EMI Gasket Sheet Comparison: How to Choose the Right Material

Introduction

As electronic devices become increasingly compact—and with rapid growth in 5G/6G communications and electric vehicles—electromagnetic compatibility (EMC) has become a decisive factor in product success.

Among all EMC components, the EMI Gasket Sheet is one of the most flexible and widely used solutions.
Its material selection directly determines:

• Shielding effectiveness

• Long-term reliability

• Overall system cost

However, engineers often face confusion when comparing conductive foam, conductive elastomers, and metal spring fingers.
Which material truly fits a specific project?

This guide provides a deep technical comparison of five mainstream EMI gasket sheet materials, clarifies their performance boundaries, and delivers a clear selection methodology for optimal EMC design.

1. Core Fundamentals — What Determines EMI Gasket Performance?

Before comparing materials, three key performance dimensions must be understood.

1. Shielding mechanism

• Reflection-dominant → highly conductive metals

• Absorption-dominant → magnetic fillers

• Hybrid reflection + absorption → composite systems

This determines effectiveness across low- to high-frequency bands.

2. Environmental adaptability

Temperature resistance, corrosion resistance, and compression set stability define service life in:

• Automotive

• Outdoor infrastructure

• Aerospace

3. Interface conformity

Hardness, compression force curve, and resilience determine whether the gasket can maintain:

• Stable low-impedance grounding

• Tolerance compensation

• No structural deformation

2. Deep Comparison of Five Mainstream EMI Gasket Sheet Materials

2.1 Conductive Foam Gasket

Structure:
PU/CR/silicone foam core wrapped with metalized conductive fabric or PI film.

Shielding mechanism:
Reflection-dominant via surface conductivity.

Advantages

• High compression ratio (up to 70%)

• Excellent resilience and lightweight

• Flexible die-cut customization

• Strong cost-performance balance

Limitations

• Possible compression set over long cycles

• Foam aging above 125 °C or below -40 °C

Typical applications

• Smartphones and tablets

• Networking enclosures

• Industrial control cabinets

Konlida innovation such as AIR LOOP hollow structure reduces compression force by 70% while maintaining 60–90 dB shielding, solving large-display assembly stress issues.

Related reading:
See signal integrity challenges in mobile devices:
https://www.konlidainc.com/article/signal.html

2.2 Conductive Elastomer Gasket

Structure:
Silicone or fluorosilicone filled with silver, silver-plated copper, nickel, or graphite particles.

Shielding mechanism:
Combined reflection + absorption through conductive particle networks.

Advantages

• Excellent IP sealing (dust, water, moisture)

• Wide temperature range: -55 °C to 200 °C+

• Strong corrosion resistance

• Low compression set and long lifetime

Limitations

• Higher hardness and compression force

• High material cost (especially silver-filled)

• Mold-dependent customization

Typical applications

• Aerospace and military electronics

• Outdoor base stations

• EV battery packs and motor controllers

Example automotive EMC context:
https://www.konlidainc.com/article/bms.html

2.3 Metal Spring Finger Gasket

Structure:
Precision-stamped beryllium copper or stainless steel finger or wave springs.

Shielding mechanism:
Pure metal reflection shielding.

Advantages

• Extremely high shielding effectiveness (>100 dB)

• Excellent conductivity and durability

• Withstands frequent mating cycles

• Minimal aging

Limitations

• High cost

• Requires precise flat contact surfaces

• Corrosion protection relies on plating

• Structural installation complexity

Typical applications

• Military communication chassis

• High-end test instruments

• Shielded room doors

• Service access panels

2.4 Isotropic Conductive Foam

Structure:
Open-cell foam with full-volume metallization or conductive particle filling.

Shielding mechanism:
3D isotropic conductivity enabling current flow in all directions.

Advantages

• Arbitrary cutting and flexible processing

• Cushioning and vibration damping

• Low cost

Limitations

• Moderate shielding (50–80 dB)

• Lower mechanical strength

• Surface wear sensitivity

• Limited high-frequency performance

Typical applications

• Local PCB shielding

• FPC grounding

• Camera modules

• Cost-sensitive electronics

2.5 Flexible Absorber Sheet

Structure:
Ferrite or magnetic alloy powders dispersed in silicone or polymer matrix.

Shielding mechanism:
Absorption-dominant, converting EM energy into heat.

Advantages

• Suppresses cavity resonance and Q-factor

• Improves signal integrity

• Thin, soft, and lightweight

Limitations

• Not highly conductive

• Usually combined with reflective gaskets

Typical applications

• Smartphones and laptops

• Antenna isolation

• High-speed PCB EMI suppression

• SAR reduction

High-frequency EMC optimization reference:
https://www.konlidainc.com/article/obc.html

3. Selection Matrix for EMI Gasket Sheets

Recommended Selection Workflow

1. Define EMC targets
   Shielding level, frequency band, environment, lifetime, and tolerance.

2. Shortlist 2–3 materials
   Based on performance matrix.

3. Evaluate manufacturing cost
   Tooling, processing, and installation.

4. Prototype testing

   • Shielding effectiveness (SE)

   • Compression-resistance curve

   • Environmental reliability

5. Iterative optimization with supplier
   Adjust material parameters and structure.

Conclusion — There Is No “Best,” Only the Most Suitable

Selecting an EMI Gasket Sheet is a precise balance among:

• Shielding performance

• Environmental durability

• Mechanical compatibility

• Cost control

Typical choices:

• Consumer electronics → conductive foam

• EVs & outdoor systems → conductive elastomers

• Military & precision instruments → metal spring fingers

As a leading EMI shielding and thermal management solution provider, Konlida delivers:

• Full material portfolio

• Co-design engineering support

• End-to-end capability from material R&D to precision die-cutting

Ensuring a seamless path from concept to mass production.