Lead-Free Low-Melting Glass Composition for Low-Temperature Sealing
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Solution Overview
Problem
Conventional lead-free low-melting glass compositions face issues with crystallization during heating and firing, leading to difficulties in sealing and adhesion, and lack sufficient adhesiveness and stickiness, making them unsuitable for applications requiring low-temperature processing.
Innovation Solution
A lead-free low-melting glass composition comprising vanadium oxide, tellurium oxide, silver oxide, and lithium oxide, with specific oxide content ratios that ensure a softening point of 232°C, high adhesiveness, and stickiness, while minimizing crystallization and maintaining chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the softening point of lead-free glass composition is lowered to enable sealing at low temperature, then the sealing temperature can be reduced to around the melting point of tin, but the glass composition becomes prone to crystallization during heating and firing
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxide composition ratios within specific ranges: V2O5 (10-30 mol%), TeO2 (20-40 mol%), Ag2O (15-35 mol%), and Li2O (5-20 mol%). This compositional parameter optimization enables the glass to maintain a softening point of 220°C or lower while achieving a crystallization temperature of 260°C or higher, resolving the contradiction between low sealing temperature and crystallization resistance
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components (V2O5, TeO2, Ag2O, Li2O) in specific proportions to create a lead-free glass composition with synergistic effects. The composite structure of these oxides provides both low softening temperature and high crystallization temperature, preventing crystallization during the sealing process while enabling effective sealing at around the melting point of tin
2Object-affected harmful factors
If lead-free glass composition is used to meet environmental requirements, then compliance with RoHS Directive is achieved, but the glass lacks sufficient adhesiveness and stickiness to substrates
Solution Approach 1:
The patent applies parameter changes by optimizing the oxide composition, particularly incorporating Li2O (5-20 mol%) which enhances adhesiveness, and controlling the ratio of Ag2O and TeO2 to improve wetting properties. These compositional parameters enable the lead-free glass to achieve strong adhesion to substrates while maintaining environmental compliance
Solution Approach 2:
The patent applies local quality by enhancing the interfacial properties of the glass composition at the substrate interface. The specific oxide composition creates improved local chemical interactions and wetting characteristics at the bonding interface, providing sufficient adhesiveness and stickiness without requiring lead content
3Temperature
If the glass composition contains high content of vanadium oxide and tellurium oxide to achieve low softening point, then the softening point is reduced to 220°C or lower, but the chemical stability of the glass is compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration ranges of all oxide components: V2O5 (10-30 mol%), TeO2 (20-40 mol%), Ag2O (15-35 mol%), and Li2O (5-20 mol%). This balanced compositional design achieves a softening point of 220°C or lower while maintaining adequate chemical stability through the synergistic effect of the complete oxide system, preventing any single component from compromising stability
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 composition enables effective sealing and adhesion at low temperatures, with improved softening fluidity, adhesiveness, and chemical stability, meeting environmental safety standards and reducing thermal and environmental impacts.
Implementation Method 1
the low-melting glass composition contained in the low-melting glass composite material or the low-melting glass paste is brought into close contact with the member to be sealed, the member to be adhered or the like by softening and flowing
Implementation Method 2
there is a possibility of crystallization during heating and firing, there remains a problem regarding further lowering the temperature
Data Source
AI summary
A lead-free low-melting glass composition containing vanadium oxide, tellurium oxide, silver oxide and lithium oxide, said composition satisfying the following two relational expressions (1) and (2) in terms of oxides.[Ag2O]≥[TeO2]≥[V2O5]≥[Li2O] (1)2[V2O5]≥[Ag2O]+[Li2O]≥40 (2)(In the formula, [X] represents a content of component X, and the unit thereof is “mol %”; the same applies hereinafter.) Thus, it is possible to provide a lead-free low-melting glass composition which enables sealing and adhesion at around the melting point (232° C.) of tin and which has high adhesiveness and stickiness.