Cover Glass Edge Smoothing via Chemical Etching
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Solution Overview
Problem
Conventional cover glass for mobile terminal devices, particularly those with complex shapes, face challenges in achieving high mechanical strength due to surface roughness and micro-cracks from mechanical processing, which limits their practical application and increases processing costs.
Innovation Solution
The cover glass is manufactured by cutting a plate-shaped glass substrate into a desired shape using etching, with a molten glass surface and compressive stress layers, eliminating the need for mechanical processing and resulting in a smooth edge face with surface roughness of 10 nm or less, and is chemically strengthened by ion exchange for enhanced mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If mechanical processing (chamfering) is used to shape the cover glass edge face, then the desired shape can be obtained, but surface roughness becomes coarse and micro-cracks are generated, reducing mechanical strength
Solution Approach 1:
The patent replaces mechanical processing (chamfering) with chemical etching to shape the edge face. The glass substrate is etched using HF-based etchant to form the desired edge shape, which eliminates the generation of micro-cracks and coarse surface roughness associated with mechanical methods, thereby maintaining high mechanical strength while achieving the required geometry.
Solution Approach 2:
The patent changes the processing method from mechanical to chemical, and applies ion exchange treatment to modify the surface properties. The chemical etching parameters (etchant concentration, etching time, temperature) are controlled to achieve smooth surfaces with surface roughness of 10 nm or less, while ion exchange creates compressive stress layers that enhance mechanical strength.
2Length of moving object
If the cover glass is made thinner to reduce device thickness, then the device can be slimmed down, but the mechanical strength and shock resistance of the cover glass are reduced
Solution Approach 1:
The patent uses ion exchange treatment to create compressive stress layers in the cover glass surface. This chemical strengthening process allows thin glass substrates to achieve high mechanical strength and shock resistance by forming a hardened surface layer, enabling device thinning without compromising cover glass durability.
3Shape
If complex shapes (negative curvature, holes) are formed on the cover glass to match display screen shapes, then the aesthetic and functional requirements are met, but mechanical strength is reduced and processing cost increases
Solution Approach 1:
The patent uses chemical etching instead of mechanical processing to create complex shapes including negative curvature and holes. The HF-based etchant can precisely remove glass material to form intricate geometries without generating micro-cracks or surface roughness, maintaining mechanical strength while achieving the required complex shapes that match display screen configurations.
4Reliability
If the distance between the protective plate and display is increased to absorb bending, then the protective function is improved, but the device thickness increases
Solution Approach 1:
The patent applies ion exchange treatment to create compressive stress layers that significantly enhance the bending resistance and mechanical strength of the cover glass. This chemical strengthening allows the cover glass to maintain high protective function even at minimal distances from the display, enabling device thinning while preserving the protective function.
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
This method enables the production of cover glass with high mechanical strength and smooth surfaces, suitable for complex shapes, reducing processing costs and preventing micro-cracks, thus enhancing the durability and functionality of mobile terminal devices.
Implementation Method 1
A glass substrate is chemically etched with HF for removing unnecessary portions.
Implementation Method 2
forming a compressive stress layer in the surface by chemical strengthening
Data Source
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AI summary
To provide cover glass for mobile terminals exhibiting high strength in a thin plate thickness state to enable reductions in thickness of apparatuses when inserted in the apparatuses, cover glass (1) for a mobile terminal of the invention is cover glass (1) that is obtained by forming a resist pattern on main surfaces of a plate-shaped glass substrate, then etching the glass substrate with an etchant using the resist pattern as a mask, and thereby cutting the glass substrate into a desired shape and that protects a display screen of the mobile terminal, where an edge face of the cover glass (1) is formed of a molten glass surface, and as surface roughness of the edge face, arithmetic mean roughness Ra is 10 nm or less.