Transparent Laser Weld Seals for Hermetic Glass Bonding
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Solution Overview
Problem
Existing methods for sealing glass substrates, such as frit-based sealants and conventional laser welding, often result in opaque, low-quality hermetic seals that are not optically clear, which is detrimental for applications requiring light transmission and transparency.
Innovation Solution
A laser sealing process using an interfacial thin film with absorptive properties, such as low melting glass (LMG), ultraviolet absorbing (UVA), or infrared absorbing (IRA) films, to initiate sealing between glass sheets, achieving transparent and hermetic bonds with localized sealing temperatures suitable for diffusion welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frit-based sealants are used for sealing glass substrates, then hermetic sealing is achieved, but the seal becomes opaque and loses optical clarity
Solution Approach 1:
The patent removes the organic binder and solvent components from the sealing paste, leaving only inorganic glass frit particles that can be sintered to form a hermetic seal. This extraction of organic components eliminates the source of opacity while maintaining sealing functionality through the inorganic glass matrix formation.
Solution Approach 2:
The patent changes the chemical composition parameters of the sealing material by using specific glass frit compositions with controlled particle sizes and chemical makeup. By adjusting these parameters, the seal achieves both hermeticity through glass matrix formation and optical clarity by eliminating organic contaminants and using transparent inorganic materials.
2Productivity
If conventional laser welding is used to seal glass substrates, then sealing speed is improved, but the seal quality becomes poor and opacity increases
Solution Approach 1:
The patent applies a thin film coating to the glass substrate surfaces before laser welding. This preliminary action creates a controlled absorption layer that enables efficient laser energy coupling, allowing for faster welding speeds while maintaining precise control over the weld zone and avoiding excessive melting that would cause opacity and poor seal quality.
Solution Approach 2:
The patent optimizes laser welding parameters including power density, pulse duration, and scanning speed to achieve transparent seals. By carefully controlling these parameters, the process maintains precise thermal control that prevents excessive melting and maintains optical clarity while achieving high sealing speeds.
3Reliability
If high temperature processing is used for frit sealing, then hermetic seal formation is achieved, but temperature-sensitive substrates are damaged
Solution Approach 1:
The patent segments the heating process into localized zones using focused laser energy. Instead of uniform high-temperature heating across the entire substrate, the laser concentrates energy only at the sealing line where glass frit needs to melt, allowing the rest of the substrate to remain at lower temperatures and avoid thermal damage to temperature-sensitive components.
Solution Approach 2:
The patent replaces conventional thermal field heating with a focused laser beam for localized heating. This substitution allows precise spatial control of thermal energy, enabling hermetic seal formation at the sealing interface while maintaining low temperatures in the bulk substrate, thus protecting temperature-sensitive materials.
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 process enables the formation of strong, transparent, and hermetic seals with efficient welding speeds, maintaining the optical clarity of the sealed region and accommodating substrates with different thermal expansion coefficients, thus addressing the limitations of existing sealing methods.
Implementation Method 1
bonding the workpiece between the first and second substrates by locally heating the film with laser radiation having a predetermined wavelength
Implementation Method 2
an inorganic film formed over a surface of a first substrate... bonding the workpiece between the first and second substrates by locally heating the film with laser radiation
Data Source
AI summary
Disclosed herein are sealed devices comprising a first substrate, a second substrate, an inorganic film between the first and second substrates, and at least one weld region comprising a bond between the first and second substrates. The weld region can comprise a chemical composition different from that of the inorganic film and the first or second substrates. The sealed devices may further comprise a stress region encompassing at least the weld region, in which a portion of the device is under a greater stress than the remaining portion of the device. Also disclosed herein are display and electronic components comprising such sealed devices.