As PCB designers, our job is only halfway done once we sketch out our schematics. We still have the somewhat technical task of actually designing a functional board. This is where great Printed Circuit Board software comes in handy. We can seamlessly create, edit, and send files in-between departments without having to stand in line at the photocopier.
But how do we take a two-dimensional schematic sketch into a PCB Gerber layout ready to send off to a prototyping board house? With Altium Designer, it won’t take you more than an hour to get the hang of the schematic to PCB layout process.
Previously, we focused on making a simple active amplifier using the TI LM386 op amp. We’ll be continuing on from the end schematic of that tutorial, then walking through the process to convert it into a proper PCB Gerber file.
The final version of our file will look something like this:
A preview of what our final PCB Gerber file will look like.
The Schematic for our PCB Design
Below is the schematic we’ll base our PCB design with one minor correction. The speaker designator has been updated to SP1. It’s always important to document changes to designs and even more important when you’re documenting changes to designs intended for large teams, organizations, and audiences.
The ending amp schematic we will be working to make a PCB from.
Making a New PCB Project in Altium Designer
After you have your finalized schematic, you’ll head to the left-hand panel, right-click the PCB project file and navigate to ‘Add New to Project’ > ‘PCB.’ You’ll want to be sure to save any last edits in the schematic before continuing with making the new PCB file.
After opening the new Printed Circuit Board, you should see a blank PCB design document opened up:
A blank PCB project
Once here, you will need to save the Printed Circuit Board document into your project folder going to ‘File’ > ‘Save.’
At this point, I usually like to turn off the ‘automatic room generator’ by navigating to ‘Project’ > ‘Project Options’ > ‘Class Generation’ then unselect ‘Generate Rooms’ as shown below. This will get rid of the predefined red box you might see after the next step if you left this on.
Options of how to adjust your PCB project to an optimal format.
Import Schematic Components
After the PCB manufacturer project is saved, navigate to ‘Design’ > ‘Import Changes from [PCB Project].prjPCB.’ you’ll see this screen:
How to import schematic components into your blank PCB document.
The screen above essentially represents each change or discrepancy that the program detects as labeled as an Engineering Change Order (ECO), which should be familiar to some.
Without spending a majority of time in the ECO, you can simply select ‘Execute Changes’, then ‘Close.’
Each of your components will be placed on the document (off the circuit board to the right) as shown below:
Where your imported components are imported.
From here, you can simply drag your selection box over the entire collection of components and drag them to anywhere in your circuit board space. As with any design, you’ll be changing the placement and adjusting as necessary through our process so the initial placement isn’t entirely crucial.
You can start rearranging each component following the routing guidelines as best as you can until you reach a placement configuration you think will work.
A feature that saved me a lot of time is finding out that when you left-click and hold to move, you can hit the spacebar which will rotate the part 90 degrees giving you more orientations to place from. Furthermore, something to take note of is when you are moving components around, the GND pins will sometimes jump from one GND pin to another. Take note if your GND pin alignment is critical. In the case of this guide, you will simply roll with it.
I’ve already taken a few minutes and found a decent arrangement that will work for our purposes:
A PCB component placement arrangement that may work for your purposes.
Changing Board Size
To change the board size (the black background) to match what you have above, navigate to ‘View’ > ‘Board Planning Mode’. Once you see a green board, navigate to ‘Design’ > ‘Redefine Board Shape.’
You’ll be able to trace out a board of any size around the above components.
The circuit board corner defaults will be set to a 45-degree angle. To change this, press ‘Shift’ + ‘Spacebar’ to toggle through the various options. I usually stick to 90-degrees.
Set the Origin
Manufacturers will ideally like an accurate reflection of the origin. Since you have modified the component locations as well as the board size, it is good practice to place an origin point at an intuitive location.
Since you might usually work in cartesian domains, I like to place my origins on the bottom-left of the board. This gives everyone a nice positive x and y value when extrapolating from the design.
To set the origin, simply navigate to ‘Edit’ > ‘Origin’ > ‘Set’ and place it wherever your heart desires.
Don’t Forget Routing
After you define the board size, and this step can be done after the trace routing as well, you can begin to trace your routing from pin to pin. This is one of my favorite parts, personally.
Be sure to switch back to the 2D Layout Mode (in ‘View’ > ‘2D Layout Mode’) before beginning this step, it will help you immensely.
To establish any trace ground rules, such as default trace width, annular ring requirements, etc., navigate to ‘Design’ > ‘Rules’ and create, delete, or modify any rules you wish to implement upon beginning your tracing process. For the purposes of this tutorial, you’ll leave all rules as they are.
Navigate to the upper toolbar and select ‘Interactively Route Connections’ or ‘Ctlr + W’. From here, simply hover over any pin and click to begin the trace. Each pin you select will guide you to its corresponding pin allowing you to focus on making cool looking traces.
Just as in the board boundary creation, if you want to toggle through various corner shapes press ‘Shift’ + ‘Spacebar.’ I like to leave it on the 45-degree corner option since it’s the one that most closely resembles a Tron-like configuration.
The end routing I came up with is illustrated below:
PCB components with routing between them.
Adding Vias to Your PCB Project
Since this example requires input from an audio source, you’ll need to add in a few very basic ports for a source to solder to. Be sure to understand that the battery section of this circuit could also be configured differently, but that’s for another time.
Adding in a few vias will give our users an option to solder their inputs sources. To add a via to your board, navigate to the upper toolbar and select ‘Place Via’ and simply place it wherever you choose.
You may have to designate a ‘Net’ to each via before a trace is allowed to connect. To do this, double-click the corresponding via, and under ‘Net’ select which net to connect to.
In our example, I placed them in a convenient location for our user to access and added traces directly to them:
Now the PCB is routed and has necessary vias and nets.
Creating a Gerber File
With components placed, routed, and vias added, you are essentially ready for a Gerber file to be produced. After saving each document, you can navigate to ‘File’ > ‘Fabrication Outputs’ > ‘Gerber Files.’
Select the setup options you want as well as the layers to include and then select ‘OK.’
And, as promised, the final PCB Gerber file.
A PCB Emerges
After these steps are completed, you have a PCB Gerber file good enough for virtually any manufacturer to produce a prototype out of. If you were to become proficient enough, you would readily be able to go from schematic design to prototype in-hand in a matter of days.
As always, there can be a plethora of improvements but this will cover the bare bones of creating a PCB from a schematic to an ending Gerber file.
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