Issue link: https://iconnect007.uberflip.com/i/1537388
30 DESIGN007 MAGAZINE I JULY 2025 » Verify that your constraints match up to meet your design requirements and expectations. • Use your EDA tools: » Let your software do the heavy lifting. Today's EDA tools are more powerful than ever. Use them to your advantage. » Set up design rule checking (DRC). Indus- try best practice: do NOT turn the DRC off during the layout stage and then run a DRC after the fact, compelling you to go back and address all the flagged errors. » Don't ignore those DRC errors (they're try- ing to help!). Use the DRC to enable a cor- rect-by-construction approach. • Think about the performance of the PCB (i.e., SI/EMI/PI/EMC/thermal): » Follow industry best practices. » Keep sensitive traces short. » Allow for appropriate spacing. » Route all traces adjacent to their respec- tive reference plane. » Pay attention to differential pairs. » Watch out for crosstalk. » Know where the heat is being generated and resides in your design, and how to mitigate it. » Account for critical attributes such as imped- ance requirements, trace length matching/ tuning, and trace current carrying capacity. » Simulation and analysis must not be skipped! Common mistakes to avoid: • Making rules too strict. Over-constraining and endless quests for perfection are enemies of getting the job done. • Ignoring what your manufacturer can actually do (their capabilities). • Failure to address all three competing per- spectives in PCB design: solvability, per- formance, and manufacturability, AKA the designer triangle. • Not talking/collaborating with your manufacturer(s) early enough in the process. • Creating a "garbage" design and tossing it over the wall to manufacturing and hoping for gold in return. • Trying to wing it without proper planning. The Bottom Line Setting up PCB design constraints isn't the most exciting part of design, but it's like brushing your teeth—a little prevention goes a long way. Take the time to set them up right, and you'll save yourself from pulling your hair out later. Many of today's EDA tools have the ability to create and retain constraint templates for reuse. Reuse saves time and money. Remember, keep it realistic and don't over con- strain your design, or you'll end up in a gridlock sit- uation. Collaborate with your manufacturer as early as possible and throughout the design process. Communication is key; therefore, you cannot com- municate enough. Document your decisions for traceability and to understand why particular deci- sions are made. Use your EDA tools to your advan- tage by working smart, not hard. Lastly, don't over- think it. If you're ever in doubt, it's better to ask ques- tions early than to get nasty surprises when you are hit with TQs causing work stoppages, or worse when your board comes back from manufacturing. Believe me, your manufacturer has seen it all. They are a wealth of knowledge, a great resource to tap into, and are usually happy to help. There you have it. Get these basics right, and you'll be well on your way to creating PCBs that not only work great but can actually be manufac- tured without breaking the bank. DESIGN007 Stephen V. Chavez is principal technical product marketing manager with Siemens EDA and chair of PCEA. " " Keep it realistic and don't over constrain your design, or you'll end up in a gridlock situation.