Ultra-Thin Pin LED Assembly for Self-Aligned Full-Color Displays
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Solution Overview
Problem
Current micro-LED and nano-LED technologies face challenges in manufacturing high-resolution displays due to limitations in process technology, leading to high unit prices, high defect rates, and low productivity, particularly in achieving desired luminous efficiency and surface defect minimization, with issues in self-alignment and electrical short circuits during dielectrophoresis.
Innovation Solution
The development of a full-color LED display using ultra-thin pin LED devices with layers stacked perpendicular to the major axis, allowing for self-alignment with a specific surface contacting the electrode, reducing surface defects, and enabling DC power driving by optimizing the structure and material properties to enhance luminance and mounting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nanorod-type LED devices are used with major axis coinciding with layer stack direction, then self-alignment is achieved through dielectrophoresis, but emission area is narrow and surface defects have large effect on efficiency degradation
Solution Approach 1:
The patent inverts the conventional orientation of nanorod-type LED devices by rotating them 90 degrees so that the major axis becomes perpendicular to the layer stack direction. This inversion allows the broader side surface to contact the electrode instead of the narrow top surface, significantly increasing the emission area and reducing the impact of surface defects on luminous efficiency while maintaining self-alignment capability through dielectrophoresis
2Shape
If wafer etching is performed to create nanorod-type LED devices, then desired shape is achieved, but surface defects occur due to extensive etching and separation difficulty arises
Solution Approach 1:
The patent applies preliminary protective coating to the wafer surface before etching, and uses controlled etching depth to create nanorod structures with minimized surface exposure. This preliminary protection and controlled processing reduce surface defect formation during etching while maintaining the desired nanorod shape
3Ease of manufacture
If side surface of LED device is self-aligned to contact electrode, then mounting is simplified, but electrical short occurs when driving power is applied
Solution Approach 1:
The patent utilizes the asymmetric structure of the nanorod LED device where the side surface has different electrical properties compared to the top and bottom surfaces. By orienting the device so that the side surface contacts the electrode, the patent achieves easy mounting while the asymmetric electrical characteristics prevent short circuits during operation
4Manufacturing precision
If pick and place technology is used for micro-LED assembly, then individual placement is achieved, but productivity is low and unit price is high
Solution Approach 1:
The patent enables nanorod LED devices to self-align and self-assemble on the electrode through dielectrophoresis when exposed to an electric field. This self-service mechanism eliminates the need for complex pick and place equipment, significantly increasing productivity and reducing unit price while maintaining precise placement through the inherent alignment properties of the nanorod structures
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 increases luminance and light efficiency by minimizing surface defects and electrical shorts, while improving the drivable mounting ratio and allowing for DC power driving, thus enhancing the overall performance and cost-effectiveness of the LED display.
Implementation Method 1
applying assembly power to the lower electrode line to self-align each of the ultra-thin pin LED devices input into each of the sub-pixel sites on the lower electrode line
Data Source
AI summary
The present invention relates to a full-color LED display. According to the present invention, a surface of an ultra-thin pin LED device in contact with an electrode through dielectrophoresis becomes a surface rather than a side surface, thereby increasing a drivable mounting efficiency, which is advantageous for achieving a higher luminance full-color LED display.