Laser Burst Profiles for Clean Separation of Transparent Workpieces
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Solution Overview
Problem
Current methods for cutting and separating glass substrates are inefficient, lacking speed, cleanliness, cost-effectiveness, repeatability, and reliability.
Innovation Solution
A method of laser processing using a pulsed laser beam with pulse bursts containing multiple sub-pulses, tailored to form a pulsed laser beam focal line that induces absorption and creates defects in the glass substrate, allowing for controlled separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser processing methods are used on glass substrates, then the process can be implemented with standard equipment, but the separation speed is slow and the process lacks efficiency
Solution Approach 1:
The patent employs periodic pulsed laser bursts with multiple sub-pulses separated by specific time intervals (e.g., 10-100 ns between sub-pulses, 1-100 μs between bursts) to create cumulative thermal effects and stress in the glass substrate. This periodic action enables faster material modification and separation compared to continuous or single-pulse methods, directly improving productivity while reducing processing time.
Solution Approach 2:
The patent systematically varies laser processing parameters including pulse duration (1 ns to 100 μs), burst repetition rates (1 kHz to 1 MHz), peak power levels, and pulse spacing to optimize the interaction with glass substrates. By changing these parameters, the process achieves higher separation speeds and reduced processing times while maintaining quality, resolving the contradiction between productivity and time loss.
2Productivity
If high energy laser pulses are used to increase separation speed, then productivity improves, but damage to the glass substrate and edge strength deteriorate
Solution Approach 1:
The patent divides the laser energy delivery into multiple sub-pulses within each burst (e.g., 2-10 sub-pulses per burst) with controlled energy distribution. This segmentation allows cumulative material modification without concentrating excessive energy in a single pulse, thereby achieving fast separation while minimizing substrate damage and preserving edge strength.
Solution Approach 2:
The periodic burst structure with controlled repetition rates and intra-burst pulse spacing enables gradual thermal accumulation and stress buildup in the glass. This periodic action achieves the desired separation speed while distributing energy input over time, preventing localized overheating and damage that would occur with single high-energy pulses.
3Reliability
If multiple laser pulses are applied to create defects for separation, then separation reliability improves, but the complexity of the processing method increases
Solution Approach 1:
The patent implements a periodic burst mode where groups of sub-pulses are delivered at controlled intervals, creating consistent defect patterns in the glass substrate. This periodic structure improves separation reliability by ensuring uniform defect distribution while maintaining relatively simple processing control compared to fully adaptive or continuously variable methods.
Solution Approach 2:
The patent optimizes specific parameter ranges (pulse duration 1 ns to 100 μs, burst repetition 1 kHz to 1 MHz, sub-pulse spacing 10-100 ns) to achieve reliable separation within well-defined operating windows. By establishing these optimized parameter ranges, the method achieves high reliability without requiring complex real-time adjustment mechanisms, thus limiting the increase in processing complexity.
4Strength
If short pulse durations are used to minimize heat affected zone, then edge strength improves, but the ability to induce sufficient absorption and create defects deteriorates
Solution Approach 1:
The patent segments the total energy delivery into multiple sub-pulses within each burst, where each sub-pulse has short duration (1 ns to 100 μs) to minimize heat-affected zones and preserve edge strength. The cumulative effect of multiple sub-pulses creates sufficient absorption and defect formation, resolving the contradiction between maintaining edge strength and achieving adequate defect quality.
Solution Approach 2:
The patent uses continuous bursts of multiple sub-pulses delivered in rapid succession to maintain continuous useful action on the glass substrate. This continuous multi-pulse approach ensures sufficient energy accumulation for defect formation while each individual sub-pulse remains short enough to minimize heat diffusion, thereby maintaining both edge strength and defect formation quality.
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
The method achieves faster, cleaner, and more reliable separation of glass substrates with reduced break resistance, minimizing damage and ensuring high edge strength of the separated surfaces.
Implementation Method 1
the pulsed laser beam focal line induces absorption in the transparent workpiece, the induced absorption producing a defect in the transparent workpiece
Data Source
AI summary
A method of laser processing a transparent workpiece includes directing a pulsed laser beam into the transparent workpiece. The pulsed laser beam includes pulse bursts having 2 sub-pulses per pulse burst or more, each pulse burst of the pulsed laser beam has a burst duration Tbd of 380 ns or greater; and the pulsed laser beam forms a pulsed laser beam focal line in the transparent workpiece, the pulsed laser beam focal line inducing absorption in the transparent workpiece, the induced absorption producing a defect in the transparent workpiece. The pulsed laser beam focal line includes a wavelength λ, a spot size wo, and a Rayleigh range ZR that is greater thanFDπwo2λ,where FD is a dimensionless divergence factor comprising a value of 10 or greater.