Lignin-Modified Polyimide Substrate for Laser Lift Off Protection
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Solution Overview
Problem
Polyimide substrates in flexible displays are prone to damaging liquid crystals during the Laser Lift Off process due to the lack of light screening, affecting display quality.
Innovation Solution
A polyimide substrate is prepared by dissolving lignin, polyimide, and a free radical polymerization initiator in an organic solvent, coated on a glass substrate, and reacted in a nitrogen gas atmosphere, shifting the maximum absorption peak from less than 280 nm to 380 nm to absorb light waves during the LLO process, thereby protecting the substrate and liquid crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional polyimide substrate is used during the Laser Lift Off process, then the substrate can be removed from the glass base, but the liquid crystals inside the display panel are damaged due to direct laser influence
Solution Approach 1:
The patent introduces an intermediary substance (lignin or its derivatives) incorporated into the polyimide substrate that acts as a mediator between the laser beam and the liquid crystals. This intermediary absorbs the harmful laser radiation (wavelengths ≤380 nm) and converts it to harmless forms, protecting the liquid crystals while allowing the LLO process to proceed
Solution Approach 2:
The patent converts the harmful laser radiation into a beneficial effect by using the absorbed energy to drive photo-polymerization reactions in the lignin-containing polyimide substrate. The laser energy that would otherwise damage the liquid crystals is instead utilized to enhance the crosslinking and mechanical properties of the substrate during the LLO process
2Object-affected harmful factors
If lignin is introduced into the polyimide structure to provide light absorption, then the maximum absorption peak redshifts to ≤380 nm providing screening protection, but the substrate must be manufactured with additional components
Solution Approach 1:
The patent creates a composite material by combining polyimide with lignin or its derivatives. This composite structure integrates the light-absorbing properties of lignin (which redshifts the absorption peak to ≤380 nm) with the structural integrity and thermal stability of polyimide, achieving both protection and manufacturability
Solution Approach 2:
The lignin component serves multiple functions simultaneously: it provides light absorption and screening protection, acts as a photo-initiator for polymerization, and enhances the mechanical properties of the substrate. This multi-functionality reduces the need for additional separate components, simplifying the overall system despite the added complexity of the composite structure
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 modified polyimide substrate effectively prevents damage from light waves during the LLO process, ensuring high display quality and maintaining excellent thermal stability and transparency.
Implementation Method 1
the polyimide substrate may absorb the lights with wavelengths ≤380 nm, thus it may be effectively prevented that the substrate and the liquid crystals inside the panel are damaged during the LLO process
Implementation Method 2
dissolving lignin, polyimide and a free radical polymerization initiator in an organic solvent; and coating the solution obtained after dissolution on a glass substrate, and obtaining a polyimide substrate by reacting in a nitrogen gas atmosphere
Data Source
AI summary
The present invention relates to the field of displays and discloses a polyimide substrate, which is manufactured by reacting lignin, polyimide and a free radical initiator. Because lignin contains various active groups, for example, hydroxyl, carboxyl and aryl, etc., when it is introduced into the polymer structure of polyimide, the maximum absorption peak of the polymer can be made to redshift from less than or equal to 280 nm to less than or equal to 380 nm, so that a certain absorption and screening action may be laid on the light wave during a subsequent Laser Lift Off process, and the substrate and the liquid crystal may be prevented from being damaged during a Laser Lift Off process of the glass base substrate, thereby guaranteeing the display quality of the flexible display.