IEC 62899-202-7:2021

Overview

IEC 62899-202-7:2021 defines a quantitative test method for measuring the peel strength of a printed layer on a flexible substrate using the 90° peel method. Unlike conventional peel tests that require electroplating to thicken the printed layer for gripping, this standard peels the flexible substrate itself - a useful approach for porous or thin printed films (conductive inks) where electroplating can contaminate the interface. The procedure enables reliable comparison of adhesion for layers printed on the same substrate under defined thickness and environmental conditions.

Key topics and technical requirements

• Scope: Measures adhesion between a printed conductive layer and flexible substrate when that interface is the weakest in the test stack.
• Test geometry: 90° peel configuration with the substrate bent to 90° while the panel moves horizontally and the peeled portion is pulled vertically.
• Sample dimensions (examples):
  • Test panel ~50 mm × 120 mm
  • Printed layer width: 10 mm ± 0.2 mm; length: 100 mm
  • Substrate thickness range giving stable data: 25 µm to 125 µm
• Standard atmospheric conditions: temperature (23 ± 2) °C and relative humidity (50 ± 5) %.
• Apparatus: 90° peel tester with linear test length ≥ 50 mm; load cell range typically 20 N–100 N; displacement and load sensors to record peeling curves.
• Data analysis: Peel strength is calculated as the average peel load divided by sample width, using steady-state load values after initial transient. Results and measurement parameters must be reported per the standard.
• Applicability constraint: This method is usable only if F(sub-layer) < F(layer), F(layer-ad), F(ad-panel), F(sub) - i.e., the substrate/printed-layer interface fails before other interfaces or cohesive failure.

Practical applications

• Evaluating adhesion of conductive inks and printed metal layers on flexible polymers (PI, PET, PEN, etc.).
• Comparing adhesion across formulations, curing conditions, print thicknesses or substrate treatments without electroplating.
• Supporting reliability qualification for flexible printed interconnects, electrodes, RFID tags, wearable electronics and flexible sensors.
• Providing standardized adhesion data for R&D, production quality control, and supplier specification.

Who should use this standard

• Materials scientists and R&D teams developing conductive inks and printable films
• Quality and test engineers in flexible electronics, PCB and printed circuit manufacturing
• Third‑party test laboratories performing adhesion characterization
• Product designers and OEMs specifying adhesion performance for flexible devices

Related standards

• IEC 62899-202:2016 - Printed electronics - Part 202: Materials - Conductive ink (normative reference)
• Other parts of the IEC 62899 series covering printed electronics materials and test methods

Keywords: IEC 62899-202-7:2021, printed electronics, peel strength, 90° peel method, flexible substrate, conductive ink, adhesion testing, printed layer.