Alkali-Free Glass Composition for Low Devitrification and High Modulus

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Solution Overview

Problem

Existing alkali-free glass compositions face challenges in achieving low crystal growth rates and high productivity while maintaining high strain points and devitrification temperatures, leading to manufacturing difficulties and potential substrate defects.

Innovation Solution

Alkali-free glass compositions with specific oxide ratios, including SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, optimized to achieve a Young's modulus of 83 GPa or higher, crystal growth rate of 100 μm/hr or lower, and devitrification viscosities of 104.2 dPa·s or higher, along with controlled thermal expansion and density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If glass composition is optimized for high strain point and devitrification temperature, then manufacturing difficulty increases and productivity decreases

Engineering Contradiction:

Improvestrain pointVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the composition ranges of multiple oxides (SiO2: 67-73%, Al2O3: 10-16%, B2O3: 0-5%, MgO: 0.1-15%, CaO: 0.1-12%, SrO: 0-8%, BaO: 0-6%) and enforcing specific ratio constraints ([MgO]/[CaO] ≤ 1.5, Formula A ≥ 82.5, Formula B between 690-800, Formula C ≤ 100, Formula D ≤ 20) to achieve optimal balance between strain point, devitrification temperature, and manufacturing ease

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining multiple oxide components in specific proportions to create a glass composition that achieves high strain point (≥690°C) and high devitrification temperature (≥1320°C) while maintaining low crystal growth rate (≤100 μm/hr) and good formability

Inventive Principle:

Principle #40Composite materials

2Reliability

If glass composition is optimized for high devitrification temperature, then crystal growth rate increases causing manufacturing difficulties

Engineering Contradiction:

Improvedevitrification temperatureVSAvoidcrystal growth control

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the composition ranges of multiple oxides and enforcing specific ratio constraints (Formula B between 690-800, Formula C ≤ 100, Formula D ≤ 20) to achieve high devitrification temperature while maintaining low crystal growth rate

Inventive Principle:

Principle #35Parameter changes

3Strength

If Young's modulus is increased to reduce substrate warp, then glass formability decreases

Engineering Contradiction:

ImproveYoung's modulusVSAvoidformability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the composition ranges of multiple oxides and enforcing Formula A ≥ 82.5 to achieve high Young's modulus (≥83 GPa) while maintaining good formability through controlled devitrification characteristics

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12540096B2Alkali-free glass

Publication Date: 2026.02.03 AGC INC

AI summary

An alkali-free glass includes, in mol % in terms of oxides: SiO2: 63-75%; Al2O3: 10-16%; B2O3: 0-5%; MgO: 0.1-15%; CaO: 0.1-12%; SrO: 0-8%; and BaO: 0-6%. [MgO]/[CaO] is 1.5 or smaller. A value of Formula (A) is 82.5 or larger. A value of Formula (B) is 690 or larger and 800 or smaller. A value of Formula (C) is 100 or smaller. A value of Formula (D) is 20 or smaller. The alkali-free glass has a Young's modulus of 83 GPa or larger and a surface devitrification viscosity ηc of 104.2 dPa·s or higher.