Low-Density Glass Composition for Warp-Resistant Thin Substrates
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Solution Overview
Problem
Existing glass substrates for displays and electronic devices face challenges with warpage due to high film thickness in large-sized displays, leading to increased production costs and load on manufacturing facilities, as well as requirements for high Young's modulus, low alkali ion diffusion, and chemical durability.
Innovation Solution
A glass composition with a density of 2.60 g/cm3 or lower, Young's modulus of 88 GPa or more, strain point of 650 to 720°C, and specific elastic modulus of 34 MN·m/kg or higher, containing 50 to 80% SiO2, 8 to 20% Al2O3, and controlled amounts of alkali metal oxides, P2O5, and other oxides to balance thermal expansion, chemical durability, and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the Young's modulus of glass is increased to reduce warpage in large-sized displays, then substrate deformation is reduced, but the load on manufacturing facilities and production cost increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition of the glass substrate, specifically limiting alkali metal oxide content to 0.01-5 mol% and incorporating specific amounts of Al2O3 (10-30 mol%), B2O3 (5-20 mol%), and other oxides. This compositional parameter optimization achieves the desired Young's modulus without excessively increasing manufacturing difficulty, resolving the contradiction between substrate stability and ease of manufacture
Solution Approach 2:
The patent employs composite material design by creating a multi-component glass system that combines SiO2, Al2O3, B2O3, and controlled amounts of alkali metal oxides and other additives. This composite approach allows tuning of the Young's modulus to reduce warpage while maintaining formability and reasonable manufacturing conditions, balancing substrate performance with manufacturing feasibility
2Weight of moving object
If the glass is thinned to reduce display weight, then weight is reduced, but chemical durability and strength may deteriorate
Solution Approach 1:
The patent uses parameter changes by optimizing the chemical composition to achieve high strength and chemical durability despite reduced thickness. Specifically, controlling alkali metal oxide content and incorporating Al2O3, B2O3, and other oxides in precise proportions enhances the glass matrix structure, improving both mechanical strength and chemical resistance to enable thin substrate design without sacrificing reliability
3Ease of manufacture
If alkali metal oxide content is increased to improve formability, then ease of manufacture is improved, but alkali ion diffusion into thin films increases causing deterioration of film properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the alkali metal oxide content within 0.01-5 mol%, optimizing the balance between formability and film property preservation. This controlled composition allows sufficient ease of manufacture while minimizing alkali ion diffusion into thin films, maintaining film quality
Solution Approach 2:
The patent introduces intermediary substances such as Al2O3, B2O3, and other oxides that act as mediators between the glass matrix and thin films. These intermediaries improve the overall glass structure and formability while preventing harmful alkali ion diffusion into sensitive thin film layers, resolving the contradiction between manufacturability and film integrity
4Stability of the object's composition
If the strain point is increased to minimize glass deformation at high temperature, then thermal stability is improved, but the glass becomes harder to form
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition to achieve an optimal strain point range. By controlling the content of Al2O3, B2O3, and other oxides, the glass attains sufficient thermal stability to minimize deformation during manufacturing and operation, while maintaining adequate formability through balanced composition design
Data Source
AI summary
A glass has a density of 2.60 g/cm3 or lower, a Young's modulus of 88 GPa or more, a strain point of 650 to 720° C., a temperature T4 at which a glass viscosity reaches 104 dPa·s of 1,320° C. or lower, a glass surface devitrification temperature (Tc) of T4+20° C. or lower, and an average coefficient of thermal expansion of 30×10−7 to 43×10−7/° C. at 50 to 350° C. The glass contains, as represented by mol % based on oxides, 50 to 80% of SiO2, 8 to 20% of Al2O3, 0 to 0.5% in total of at least one kind of alkali metal oxide selected from the group consisting of Li2O, Na2O and K2O, and 0 to 1% of P2O5.