Measurement procedures for materials used in photovoltaic modules - Part 6-3: Adhesion testing for PV module laminates using the single cantilevered beam (SCB) method

IEC TS 62788-6-3:2022 describes the single cantilevered beam (SCB) test, useful for characterizing adhesion in photovoltaic (PV) modules. This document offers a generalized method for performing the test, with the expectation that best practices for utilizing this test method will be developed for specific applications.
This document provides a method for measuring the adhesion energy of most interfaces within the photovoltaic (PV) module laminate. This method provides a measure of adhesive energy, via the critical energy release rate, and so is more useful for comparing adhesion of different specimen types; e.g. different materials, module or coupon samples, or materials before and after stress exposure.

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IEC TS 62788-6-3:2022 - Measurement procedures for materials used in photovoltaic modules - Part 6-3: Adhesion testing for PV module laminates using the single cantilevered beam (SCB) method
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IEC TS 62788-6-3 ®
Edition 1.0 2022-08
Measurement procedures for materials used in photovoltaic modules –
Part 6-3: Adhesion testing for PV module laminates using the single cantilevered
beam (SCB) method
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IEC TS 62788-6-3 ®
Edition 1.0 2022-08
Measurement procedures for materials used in photovoltaic modules –

Part 6-3: Adhesion testing for PV module laminates using the single

cantilevered beam (SCB) method

ICS 27.160 ISBN 978-2-8322-5561-2

– 2 – IEC TS 62788-6-3:2022 © IEC 2022
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Apparatus . 9
4.1 Load frame . 9
4.2 Loading tab . 10
5 Width-tapered cantilever beam . 10
5.1 General . 10
5.2 Beam design . 11
5.3 Beam selection . 11
6 Test method . 12
6.1 Specimen preparation . 12
6.2 Measurement procedure . 12
6.3 Analysis . 14
6.3.1 Critical adhesion energy, G . 14
7 Report . 15
Annex A (informative) Summary of background theory, and how this method can be
generalized . 16
A.1 Background theory . 16
A.2 Beam materials . 17
Annex B (informative) Guidance for specific use cases . 18
B.1 General . 18
B.2 Adhesion test coupons . 18
B.2.1 Backsheet / encapsulant adhesion . 18
B.2.2 Backsheet interlayer adhesion . 18
B.2.3 Glass/encapsulant adhesion . 19
B.2.4 Adhesion between different encapsulants . 19
B.2.5 Cell/encapsulant (coupons) . 20
B.3 Modules . 20
B.3.1 General . 20
B.3.2 Targeting a specific interface in a module . 20
Annex C (informative) Reference engineering diagrams for loading tab and beam . 23
Annex D (normative) Using a reference compliance curve to calculate G . 26
D.1 General . 26
D.2 Procedure . 26
D.2.1 Beam compliance measurement . 26
D.2.2 Definition of empirical parameters . 27
D.2.3 Validation of reference parameters . 27
D.2.4 Generating a custom set of α, β and γ parameters . 28
D.2.5 Calculation of crack length a for adhesion specimens . 29
Annex E (informative) Methods for measurement of final debond length a . 30
E.1 General . 30
E.2 Aluminum foil method. 30

E.3 Light method . 30
E.4 Pull-apart method . 30
Bibliography . 32

Figure 1 – Diagram of the loading connection using a clevis grip . 9
Figure 2 – Schematic of load frame with a) a platen for securing test coupon, and b)
modified to sit on top of a PV module . 10
Figure 3 – Photos of the loading tab alone, and attached to the beam . 10
Figure 4 – Width-tapered beam . 11
Figure 5 – Typical width-tapered cantilever beam load/displacement curve . 13
Figure 6 – Example of an a measurement on glass/encapsulant/cell specimens . 14
Figure B.1 – Top view of backsheet and encapsulant beam coupons . 21
Figure B.2 – Cross-sectional view of backsheet and encapsulant beam coupons . 22
Figure C.1 – Schematics of loading tab . 24
Figure C.2 – Schematics of beam . 25
Figure D.1 – Photo of a beam prior to start of the calibration measurement . 26
Figure D.2 – Photo of a beam at the end of the calibration measurement . 27
Figure D.3 – Plot used for generating beam calibration curves with the empirical fits
according to Formula (D.2) using values from Table D.1 . 29
Figure E.1 – Illustration of debond length measurement with a cohesive zone . 31

Table 1 – Typical adhesion strengths . 12
Table D.1 – Reference empirical fit parameters . 27
Table D.2 – Example read points for fit evaluation . 28

– 4 – IEC TS 62788-6-3:2022 © IEC 2022

Part 6-3: Adhesion testing for PV module laminates
using the single cantilevered beam (SCB) method

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