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Understanding EMI Shielding

Electromagnetic interference (EMI) shielding uses electrically conductive or magnetic materials to block electromagnetic interference in a given area. Electromagnetic interference can occur naturally in the form of solar flares, lightning, and aurora borealis. It is also caused by human activity such as cell phone signals, engine ignition switches, computers, and electrical equipment.

Due to the widespread use of sensitive electronic equipment for everything from transportation to banking and utility infrastructure, it is more important than ever to ensure the safety of electronic systems through the use of EMI shielding products and dedicated techniques. With the proper EMI protection, electronic systems will remain reliable and dependable in the face of both natural and man-made electronic interference.


Understanding EMI Shielding

Although electromagnetic waves are extremely common in this day and age, they still present a wide array of issues for sensitive equipment. EMI can cause anything from temporary interruption of system operations to critical failures. Depending on the application and equipment, such disturbances can be expensive, time consuming, and even dangerous to the health and safety of workers. For this reason, EMI shielding is a critical component for any system that is susceptible to electromagnetic interference.

Electromagnetic interference is essentially radiation energy that exhibits either a magnetic or electric field. This type of energy spans a broad range of visible and invisible radiation spectrum, and includes:

  • Gamma rays
  • Longwave radiation
  • Microwaves
  • X-rays
  • Radio and television waves
  • Ultraviolet radiation
  • Infrared light and heat

Due to the ubiquity of electronic equipment, it is no surprise that numerous critical applications and industries are at risk of damage due to electromagnetic interference. The medical, military, industrial, aerospace, and transportation sectors all require reliable electrical systems that cannot be interrupted without dangerous consequences. For this reason, it is more important than ever to have reliable EMI shielding.


EMI shielding comes in a variety of materials and designs, and can be engineered to meet the needs of specific equipment and applications. Components that may be modified for use in EMI shielding arrays include gaskets, wires, tapes, metal screens, and laminates, among many others. It is important to select the right material for the application to ensure optimal shielding of radiation at the correct wavelengths.

Some of the most common materials used in EMI shielding include:


Carbon steel is often used in EMI shielding equipment, due to its exceptional strength and durability. It serves as an excellent shielding material for low-frequency magnetic waves, but can be heavier than other shielding materials and is susceptible to corrosion and oxidation. As an alternative, galvanized steel is an inexpensive and widely used shielding material that has been heat treated and exhibits a protective coating to prevent rust and corrosion.


Like galvanized steel, aluminum is less expensive than other shielding materials. Aluminum is lightweight, strong, and highly conductive, which makes it particularly useful for blocking a wide range of electronic waves. Of note, however, it is less effective than steel for protection against low-frequency electromagnetic radiation.


Copper is by far the most popular EMI shielding material for radio and magnetic frequencies. It is highly conductive and easily formable, and easily absorbs magnetic, radio, and electrical waves. Although it is highly effective as a shielding material, pure copper may erode when exposed to certain elements in air and water.


To mitigate pure copper’s susceptibility to oxidation, Copper Alloy 770, a blend of copper, nickel, and zinc, is often used for EMI shielding products. Copper Alloy 770 exhibits similar radio and magnetic wave absorption without the potential for corrosion.


Tin-plated steel is a popular inexpensive EMI shielding material that is ideal for radiation in low kHz and GHz frequencies. Like plain carbon steel, tin-plated steel protects equipment from low-frequency magnetic waves with the added benefit of corrosion protection. In addition to enhancing the material’s corrosion resistance, tin plating can easily be soldered to system components.


At Robert McKeown, we know that electromagnetic interference can have lasting negative effects on electronic equipment. We are dedicated to providing the highest quality EMI shielding solutions for reliable, long-lasting protection of your electronic systems. To learn more about our superior EMI shielding products and services, contact us today or request a quote.