Selecting the right stackup for a Printed Circuit Board is the strongest predictor of whether a design will fail or pass an EMC test. That’s why it’s always the first thing I check when performing an EMI review for a client. The stackup immediately shows me how well the designer understands signal propagation and field behavior in the dielectric. It also reveals their grasp of energy containment, channeling, and transfer. These are the foundations that decide whether EMI problems are likely to appear later on. If the foundations are wrong, everything else will collapse. At that point, layout tweaks, component placement, filters, and simulations can only have a marginal effect. It’s like eating junk food all week and then expecting an apple on Sunday to make you lose weight overnight. It doesn’t work that way. This is often the tough part about EMI, and one that many project managers (and even some designers) don’t like to face. Because if the stackup is wrong, the budget is at risk, especially if fixing it requires adding layers or a full stackup redesign. That’s why it’s essential to set it correctly from the start, instead of choosing it only based on cost and ignoring the long-term impact on project success. But this doesn’t mean you need to overthink it. The principles for choosing the right stackup are actually simple, straightforward, and intuitive, once you understand the reasons behind them. To electromagnetic enlightenment, Dario P.S. If you’re still unsure how to put these concepts into practice and want to master EMI control, join my free crash course here: fresuelectronics.com *Qualification apply.