1、 IEC 62951-1 Edition 1.0 2017-04 INTERNATIONAL STANDARD Semiconductor devices Flexible and stretchable semiconductor devices Part 1: Bending test method for conductive thin films on flexible substrates IEC 62951-1:2017-04(en) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2017 IEC,
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11、emiconductor devices Part 1: Bending test method for conductive thin films on flexible substrates INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31.080.99 ISBN 978-2-8322-3896-7 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication
12、 from an authorized distributor. colour inside 2 IEC 62951-1:2017 IEC 2017 CONTENTS FOREWORD . 3 1 Scope 5 2 Normative references 5 3 Terms, definitions and symbols 5 3.1 Terms and definitions 5 3.2 Symbols and designations 6 4 Test piece . 7 4.1 Design of test piece 7 4.2 Preparation of a test piec
13、e 7 4.3 Measurement of dimensions . 7 4.4 Storage prior to testing . 8 5 Testing method and test apparatus 8 5.1 General . 8 5.2 Test apparatus 8 5.3 Measurement of electrical resistance 8 5.4 Test procedure 9 5.5 Observation of cracks in test piece . 9 5.6 Data analysis 9 5.7 Test environment 9 6 T
14、est report . 10 Annex A (informative) X-Y- bending test method 11 Annex B (informative) Data analysis: Calculation of bending radius and bending strain 13 B.1 Calculation of bending radius 13 B.2 Calculation of bending strain of the film 13 Bibliography 15 Figure 1 Shape of a test piece . 7 Figure 2
15、 Bending test apparatus 8 Figure A.1 X-Y- bending test method 11 Figure A.2 Schematic of the bending geometry in X-Y- system 12 Figure B.1 Geometrical shape of bent test piece 13 Table 1 Symbols and designations of a test piece 7 IEC 62951-1:2017 IEC 2017 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION
16、_ SEMICONDUCTOR DEVICES FLEXIBLE AND STRETCHABLE SEMICONDUCTOR DEVICES Part 1: Bending test method for conductive thin films on flexible substrates FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical
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27、 such patent rights. International Standard IEC 62951-1 has been prepared by IEC technical committee 47: Semiconductor devices. The text of this International Standard is based on the following documents: FDIS Report on voting 47/2369/FDIS 47/2384/RVD Full information on the voting for the approval
28、of this International Standard can be found in the report on voting indicated in the above table. This document has been drafted in accordance with the ISO/IEC Directives, Part 2. 4 IEC 62951-1:2017 IEC 2017 A list of all parts in the IEC 62951 series, published under the general title Semiconductor
29、 devices Flexible and stretchable semiconductor devices, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC website under “http:/webstore.iec.ch“ in the data related to the specific publ
30、ication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicates that it contains colours which are
31、 considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. IEC 62951-1:2017 IEC 2017 5 SEMICONDUCTOR DEVICES FLEXIBLE AND STRETCHABLE SEMICONDUCTOR DEVICES Part 1: Bending test method for conductive thin films on flexibl
32、e substrates 1 Scope This part of IEC 62951 specifies a bending test method to measure the electromechanical properties or flexibility of conductive thin films deposited or bonded on flexible non-conductive substrates. Conductive thin films on flexible substrates are extensively used in flexible ele
33、ctronic devices and flexible semiconductors. Conductive thin films include any films deposited or bonded onto a non-conductive flexible substrate such as thin metal film, transparent conducting electrode, and thin silicon film. The electrical and mechanical behaviours of thin films on flexible subst
34、rates differ from those of freestanding films and substrates due to their interfacial interactions and adhesion between the film and substrate. The object of this standard is to establish simple and repeatable test methods for evaluating the electromechanical properties or flexibility of conductive
35、thin films on flexible substrate. The bending test methods include outer bending test and inner bending test. 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, on
36、ly the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 62047-2:2006, Semiconductor devices Micro-electromechanical devices Part 2: Tensile testing method of thin film materials IEC 62047-22:2014, Semiconductor devic
37、es Micro-electromechanical devices Part 22: Electromechanical tensile test method for conductive thin films on flexible substrates 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminologi
38、cal 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 3.1.1 bending radius of curvature r radius of curvature that the test piece shows in bending test 6 IEC 629
39、51-1:2017 IEC 2017 3.1.2 critical bending radius bending radius at which the electrical resistance starts to exceed a predefined limit, and/or fracture of the film caused by delamination or initiation of the cracks occurs Note 1 to entry: It is the minimum bending radius that conductive thin films c
40、an tolerate. 3.1.3 nominal bending strain e strain in the center of the bent test piece in the bending direction Note 1 to entry: Generally it is referred to the strain at the top of the bent film on flexible substrate. 3.1.4 flexible substrate substrate with flexibility onto which conductive thin f
41、ilms will be deposited, bonded or attached 3.1.5 gauge factor G Fratio of the change in electrical resistance divided by the original resistance (R O , resistance in the undeformed configuration) to nominal bending strain (e) Note 1 to entry: Gauge factor is expressed as G F= (R R O )/ R O e, where
42、R is the electrical resistance in the deformed configuration. SOURCE: IEC 62047-22: 2014, 3.1.1, modified The word “engineering“ has been replaced by “nominal bending“ in the definition. 3.1.6 outer bending test outward bending test face-out bending test convex bending test test, where the test piec
43、e is bent into a convex shape ( ) which may also be considered as an outward bending test, face-out bending test or convex bending-test 3.1.7 inner bending test inward bending test face-in bending test concave bending test test, where the test piece is bent into a concave shape ( ) which may also be
44、 considered as an inward bending test, face-in bending test or concave bending-test 3.2 Symbols and designations The shape of the test piece and symbols are presented in Figure 1 and Table 1, respectively. The overall shape of the test piece is similar to the shape shown in 3.2 of IEC 62047-22:2014
45、for tensile tests. But the shape of the test piece can be rectangular or square. The test pieces has a flexible substrate and the conductive thin film deposited on the flexible substrate. IEC 62951-1:2017 IEC 2017 7 Figure 1 Shape of a test piece Table 1 Symbols and designations of a test piece Symb
46、ol Unit Designation l 1mm Gauge length for strain and resistance change measurements l 2mm Overall length h 1m Thickness of the conductive thin film h 2m Thickness of the flexible substrate b mm Width 4 Test piece 4.1 Design of test piece In order to minimize the influence of geometric size the test
47、 piece shall be reasonably similar to the final product. In particular, the size effect of the thin brittle films on failure is substantial due to the randomly distributed cracks or defects on the test piece. Therefore, the dimension of the test piece should be as much as possible of the same order
48、as that of the objective device component. The shape of a test piece is shown in Figure 1. For uniform strain distribution, the shape of the test piece is a rectangular or square strip. 4.2 Preparation of a test piece The test piece shall be prepared using the same fabrication process as the real de
49、vice fabricated for flexible electronics and flexible semiconductor devices, because the mechanical and electrical properties depend on the fabrication processes. Both the film thickness and substrate thickness should be uniform and small compared with the lateral dimensions. The flexible substrate and film have also the uniform material properties. Thin conductive film shall be carefully prepared to prevent formation of cracks or flaws and delamination from
