Adhesive Dot Pattern for Bubble-Free Display Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for bonding a transparent cover plate to a flat display face challenges such as air bubbles, warping, and uneven adhesive distribution, particularly when using optical adhesives, which can lead to reduced impact resistance and visibility issues due to Newton rings and conspicuous bright spots, especially in thinner models and warped components.
Innovation Solution
A method involving the application of a UV-curable or visible light-curable adhesive in multiple spots around the corners and center, followed by linear application to connect these spots, allowing the adhesive to drip and fill gaps uniformly without air bubbles, and curing with light from the front and sides to ensure even bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an optical adhesive sheet is used to bond the touch panel and flat display together in full-surface contact, then the bonding strength is improved, but air bubbles form and cause visible defects
Solution Approach 1:
The adhesive application is segmented into multiple spots (first adhesive spots) distributed across the bonding surface, rather than applying adhesive uniformly across the entire surface. This segmentation allows air to escape between spots while maintaining bonding strength, preventing air bubble formation in the final bonded structure.
Solution Approach 2:
The adhesive is applied in spots before the actual bonding process, allowing the adhesive to spread and fill gaps uniformly when pressure is applied, while the spotted pattern prevents air entrapment. This preliminary spotted application resolves the air bubble issue before bonding occurs.
2Length of moving object
If the gap between the transparent cover plate and display panel is thinned to 0.1 mm or less, then the device thickness is reduced, but impact resistance decreases and Newton rings occur
Solution Approach 1:
The adhesive formulation parameters are changed to achieve low viscosity and appropriate curing characteristics, enabling the adhesive to effectively fill very thin gaps (0.1 mm or less) while maintaining bonding strength and impact resistance. The refractive index is also optimized to match the surrounding materials, eliminating Newton rings in the thin gap structure.
3Device complexity
If adhesive is dripped only on the central part to simplify application, then the process complexity is reduced, but the corners remain unfilled causing uneven adhesive distribution
Solution Approach 1:
The adhesive application uses local quality by placing adhesive spots at specific locations (corners and center) rather than uniform distribution. The corner spots ensure adhesive reaches the corners, while the center spot provides additional filling, achieving uniform distribution without complex application processes.
4Manufacturing precision
If multiple adhesive spots are applied to fill corner gaps, then the adhesive distribution is improved, but air bubbles form between the adhesive spots
Solution Approach 1:
The adhesive is applied as segmented spots rather than continuous coverage, which counterintuitively prevents air bubble formation. The spots are strategically positioned to allow air to escape through the gaps between spots during bonding, while the adhesive spreads to fill the gaps uniformly, achieving both corner coverage and air bubble prevention.
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 achieves air bubble-free, uniformly thick adhesive layers, reducing the gap between the cover plate and display to 20-30 µm, enhancing impact resistance and visual clarity by eliminating conspicuous bright spots and ensuring even curing without warping or detachment.
Implementation Method 1
a UV-curable or visible light-curable adhesive is applied
Data Source
Figure 1~4
Figure 5~9
Figure 10~12
AI summary
Provided is a method of bonding a transparent plate or a touch panel to a flat display without allowing air bubbles to form. A fixed amount of liquid adhesive is applied in dots to a bonding surface around corners and at the center. More adhesive is applied to connect the dots of applied adhesive with lines. The bonding surface is then reversed, causing the adhesive to drip, and the dripping adhesive is brought into contact with an opposite bonding surface to fill a gap between the bonding surfaces with the adhesive. The adhesive is cured by irradiation with light incident from a transparent plate side. In short, after dots of adhesive are brought into contact with the opposite bonding surface and the adhesive flows into a pattern that does not let in air bubbles, the gap between the bonding surfaces is filled with the adhesive.