Composite Panel Adhesive Stress Management
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Solution Overview
Problem
Existing display devices face flexibility issues and performance degradation due to compressive/tensile stresses when folding, leading to cracks and disconnections in touch sensor panels, particularly in foldable devices.
Innovation Solution
A composite panel design featuring a substrate-less touch sensor panel coupled with adhesive layers of specific modulus and thickness, integrating a window panel and functional layers to minimize stress, thereby preventing cracks and enhancing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional display device structure with window panel, touch sensor panel, decorative panel, and functional layers is used, then the device can achieve narrow bezel and basic functionality, but compressive/tensile stresses during folding cause cracks and disconnections in the touch sensor panel
Solution Approach 1:
The patent applies flexible thin film materials throughout the composite panel structure. The touch sensor panel uses flexible transparent substrates (PET, PC, COP), the window panel uses flexible transparent films, and the decorative panel uses flexible films with specific mechanical properties. These flexible thin films enable the entire assembly to bend and fold without generating excessive stress that would cause cracks or disconnections, thus maintaining reliability while achieving foldable device capability.
Solution Approach 2:
The patent creates a composite panel structure where multiple different materials are combined: flexible transparent substrates for the touch sensor panel, various adhesive layers with different moduli, flexible window panel films, decorative panels, and functional layers. This composite material approach allows optimization of each layer's mechanical properties to work together harmoniously during folding, preventing stress concentration that would otherwise damage individual components like the touch sensor panel.
2Adaptability or versatility
If multiple layers (window panel, touch sensor panel, decorative panel, functional layer) are stacked and coupled via adhesive layers, then the composite panel achieves structural completeness and functionality, but the cumulative compressive/tensile stress during folding deteriorates touch sensor panel performance
Solution Approach 1:
The patent introduces adhesive layers as intermediary elements between the window panel, touch sensor panel, decorative panel, and functional layers. These adhesive layers act as stress-absorbing mediators that decouple the mechanical stresses generated during folding from the touch sensor panel. By positioning the adhesive layers at the interfaces between components, they absorb and distribute compressive and tensile stresses, preventing direct stress transmission to the touch sensor panel and thereby reducing harmful effects.
Solution Approach 2:
The patent optimizes the mechanical parameters of the adhesive layers, specifically controlling their thickness (5-50 μm) and modulus (0.01-1 MPa). By adjusting these parameters, the adhesive layers can effectively absorb stress while maintaining proper bonding between components. This parameter optimization ensures that the cumulative stress from multiple stacked layers during folding does not exceed the tolerance of the touch sensor panel, thus protecting it from performance deterioration.
3Reliability
If the adhesive layer thickness and modulus are optimized to minimize stress, then the flexibility and reliability of the foldable device improve, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies optimized parameter ranges for the adhesive layers: thickness of 5-50 μm and modulus of 0.01-1 MPa. These ranges are carefully selected to balance stress absorption capability with manufacturing feasibility. The lower bound ensures sufficient stress absorption, while the upper bound maintains manufacturability. This parameter specification approach allows manufacturers to achieve reliable stress minimization without requiring extreme precision, thus resolving the contradiction between reliability improvement and manufacturing precision requirements.
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 solution effectively reduces compressive/tensile stress on touch sensor panels, preventing cracks and disconnections, while thinning the panel and simplifying the manufacturing process, thereby increasing flexibility and reducing manufacturing costs.
Implementation Method 1
a first adhesive layer, one surface of which is coupled to one surface of the touch sensor panel and the other surface of which is coupled to one surface of the window panel... the first adhesive layer or the second adhesive layer may have a thickness of 10 to 50 μm and a modulus of 0.02 to 1 MPa
Data Source
AI summary
A composite panel includes a substrate-less touch sensor panel and a first coupling member coupled to one surface of the touch sensor panel via a first adhesive layer.