Glass Substrate Edge Defect Patterning for Stable Laser Separation
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Solution Overview
Problem
Existing methods for manufacturing glass substrates using laser beams struggle to securely separate and remove inner edge portions from glass blanks while maintaining low surface roughness, leading to potential re-bonding of separated cracks and increased risk of cracking during processing of thin substrates.
Innovation Solution
The method involves intermittently forming defects such as holes or glass alterations on the outer and inner circumferential edges of a glass blank using a laser beam, followed by selective heating to create thermal expansion gaps between these edges, allowing for secure separation of the glass substrate without re-bonding of cracks, and subsequent polishing to achieve the required surface roughness.
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 portion can be separated from the glass substrate, but the portion cannot be sufficiently stably taken out and may be bonded again with heat
Solution Approach 1:
A defect line is formed in advance using laser beam irradiation before heating. This preliminary action creates a predetermined path that guides crack development during subsequent heating, ensuring the separated portion follows the intended trajectory and prevents random cracking or re-bonding
Solution Approach 2:
The separation process is divided into two distinct stages: first forming a defect line through laser irradiation, then heating to cause crack development along that defect line. This segmentation ensures controlled separation while preventing re-bonding by maintaining the defect line as a permanent separation guide
2Length of moving object
If the thickness of glass substrates is reduced, then the substrate becomes thinner and more suitable for certain applications, but cracking is likely to occur during processing
Solution Approach 1:
A defect line is formed in advance using laser beam irradiation before heating. This preliminary action creates a predetermined path that guides crack development during subsequent heating, ensuring the separated portion follows the intended trajectory and prevents random cracking or re-bonding
Solution Approach 2:
The defect line is formed at specific locations where separation is desired, creating localized changes in the glass structure. This allows thin substrates to be separated controllably at specific points without compromising the overall integrity of the substrate during processing
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 the secure separation and efficient manufacturing of glass substrates with reduced surface roughness, preventing re-bonding of cracks and minimizing cracking risks during the processing of thin substrates, thus enhancing the production of glass substrates for magnetic disks.
Implementation Method 1
a focal line of a pulsed laser beam is directed to a plurality of positions within the substrate so that the pulsed laser beam is absorbed by the glass substrate at the plurality of positions and a defect line constituted by through-holes is formed on a predetermined first path
Implementation Method 2
the glass substrate is heated along the first path to cause cracks to develop and separate a portion on an inner side of the first path from the glass substrate
Data Source
AI summary
A glass substrate includes a pair of main surfaces, and an outer circumferential edge surface. The outer circumferential edge surface has a circular shape. A plurality of portions each of which has a defect, a hole, or glass alteration and extends in a thickness direction of the glass substrate are intermittently formed on the outer circumferential edge surface along a circumferential direction. The outer circumferential edge surface has a roundness not larger than 15 μm.