Lead-Free Glass Composition for Low-Temperature Sealing
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Solution Overview
Problem
The Ag2O-V2O5-TeO2 system lead-free glass composition has a low softening point, but it is challenging to further lower it without risking crystallization, especially when compounded with ceramic and metal particles, making it difficult to develop into glass composite materials and applications for sealing and electronic components.
Innovation Solution
A lead-free glass composition containing silver oxide, tellurium oxide, and vanadium oxide, with additional components like yttrium oxide, lanthanum oxide, and others, is formulated to reduce crystallization tendency and lower the softening point to below the melting point of tin, achieving a balanced chemical stability and low-temperature softening liquidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the softening point of lead-free glass composition is lowered to achieve low-temperature softening liquidity, then the softening temperature decreases, but crystallization tendency increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of Ag2O (10-60 mass%), V2O5 (5-65 mass%), and TeO2 (15-50 mass%) within the glass system. By adjusting these compositional parameters and their interactions, the glass achieves a softening point of 268-320°C while suppressing crystallization through the synergistic effect of multiple oxides rather than relying on a single low-melting component.
Solution Approach 2:
The patent employs composite materials by creating a multi-component glass system combining Ag2O-V2O5-TeO2 with additional oxides (P2O5, BaO, K2O, WO3, Fe2O3, MnO2, Sb2O3, ZnO). This composite approach allows the glass to achieve low softening temperature through the V2O5-TeO2 combination while the Ag2O and other oxides work together to suppress crystallization and maintain compositional stability.
2Temperature
If lead oxide is used to achieve low softening point and good softening liquidity, then the softening temperature decreases to 350-400°C, but environmental safety deteriorates due to lead being a banned substance
Solution Approach 1:
The patent applies the extraction principle by completely removing lead oxide (PbO) from the glass composition system. The low-melting glass achieves softening at 268-320°C through alternative oxide combinations, specifically using V2O5-TeO2 as the primary low-melting mechanism while Ag2O and other oxides provide structural stability and suppress harmful crystallization.
Solution Approach 2:
The patent implements parameter changes by substituting the chemical composition parameters - replacing PbO with a multi-oxide system where Ag2O (10-60 mass%), V2O5 (5-65 mass%), and TeO2 (15-50 mass%) work in combination. This compositional parameter change achieves comparable or superior softening performance (268-320°C vs 350-400°C) while eliminating environmental harm from lead.
3Temperature
If the glass composition is softened at lower temperature to achieve good softening liquidity, then the processing temperature decreases, but chemical stability deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the compositional parameters of multiple oxides simultaneously. The Ag2O-V2O5-TeO2 system with additional oxides creates a glass composition that softens at 268-320°C while maintaining chemical stability through the synergistic network formed by these components, particularly the role of Ag2O and V2O5 in structuring the glass matrix at low temperatures.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide systems (Ag2O-V2O5-TeO2 with P2O5, BaO, K2O, WO3, Fe2O3, MnO2, Sb2O3, ZnO) to create a glass that achieves low-temperature softening while maintaining chemical stability. The composite structure allows different oxides to perform specialized functions: V2O5-TeO2 for low melting, Ag2O for stability enhancement, and other oxides for supplementary structural support and crystallization suppression.
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 solution provides a lead-free glass composition with a low softening point equal to or lower than 200°C, suppressing crystallization and maintaining high chemical stability, suitable for use in electronic components and sealing structures without environmental harm.
Implementation Method 1
Upon sealing, bonding or the like, the glass composite material or glass paste is tightly bonded to a sealed member, a bonded member or the like, by softening and flowing of the low-melting glass composition contained in the glass composite material or the glass paste.
Implementation Method 2
the glass composite material is also used as a conductive junction for electrical conduction or a heat dissipation junction for thermal conduction
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3
AI summary
The purpose of the present invention is to provide a lead-free glass composition in which crystallization is suppressed and which has a low softening point. This lead-free glass composition is characterized by containing silver oxide, tellurium oxide and vanadium oxide, and further containing at least one compound selected from among yttrium oxide, lanthanum oxide, cerium oxide, erbium oxide, ytterbium oxide, aluminum oxide, gallium oxide, indium oxide, iron oxide, tungsten oxide and molybdenum oxide as an additional component, and in that the content values (mol%) of silver oxide, tellurium oxide and vanadium oxide satisfy the relationships Ag2O > TeO2 ≥ V2O5 and Ag5O ≤ 2V2O5 when calculated in terms of the oxides, and in that the content of TeO2 is 25-37 mol.%.