of the board that are not protected by the black lines and shapes on the mask.
Remove the board from the light box and place into the developer solution.

The parts of the board that has been exposed to the UV light will react with the developer and come away, this usually takes about 30 seconds. When it is done you will be able to see the design showing through.
The tank heats the etchant (Ferric Chloride) and sprays it over the board. This helps the process to work much quicker.

The exposed copper parts will be etched away but the parts protected with the light sensitive layer will remain.

It usually takes about 10 minutes to etch a board but this is dependent on its size.
Remove the board from the etch tank and rinse off the et chant.

You will now be left with a finished PCB (Printed Circuit Board).
The PCB can now be drilled.
A finished PCB
1
2
3
4
5
6
8
10
7
9
11
12
To make a PCB you need the equipment shown below., you will also need to use the safety equipment shown above.
Making Circuit Boards (PCBs)
The Process