14th Edition
1
Table of Contents
Quality Policy Statement .......................................................................................................................................................... I.F.C.
Introduction ..................................................................................................................................................................................... 2
Magnetic Properties of Fair-Rite Materials ................................................................................................................................... 4
Fair-Rite Materials ......................................................................................................................................................................... 6
Board Components
24
29
41
50
74
78
84
Engineering Kits
....................................................................................................................................................
92
EMI Suppression Beads ................................................................................................................................................
Beads on Leads .............................................................................................................................................................
SM Beads .......................................................................................................................................................................
Chip Beads ....................................................................................................................................................................
PC Beads .......................................................................................................................................................................
Wound Beads ................................................................................................................................................................
Multi-Aperture Cores .....................................................................................................................................................
Cable Components
Round Cable EMI Suppression Cores ......................................................................................................................... 94
Split Round Cable EMI Suppression Cores ................................................................................................................. 98
Round Cable Snap-its ................................................................................................................................................. 102
Flat Cable EMI Suppression Cores ............................................................................................................................ 108
Flat Cable Snap-its ...................................................................................................................................................... 116
Miscellaneous Suppression Cores ............................................................................................................................. 118
Connector Suppression Plates ................................................................................................................................... 120
Tiles .............................................................................................................................................................................. 125
Inductive Components
Open Magnetic Circuit
Rods .............................................................................................................................................................. 129
RFID .............................................................................................................................................................. 132
Tack Bobbin Cores ....................................................................................................................................... 133
Bobbins ......................................................................................................................................................... 134
Closed Magnetic Circuit
Toroids .......................................................................................................................................................... 136
Pot Cores ...................................................................................................................................................... 142
E & I Cores .................................................................................................................................................... 146
ETD Cores ..................................................................................................................................................... 150
U Cores ......................................................................................................................................................... 152
PQ Cores ....................................................................................................................................................... 154
EP Cores ....................................................................................................................................................... 156
85 Material Toroids ....................................................................................................................................... 158
References
Reference Tables ........................................................................................................................................................ 159
Soft Ferrite References ................................................................................................................................................ 160
Glossary of Terms ........................................................................................................................................................ 162
Magnetic Design Formulas ......................................................................................................................................... 163
Wire Table of Copper Magnet Wire ............................................................................................................................ 164
Technical Articles
The Effect of Direct Current on the Inductance of a Ferrite Core ............................................................................... 165
Use of Ferrites in Broadband Transformers ............................................................................................................... 170
How to Choose Ferrite Components for EMI Suppression ........................................................................................ 174
Ferrite Tile Absorbers for EMC Test Chamber Applications ...................................................................................... 183
Numerical Index ....................................................................................................................................................................... 186
Copyright
©
2001 by Fair-Rite Products Corp.
All rights reserved. No part of the contents of this book may be published or transmitted in any form or by any means
without the expressed written permission of the publisher.
P.O. Box J,One Commercial Row, Wallkill, NY 12589-0288
Phone: (888) FAIR RITE / (845) 895-2055
(888) 324-7748
Fair-Rite Products Corp.
•
FAX: (888) FERRITE / (845) 895-2629 • www.fair-rite.com • E-Mail: ferrites@fair-rite.com
(888) 337-7483
Note: (914) Area Code has changed to (845).
2
14th Edition
Introduction
History
The history of magnetism began with the discovery of the prop-
erties of a mineral called magnetite (Fe
3
O
4
). The most plentiful
deposits were found in the district of Magnesia in Asia Minor
(hence the mineral’s name) where it was observed, centuries
before the birth of Christ, that these naturally occurring stones
would attract iron. Later on it found application in the lodestone
of early navigators. In 1600 William Gilbert published
De Magnete,
the first scientific study on magnetism. In 1819 Hans Christian
Oersted observed that an electric current in a wire affected a
magnetic compass needle, thus with later contributions by Fara-
day, Maxwell, Hertz and others, the new science of electromag-
netism came into being.
Even though the existence of naturally occurring magnetite, a
weak type of hard ferrite, had been known since antiquity,
producing an analogous soft magnetic material in the laboratory
proved elusive. Research on magnetic oxides was going on
concurrently during the 1930’s, primarily in Japan and the
Netherlands. However, it was not until 1945 that J. L. Snoek of
the Philips’ Research Laboratories in the Netherlands suc-
ceeded in producing a soft ferrite
*
material for commercial
applications.
