Q: Components with high current draw are less likely to generate EMC issues. True or false?
A: False.
That should be obvious—high current can often correlate with more EMC issues.
Q: Can reducing trace lengths help minimize EMI issues?
A: Yes, it can help.
It’s not a silver bullet, but shorter traces generally improve EMI performance.
Q: Does reducing PCB size help with EMC performance?
A: Yes.
Smaller PCBs mean shorter traces and better containment of energy, assuming the operating frequency remains the same.
Q: If you switch from 5 mil to 2 mil trace/space technology and keep PCB cost constant, does the smaller board size improve EMC?
A: Yes, if frequency remains the same.
Tighter layout = better energy control and reduced EMI.
Q: Does using a thicker PCB have any impact on EMC performance?
A: Yes, and this is often underestimated.
Thicker boards increase the distance between signal traces and reference planes, which can worsen EMC performance.
Q: Is there a general rule for trace spacing to minimize crosstalk?
A: Yes.
Keep traces spaced at least 3x the trace width apart.
But in high-density PCBs, this isn’t always practical.
Q: So what’s the workaround when space is limited?
A: Move traces closer to the ground plane.
By reducing the dielectric thickness (bringing traces closer to the plane), you confine the energy and reduce EMI and crosstalk.
Q: So thinner PCBs are better for EMC?
A: Often, yes.
Less separation between signal and ground means better performance. But you must also consider stack-up design.
Q: What’s important in stack-up design for EMC?
A: Coupling signal layers to reference planes.
For example, on a 4-layer board, the signal layers should be close enough to the ground plane to serve as effective references. Don’t assume a distant layer can function as a reference.
Rule of thumb (validated):
The more separation you have between a signal layer and its reference plane, the worse your EMC performance will be.
Signal-ground proximity is crucial. Design your stack-up accordingly.
Watch Trace Talks EP 8 with Ignacio de Mendizábal.