Micro-LED Display Bonding Support Layer
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Solution Overview
Problem
Micro-LED display devices face challenges such as micro-LED skewing and short circuits during the bonding process due to the small size and fragility of the LEDs, leading to cracking and contact between electrodes.
Innovation Solution
A bonding support layer is introduced between the pads connecting the micro-LED electrodes, which prevents contact and supports the LEDs during bonding and curing, ensuring proper alignment and firm attachment to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If micro-LEDs are transferred to the receiving substrate through bonding process, then the display device can be assembled, but the micro-LEDs are prone to skew and cracks can be generated between electrodes
Solution Approach 1:
A bonding support layer is introduced as an intermediary component between the receiving substrate and the micro-LEDs. This support layer provides mechanical assistance during the bonding process, preventing micro-LED skew and cracking while maintaining ease of manufacture
Solution Approach 2:
The bonding support layer is prepared in advance on the receiving substrate before micro-LED transfer. It provides pre-positioned mechanical support and alignment references that cushion against potential skew and cracking during the bonding process
2Productivity
If the distance between electrodes is reduced to improve pixel density, then more pixels can be packed, but the pads on the receiving substrate can easily contact each other causing short circuit
Solution Approach 1:
The bonding support layer acts as a physical barrier and intermediary structure between adjacent pads on the receiving substrate. It prevents direct contact between pads even when electrode distance is reduced, thereby preventing short circuits while maintaining high pixel density
Solution Approach 2:
The bonding support layer adds a vertical dimension (Z-axis) to the structure, creating physical separation between horizontally adjacent pads. This dimensional approach allows pads to be positioned closer in the XY plane without causing short circuits
3Manufacturing precision
If micro-LEDs are made smaller to improve display resolution, then higher resolution is achieved, but cracks can easily be generated between electrodes during bonding
Solution Approach 1:
The bonding support layer is pre-prepared on the receiving substrate with mechanical properties designed to cushion and support ultra-small micro-LEDs during bonding. This prevents cracks from forming in the fragile structures
Solution Approach 2:
The bonding support layer's mechanical parameters (such as stiffness, thickness, and material properties) are optimized to provide appropriate support for ultra-small micro-LEDs. The layer's parameters are specifically tuned to match the reduced size and increased fragility of smaller LEDs
Data Source
AI summary
The micro-LED display device provided includes a substrate having a first circuit layer and a second circuit layer; a first pad on the first circuit layer and a second pad on the second circuit layer; a plurality of micro-LEDs, wherein each of the micro-LEDs includes a first electrode connected to the first pad and a second electrode connected to the second pad; a first bonding support layer disposed between the first and second pad and in direct contact with the substrate and the micro-LED; and a plurality of second bonding support layers, wherein each of the second bonding support layers includes a lower portion and a upper portion over the lower portion, wherein both portion are disposed between and in lateral contact with adjacent two of the micro-LEDs, and an optical density of the lower portion is greater than that of the upper portion under the same thickness.