Controlled-Microwaviness Glass Sheets for Magnetic Disk Substrates
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Solution Overview
Problem
Magnetic recording disks require glass substrates with smooth and defect-free surfaces, but existing glass sheets often necessitate costly polishing and lapping processes to achieve this, increasing production costs and efforts.
Innovation Solution
A glass sheet is provided with a controlled surface waviness, characterized by a root mean square microwaviness between 1.2 nm and 2.8 nm, measured using laser Doppler vibrometry, to minimize subsequent processing steps and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional glass sheets are used for magnetic recording disk substrates, then the glass substrates can be produced, but extensive polishing and lapping processes are required to achieve smooth surfaces, increasing production costs and processing efforts
Solution Approach 1:
The glass sheet is pre-conditioned during manufacturing to achieve a controlled micrawaviness range (0.6-3.0 nm RMS) before cutting into substrates. This preliminary surface conditioning eliminates the need for extensive post-processing polishing and lapping, directly reducing manufacturing costs while ensuring the required surface smoothness for magnetic recording disks
2Manufacturing precision
If conventional glass sheets are used for magnetic recording disk substrates, then the glass substrates can be produced, but extensive polishing and lapping processes are required to achieve smooth surfaces, increasing processing efforts
Solution Approach 1:
The glass sheet manufacturing process incorporates preliminary surface conditioning to achieve the target micrawaviness range (0.6-3.0 nm RMS) before the glass sheet is cut into substrates. This advance preparation eliminates multiple subsequent polishing and lapping steps, simplifying the overall manufacturing process while ensuring adequate surface smoothness
Solution Approach 2:
The invention specifies a precise micrawaviness parameter range (0.6-3.0 nm RMS) for the glass sheet surface. By controlling this specific parameter during glass sheet manufacturing, the need for complex multi-step surface processing is eliminated, reducing device complexity while maintaining required surface quality
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
The controlled surface waviness reduces the need for extensive polishing, leading to cost-effective production of magnetic recording disks with reduced processing efforts.
Implementation Method 1
a root mean square of a surface topography of the surface features determined using a surface analysis on the first surface with incident and reflected light
Data Source
AI summary
A glass sheet configured to be cut into glass substrates for magnetic recording disks is described. The glass sheet includes a first surface. For surface features of the first surface with a feature wavelength of 60 to 500 micrometers (μm), a root mean square of a surface topography of the surface features determined using a surface analysis on the first surface with incident and reflected light is given as a microwaviness. A maximum value of the microwaviness of any arbitrary region of the first surface may be between 1.2 nanometers (nm) and 2.8 nm, inclusive of 1.2 nm and 2.8 nm. After the surface analysis, the glass sheet may be cut into the glass substrates in response to determining that the maximum value of the microwaviness is in the noted range. Further, a method of fabricating glass substrates from a glass sheet is described.