Foldable Substrates with Local Thickness for Bend and Puncture Resistance
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Solution Overview
Problem
Existing foldable displays and covers face challenges in achieving both small minimum bend radii and good impact and puncture resistance, with conventional glass-based substrates either having poor resistance or large bend radii.
Innovation Solution
The development of foldable substrates with a central portion having a reduced thickness and a plurality of protrusions, which enhance impact and puncture resistance while allowing for small bend radii, utilizing glass-based or ceramic-based materials with compressive stress regions and recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If glass-based substrates are made thinner to achieve small minimum bend radii, then foldability is improved, but impact and puncture resistance deteriorate
Solution Approach 1:
The substrate thickness is varied locally to create different functional zones: a first thickness in the first portion, a second thickness in the second portion, and a third thickness (less than both first and second) in the central portion. This local variation allows the substrate to bend easily in the central region while maintaining adequate thickness for strength in the portions that require structural support.
Solution Approach 2:
The substrate is divided into three distinct portions (first portion, second portion, and central portion) with different thickness characteristics. This segmentation allows each region to be optimized for its specific function: the thicker portions provide structural integrity and resistance to impact/puncture, while the thinner central portion enables small bend radii for foldability.
2Strength
If glass-based substrates are made thicker to improve impact and puncture resistance, then strength is improved, but minimum bend radius increases
Solution Approach 1:
The substrate thickness is varied locally to create different functional zones: a first thickness in the first portion, a second thickness in the second portion, and a third thickness (less than both first and second) in the central portion. This local variation allows the substrate to bend easily in the central region while maintaining adequate thickness for strength in the portions that require structural support.
Solution Approach 2:
The substrate is divided into three distinct portions (first portion, second portion, and central portion) with different thickness characteristics. This segmentation allows each region to be optimized for its specific function: the thicker portions provide structural integrity and resistance to impact/puncture, while the thinner central portion enables small bend radii for foldability.
3Ease of operation
If plastic displays are made with small minimum bend radii to improve foldability, then ease of operation is improved, but impact and puncture resistance deteriorate
Solution Approach 1:
The substrate thickness is varied locally to create different functional zones: a first thickness in the first portion, a second thickness in the second portion, and a third thickness (less than both first and second) in the central portion. This local variation allows the substrate to bend easily in the central region while maintaining adequate thickness for strength in the portions that require structural support.
Solution Approach 2:
The substrate is divided into three distinct portions (first portion, second portion, and central portion) with different thickness characteristics. This segmentation allows each region to be optimized for its specific function: the thicker portions provide structural integrity and resistance to impact/puncture, while the thinner central portion enables small bend radii for foldability.
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 substrates exhibit improved impact resistance and puncture resistance beyond expectations, maintaining low parallel plate distances and facilitating smooth folding, as demonstrated by Quasi-Static Puncture Test results.
Implementation Method 1
The foldable substrate 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 portions can comprise one or more compressive stress regions, which can further provide increased impact resistance and/or increased puncture resistance
Data Source
AI summary
Foldable substrates have a first portion, a second portion, and a central portion positioned therebetween. The first portion and the second portion have a substrate thickness less than a central thickness of the central portion. A plurality of protrusions extend from a first central surface area of the central portion. A total protrusion area is a sum of an area of an upper surface of each protrusion of the plurality of protrusions. A total central area is an area of the central portion. An area ratio of the total protrusion area to the total central area is from 0.10 to 0.70. Methods include disposing a patterned mask on an initial major surface of a foldable substrate and then etching the foldable substrate to form the plurality of protrusions.