Vacuum Insulated Glass Edge Seal Height Control
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Solution Overview
Problem
Vacuum insulated glass (VIG) units often experience breakage during the pump-down process due to variations in edge seal height, which cause stress on the glass substrates, leading to bending or flexing and subsequent breakage.
Innovation Solution
Implementing a method to control the initial dispensed height of the seal material and the flow of the seal material during firing, along with ensuring temperature uniformity, to reduce final edge seal height variations to less than 0.10 mm, thereby minimizing stress on the glass substrates during the pump-down process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If seal material is applied manually or with conventional methods, then the application process is simple, but the edge seal height varies significantly causing glass breakage during pump-down
Solution Approach 1:
The patent applies preliminary action by depositing the seal material to a controlled initial height before firing, ensuring that the seal material is pre-positioned with precise height control. This preliminary height control prevents excessive variation during the firing process and subsequent pump-down operation, thereby reducing glass breakage while maintaining a manageable application process through automated deposition equipment.
2Manufacturing precision
If the seal material is allowed to flow freely during firing, then the sealing process is simpler, but the edge seal height variation increases causing stress on glass substrates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the firing process parameters including temperature profile, heating rate, and atmosphere composition. By optimizing these parameters, the seal material flows sufficiently to form a hermetic seal while limiting excessive flow that would cause height variation. This controlled parameter approach ensures uniform edge seal height and reduces glass substrate stress during pump-down.
3Manufacturing precision
If temperature uniformity is not controlled during firing, then the firing process is faster and simpler, but the seal material flows unevenly causing height variation and glass breakage
Solution Approach 1:
The patent applies equipotentiality by creating a uniform temperature distribution across the glass assembly during firing. The firing process is designed to maintain consistent temperature conditions that ensure uniform seal material flow characteristics throughout the entire assembly. This uniform thermal environment prevents localized excessive flow or insufficient sealing, achieving consistent edge seal height and reducing glass breakage risk.
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
Significantly reduces the instances of glass breakage during the pump-down process by maintaining consistent edge seal height, ensuring a hermetic seal and reducing the likelihood of glass bending or flexing.
Implementation Method 1
The entire assembly including the glass substrates 2, 3, the spacers/pillars 5 and the seal material (e.g., glass frit in solution or paste), is then heated to a temperature of at least about 500° C., at which point the glass frit melts, wets the surfaces of the glass substrates 2, 3, and ultimately forms a hermetic peripheral/edge seal 4.
Implementation Method 2
After evacuation of the cavity 6, a portion (e.g., the tip) of the tube 8 is melted to seal the vacuum in low pressure cavity/space 6.
Data Source
AI summary
A vacuum insulated glass (VIG) window assembly and method for making same is provided in which a variation in the final edge seal height is preferably 0.20 mm or less, more preferably about 0.15 mm or less. Controlling final edge seal height variations substantially reduces breakage of the glass substrates of the VIG window assembly during vacuum pump-down of the cavity between the glass substrates. Edge seal height variation may be controlled, for example, by controlling initial dispensing of green frit material, controlling temperature variations during firing, and/or controlling cycle times during firing.