How to create PCBs

Over the past couple of years, I've had a couple of projects where I've designed and ordered PCBs. It's a great way to make more permanent electronics projects look and feel a lot less janky.

I've also come across a couple of open-source electronics projects where I had ordered PCBs from a project. For example, these drone timers (which I unfortunately am still yet to finish), and this drone controller screen adapter. It's super easy to download the design files from the project and upload them to a site and get them ordered - it's often a lot cheaper than finding them sold anywhere online (if they are at all).

I've also adventured into designing my own like a tiny DIY keyboard based on the ARTSEY.io layout.

For this post, I'll go over the basic principles I've learned for creating a PCB from scratch - from design, all the way to ordering. I like to use KiCad which is free and open-source, but there's lots of other great PCB design programs, both free and paid, even ones that work in your web browser. As far as I know, they all work pretty similarly, so these basics should transfer across.

The project I'll make here, is going to be a with a microcontroller, button and LED.

Building a schematic

First up, we need to build the circuit's schematic, this is a high-level overview of components and how they connect.

I'd actually usually start with a breadboard design before doing this, just to check it works in the real-world first, but you could also do this part after designing the schematic. It all depends how you like to work.

To get started, launch KiCad and create a new project. I've called mine simple here. You'll see it's automatically created files for the schematic (simple.kicad_sch), as well as the PCB (simple.kicad_pcb).

This post is just going to touch on the Schematic Editor and PCB Editor, but I'll give a super quick explanation for a couple of the other options:

• Symbol Editor - this is for editing symbols or components for use in the Schematic Editor. There's lots of built-in parts, but if a part you want isn't in there, you can use this to import it from someone else who has designed the part online, or create your own part from scratch.
• Footprint Editor - the same as above but for the PCB Editor instead. These footprints will likely be linked to symbols in the Symbol Editor.
• Gerber Viewer - Gerbers are the exported design files that we'll eventually send off when ordering. You can view them using this tool.
• Plugin and Content Manager - this lets you add extra components and plugins. For example, when I was designing my keyboard, I was able to find a component library for keyboard switches in here.

If you open up the Schematic Editor, you'll see a blank page with a lot of buttons around the outside.

First off we need to add components to the schematic. Use the 'Add Symbols' button on the right toolbar, which will bring up this window to select a symbol. A symbol is just a component in the schematic. For simplicity, I'll use a built-in one here, an Arduino Nano. The top right of the window shows the symbol as it will appear in the schematic, and the bottom right shows the footprint, which is as it will appear on the PCB. The dropdown in between the two previews lets you select a flavour of the footprint. For this Arduino Nano, there's just with mounting holes or without, but for more complicated components, you might need to select the size of component you're planning to use (e.g. size of a surface mount resistor or type of switch) - essentially make sure the footprint matches the real component you want to use.

After you press OK, click anywhere on the schematic to place the symbol. Now I'll add in a battery, button, LED and a resistor for the LED. The battery and button didn't have footprints for me, so I've left them blank and we'll sort them later. Here's where we're at:

I've moved all the components around so they are laid out better, then finally we'll add in a ground connection using the symbol underneath the one we just added. You could also add in a +5v connection if you wanted. I'm not sure if this is strictly necessary, but it makes the diagram slightly clearer and it may help out later on when we're putting a ground plane on our PCB (but more on that later...)

Now use the next icon down on the right to create some wires to connect all the components. Just click on one of the circles at the connection points on a component, then click one of the circles on another component.

Here's my final schematic:

That's pretty much all we need to do for the schematic, now just save it. You can also add labels to your diagram, using the label and global net label tools near the bottom on the right which can give your connections nicer names. There's not much going on here, but for more complex schematics it can help a lot with laying out things. It lets you have connections between multiple places on the schematic without drawing wires everywhere, just connect a global net label at each end.

Designing the PCB

So now we've got the schematic designed, we can move onto the PCB. Head back to the KiCad project window and open the PCB editor. This window also has a lot of buttons and things.

We can use this button at the top to import the components from the schematic. It'll give you a quick summary of what it's going to change (as you can also go back to the schematic and add more things later, then do this again to update the changes that have been made). Once done, you'll see the footprints added to the PCB.

For the few components that aren't shown, we can go back to the schematic editor and change the footprint to be used by double clicking on the symbol, then change the footprint by clicking the lines in the value box to bring up the footprint selector.

For anything missing, you might need to find something close, or find footprints others have designed online, or create your own. For the battery, I'll select a 2-pin header which will allow the circuit to be powered from an external 5v supply. Strangely, there is push button footprints available, they just weren't linked to the symbol earlier for some reason.

After making these symbol changes, redo the previous step again to import the new footprints. You'll notice some thin blue lines going between the components. This is how they should be connected together according to the schematic.

