Ask Me Anything about PCB Design Constraints

Participate in our next Ask Me Anything about design constraints where you can ask us questions on:

  • Best practices for managing design constraints
  • Tips for optimizing layout and routing
  • Strategies for mitigating common design issues
  • And much more!

:speech_balloon: Question submission window: Through June 26th

how to identify which signal should have which constraints?

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Do you consider that it is good practice to have default templated design constraints? Should the design constraints be evaluated from scratch for each project, for each manufacturer?

Thank you

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It depends a lot on your workstyle. Some people like to ferret out every question and answer before committing the design to paper. Others solve things and make choices as they go along. I would certainly say that some basic items, such as some preferred vias and holes sizes, min and max trace details, and clearances, are good to have already waiting. But items like net clearances or lengths will vary from board to board so there can be no template.

Well, by FAR the best practice is to ask the circuit designer. If you are knowledgeable you can look at IC data sheets and such, figure out what things are fast signals (probably), what things are sensitive (maybe), and hope for the best. Or, you can check with the person who designed the circuit, knows how it works, knows what they are going to use it for, knows how they’re going to use it, knows what other relevant conditions are worth noting (other nearby equipment, environmental behavior/limits, power supply conditions/limits, appropriate regulatory issues, ultimate customers requirements and tolerances, cost restraints, life expectancy, and any inter-operability conditions that exist).