IEC 61332:2026

IEC 61332 ®
Edition 4.0 2026-01
INTERNATIONAL
STANDARD
REDLINE VERSION
Soft ferrite material classification
ICS 29.100.10 ISBN 978-2-8327-1022-7
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CONTENTS
FOREWORD . 2
1 Scope . 1
2 Normative references . 4
3 Terms and definitions . 4
4 Classification . 4
4.1 Material classification . 4
4.2 Main classes . 5
4.3 Subclasses . 5
5 Soft ferrite material classes . 5
5.1 Materials used as impedances in interference suppression applications (IS
class) . 5
5.2 Materials used mainly in low flux density applications (B ≤ 5 mT) (SP class) . 6
5.3 Materials used mainly in high flux density applications (PW class) . 6
Bibliography . 8

Table 1 – IS class ferrite materials . 5
Table 2 – SP class ferrite materials . 6
Table 3 – PW class ferrite materials . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Soft ferrite material classification

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 61332:2016. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 61332 has been prepared by IEC technical committee 51: Magnetic components, ferrite
and magnetic powder materials. It is an International Standard.
This fourth edition cancels and replaces the third edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) added PW2c and PW3c in subclasses PW2 and PW3 respectively in Table 3;
b) added the column of B in Table 3;
S
c) added a smaller size of the test core (Ø 12,7 mm × Ø 7,5 mm × 7 mm) for higher measuring
frequency (≥ 500 kHz) in Table 3.
The text of this International Standard is based on the following documents:
Draft Report on voting
51/1582/FDIS 51/1591/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
1 Scope
This document specifies classification rules for soft ferrite materials used in inductive
components (inductors and transformers) fulfilling the requirements of the electronic industries.
This document addresses the following issues for ferrite suppliers and users:
– cross-reference between materials from multiple suppliers;
– assistance to customers users in understanding the published technical data in catalogues
when comparing multiple suppliers;
– guidance to customers users in selecting the most applicable material for each application;
– setting of nomenclature for IEC standards relating to ferrite;
– establishing uniformed benchmarks for suppliers for performance in new development of
materials.
The numerical values given in this document are typical values of the parameters (properties)
of the related materials. Direct translation from the material specification into the core
specification is not always easy or possible.
Every detailed material and core specification should be agreed upon between the user
suppliers and the manufacturer users.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-221, International Electrotechnical Vocabulary (IEV) - Part 221: Magnetic materials
and components
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-221 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
4 Classification
4.1 Material classification
Soft ferrite materials may be classified according to the following basic parameters:
– initial permeability and relevant operation frequency and/or applicable maximum frequency;
– initial permeability as a function of the temperature;
– applicable maximum flux density and/or amplitude permeability;
– power loss at a given frequency, temperature and flux density;
– normalized impedance at a given frequency.
4.2 Main classes
Soft ferrite materials may can be divided into three main classes identified by two letters as
follows:
– class IS materials are for use at AC low flux density as impedances in interference
suppression (EMI) applications;
– class SP materials are for use at low flux density in signal processing applications;
– class PW materials are for use at high flux density (power application).
4.3 Subclasses
Each main class is divided into subclasses identified by two letters and a serial number.
Ferrite manufacturers’ suppliers' catalogues may indicate more than one class into which a
material grade can fall, where desired.
5 Soft ferrite material classes
5.1 Materials used as impedances in interference suppression applications (IS class)
These materials are mainly used in the shape of rods, tubes, beads, wide band chokes, bobbin
cores, SQ-cores and rings ring-cores. The relevant subclasses are given in Table 1.
Table 1 – IS class ferrite materials
Normalized Initial
a
Subclasses Frequency Curie temperature
b c
impedance permeability
Z μ T
N i C
MHz Ω/mm °C
IS1 300 ≥ 50 < 100 > 300
IS2a ≥ 50
300 100 to 2 000 200 to 300
IS2b ≥ 40
IS3a ≥ 40
100 100 to 2 000 100 to 250
IS3b ≥ 30
IS4a ≥ 30
30 100 to 2 000 100 to 250
IS4b ≥ 20
IS5a ≥ 30
10 2 000 to 6 000 100 to 250
IS5b ≥ 20
IS6a ≥ 30
3 2 000 to 6 000 100 to 150
IS6b ≥ 20
IS7a ≥ 20
1 2 000 to 6 000 100 to 150
IS7b ≥ 10
IS8a ≥ 20
1 6 000 to 10 000 100 to 150
IS8b ≥ 10
IS9a ≥ 10
0,5 10 000 to 15 000 > 100
IS9b ≥ 5
a
The frequency is the measuring frequency of the normalized impedance.
b
Measured on a bead Ø 5 mm × Ø 2 mm × 10 mm and at temperature of 25 °C.
c
μ is measured at ≤ 10 kHz, ≤ 0,5 mT. μ is for reference only, indicating typical values seen. μ is not a

i i i
fundamental parameter for class IS materials.

