Two-Stage Hermetic Seals for Evacuated Glazing Reliability
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Solution Overview
Problem
Existing evacuated glazing assemblies face failure due to differential pane movement, leading to cracking and seal failure, primarily through microleakage paths, flaws in the metallic bridge element, and misalignment of weld segments, necessitating a more reliable and cost-efficient hermetic seal configuration.
Innovation Solution
A two-stage hermetic seal element is implemented, comprising a first stage seal formed by a cold-welded bond between a metallic bridge element and a substrate, and a second stage seal formed by a sealing material in contact with the first stage seal, providing enhanced hermeticity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-stage hermetic seal using a metallic bridge element is used, then the manufacturing process is simpler and cost-efficient, but the seal reliability is insufficient due to microleakage paths, flaws, and misalignment
Solution Approach 1:
The hermetic seal is divided into two distinct stages: a first stage seal formed by cold-welding the metallic bridge element to the substrate, and a second stage seal formed by heating the sealing material. This segmentation allows each stage to perform its specific function optimally, with the first stage providing initial hermetic sealing and the second stage providing enhanced sealing reliability through thermal bonding, thereby resolving the contradiction between seal reliability and structural complexity.
Solution Approach 2:
The first stage seal is formed as a preliminary hermetic barrier before the second stage seal is applied. This preliminary action creates a baseline level of hermeticity that protects the interior space, and the subsequent second stage seal further enhances this protection. The preliminary first stage seal allows the system to achieve basic hermeticity with simpler processes while the second stage provides additional reliability.
2Reliability
If tightly-controlled manufacturing processes are used to minimize failure mechanisms, then seal reliability improves, but manufacturing cost and complexity increase
Solution Approach 1:
The sealing process utilizes parameter changes by transitioning from a cold-welding process (first stage) to a thermal heating process (second stage). This parameter change allows the sealing material to undergo phase transitions or property changes that enhance bonding and hermeticity. The thermal heating in the second stage activates the sealing material's adhesive properties, creating a more reliable seal without requiring extremely tight manufacturing tolerances throughout the entire process.
Solution Approach 2:
The seal element combines different materials with complementary properties: a metallic bridge element for structural integrity and initial bonding, and a separate sealing material that responds to thermal heating. This composite approach allows each material to be optimized for its specific function, with the metallic component providing mechanical strength and the sealing material providing enhanced hermetic bonding when heated, thereby achieving high reliability without requiring the entire manufacturing process to maintain extremely tight controls.
3Duration of action of stationary object
If the seal element is exposed to the environment, then manufacturing and installation is simpler, but the seal degrades faster due to environmental exposure
Solution Approach 1:
The first stage seal acts as a preliminary protective barrier that cushions the interior space from environmental exposure before the second stage seal is fully established. This prior cushioning provides initial protection against contaminants and moisture, and the subsequent second stage seal enhances this protection. The two-stage configuration creates redundant protection, ensuring that if one stage degrades, the other maintains hermeticity, thereby extending the seal's service life without requiring overly complex single-stage configurations.
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 two-stage seal element enhances hermeticity and structural integrity, reducing the likelihood of seal failure and extending the useful life of evacuated glazing assemblies by maintaining hermeticity even when the first stage seal degrades, while allowing the use of organic sealing materials and minimizing exposure to the environment.
Implementation Method 1
bonding a metallic bridge element to at least one of the substrates by cold welding to form a first stage seal
Implementation Method 2
heating the sealing material to form a second hermetic sealing stage
Data Source
AI summary
An evacuated glazing assembly has first and second spaced-apart, non-metal substrates connected to each other by a seal element to form an evacuable interior space therebetween. The seal element is formed by bonding a metallic bridge element to at least one of the substrates by cold welding to form a first stage seal and forming a second stage seal at least partially in contact with the first stage seal. The seal element is configured to hermetically isolate the interior space from the surrounding environment, and both the first stage seal and the second stage seal contribute to the hermeticity of the seal element.