High-Strain-Point Glass Composition for Stable Fusion-Drawn Substrates
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Solution Overview
Problem
Existing glass compositions for liquid crystal displays face challenges in minimizing compaction during high-temperature processing, which affects dimensional stability and leads to misalignment of components, while also being prone to devitrification and electrode corrosion, increasing production costs and complexity.
Innovation Solution
Development of glass compositions with high annealing points, high Young's modulus, and high liquidus viscosities, manufactured through processes like fusion drawing, to minimize compaction and devitrification, ensuring high dimensional stability and reduced stress relaxation, thereby improving the quality of glass substrates for TFTs and other applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If glass substrates are produced by fusion process, then manufacturing efficiency is improved, but compaction occurs during high-temperature processing
Solution Approach 1:
The patent modifies glass composition parameters (adding specific metal oxides like In2O3, Ga2O3, Nb2O5 in controlled amounts) to change the physical and chemical properties of the glass, achieving high strain point and high Young's modulus to prevent compaction during fusion processing
Solution Approach 2:
The patent creates a composite glass system combining multiple oxide components (SiO2, B2O3, Al2O3, In2O3, Ga2O3, Nb2O5, etc.) to achieve synergistic effects that simultaneously provide high strain point, high Young's modulus, and resistance to devitrification
2Reliability
If process temperature is increased for p-Si TFT manufacture, then transistor performance is improved, but compaction increases
Solution Approach 1:
The patent changes the thermal properties of glass by modifying its composition to achieve high strain point, allowing the glass to maintain dimensional stability even when exposed to high processing temperatures required for p-Si TFT manufacture
3Manufacturing precision
If glass composition is modified to increase strain point, then compaction is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent systematically adjusts composition parameters within specific ranges to achieve the desired strain point while maintaining compatibility with existing manufacturing processes, balancing performance improvement with process simplicity
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 glass substrates with high annealing points, high Young's modulus, and high liquidus viscosities, manufactured through processes like fusion drawing, to minimize compaction and devitrification, ensuring high dimensional stability and reduced stress relaxation, thereby improving the quality of glass substrates for TFTs and other applications.
Implementation Method 1
high liquidus viscosities
Implementation Method 2
minimize compaction and devitrification
Implementation Method 3
Compaction, also referred to as thermal stability or dimensional change, is an irreversible dimensional change (shrinkage) in the glass substrate due to changes in the glass fictive temperature
Implementation Method 4
The magnitude of compaction depends both on the process by which a glass is made and the viscoelastic properties of the glass
Implementation Method 5
the fusion process results in very rapid quenching of the glass sheet from the melt, and freezes in a comparatively high temperature structure
Implementation Method 6
Glass that is cooled more slowly, or that is annealed by holding for a time near its annealing point, is said to have a lower fictive temperature
Data Source
AI summary
Substantially alkali free glasses are disclosed with can be used to produce substrates for flat panel display devices, e.g., active-matrix liquid crystal displays (AMLCDs). The glasses have high annealing temperatures and Young's modulus. Methods for producing substantially alkali free glasses using a downdraw process (e.g., a fusion process) are also disclosed.