EMI/EMC failures destroy otherwise well-engineered products through late-stage discovery. Between 40% and 60% of products fail initial EMC testing, creating expensive redesigns, project delays, and missed market windows. Electronic devices operate within increasingly dense electromagnetic environments, making electromagnetic compatibility a fundamental engineering requirement rather than an optional consideration.
This article is our take on one of the modern-day sins of electronic product engineering – ignoring EMI/EMC considerations from the start of the design process.
What is EMI/EMC and why it matters
Electromagnetic Interference (EMI) describes unwanted electromagnetic emissions that disrupt electronic device operation. These emissions propagate through air radiation or conduct through power lines and interconnects. Electromagnetic Compatibility (EMC) defines a device's ability to function correctly within its electromagnetic environment while avoiding intolerable interference with other equipment.
This distinction carries significant weight because modern electronics function within interconnected systems. Device interconnectivity increases interference probability, signal distortion likelihood, and equipment malfunction risks. Minor electromagnetic noise can trigger critical failures in sensitive applications, particularly medical equipment where interference affects life-sustaining devices.
EMC compliance represents legal necessity, not engineering preference. Regulatory bodies mandate EMC compliance before product marketing authorization. The FCC establishes electromagnetic emission limits within the United States, while ISO and IEC organizations provide acceptable EMI testing standards internationally.
Consequences of late-stage interference issues
EMI/EMC problems discovered during late development stages create project-wide complications. Design changes become exponentially more expensive as products approach production readiness—early screening tests cost substantially less than complete EMC certification procedures. Failed testing cycles represent direct testing expenses, lost market timing, and competitive positioning disadvantages.
Late-stage EMI corrections require expensive hardware modifications. PCB redesigns, additional shielding components, and filtering elements increase both cost and complexity. These modifications frequently compromise original design specifications, forcing performance, size, or power consumption trade-offs.
Financial consequences prove substantial. Single formal EMC testing rounds cost approximately $10,000 within the U.S.. Product failures necessitate expensive redesigns and repeated testing cycles. Combined delay costs, redesign expenses, and additional testing frequently reach six-figure totals for complex products.
Late EMI discoveries damage customer relationships and brand reputation beyond direct costs. Products passing initial testing but exhibiting field failures due to unforeseen electromagnetic interference create warranty claims, product returns, and customer confidence erosion.
Best practices for early EMI/EMC compliance
EMC considerations integrated from project initiation dramatically improve first-pass compliance success rates. The fundamental approach requires simple execution:
Best practices for early EMI/EMC compliance
"Consider EMC in the earliest stages of the design process. It can save considerable time and help prevent time-consuming PCB redesigns".
Early-stage pre-compliance testing identifies vulnerabilities while design changes remain cost-effective. Radiated emission screening during prototype phases pinpoints problem areas before production tooling finalizes designs. Spectrum analyzers and near-field probes identify EMI sources and evaluate design effectiveness.
Strategic PCB layout practices provide EMC compliance foundations:
- Minimize trace lengths to prevent unintentional antenna formation
- Avoid signal routing over split reference planes
- Implement solid filled reference planes separating noisy signals from sensitive circuits
- Execute proper grounding—the most common EMC testing failure cause
System-level EMC requires specific cabling attention. Circuit ground connections to chassis at cable entry/exit points require very low impedance implementation. This approach prevents unintended radiation and optimizes IO-signal filter effectiveness against external interference.
EMC functions as a system-wide engineering discipline rather than component-level consideration. Product development timeline planning should allocate specific phases for EMC design reviews and pre-compliance testing before production tooling commitment.
Conclusion
The transition from costly "design, test and fix" cycles to "designing for compliance" from project start eliminates this engineering oversight and creates products that perform reliably within real-world electromagnetic environments. At Embien, we follow a EMI/EMC first design methodology that eliminates these risks and ensure the product is ready for pre-compliance even in its first iteration. Feel free to reach out to our hardware engineering team to help get your product certified for EMI/EMC.
