PCB EMC Design Kit
A field-theory-first reference for designing boards that pass EMC testing. Covers golden rules, checklist, self-assessment, stackup builder, failure diagnostic, and flashcards.
10 Golden Rules
Click any rule to expand the field-theory explanation.
Return Current Behaviour by Frequency
| Frequency Range | Return Path Behaviour | Governed By | EMC Risk |
|---|---|---|---|
| DC – 1 kHz | Spreads across entire RRP — fully distributed, wide current sheet | Least resistance (R) | Low |
| 1 kHz – 10 MHz | Transitional — spreading narrows progressively toward trace | Mixed R + jωL | Moderate |
| > 10 MHz | Tightly coupled directly beneath trace (skin effect) — mirror image of signal | Least inductance (L) | High if RRP absent |
| Edge rate < 1 ns | Effective frequency > 350 MHz — via stubs become antennas, dielectric loss rises | fₕ ≈ 0.35 / tᵣ | Critical |
Key Terminology
Stackup Builder
100%
EMC Score
EMC Failure Diagnostic
Flashcards
1 / 8
TERM
Tap card to reveal
DEFINITION
0
Seen
0
Got it
0
Review
Fresu Electronics · fresuelectronics.com
PCB EMC Design Kit
Quick Reference · 2026
10 Golden Rules
Return Current by Frequency
| Range | Return Path | Governed By | Risk |
|---|---|---|---|
| DC–1 kHz | Spreads across entire RRP | Least R | Low |
| 1k–10 MHz | Transitional, narrows toward trace | R + jωL | Moderate |
| >10 MHz | Directly beneath trace (skin effect) | Least L | High |
| tᵣ <1 ns | f >350 MHz, via stubs critical | 0.35/tᵣ | Critical |
Key Terminology