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As electronic devices become faster and more compact, susceptibility to electromagnetic interference (EMI) increases. Effective EMI control is not only about material selection—it requires a comprehensive strategy involving grounding, enclosure-level shielding, and cable shielding. In this post, we’ll explore best practices for each of these areas to help engineers build reliable, compliant, and high-performance systems.
1. Grounding Best Practices
Grounding provides a low-impedance path for unwanted noise and is the foundation of EMI control. Poor grounding can result in voltage fluctuations, crosstalk, or even complete device failure.
Tips for effective grounding:
• Use a Single-Point or Star Ground: Prevents ground loops that cause interference.• Ground Planes Over Traces: Dedicated planes reduce impedance and stabilize reference signals.
• Short, Wide Connections: Minimize inductance by keeping ground connections short and using wider
traces.
• Separate Analog and Digital Grounds: Join at a single point to reduce noise coupling between
sensitive circuits.
• Bond Shields to Ground at One End: Especially for cables, this prevents circulating currents while still
draining EMI.
2. Enclosure-Level Shielding
Enclosures act as the first line of defense against external EMI and contain emissions from within. The effectiveness depends on both material choice and mechanical design.
Best practices:
• Conductive Materials: Aluminum, copper, or conductive-coated plastics provide strong shielding
effectiveness.
• Continuous Ground Contact: Ensure enclosure seams, doors, and panels maintain electrical contact
(use conductive gaskets or finger stock).
• Avoid Gaps & Leaks: Even small openings can act as antennas; use honeycomb vents or filtered
connectors.
• Bonding Strategy: Enclosures should be electrically bonded to the system ground for maximum
protection.
• Surface Treatments: Nickel or tin coatings improve corrosion resistance while maintaining
conductivity.
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3. Cable Shielding
Cables are often the largest EMI antennas in a system, carrying both noise in and out. Shielding and grounding them properly prevents these long conductors from becoming weak points.
Recommended techniques:
• Foil + Braid Combinations: Foil shields block high-frequency noise, while braids add mechanicaldurability and low-frequency shielding.
• 360° Termination: Connect shields fully around the circumference at the connector, not just a pigtail
lead.
• Drain Wires: Provide an easy, low-resistance ground connection for foil shields.
• Shield Grounding Strategy: For short cables, ground at one end; for long, high-frequency cables,
ground at both ends to minimize radiation.
• Twisted Pairs: Even without shielding, twisted pairs reduce differential-mode EMI and improve noise
rejection.
Applications of These Practices
Conclusion
Effective EMI control is a system-level responsibility, combining good grounding, robust enclosure shielding, and proper cable design. By implementing these best practices early in the design phase, engineers can significantly reduce compliance risks, improve reliability, and extend product lifespans.
At PICA Manufacturing Solutions, we help customers design and manufacture electronics with built-in EMI resilience—so your products perform reliably in even the harshest environments.
Need guidance on EMI shielding strategies? Contact us at picamfg.com to collaborate with our engineering team.