Types Of Wire and Cable Shielding Explained: Foil vs. Braid vs. Tape
Shielding in cables exists to protect cables from electromagnetic interference. Common types of shielding are foil, braid, and others. Shielding is used in communication cables, and power cables of medium and high voltage. Read this blog to learn the primary differences between various types of shielding.
Most Popular Types Of Cable Shielding
Foil shield is a type of shielding that offers moderate protection from electromagnetic interference. This is a very thin layer of aluminum attached to polyester for extra strength. While the protection from the EMI is not the strongest, the aluminum foil shielding has benefits for many applications.
It is more lightweight and allows for the smaller diameter of a cable. This type of shielding is ideal for protection from low-frequency electromagnetic interference. With this shielding, the coverage is close to 95-100 percent.
Braid shield consists of metal conductors connected in a crosscut pattern, hence the name braid. This metal braided shielding is made of bare or tinned copper. Other metals, such as steel, are also a possibility.
It is a flexible and robust shielding that gives confident levels of protection against high-frequency electromagnetic interference. However, the coverage is only between 40 percent and 95 percent due to shielding construction. A 40 to 96 percent coverage is the most common. Braid shielding is generally more expensive than foil. It is also more difficult to terminate.
Other Types of Cable Shielding
Foil/braid shield is a combination of foil and braid shielding. The two types of shielding are combined for improved coverage and effectiveness. Like braid shielding, it is strong and flexible but slightly lighter.
Tape shielding, or shielding tape, is the lightweight shielding wrapped around the cable conductors. This shielding is made of various materials, usually a combination of copper, aluminum, and bronze, with polyester or mylar. Polyester and mylar are similar materials, as the latter is simply a brand of polyester. The shielding also has a drain wire.
Tape shielding has properties similar to foil shielding and provides complete coverage of approximately 100 percent. While tape shielding is mostly a part of the standard cable construction created by the manufacturer, it can also be DIY. One significant difference between foil shielding and tape is that the former is always aluminum.
Spiral shielding is the analog of the braid. This type of shielding is made of copper. The shielding is called spiral because the strands are wrapped around the conductor in a spiral shape. The coverage is around 95 percent.
The factor that distinguishes spiral shielding from the braid is that the spiral is more flexible. Moreover, it is way easier to terminate.
Copper vs. Aluminum for Shielding
While some other metals are also popular, copper and aluminum are common materials for shielding. Aluminum is used in foil shielding, while copper is often applied in braid shielding.
While copper and aluminum are very often judged based on their conductivity, conductivity does not matter when protecting from electromagnetic interference. One factor that should be considered is that copper is easier to solder than aluminum. However, when it comes to choosing to shield, the type of shielding is more important than the material it is made from. So, feel free to pick your shielding based on its type.
