Micro LED Electrode Structure for Reliable Self-Alignment
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Solution Overview
Problem
Existing display technologies, such as LCDs and AMOLEDs, face challenges with flexibility, response time, yield, and assembly reliability of micro LEDs due to weak capillary forces and misalignment during self-assembly.
Innovation Solution
A display device structure that includes a substrate with metal pads and semiconductor light emitting devices connected through self-assembly, featuring a conductive electrode exposed via a passivation layer through-hole, with specific width ratios and magnetic/mating mechanisms to ensure precise alignment and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If self-alignment using capillary force is used to align micro LED to lower wiring, then alignment is achieved, but the probability of self-aligned micro LED is lowered due to weak capillary force, reducing yield
Solution Approach 1:
The patent changes the physical parameters of the lower wiring structure by introducing a protrusion with specific dimensions (width W1, length L1) and a recess with corresponding dimensions. This geometric parameter modification enhances the capillary force effect during self-assembly, allowing micro LEDs to align reliably with the lower wiring without requiring excessively strong external forces.
Solution Approach 2:
The patent introduces an intermediary structure consisting of the protrusion and recess that mediates the alignment between micro LED and lower wiring. This intermediary geometric feature acts as a physical guide that enhances the natural capillary force, enabling reliable self-alignment without directly applying external force to the micro LED.
2Manufacturing precision
If a single micro LED is aligned in a single pixel region, then precise alignment is achieved, but a plurality of micro LEDs are arranged in one pixel region, causing defects during assembly
Solution Approach 1:
The patent applies local quality by creating distinct geometric features (protrusions and recesses) at specific locations within the pixel region. These localized structural variations guide micro LEDs to specific positions, ensuring that multiple micro LEDs are distributed correctly across the pixel region rather than clustering in one area, thus preventing assembly defects.
Solution Approach 2:
The patent segments the pixel region into multiple designated areas using the protrusion-recess structure. This segmentation creates defined zones where micro LEDs should be positioned, preventing multiple micro LEDs from incorrectly occupying the same space and ensuring proper spatial distribution for high-yield assembly.
3Area of stationary object
If micro LED is made small for large area display, then display area is increased, but arrangement becomes difficult due to small size
Solution Approach 1:
The patent introduces protrusions and recesses as intermediary structures that act as physical guides for placing small micro LEDs. These geometric features provide tactile and capillary force-based guidance that makes arranging tiny micro LEDs significantly easier, compensating for their small size without requiring complex external manipulation equipment.
Solution Approach 2:
The patent enables self-service arrangement where the protrusion-recess structure automatically guides micro LEDs into correct positions through capillary forces during the assembly process. This self-aligning mechanism eliminates the need for precise external positioning equipment, making the arrangement of small micro LEDs straightforward and scalable for large area displays.
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
Improves assembly reliability, enhances yield, and enables high-speed, flexible displays with efficient electrical connections and long lifespan without the need for a backlight unit, allowing for high brightness and fast response times.
Implementation Method 1
a plurality of semiconductor light emitting devices electrically connected to the metal pads through self-assembly
Implementation Method 2
self alignment using a capillary force has been used when aligning the micro LED to the lower wiring
Data Source
AI summary
A display device, including a substrate having a plurality of metal pads; and a plurality of semiconductor light emitting devices electrically connected to the metal pads. A respective semiconductor light emitting device includes an n-type semiconductor layer, an active layer and a p-type semiconductor layer, a conductive electrode on the p-type semiconductor layer; and a passivation layer configured to surround the respective semiconductor light emitting device and including a through hole through which the conductive electrode is exposed. Further, the conductive electrode includes a protruding portion protruding through the through hole of the passivation layer and overlapping outer surfaces of the passivation layer. Also, the protruding portion of the conductive electrode contacts a corresponding metal pad, and a width of the protruding portion of the conductive electrode is greater than a width of the corresponding metal pad.