Lessons Learned

This chapter summarizes the key concepts, definitions, and lessons learned throughout our exploration of PCB design using KiCad, along with important terminology and best practices.

Key Topics Covered

1. Introduction to KiCad

KiCad is a suite of open-source software tools used to create printed circuit boards (PCBs). It offers a comprehensive platform for managing all aspects of PCB design, from schematics to layout, component management, and final manufacturing output files.

  • Applications in KiCad:
    • Eeschema: Schematic Editor
    • PCBnew: PCB Layout Editor
    • 3D Viewer: Visualizes the final PCB in 3D
    • Gerber Viewer: Used to inspect Gerber files before sending them to manufacturing

2. PCB Design Workflow

The PCB design workflow in KiCad consists of two major steps:

  • Schematic Design (Eeschema): The process of creating a schematic that defines the electrical connections between components.
  • PCB Layout Design (PCBnew): Translating the schematic into a physical layout of the PCB, including the placement of components and routing of traces.

3. Component Libraries

In KiCad, components are represented by two key elements:

  • Symbols: Represent the functional aspects of components in the schematic (e.g., resistors, capacitors).
  • Footprints: Represent the physical layout of components on the PCB, including pad sizes and positions.

KiCad comes with extensive symbol and footprint libraries, but custom components can also be created using the Symbol Editor and Footprint Editor.

4. Navigating KiCad's Tools

KiCad provides an intuitive interface with toolbars for quick access to commonly used features, and mouse navigation for zooming and panning within the workspace. It is highly customizable, allowing users to configure layer visibility, object selection filters, and interface settings based on individual needs.

5. Project Management

KiCad projects are composed of multiple files:

  • .pro: The project file that holds overall project information.
  • .kicad_pcb: Contains layout information for the PCB.
  • .kicad_sch: Contains schematic information. All of these files are stored in plain text format, making them easily accessible and version-controlled using tools like Git.

6. Manufacturing and Gerber Files

Once the PCB layout is complete, the design is exported as Gerber files, the industry-standard format for PCB manufacturing. Each Gerber file represents a specific layer of the PCB (e.g., top copper, bottom silkscreen), and a drill file provides information about the holes and vias.

Gerber files are loaded into a manufacturer’s system to fabricate the board. Some manufacturers, such as Oshpark, also support direct uploads of KiCad PCB files.

Important Definitions and Abbreviations

PCB (Printed Circuit Board)

A physical board that electrically connects and mechanically supports electronic components using conductive traces, pads, and other features etched from copper sheets laminated onto a non-conductive substrate.

KiCad

An open-source software suite used for electronic design automation (EDA), primarily for designing and producing PCBs. It includes tools for schematic capture, PCB layout, 3D visualization, and Gerber file generation.

Eeschema

KiCad’s Schematic Editor, used to create the schematic diagrams that represent the electrical connections between components in a circuit.

PCBnew

KiCad’s PCB Layout Editor, where the physical layout of the PCB is designed, components are placed, and traces are routed.

Gerber Files

A set of files generated from the PCB layout that contain all the data required for PCB manufacturing. Each file represents a different layer or aspect of the PCB (e.g., copper layers, silkscreen, solder mask).

BOM (Bill of Materials)

A document that lists all components used in the PCB design, including part numbers, quantities, and specifications.

Footprint

The physical representation of a component on the PCB, detailing the size and location of the pads where the component will be soldered.

Symbol

A graphical representation of an electronic component used in the schematic to illustrate its function and connections.

ERC (Electrical Rules Check)

A tool in the Schematic Editor that checks for errors such as unconnected pins, conflicting signals, or other electrical design issues.

DRC (Design Rules Check)

A tool in the PCB Layout Editor that ensures the PCB layout adheres to design constraints, such as minimum trace widths and spacing between components.

Via

A small conductive hole in a PCB that allows traces to connect between different layers.

SMD (Surface-Mount Device)

An electronic component that is mounted directly onto the surface of the PCB, as opposed to through-hole components, which are mounted using leads that pass through holes in the PCB.

Best Practices and Insights

1. Iterative Design Process

PCB design is an iterative process that requires refinement at every stage, from schematic capture to layout and manufacturing. Running checks like ERC and DRC regularly can help catch errors early in the design process.

2. Understand Your Manufacturer’s Capabilities

As a PCB designer, it’s essential to understand the manufacturing capabilities of your chosen fabrication partner. This includes knowing minimum trace widths, via sizes, and layer options. Manufacturers like PCBWay and Oshpark provide user-friendly interfaces for uploading designs and configuring specifications.

3. Use Component Libraries Efficiently

KiCad offers extensive symbol and footprint libraries, but for specialized components, you may need to create your own. Take advantage of the Symbol Editor and Footprint Editor to manage custom parts and ensure they fit your design requirements.

4. Layer Management

Managing layers effectively in the PCB Layout Editor is crucial for reducing clutter and ensuring accuracy during the design phase. KiCad’s Appearance Pane allows you to toggle layers on and off, making it easier to focus on specific parts of the board, such as the copper or silkscreen layers.

5. 3D Visualization

The 3D Viewer is a powerful tool in KiCad that allows you to visualize your PCB before manufacturing. This can help you catch potential design issues, such as component placement errors, and ensure the board looks as expected once populated with components.

Conclusion

The lessons learned throughout this process have given us a comprehensive understanding of KiCad’s powerful capabilities for PCB design. From the early stages of schematic capture to the final layout and manufacturing stages, KiCad provides all the tools needed to design both simple and complex PCBs. By following best practices, understanding key terminology, and utilizing the resources KiCad provides, you can confidently create professional-quality PCBs for any project.