EMI Bites: Why Your PCB Stackup Needs to Be Symmetrical
EMI Bites: Why Your PCB Stackup Needs to Be Symmetrical
When designing a multilayer PCB, symmetry is necessary.
Think of your stackup as two halves of a mirror—balanced top to bottom.
Why this matters:
- Asymmetrical stackups lead to uneven thermal expansion.
- This can cause the board to warp when it heats up during operation or reflow.
- Warping puts mechanical stress on solder joints, risking component detachment.
- Uneven layer structure can also affect impedance and EMI performance.
Key Insight:
A well-balanced stackup protects both your signal integrity and your hardware reliability.
How to design a solid stackup:
- Place signal layers (or power) adjacent to return reference planes (RRP).
- Mirror the structure vertically to match signal and plane layers top-to-bottom.
- Balance the copper distribution and dielectric thickness across the stack.
- Review the thermal behavior of the stackup with your PCB manufacturer before finalizing.
- Don't be shy to simulate when needed ;)
To electromagnetic enlightenment,
- Dario
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