Alternatives to Metal Enclosures for EMI Shielding Constraints

Electromagnetic interference (EMI) has the potential to disrupt all manner of electronic devices, equipment, and systems. EMI can disable or cause poor performance in medical devices, military systems, aerospace electronics, navigation systems, and more.

EMI shielding is crucial in protecting circuitry from being disrupted by external electromagnetic signals. It's also essential in preventing signals generated within a device from interfering with other components and nearby devices.

Traditionally, metals of various types have been the material of choice for EMI shielding. There are other options, however, that may prove more useful in certain applications.

Metal is Just One Option for Shielding Against EMI

Manufacturers have typically used metal enclosures – made from aluminum, copper, nickel, and steel – to protect against EMI. Enclosures are fabricated from sheets of metal and formed or assembled into different shapes. Flexible metal screens, metal wires, and metal foams can also be employed.

Metal shielding isn't always the best solution for preventing EMI, however. Metal is often difficult to bend into complex shapes and when deformed can allow electromagnetic leakage. Metal shielding is also thick and heavy and not suited for smaller applications.

Today, many alternative materials are being used to construct EMI shielding. These alternatives include silicone or plastic filled with metal particles and plastic with a metallic coating.

Why Plastic Enclosures Are a Viable EMI Shielding Technique

Thermoplastics do not inherently provide electronic insulation. However, protection against EMI can be added to plastic enclosures, thus retaining the unique advantages presented by thermoplastics.

Advantages of Plastic Enclosures

Thermoplastic enclosures have several significant advantages over traditional metal enclosures, including:

• Weighs less
• Maintains a high strength-to-weight ratio
• Highly resistant to corrosion
• Withstands exposure to extreme temperatures and humidity
• Complex thermoforming enables unique designs with complex contours and multiple fastening options
• Costs less

How EMI Shielding is Added to Thermoplastics

There are multiple ways that thermoplastics can be insulated against electromagnetic signals. These new methods for EMI shielding include:

• Conductive paints, typically containing copper, nickel, or silver particles, used to coat plastic enclosures
• Vacuum metallization, a multiple stage process that deposits a thin layer of aluminum on the plastic
• Electroless plating, a chemical process that deposits a thin layer of copper on the plastic surface, overplated with a layer of nickel
• EMI shielding compounds, where the plastic is filled with conductive fibers made from stainless steel or nickel-coated graphite

EMI shielding compounds have more permanence, are reusable/recyclable, and work better for more complex designs than other options. Plastic with a conductive coating, however, is cheaper to manufacture and more common today. Both approaches enable the use of custom molded plastics for more versatile component design.

Let Kenson Plastics Help You Help You Employ Plastic EMI Shielding in Your Products

Kenson Plastics has been providing precision pressure formed plastics to a variety of major industries since the early 1970s. We offer complex thermoforming, pressure forming, and custom molded plastics suitable for EMI shielding enclosures. We pride ourselves in offering innovative, durable, great-looking, and cost-effective solutions not available elsewhere.

Contact us today to learn more about what we can do for you.