Quietshield
™
Gaskets & Shielding
Signal & Power Integrity Group
With years of experience in the design
and manufacture of filtering and
shielding products, Spectrum Control
has a unique perspective on EMI and
its control. Spectrum Control offers
all the products necessary to protect
electrical equipment from failures
due to EMI.
As part of our broad range of
products, Spectrum Control offers a
line of shielding products intended to
enable the user to seal their electronic
enclosure. A variety of products are
available including fabric-over-foam,
conductive elastomer and wire
mesh gaskets.
In combination with our filtering
and TVSS products, Spectrum Control
can solve EMI problems while providing
you with increased design flexibility,
reduced time-to-market and peak
system performance.
Index
Page
Gasket & Shielding Selection Guide.......3
Shielding Theory and Introduction ........4
Quietshield Gaskets ................................5
Quietshield
Fabric-over-Foam Gaskets ...................6-7
Shielding Tapes & Fabric........................8
Wire Mesh Gaskets .................................9
Conductive Elastomers .........................10
Part Number System ............................11
CERTIFIED
2
www.specemc.com/quietshield
Gaskets & Shielding
Selection Guide
Fabric
Over
Foam
Waved Metal
and Fabric
Over Foam
Metal
Mesh
Conductive
Silicone
Fabric & Tape
I
Low cost
I
Low closure force
I
High shielding
effectiveness
I
Multiple fabric plating
and core material
I
PSA attachment
I
Commercial enclosures
I
Electronic cabinets
I
Electrical test units
I
Tempest computers
and peripherals
I
Standard D-Sub shapes
I
Improves grounding
I
Improves high frequency
attenuation
I
Low cost
I
High shielding
I
Multiple fabric plating
I
Conductive or
nonconductive PSA
I
Sheet or standard widths
I
Profiles, sheets
or gaskets
I
Aluminum, stainless
I
Elastomer core available
I
Excellent heat and
corrosion resistance
I
High conductivity
I
Electronic enclosures
I
Industrial control
I
Good shielding
I
Excellent water
resistance
I
Control static electric
discharge
I
High frequency absorber
I
Telecommunications
equipment
I
Cellular base stations
I
Secured communications
I
Medical electronics
I
Industrial process
equipment
I
Aerospace applications
I
Commercial enclosures
I
Electrical cabinets
I
Unshielded cables
and wires
I
Military equipment
I
Tempest systems
I
Outdoor communications
Applications
I
FED/MIL Approvals
UL 94VTM-1,
V0 core optional
I
Shielding Effectiveness
Range/Performance
I
Shielding Effectiveness
Range/Performance
1 MHz - 5 GHz
I
Temperature Range
-55º C to +125º C
I
Compression
80%
I
FED/MIL Approvals
UL 94VTM-1,
I
Shielding Effectiveness
Range/Performance
68-88 dB from 30 MHz
to 1 GHz
I
Temperature Range
To 200º C
I
Surface Resistance
<0.08 ohms
I
Compression
<5%
I
Shielding Effectiveness
Range/Performance
1 MHz to 5 GHz
I
Temperature Range
-55º C to 200º C
I
Surface Resistance
<0.08 ohms
I
Compression Set
15%
I
Shielding Effectiveness
Range/Performance
60 dB at 30 MHz to 1 GHz
I
Temperature Range
-55º C to 200º C
I
Surface Resistance
5 -10 ohms-cm
I
Elongation %
240%
Performance Characteristics
68-88 dB from 30 MHz
to 5 GHz
I
Temperature Range
To 200º C
I
Surface Resistance
<0.08 ohms
I
Compression Set
<5%
SPECTRUM CONTROL INC.
• 8031 Avonia Rd. • Fairview, PA 16415 • Phone: 814-474-2207 • Fax: 814-474-2208 • Web site: www.specemc.com
SPECTRUM CONTROL GmbH
• Hansastrasse 6 • 91126 Schwabach, Germany • Phone: (49)-9122-795-0 • Fax: (49)-9122-795-58
3
Shielding Theory and Introduction
Shielding Theory
Electromagnetic shielding is used to prevent electromagnetic
signals such as radio signals from leaving or entering a box
or enclosure. Signals inadvertently emitted by an electronic
device can cause distortion or interruption in normal radio
communications in a localized area. This is the basis of
most laws and regulations concerning electromagnetic
interference. In addition, normal radio signals can cause
unprotected electronic devices to malfunction. Depending
on the device’s function, a malfunction in the device could
be a minor inconvenience such as static on a radio, or life
threatening such as the malfunction of a life support system
at a hospital.
The shield will continue to function as long as there are
no holes in the electromagnetic shield which would allow
the currents to flow from one side of the shield to the other.
Holes are a necessity in an electronic enclosure. Connectors,
wires, and cables are needed to transmit information to and
from electronic devices. Doors and covers are needed to
get access to components to maintenance, service, and
keypads may also be required. The problem is that all of
these items cause openings in the shield which reduce
the performance of the shield.
Special devices such as shielding gaskets, shielding
ventilation panels, shielded filtered connectors, and shielded
switches minimize the effect of a hole in the shield.
The length of the hole and wavelength of the signal
that needs to be shielded are the major factors determining
the shielding effectiveness of an electronic enclosure. The
distance between spotwelds, or screws which hold a metal
housing together count as long narrow holes. Higher frequencies
(lower wavelengths) flow more easily through smaller holes,
and so the highest frequency needed to be shielded is the
frequency of concern when designing shielding.
Aperture versus frequency charts can give a rough
estimate of the shielding effectiveness of a metallic
electronic housing.
