Here is a comprehensive guide to making your own PCBs at home using materials that are readily available in shops and online stores. While it addresses single-sided PCBs, it can be extended to create double-sided PCBs as well. The steps involved in making single-sided PCBs, in that order, are:
1. Create a schematic
2. Create a PCB layout
3. Create the artwork
4. Transfer the artwork onto the PCB laminate; let’s call this stage ‘artwork transfer’ or
‘exposing the PCB’
5. Mask the area where you want to retain copper. This stage is called ‘developing’
6. Remove copper from the PCB laminate where you don’t want it, e.g., tracks, etc. This
process is called ‘etching’
7. Remove the masking material to reveal the PCB
8. Drill holes to solder and mount components and accessories or sub-assemblies. This stage may not be required if the PCB is being prepared for surface-mount components
9. Tin the copper tracks to avoid oxidation of copper
10. Deposit some sort of protective material on the side of the PCB that contains copper tracks, also called ‘solder side.’ This material does not allow solder to stick to the copper tracks other than where solder needs to stick, like component pads. This process is called ‘masking’
11. Print the ‘silkscreen’ on the components side of the PCB to mark the component references corresponding to the components in the schematic
This article detail steps 1 through 8 as these are sufficient for most applications and can be performed at home.
However, your project circumstances and requirements will determine the steps that you need to perform. For example, if the artwork is already available, you may skip steps 1 and 2 and jump to step 3.
Fig. 1: Finished home-brewed PCBs
Step 1: Create a schematic
The prerequisite for this step is that the circuit for which you want to create the schematic is available along with component details like values, power rating and package details (size of the component, the spacing and layout of its connecting pins, etc). If that’s not the case, you may consider using some kind of simulation software like LT Spice or Proteus to draw the schematic and perform simulation on it. This may save you both time and money as:
1. Experimenting and reworking of a software simulated model is far less time consuming than procuring all the components that would be required for designing your circuit
2. You need not buy the components till you simulate and check everything theoretically to a large extent on the software.
If the components are handy, you may even use a general-purpose breadboard to quickly wire the circuit and test it. So let’s say that you have the circuit for which we wish to create the schematic. At this stage, you may want to consider using some kind of software tool for drawing the schematic on the computer. As you will soon realise, there are several advantages to using this tool as it works well beyond merely as a drafting or drawing aid. Eagle CAD, in particular, is extremely useful as it helps you create great schematics and much more. Its free version has some limitations like the maximum PCB size (board size) of 10x8cm2 and only two signal layers allowed. Even with these limitations, the tool is sufficient for most constructional projects.
Fig. 2: The full schematic
Eagle comes with loads of goodies like a huge device library, several third-party libraries from manufacturers, built-in scripts that can perform many critical static checks, generate bill-of-materials and Gerber files that can be sent to a PCB manufacturing house, and much more. You can find loads of information and tutorials on YouTube and other web resources about Eagle CAD and similar software tools. Note that Eagle tool is used here for illustration purpose only, and you may use any other suitable tool of your liking, like Proteus.
By now you should have a schematic like the one in Fig. 2. Here Fig. 3 is a close-up of the top right corner of Fig. 2. Eagle also provides a very useful feature called ‘electrical rule check’ (ERC), which can be used to test schematics for electrical errors and warnings. You will be surprised to see the number of warnings and errors reported by the tool for the schematic that you prepared and thought was perfect.
Fig. 3: The schematic zoomed-in view of the upper right side of the full schematic
Step 2: Create a PCB layout of the schematic
You may choose to use either through-hole components or surface-mount components (see Fig. 1), or a combination of both. This step remains the same for both types of components, except that some extra precaution needs to be exercised for through-hole components. Many software tools like Eagle allow you to import all the components from the schematic created by you to the board layout view while concurrently validating the board layout view (aka board view) electrically against the schematic. In this view, the board boundary is displayed, with all the components placed outside it, to begin with.