Glass Magnetic Disk Substrate for Low-Vibration Thin HDD Media
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Solution Overview
Problem
The increase in magnetic disk diameter and reduction in thickness lead to increased vibration and particle formation due to external impacts, which can hinder data storage capacity and reliability in hard disk drives.
Innovation Solution
A glass substrate for magnetic disks with specific dimensions and material properties, including a diameter of 85-100 mm, thickness of 0.3-0.5 mm, and Young's modulus of 90 GPa or more, is designed to minimize vibration-induced particle formation by controlling amplitude and contact during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diameter of the substrate is increased and the thickness is reduced to increase storage capacity, then the number of magnetic disks per HDD increases, but the rigidity of the substrate decreases and vibration increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness parameter (0.3-0.5mm) and material properties (Young's modulus ≥90 GPa, Q-value ≤1500) to achieve the optimal balance between rigidity and flexibility. This allows the substrate to be thin enough to accommodate more disks while remaining rigid enough to withstand external impacts without excessive vibration.
2Quantity of substance
If the thickness of the substrate is reduced to increase storage capacity, then more magnetic disks can be incorporated, but the substrate becomes more susceptible to external impacts and vibration
Solution Approach 1:
The patent employs composite material principles by selecting glass substrates with specific compositional characteristics (silica content, alkali metal oxide content) that provide both thinness and impact resistance. The controlled composition creates a material that maintains structural integrity during external impacts while allowing sufficient thinness for high storage capacity.
Solution Approach 2:
The patent changes material parameters by specifying Young's modulus ≥90 GPa and Q-value ≤1500, which fundamentally alters the mechanical behavior of the substrate. These parameter changes enable the thin substrate to resist external impacts effectively while maintaining the thickness reduction necessary for high storage capacity.
3Quantity of substance
If the substrate thickness is reduced to increase the number of disks, then storage capacity increases, but particle formation due to vibration increases
Solution Approach 1:
The patent changes the Q-value parameter to ≤1500, which fundamentally alters the vibration characteristics of the substrate. This parameter change reduces the amplitude and duration of vibrations during external impacts, thereby minimizing particle formation while maintaining the thin substrate design necessary for high storage capacity.
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 glass substrate effectively suppresses particle formation and enhances storage capacity by reducing substrate thickness while maintaining rigidity, thus improving HDD reliability and data integrity.
Implementation Method 1
the rigidity of the substrate decreases, large vibration is likely to occur
Implementation Method 2
vibration caused by an external impact in this manner attenuates over time
Data Source
AI summary
A glass substrate for a magnetic disk has a disk shape. The glass substrate has a diameter D of 85 mm or more and 100 mm or less, and a thickness T of 0.3 mm or more and 0.5 mm or less. Regarding a Young's modulus E and the thickness T of the glass substrate, a value of E·T3 is 3 to 18 (GPa·mm3). A material of the substrate has a Q-value of 1500 or less under conditions of 3000 Hz and room temperature. The glass of the glass substrate has a glass transition point of 680° C. or higher.