Flexible Display Adhesive Modulus Control for Hot Folding Stress
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Solution Overview
Problem
Flexible display modules are prone to defects due to stress caused by folding under high temperatures, leading to reduced reliability and durability.
Innovation Solution
Incorporating an adhesive layer with a storage modulus of 0.02-0.045 MPa and creep characteristics of 10-30% at 60°C, and a thickness of 25-75 micrometers, to prevent peeling and cracking of functional layers during folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display module is folded under high temperature, then the flexibility and portability are improved, but stress-induced defects and reduced reliability occur
Solution Approach 1:
The patent applies parameter changes by carefully controlling the storage modulus and creep characteristics of the adhesive layer at elevated temperatures (60°C). The storage modulus is maintained within 0.02-0.045 MPa and creep characteristics within 10-30%, allowing the adhesive to accommodate thermal expansion and folding stresses without failing, thus maintaining reliability while enabling flexibility
Solution Approach 2:
The patent uses a composite structure consisting of the display panel, functional layers, and adhesive layer with specifically engineered properties. The adhesive layer acts as a buffer zone that absorbs stress during folding, preventing defect propagation between the rigid display components and enabling reliable flexible operation
2Strength
If the adhesive layer has higher storage modulus, then the bonding strength is improved, but stress-induced cracking increases under folding conditions
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the storage modulus parameter within a narrow range (0.02-0.045 MPa at 60°C). This optimized parameter range provides sufficient bonding strength to hold functional layers while being low enough to allow stress relaxation during folding, preventing cracking that would occur with higher modulus adhesives
Solution Approach 2:
The adhesive layer exhibits dynamic mechanical properties that adapt to folding conditions. The controlled creep characteristics (10-30%) allow the adhesive to deform progressively under stress, dissipating energy and preventing sudden crack formation while maintaining adequate bonding strength
3Object-affected harmful factors
If the adhesive layer has higher creep characteristics, then the stress relaxation is improved, but the bonding stability deteriorates
Solution Approach 1:
The patent balances stress relaxation and bonding stability by controlling creep characteristics within 10-30% at 60°C. This range is sufficiently high to allow stress relaxation during folding cycles, preventing defect accumulation, while remaining low enough to maintain bonding stability and prevent functional layer delamination
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 adhesive layer enhances the reliability and durability of the display module by preventing peeling and cracking of components, ensuring long-term functionality.
Implementation Method 1
The adhesive layer has a storage modulus equal to or greater than about 0.02 MPa and equal to or smaller than about 0.045 MPa at a temperature of about 60° C. and has creep characteristics equal to or greater than about 10% and equal to or smaller than about 30%
Data Source
AI summary
A display module includes a display panel, a plurality of functional layers disposed on the display panel, and an adhesive layer disposed between the plurality of functional layers or between one of the plurality of functional layers and the display panel. The adhesive layer has a storage modulus equal to or greater than about 0.02 megapascal (MPa) and equal to or smaller than about 0.045 MPa at a temperature of about 60 degrees Celsius (° C.) and has creep characteristics equal to or greater than about 10 percent (%) and equal to or smaller than about 30%.