IEC 60539-2:2019

Directly heated negative temperature coefficient thermistors - Part 2: Sectional specification - Surface mount negative temperature coefficient thermistors

IEC 60539-2:2019 is applicable to surface mount directly heated negative temperature coefficient thermistors, typically made from transition metal oxide materials with semiconducting properties. These thermistors have metallized connecting pads or soldering strips and are intended to be mounted directly on to substrates for hybrid circuits or on to printed boards.
This edition includes the following significant technical changes with respect to the previous edition:
a) revision for the structure in accordance with ISO/IEC Directives, Part 2:2016 (seventh edition) to the extent practicable, and for harmonizing with IEC 60539-1:2016;
b) the upper category temperatures of 175 °C, 200 °C, 250 °C, 315 °C, 400 °C in Table 1 have been added;
c) the dimensions of 0402M in Annex A have been added.

Thermistances à coefficient de température négatif à chauffage direct - Partie 2: Spécification intermédiaire - Thermistances à coefficient de température négatif pour montage en surface

L'IEC 60539-2:2019 s'applique aux thermistances à coefficient de température négatif à chauffage direct pour montage en surface, typiquement constituées de matériaux faits d'oxyde de métal de transition dotés de propriétés semi-conductrices. Ces thermistances sont équipées de contacts de connexion métallisés ou de bandes de brasure et sont destinées à être montées directement sur des substrats pour circuits hybrides ou sur des cartes imprimées.
La présente édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) révision de la structure conformément aux directives ISO/IEC, Partie 2:2016 (septième édition), dans la mesure du possible, et pour l'harmonisation avec l'IEC 60539-1:2016;
b) les températures maximales de catégorie 175 °C, 200 °C, 250 °C, 315 °C, 400 °C ont été ajoutées dans le Tableau 1;
c) les dimensions de 0402M à l'Annexe A ont été ajoutées.

General Information

• Status: Published
• Publication Date: 18-Jul-2019
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.040.30 - Thermistors
• Technical Committee: TC 40 - Capacitors and resistors for electronic equipment
• Drafting Committee: MT 60539-2 - TC 40/MT 60539-2
• Current Stage: PPUB - Publication issued
• Start Date: 26-Jul-2019
• Completion Date: 19-Jul-2019

Relations

• Revises: IEC 60539-2:2003/AMD1:2010 - Amendment 1 - Directly heated negative temperature coefficient thermistors - Part 2: Sectional specification - Surface mount negative temperature coefficient thermistors
• Effective Date: 05-Sep-2023
• Revises: IEC 60539-2:2003 - Directly heated negative temperature coefficient thermistors - Part 2: Sectional specification - Surface mount negative temperature coefficient thermistors
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60539-2 ®
Edition 2.0 2019-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Directly heated negative temperature coefficient thermistors –
Part 2: Sectional specification – Surface mount negative temperature coefficient
thermistors
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
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About the IEC
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International Standards for all electrical, electronic and related technologies.

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IEC 60539-2 ®
Edition 2.0 2019-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Directly heated negative temperature coefficient thermistors –

Part 2: Sectional specification – Surface mount negative temperature coefficient

thermistors
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.040.30 ISBN 978-2-8322-7199-5

– 2 – IEC 60539-2:2019 RLV  IEC 2019
CONTENTS
FOREWORD . 5
1 General .
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Information to be given in a detail specification . 8
4.1 General . 8
4.2 Outline drawing and dimensions . 8
4.3 Mounting . 8
4.4 Ratings and characteristics . 8
4.4.1 Particular characteristics . 8
4.4.2 Marking . 8
Terminology .
5 Preferred ratings and characteristics . 9
5.1 Tolerances on rated zero-power resistance . 9
5.2 Climatic categories . 9
6 Quality assessment procedures . 9
Primary stage of manufacture .
Structurally similar components .
Qualification approval procedures .
The manufacturer shall comply with 3.4 of IEC 60539-1. .
Quality conformance inspection .
Qualification approval on the basis of the fixed sample size procedure .
Quality conformance inspection .
Formation of inspection lots .
Test schedule .
Delayed delivery .
Assessment level .
7 Test and measurement procedures . 13
7.1 Mounting . 13
7.2 Drying and recovery . 13
7.2.1 Drying . 13
7.2.2 Recovery . 13
7.3 Visual examination and check of dimensions . 13
7.3.1 Visual examination . 13
7.3.2 Requirements . 14
7.3.3 Marking . 15
7.3.4 Dimensions . 16
7.4 Electrical tests . 16
7.4.1 Zero-power resistance . 16
7.4.2 B-value or resistance ratio . 16
7.4.3 Resistance/temperature characteristic . 16
7.5 Thermal tests . 17
7.5.1 Dissipation factor (δ) . 17
7.5.2 Thermal time constant by cooling after self-heating (τ ) . 17
c
7.6 Resistance to soldering heat . 17
7.6.1 General . 17
7.6.2 Initial measurement . 17
7.6.3 Test conditions . 17
7.6.4 Recovery . 18
7.6.5 Final inspection, measurements and requirements. 18
7.7 Solderability . 18
7.7.1 General . 18
7.7.2 Test conditions . 18
7.7.3 Recovery . 19
7.7.4 Final inspection, measurements and requirements. 19
7.8 Rapid change of temperature . 19
7.9 Thermal shock . 19
Climatic sequence.
Initial measurements .
Dry heat .
Damp heat (cyclic), first cycle .
Cold.
Damp heat (cyclic), remaining cycles .
Final measurements .
7.10 Damp heat, steady state . 21
7.11 Endurance . 21
7.11.1 Endurance at T and P . 21
3 max
7.11.2 Endurance at upper category temperature . 22
7.12 Shear (adhesion) test . 22
7.13 Substrate bending test . 22
7.14 Component solvent resistance . 22
7.15 Solvent resistance of marking . 22
Annex A (normative) Guide for the specification and coding of dimensions of surface

