IEC 60749-24:2025

IEC 60749-24 ®
Edition 2.0 2025-11
INTERNATIONAL
STANDARD
REDLINE VERSION
Semiconductor devices - Mechanical and climatic test methods -
Part 24: Accelerated moisture resistance - Unbiased HAST
ICS 31.080.01 ISBN 978-2-8327-0915-3
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.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
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 - IEC Products & Services Portal - products.iec.ch
webstore.iec.ch/advsearchform Discover our powerful search engine and read freely all the
The advanced search enables to find IEC publications by a publications previews, graphical symbols and the glossary.
variety of criteria (reference number, text, technical With a subscription you will always have access to up to date
committee, …). It also gives information on projects, content tailored to your needs.
replaced and withdrawn publications.
Electropedia - www.electropedia.org
The world's leading online dictionary on electrotechnology,
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published containing more than 22 500 terminological entries in English
details all new publications released. Available online and and French, with equivalent terms in 25 additional languages.
once a month by email. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer
Service Centre: sales@iec.ch.
CONTENTS
FOREWORD . 2
1 Scope and object . 4
2 Normative references . 4
3 Terms and definitions . 4
4 GeneralTest requirements . 4
5 Test apparatus . 5
5.1 Test chamber . 5
5.2 Records . 5
5.3 Devices under stress . 5
5.4 Ionic contamination . 5
5.5 Distilled or deionized water . 5
6 Test conditions . 5
7 Procedure . 6
7.1 Mounting . 6
7.2 Ramp-up . 6
7.3 Ramp-down . 7
7.4 Test clock . 7
7.5 Electrical tests . 7
7.6 Handling . 7
8 Failure criteria . 7
9 Safety . 7
10 Summary . 8
Bibliography . 9

Table 1 – Temperature, relative humidity, and pressure Test conditions for accelerated
moisture resistance testing . 6

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Semiconductor devices - Mechanical and climatic test methods -
Part 24: Accelerated moisture resistance - Unbiased HAST

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of patens, which may
be required to implement this document. However, implementers are cautioned that this may not represent the
latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC shall
not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 60749-24:2004. 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 60749-24 has been prepared by IEC technical committee 47: Semiconductor devices. It is
an International Standard.
This second edition, cancels and replaces the first edition published in 2004. lt is based on
JEDEC document JESD22-A118B.01. It is used with permission of the copyright holder, JEDEC
Solid State Technology Association. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) rearrangement of clauses to reposition requirements;
b) addition of two notes to the post-test electrical procedures.
The text of this International Standard is based on the following documents:
Draft Report on voting
47/2957/FDIS 47/2974/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.
A list of all parts of the IEC 60749 series, under the general title Semiconductor devices –
Mechanical and climatic test methods, can be found in the IEC website.
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 and object
This part of IEC 60749 specifies unbiased highly accelerated stress testing (HAST). HAST is
performed for the purpose of evaluating the reliability of non-hermetically packaged solid-state
devices in humid environments.
It is a highly accelerated test which employs temperature and humidity under non-condensing
conditions to accelerate the penetration of moisture through the external protective material
(encapsulant or seal) or along the interface between the external protective material and the
metallic conductors which pass through it. Bias is not applied in this test to ensure that the
failure mechanisms potentially overshadowed by bias can be uncovered (e.g. galvanic
corrosion).
This test is used to identify failure mechanisms internal to the package and is destructive.
NOTE This test is a complete rewrite of the test contained in Clause 4C of Chapter 3 of IEC 60749 (1996) (without
bias voltage).
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 60749-5, Semiconductor devices - Mechanical and climatic test methods - Part 5: Steady-
state temperature humidity bias life test
IEC 60749-33, Semiconductor devices - Mechanical and climatic test methods - Part 33:
Accelerated moisture resistance - Unbiased autoclave
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– ISO Online browsing platform: available at https://www.iso.org/obp
– IEC Electropedia: available at https://www.electropedia.org
4 GeneralTest requirements
This test method applies primarily to moisture resistance evaluations and robustness testing
and may be used as an alternative to unbiased autoclave.
Samples are subjected to a non-condensing, humid atmosphere, as described in IEC 60749-33,
but with a higher temperature and without bias. For the temperature limits defined by this
procedure, the test will typically generate the same failure mechanisms as those in an unbiased
autoclave "85 °C/85 % RH" steady-state humidity life test, but caution should be exercised if
higher temperatures are considered, since non-realistic failure modes can be generated. In the
case where both this test and that of IEC 60749-33 are performed, the results of this unbiased
HAST test takes precedence over the results of the unbiased autoclave test.
-------------
...