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IEC 61747-40-1
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
Liquid crystal display devices –
Part 40-1: Mechanical testing of display cover glass for mobile devices –
Guidelines
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IEC 61747-40-1
Edition 2.0 2019-04
INTERNATIONAL
STANDARD
Liquid crystal display devices –
Part 40-1: Mechanical testing of display cover glass for mobile devices –
Guidelines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120 ISBN 978-2-8322-6800-1
– 2 – IEC 61747-40-1:2019 IEC 2019
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Mechanical performance testing guidelines . 7
4.1 General . 7
4.2 Mechanical testing guidelines for display cover glass for mobile devices . 8
5 Brief overview of mechanical test methods . 9
5.1 Edge strength . 9
5.2 Surface impact resistance (energy-to-failure) . 9
5.3 Surface strength . 9
5.4 Resistance against sharp contact surface damage and propagation under
rigid support (energy-to-failure) . 9
5.5 Retained surface strength . 10
Bibliography . 11
Table 1 – Comprehensive list of cover glass testing methods . 8
Table 2 – Matrix of cover glass test methods and glass condition . 9
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LIQUID CRYSTAL DISPLAY DEVICES –
Part 40-1: Mechanical testing of display cover glass
for mobile devices – Guidelines
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,
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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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International Standard IEC 61747-40-1 has been prepared by IEC technical committee 110:
Electronic displays.
This second edition cancels and replaces the first edition published in 2013. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) withdrawal of test methods unsuitable for mobile display cover,
b) revision of test methods based on newly developed market relevance,
c) addition of test method for abraded strength,
d) addition of explanations about the relevance between the test methods and the fracture
mode, and
– 4 – IEC 61747-40-1:2019 IEC 2019
e) revision of terms and definitions.
The text of this International Standard is based on the following documents:
CDV Report on voting
110/1040/CDV 110/1093/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
A list of all parts in the IEC 61747 series, published under the general title Liquid crystal
display devices, can be found on the IEC website.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
INTRODUCTION
Mobile electronic devices have become increasingly sophisticated and often incorporate
displays for the purposes of user interface and viewing. Such displays commonly incorporate
a transparent cover glass which aids in protecting the display against the introduction of
damage through routine device transport and use, as well as occasional or accidental misuse.
The purpose of this document is to provide mechanical testing guidelines for cover glasses
used in such applications. Such glasses can be strengthened or not, for example via an ion-
exchange process, which acts to increase mechanical strength through the introduction of a
surface compressive layer.
It is assumed that all measurements – described in detail in individual test method standards
– are performed by personnel skilled in the general art of mechanical property measurements.
Furthermore, it is recommended that all equipment is suitably calibrated as is known to skilled
personnel and that records of the calibration data and traceability are kept.
– 6 – IEC 61747-40-1:2019 IEC 2019
LIQUID CRYSTAL DISPLAY DEVICES –
Part 40-1: Mechanical testing of display cover glass
for mobile devices – Guidelines
1 Scope
This part of IEC 61747 provides mechanical performance testing guidelines for cover glass
used in electronic flat panel displays in mobile devices. This document focuses on key
mechanical testing performance parameters and covers mainly strength and damage
resistance attributes. The test methods focus on the cover glass level testing only.
NOTE The glass used for cover glasses for electronic mobile devices can be chemically strengthened by an ion-
exchange process. This ion exchange process increases the mechanical strength of the glass.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
abraded
subjected to a defined process which introduces mechanical abrasive damage to a portion of
the specimen to be placed under tension during subsequent flexural strength testing
EXAMPLE Biaxial flexure via ring-on-ring.
3.2
as-received
representative of standard sample preparation and handling practices, and therefore free of
intentional mechanical damage such as abrasion, scratching, or indentation
Note 1 to entry: The strength of glass is not an intrinsic material property, and like other brittle elastic materials,
is highly dependent upon the surface flaw population. The term “as-received” is meant to represent the surface
condition upon specimen receipt and is distinguished from a condition where damage has been intentionally
introduced prior to testing.
3.3
central tension
CT
tensile stress generated within the interior of a glass article which serves to counteract (i.e.,
force balance) compressive stress acting at or near the article surface
3.4
chemically strengthened
subjected to a molten salt bath containing alkali ions typically larger than those residing in the
glass, resulting in the generation of residual compressive stress (3.5) and central tension (3.3)
3.5
compressive stress
CS
maximum residual stress in compression measured near the glass surface
3.6
cover glass
glass that typically protects an optical component such as a display from damage
3.7
damage resistance
ability to resist certain potential damage-inducing events such as abrasion
3.8
edge strength
measured stress at failure in the case where failure is known to have originated from a
specimen edge
3.9
mobile device
electronic device that includes a battery and is designed to be carried about
...