Now I would lay out the components to near the pins they are going to connect to. Once you're happy with the layout, click on the Edge.Cuts layer on the right side. As the name suggests, this is cuts that the manufacturer will make, so we want to put one around the edge of the board. If you're feeling extra fancy, you could add in rounded corners, mounting holes or other things. You might notice some of the components, for example, the LED already have holes where the legs go through the board.

Some of the layers have F & B prefixes, which means front and back. We'll use the F.Cu (front copper) and B.Cu (back copper) for traces between components and you can add printed text or images to the board using F.Silkscreen and B.Silkscreen (although remember to reverse text if using the back). Click on one of the copper layers then use the first blue line on the right toolbar to create a trace. You'll notice it'll helpfully highlight where it needs to go. Make sure to leave the ground connections for now, because we're going to make a ground plane to connect them all. Here I've used the back copper layer to run a trace along the back of the board because I've got two tracks that overlap. With more complex PCBs it can be a bit tricky to route everything around, but it's all part of the fun!

Now we'll use the copper zone tool which is the blue shape on the right that has a wire going into it. This creates a zone of copper on the board. We should add a ground zone on the board when we're done. This can help with any external interference on the circuit. Select either one of the copper layers in the window that appears, then select the GND net and draw a box around the board again. Finally, go to "Edit" then "Fill All Zones". You'll see the board now has copper everywhere, except where we've got the blue trace going through. And it connects up the ground pins on the components that need it.

Now I like to go to the 3D viewer (icon left of our schematic import tool) and give the board a check to make sure it looks okay and all the traces are connected up where they need to go.

There's also an automated checking tool named DRC which can help spot any issues with your board which I'd recommend using before ordering. But, I'm happy with this board, so lets go and order it!

Ordering the design

Once your happy with your PCB design, it's time to get it ordered. You can find a bunch of manufacturers online, but my favourite is JLCPCB which seems to be the most cost-effective for me. You can easily get boards created and shipped for under £10, albeit they take a little while.

Regardless of where you choose to order, we need to export the PCB to gerber files. This is what the manufacturer uses to make your PCB. In the PCB editor, go to "File", then "Fabrication Outputs", then "Gerbers (.gbr)". The settings in here depend on your manufacturer so make sure to check their website for suggested settings. Once dialed in, click "Plot" to export, then "Generate Drill Files..." and do the same there. You should have a bunch of files generated now.

You'll want to ZIP up the Gerber files now. I like to then take it to a couple of online Gerber viewers to double check the design again. For example, this one from PCBWay:

Now I'll upload the design to JLCPCB. You'll see a preview at the top of the design, and we've got a bunch of options to select. There should be similar options for other manufacturers too.

For the base material, you'll almost always want FR-4 which is just a normal board. We've got 2 layers on our board - front and back, but you can also get more expensive boards with additional layers of copper in the middle. The dimensions are automatically calculated, but double check to make sure they're correct. You can also select a quantity here. There will likely be a minimum order quantity - in this case 5, however it still works out cheap, even with 5 boards.

Now we can choose the board specifications, a lot of these options will affect the price of the board:

• Deburring/Edge rounding - whether the edges of the board are smooth or not. In this case it's only $0.10 extra to have smooth edges so I'd spend that to not have my fingers potentially cut up later.
• Different Design - this will almost always be 1, but if you have multiple boards in the same design you can save a bit of money by doing them all together.
• Delivery Format - this you'll almost always want a single PCB. Panels can be useful if you're doing a big operation and want boards to be stuck together for adding solder paste and components.
• PCB Thickness - most of the time 1.6mm is fine, being the cheapest option, although you may have requirements for your project that dictate another format. For example a PCB that needs to go inside a USB port or something.
• PCB Color - I always spend the extra for a cooler colour, but green is the cheapest.
• Surface Finish - this what the pads and such will be on the final board. I always splash the extra dollar or so for lead free finish with lead being a bit toxic and all. ENIG is a more durable finish that is good for connectors and things. I've only used it on one PCB I've ordered before which plugs in, but it's more expensive.

Finally, we've got a few other options. I tend to turn on "Confirm Production file" which is where an engineer will send you the production file to check, and I often change the "Mark on PCB" to "Order Number (Specify Position)" which is where you can add a position on the board where you'd like them to put your order number so it's not anywhere that would affect the aesthetics of the board (make sure to check with the manufacturers website on how to specify the location), although the barcode option is new since I last ordered, so I'd probably use that as it'll be less intrusive. Remove mark has no order number at all, but costs extra. All of the other options can stay as they are, and would only be used in special use cases.

From there you can go and complete your order. For reference, this board would cost $3.20 with around $8 for the cheapest shipping option which is pretty reasonable. You can also add on additional services like assembly where they'll actually solder some or all of the components onto your board. I'd love to try this one day, but I've not had any projects that it'd be useful for yet.

Wrapping Up

Hopefully this quick crash course in PCB design has been useful and inspiring. I had always thought it was quite intimidating until I went to a talk on how someone designed conference PCB badges with some other PCB design software, and it's super cool to build something on your computer and eventually have a physical PCB! Until next time...