The Complete Guide to EMI Shielding for Electronics

Electromagnetic interference (EMI) shielding is the practice of blocking electromagnetic fields from interfering with electronic circuits. At the board level, this typically involves metal enclosures—often called shield cans—that surround sensitive components.

• EMI shielding serves two purposes:
• Containment — Preventing your circuit from emitting interference that affects nearby devices
• Immunity — Protecting your circuit from external electromagnetic interference

Modern electronics require effective EMI management to meet regulatory standards (FCC, CE, CISPR) and ensure reliable operation in the field.

• EMI problems manifest in multiple ways:
• Regulatory failure — Products that exceed emission limits cannot be sold in most markets
• Performance degradation — Unshielded RF circuits suffer reduced sensitivity and range
• System interference — High-speed digital circuits can disrupt analog sections on the same board
• Safety concerns — In automotive and medical applications, EMI can cause safety-critical failures

The cost of addressing EMI late in development far exceeds the cost of proper shielding design upfront. Redesigns, re-certification, and delayed launches can cost 10-100x more than early EMI planning.

Board-level EMI shields come in several configurations:

• *One-Piece Shield Cans
• Single stamped enclosure soldered to the PCB
• Most cost-effective for production
• Requires desoldering for rework

• *Two-Piece Shields (Frame + Lid)
• Solderable frame with removable lid
• Allows rework and component access
• Slightly higher cost, but reduces rework time
• Requires shield can clips for secure retention

• *Multi-Cavity Shields
• Single frame with internal dividers
• Isolates multiple circuit sections
• Reduces component count vs. separate shields

• *Board-Level Shielding (BLS)
• Integrated shielding designed into the PCB stackup
• Typically used with perimeter shields for complete coverage

• *Plating Options
• Tin — Standard, solderable, cost-effective
• Nickel — Corrosion resistance, harder surface
• Gold — Best conductivity, highest cost
• Custom — Application-specific requirements

The choice of material and plating depends on your frequency range, environment, and cost targets.

• *Grounding
• Continuous ground plane under the shield
• Multiple grounding points around the perimeter
• Ground vias near shield attachment points

• *Apertures and Seams
• Keep openings smaller than λ/20 at the highest frequency of concern
• Overlapping seams provide better shielding than butt joints
• Spring contacts improve lid-to-frame conductivity

• *Thermal Management
• Vented shields reduce shielding effectiveness
• Consider thermal interface materials for heat-generating components
• Shield can clips allow airflow in two-piece designs

• *Manufacturing
• Design for pick-and-place compatibility
• Standard footprints reduce tooling costs
• Consider rework requirements early in design

Shielding effectiveness (SE) measures how well a shield attenuates electromagnetic fields. It's expressed in decibels (dB):

Most board-level shields provide 40-80 dB of shielding effectiveness depending on construction and frequency. Contact us for application-specific guidance on achieving your SE targets.

• *For New Designs
• Start with your shielding effectiveness requirements
• Define the frequency range of concern
• Consider rework and testing access needs
• Evaluate thermal constraints
• Request samples for prototype validation

• *For Cost Reduction
• Review current shield specifications—often over-engineered
• Consider one-piece shields if rework access isn't critical
• Evaluate standard dimensions before custom tooling
• Compare material options for equivalent performance

POCONS Advantage As a direct manufacturer, we can help optimize your design for performance and cost. Our sales team works with our Korea R&D team to review applications and recommend solutions based on actual requirements—not catalog assumptions.

EMI shielding components for different industries require specific certifications:

• *Automotive
• IATF 16949 — Quality management system
• AEC-Q200 — Passive component stress test qualification
• OEM-specific requirements (PPAP documentation)

• *Medical
• ISO 13485 — Medical device quality management
• IEC 60601 — EMC requirements for medical electrical equipment

• *General
• ISO 9001 — Quality management system
• RoHS/REACH — Environmental compliance

POCONS holds IATF 16949, ISO 9001, and ISO 14001 certifications. We provide complete documentation packages for your qualification process.

• *Verify Your Supply Chain
• Work with manufacturers, not brokers, for traceability
• Request certificates of conformance and lot documentation
• Audit manufacturing facilities when possible

• *Plan for Lead Times
• Sample lead time: Typically 2-4 weeks depending on specification
• Production lead time: 8-16 weeks depending on complexity
• Build buffer for qualification testing

• *Manage Costs Effectively
• Custom tooling amortizes over volume—factor into piece price
• Standard dimensions reduce or eliminate tooling charges
• Direct manufacturers typically offer 20-30% savings vs. distribution

Ready to Get Started? Request samples to evaluate POCONS components for your application. Our sales team coordinates specification review and design-in support with our Korea R&D team.