Display Glass Laser Cutting with Defect Lines for Clean Edges
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Solution Overview
Problem
Current methods for cutting and separating glass substrates, particularly for Thin Film Transistor (TFT) devices, are inefficient in terms of speed, cleanliness, cost, and reliability, with existing laser cutting technologies often resulting in high surface roughness and debris.
Innovation Solution
A laser cutting process using an ultra-short pulse laser to create defect lines within the glass substrate, followed by thermal stress induction with a CO2 laser, allowing for precise cutting of complex shapes and high-speed separation with minimal debris and surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional laser cutting is used on glass substrates, then cutting speed can be increased, but surface roughness and debris increase
Solution Approach 1:
The patent employs periodic pulsed laser action instead of continuous laser beam. The laser delivers short pulses at specific intervals, creating periodic defect lines that guide crack propagation. This periodic action allows the glass to fracture cleanly along predetermined paths without excessive melting or roughening, thus maintaining surface quality at high cutting speeds.
Solution Approach 2:
The laser process creates preliminary defect lines within the glass substrate before actual separation occurs. These defect lines serve as pre-formed pathways that guide subsequent crack propagation during mechanical separation. By preparing these defect lines in advance through controlled laser irradiation, the glass separates cleanly along the desired contour without requiring forceful mechanical breaking that would damage the surface.
2Productivity
If conventional cutting methods are used, then process simplicity is maintained, but productivity is low
Solution Approach 1:
The patent replaces traditional mechanical cutting methods with a laser-based system that creates defect lines through optical energy. Instead of using physical blades or saws that require complex mechanical mechanisms for precise cutting, the system uses laser beams to induce subsurface defects that guide fracture. This substitution dramatically increases productivity while the added optical system complexity is offset by the elimination of mechanical cutting apparatus.
3Productivity
If high power laser is used to increase cutting speed, then productivity improves, but edge quality and strength deteriorate
Solution Approach 1:
The use of periodic pulsed laser delivery allows high peak powers to be achieved without continuous heating. The pulsed nature provides intervals for heat dissipation, preventing excessive thermal accumulation that would compromise edge strength. The periodic defect line creation maintains high cutting speeds while preserving edge integrity through controlled thermal cycles.
Solution Approach 2:
The laser energy is concentrated locally to create defect lines only at the intended cut path, rather than heating the entire glass surface. This localized energy deposition ensures that only the necessary regions undergo modification, preserving the structural integrity and strength of adjacent edge areas while enabling fast cutting along the defect line paths.
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 fast, clean, and reliable cutting of glass substrates with improved edge strength and surface quality, capable of cutting at speeds over 1 m/sec and producing edges with Ra surface roughness of less than 0.5 microns.
Implementation Method 1
the laser beam focal line generating an induced absorption within the material, and the induced absorption producing defect lines or a damage track along the laser beam focal line within the workpiece
Implementation Method 2
focusing a pulsed laser beam into a laser beam focal line oriented along the beam propagation direction. The laser beam focal line is also directed into the glass composite workpiece, the laser beam focal line generating an induced absorption within the material
Implementation Method 3
The method involves the utilization of an ultra-short pulse laser and can be followed by a CO2 laser to create thermal stress, sometimes coupled with high pressure air flow, for fully automated separation
Data Source
AI summary
The present invention relates to a laser cutting technology for cutting and separating thin substrates of transparent materials, for example to cutting of display glass compositions mainly used for production of Thin Film Transistors (TFT) devices. The described laser process can be used to make straight cuts, for example at a speed of >0.25 m/sec, to cut sharp radii outer corners (<1 mm), and to create arbitrary curved shapes including forming interior holes and slots. A method of laser processing an alkaline earth boro-aluminosilicate glass composite workpiece includes focusing a pulsed laser beam into a focal line. The pulsed laser produces pulse bursts with 5-20 pulses per pulse burst and pulse burst energy of 300-600 micro Joules per burst. The focal line is directed into the glass composite workpiece, generating induced absorption within the material. The workpiece and the laser beam are translated relative to each other to form a plurality of defect lines along a contour, with adjacent defect lines have a spacing of 5-15 microns.