Laser Separation of Brittle Material Using Controlled Release Cracks
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Solution Overview
Problem
Existing methods for laser-cutting brittle materials, such as glass and ceramics, often result in residual bonding issues, especially with curved sections, leading to incomplete separation and rough edges, which require additional processing steps and mechanical stress to achieve clean cuts.
Innovation Solution
The method employs a dual-laser system where a focused beam of pulsed laser-radiation creates defects along a cutting line, and a second laser with a different wavelength is used to heat specific release features, such as straight and circular patterns, to induce controlled cracking and separation of the cut item from the workpiece, minimizing additional apparatus and processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focused beam of pulsed laser-radiation is used to create defects along a cutting line, then manufacturing precision is improved, but the cut article remains physically inhibited from separating due to residual bonding and stiction
Solution Approach 1:
The patent applies preliminary action by creating defects along the cutting line before separation. The first laser beam pre-damages the material structure by creating micro-cracks and defects that weaken the bonding, making subsequent separation easier. This preliminary defect creation prepares the material for easier separation without requiring excessive force later.
Solution Approach 2:
The patent replaces mechanical stress application with a second laser beam for separation. Instead of applying mechanical force to break the residual bonding, a second laser beam with different wavelength is used to induce thermal stress and create additional defects that propagate cracks along the cutting line, achieving separation without mechanical contact.
2Ease of operation
If mechanical stress is applied to cause separation along the cutting line, then separation is achieved, but unwanted defects such as chips and micro-cracks are generated
Solution Approach 1:
The patent substitutes mechanical stress with optical-thermal energy for separation. The second laser beam delivers energy that creates thermal gradients and induces cracking through thermal stress rather than mechanical force. This non-contact method achieves separation while avoiding the chip and micro-crack defects associated with mechanical stress application.
Solution Approach 2:
The patent changes the physical parameter from mechanical stress to thermal energy for the separation step. By using a second laser beam with a wavelength absorbed by the material, thermal energy is converted to mechanical stress through thermal expansion and gradients, creating controlled cracking without the harmful effects of direct mechanical contact.
3Reliability
If relief lines are added to curved sections of the cutting line, then separation control is improved, but device complexity and processing time increase
Solution Approach 1:
The patent uses the second laser beam to induce cracking along the entire cutting line including curved sections without requiring additional relief lines. The thermal stress and defect propagation mechanism naturally follows the cutting line geometry, eliminating the need for complex relief line patterns and reducing overall process complexity.
Solution Approach 2:
The second laser beam serves multiple functions: it separates straight sections and induces cracking in curved sections without requiring different approaches. This universal separation mechanism works for all cutting line geometries, eliminating the need for special relief line treatments for curved sections and simplifying the overall process.
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 reliable and clean separation of articles with rounded shapes from brittle materials, reducing surface roughness and stiction, thereby facilitating efficient and precise cutting with minimal additional processing, even for complex geometries.
Implementation Method 1
Transparent brittle materials interact with focused beams of pulsed laser-radiation through non-linear absorption of the laser-radiation
Implementation Method 2
The absorbed laser-power creates a thermal gradient across the cutting line, which causes cracks to propagate between the discrete defects produced by the pulsed laser-radiation
Implementation Method 3
a second laser with a different wavelength is used to heat specific release features, such as straight and circular patterns, to induce controlled cracking and separation
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A method for cutting and separating an item (102) from a workpiece (12) made of a brittle material is disclosed. The method uses straight and circular release features (112A, 112B) that are arranged to cause controlled cracking in scrap material (104) close to each inside curve in the outline of the item (102). A first pulsed laser-beam (14) weakens material along the outline of the item (102) and along the release features (112A, 112B). A second laser-beam (40) selectively heats the release features (112A, 112B) for sufficient time to cause melting and deformation, thereby initiating the controlled cracking.