Chemically Strengthened Foldable Glass for Bend and Impact Resistance
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Solution Overview
Problem
Conventional foldable displays and covers face challenges in achieving small minimum bend radii while maintaining good impact and puncture resistance, with plastic displays being inadequate and ultra-thin glass-based sheets having poor resistance, and thicker glass-based sheets having large minimum bend radii.
Innovation Solution
The development of foldable substrates comprising glass-based and/or ceramic-based portions with compressive stress regions, direct bonding, and controlled thicknesses to enhance impact and puncture resistance, along with methods that include chemical strengthening and controlled expansion to mitigate mechanical instabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ultra-thin glass-based sheets are used to achieve small minimum bend radii, then the bend radius is reduced, but impact and puncture resistance deteriorate
Solution Approach 1:
The patent applies chemical strengthening by immersing the glass-based substrate in a molten salt bath containing potassium salts, which exchanges sodium ions in the glass surface with larger potassium ions. This creates compressive stress in the surface layer, significantly enhancing impact and puncture resistance while maintaining the thin profile and small bend radius required for foldable applications
Solution Approach 2:
The patent creates a composite structure through chemical strengthening where the glass substrate develops a compressed surface layer and a tensile core layer. This composite-like internal structure allows the thin glass sheet to achieve both small bend radius and high impact/puncture resistance simultaneously
2Strength
If thicker glass-based sheets are used to improve impact and puncture resistance, then strength is improved, but minimum bend radius increases
Solution Approach 1:
The patent uses chemical strengthening to alter the mechanical properties of thin glass sheets, creating surface compressive stress that compensates for the reduced thickness. This allows achieving high impact and puncture resistance equivalent to or exceeding thicker sheets while maintaining small bend radius
3Shape
If plastic displays are used to achieve small minimum bend radii, then flexibility is improved, but impact and puncture resistance deteriorates
Solution Approach 1:
The patent applies chemical strengthening to glass-based substrates to enhance their toughness and resistance to impact and puncture, making them suitable for foldable applications where plastic materials fail despite offering better flexibility and small bend radius
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 solution provides foldable substrates with improved impact and puncture resistance, reduced mechanical instabilities, and minimal optical distortions, enabling small bend radii and efficient production processes.
Implementation Method 1
The portions can comprise glass-based and/or ceramic-based portions, which can provide good dimensional stability, reduced incidence of mechanical instabilities, good impact resistance, and/or good puncture resistance
Implementation Method 2
the first portion and/or the second portion can comprise glass-based portions and/or ceramic-based portions comprising one or more compressive stress regions, which can further provide increased impact resistance and/or increased puncture resistance
Implementation Method 3
the first portion and/or the second portion can comprise glass-based portions and/or ceramic-based portions comprising one or more compressive stress regions
Data Source
AI summary
Foldable apparatus comprise a foldable substrate comprising a substrate layer comprising a first major surface contacting a first inner surface area of a first portion. The first major surface of the substrate layer contacts a second inner surface area of a second portion. The first portion and the second portion are separated by a minimum distance. In aspects, the first portion and/or the second portion is directly bonded to the first major surface. In aspects, the substrate layer is chemically strengthened. In aspects, the first portion and/or the second portion are unstrengthened. Methods comprise contacting at least the first major surface of the substrate layer with a hydroxide-containing solution. Methods comprise forming a foldable substrate by disposing the first portion over the first major surface, disposing the second portion over the first major surface, and then heating the foldable substrate.