Foldable Substrates with Recessed Central Portions
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Solution Overview
Problem
Existing foldable displays and protective covers face challenges in achieving both small minimum bend radii and good impact and puncture resistance, with plastic displays lacking in resistance and ultra-thin glass-based sheets being prone to damage.
Innovation Solution
The development of foldable substrates with a glass-based or ceramic-based composition, featuring a central portion with a reduced thickness and recessed surfaces, along with transition regions that smoothly decrease in thickness, to enhance impact and puncture resistance while allowing for small bend radii.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If plastic displays 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 employs composite material structures combining glass-based or ceramic-based portions with polymer portions. The glass/ceramic layers provide high impact and puncture resistance, while the polymer portions provide flexibility and enable small bend radii. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent implements varying thickness profiles where the substrate is thinnest at the neutral axis (enabling small bend radii) and thicker at the surfaces (providing impact and puncture resistance). The transition regions smoothly connect these areas, allowing each location to optimize for its specific functional requirement.
2Shape
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 creates a non-uniform thickness profile where the glass-based substrate is thinnest at the neutral axis (enabling small bend radii of about 10 mm or less) while maintaining greater thickness at the surfaces (providing impact and puncture resistance). This local variation in thickness allows each region to optimize for its specific functional requirement.
Solution Approach 2:
The patent combines glass-based or ceramic-based materials with polymer materials in a composite structure. The glass/ceramic portions provide high strength and resistance to impact and puncture, while the polymer portions provide flexibility and enable the ultra-thin profile needed for small bend radii.
3Strength
If thicker glass-based sheets are used to improve impact and puncture resistance, then resistance is improved, but minimum bend radius increases
Solution Approach 1:
The patent implements a thickness profile where the substrate is thinnest at the neutral axis (enabling small bend radii) and thicker at the surfaces (providing impact and puncture resistance). This local variation allows the substrate to achieve both small bend radii and high resistance without requiring uniform thickness throughout.
4Strength
If glass-based substrates are used to improve impact and puncture resistance, then resistance is improved, but dimensional stability and mechanical instability deteriorate
Solution Approach 1:
The patent combines glass-based or ceramic-based materials with polymer materials in a composite structure. The glass/ceramic portions provide high strength and resistance to impact and puncture, while the polymer portions provide flexibility and dimensional stability, preventing mechanical instabilities during folding.
Data Source
AI summary
Foldable substrates comprise a first portion, a second portion, and a central portion positioned therebetween. The central portion comprises a first transition region comprising a first transition width and a first transition surface area extending between a first surface area of the first portion and a first central surface area of the central portion with a first average angle. In aspects, the first average angle is from about 167° to about 179°. In aspects, the first transition width is from about 150 micrometers to about 700 micrometers. Methods comprise disposing an etch mask over the first major surface of the foldable substrate before etching the foldable substrate. In aspects, the etch mask comprises a first polymer layer positioned between a first barrier layer and the first major surface. In aspects, the etch mask comprises a positive photoresist.