5.2 Materials used mainly in low flux density applications (B ≤ 5 mT) (SP class)
These materials are mainly used in the shape of ring-cores, pot-cores, EP-cores, RM-cores and
E-cores. The relevant subclasses are given in Table 2.
Table 2 – SP class ferrite materials
Initial Relative loss
b
Subclasses Frequency Curie temperature
a a
permeability factor
tanδ/μ T
i C
–6
μ MHz °C
×10
i
SP1 < 100 50 to 150 10 > 300
SP2 100 to 400 20 to 30 1 > 250
SP3 400 to 800 15 to 50 0,1 > 150
SP4 800 to 1 200 1 to 10 0,1 > 120
SP5 1 200 to 2 000 1 to 10 0,1 > 120
SP6 1 200 to 2 500 2 to 7 0,1 > 150
SP7 1 500 to 2 500 3 to 5 0,1 > 150
SP8 2 500 to 3 500 2 to 10 0,1 > 130
SP9 3 500 to 6 000 ≤ 15 0,1 > 120
SP10a 6 000 to 8 000 ≤ 3 0,01 > 120
SP10b 6 000 to 8 000 ≤ 10 0,01 > 120
SP11a 8 000 to 12 000 ≤ 3 0,01 > 100
SP11b 8 000 to 12 000 ≤ 10 0,01 > 100
SP12a 12 000 to 16 000 ≤ 6 0,01 > 100
SP12b 12 000 to 16 000 ≤ 20 0,01 > 100
SP13 16 000 to 20 000 ≤ 20 0,01 > 100
NOTE The size of the test core is Ø 10 mm × Ø 6 mm × 4 mm.
a
μ and tanδ/μ are measured at 25 °C.

i i
b
The frequency is the measuring frequency for tanδ/μ .
i
5.3 Materials used mainly in high flux density applications (PW class)
These materials are mainly used in the shape of RM-cores, EFD-cores, EREC-cores, ETD-cores,
EER-cores, E-cores, PQ-cores, PM-cores, U-cores, ring-cores and cores for planar applications.
The relevant subclasses are given in Table 3.
Table 3 – PW class ferrite materials
Power loss
Performance
(volume)
a c d gh
c,d b
Subclasses f T μ B factor μ
f B
max a S i
Density
(B × f)
d,e,f,g
kHz kHz mT °C mT Mt × kHz
kW/m
3 500
PW1a 4 500 ≤ 100
to
100 15 300 100 2 500 -
PW1b (300 × 15) ≤ 200
2 000
3 500
PW2a - ≤ 60
5 000
to
PW2b 200 25 200 100 2 500 - ≤ 150
2 000
(200 × 25)
PW2c ≥ 470 ≤ 300
1 400
PW3a 100 - ≤ 350
3 500
PW3b 100 - 20 000 ≤ 700
to
300 100 200 3 000
PW3c 100 ≥ 440 (200 × 100) ≤ 425 2 000
1 400
PW3a-wide 80 to 140 - ≤ 450
PW4a 100 ≤ 350 3 000
30 000
PW4b 500 300 100 100 3 000 - ≤ 700 to
(100 × 300)
PW4a-wide 60 to 120 ≤ 350 1 400
PW5a 100 ≤ 100 2 000
25 000
PW5b 1 000 500 50 100 2 000 - ≤ 150 to
(50 × 500)
PW5a-wide 60 to 120 ≤ 150 1 400
1 400
PW6a 25 000 ≤ 100
2 000 1 000 25 100 1 000 - to
PW6b (25 × 1 000) ≤ 150
1 400
PW7a 30 000 ≤ 100
3 000 2 000 15 100 1 000 - to
PW7b (15 × 2 000) ≤ 150
PW8a 30 000 ≤ 100
5 000 3 000 10 100 400 - to
PW8b (10 × 3 000) ≤ 200
PW9a 50 000 ≤ 200
10 000 5 000 10 100 40 - to
PW9b (10 × 5 000) ≤ 300
NOTE The size of the test core is Ø 25 mm × Ø 15 mm × 10 mm or smaller for measuring frequency lower than
500 kHz, and is Ø 12,7 mm × Ø 7,5 mm × 7 mm for 500 kHz and above.
a
f is the guide of applicable maximum frequency relevant to a given material subclass.
max
b
B is the applicable AC peak flux density relevant to a given material subclass. These levels of B normally result in
power losses in the ranges ≤ 300 kW/m , except for subclasses PW3 and PW4. In these ranges a wide variety of
sizes in the common shapes can be used in open air conditions without forced cooling. The use of higher flux
densities in these subclasses will result in higher power losses which may often require additional cooling, or will
be limited in open air with no forced cooling to the use of only smaller sizes from the common core shapes.
c
μ is the amplitude permeability at the conditions of T, B and f in Table 3. μ is for reference only.
a a
d
B is the saturation magnetic flux density at the temperature 100 °C and the magnetic field strength from 1 200 A/m
S
to 20 000 A/m (refer to IEC 60401-3:2015, Table 2). The cross-sectional area for calculating B should be actual
S
cross-sectional area of the test core.
de
Power loss should be measured at the conditions of T, B and f in Table 3. These combinations of B and f are
different than the preferred combinations according IEC 60401-3:2015, Table 2, where higher power losses than
300 kW/m are assumed as we
...