Laser Cleaving of Thick Brittle Substrates Using Breakdown Cavities
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Solution Overview
Problem
Existing methods for cutting thick glass substrates using pulsed lasers face limitations, including the need for mechanical force, microcracks, and defects, as well as inaccuracies in cutting thick glass due to filamentation methods, which are not applicable beyond 6 mm thickness and require complex high-precision systems.
Innovation Solution
A method involving a pulsed laser with a focused beam that moves progressively along the substrate at an angle and oscillates within the same plane, inducing a continuous stressed edge through optically induced breakdown cavities, allowing for precise cutting of substrates up to 30 mm thick without mechanical force and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If filamentation method is used to create tracks in glass substrate, then cutting capability is improved, but device complexity increases and manufacturing precision deteriorates due to multi-pass scanning requirements
Solution Approach 1:
The patent segments the laser processing into two distinct stages: first creating a stress line using low-power laser, then inducing breakdown cavities using high-power laser. This segmentation allows each stage to be optimized independently, avoiding the need for complex multi-pass scanning while achieving deep substrate penetration.
Solution Approach 2:
The stress line is created in advance before the breakdown cavity formation. This preliminary action prepares the substrate by introducing a stress concentration path, which guides the subsequent high-power laser breakdown process and ensures precise cutting without requiring complex real-time control systems.
2Productivity
If mechanical force is applied to cleave laser-treated material, then cutting is achieved, but manufacturing precision deteriorates due to chips and microcracks
Solution Approach 1:
The patent replaces mechanical cleaving force with a controlled optical field. The high-power laser induces breakdown cavities along the stress line, creating a self-propagating crack that separates the material without mechanical contact. This substitution eliminates chips and microcracks associated with mechanical force while maintaining high cutting speed.
Solution Approach 2:
The laser induces a phase transition in the material through optical breakdown, transforming the stressed region into a series of cavities that naturally propagate a clean fracture. This phase transition mechanism replaces mechanical separation with a controlled material transformation process.
3Manufacturing precision
If focused laser beam is used to create breakdown cavities, then manufacturing precision is improved, but device complexity increases due to focusing requirements for thick substrates
Solution Approach 1:
The patent employs dynamic focusing where the laser beam's focal point is continuously adjusted as it progresses through the substrate thickness. This dynamic adaptation allows precise cavity formation at varying depths without requiring complex static optical systems, maintaining manufacturing precision while simplifying the overall device architecture.
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 achieves high-quality straight, curved, or angled edges with reduced chipping and microcracking, enabling faster cutting and improved strength properties by maintaining a constant focal distance and continuous scanning across the substrate depth, regardless of beam direction.
Implementation Method 1
laser-induced breakdown of the material which in turn is caused by the laser beam focused in the body of the substrate
Data Source
AI summary
The invention relates to laser equipment, specifically pulsed scanning lasers used to cut brittle substrates. The authors propose a method and device for forming a stressed edge in the substrate for cleaving of the substrate, to which end a track of cavities is formed through optically induced breakdown in the body of tire material during its irradiation with a focused laser beam with a fixed focal distance during the course of angled scanning of the laser beam, with longitudinal movement along the length of the substrate. The technical result is: improved strength parameters of products and better quality of straight and oblique edges formed during substrate cleaving, absence of chips and microcracks, high rate of formation of the stressed cleaving edge, which implies faster laser cutting.