Fair-Rite Products Corp. was not far behind in the manufacture
and sale of soft ferrites for use in the electronics industry. It was
formed in 1952 and officially started operations in 1953. The
ensuing years have seen a rather crude product, which was
available in only a few shapes and materials, develop into a
major line of ferrite components for inductive devices, produced
in many core configurations with a wide selection of materials.
The application of ferrites in EMI suppression as shield beads
and broadband chokes, where an effective resistive impedance
is produced at high frequencies, has grown so fast in the last
decade, that their use as EMI suppressors is limited only by the
imagination of the end user.
During the last 50 years the basic constituents of ferrites have
changed little, but purity of raw materials and process control
have improved dramatically. Ferrites are ceramic materials with
the general chemical formula MO.Fe
2
O
3
, where MO is one or
more divalent metal oxides blended with 48 to 60 mole percent
of iron oxide. Fair-Rite manufactures three broad groups of soft
ferrite materials:
Manganese zinc (Fair-Rite 31, 33, 73, 75, 76, 77 and 78 material)
Nickel zinc (Fair-Rite 42, 43, 44, 51, 61, 67 and 68 material)
Manganese (Fair-Rite 85 material)
Manganese zinc ferrites are completely vitrified and have very
low porosity. They have the highest permeabilities and exhibit
volume resistivities ranging from one hundred to several thou-
sand ohm-centimeter. Manganese zinc ferrite components are
used in tuned circuits and magnetic power designs from the low
kilohertz range into the broadcast spectrum. These ferrites have
a linear expansion coefficient of approximately 10 ppm/
o
C.
The nickel zinc ferrites vary in porosity, and frequently contain
oxides of other metals, such as those of magnesium, man-
ganese, copper or cobalt. Volume resistivities range from sev-
eral kilohm-centimeter to tens of megohm-centimeter. In gener-
al, they are used at higher frequencies (above 1 MHz), and are
suitable for low flux density applications. Nickel zinc ferrites have
a linear expansion coefficient of approximately 8 ppm/
o
C.
The manganese ferrite is a dense, temperature stable material
displaying a high degree of squareness in its hysteresis loop.
This makes this material uniquely suited for such applications as
multiple output control in switched-mode power supplies and
high frequency magnetic amplifiers.
As is evident from the flow diagram on page 3, there is consid-
erable processing involved, and the manufacturing cycle will
take a minimum of two weeks. The parts listed in the catalog
represent a broad cross section of the wide variety of cores
produced by Fair-Rite Products. Large OEM quantitites are
manufactured by Fair-Rite to order. Most of the more commonly
used parts are stocked by our distributors, offering prompt
deliveries. For a complete listing of our distributors visit our site
on the Internet at www.fair-rite.com.
Many of the parts produced by Fair-Rite are made to customer
specifications, and we welcome inquiries involving application-
specific designs. We have the capability to design tooling rapidly,
and have it fabricated either by our own tool shop or by outside
vendors.
Soft Ferrites
The single most important characteristic of soft ferrites, as com-
pared to other magnetic materials, is the high volume resistivity
exhibited in the monolithic form. Since eddy current losses are
inversely proportional to resistivity and these losses increase
with the square of the frequency, high resistivity becomes an
essential factor in magnetic materials intended for high fre-
quency operation. The magnetic properties of ferrite components
are isotropic, and by employing various pressing, injection
molding, and/or grinding techniques, a wide range of complex
shapes can be formed. There is no other class of magnetic
material that can match soft ferrites in performance, cost and
volumetric efficiency, over the range from audio frequencies to
above 500 MHz.
*Footnote:
The difference between hard and soft ferrite is not tactile, but rather a magnetic characteristic.
Soft ferrite does not retain significant magnetization, whereas hard ferrite magnetization is considered permanent.
Fair-Rite Products Corp.
Phone: (888) FAIR RITE / (845) 895-2055
(888) 324-7748
P.O. Box J,One Commercial Row, Wallkill, NY 12589-0288
•
FAX: (888) FERRITE / (845) 895-2629 • www.fair-rite.com • E-Mail: ferrites@fair-rite.com
(888) 337-7483
Note: (914) Area Code has changed to (845).
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