EMI Shields
There are many different types of EMI shields, such as gaskets, filters, enclosures and coatings, each of which work best for different applications. EMI gaskets, for instance, are best suited for more industrial applications against EMI which penetrates cracks, gaps and seams to cause equipment malfunction and failure. Alternatively, medical and electronics industries utilize EMI filters to prevent equipment malfunction or lost communication signals. In addition, EMI enclosures work best for applications such as circuit board housings, central processing units, laptops and mobile phone housings, while EMI coatings are beneficial for wire insulation, circuit boards and onto the interior of small enclosures of integrated circuits. In addition, there are a variety of different materials that serve as EMI shields, each with their own advantages.
The various EMI shields function in different ways, and are fabricated from materials with high magnetic permeability, which enables the material to absorb magnetic energy. Some common EMI shield materials include Mu Metal, Permalloy, polyurethane foam and epoxy casting resin. EMI enclosures, however, are typically made from aluminum, stainless steel, copper or nickel alloys. This type of EMI shield serves to surround the equipment which needs to be shielded, absorbing or blocking harmful EMI. EMI gaskets, on the other hand, are commonly constructed from electrically conductive rubber, metal or ceramic materials that are then combined with EMI shielding metals. As an EMI shield, an EMI gasket functions to seals cracks, gaps and seams in equipment against EMI penetration. Conversely, EMI filters are manufactured from perforated or mesh EMI shielding materials and serve to block EMI which is passed along isolated power lines and power signals, thus diminishing electromagnetic "cross-talk" between various electrical devices that run off the same power source. Lastly, EMI coatings are often referred to as "metal inks," containing copper, nickel or chromium alloys. In order for an EMI coating to become an effective EMI shield it must be sprayed on to a housing or material. EMI coatings are the most flexible type of EMI shield because they can be spray-coated to any number of enclosures, areas and insulators.
