Substrate Cutting with Laser-Ablated Recesses for Curved Crack Control
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Solution Overview
Problem
Current methods for cutting substrates, particularly thin and flexible ones, are limited in processing speed and accuracy, especially when attempting to create curved cuts, and often result in stray breaking or require additional post-processing steps to address chipping and edge quality issues.
Innovation Solution
The method involves using laser ablation to form non-uniformly distributed stress-concentrating recesses on the substrate, which are then subjected to stress to initiate crack propagation along a desired cutting line, allowing for efficient and flexible cutting of complex geometries, including curved shapes, by optimizing the separation and orientation of recesses and applying stress through thermal or mechanical means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical scribing is used to cut glass substrates, then cutting cost is reduced and simple straight cuts are achievable, but processing speed is limited and curved shapes cannot be cut
Solution Approach 1:
The patent replaces the mechanical scribing system with a laser-based system. The laser forms recesses through optical energy absorption and thermal stress, eliminating the need for physical contact between the cutting tool and glass surface. This substitution enables curved and complex shape cutting while maintaining cost-effectiveness and processing speed.
Solution Approach 2:
The patent changes the fundamental cutting parameter from mechanical force to laser-induced thermal stress. By controlling laser parameters (power, pulse duration, scanning speed) and thermal stress conditions, the system achieves versatile cutting capabilities for various shapes including curves, while maintaining efficiency and low cost.
2Manufacturing precision
If mechanical cutting wheels with stress raisers are used, then controlled fracture is achieved, but stray breaking occurs due to glass fragility
Solution Approach 1:
The patent applies local quality by creating localized recesses at specific positions along the cutting path rather than continuous mechanical contact. Each recess is precisely formed by laser ablation at controlled intervals, concentrating stress only where needed to initiate and guide crack propagation while leaving other areas undisturbed, thus preventing stray breaking.
Solution Approach 2:
The patent performs preliminary action by pre-forming recesses that concentrate stress before applying the final breaking force. These pre-formed stress concentration points guide the crack propagation path precisely along the desired cutting line, ensuring controlled fracture without unpredictable stray breaking.
3Productivity
If laser induced controlled fracture is used for thick glass, then cutting speed reaches 0.3m/s and curves can be cut, but equipment cost increases significantly
Solution Approach 1:
The patent applies partial action by forming recesses at optimized intervals rather than continuous laser processing. The recess spacing is carefully calculated to provide sufficient stress concentration for crack initiation while minimizing the total laser processing time and energy consumption, achieving high speed cutting without excessive equipment complexity.
Solution Approach 2:
The patent segments the cutting process into discrete recess formation steps rather than continuous processing. By creating multiple separated recesses along the cutting path and then applying a single breaking force, the system achieves high-speed cutting of complex shapes while using simpler, more cost-effective equipment compared to continuous laser fracture systems.
4Manufacturing precision
If recesses are formed uniformly along the cutting line, then crack propagation is initiated, but crack deviation occurs and cut precision decreases
Solution Approach 1:
The patent applies asymmetry by using non-uniform recess spacing and varying recess geometries (depth, width, shape) along the cutting path. This asymmetric configuration compensates for variations in glass properties, stress distribution, and curvature radius at different positions, ensuring consistent crack propagation control and high cut precision throughout the entire cutting line.
Solution Approach 2:
The patent dynamically changes recess parameters (spacing, depth, width, shape) along the cutting path based on local requirements. For curved sections, recess spacing and orientation are adjusted to follow the curvature; for varying glass thickness or properties, recess depth and shape are modified to maintain effective stress concentration and crack guidance, ensuring reliable propagation control.
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 approach enables rapid and precise cutting of thin, flexible substrates with improved edge quality and reduced risk of stray fractures, facilitating the processing of complex shapes without the need for additional post-processing steps.
Implementation Method 1
A glass substrate containing an edge micro-crack is locally heated by a CO2 laser to a temperature just below the glass softening temperature causing compressive stresses in the substrate
Implementation Method 2
A coolant jet is subsequently applied to the heated region. Rapid cooling causes the stress to become tensile and induce mode 1 fracture in the glass along the line heated by the laser
Implementation Method 3
forming a plurality of recesses in a surface of the substrate using laser ablation
Data Source
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AI summary
Methods and apparatus for cutting a substrate are disclosed. In one arrangement, a plurality of recesses are formed in the surface of the substrate. The recesses as such that a stress can be applied to the substrate that is concentrated by the recesses. The concentrated stress causes the substrate to be cut along a cutting line that passes through the recesses. The cutting occurs via propagation of a crack through the recesses.