Disc-Shaped Glass Substrate Scribing on Flattened Laser Paths
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Solution Overview
Problem
Conventional methods for manufacturing glass substrates for magnetic disks face challenges in reliably separating an annular glass substrate from a glass blank, particularly due to surface roughness issues that affect the formation of defects necessary for thermal separation.
Innovation Solution
A method involving the use of laser beams to flatten and form scribe lines on the glass blank, reducing surface roughness to enable precise separation by thermal expansion differences between outer and inner portions, with post-processing steps to refine the edges and surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser beam is used to form defects along a predetermined ring shape on the glass blank surface, then defects are formed to enable thermal separation, but the surface roughness prevents reliable defect formation and separation
Solution Approach 1:
The patent applies preliminary action by performing surface flattening treatment with a first laser beam before forming defects with a second laser beam. This preliminary flattening step reduces surface roughness to 0.2 μm or less, creating optimal conditions for subsequent defect formation and ensuring reliable thermal separation. The flattening is performed in advance along the predetermined ring shape where defects will be formed.
Solution Approach 2:
The patent replaces conventional mechanical surface flattening methods with laser-based flattening treatment. The first laser beam irradiates the glass blank surface to melt and resurface the rough areas, achieving precise surface flattening without mechanical contact. This substitution enables better control over surface roughness and prepares the surface for reliable defect formation.
2Reliability
If the outer portion of the glass blank is heated at a higher temperature to cause thermal expansion for separation, then separation is achieved, but the process is unreliable due to surface roughness affecting defect formation
Solution Approach 1:
The patent performs surface flattening as a preliminary action before defect formation. By reducing surface roughness to 0.2 μm or less using the first laser beam, the glass surface becomes suitable for reliable defect formation by the second laser beam. This preliminary preparation ensures that the subsequent thermal expansion and separation process proceeds reliably.
Solution Approach 2:
The patent changes the surface roughness parameter from its original state to 0.2 μm or less through laser flattening treatment. This parameter change makes the glass surface more receptive to defect formation by the second laser beam, enabling reliable separation through thermal expansion without manufacturing difficulties.
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 method enhances the reliability of separating annular glass substrates by ensuring accurate defect formation and surface smoothing, improving the quality and stability of the glass substrates for magnetic disks.
Implementation Method 1
flattening a to-be-scribed region extending along a predetermined to-be-scribed line on a surface of a glass blank by irradiating the surface of the glass blank with a first laser beam along the to-be-scribed line
Implementation Method 2
forming a scribe line along the to-be-scribed line by irradiating the flattened to-be-scribed region with a second laser beam
Implementation Method 3
the outer portion of the glass blank is heated at a temperature higher than the temperature of the inner portion to cause the outer portion of the glass blank to thermally expand relatively largely compared to the inner portion
Data Source
AI summary
A method for manufacturing a glass substrate includes: flattening a to-be-scribed region extending along a predetermined to-be-scribed line on a surface of a glass blank by irradiating the surface of the glass blank with a first laser beam along the to-be-scribed line; and forming a scribe line along the to-be-scribed line by irradiating the flattened to-be-scribed region with a second laser beam.