Glass Perforation Layout for Precise Low-Damage Laser Separation
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Solution Overview
Problem
Conventional laser cutting techniques face limitations in cutting thin glass and glass-ceramics due to heat-affected zones, thermal stress, uncontrolled material removal, and sub-surface damage, making it difficult to achieve precise and controlled separation of glass sheets.
Innovation Solution
Utilizing an ultrashort pulse laser beam to create micron-sized defects or perforations in transparent materials, followed by a CO2 laser for thermal stress to facilitate controlled separation, with a reflective or absorptive layer to prevent damage to underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional laser cutting techniques are used to cut glass, then cutting capability is achieved, but heat-affected zones and sub-surface damage occur extending hundreds of microns below the surface
Solution Approach 1:
The patent changes the laser pulse duration parameter from conventional nanosecond or longer pulses to ultrashort picosecond pulses. This parameter change fundamentally alters the interaction mechanism between laser and glass, enabling ablation without significant heat diffusion to surrounding areas, thus eliminating heat-affected zones and sub-surface damage while maintaining cutting capability
Solution Approach 2:
The patent utilizes the phase transition of glass from solid to vapor/plasma state through ultrashort laser pulse ablation. The picosecond pulses deliver energy so rapidly that material is directly ablated via phase transition without passing through a molten state, preventing thermal conduction to surrounding regions and eliminating the heat-affected zone problem
2Loss of substance
If long laser pulses are used for cutting, then material removal is achieved, but a large heat-affected zone is created
Solution Approach 1:
The patent changes the temporal parameter of laser pulse duration from long (nanosecond or longer) to ultrashort (picosecond). This enables material removal through direct ablation where the pulse duration is shorter than the thermal diffusion time, preventing heat from spreading to surrounding material while still achieving effective material removal
Solution Approach 2:
The patent employs ultrashort picosecond pulses that deliver energy so rapidly they 'rush through' the material-focusing energy deposition faster than thermal diffusion can occur. This allows material removal to proceed before heat can spread to surrounding areas, eliminating heat-affected zones while maintaining cutting effectiveness
3Ease of manufacture
If conventional laser cutting is used, then glass separation is achieved, but thermal stress causes cracking of the glass surface
Solution Approach 1:
The patent changes the laser pulse duration parameter to ultrashort picosecond pulses, which deposit energy so rapidly that thermal stress and shock waves are minimized. The extremely short interaction time prevents the buildup of thermal gradients that cause cracking, while still achieving effective glass separation through controlled ablation
Solution Approach 2:
The patent replaces the thermal-mechanical separation mechanism (relying on thermal stress-induced crack propagation) with a direct ablation mechanism. Instead of using heat to create stress and separate glass, the ultrashort laser pulses directly remove material through ablation, eliminating the thermal stress cracking problem inherent in conventional thermal separation methods
4Ease of manufacture
If conventional laser cutting techniques are used, then cutting is achieved, but control of cut depth within tens of microns is difficult
Solution Approach 1:
The patent changes the laser pulse duration to ultrashort picosecond pulses, which enables precise control of energy deposition depth. The ultrashort duration confines energy deposition to a very shallow region, and by controlling pulse energy and number of pulses, the cut depth can be precisely controlled within tens of microns or even finer, achieving high manufacturing precision while maintaining cutting capability
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
Achieves precise and controlled separation of glass sheets with minimal sub-surface damage and debris, allowing for high precision cutting and reuse of carrier substrates.
Implementation Method 1
an ultrashort (within a range between 1 picosecond and 100 picoseconds) pulse laser beam is focused to an energy density above the threshold needed to create a defect in the region of focus
Implementation Method 2
followed by a CO2 laser for thermal stress to facilitate controlled separation
Implementation Method 3
A reflective layer may be formed by depositing a thin material (aluminum, copper, silver, gold, etc). A reflective layer is preferential as it scatters the incident energy
Implementation Method 4
A reflective or absorptive layer is formed between the transparent material and carrier substrate
Data Source
Figure 1~2B
Figure 3A
Figure 3B-1~3B-4
AI summary
The embodiments disclosed herein relate to methods, systems, and system components for creating and arranging small (micron and smaller) defects or perforations in transparent materials in a particular manner, and, more particularly, to the arrangement of these defects, each of which has an average crack length, in a predetermined spaced-apart relation (each defect separated from an adjacent defect by a predetermined distance) defining a contour in a transparent material to lower the relative interface fracture toughness for subsequent planned induced separation.