Variable Adhesive Layer for Display Rework via Phase Transition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional reworkable adhesives for display devices suffer from adhesion deterioration at elevated temperatures, leading to reduced reliability and increased risk of component damage during reworking processes, and struggle to maintain adhesion at temperatures where it is needed.
Innovation Solution
A variable adhesive film comprising a block copolymer and a plasticizer mixture with a low critical solution temperature of 60° C. to 80° C., allowing for controlled adhesion by phase separation, providing high adhesion at lower temperatures and rapid decrease at reworking temperatures, thus enabling easy reworking without damaging components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional reworkable adhesives are used to enable easy separation at high temperature, then reworking becomes easier, but adhesion reliability deteriorates at temperatures below reworking temperature
Solution Approach 1:
The adhesive composition changes its adhesive properties by changing temperature parameters. At normal temperatures (below LCST), the adhesive maintains strong adhesion. At reworking temperatures (above LCST), the adhesive rapidly loses adhesion, enabling easy separation. This parameter-based control resolves the contradiction between maintaining adhesion reliability and enabling easy reworking.
Solution Approach 2:
The adhesive utilizes the lower critical solution temperature (LCST) phase transition phenomenon. Below the LCST, the adhesive components are miscible and provide strong adhesion. Above the LCST, phase separation occurs, causing rapid adhesion loss. This phase transition mechanism enables the adhesive to switch between bonded and separable states, resolving the contradiction between adhesion reliability and reworking ease.
2Ease of repair
If high temperature (100°C or higher) is applied to induce foaming or expansion of thermally expandable material for reworkability, then separation becomes easier, but display device components are damaged
Solution Approach 1:
The invention changes the temperature parameter from conventional high temperature (100°C or higher) to a lower temperature range (50°C to 80°C) corresponding to the LCST of the adhesive composition. This parameter change enables separation without damaging display device components while maintaining reworkability.
Solution Approach 2:
The adhesive acts as a temporary, temperature-responsive bonding agent that can be easily deactivated at low temperature. Rather than using expensive high-temperature processes that risk component damage, the invention employs a disposable-like adhesive that loses its bonding function under controlled low-temperature conditions, enabling safe reworking.
3Ease of repair
If foaming material or thermally expandable material is introduced to achieve reworkability, then separation becomes easier, but adhesion is lowered in temperature range where high adhesiveness is required
Solution Approach 1:
The invention employs phase transition at the LCST point to control adhesion. Below the LCST (in the operating temperature range), the adhesive components remain miscible, providing strong adhesion. At the LCST and above, phase separation occurs, enabling separation. This phase transition mechanism ensures high adhesion in the operating range while enabling reworkability at elevated temperatures.
Solution Approach 2:
The invention replaces mechanical foaming or expansion mechanisms with a chemical phase transition mechanism. Instead of using foaming materials that require high temperature and risk component damage, the invention uses the intrinsic phase transition behavior of the adhesive composition at its LCST, providing a cleaner and more controlled separation mechanism that preserves adhesion in the operating temperature range.
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 ensures excellent adhesion reliability and easy reworking by maintaining adhesion at required temperatures while reducing costs by allowing replacement of only the cover member, and provides excellent folding characteristics across a wide temperature range.
Implementation Method 1
The plasticizer mixture is phase-separated at a temperature equal to or higher than the low critical solution temperature, thereby significantly lowering adhesion of the variable adhesive layer
Implementation Method 2
the plasticizer mixture is present in a single phase at a temperature lower than the low critical solution temperature, the adhesion of the variable adhesive layer is maintained high
Data Source
AI summary
A display device including a display panel, a variable adhesive layer disposed on the display panel and a cover member disposed on the variable adhesive layer is provided. The variable adhesive layer includes a block copolymer and a plasticizer mixture, and the plasticizer mixture has a low critical solution temperature (LCST) of 60° C. to 80° C. The plasticizer mixture is phase-separated into two phases at a temperature equal to or higher than the low critical solution temperature, thereby significantly lowering adhesion of the variable adhesive layer. Accordingly, the display device of the present disclosure has excellent adhesion reliability and provides an advantage of easy reworking since the adhesion significantly decreases at a temperature equal to or higher than the low critical solution temperature. In addition, the display device has excellent folding characteristics due to the presence of the plasticizers.