UV Absorber Adhesive for Clean Laser Cutting of Foldable Displays
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Solution Overview
Problem
The challenge in manufacturing foldable display devices is the residue of adhesive members remaining on the cut surfaces during the laser cutting process, which hinders subsequent processes and affects the reliability of the display device.
Innovation Solution
Incorporating an ultraviolet light absorber in the adhesive members, specifically benzotriazole, benzophenone, or similar compounds, to reduce transmittance in the UV laser range, allowing precise cutting while preventing residue formation, and using multiple adhesive layers with varying surface roughness and thickness to enhance alignment and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser cutting is used to cut the adhesive member during manufacturing, then cutting speed and efficiency are improved, but adhesive residue remains on the cut surface causing process failures
Solution Approach 1:
The patent changes the optical parameters of the adhesive member by incorporating UV absorbers (benzotriazole, benzophenone, salicylic acid, or their derivatives) at concentrations of 0.1-10 wt%, which modifies the adhesive's light absorption characteristics in the UV range (300-400nm). This allows the adhesive to selectively absorb laser energy and achieve clean cutting without residue formation, resolving the contradiction between cutting efficiency and process reliability.
Solution Approach 2:
The patent creates a composite adhesive material by combining the base adhesive polymer with specific UV-absorbing compounds. This composite structure enables the adhesive to maintain its bonding functionality while gaining laser absorption capabilities, allowing clean laser cutting without compromising adhesive performance. The composite approach solves both the cutting quality issue and maintains manufacturing productivity.
2Illumination intensity
If the adhesive member has high UV transmittance to allow visible light passage, then display luminance is improved, but laser cutting produces residue on the cut surface
Solution Approach 1:
The patent applies local quality by making the adhesive's optical properties wavelength-dependent. The UV absorbers are specifically designed to absorb only in the UV range (300-400nm) where the laser operates, while maintaining high transmittance in the visible range (400-800nm) for display luminance. This selective absorption approach resolves the contradiction between cut surface quality and display performance.
Solution Approach 2:
The patent modifies the adhesive's spectral transmission parameters by adding UV absorbers that create a selective transmission window. The adhesive maintains >80% transmittance in the visible range for good luminance while having low transmittance (<20%) in the UV laser range for clean cutting. This parameter optimization simultaneously achieves both manufacturing precision and display quality.
3Strength
If the adhesive member thickness is increased to ensure adequate bonding strength, then adhesive force is improved, but laser cutting becomes less precise and may leave residue
Solution Approach 1:
The patent changes the optical absorption parameters of the adhesive by incorporating UV absorbers, which enables precise laser cutting even through thicker adhesive layers. The UV absorbers ensure complete laser energy absorption within the adhesive thickness, preventing residue formation regardless of whether the adhesive is 10μm or 50μm thick. This allows maintaining adequate bonding strength while preserving cut precision.
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 approach ensures smooth post-processing operations and improves the reliability of the display device by preventing adhesive residue on cut surfaces, ensuring effective folding and maintaining adhesive force while allowing high transmittance in visible light ranges for improved luminance.
Implementation Method 1
an adhesive member disposed between a polarizing member and a window member and including an ultraviolet light absorber. As the adhesive member includes the ultraviolet light absorber, transmittance of an ultraviolet laser irradiated to the adhesive member is lowered during the cutting process using the ultraviolet laser
Data Source
AI summary
A display device includes a display panel including a first surface and a second surface opposite to the first surface, a polarizing member disposed on the first surface of the display panel, a window member disposed on the polarizing member, and a first adhesive member disposed between the window member and the polarizing member and including an ultraviolet light absorber. A side surface of the display panel, a side surface of the polarizing member, and a side surface of the first adhesive member have a first surface roughness, an upper surface of the first adhesive member has a second surface roughness less than the first surface roughness, and the side surface of the display panel, the side surface of the polarizing member, and the side surface of the first adhesive member are aligned at a boundary.