Vacuum Insulating Glass Edge Seal Using Low-Temperature Solder
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Solution Overview
Problem
Conventional high-temperature bonding techniques for hermetically sealing glass substrates in vacuum insulating glass (VIG) units are unsuitable for heat-sensitive components, as they require bulk heating, which can degrade tempered glass and sensitive materials like OLED devices, and are not environmentally friendly due to the use of lead-based glass frits.
Innovation Solution
A method of forming a metal-inclusive peripheral edge seal using a metallic solder pre-form alloy that reacts to form inter-metallic compounds with pre-coated nickel and silver layers on the glass substrates, allowing for low-temperature processing (up to 250°C) and the use of lead-free alloys, such as SnAgCu, to create a hermetic seal without de-tempering the glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-temperature bonding techniques are used to hermetically seal glass substrates, then sealing reliability is improved, but thermal damage to glass and sensitive components occurs
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature (400-600°C) bonding to low-temperature (room temperature to 200°C) bonding by using a two-stage process: first applying a low-melting-point glass frit layer at low temperature, then applying a high-melting-point glass frit layer that bonds at higher temperature but only locally at the seal interface, not bulk heating the entire assembly
Solution Approach 2:
The patent segments the bonding process into two distinct stages with different temperature requirements: a first bonding stage using low-melting-point glass frit at low temperature for initial sealing, and a second bonding stage using high-melting-point glass frit at higher temperature for final hermetic sealing. This segmentation allows different parts of the structure to experience different temperature histories, protecting heat-sensitive components while achieving reliable seals
2Reliability
If lead-based glass frits are used for hermetic sealing, then sealing performance is improved, but environmental compliance deteriorates
Solution Approach 1:
The patent uses composite glass frit materials consisting of multiple layers with different compositions and melting points. The first layer uses low-melting-point glass frit (lead-free) for initial bonding, and the second layer uses high-melting-point glass frit for final hermetic sealing. This composite approach achieves the sealing performance previously requiring lead-based materials while eliminating environmental harm from lead
3Reliability
If bulk heating is applied to form hermetic seals, then sealing completeness is improved, but energy consumption and thermal damage increase
Solution Approach 1:
The patent applies heating locally only at the seal interface rather than bulk heating the entire assembly. The high-melting-point glass frit layer is applied only at the peripheral seal region, so when heated, only the seal area reaches high temperature for hermetic bonding, while the rest of the assembly remains at lower temperature, reducing energy consumption and preventing thermal damage to components
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
This approach enables the production of VIG units with improved thermal integrity, reduced thermal conductivity, and compliance with environmental regulations by maintaining the temper strength of glass and avoiding high-temperature processing, while also providing a robust and durable hermetic seal.
Implementation Method 1
A method of forming a metal-inclusive peripheral edge seal using a metallic solder pre-form alloy that reacts to form inter-metallic compounds with pre-coated nickel and silver layers on the glass substrates
Implementation Method 2
A method of forming a metal-inclusive peripheral edge seal using a metallic solder pre-form alloy that, when reactively reflowed, wet and bond with metallic coatings pre-coated on the glass substrates' perimeters
Implementation Method 3
allowing for low-temperature processing (up to 250°C) and the use of lead-free alloys, such as SnAgCu, to create a hermetic seal without de-tempering the glass
Data Source
AI summary
Certain example embodiments relate to vacuum insulating glass units having edge seals formed in connection with solder alloys that, when reactively reflowed, wet metallic coatings pre-coated on the glass substrates' perimeters, and/or associated methods. The alloys may be based on materials that form seals at temperatures that will not de-temper glass and/or decompose a laminate, and/or remain hermetic and lack porous structures in their bulks. Example alloys may be based on inter-metallics of Sn and one or more materials selected from post-transition metals or metalloids; Zintl anions (e.g., In, Bi, etc.) from Group 13, 14, 15, or 16; and transition metals (e.g., Cu, Ag, Ni, etc.); and excludes Pb. Thin film coatings in certain example embodiments work with the solder material to form robust and durable hermetic interfaces. Because low temperatures are used, certain example embodiments can use compliant and visco-elastic spacer technology based on lamellar structures and/or the like.