Ozone Cleaning for Vacuum Insulated Glass Cavities
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Solution Overview
Problem
Vacuum insulated glass (VIG) units with lower temperature seal compositions, such as vanadium-based and VBZ type seals, face challenges in removing residual hydrocarbons and polymers due to insufficient burn-off at lower thermal profiles, leading to contamination and degradation of vacuum levels and coatings over time.
Innovation Solution
A cleaning process using an ozone (O3) and oxygen (O2) mixture is introduced into the VIG cavity during the initial pump-down process, oxidizing residual carbon compounds to make them more volatile and easily removable, with optional additional energy sources like RF plasma or UV lamps to enhance reaction rates, followed by sequential N2 purging and deep vacuum pull-down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lower temperature seal compositions (vanadium-based, VBZ type) are used, then the thermal profile is reduced and energy consumption decreases, but residual hydrocarbons and polymers are not sufficiently removed leading to vacuum degradation
Solution Approach 1:
The patent applies preliminary action by introducing ozone into the cavity before final vacuum sealing to pre-oxidize residual hydrocarbons and polymers. This preliminary oxidation converts the residues into more volatile compounds that can be removed during subsequent vacuum pumping, preventing future vacuum degradation without requiring high-temperature processing that would compromise the seal composition.
Solution Approach 2:
The patent changes the chemical state of residual contaminants by introducing ozone, which oxidizes hydrocarbons and polymers into more volatile compounds. This parameter change in the chemical composition and volatility of residues enables their removal at lower temperatures, resolving the contradiction between low thermal profile and effective contaminant removal.
2Object-generated harmful factors
If high-temperature processing is used to remove residual hydrocarbons, then contaminant removal is improved, but the seal composition and glass substrates may be damaged
Solution Approach 1:
The patent uses ozone, a strong oxidant, to accelerate the oxidation of residual hydrocarbons and polymers at lower temperatures. This accelerated oxidation by a strong oxidizing agent achieves effective contaminant removal without requiring high-temperature processing, thereby preserving the integrity of the seal composition and glass substrates.
Solution Approach 2:
The patent replaces the thermal-mechanical removal mechanism (high-temperature burn-off) with a chemical mechanism (ozone oxidation). This substitution allows contaminant removal through chemical transformation rather than thermal degradation, avoiding damage to the seal and substrates while effectively eliminating harmful residues.
3Manufacturing precision
If ozone is introduced into the cavity, then residual carbon compounds are oxidized and removed more effectively, but additional process steps and equipment are required
Solution Approach 1:
The patent uses ozone as an intermediary substance to facilitate contaminant removal. The ozone acts as a mediator that oxidizes residual hydrocarbons and polymers into volatile compounds, which are then removed by the existing vacuum pump system. This intermediary approach achieves high manufacturing precision in contaminant removal while utilizing relatively simple equipment that can be integrated into existing vacuum processing lines.
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 method effectively enhances the insulating value, extends the useful life of VIG units, and maintains the integrity of coatings by reducing residual contaminants to acceptable levels without high-temperature processing, ensuring a stable R-value and preventing vacuum degradation.
Implementation Method 1
oxidizing residual carbon compounds to make them more volatile and easily removable
Implementation Method 2
removing compounds created by reaction with the cleaning gas mixture
Data Source
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AI summary
A method and apparatus for cleaning a cavity of a vacuum insulated glass window assembly is provided in which a cleaning gas mixture of or including ozone is introduced into the cavity of the vacuum insulated glass assembly and allowed to react with residual materials, such as, for example, hydrocarbons and/or polymers. Reacted hydrocarbons and/or polymers are then removed from the vacuum cavity along with any residual cleaning gas mixture. The cleaning method is preferably performed at substantially ambient temperatures or at least temperatures below about 250°C. The ozone cleaning cycle may be repeated multiple times and followed by additional purges with other gases, such as for example nitrogen. Additional energy may be provided by heating, RF plasma; corona discharge, UV lamp, and/or the like.