Electromagnetic interference, commonly known as EMI is a kind of electromagnetic radiation that can damage, lessen or interrupt the functions of electronic devices and equipment.
EMI can travel along conductors, electrical circuits and wires. Similarly, radio frequency interference (RFI), which is radiated electromagnetic “noise,” travels through the air as radio waves, where it causes the same problems as EMI.
Generally appearing in the form of an enclosure, transmitted signal or coating, EMI shielding engages in a process that was developed to protect vulnerable electronics from the influence of EMI and RFI. Read More…
EMI shielding stops EMI and RFI from entering or exiting a certain region by creating a barrier from magnetic or conductive materials. As though it were under a dome, a shielded device is isolated from everything outside. External fields cannot infiltrate the device, and internal fields cannot escape to affect other sensitive equipment. Any industry that uses modern communication devices depends on EMI shielding products.
EMI enclosures, also called faraday cages, work by surrounding, or enclosing, the equipment it is shielding. EMI enclosures can be solid, but this not a necessarily a requirement; if an application allows for it, they may also be made of perforated metal. The only stipulation is that the metal holes must be smaller and closer together than the electromagnetic waves they are blocking. To visualize this, picture a microwave oven, which utilizes them. Each wall within the microwave is made of a perforated metal sheet. These sheets stop microwaves from escaping while allowing just enough light to pass through for us to see in.
Typically, an EMI coating is made by joining a carrier material to a conducting metal, such as nickel or copper, which together form a metallic ink; this metallic ink, also called a metal ink, is the coating. To provide flexible shielding, EMI coating is sprayed onto the inside of non-conductive enclosures, on wires and on interior of other electronic device housings. In addition, for stronger protection, EMI gaskets play a supporting role opposite EMI and RFI shielding by sealing gaps and or seams between enclosures.
As technology advances and electronic equipment signals grow stronger, more robust shielding, like that provided by gaskets, is needed more and more. An alternative to all these shielding devices is the EMI filter.
An EMI filter is a passive electronic device that suppresses EMI created and emitted by surrounding electronic devices and equipment. EMI filters are specifically used to block the incoming and outgoing non-RFI interference that is conducted through power lines and signals. They can also shunt high EMI frequencies to allow normal and low frequencies to come and go. To do so, they are usually integrated into or attached to the switch or power source that they are shielding.
The materials used to create EMI and RFI shielding are fairly varied. The EMI shielding process requires a conducting surface, so it uses almost only metal. While copper, steel and steel alloys, aluminum and nickel are all commonly utilized shielding materials, the industry standard is an alloy called MuMetal®, which has elements of iron, copper, nickel and molybdenum.
Similarly, EMI enclosures are generally constructed using solid or perforated stainless steel, nickel, copper alloy or aluminum. Usually, gaskets are die-cut pieces made of electrically conductive rubber materials, attached to an EMI shield.
Whether or not we are cognizant to it, EMI and RFI shielded products are a part of our everyday life. For instance, cable wires use simple metallic shells as shields. CPUs and circuit boards all use EMI coatings or EMI enclosures to limit interaction between the electromagnetic fields that they individually generate.
CPUs include but are not limited to desktop computers, laptop computers, tablets and more. In addition, all mobile phones give off RFI that must be blocked. So, in a way, our whole world runs on EMI shielding.