VIG Edge Profiles for Hermetic Seal Integrity
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Solution Overview
Problem
Conventional vacuum insulated glass (VIG) units face challenges with high processing temperatures that compromise the temper strength of heat-strengthened or tempered glass and can affect low-E coatings, leading to undesirable stress and potential deformation or breakage, while the brittle ceramic or solder glass edge seals are prone to cracking and inadequate sealing, especially in designs with equally sized substrates.
Innovation Solution
The introduction of glass edge profiles with step features that provide additional surface area for frit attachment, improving edge seal quality and retention, and allowing for lower temperature processing to maintain temper strength and reduce stress on glass substrates, along with specific edge profiles such as 'flat with step', 'beveled with step', and 'reverse beveled with step' designs that facilitate easier frit application and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high processing temperatures (approximately 500°C) are used to form the edge seal, then the frit melts and forms hermetic peripheral seal, but the temper strength of heat-strengthened or tempered glass substrates is compromised and low-E coatings are adversely affected
Solution Approach 1:
The patent introduces a step feature in the glass edge profile that changes the geometric parameters of the sealing surface. This step provides additional surface area for frit attachment, allowing the frit to form a strong bond at lower temperatures. The step feature effectively modifies the sealing interface geometry to enable reliable sealing without requiring high temperatures that would compromise the temper strength of the glass substrates.
2Reliability
If high processing temperatures are used for edge seal formation, then hermetic sealing is achieved, but the glass substrates experience stress and potential deformation or breakage
Solution Approach 1:
The step feature adds a dimensional element to the glass edge profile, creating a multi-level sealing surface. This additional dimension provides more surface area for frit attachment and creates a mechanical interlock that enhances sealing efficiency. The step effectively transforms a two-dimensional sealing interface into a three-dimensional structure, improving sealing reliability without requiring increased thermal energy that would cause stress.
3Ease of manufacture
If conventional flat glass edges are used, then manufacturing is simple, but the frit has insufficient surface area to attach to, resulting in poor edge seal quality
Solution Approach 1:
The glass edge is segmented into multiple levels by introducing the step feature. This segmentation divides the sealing surface into distinct zones: an upper level for frit application and a lower level that provides additional attachment area. The segmentation creates a multi-zone sealing interface that significantly increases the effective surface area for frit bonding, thereby improving edge seal quality while maintaining manufacturing feasibility through standard glass processing techniques.
4Volume of moving object
If small capillary VIG unit designs are used, then the unit size is reduced, but frit retention becomes inadequate leading to poor sealing
Solution Approach 1:
The step feature creates a nested structure where the lower level of the step is positioned within the capillary space. This nested configuration allows the frit to be retained in the step recess, effectively using the step as a containment feature. The nested structure prevents frit from migrating out of the sealing zone, thereby improving frit retention in small capillary designs where space is limited.
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
These edge profiles enhance the quality and durability of the edge seal, maintaining more of the glass substrates' original temper strength and reducing the likelihood of deformation or breakage, while improving frit retention and sealing efficiency, especially in small capillary designs and applications with lead-free frits.
Implementation Method 1
The entire assembly including sheets 2, 3, the spacers, and the seal material is then heated to a temperature of approximately 500° C., at which point the glass frit melts, wets the surfaces of the glass sheets 2, 3, and ultimately forms hermetic peripheral or edge seal 4
Implementation Method 2
the glass frit melts, wets the surfaces of the glass sheets 2, 3, and ultimately forms hermetic peripheral or edge seal 4
Implementation Method 3
Better frit retention, in turn, may be particularly advantageous with small capillary VIG unit designs
Data Source
AI summary
Certain example embodiments of this invention relate to vacuum insulated glass (VIG) units. The VIG unit may comprise first and second substrates with inner and outer substantially planar surfaces. For either or both of the first and second substrates, when considered along a side cross-section, a portion of the inner planar surface is removed proximate to an outer edge of the glass substrate so as to form a shoulder portion. An inner surface of the shoulder portion is angled (a negative number of degrees, zero degrees, or a positive number of degrees) relative to the inner and outer planar surfaces. The shoulder portion at its smallest height is at least about 50% of the glass substrate at its largest height. A side portion of the step proximate the edge also may be angled, e.g., so that it is or is not perpendicular to the planar surfaces.