Designing a PCB with DEX > Parts > Don't Trust Part Libraries

The phrase "Don't Trust Part Libraries" is a common mantra among experienced electronics designers, especially those involved in PCB (printed circuit board) design. The reason behind this cautionary phrase is that relying solely on pre-existing part libraries without verification can lead to costly mistakes. Here's why designers advocate for this cautious approach:

•Mistakes in Libraries: Even the best libraries can contain errors. This could be a wrong footprint, incorrect pin assignment, or any number of other possible issues.

•Outdated Libraries: Components get updated by manufacturers, and libraries might not reflect the most recent version.

•Variability in Standards: Different manufacturers might have slightly different recommendations for land patterns or footprints for the same component.

•Specific Requirements: A generic footprint from a library might not meet specific needs, such as a particular soldering process or thermal requirements.

•Lack of Comprehensive Data: Some libraries might provide footprints but lack schematic symbols or 3D models.

•Consistency: When working on a team or on multiple projects, having consistent naming conventions and organization can be crucial. Relying on external libraries can introduce inconsistency.

•Verification: Even if a part library is correct, it's a good practice to verify the footprint and schematic symbol against the component's data-sheet. This step ensures that the component will fit correctly on the PCB and function as expected in the circuit.

•What to Do Instead?

•Verify Everything: If you decide to use a part from a library, always cross-check it against the manufacturer's data-sheet.

•Build Your Library: Over time, create and maintain a personal or company-specific library of components that have been verified and used in successful projects.

•Use Library Tools: Some advanced PCB design software offers tools that can automate the process of checking and verifying footprints and schematic symbols.

•Collaboration: If working in a team, collaborate and have peer reviews of new library components. Two eyes are always better than one.

•Stay Organized: As you add to your library, keep it organized. Proper naming conventions, categories, and clear version control can save a lot of headaches in the long run.

•Backup and Version Control: Ensure that your libraries are regularly backed up and that there's a system in place for version control.

In conclusion, while existing part libraries can save time and provide a valuable starting point, it's essential always to verify each part's details. This approach ensures the reliability and functionality of the final PCB design.