Overview
IEC 61747-40-3:2015 defines a mechanical performance test for display cover glass used in mobile electronic devices, measuring surface impact resistance by a ball drop method that induces biaxial flexure. The procedure is statistical: a series of specimens from a sample are impacted by a dropping ball and the biaxial flexural energy to failure (breaking energy) is recorded and analyzed to characterize strength and reliability.
Key topics
- Scope and intent
- Mechanical testing of cover glass for electronic flat panel displays in mobile devices.
- Focus on measuring energy required to cause fracture under a centrally applied ball drop (biaxial flexure).
- Apparatus components
- Height adjustment beam (marked in 5 cm increments; max drop ≥ 180 cm).
- Specimen holder (rigid polymer frame with a 4–6 mm ledge and containment barrier).
- Armature, ball release mechanism, ball release controller, and base.
- Test ball - example: 128 g ball is cited as adequate for 50 mm × 50 mm specimens (0.55–2.0 mm thick).
- Procedure fundamentals
- Sample vs specimen: statistical sample of specimens sharing common pedigree.
- Start at a minimum drop height and increase in fixed increments until breakage.
- Pre-conditioning and environment per IEC 61747-40-1; specimens stored in test environment for at least four hours.
- Safety considerations: broken glass hazards and compression risk from moving ball.
- Measurements and analysis
- Breaking energy calculated from ball mass and drop height (with allowed height correction for specimen thickness).
- Statistical treatment of results (including Weibull analysis per IEC 61649) to report characteristic strengths and reliability metrics.
- Reporting requirements include per-test data and sample statistics.
Applications
- Who uses it
- Display manufacturers, cover-glass suppliers, mobile device OEMs, independent test labs, R&D and quality assurance teams.
- Practical uses
- Compare surface impact resistance across glass formulations, strengthening processes (e.g., ion exchange), or manufacturing lots.
- Validate cover-glass performance targets for drop-impact durability specifications.
- Provide data for material selection, design trade-offs (thickness vs weight vs strength), and reliability claims.
Related Standards (if applicable)
- IEC 61747-40-1 - Guidelines for mechanical testing of display cover glass (environment and general test guidance).
- IEC 61649:2008 - Weibull analysis (statistical analysis of failure data referenced for reporting).
Keywords: IEC 61747-40-3, ball drop, biaxial flexural energy to failure, cover glass testing, mobile display impact resistance, specimen holder, Weibull analysis.
Open preview (PDF)Liquid crystal display devices - Part 40-3: Mechanical testing of display cover glass for mobile devices - Biaxial flexural energy to failure (ball drop)
