Multi-Layer Display Adhesives for OLED-Safe Glass Debonding
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Solution Overview
Problem
Conventional portable information handling systems, such as smartphones and tablets, face challenges in repairing their display assemblies due to the high temperatures and mechanical forces required for debonding the glass cover, which can damage fragile OLED substrates.
Innovation Solution
A multi-layer display assembly apparatus is introduced, featuring multiple transparent adhesive layers with different indices of refraction and debonding characteristics, allowing for selective debonding of the glass cover without damaging the display substrate, using a combination of thermoplastic and thermoset adhesives with distinct curing mechanisms and debonding conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single layer adhesive is used to bond the glass cover to the display substrate, then the bonding process is simple, but the repair process requires high temperature (at or above 100° C.) and UV light to debond the adhesive, which can damage the fragile OLED substrate
Solution Approach 1:
The single adhesive layer is segmented into multiple adhesive layers with different debonding characteristics. The first adhesive layer (closer to glass) debonds at lower temperatures, while the second adhesive layer (closer to substrate) maintains stronger bonding, enabling selective debonding that protects the OLED substrate from damage during repair.
Solution Approach 2:
Different regions of the adhesive system have different properties - the first adhesive layer has lower glass transition temperature and different UV absorption characteristics compared to the second adhesive layer. This local differentiation allows the repair process to target specific layers, enabling glass removal without exposing the substrate to damaging conditions.
2Ease of repair
If high temperature heat is applied to debond the adhesive layer, then the glass cover can be removed from the display substrate, but the high temperature can damage the fragile OLED substrate
Solution Approach 1:
The adhesive layers are formulated with different glass transition temperatures - the first adhesive layer has a lower Tg than the second adhesive layer. This parameter differentiation allows selective debonding at controlled temperatures, enabling glass removal at temperatures that protect the OLED substrate from thermal damage.
Solution Approach 2:
The adhesive system is segmented into layers with progressively higher thermal stability closer to the substrate. This segmentation creates a thermal buffer zone where the first adhesive layer debonds at lower temperatures, preventing heat transmission to the sensitive OLED substrate while still enabling glass cover removal.
3Ease of repair
If UV light is applied to activate adhesive debonding, then the adhesive layer can be debonded from the glass cover interface, but the UV light wavelength must be precisely controlled to avoid damaging the display substrate
Solution Approach 1:
The adhesive layers have different UV absorption characteristics - the first adhesive layer absorbs UV light at specific wavelengths more strongly than the second adhesive layer. This local optical property differentiation enables selective activation of the first adhesive layer for debonding without exposing the substrate to damaging UV exposure.
Solution Approach 2:
The adhesive formulations use different UV-curable chemistry or UV absorption spectra. This parameter change in optical properties allows the repair system to use UV wavelengths that activate the first adhesive layer for debonding while leaving the second adhesive layer and substrate unaffected, preventing UV damage to the display substrate.
4Ease of repair
If multiple adhesive layers with different indices of refraction are used, then selective debonding is enabled, but the device complexity increases
Solution Approach 1:
The adhesive system is segmented into multiple thin layers rather than one thick layer. Each layer is relatively simple in composition but collectively they provide the selective debonding functionality. This segmentation achieves complex repair capability through simple, modular layering.
Solution Approach 2:
The patent uses composite adhesive materials with different optical and thermal properties in each layer. These composite materials are designed to work together as a system, where the combination of layers provides selective debonding capability that neither layer could achieve alone, balancing complexity with functionality.
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 solution enables safe and efficient removal and replacement of the glass cover without damaging the OLED substrate, maintaining the structural integrity and optical performance of the display assembly, and is suitable for both repair and replacement processes.
Implementation Method 1
an applied UV light having a first wavelength (such as 248 nanometers) passes through the glass cover mostly unabsorbed and is primarily absorbed by the adhesive layer to activate ablation and debonding at the glass/adhesive interface
Implementation Method 2
an applied UV light having a second wavelength (such as 308 nanometers) passes through both the glass cover and the adhesive layer mostly unabsorbed to the underlying display substrate where it is absorbed and activates ablation and debonding at the adhesive/display substrate interface
Implementation Method 3
multiple transparent adhesive layers (e.g., two or more transparent adhesive layers) that have different indices of refraction and/or different debonding characteristics
Data Source
AI summary
Apparatus and methods may be implemented to provide multi-layer display assembly apparatus for information handling systems, including portable information handling systems (e.g., such as smart phones, tablet computers, notebook computers, etc.) as well as display assembly apparatus for other types of information handling systems such as desktop computers, servers, etc. The disclosed multi-layer display assembly apparatus may be implemented to include multiple adhesive layers (e.g., two or more adhesive layers) that have different indices of refraction and/or different debonding characteristics, and that are disposed between a display substrate and an transparent protective hardcover such as glass-based or plastic-based cover.