Electronic boards ( PCB ) are present in all modern electronic devices, since they allow us to make all the circuitry of the devices in an organized and solid way. If you are a “handyman” and want to make your own custom PCB for your home projects (or not), in this tutorial we are going to tell you what are the steps you must follow to achieve it.
Before starting you should know that there are companies that are dedicated to manufacturing these custom PCBs for you; You just have to send them the design and they will take care of the rest, making things much easier, although, for a price. However, in this tutorial what we are going to teach you is to make a custom PCB at home, although it is true that of course you will need to have some tools that, really, not everyone has at home in a normal way and Therefore, it is aimed at DIY enthusiasts (do it yourself, do it yourself) who already have some knowledge about it.
What is a PCB and what is it used for?
PCB stands for Printed Circuit Board , also called electronic board or printed circuit board. It is a surface made up of paths, tracks or buses of conductive material laminated on a non-conductive base, that is to say, it is nothing more than a connection plate in reality to which the components of the device to be manufactured can then be welded. We could say that for example a PC motherboard actually consists of a huge PCB.
Printed circuit boards are used to electrically connect different electrical components through conductive tracks, while mechanically supporting the set of components by means of the non-conductive board.
For example, we could make a PC motherboard by simply connecting all the components directly by cables, but in addition to being a tremendous mess of connections, it would all be “on the air” with nothing to support it; With a PCB we get everything to be organized, with easy access and also on a solid and resistant surface.
The manufacture of the PCB and the assembly of the components is generally automated , allowing its mass production and making the assembly much more economical and reliable. However, this does not mean that you can make your own PCB at home if you have the right components and enough skill to do it, so let’s see how it would be done if you decide to do it.
How to make a custom PCB
Obviously, the first thing you have to do is design the PCB , which can be more complicated or simpler depending on what you are going to use it for (this is up to you). You can use programs like EasyEDA or PCBWizard , but also with very advanced tools like Autodesk Eagle . We are not going to go into the software part, but of course you must have the electrical diagram ready to know how to manufacture the custom PCB beforehand.
Once you have the design made in the software, you will need a laser printer to print it (be careful because an inkjet printer is not worth it for this because of the sediments it leaves on the paper) in the form of a mirror and you must make sure that you print it on a paper with a glossy finish (you can reuse, for example, a magazine cover for this).
Once you have this ready, you will need a piece of CEM copper cut to size to fit the template you just printed. You must make sure that the copper surface is as smooth as possible and that it is completely clean; To do this, clean it well with a scouring pad and dish soap, rinse it and dry it completely with kitchen paper or a dry cloth. Once dry, go over the entire surface with rubbing alcohol to remove any remaining residue.
Now comes a very delicate step because the quality of the printed circuit depends on it: on a folded sheet, as shown in the following image, you must put the copper piece and the printed circuit diagram on top; We remember that it is important that the paper has a glossy finish and that the printing has been made with a laser printer, and in the next step you will see why; Place the print side on top of the copper foil and fold the paper.
Now what you have to do is place it (try not to move) on top of a smooth and hard surface that does not burn easily, such as a wooden plank, and literally iron it with a clothes iron at maximum power. With this, what we will achieve is that the impression of the circuit design is detached from the shiny surface that we have used and, with the heat, it is transferred to the copper foil.
With about 5 minutes applying heat (or less, depending on the power of the iron) will be enough. Then, very carefully and with protection, you must put the copper sheet with the glued paper in cold water so that it peels off.
When it cools you can remove it and when you remove the paper you will see that the print has been etched on the copper plate. If you see that the impression of the scheme has not been completely transferred to the copper plate, you can go over the lines or points with an indelible marker, preferably black (so that it shows more on the surface).
Now you need a bit of chemistry , and for this you will need hydrogen peroxide , powdered citric acid and common fine salt. In a plastic container, you should add 100 ml of hydrogen peroxide, 30 grams of powdered citric acid and 5 grams of salt. Stir carefully (don’t worry, it is not toxic) until it is a homogeneous mixture.
Now you must leave your copper plate in this solution that we have created; A chemical reaction will occur (which you can speed up if you heat it up a bit) and you will see that the electronic board starts to bubble gently and turn green (no, PCBs are not usually green because of this) and after a while, blue.
The green / blue color is because the chemical reaction is separating the copper from the CEM board, and you will know the process is over because the board is now translucent. It should look something like this, and you will see that the black print (and / or the permanent marker) is precisely so that the copper part underneath them prevails over the chemical solution. In other words, now the translucent part is not conductive but the black part is.
You practically have your custom PCB ready, but now you will have to remove precisely the toner / marker, and for this you can simply do it with a cotton ball and alcohol. You will see that under the black, the conductive copper appears.
Now you can use a small drill or electric punch (more recommended, in fact) to drill the points where the components should be welded.
Although we already have the copper lines made and they are conductive, it is advisable to review them using tin with the help of a soldering iron.
Once this is done, you already have your custom PCB completely finished and you can solder the components you need according to the design you have made.