Non-Alkali Glass Substrate Composition for LCD Pattern Alignment
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Solution Overview
Problem
In the production of large-sized liquid crystal display panels with relatively low maximum temperatures, pattern misalignment is significant due to warpage of the glass substrate, which is not effectively addressed by reducing the average coefficient of thermal expansion of the glass substrate.
Innovation Solution
An active matrix drive-type liquid crystal display panel is developed using a non-alkali glass substrate with specific compositional ranges for SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, and ZrO2, combined with a metal wiring film and an inorganic insulating film, where the wiring film thickness is 0.1 μm or larger and the insulating film thickness is 100 nm or larger, to suppress warpage and pattern misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the average coefficient of thermal expansion of the glass substrate is decreased, then thermal shrinkage is reduced, but pattern misalignment becomes remarkably large
Solution Approach 1:
The patent changes the physical parameters of the glass substrate by increasing its density and adjusting its thermal expansion characteristics. Specifically, it uses a non-alkali glass with density of 2.4 g/cm³ or more and average coefficient of thermal expansion of 30×10⁻⁷/°C or more, which resolves the contradiction by finding an optimal parameter range that prevents both thermal shrinkage and warpage-induced misalignment
Solution Approach 2:
The patent employs a composite structure combining the glass substrate with metal films (such as Mo, W, or Cu) having specific thermal expansion coefficients. This composite approach allows the system to compensate for thermal effects - the metal films are selected to have thermal expansion coefficients that counterbalance the glass substrate's thermal behavior, thereby maintaining pattern alignment across temperature variations
2Shape
If the density of the glass is decreased, then deflection is suppressed, but manufacturing precision deteriorates
Solution Approach 1:
The patent inverts the conventional approach by increasing the glass density to 2.4 g/cm³ or more. This parameter change suppresses deflection during manufacturing while the accompanying thermal expansion coefficient adjustment (30×10⁻⁷/°C or more) prevents warpage, thereby maintaining both shape stability and manufacturing precision
3Manufacturing precision
If the average coefficient of thermal expansion is reduced, then thermal shrinkage is suppressed, but warpage increases causing pattern misalignment
Solution Approach 1:
The patent identifies and implements an optimal parameter range for the glass substrate: density of 2.4 g/cm³ or more and average coefficient of thermal expansion of 30×10⁻⁷/°C or more. This parameter optimization simultaneously suppresses both thermal shrinkage and warpage, resolving the contradiction between these two deformation modes
Solution Approach 2:
The patent introduces metal films (Mo, W, or Cu) as intermediary layers between the glass substrate and other structures. These metal films act as mediators that compensate for thermal expansion differences and prevent warpage, allowing the use of glass with higher thermal expansion coefficients without suffering from misalignment issues
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 combination of the non-alkali glass substrate and the metal and insulating films effectively reduces warpage and pattern misalignment, enhancing the thermal impact resistance and productivity of the liquid crystal display panel.
Implementation Method 1
the average coefficient of thermal expansion of a substrate glass is decreased, pattern misalignment becomes remarkably large
Implementation Method 2
A second method is to increase a strain point of a glass
Data Source
AI summary
The present invention relates a non-alkali glass, having a Young's modulus (E) of from 70 GPa to 95 GPa and an average coefficient of thermal expansion a from 50° C. to 350° C. of from 32 to 45 (×10−7/° C.), and which satisfies the following formula (1): 20α+7E≥1310. The non-alkali glass has a composition in terms of mol % on the basis of oxides, satisfying the relationship of: 759−13.1×SiO2−7.5×Al2O3−15.5×B2O3+9.7×MgO+21.8×CaO+27.2×SrO+27.9×BaO≥0.