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Electromagnetic Wave Absorbing Sheet “F-CO TM Sheet EMI”

1.

INTRODUCTION

Furukawa Electric and F-CO have jointly developed andbrought into the market F-CO TM Sheet EMI that is lowmolecular-weight siloxane-free and electromagnetic wave
absorbing. F-CO TM Sheet EMI comes in three types—electromagnetic wave absorbing sheet combinedwith thermal conductivity and the one exclusively forelectromagnetic wave absorbing use, and the latterincludes a type that is particularly effective in the low
frequency range. Due to this complete lineup, F-COTM Sheet EMI can be used in many applications forelectronic equipment.

2.

PREVENTION OF ELECTROMAGNETIC
INTERFERENCE (EMI)As various components for electronic equipment improvein performance in recent years, electromagnetic waves
generated by these components are presenting problems
together with heat generation. In particular, digitalequipment that have rapidly diffused into our offices
and homes adversely influence the electromagnetic
environment, so that some countermeasures againstelectromagnetic noise have become indispensable.
There are two ways to prevent such electromagnetic
interference: electromagnetic shielding technology inwhich the electromagnetic noise generated is confinedby shielding taking advantage of reflection from shielding
materials; and electromagnetic absorbing technology inwhich the electromagnetic noise is absorbed and transformed into heat taking advantage of absorbing materials. This electromagnetic wave absorbing technology isof considerable importance as a viable countermeasureagainst intra-equipment interference. The use of electromagnetic wave absorbing sheets, for example, is known
to be very effective in shortening the developmental periods of digital equipment, making itself an essential designtechnology.
Today the electromagnetic wave absorbing sheets arewidely used in digital video cameras, digital cameras,
hard disk-based video recorders, mobile phones, notebook PCs, etc., thereby increasing technological awareness of the importance of the sheets.

3.

FEATURES OF F-CO TM SHEET EMI

Since F-CO TM Sheet EMI is not a silicone-relatedmaterial, it is siloxane-free thus presenting no problem

of contact faults for electronic equipment. Moreover, it isan environment-friendly material in compliance with theRoHS Directive coming into force in 2006.
Three types of F-CO TM Sheet EMI are currently available as described below.
3.1 EE/EMI TypeThe EE/EMI type is an electromagnetic wave absorbing
sheet combined with superior thermal conductivity. The
sheet is based on acrylic rubber compounded with aheat-conductive filler and a soft magnetic material, and
it is self-adhesive on one side while the other side is not
so, permitting ease of attachment. It is an environmentfriendly, halogen-free sheet with a thickness ranging
from 0.5 mm to 5 mm, and its material performance issuch that the electromagnetic wave absorbing property
is effective for a wide frequency range; the thermal
conductivity is 2 W/m·K and more, amply allowing
applications in the areas of high heat generation; and theflame retardance conforms to UL94 V-0.
Main applications are game machines and communications equipment for mobile phone base stations.

Photo 1F-CO TM Sheet EMI, EE/EMI type.

3.2 EMI Type
This product can be used in a wide frequency range, but
is especially effective in the high-frequency range of one
to some GHz.
The EMI type sheet is based on a polyolefin-related
polymer compounded with a soft magnetic material having a special granular shape, and achieves a highmechanical strength irrespective of its small thickness.
The product with a thickness of about 0.1 mm is available in long lengths thanks to a continuous production
method that takes advantage of our proprietary tape manufacturing technology. One side of the product is coated

Furukawa Review, No. 27

200584

Electromagnetic Wave Absorbing Sheet “F-CO TM Sheet EMI”

Table 1
Item

Characteristics of F-CO TM Sheet EMI.

EE/EMIEMI

EMI-4

Thickness (mm)

0.5~5

0.1~1

0.1~1

Thermal conductivity (W/m·K)

2.3

0.811×1010

1×109

1×109

Type

Volume resistivity (Ω-cm)
Breakdown voltage (kV/mm)

222

Flame retardance (UL94)

V-0

V-0 ~ HB

V-0 ~ HB

6075

75

Adhesion (N/25mm)

Self-adhesive on one side

Adhesive on one side

Adhesive on one side

Note

Halogen-free; High thermal
conductivity

Halogen-free grade / Ordinary
grade

Halogen-free; Electromagnetic wave absorbing
for low frequencies below some MHz

3.3 EMI-L TypeThe EMI-L type sheet can also be used in a wide
frequency range, but is especially effective in the lowfrequency range of below some MHz.
The product is based on a soft, halogen-free resin compounded with a proprietary soft magnetic material, and isprocessed into an environment-friendly thin sheet using
a special process which provides the product with theadvantage of the shape and composition of the magneticcomponent. Thus the product offers superior magnetic
characteristics in terms of permeability and magnetic
attenuation, realizing a sufficient noise reduction effect inthe sub-MHz range as illustrated in Figure 1.
Main applications are digital home appliances in general, digital video cameras, digital cameras, hard diskbased video recorders, mobile phones and notebookPCs.

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Main applications are digital video cameras, digitalcameras and mobile terminals.

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Figure 1 Noise reduction effects of the sheet.

Photo 24.

F-CO TM Sheet EMI, EMI type and EMI/EMI-L type.

CONCLUSIONS

We intend to promote hereafter the development ofelectromagnetic wave absorbing sheet in response todiversified customers' needs. We are ready to offer ourdevelopment proposals for any requirements concerning
EMI-resistant sheet not covered in the description
presented here. So, please feel free to contact us.

For more information, please contact:
Thermal and Antenna Solutions Dept., Electronics
Components Div., Electronics and Automotive Systems
Co.
TEL: +81-463-24-9784
FAX: +81-463-24-9786
orR&D Div., F-CO
TEL: +81-463-21-4873
FAX: +81-463-21-5509

Furukawa Review, No. 27

200585