Ferrites and accessories
Cautions and warnings
Cautions and warnings
Mechanical stress and mounting
Ferrite cores have to meet mechanical requirements during assembling and for a growing number
of applications. Since ferrites are ceramic materials one has to be aware of the special behavior
under mechanical load.
As valid for any ceramic material, ferrite cores are brittle and sensitive to any shock, fast tempera-
ture changing or tensile load. Especially high cooling rates under ultrasonic cleaning and high static
or cyclic loads can cause cracks or failure of the ferrite cores.
For detailed information see data book, chapter
“General - Definitions, 8.1”.
Effects of core combination on A
L
value
Stresses in the core affect not only the mechanical but also the magnetic properties. It is apparent
that the initial permeability is dependent on the stress state of the core. The higher the stresses are
in the core, the lower is the value for the initial permeability. Thus the embedding medium should
have the greatest possible elasticity.
For detailed information see data book, chapter
“General - Definitions, 8.1”.
Heating up
Ferrites can run hot during operation at higher flux densities and higher frequencies.
NiZn-materials
The magnetic properties of NiZn-materials can change irreversible in high magnetic fields.
Ferrite Accessories
EPCOS ferrite accessories have been designed and evaluated only in combination with EPCOS
ferrite cores. EPCOS explicitly points out that EPCOS ferrite accessories or EPCOS ferrite cores
may not be compatible with those of other manufacturers. Any such combination requires prior te-
sting by the customer and will be at the customer‘s own risk.
EPCOS assumes no warranty or reliability for the combination of EPCOS ferrite accessories with
cores and other accessories from any other manufacturer.
Processing remarks
The start of the winding process should be soft. Else the flanges may be destroyed.
– Too strong winding forces may blast the flanges or squeeze the tube that the cores can not be
mounted any more.
– Too long soldering time at high temperature (>300 °C) may effect coplanarity or pin arrange-
ment.
– Not following the processing notes for soldering of the J-leg terminals may cause solderability
problems at the transformer because of pollution with Sn oxyde of the tin bath or burned insula-
tion of the wire. For detailed information see chapter
“Processing notes”,
section 2.2.
– The dimensions of the hole arrangement have fixed values and should be understood as
a recommendation for drilling the printed circuit board. For dimensioning the pins, the group
of holes can only be seen under certain conditions, as they fit into the given hole arrangement.
To avoid problems when mounting the transformer, the manufacturing tolerances for positioning
the customers’ drilling process must be considered by increasing the hole diameter.
Please read
Cautions and warnings
and
Important notes
at the end of this document.
3
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Ferrites and accessories
Cautions and warnings
Display of ordering codes for EPCOS products
The ordering code for one and the same product can be represented differently in data sheets,
data books, other publications and the website of EPCOS, or in order-related documents such as
shipping notes, order confirmations and product labels.
The varying representations of the
ordering codes are due to different processes employed and do not affect the
specifications of the respective products.
Detailed information can be found on the Internet
under www.epcos.com/orderingcodes.
Please read
Cautions and warnings
and
Important notes
at the end of this document.
4
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Ferrites and accessories
Symbols and terms
Symbols and terms
Symbol
A
A
e
A
L
A
L1
A
min
A
N
A
R
B
ΔB
ˆ
B
ˆ
ΔB
B
DC
B
R
B
S
C
0
CDF
DF
d
E
a
f
f
cutoff
f
max
f
min
f
r
f
Cu
g
H
ˆ
H
H
DC
H
c
h
h/μ
i
2
I
I
DC
ˆ
I
J
k
k
3
k
3c
L
Meaning
Cross section of coil
Effective magnetic cross section
Inductance factor; A
L
= L/N
2
Minimum inductance at defined high saturation (
μ
a
)
Minimum core cross section
Winding cross section
Resistance factor; A
R
= R
Cu
/N
2
RMS value of magnetic flux density
Flux density deviation
Peak value of magnetic flux density
Peak value of flux density deviation
DC magnetic flux density
Remanent flux density
Saturation magnetization
Winding capacitance
Core distortion factor
Relative disaccommodation coefficient DF = d/μ
i
Disaccommodation coefficient
Activation energy
Frequency
Cut-off frequency
Upper frequency limit
Lower frequency limit
Resonance frequency
Copper filling factor
Air gap
RMS value of magnetic field strength
Peak value of magnetic field strength
DC field strength
Coercive field strength
Hysteresis coefficient of material
Relative hysteresis coefficient
RMS value of current
Direct current
Peak value of current
Polarization
Boltzmann constant
Third harmonic distortion
Circuit third harmonic distortion
Inductance
5
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Unit
mm
2
mm
2
nH
nH
mm
2
mm
2
μΩ
= 10
–6
Ω
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
F = As/ V
mm
–4.5
J
s
–1
, Hz
s
–1
, Hz
s
–1
, Hz
s
–1
, Hz
s
–1
, Hz
mm
A/m
A/m
A/m
A/m
10
–6
cm/A
10
–6
cm/A
A
A
A
Vs/m
2
J/K
H = Vs/A
Please read
Cautions and warnings
and
Important notes
at the end of this document.
PCB Design
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