Glass Substrate Composition for High-Density Recording Media
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Solution Overview
Problem
Current glass substrates for information recording media face challenges in achieving high recording densities due to surface roughness, chemical durability, and dimensional precision issues, which affect the adhesion of magnetic films and the accuracy of data recording.
Innovation Solution
Development of specific glass compositions, such as those with high SiO2 and Al2O3 content, combined with alkali and alkaline earth metal oxides, that provide enhanced chemical durability, smoothness, and resistance to acidity and alkalinity, along with a method for chemical strengthening to maintain shape stability and prevent alkali metal ion leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass substrate surface smoothness is improved to achieve high recording density, then linear recording density increases, but chemical durability requirements become more stringent making manufacturing more difficult
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass substrate by precisely controlling the content ranges of SiO2 (40-70 mass%), Al2O3 (5-30 mass%), and various metal oxides. This compositional parameter optimization enhances both surface smoothness and chemical durability simultaneously, resolving the contradiction between manufacturing precision and ease of manufacture
Solution Approach 2:
The patent creates a composite glass material system combining multiple oxide components (SiO2, Al2O3, B2O3, P2O5, metal oxides) in specific proportions. This composite composition provides synergistic effects that improve surface smoothness while maintaining chemical durability, allowing high recording density without compromising manufacturing feasibility
2Manufacturing precision
If alkali metal oxides are added to improve glass processing and surface smoothness, then surface quality improves, but alkali metal ion leaching increases reducing chemical durability
Solution Approach 1:
The patent optimizes the concentration parameters of alkali metal oxides (Na2O: 0.1-5 mass%, K2O: 0.1-5 mass%) within strict limits. By controlling these parameters and balancing them with high SiO2 and Al2O3 content, the patent achieves surface smoothness improvement while preventing excessive alkali metal ion leaching, thus maintaining chemical durability
Solution Approach 2:
The patent creates different compositional regions within the glass structure where alkali metal oxides are concentrated in specific phases or regions rather than uniformly distributed. This local quality approach allows surface smoothness enhancement through alkali metal content while limiting overall leaching by confining alkali metals to specific zones within the glass matrix
3Length of moving object
If glass substrate thickness is reduced to meet miniaturization requirements, then device size decreases, but mechanical strength and rigidity deteriorate
Solution Approach 1:
The patent employs a composite glass composition with high SiO2 (40-70 mass%) and Al2O3 (5-30 mass%) content that provides exceptional mechanical strength-to-thickness ratio. This composite material structure enables the substrate to maintain adequate mechanical strength and rigidity even at reduced thickness, satisfying both miniaturization and structural integrity requirements
Solution Approach 2:
The patent modifies the chemical composition parameters to enhance mechanical properties, specifically increasing SiO2 and Al2O3 content while controlling metal oxide additions. These parameter changes improve the intrinsic strength and rigidity of the glass, allowing thickness reduction without compromising mechanical performance
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 proposed glass substrates achieve improved surface smoothness, chemical durability, and dimensional precision, enabling higher recording densities and preventing mechanical errors in data recording, while maintaining the structural integrity and cleanliness of the substrate.
Implementation Method 1
the total content of alkali metal oxides and alkaline earth metal oxides is 3 mass% or more but 20 mass% or less
Implementation Method 2
a method for chemical strengthening to maintain shape stability and prevent alkali metal ion leaching
Data Source
AI summary
According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28. Further provided are the substrate for information recording medium, information recording medium and their manufacturing methods according to the present invention.