Understanding EMI/RFI Shielding Materials and Their Applications in Electronics

04/01/2025

Electromagnetic interference (EMI) and Radio Frequency Interference (RFI) are some of the biggest challenges facing the modern electronics industry. As devices become increasingly compact and interconnected, they become more vulnerable to external electromagnetic fields that can disrupt their operation. Without proper shielding, EMI can penetrate a device, degrade signal integrity, and even lead to system failure. Shielding may also protect nearby components from radiation emitted from a device.

To mitigate these risks, EMI/RFI shielding has become a critical consideration for engineers during the electronic design phase. With effective shielding in place, you can protect sensitive components from both EMI and RFI, delivering stable and reliable operation. Beyond just performance, shielding also ensures compliance with strict industry standards such as FCC, CE, and MIL-STD regulations.

Fotofab has been a trusted leader in precision chemical etching, providing high-quality, custom metal components since 1967. Delivering expertise, reliability, and quality, our expert team specializes in chemically etched EMI and RFI shielding enclosures for leading industries like medical, military, and aerospace. Masters of material selection, we consistently deliver tailored EMI shielding solutions for the most demanding environments.

In this article, we look at how shielding protects your products, the most effective EMI materials, common industry applications, and the key factors influencing material selection.

Protecting Your Product: The Importance of Shielding

Electromagnetic interference (EMI) is the unwanted disruption of electronic signals caused by external electromagnetic fields, which can originate from natural sources such as lightning or man-made sources such as mobile phones, industrial equipment, and wireless communication networks. Radio frequency interference (RFI), a subset of EMI, specifically refers to interference within the radio frequency spectrum (3 kHz to 300 GHz), which can disrupt wireless communications and precision electronic systems.

EMI and RFI can interfere with sensitive electrical equipment and result in operational errors, reduced efficiency, and even total system failure.

Effective EMI/RFI shielding, achieved through conductive metal enclosures or coatings, is essential to maintaining the reliable performance of equipment and devices. By controlling both broadband EMI and high-frequency RFI, manufacturers can ensure the accuracy of automated systems, protect sensitive electronics, and comply with industry standards for electromagnetic compatibility (EMC).

Understanding how electromagnetic energy (EME) behaves within a specific application environment is essential for effective electromagnetic interference shielding. EMI shields function by either reflecting or absorbing electromagnetic waves and preventing disruptions to circuit performance. Engineers must account for the interaction between radio frequency (RF) fields and electronic components, as RFI can introduce high-frequency disturbances in communication technologies and signal-processing systems. The presence of an external magnetic field can further influence EMI shielding effectiveness, potentially altering the behavior of RF waves. While RF waves are crucial for communication technologies, they can also introduce interference in sensitive systems.

How Does EMI/RFI Shielding Work?

EMI/RFI shielding materials, such as conductive metals or conductive coatings, create a barrier between the electronic device and external electromagnetic fields. These materials act as a shield, reflecting or diverting electromagnetic waves away from sensitive components and preventing EMI penetration into the device. Shielding effectiveness depends on factors like material conductivity, thickness, and the frequency range of the interfering signals.

Common EMI/RFI Shielding Materials

Without the right materials, any attempt to shield against EMI/RFI will be ineffective, putting your sensitive devices at risk of failure. Electromagnetic waves can easily penetrate non-magnetic materials such as wood, glass, ceramics, and non-conductive plastics, leaving unprotected devices vulnerable to interference.

The materials that are most effective for electromagnetic shielding generally fall into three categories:

1. Metals

Metals are the most widely used materials for EMI/RFI shielding due to their excellent electrical conductivity and ability to reflect electromagnetic waves. Common metals include:

Copper: Its high conductivity, corrosion resistance, and easy fabrication make copper a top choice for magnetic shielding.
Aluminum: Lightweight and cost-effective, aluminum provides effective EMI shielding, though it requires protective coatings to prevent oxidation.
Nickel: Often used in coatings and alloys for enhanced corrosion resistance and shielding performance.
Stainless Steel: Strong, durable, and corrosion-resistant, making it suitable for demanding environments.
Brass: Provides moderate conductivity and is easy to form and solder, making it suitable for general-purpose EMI shielding.
Nickel Silver: Excellent shielding, corrosion-resistant, and non-magnetic, ideal for sensitive electronic enclosures.

Here at FotoFab, we’ve learned that shielding against frequencies of 15 MHz or lower is a bulk material effect, and can best be served by employing a ferromagnetic metal such as Steel. For greater attenuation at these lower frequencies, alloys with high permeability and low core losses such as Permalloy 80® or MuMetal® are good candidates.

If the frequencies you are shielding against are greater than 15 MHz, RFI, and EMI shielding become less of a bulk material effect and more of a skin (conductivity) effect. At frequencies (and harmonics) of 900 MHz and above, almost any metal, including Brass, Nickel Silver, Copper, and Steel, shields similarly assuming a thickness of .002″ (.05 mm) or greater.

