Flexible Electronic Device Neutral-Axis Structure for Repeated Bending
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Solution Overview
Problem
Existing electronic devices face challenges in enhancing bend strength and repeated bending capability, leading to potential damage and failure due to stress on circuit layers during bending.
Innovation Solution
A flexible electronic device design comprising specific layers with varying Young's moduli and thicknesses, positioning the circuit layer at the neutral axis to minimize stress, including support layers and adhesive layers with specific material properties and thickness ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit layer is positioned in a conventional structure during bending, then the device can maintain basic structural integrity, but stress concentrates on the circuit layer causing potential damage and reducing repeated bending capability
Solution Approach 1:
The patent applies local quality by creating a neutral axis layer with specific material properties (Young's modulus between 0.01-10 GPa) positioned at the circuit layer's location. This local structural modification redistributes stress during bending, protecting the circuit layer from concentrated stress while maintaining overall device flexibility and bending capability.
Solution Approach 2:
The patent employs composite materials by combining the flexible substrate with a neutral axis layer having distinct material properties (lower Young's modulus than the substrate but higher than the adhesive layer). This composite structure enables stress redistribution during bending, enhancing both bend strength and repeated bending capability simultaneously.
2Strength
If support layers with high Young's modulus are used to enhance bend strength, then the structure becomes more rigid, but the flexibility and flexibility-substrate bonding are compromised
Solution Approach 1:
The patent applies parameter changes by carefully selecting the Young's modulus of the neutral axis layer to be between 0.01-10 GPa, which is lower than the flexible substrate's Young's modulus. This parameter optimization allows the support layer to provide structural support during bending while maintaining overall device flexibility and ensuring proper bonding with the flexible substrate.
Solution Approach 2:
The patent uses composite materials with specific Young's modulus relationships: the neutral axis layer has a lower Young's modulus than the flexible substrate but higher than the adhesive layer. This composite structure achieves a balance between rigidity for bend strength and flexibility for adaptability, resolving the contradiction between these two properties.
3Strength
If adhesive layers with high thickness are used to improve bonding, then the bonding strength increases, but the overall device thickness and weight increase
Solution Approach 1:
The patent applies parameter changes by optimizing the adhesive layer thickness to be between 1-100 micrometers and selecting materials with appropriate Young's modulus (0.001-0.1 GPa). This optimization achieves sufficient bonding strength between layers while minimizing the increase in overall device thickness and weight.
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 design significantly reduces stress on the circuit layer, enhancing bend strength and repeated bending capability, thereby minimizing damage and ensuring normal operation.
Implementation Method 1
A Young's modulus of the first support layer is greater than a Young's modulus of the first adhesive layer, and a Young's modulus of the second support layer is greater than a Young's modulus of the second adhesive layer
Implementation Method 2
positioning the circuit layer at the neutral axis to minimize stress
Data Source
AI summary
A flexible electronic device includes a first flexible substrate, a circuit layer disposed on a first adhesive layer, a first support layer, a second support layer and a second adhesive layer. The circuit layer includes a driving circuit and electronic components electrically connected to the driving circuit. The first adhesive layer is disposed between the first flexible substrate and the first support layer. The second adhesive layer is disposed between the second support layer and the circuit layer. A Young's modulus of the first support layer is greater than that of the first adhesive layer, and a Young's modulus of the second support layer is greater than that of the second adhesive layer. A thickness of the first support layer is less than that of the first adhesive layer, and a thickness of the second support layer is less than that of the second support layer.