Optical Panel Laminating Structure with Low-Adhesion Layers
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Solution Overview
Problem
Traditional edge lamination technologies with air gaps in display panels face issues such as reduced touch sensitivity, optical performance, and difficulties in rework and residual glue removal, leading to lower production yield and increased costs.
Innovation Solution
A laminating structure using a combination of first and second transparent low-adhesion adhesive layers and optical transparent sheets with no air gaps, employing materials like silicone resin, polyurethane adhesive, and organic or inorganic transparent sheets, which allows for full lamination without the need for expensive equipment and simplifies rework by reducing adhesive force and eliminating the need for solvents or blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acrylic adhesive with strong adhesion is used for full lamination, then laminating strength and optical performance are improved, but reworkability deteriorates and residual glue removal becomes difficult
Solution Approach 1:
The adhesive system is segmented into multiple functional layers: a first transparent low-adhesion adhesive layer for initial bonding and alignment, an optical clear adhesive layer for structural strength, and a second transparent low-adhesion adhesive layer for final sealing. This segmentation allows each layer to perform its specific function optimally while enabling easy rework by removing only the low-adhesion outer layers.
Solution Approach 2:
The adhesive strength parameter is varied across different layers of the laminating structure. The outer adhesive layers use materials with specifically controlled lower adhesion strength (e.g., silicone resin, polyurethane) compared to the central OCA layer, creating a gradient of bonding strength that facilitates reworkability while maintaining overall structural integrity.
2Reliability
If conventional full lamination with OCA is used, then optical performance and laminating strength are improved, but production yield deteriorates due to air bubbles and defects
Solution Approach 1:
The first transparent low-adhesion adhesive layer is applied to the protective cover lens or touch panel before the OCA layer, creating a preliminary bonding interface that holds components in position during assembly. This preliminary action allows for proper alignment and eliminates air pockets before the final OCA lamination, preventing defects that would reduce production yield.
Solution Approach 2:
The first and second transparent low-adhesion adhesive layers act as intermediary layers between the rigid OCA layer and the protective cover lens or touch panel. These intermediary layers provide a buffer that accommodates minor surface irregularities and prevents direct transmission of air bubbles from the OCA layer to the final optical interface, thereby improving production yield.
3Strength
If acrylic adhesive is used for full lamination, then adhesion strength is improved, but yellowing occurs over time deteriorating optical appearance
Solution Approach 1:
The laminating structure uses a composite adhesive system combining different material types: silicone resin or polyurethane for the outer low-adhesion layers (resistant to yellowing), and optical clear adhesive in the center for structural strength. This composite approach allows the outer layers to protect the inner OCA layer from UV exposure and environmental factors that cause yellowing, while maintaining overall adhesion strength.
4Loss of substance
If traditional edge lamination with air gap is used, then adhesive consumption is reduced, but touch sensitivity and optical performance deteriorate
Solution Approach 1:
Instead of complete edge-to-edge lamination, the adhesive is applied in partial coverage zones: the first and second transparent low-adhesion adhesive layers are applied only at the periphery or in specific zones where full coverage is not necessary for structural integrity. This partial action reduces adhesive consumption while maintaining sufficient bonding and preserving touch sensitivity by avoiding excessive adhesive in the active touch area.
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 solution enhances the reworkability and production yield of display panels by reducing adhesive force, minimizing residual glue, and preventing yellowing, while maintaining optical performance and improving touch accuracy without requiring expensive equipment.
Implementation Method 1
The first transparent low-adhesion adhesive layer is repeatedly removeable and directly attached to the protective cover lens or the touch panel. The second transparent low-adhesion adhesive layer is repeatedly removeable and directly attached to the display module.
Implementation Method 2
The first optical transparent sheet is stacked between the first transparent low-adhesion adhesive layer and the second transparent low-adhesion adhesive layer, an upper surface of the first optical transparent sheet and a lower surface of the first optical transparent sheet are directly attached to an optical clear adhesive (OCA) layer, and there is no air gap between both the OCA layers and the first transparent low-adhesion adhesive layer and the second transparent low-adhesion adhesive layer.
Data Source
AI summary
A laminating structure of an optical clear binder (OCB) of an optical panel is applied between a display protective cover lens and a display module, or between a touch panel and the display module. The laminating structure includes two transparent low-adhesion adhesive layers and a first optical transparent sheet. One of the transparent low-adhesion adhesive layers is repeatedly removeable and directly attached to the protective cover lens or the touch panel, the other one of the transparent low-adhesion adhesive layers is repeatedly removeable and directly attached to the display module. The first optical transparent sheet is stacked between both the transparent low-adhesion adhesive layers. An upper surface of the first optical transparent sheet and a lower surface of the first optical transparent sheet are directly attached to an optical clear adhesive (OCA) layer.