Protective Tape for Foldable Display Modules
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Solution Overview
Problem
Flexible display devices face issues with protective tapes deforming or being damaged due to repeated stress at folding or bending portions, and existing solutions fail to maintain high adhesion force and durability while being removable without leaving residues.
Innovation Solution
A protective tape with a base film and an adhesive layer having a storage modulus of less than 0.3 MPa at -20°C and a creep value of 50% or greater at 60°C, ensuring high adhesion and durability, and designed to detach easily without residue, with initial adhesion force of 200 gf/in or greater and reduced adhesion force at higher temperatures for easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective tape is made with strong adhesion to maintain durability during repeated folding, then the adhesion force is improved, but the tape becomes difficult to remove and may leave residues
Solution Approach 1:
The adhesive layer's physical and chemical parameters are specifically optimized to achieve temperature-dependent adhesion behavior. The storage modulus is controlled to be less than 0.3 MPa at -20°C and the creep value is controlled to be 50% or greater at 60°C, creating a material that maintains strong adhesion during normal use and folding but allows easy removal when heated to 60°C or higher
Solution Approach 2:
The adhesive layer exhibits dynamic mechanical properties that change with temperature. At low temperatures (e.g., -20°C), the adhesive maintains high elasticity and adhesion strength to withstand repeated folding stresses. When heated to removal temperature (60°C or higher), the adhesive's creep value increases significantly, enabling easy detachment without residues
2Strength
If the protective tape is made rigid to maintain structural integrity, then the strength is improved, but the tape deforms or damages when repeatedly folded or bent
Solution Approach 1:
The protective tape is constructed as a thin film structure with specific flexibility characteristics. The base film and adhesive layer are designed with appropriate thickness and material properties to provide sufficient strength while maintaining the flexibility needed to withstand repeated folding and bending without deformation or damage
Solution Approach 2:
The protective tape employs a composite structure consisting of a base film and an adhesive layer with specifically controlled mechanical properties. The base film provides structural support while the adhesive layer with storage modulus <0.3 MPa at -20°C and creep value ≥50% at 60°C provides flexibility and stress absorption during folding operations
3Reliability
If the adhesive layer is made with high storage modulus to maintain adhesion at low temperature, then the adhesion force is improved, but the creep value decreases and the tape becomes difficult to remove
Solution Approach 1:
The adhesive layer's viscoelastic parameters are precisely controlled to achieve the desired dual behavior. The storage modulus is maintained below 0.3 MPa at -20°C to ensure flexibility and adhesion during cold conditions and folding, while the creep value is maintained at 50% or greater at 60°C to enable easy removal when heated
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 maintains high adhesion and durability during repeated folding and bending, ensuring the protective tape can be easily detached without leaving residues, improving the reliability and convenience of flexible display devices.
Implementation Method 1
the adhesive layer has a storage modulus of less than about 0.3 megapascal (MPa) at about −20° C. and a creep value of about 50% or greater when a shear stress of about 2000 pascal (Pa) is maintained for about 10 minutes at about 60° C.
Implementation Method 2
a creep value of about 50% or greater when a shear stress of about 2000 pascal (Pa) is maintained for about 10 minutes at about 60° C.
Data Source
AI summary
A display device includes a display module foldable along a folding axis, and a protective tape including a base film and an adhesive layer, wherein the adhesive layer has a storage modulus of less than about 0.3 MPa at about −20° C. and a creep value of about 100% or greater when a shear stress of about 2000 Pa is maintained for about 10 minutes at about 60° C.