mount negative temperature coefficient thermistors . 23
Annex B (normative) Quality assessment procedure . 25
B.1 Primary stage of manufacture . 25
B.2 Structurally similar components . 25
B.3 Qualification approval procedures . 25
B.4 Quality conformance inspection . 25
B.4.1 General . 25
B.4.2 Qualification approval on the basis of the fixed sample size procedure . 25
B.5 Quality conformance inspection . 27
B.5.1 Formation of inspection lots . 27
B.5.2 Test schedule . 28
B.5.3 Delayed delivery . 28
B.5.4 Assessment level . 28

Figure 1 – Fault: fissure or defect . 14
Figure 2 – Fault: crack . 14
Figure 3 – Separation or delamination . 14
Figure 4 – Exposed electrodes . 15
Figure 5 – Principal faces . 15

– 4 – IEC 60539-2:2019 RLV  IEC 2019
Figure 6 – Principal terminations – Gull wing . 16
Figure 7 – Principal terminations – Round termination . 16
Figure A.1 – Dimensioni
...

IEC 60539-2 ®
Edition 2.0 2019-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Directly heated negative temperature coefficient thermistors –
Part 2: Sectional specification – Surface mount negative temperature coefficient
thermistors
Thermistances à coefficient de température négatif à chauffage direct –
Partie 2: Spécification intermédiaire – Thermistances à coefficient de
température négatif pour montage en surface
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

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IEC 60539-2 ®
Edition 2.0 2019-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Directly heated negative temperature coefficient thermistors –

Part 2: Sectional specification – Surface mount negative temperature coefficient

thermistors
Thermistances à coefficient de température négatif à chauffage direct –

Partie 2: Spécification intermédiaire – Thermistances à coefficient de

température négatif pour montage en surface

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.040.30 ISBN 978-2-8322-7098-1

– 2 – IEC 60539-2:2019  IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Information to be given in a detail specification . 7
4.1 General . 7
4.2 Outline drawing and dimensions . 7
4.3 Mounting . 7
4.4 Ratings and characteristics . 7
4.4.1 Particular characteristics . 7
4.4.2 Marking . 7
5 Preferred ratings and characteristics . 7
5.1 Tolerances on rated zero-power resistance . 7
5.2 Climatic categories . 8
6 Quality assessment procedures . 8
7 Test and measurement procedures . 8
7.1 Mounting . 8
7.2 Drying and recovery . 8
7.2.1 Drying . 8
7.2.2 Recovery . 8
7.3 Visual examination and check of dimensions . 8
7.3.1 Visual examination . 8
7.3.2 Requirements . 9
7.3.3 Marking . 10
7.3.4 Dimensions . 11
7.4 Electrical tests . 11
7.4.1 Zero-power resistance . 11
7.4.2 B-value or resistance ratio . 11
7.4.3 Resistance/temperature characteristic . 11
7.5 Thermal tests . 12
7.5.1 Dissipation factor (δ) . 12
7.5.2 Thermal time constant by cooling after self-heating (τ ) . 12
c
7.6 Resistance to soldering heat . 12
7.6.1 General . 12
7.6.2 Initial measurement . 12
7.6.3 Test conditions . 12
7.6.4 Recovery . 12
7.6.5 Final inspection, measurements and requirements. 12
7.7 Solderability . 13
7.7.1 General . 13
7.7.2 Test conditions . 13
7.7.3 Recovery . 13
7.7.4 Final inspection, measurements and requirements. 13
7.8 Rapid change of temperature . 13
7.9 Thermal shock . 13

7.10 Damp heat, steady state . 14
7.11 Endurance . 14
7.11.1 Endurance at T and P . 14
3 max
7.11.2 Endurance at upper category temperature . 15
7.12 Shear (adhesion) test . 15
7.13 Substrate bending test . 15
7.14 Component solvent resistance . 15
7.15 Solvent resistance of marking . 15
Annex A (normative)  Guide for the specification and coding of dimensions of surface
mount negative temperature coefficient thermistors . 16
Annex B (normative) Quality assessment procedure . 17
B.1 Primary stage of manufacture . 17
B.2 Structurally similar components . 17
B.3 Qualification approval procedures . 17
B.4 Quality conformance inspection . 17
B.4.1 General . 17
B.4.2 Qualification approval on the basis of the fixed sample size procedure . 17
B.5 Quality conformance inspection . 19
B.5.1 Formation of inspection lots . 19
B.5.2 Test schedule . 20
B.5.3 Delayed delivery . 20
B.5.4 Assessment level . 20

Figure 1 – Fault: fissure or defect . 9
Figure 2 – Fault: crack . 9
Figure 3 – Separation or delamination .
...