Sub-Pixel LED Display Assembly Using Dielectrophoretic Adhesive Particles
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Solution Overview
Problem
The challenge lies in forming adhesive patterns at the sub-pixel level in display devices with ultra-small pixels, as existing methods face difficulties in precise alignment and misalignment issues, leading to bonding and wiring defects, especially with the trend towards higher resolution displays.
Innovation Solution
The use of dielectrophoretic forces to control adhesive particles for forming an adhesive part within sub-pixel units, allowing for precise assembly and fixation of semiconductor light emitting devices on a substrate, utilizing a method that includes applying specific voltages to assembling wirings to guide adhesive particles into assembly holes and assemble light emitting devices, followed by curing and cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photoresist film is disposed around light emitting device to fix it, then light emitting device can be fixed, but light emitting device is separated or lifted off due to substrate rotation, resulting in bonding defects or wiring connection defects
Solution Approach 1:
The patent replaces the mechanical spin-coating process with a dielectrophoretic field-based process. Adhesive particles are positioned using electric fields generated by electrodes, eliminating the need for substrate rotation. This substitution of mechanical positioning with field-based positioning resolves the contradiction by maintaining fixation reliability without the harmful mechanical rotation that causes misalignment.
Solution Approach 2:
The patent introduces adhesive particles as intermediaries between the light emitting device and the substrate. These particles are precisely positioned using dielectrophoretic forces to form an adhesive part that secures the device. This intermediary approach allows fixation without direct mechanical contact during positioning, avoiding the alignment issues caused by substrate rotation.
2Reliability
If adhesive pattern is formed on pixel on substrate, then light emitting device can be fixed, but adhesive pattern is not formed within pixel but in area between pixels due to misalignment, resulting in additional defects
Solution Approach 1:
The patent replaces mechanical pattern formation methods with dielectrophoretic field-based particle positioning. The adhesive particles are precisely controlled by electric fields to form adhesive parts exactly where needed within each pixel, eliminating misalignment issues inherent in mechanical patterning processes.
Solution Approach 2:
The patent applies local quality by positioning adhesive particles specifically within each pixel area using localized electric fields. The dielectrophoretic forces are confined to specific regions, ensuring adhesive parts are formed only where required rather than uniformly across the substrate, thus preventing defects in inter-pixel areas.
3Ease of manufacture
If substrate is rotated for spin coating photoresist film, then photoresist film can be formed, but light emitting device is separated or lifted off, resulting in bonding defects or wiring connection defects
Solution Approach 1:
The patent replaces the mechanical spin-coating process with a dielectrophoretic field-based particle positioning process. Instead of rotating the substrate to form a film, electric fields are used to position adhesive particles directly where needed. This eliminates the mechanical rotation that causes light emitting devices to separate or lift off, thereby maintaining bonding reliability while achieving film formation.
4Manufacturing precision
If pixel size is reduced for high resolution, then display resolution is improved, but it becomes very difficult to form adhesive pattern in sub-pixel basis, resulting in misalignment and additional defects
Solution Approach 1:
The patent replaces mechanical adhesive pattern formation with dielectrophoretic field-based particle positioning. This field-based approach can precisely control particle positions even at sub-pixel scales, making adhesive pattern formation feasible for ultra-high resolution displays where mechanical methods fail.
Solution Approach 2:
The patent changes the fundamental parameter of adhesive application from mechanical deposition to field-based particle manipulation. By using dielectrophoretic forces, the system can achieve the precise positioning required for sub-pixel adhesive patterns in ultra-high resolution displays, overcoming the limitations of mechanical methods at small scales.
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 approach enables reliable fixation of light emitting devices, improving yield and lighting performance by preventing separation during post-processing, reducing manufacturing costs, and enhancing product reliability through precise particle-level control and simplified assembly processes.
Implementation Method 1
the adhesive part comprises adhesive particles in contact with each other... forming an adhesive part in sub-pixel units through particle-level control... using dielectrophoretic forces not only for assembling a semiconductor light emitting device but also for forming an adhesive part
Data Source
AI summary
The display device can include a substrate; a barrier rib disposed on the substrate and having an assembly hole; a semiconductor light emitting device in the assembly hole; and an adhesive part between the substrate and the semiconductor light emitting device within the assembly hole. The adhesive part can include adhesive particles in contact with each other.