The first step to making a Printed Circuit Board (PCB) is to make a diagram, which is also called the PCB schematic. It is this diagram that helps point you in the right direction on what to do and where it is to be added to the circuit board.
In this article, we explain some of the steps you must take to make this schematic and to convert the same to a PCB layout.
What is a PCB Circuit Diagram?
Also called the PCB schematic, it is a graphical representation of the components needed to make the circuit board. The schematic also points out where these components are to be placed on the board, as well as every other aspect of interconnecting the board’s electrical circuit design.
What Makes up the PCB Schematic?
Since it is more of a graphical representation of the circuit board components, the schematic’s properties also align with that. Ideally, you will find the references, such as the symbols and labels associated with the components to be used on the circuit board.
The references also cover other elements that bolster the circuit’s functionality. These include but are not limited to:
- Reference indicators
- Connectors and;
- Ground connections
How to Get Started
To start designing your circuit diagram, a couple of things need to be pointed out. Before now, it is common to make manual designs of the diagrams, especially if you are following the DIY procedure.
However, for the purpose of this article, we are concentrating on the modern method of PCB schematic, which has to do with using a design tool.
The second point to note is that the Printed Circuit Board (PCB) usually has the conductive pathways etched with copper or some other conductive material. However, when it is time to manufacture or design the board, these copper traces are etched off to make the way for clear mounting of the traces.
How to Make the PCB Schematic
Let us start by talking about the steps to take when making the circuit diagram. Follow these steps and you will be on your way to getting the component structure accurately.
1. Special Consideration for Complex Circuits
You need to make a special consideration for the complex circuits. For this type of PCBs, it is best to allow the signals to flow from the left to the right, whereby the input and controls should be on the left, while the output will be on the right.
2. Reference Indicator Mastery
It is crucial to understand the major reference indicators for the PCB. That should go a long way to help you know what and where to put the indicators on the diagram.
Examples of the PCB reference indicators are:
- Integrated Circuit (IC)
- Circuit Breaker (CB)
- Attenuator (ATT)
- Diode (D)
- Variable Resistor (VR) and;
- Resistor (R)
3. The Choice of a PCB Schematic Tool
There are lots of schematic tools or software you can use to make the circuit diagram for your PCB. EasyEDA is one of the most popular, but there are also others like KiCad, DipTrace, DesignSpark and EAGLE.
4. Get Started with the PCB Designing Software
We will now give you a rundown of the steps to take to ensure that your Printed Circuit Board (PCB)’s circuit diagram is designed and converted to the layout in good time.
- Create a New Project: sign up with your email address on EasyEDA or any other circuit board designing tool. Create a new project to get started.
- Use the Library: most of this software have a dedicated user generated library, from where you can pick the common symbols and reference designators for the PCB components.
- Match the Components: for each of the symbols or reference designators in the libraries, there is a corresponding footprint. The footprint indicates the placement method and the size of the components. You can always make a manual change of these footprints to match the circuit diagram you want.
- Draw the Wires: this involves making the wiring pathway for the circuit board. It is also better to assign labels to the wires for easy identification.
5. Edit the PCB Schematic
The major aspect of the circuit diagram creation has been completed. Now, you have to edit the schematic. Start by importing it into the dedicated PCB editor.
On EasyEDA, navigate to the schematic editor and click on the “Convert Project to PCB” button.
The following are the next steps to take:
- Footprint Population: the footprints initially assigned to the components will now be populated or automatically transferred to the PCB editor.
- Start Routing with Ratsnet Lines: also called the ratlines, the ratsnet lines refer to the virtual wires (represented or marked out by thin blue lines) that indicate the electrical connections that haven’t been converted into the physical connections. The goal is to use the pathway indicated by the thin blue lines to find out where the traces, vias and copper pours are to be created in the PCB schematic.
- Routing Options: when it comes to routing the traces and other important electrical connections, the choice always boils down to the manual and the automated approaches. EasyEDA and some other PCB designing tools have an auto-router feature that handles the routing. However, it may be better to make a manual routing of the electrical connections, especially if the circuit components have been found to work better in some other locations than specified in the footprints. The manual option is also a better option for complex/complicated circuit boards.
6. Creating the PCB Stackup
Now that the traces and other electrical connections have been routed, your concentration should now turn to creating the stackup of the Printed Circuit Board (PCB).
A lot of processes go into these and they include:
- Board Dimensions: this specifies the dimensions or how spacious the board would be. the PCB dimensions also need to align with the number of components, and the spaces on the board. The number of layers and where the layers and materials are to be positioned inside the board are also worth considering.
- Component Arrangement: click on the board outline and continue adjust it until all the components needed for the schematic are added. Take note that an excellent spacing is to be maintained to ensure that the PCB meets the design rules.
- Schematic Consistency: another factor to consider here is the consistency of the final design to the footprint or initial outline of the board. It is imperative to maintain a consistency between the layout of the PCB and the schematic.
7. Testing the PCB Layout
Before the Printed Circuit Board (PCB) layout is sent to the manufacturer for the final production, it has to be tested across different facets. Generally called the Design Rule Check (DRC), it is a dedicated error-detection test to check the PCB layout for errors.
These are some of the things you need to know about the DRC:
- Design Rule Compliance: the design rule is a circuit board manufacturing standard and limitation placed on each board to make sure it meets all criteria for final production. Thus, what the Design Rule Check (DRC) does is to check the actualized PCB layout against the design rule to be sure it followed what was specified there. Examples of these design rules include drill diameter (minimum), trace spacing and trace width.
- Component Overlapping: the DRC pays keen attention to the overlapping tendencies of the components, as well as to the closest routing of the traces. Adequate spacing is required for both scenarios.
- “DRC Errors” Notifications: by using the Design Manager tool in your PCB CAD tool, you will find out what type of errors the layout has. These errors are generally marked as “DRC Errors.” Once you click on this DRC Errors folder, you should see the different problems or errors the PCB layout has. On clicking each of the errors, you should have an overview of the affected electrical components or trace.
What Next after PCB Layout?
Now that the layout for your circuit board has been derived from the circuit diagram, you have one more step to get the job done. It is the time to manufacture the board. Your best option is to use the services of a PCB manufacturer.
To place your order, follow these steps:
Download the Gerber Files
The PCB CAD tool you used may have the option to take your orders for manufacturing. But if you choose to send the specifics to a different manufacturer, it is imperative that you download the Gerber Files that contains a pictorial representation of the patterns for making the PCB layout.
Sign up for an Account
Most PCB manufacturers require you to create an account for an excellent tracking of your order. You can use your email address or sign in with your socials if that option is enabled.
Enter the Board’s Specifics
The specifics we mean here include the dimensions, number of layers and the thickness of the circuit board. You also want to specify copper weight, PCB/silk layer color and the number of PCBs you want to have manufactured.
With lots of options out there, you may be unsure of how to pick the best PCB designing software. Not to worry because we have made a list of some of the best designing tools, and this includes EasyEDA, KiCad and EAGLE.
For the best results when converting your circuit diagrams to PCB layout for final production, make sure you take the design optimization seriously. The best ways to optimize the PCB layout include designing the rest of the circuit board around the locations of the components and maintaining at least 45-degree bendability of the copper traces, as that helps in shortening the electrical pathway between the electrical components on the board.