Before exporting your PCB design for fabrication, you **must **verify the design and fix any errors. Time invested verifying your design before manufacturing will make the assembly and testing process significantly easier.

What are best practices for the design of PCBs?

• Designing PCBs for Debugging - (First Board Spins) video from Casey Petersen
• Fundamentals of Layout Out PC Boards from Jack Ardizzoni of Analog Devices
• Printed Circuit Board (PCB) Design Issues from Analog Devices
• PCB Design of Switch Mode Power Supplies (SMPS or Switchers) video from Casey Petersen
• A Practical Guide to High-Speed Printed Circuit Board Layout from Jack Ardizzoni of Analog Devices
• High Speed System Applications: PC Board Layout and Design Tools from Analog Devices

General

• All components have footprints
• Bypass/decoupling capacitors for voltage regulators are placed as physically close as possible to the regulators
• Bypass/decoupling capacitors for ICs are placed as physically close as possible to each IC’s power and ground pins (see example of good layout, Figure 1)
• Power and ground traces are at least 40 mil wide and were sized using a trace width calculator
• Board space is allocated for mechanical constraints (e.g., PCB mounting holes, heat sinks, connectors)
• The top and bottom copper layers are labeled in text “top”, “bottom”, and “group name”

Figure 1: Example of good bypass capacitor placement

Vias

• Minimize the number of vias in your design. Vias reduce the reliability of your system.
• No vias under components (particularly ICs)

Additional Considerations

• Consider how your components will be mounted when routing traces. For example, if you have a through-hole connector on the top of your board, it’s better to route the traces for it on the bottom layer.
• Make the board outline in copper
• Make sure that the size of your board will fit inside your product enclosure
• Do NOT use the autorouter. Use manual routing to simplify the board design. Simple design = easier debugging.
• When using surface mount components, size 0805 resistors and capacitors (or larger) are easier to work with
• Through-hole connectors are mechanically stronger than surface-mount connectors
• Avoid right angles (90 degrees) in traces. Instead, “curve” the trace with a 45 degree angle around a corner
• Fill some extra space on your board with several 0.1" spaced test points to allow for easier modifications
• If your system uses in-system programming (ISP), place the ISP connector as physically close to the microcontroller as possible