Laser Separation of Strengthened Glass Substrates
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Solution Overview
Problem
Existing methods for separating strengthened glass substrates, such as scribe-and-break techniques, often result in uncontrolled full-body separation and poor edge characteristics due to difficulties in applying precise mechanical force, especially with large sheets, leading to shattering and uncontrolled cracks.
Innovation Solution
A method involving a laser beam translated along a desired separation line on a strengthened glass substrate to create a scribe line and propagate a full-body crack without mechanical force, using a laser shield and cooling jet to control the crack propagation, allowing for self-separation into multiple glass articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If scribe-and-break techniques are used to separate strengthened glass substrates, then separation can be achieved, but uncontrolled full-body separation and poor edge characteristics occur
Solution Approach 1:
The patent replaces the mechanical scribe-and-break system with a laser-based system. The laser beam creates a controlled modification layer in the glass substrate that guides crack propagation, eliminating the need for mechanical force application. This substitution of mechanical action with optical energy enables precise separation while maintaining edge quality, directly resolving the contradiction between separation precision and edge quality.
Solution Approach 2:
The patent changes the physical state and properties of the glass substrate by using laser heating to create a modified layer with specific thermal and mechanical properties. By controlling laser parameters (power, speed, focus) and cooling conditions, the process creates a controlled stress field that guides crack propagation along the desired line, achieving both precise separation and good edge characteristics.
2Manufacturing precision
If mechanical force is applied to break large strengthened glass substrate sheets, then separation can be achieved, but shattering and uncontrolled cracks occur
Solution Approach 1:
The patent eliminates mechanical force application entirely by using laser-induced thermal fields to create controlled fracture. The laser modifies the glass structure and creates a stress field that directs crack propagation, replacing the unpredictable mechanical breaking process with a controlled optical-thermal-mechanical process that maintains substrate integrity while achieving precise separation.
Solution Approach 2:
The patent introduces a laser-modified layer as an intermediary between the laser beam and the final fracture. This modified layer acts as a guide for crack propagation, ensuring that the fracture follows the desired path without uncontrolled branching or shattering. The intermediary layer transfers the laser energy into controlled mechanical stress, resolving the contradiction between separation control and substrate integrity.
3Manufacturing precision
If laser beam is used to create scribe line in strengthened glass, then precise separation line can be formed, but controlled full-body crack propagation is difficult to achieve
Solution Approach 1:
The patent performs preliminary action by first creating a laser-modified layer in the glass substrate before inducing the full-body crack. This modified layer, created by controlled laser heating and cooling, serves as a pre-prepared pathway that guides subsequent crack propagation. The preliminary modification ensures that when the crack initiates, it follows the desired scribe line precisely, resolving the contradiction between scribe line precision and crack propagation control.
Solution Approach 2:
The patent utilizes phase transitions in the glass material through laser-induced thermal cycling. The laser heating creates a modified layer with changed thermal and mechanical properties, and the subsequent cooling creates thermal stress. These phase transitions in the material's physical state create a controlled environment for crack propagation, ensuring that the crack follows the modified layer precisely while maintaining reliability.
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
Enables controlled separation of strengthened glass substrates into multiple pieces without mechanical force, improving edge characteristics and reducing the risk of shattering, thereby enhancing the reliability and precision of the separation process.
Implementation Method 1
translating a laser beam on a surface of the strengthened glass substrate along a line of desired separation
Implementation Method 2
translating a laser beam on a surface of the strengthened glass substrate from a first edge toward a second edge, thereby producing a residual stress field within the strengthened glass substrate along the line of desired separation
Implementation Method 3
backward-propagating a controlled full-body crack within the strengthened glass substrate from the second edge toward the first edge substantially along the line of desired separation
Data Source
AI summary
Methods of separating a strengthened glass substrate having a compressive surface layer and an inner tension layer include translating a laser beam on a surface of the strengthened glass substrate along a line of desired separation from a first edge of the strengthened glass substrate toward a second edge of the strengthened glass substrate. Methods further include backward-propagating a controlled full-body crack within the strengthened glass substrate from the second edge toward the first edge substantially along the line of desired separation. A scribe line may be formed on a surface of the strengthened glass substrate such that the strengthened glass substrate self-separates along the scribe line. A residual stress field may be created within the strengthened glass substrate such that a full-body crack backward-propagates from an exit defect located at the second edge toward the first edge along a line of desired separation, thereby separating the strengthened glass substrate.