High Liquidus Viscosity Electronic Glass for Display Substrates
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Solution Overview
Problem
The existing glass substrates used in thin film transistor (TFT) manufacturing for displays have low liquidus viscosity, leading to deformation and breakage during high-temperature processing, which affects production stability and scalability, especially for large-sized displays.
Innovation Solution
The development of electronic glass with optimized composition, including SiO2, Al2O3, B2O3, SrO, BaO, CaO, and MgO, to achieve a liquidus viscosity greater than 200,000 poise, a strain point temperature between 670°C to 739°C, and a Young's modulus of 70 GPa to 83 GPa, ensuring stability and reducing deformation during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the strain point and Young's modulus of glass are increased to prevent substrate deformation during high-temperature processing, then thermal stability is improved, but the liquidus viscosity becomes small, causing crystallization during forming and glass sheet breakage
Solution Approach 1:
The patent applies parameter changes by precisely adjusting the chemical composition parameters of the glass substrate. Specifically, it controls SiO2 content at 65.56-68.6%, Al2O3 at 10.58-14%, B2O3 at 7-11%, and specific ranges for SrO, BaO, CaO, and MgO. This compositional parameter optimization achieves liquidus viscosity >200,000 poise while maintaining strain point of 670-739°C and Young's modulus of 70-83 GPa, resolving the contradiction between thermal stability and production stability.
Solution Approach 2:
The patent employs composite material principles by creating a multi-component glass system that combines oxide components with complementary properties. The glass composition integrates network formers (SiO2, B2O3) with network modifiers (SrO, BaO, CaO, MgO) and intermediates (Al2O3), where each component contributes specific properties. This composite approach allows simultaneous achievement of high liquidus viscosity, appropriate strain point, and sufficient Young's modulus, preventing both deformation and crystallization.
2Speed
If the glass substrate is heated to 500°C or above for laser annealing to crystallize amorphous silicon layer, then electron mobility is improved, but the glass substrate shrinks and deforms
Solution Approach 1:
The patent changes the thermal parameter parameters of the glass substrate by optimizing its chemical composition to achieve strain point of 670-739°C and thermal expansion coefficient of 3.2-3.8×10^-6/K. These parameter changes ensure the glass maintains dimensional stability during laser annealing at 500°C or above, preventing substrate shrinkage and deformation while allowing the amorphous silicon layer to crystallize and achieve high electron mobility.
3Area of moving object
If the glass manufacturing moves toward higher generations to meet large-sized display demand, then display size is increased, but the weight of glass significantly complicates automated conveyors and causes elastic sagging
Solution Approach 1:
The patent applies parameter changes by optimizing the glass composition to achieve density of 2.38-2.45 g/cm3, which is relatively low for display glass. This density optimization, combined with high Young's modulus (70-83 GPa), reduces the weight of large-sized glass substrates and minimizes elastic sagging during transportation and handling, facilitating automated conveyor systems for high-generation display manufacturing.
4Reliability
If the liquidus viscosity of glass is increased to prevent crystallization during forming, then production stability is improved, but the difference between liquidus temperature and forming temperature becomes smaller, reducing process margin
Solution Approach 1:
The patent resolves this contradiction through comprehensive parameter changes in the glass composition. By controlling SiO2 at 65.56-68.6%, Al2O3 at 10.58-14%, B2O3 at 7-11%, and specific ranges for SrO, BaO, CaO, and MgO, the patent achieves liquidus viscosity >200,000 poise while maintaining strain point of 670-739°C. This compositional optimization ensures both high liquidus viscosity for production stability and sufficient temperature margin for forming processability.
Data Source
AI summary
Disclosed are electronic glass having high liquidus viscosity and a preparation method. The proportions of the raw materials used in the electronic glass are: SiO2: 65.56-68.6%; Al2O3: 10.58-14%; B2O3: 7-11%; SrO: 0.27-3.26%; BaO: 7.20-10.12%; CaO: 0.22-1.22%; MgO: 0-1.05%; MgO+CaO+SrO+BaO<13%; and the liquidus viscosity of the electronic glass is greater than 200,000 poise. The minimum value of the temperature corresponding to a liquidus temperature reduction of 100,000 poise in the electronic glass is 22° C. The electronic glass has a strain point temperature of 670-739° C., a Young's modulus of 70-83 GPa, and a density of 2.38-2.45 g/cm3, the liquidus viscosity is ensured to be higher than 200,000 poise, the electronic glass is well suited to overflow downdraw forming, and a relatively low density value can be obtained.