2. Metal Alloys

Specialized alloys offer unique shielding properties. One such example is MuMetal®, a nickel-iron alloy known for its high magnetic permeability, making it ideal for shielding low-frequency EMI. MuMetal®‘s high permeability and low core losses make it perfect for greater attenuation at lower frequencies.Nickel Silver, a copper-nickel-zinc alloy, is widely used for high-frequency EMI shielding due to its excellent conductivity, corrosion resistance, and non-magnetic properties. Unlike MuMetal®, it does not require annealing for effectiveness and performs well in harsh or humid environments where oxidation resistance is essential.

3. Coatings

Shielding materials can be combined with surface coatings such as tin, gold and nickel, providing EMI/RFI protection while accommodating complex geometries. These materials are commonly used in consumer electronics and automotive applications.

Industry-Specific Applications

EMI shielding solutions are essential across various leading industries because they protect sensitive electronic systems from electromagnetic interference, ensuring reliable performance and operational safety.

Aerospace

In aerospace applications, shielding prevents signal disruptions in navigation, communication, and control systems.

Effective shielding is essential for protecting avionics and communication systems from external electromagnetic interference, utilizing lightweight metals such as aluminum and specialized alloys to ensure effective shielding while maintaining weight efficiency.

Medical Devices

In the medical field, the health and safety of patients rely on the effectiveness of shielding. By protecting sensitive diagnostic equipment and implantable devices from EMI, shielding ensures accurate readings and keeps patients safe. Metals such as stainless steel, including non-magnetic 316/316L, non-magnetically plated copper, and titanium are generally used to provide a strong shield that also complies with strict medical standards.

Telecommunications

Shielding plays a crucial role in telecommunications by ensuring signal integrity in networking equipment, smartphones, and broadcasting devices. This involves applying copper and nickel coatings to housings and components to prevent signal degradation and ensure reliable performance.

Electronics

EMI shields are an important part of modern electronics, preventing interference in devices such as laptops, tablets, and wearable technology. Thin metallic electrical conductive coatings such as gold and tin are applied to offer effective shielding without adding bulk to the devices.

Factors Influencing Material Selection

Material selection is critical for EMI shielding because it directly impacts the effectiveness, durability, and practicality of the shielding solution. Different materials offer varying levels of conductivity, permeability, and attenuation, which determine their ability to reflect or absorb electromagnetic interference.

The right material ensures optimal protection against EMI while meeting the specific requirements of different industries, from aerospace and telecommunications to healthcare.

Choosing the right EMI/RFI shielding material depends on multiple factors:

Frequency Range: Different materials perform optimally at specific frequencies. Understanding the EMI frequency spectrum is essential for effective shielding.
Environmental Considerations: Temperature fluctuations, humidity, and exposure to corrosive elements influence material performance.
Mechanical Requirements: Design constraints such as weight, flexibility, structural integrity, and formed geometries impact material selection.

Regulatory Compliance: Industry standards and certifications, such as RoHS, dictate material choices to ensure safety and effectiveness.

Fotofab’s EMI/RFI Shielding Solutions – Protect Your Components with the Right EMI/RFI Technology

For industries requiring precise and reliable EMI/RFI shielding solutions, Fotofab delivers standard, custom, 5-sided, and multichannel shielding enclosures designed with tight tolerances to ensure optimal performance. Whether you need low-profile shields for compact applications or standard RF shields for broader protection, our expertise in precision photochemical machining guarantees intricate, high-quality shielding components. Fotofab’s standard shields can be provided with etched bend-channels, allowing easy manual forming without tools

From prototyping to large-scale production, Fotofab supports your shielding needs every step of the way. If your enclosure design is intended for high-volume manufacturing, our progressive die stamping service provides the most cost-efficient solution. Our technical specialists will guide you through design considerations during the prototyping phase, ensuring a seamless transition to mass production.With a focus on customization, we tailor EMI/RFI shielding solutions to meet your exact specifications, offering flexible material choices to optimize performance. Our material expertise ensures you select the best option for durability, effectiveness, and cost efficiency.

Protect the Performance of Your Equipment and Devices

Effective EMI shielding is crucial for ensuring the performance and reliability of electronic devices across a range of modern industries. From aerospace to medical devices and semiconductors, effective shielding is required to protect the device and the people using it.

Selecting the appropriate EMI/RFI shielding material is not just about blocking interference—it’s about optimizing product functionality, regulatory compliance, durability, and cost.

If you’re looking to protect your sensitive electronics from EMI and RFI, you can’t go past Fotofab’s industry-leading shielding materials, shaping, and finishing options. Experts in precision metal manufacturing and photochemical etching, we leverage our advanced manufacturing capabilities and material expertise to develop shielding solutions that ensure the highest performance and safety standards are met.

For high-precision, reliable EMI & RFI shielding solutions, trust Fotofab.