Flat Panel Display Glass Substrate Composition for Heat Shrinkage Control
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Solution Overview
Problem
Conventional glass substrates for flat panel displays, particularly those using polysilicon thin-film transistors (p-Si TFTs), face challenges with heat shrinkage during high-temperature processing, leading to non-uniform pixel pitches and limitations in achieving high resolution due to the high strain point and devitrification resistance requirements.
Innovation Solution
A glass substrate composition comprising 55-80% SiO2, 3-20% Al2O3, 3-15% B2O3, and 3-25% RO (MgO, CaO, SrO, BaO) with specific ratios of SiO2, Al2O3, and B2O3, optimized to achieve a strain point of 665°C or more and a devitrification temperature of 1250°C or less, while maintaining low heat shrinkage rates of 75 ppm or less, ensuring uniform pixel pitches and high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the Tg and strain point of the glass are increased to reduce heat shrinkage, then the heat shrinkage rate decreases, but the devitrification resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition ratios of SiO2, Al2O3, and B2O3 in the glass substrate. Specifically, it sets the ratio (SiO2+Al2O3)/B2O3 within 7.5-17 and individual contents within specific ranges, which transforms the glass properties to achieve both high strain point (≥665°C) and adequate devitrification resistance (≤1250°C), thereby resolving the contradiction between reducing heat shrinkage and maintaining devitrification resistance.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components (SiO2, Al2O3, B2O3, and RO) in specific proportions to create a glass composition that achieves both high heat resistance and good devitrification resistance. This composite approach allows the glass to exhibit synergistic properties that cannot be achieved by single components alone.
2Reliability
If the devitrification temperature is increased to improve devitrification resistance, then the devitrification resistance improves, but the liquidus viscosity decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the glass composition parameters, specifically setting the B2O3 content within 3-15% and the ratio (SiO2+Al2O3)/B2O3 within 7.5-17. This transformation of compositional parameters achieves devitrification temperature ≤1250°C while maintaining liquidus viscosity ≥104.0 dPa·s, thereby resolving the contradiction between improving devitrification resistance and maintaining ease of manufacture.
3Productivity
If conventional glass substrates are used for p-Si TFT production, then the production process can proceed, but significant heat shrinkage occurs leading to non-uniform pixel pitch
Solution Approach 1:
The patent applies parameter changes by transforming the glass substrate's thermal properties through compositional optimization. By setting the strain point ≥665°C and controlling the heat shrinkage rate to ≤75 ppm, the glass substrate can withstand p-Si TFT production temperatures while maintaining dimensional stability, thereby achieving both production capability and pixel pitch uniformity.
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 substrate composition effectively reduces heat shrinkage and maintains devitrification resistance, enabling the production of flat panel displays with high resolution and uniform pixel pitches, suitable for polysilicon TFT applications.
Implementation Method 1
the glass substrate undergoes heat shrinkage and heat shock during production of the p-Si TFT
Implementation Method 2
the strain point of the glass is 665° C. or more
Implementation Method 3
the devitrification temperature of the glass is 1250° C. or less
Data Source
AI summary
A flat panel display glass substrate includes a glass comprising, in mol %, 55-80% SiO2, 3-20% Al2O3, 3-15% B2O3, and 3-25% RO (the total amount of MgO, CaO, SrO, and BaO). The contents in mol % of SiO2, Al2O3, and B2O3 satisfy a relationship (SiO2+Al2O3)/(B2O3)=7.5-17. The strain point of the glass is 665° C. or more. The devitrification temperature of the glass is 1250° C. or less. The substrate has a heat shrinkage rate of 75 ppm or less. The rate of heat shrinkage is calculated from the amount of shrinkage of the substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by the rate of heat shrinkage (ppm)={the amount of shrinkage of the substrate after the heat treatment/the length of the substrate before the heat treatment}×106.