Adhesive Layering for Flexible Display Stress Management
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Solution Overview
Problem
Flexible electronic apparatuses face reliability issues due to stress caused by bending or folding, as existing technologies fail to effectively manage stress distribution and prevent damage to components like display and window members.
Innovation Solution
The use of a layered structure with specific adhesive members having distinct moduli and stress relaxation properties, where the first adhesive member has a smaller radius of curvature and higher modulus than the second, and both are made of materials like silicon-based, urethane-based, or acrylic-based polymers, to decouple stress and reduce strain across components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single adhesive member is used to bond layers in a flexible electronic apparatus, then the structure is simple, but stress concentration occurs during bending causing reliability issues
Solution Approach 1:
The adhesive system is segmented into multiple adhesive members (first adhesive member and second adhesive member) with different moduli positioned between various layers (window member, polarizing film, display panel). This segmentation allows each adhesive member to manage stress differently during bending, preventing stress concentration and improving reliability of the flexible electronic apparatus.
2Reliability
If adhesive members with different moduli are used to manage stress distribution, then stress relaxation is improved, but manufacturing precision requirements increase due to specific modulus matching
Solution Approach 1:
The patent specifies precise parameter ranges for the adhesive members, including modulus values (first modulus and second modulus with specific relationships), stress relaxation ratios (70% or less), and thickness ratios. By controlling these parameters within defined ranges, the system achieves optimal stress relaxation during bending while maintaining manufacturability through clear specification guidelines.
3Reliability
If the radius of curvature of the first adhesive member is smaller than the second, then stress distribution during bending is optimized, but the bending radius constraint reduces design flexibility
Solution Approach 1:
Different adhesive members are assigned different local properties: the first adhesive member (between window member and polarizing film) has a smaller radius of curvature and higher modulus, while the second adhesive member (between polarizing film and display panel) has a larger radius of curvature and lower modulus. This local differentiation optimizes stress distribution at each interface during bending, with each adhesive member tailored to its specific structural position and stress 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
This configuration improves the reliability of flexible electronic apparatuses by reducing stress concentrations and preventing damage during bending, maintaining component integrity and functionality.
Implementation Method 1
wherein a stress relaxation of the first adhesive member is about 70% or less
Implementation Method 2
a first adhesive member having a first modulus, a second adhesive member having a second modulus
Data Source
AI summary
An electronic apparatus includes a first adhesive member having a first modulus, a second adhesive member having a second modulus, and a flexible member between, and contacting, the first adhesive member and the second adhesive member, wherein a stress relaxation of the first adhesive member is about 70% or less, and wherein an absolute value of a difference between the first modulus and the second modulus is about 0.01 MPa or less.