Introduction
The electromagnetic shield in most cases is the electronic
housing itself. The housing/shield forms a metal cage around
the electronic circuits in a device. Most of the electromagnetic
signal is absorbed with a small portion (3 to 10 dB) of the
signal reflected off the metal housing. Most of the absorbed
signal creates alternating currents at radio frequencies which
travels on the surface of metal. This allows the
electromagnetic shield to keep signals from outside the
enclosure on the outside of the shield and signals from
inside signals on the inside of the shield.
SHIELDING EFFECTIVENESS
100.
TYPICAL SHIELDING EFFECTIVENESS
110
100
Aperture Length (Wavelength - Inches)
40 dB
60 dB
10.
80 dB
1.
20 dB
Wavelength
to
Frequency
Shielding Effectiveness (dB)
100GHz
90
80
70
60
50
40
30
20
10
0
0
100
200
300
400
500
600
700
800
900
1000
.1
.01
.001
100 KHz
1 MHz
10MHz
100MHz
1GHz
10GHz
Frequency (MHz)
Frequency (MHz)
Test Methods: ASTM D-4935-89
Test Fixture: Flanged coaxial transmission line
4
SPECTRUM CONTROL INC.
• 8031 Avonia Rd. • Fairview, PA 16415 • Phone: 814-474-2207 • Fax: 814-474-2208 • Web site: www.specemc.com
SPECTRUM CONTROL GmbH
• Hansastrasse 6 • 91126 Schwabach, Germany • Phone: (49)-9122-795-0 • Fax: (49)-9122-795-58
Quietshield
™
Fabric-over-Foam Gaskets
Features
I
I
I
I
I
Maintain shielding effectiveness across seams or gaps
Shielding Effectiveness (SE) of 70 - 100 dB between
1 MHz to 18 GHz
Flexible and conformable
No creasing or tearing
Lightweight material
I/O Gaskets
Spectrum Control offers a complete line of standard and
custom I/O connector Electromagnetic Shielding Gaskets.
I/O gaskets are flat gaskets used to provide a ground
contact between a metal connector and the electronic
enclosure or mating connector. They insure that the shield
remains continuous from the input/output cable to the
electronic enclosure.
I/O Gaskets are available in the same materials as the
fabric-over-foam profile gaskets, or as all-metal waved gaskets.
Spectrum Control’s line of metal waved gaskets is
designed to minimize the gaps between a D-Sub connector
and the panel it is mounted to. These gaskets ensure the
maximum “gap length” will not exceed the wave pitch, 0.200"
(5.08 MM), even on surfaces with poor flatness. This ensures
maximum filter performance to 1GHz and beyond.
Profile Gaskets
Quietshield EMI/RFI Gaskets maintain shielding effectiveness
(SE) across a seam or gap in the electronic equipment’s
shielding material.
Quietshield gaskets provide unique solutions to your
most stringent shielding, grounding, ESD and packaging
requirements. It’s the cost-effective avenue for creativity in
design. These gaskets consist of polyurethane foam
combined with highly conductive fabrics. Specially designed
polyurethane foam is soft, resilient and provides the perfect
fit. Our gaskets are made with seven different types of
fabric plating and two types of thermal adhesive, standard
or flame retardant. Our flame retardant adhesive complies
with UL94VTM-1 and VTM-0. If necessary, the polyurethane
foam core can also be plated with Cu and Ni to provide
additional conductivity.
Fabric-over-Foam Gaskets, unlike elastomer or finger
strip gaskets, provide softness for easy application with
a variety of materials and designs at low cost. The best
quality with high conductivity, low electrical resistance and
minimum oxidation can be achieved by using gold gaskets
with additional gold plating to provide superior shielding.
Profile gaskets are currently available in a variety of shapes
and lengths. Spectrum Control’s gaskets provide a variety of
applications with lightweight and flexible solutions. Various
thicknesses and shapes are available. These range from
commonly used ones such as rectangular and “D” shape,
to uncommon ones such as FL-shape (folding leaf) and
DD-shape (Double DD-shape). We are able to produce
gaskets with different shapes and sizes, based upon the
customer’s requests.
The mounting style available for most profile gaskets is
pressure sensitive adhesive.These adhesives allow simple
place and press mounting on smooth and clean metal
surfaces.The parts can be cut to the desired length with
common scissors or ordered to the exact length required.
The adhesive provides high strength with aggressive initial
tack, which increases in strength over time or after exposure
to elevated temperatures.
Test
Shielding Effectiveness, dB
Compression Set %
Compression Load Deflection,
PSI
Compression at Max Load
Water Absorption
(Foam Only) %
Abrasion Resistance,
3,000 Cycles
Ultra Violet Exposure
Fungus Exposure
Operating Temperature C
Flammability Rating
Conductivity, OHMS/SQ
Unexposed
Weathered (100 HRS)
Fungus
Salt
DC Conductivity
Tensile Strength
ASTM
Test
D3574
D3574
Performance
70-100
7.9
15
60%
5.8
Excellent
No Visible Change
Small Growth
-40˚ to +90˚
VTM1, VTM0
0.2
0.3
0.2
0.2
.2 Ohms/SQ
80 lb/in
D1667
D3885
D750
G21
D746
UL94
SPECTRUM CONTROL INC.
• 8031 Avonia Rd. • Fairview, PA 16415 • Phone: 814-474-2207 • Fax: 814-474-2208 • Web site: www.specemc.com
SPECTRUM CONTROL GmbH
• Hansastrasse 6 • 91126 Schwabach, Germany • Phone: (49)-9122-795-0 • Fax: (49)-9122-795-58
5
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