Glass Substrate Separation Using Laser Defects and Thermal Expansion
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Solution Overview
Problem
Existing methods for manufacturing glass substrates using laser beams struggle to securely separate and remove inner edge surfaces with reduced surface roughness, leading to potential re-bonding of cracks and inefficiencies in thin substrate processing.
Innovation Solution
A method involving the formation of defects on glass blanks using laser beams, followed by controlled thermal expansion to create gaps between outer and inner portions, ensuring secure separation and reducing surface roughness, particularly using concentric circular laser irradiation and selective heating to prevent re-bonding of cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the glass substrate is heated along the first path to cause cracks to develop and separate the portion on the inner side, then the separation is achieved, but the portion cannot be securely taken out due to re-bonding of cracks
Solution Approach 1:
The patent applies thermal expansion by heating the portion on the outer side of the first path to a temperature higher than that of the portion on the inner side. This temperature difference causes differential thermal expansion where the outer portion expands more than the inner portion, creating and maintaining a gap that prevents crack re-bonding and enables secure separation of the inner portion.
2Productivity
If a laser beam is used to form defects and separate the glass substrate, then manufacturing efficiency is improved, but cracking is likely to occur during processing of thin substrates
Solution Approach 1:
The patent applies local quality by forming defects locally along a specific path through the glass substrate using a laser beam, rather than uniformly treating the entire substrate. This localized defect formation allows controlled separation along the desired path while minimizing damage to other areas, and the subsequent selective heating further localizes thermal effects to prevent unwanted cracking.
Solution Approach 2:
The patent applies parameter changes by controlling the temperature distribution across the glass substrate, heating the outer portion to a higher temperature than the inner portion. This temperature parameter change creates differential thermal expansion that enables clean separation while preventing crack propagation in other areas, thus maintaining substrate integrity outside the separation zone.
3Manufacturing precision
If the inner edge surface roughness is reduced using laser processing, then the surface quality is improved, but the separation and removal of the inner portion becomes unstable
Solution Approach 1:
The patent applies preliminary action by first forming defects along the separation path using a laser beam before performing the actual separation through selective heating. This preliminary defect formation creates a predetermined separation path with reduced surface roughness on the inner edge surface, and the subsequent heating step reliably follows this pre-established path, ensuring stable and reproducible separation.
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 allows for the secure separation and efficient production of glass substrates with reduced surface roughness, minimizing re-bonding of cracks and enhancing the manufacturing of thin glass substrates for magnetic disks.
Implementation Method 1
forming a defect on a line having a predetermined annular shape in a surface of a glass blank by irradiating the line with a laser beam
Implementation Method 2
heating the outer portion more than the inner portion to cause thermal expansion of the outer portion relative to the inner portion and form a gap
Data Source
AI summary
A method for manufacturing a glass substrate including an opening includes forming lines of inner and outer circumferential portions irradiated with a laser beam along substantially concentric circles in a surface of a glass blank, separating a portion on an inner side of the line of the outer circumferential portion of the glass blank and a portion on an outer side of the line of the outer circumferential portion from each other by heating the portion on the outer side of the line of the outer circumferential portion with radiant heat, and separating a portion on an inner side of the line of the inner circumferential portion of the glass blank and a portion on an outer side of the line of the inner circumferential portion from each other by heating the portion on the outer side of the line of the inner circumferential portion with radiant heat.