Glass Product Stress Profile Control for Impact Resistance
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Solution Overview
Problem
Glass products used in portable electronic devices face challenges in maintaining thinness while enduring external impacts, as existing strengthening methods lack precise control over stress profiles to enhance strength effectively.
Innovation Solution
A glass product design featuring compressive and tensile regions with specific stress profiles, including compressive regions extending from the surface to a predetermined depth with varying stress levels and slopes, and a tensile region in between, optimized through ion exchange processes to enhance strength and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If glass products are made thinner for portability, then device weight and size are reduced, but resistance to external impact deteriorates
Solution Approach 1:
The patent applies local quality by creating non-uniform stress distribution within the glass product. Specifically, it forms a compressive stress layer at the surface (extending to 10-50 μm depth) and a tensile stress layer in the interior region. This localized stress arrangement allows the thin glass to resist external impacts effectively at the surface while maintaining overall thinness for portability.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the stress profile parameters including the depth of the compressive layer (10-50 μm), the magnitude of compressive stress (300-900 MPa at surface), and the transition to tensile stress in the interior. These parameter optimizations enable the glass to achieve enhanced impact resistance while maintaining thin dimensions suitable for portable devices.
2Strength
If thermal or chemical strengthening is applied to improve glass strength, then impact resistance is enhanced, but precise control of stress profile becomes difficult
Solution Approach 1:
The patent applies segmentation by dividing the stress profile into distinct regions: a surface compressive stress layer (10-50 μm depth), an intermediate transition zone, and an interior tensile stress layer. This segmented stress distribution is achieved through controlled ion exchange processes, allowing precise manipulation of stress characteristics in each region independently, thereby achieving accurate stress profile control that enhances glass strength.
3Strength
If compressive stress is increased at the surface to prevent crack initiation, then crack resistance is improved, but stress concentration may lead to sudden failure
Solution Approach 1:
The patent applies preliminary anti-action by pre-establishing a compressive stress layer at the glass surface before external impacts or cracks occur. This compressive layer (extending 10-50 μm from surface with 300-900 MPa stress) acts in opposition to tensile stresses that would normally cause crack initiation and propagation. By having this counteracting compressive stress already in place, the glass gains enhanced crack resistance while the gradual transition to interior tensile stress prevents sudden catastrophic failure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The glass product achieves improved strength and crack resistance by precisely controlling stress profiles, effectively preventing breakage and crack propagation from external impacts, while maintaining thinness.
Implementation Method 1
optimized through ion exchange processes to enhance strength and crack resistance
Data Source
AI summary
A glass product includes: a first compressive region at a first surface; a second compressive region at a second surface; and a tensile region between the first and second compression regions. A stress profile of the first compressive region includes a first trend line between the first surface and a first transition point, a second trend line between the first transition point and a second transition point, and a third trend line between the second transition point and a point at a first compression depth from the first surface. A depth from the first surface to the first transition point is 10 μm or less, a stress at the first transition point is 200 MPa or greater, a depth from the first surface to the second transition point is 50 μm to 80 μm, and a stress at the second transition point is 40 MPa to 100 MPa.