Optical Waveguide Laser Singulation for Crack-Free Contour Cutting
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Solution Overview
Problem
Traditional methods for cutting optical substrates using milling or water jets introduce stresses that can cause substrate pieces to separate along unintended paths, leading to stress cracks and fractures, and result in reduced yield.
Innovation Solution
The method involves directing multiple laser beams onto an optical waveguide material to generate perforations on both sides, creating a perforation zone at the contour, which is then used to singulate the material with reduced stress and increased precision, allowing for complex shapes and critical optical alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional milling or water jet methods are used to cut optical substrates, then cutting can be performed, but stresses are introduced in the substrate causing pieces to separate along unintended paths
Solution Approach 1:
The patent replaces traditional mechanical cutting methods (milling) and water jet methods with a laser-based system. The laser beams create perforations and generate stresses that guide fracture along the desired contour, eliminating the substrate stress problems associated with mechanical and water jet cutting methods.
Solution Approach 2:
The patent changes the physical parameters of the cutting process by using laser energy instead of mechanical force or water pressure. By controlling laser beam parameters (intensity, duration, positioning) and managing thermal stress parameters, the system achieves precise singulation without introducing harmful stresses that cause unintended separation paths.
2Productivity
If traditional cutting methods are used, then material can be removed, but substrate stress causes stress cracks and fractures along preferential crystalline internal structure
Solution Approach 1:
The laser-based system replaces mechanical and water jet removal methods, achieving material removal through controlled ablation and stress-induced fracture. This substitution eliminates the introduction of substrate stresses that lead to stress cracks and fractures along the preferential crystalline internal structure.
Solution Approach 2:
The laser beams act as an intermediary that transfers energy to the substrate to create perforations and controlled stresses. This intermediary mechanism allows material removal and singulation without directly applying mechanical forces that would compromise substrate integrity and cause stress cracks.
3Device complexity
If single-sided laser perforation is used, then process complexity is reduced, but singulation precision and stress control are insufficient
Solution Approach 1:
The patent segments the laser processing into multiple independent laser beams operating on different sides of the substrate. Each laser beam performs a specific function (creating perforations, generating stresses) and the combined effect of multiple beams achieves precise singulation with better stress control than a single beam could provide.
Solution Approach 2:
The patent transitions from single-sided to multi-sided laser processing, adding a spatial dimension to the process. By directing laser beams from opposite sides of the substrate, the system creates a more balanced stress distribution and achieves superior singulation precision while maintaining manageable device complexity.
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 reduces wafer-level stress, minimizes fractures, and increases process yield by enabling the manufacture of optical waveguides with enhanced visual qualities and performance, particularly for monocular or binocular headsets, by precisely controlling the singulation process.
Implementation Method 1
A first laser beam is directed onto a first side of the optical waveguide material to generate a first group of perforations in the optical waveguide material
Implementation Method 2
A second laser beam is directed onto a second side of the optical waveguide material to generate a second group of perforations in the optical waveguide material
Implementation Method 3
A third laser beam is directed at the perforation zone to singulate the optical waveguide material at the perforation zone
Data Source
AI summary
Methods for singulating an optical waveguide material at a contour include directing a first laser beam onto a first side of the optical waveguide material to generate a first group of perforations in the optical waveguide material. A second laser beam is directed onto a second side of the optical waveguide material to generate a second group of perforations in the optical waveguide material. The second side is opposite the first side. The first group of perforations and the second group of perforations define a perforation zone at the contour. A third laser beam is directed at the perforation zone to singulate the optical waveguide material at the perforation zone.