Glass Composition for High-Definition Displays
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Solution Overview
Problem
The challenge is to develop a glass suitable for high-definition displays, particularly for OLED and liquid crystal displays driven by LTPS or oxide TFTs, which requires high devitrification resistance, high strain point, high Young's modulus, low thermal shrinkage, and chemical resistance, while minimizing alkaline content and maintaining excellent meltability and thermal expansion coefficients matching those of semiconductor films.
Innovation Solution
A SiO2-Al2O3-B2O3-RO-based glass composition with optimized contents of SiO2, Al2O3, B2O3, and RO, where specific crystal phases precipitate within a controlled temperature range, enhancing strain point, Young's modulus, and devitrification resistance, and minimizing Li2O+Na2O+K2O content to prevent alkali ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the contents of Al2O3 and MgO are increased to increase the strain point and Young's modulus, then the strain point and Young's modulus are improved, but the forming temperature increases and devitrified foreign matter is generated
Solution Approach 1:
The patent optimizes the chemical composition parameters of the glass, specifically controlling the content ratios of Al2O3, MgO, and B2O3 to achieve the desired strain point and Young's modulus without excessively increasing the forming temperature. By adjusting these compositional parameters within specific ranges, the glass properties are improved while maintaining manufacturability.
Solution Approach 2:
The patent uses a composite glass system comprising multiple oxides (SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, and optional components) where the synergistic interaction between components achieves high strain point and Young's modulus. The composite composition allows the glass to attain desired mechanical properties without requiring excessive amounts of any single high-melting-point component, thus avoiding excessive forming temperature increases.
2Strength
If the contents of Al2O3 and MgO are increased to increase the strain point and Young's modulus, then the strain point and Young's modulus are improved, but devitrified foreign matter is generated
Solution Approach 1:
The patent carefully controls the compositional parameters and cooling rates to prevent devitrification. By optimizing the ratio of Al2O3 to B2O3 and maintaining specific content ranges, the glass remains stable against crystallization even when Al2O3 and MgO contents are increased to improve Young's modulus.
Solution Approach 2:
The patent utilizes controlled crystallization of specific phases (such as anorthite or mullite) in predetermined amounts and sizes, converting the potential harmful effect of devitrification into a beneficial reinforcement mechanism. These controlled crystals act as strengthening phases while maintaining glass transparency and stability.
3Ease of manufacture
If the glass contains alkaline component at high content, then the meltability is improved, but alkali ion diffusion into semiconductor film causes degradation in film characteristics
Solution Approach 1:
The patent extracts or removes the harmful alkaline components (Na2O, K2O) from the glass composition, using alternative alkaline earth metal oxides (MgO, CaO, SrO, BaO) that do not cause ion diffusion into the semiconductor film. This extraction of harmful elements maintains meltability through alternative mechanisms while eliminating the degradation effect on film characteristics.
Solution Approach 2:
The patent replaces permanent harmful alkaline components with alternative oxides that serve the meltability function temporarily during manufacturing but do not migrate into the device structure. The alternative components remain stable in the glass matrix and do not cause long-term degradation like traditional alkalines do.
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 optimized glass composition achieves high devitrification resistance, high strain point, and high Young's modulus, ensuring stable display performance with reduced thermal shrinkage and chemical resistance, suitable for large-area, thin-film displays with improved manufacturing efficiency and reduced defects.
Implementation Method 1
a glass having a property of allowing two or more kinds of crystals selected from a SiO2-Al2O3-RO-based crystal, a SiO2-based crystal, and a SiO2-Al2O3-based crystal to precipitate in a temperature range of from a liquidus line temperature to (the liquidus line temperature-50°C.)
Data Source
AI summary
A glass composition SiO2, Al2O3, B2O3, and RO, where RO represents one kind or two or more kinds selected from MgO, CaO, SrO, and BaO, and allows two or more kinds of crystals selected from a SiO2—Al2O3—RO-based crystal, a SiO2-based crystal, and a SiO2—Al2O3-based crystal to precipitate in a temperature range of from a liquidus line temperature to (the liquidus line temperature—50° C.)