During my University days, we learned how to design and create printed circuit boards. There are many ways to do this and the main principle is the same: remove the unwanted copper metal from the media. The solution is to create a barrier where the etchant could not react to it.
THE BASIC METHOD
This method is by using a permanent marker to write onto the copper board. The result is crude and the copper tracks are limited to the thickness of the marker’s tip. It also has a lot of broken tracks.
THE TONER METHOD
This method transfers the toner from the paper onto the copper board via heat. The result is a marked improvement over the marker method. But it has additional and boring steps to transfer the toner and then remove the paper from the copper board.
THE CNC METHOD
This method uses machine to remove the unwanted copper tracks. It is very accurate but slow and costly. It is also fun.
THE PHOTOLITHOGRAPHY METHOD
This method uses ultra-violet (UV) light onto a positive film to create an acid barrier layer on top of the copper board. There are additional steps to develop the barrier before etching. The results are very, very good and depending on the equipment, can produce very fine copper tracks. Professional solutions and Electronics Industry uses this method.
Still, with the four methods above, we’re talking about creating ONE side of the PCB. If you’re doing both sides, the preparation is much more demanding since you would need to be very accurate. So, I just design my board and then leave it to the professionals like JLCPCB. With them, you can:
Specify the mateial fo the baord from FR4 to aluminum
Specify the thickness of your board (standard is 1.6mm)
The colour of your board (OK, so it’s solder mask)
Through-hole plating as standard
Assembles your board
Allows for custom shapes and so on.
CREATING A PCB DESIGN
For the Toner and also the Photlithography method, we need to have a circuit board pattern. Modern solution uses PCB software to achieve this. There are many solutions but I am going to tell you about the one I am using: CADSoft EaglePCB ver 7.77
The software was around for a very long time and by 2016, AutoDesk acquired it. It took me quite some time before I accepted this software as I was using Easy-PC. The EaglePCB is user-friendly and there are a lot of support for it. PCB manufacturers such as JLCPCB shows you how to convert the files into the Industry standard Gerber files.
The basic EaglePCB software is free to use. Their limitations are:
You can only design a 2-layer board
It has working area of 100mm x 80mm (3.94in x 3.15in)
You are limited to a single sheet of circuit schematics.
Which is fine for a lot of Hobbyists including myself. Moreover, my design always falls below JLCPCB’s minimum board size of 100mm by 100mm.
The software falls into two main segments; the Schematic Editor and the pcb Layout Editor. Both are usually linked together and any changes from one segment is updated almost immediately. There is also the Library which you can create your own components and its package to be used on the pcb. I am barely scratching the surface but it does what I wanted it to do.
With the Autodesk current subscription scheme, many are moving away and most possibly, making KiCAD the next best PCB software. RIght now, here is a video from Binary Updates to show you how easy the EaglePCB software is. ONc eyou have seen it, the following notes makes more sense.
THE EAGLEPCB SCHEMATIC EDITOR
This is an example of my circuit which I am developing. Some area might be unconventional as there are a few parts that needs to be off the board but still needs to be connected.
The schematic editor let’s you create your circuit with the components of your choice. In this editor, after you have chosen your components, start connecting them from pin to pin. Then switch over to the layout editor and move the components to the correct position.
THE EAGLEPCB LIBRARY
I created my own 5739 SMD LED, added it to the Library and used the part into my designs. The schematic symbol is on the left while the actual component package is on the top right.
Some of the components are not in the library but you can search for them via Adafruit, Sparkfun or from SnapEDA before making your own. Here are some instructions from AutoDesk as well. Just to show you how easy it is, here is a sample YouTube video on making your own custom library.
OK, if you do not want to watch the video, here is another good example:
Downloadable EaglePCB Libraries: Eagle Part Design by Homemade Hardware
THE EAGLEPCB LAYOUT EDITOR
This is the screen you will see for the very first time after switching over from the Schematic Editor. All the components are linked and you just need to place them on the PCB. Here, the PCB size is roughly about 100mm by 80mm. Once the parts are placed and oriented, you can use the auto-router to generate the optimal trace.
When you switch to the layout editor after creating your circuit, half of your design process is almost done. In this instance, you can now define the shape of your circuit board and then move the components into its place.
The schematic editor let’s you create your circuit with the components of your choice. In this editor, after you have chosen your components, start connecting them from pin to pin. Then switch over to the layout editor, then drag-and-drop the components onto the board.
There is one thing you need to remember about the layout editor; you cannot delete or add components if the schematic was not done first.
You can still create your own pcb without going through the schematic editor. The only issue is that if you create the schematics later, the two of them will not update each other. Also, this means you cannot use the auto-router function.
THE EAGLEPCB AUTO-ROUTER FUNCTION
Once I am comfortable with the auto-router function, I started to use it more often. Before starting on this stage, I have to make sure the schematics are correct. For a circuit with a lot of traces, this function saves a lot of time and also, catches a lot of errors. The EaglePCB’s auto-router is good enough although it cannot give a 100% solution some of the time. Much of the software’s enjoyment came from my placing and re-placing the components and traces until I am satisfied.
In the beginning, I was quite wary of the function but after some and the pcb boards were working, I started to use it more often.
