No matter, what is the
cause of EMI – man-made or natural, they transmit signals, and that, in turn,
interfere with wireless communications. The outcome of such disturbances may be
severe, ranging from data losses to system failure. Sometimes, these unwanted
energy waves may even lead to loss of lives. For manufacturers of electronic
application, it is, therefore, important to find out the source from where
electromagnetic energy (EME) may penetrate the application environment, leading
to interference. To enable this protection, they often use shielding gaskets
along with enclosures. Besides shielding electronics from harmful radiations,
these components are also intended to cushion the electronic equipment from
mechanical shock. Gaskets need to be made of any soft material. Otherwise, they
may end up damaging the equipment. Fabric over foam shielding gaskets are best
suited for these applications. The high attenuation capacity coupled with low
compression force enables these highly conductive materials to offer a high
level of shielding or grounding for computers, military devices and seams and
apertures used in the telecommunication industry.
Functioning of EMI
Shielding Gaskets
As far as electronic
devices are concerned, conduction of electricity between the two surfaces is
important to avoid overheating and damages. Gaskets are intended to create a
conductive path between these two planes, and facilitate the dissipation of
current. This system improves the reliability of your system. Most importantly,
these gaskets protect your device from EMI disturbances, preventing any damage to
its electrical circuits. Here is how
these soft gasket materials work to protect electronics from harmful
radiations:
In the early days of
EMI shielding, gaskets were crafted out of sheets of strong and rigid metals
like steel, aluminum and copper. These metallic sheets were then given desired
shapes to match the shape of the enclosure. However, thin sheets tend to get
deformed easily in the situations where high pressure is applied for sealing.
Deformed sheets, then, become incapable of containing radiation, allowing for
the energy waves to interfere with electronic circuits. Fabric over foam shielding gaskets are free
of these limitations, and, therefore, offer high shielding effectiveness.
Depending on unique
application needs, budget and difficulty level relating to fabrication, today’s
top manufacturers use a variety of materials to create fabric over foam shielding
gaskets. In some cases, metal-filled polyurethane foam is used where the material
is placed between the layers of fabrics. These types of constructions are ideal
for applications that require low compression forces. However, for gaskets that
are meant for use in sensitive applications like touchscreens, are generally
composed of particle-filled silicones. Apart from providing attenuation and
electrical conductivity, these materials also provide excellent environmental
sealing in extreme conditions. Moreover, these gaskets also provide soft
cushioning, which enables the display screen to carry on with an uninterrupted
touch function.
Four Major EMI Shielding
Gasket Fabrication Methods
The causes of EMI may
be countless, but so are the ways you can shield your applications. One of the
ways is using a fabric-coated gasket. Gaskets can provide the much-needed
environmental sealing but it has to be fabricated to match the shape and size
of your device. Different manufacturing methods are used to customize gasket
design.
Die-Cutting
This method is ideal
where mass production is involved. Die-cutting enables manufacturers to
fabricate five to 500,000 gaskets at one go. All that is needed is the
specification. This precision system proves effective in producing gaskets
quickly. It’s a repetitive procedure, and therefore, highly cost-effective.
Under this method, gaskets are tied with a fastener through holes or slots with
predetermined radii. If your design cannot support this method, you can also
use pressure sensitive adhesive backing (PSA) to assemble the gasket to your
design. Since die cutting involves minimum assembly time, it is a preferred
choice of manufacturers seeking to expedite production time. One of the
greatest advantages of using this method is, many top manufacturers in the USA
offer these products, and, therefore, you can quickly and conveniently procure
them to meet your application needs.
Extruding
Some applications,
especially the flange and groove units require extruded gaskets. Some of these
pressed out systems come complete with anti-stretch features and can be pushed
to fit into the enclosure. Sometimes, these units are spliced to the enclosure
for achieving more effective sealing. Several leading providers offer these
products in a variety of profiles that may range from hollow and solid square
to O, P, U and more. In these units, the outer layer is made of the fabric over
foam material, which helps in minimizing the use of metals like silver, nickel
graphite or likes. This efficient use of shielding materials help reduce the
production costs, making the product immensely cost-effective.
Form-In-Place
Process
If your device has a
complex design and a narrow PCB area, where densely placed chips require
isolation. These gaskets will be perfect choice for you. Besides offering
excellent shielding, these units create 30 percent lower compression force.
These flexible gaskets can seal the gap more efficiently than any other type of
gaskets. They can be assembled quickly with the help of appropriate tools.
Hence, they are a perfect fit for enclosures with compact designs.
Molding
When you find all three
methods inadequate for your application, you can opt for molding for achieving
a tailor-made design. They are especially suitable for enclosures that do not
support a flat die-cut or extruded design. As such, they make a perfect choice
for applications that call for a three-dimensional design. However,
customization always comes at a price and, therefore, you must ensure that your
budget allows for such modifications.
Different types of
gasket solutions are available from top companies in the industry. However, the EMI shielding technologies are
constantly evolving. Types and methods of assembling gaskets are changing, too,
at a rapid pace. Markets are flooded with products to meet the shielding
requirements of most complex products. To select
appropriate fabric over foam shielding gaskets for your applications, take
help from experts. They will help you choose the right components for creating
reliable and cost-effective shielding.
