Overview
IEC 61747-40-5:2018 specifies a mechanical performance test for display cover glass used in mobile devices, measuring the surface impact energy that causes fracture when the glass is subjected to a sharp contact. The method reproduces field-like failure from sharp-particle collisions by dropping a steel ball onto a sheet of coated abrasives placed on the glass, which is rigidly supported. The procedure records the energy at break and provides statistical output for material comparison and qualification.
Key topics and requirements
- Test principle: Simulate sharp-object impact by dropping a ball onto coated abrasives laid on the cover glass; failure is driven by sharp contact and enhanced by central tension in strengthened (ion-exchanged) glass.
- Apparatus elements: ball and release mechanism, height-adjustment beam, rigid base (granite), coated abrasives, armature and controller. The standard defines environmental conditioning and calibration expectations.
- Specimen characteristics: Typical specimens exceed 40 mm × 40 mm; thickness range commonly evaluated is 0.55 mm to 2.0 mm. Ball mass and drop heights are chosen to span the break energy range (example: a 4 g ball is often adequate for 0.55–1.0 mm glass; apparatus supports drops up to 50 cm).
- Procedure: Tests are statistical - each specimen receives sequential drops starting from a minimum height; drop height is increased by fixed increments until fracture occurs. Safety precautions for broken glass and moving components are required.
- Calculations and reporting: Determine breaking energy for each specimen and perform statistical analysis (Weibull analysis per IEC 61649 is referenced). The standard specifies required reporting fields and auxiliary information available upon request.
Applications and users
- Who uses it: cover-glass manufacturers, display OEMs, mobile device designers, materials engineers, third‑party test laboratories and quality/acceptance teams.
- Practical value:
- Reproduce a common field failure mode (sharp dynamic impact) for design validation.
- Compare mechanical resistance between glass formulations, thicknesses, and strengthening processes.
- Supplier qualification, incoming inspection protocols, and R&D for tougher cover glass.
- Support failure analysis and reliability documentation for product compliance and marketing claims.
Related standards
- IEC 61649 - Weibull analysis (statistical evaluation)
- IEC 61747-40-1 - Guidelines for mechanical testing of display cover glass
- ISO 6344-1 - Coated abrasives grain size
- ISO 8512-2 - Granite surface plates
- JIS R6111 - Artificial abrasives
Keywords: IEC 61747-40-5, display cover glass testing, mechanical testing, dynamic impact, sharp object, surface impact energy, coated abrasives, rigidly supported, Weibull analysis, mobile device glass.