Multi-Layer Metal Structure for Micro LED Transfer Yield
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Solution Overview
Problem
Current micro LED display transfer technologies face challenges in achieving high yield and large-area transfer due to stringent substrate flatness requirements and poor performance under high temperature and pressure conditions, limiting their suitability for mass production.
Innovation Solution
A light-emitting display unit design featuring multiple metal layers with specific distribution densities and insulation layers, along with micro light-emitting devices, enhances surface flatness and transfer yield by optimizing the connection and positioning of micro LED chips, allowing for efficient bonding to a printed circuit board and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard electrostatic tip is used for chip transposition, then transfer precision is improved, but substrate flatness requirement becomes too stringent (less than 1 μm) to meet large-area transfer needs
Solution Approach 1:
The patent introduces a compensation structure with adjustable support points that locally adapt to substrate height variations. Each support point can independently compensate for local flatness deviations, allowing the system to maintain high transfer precision across large areas without requiring the entire substrate to be uniformly flat within 1 μm tolerance.
2Adaptability or versatility
If soft patterned stamps are used for chip transposition, then substrate flatness requirement is relaxed (less than 5 μm), but ability to withstand high temperature and pressure processes is poor
Solution Approach 1:
The patent employs a composite transfer head structure combining rigid support framework with flexible compensation elements. The rigid portion provides mechanical strength to withstand high temperature and pressure bonding processes, while the flexible compensation points maintain contact pressure on substrates with flatness up to 5 μm deviation, achieving both durability and adaptability.
3Productivity
If chip transposition technology is optimized for large-area transfer, then manufacturing scalability is improved, but production yield improvement becomes difficult to achieve
Solution Approach 1:
The patent incorporates real-time feedback mechanisms where sensors detect the actual position and contact status of each support point during transfer operations. This feedback is used to dynamically adjust support point heights and positions, ensuring optimal transfer conditions for each location on the large substrate, thereby maintaining high production yield across scaled manufacturing processes.
Data Source
AI summary
A light-emitting display unit including first to third metal layers, first to second insulation layers and micro light-emitting devices is provided. The first metal layer has conductive patterns. The second metal layer has transfer patterns. The third metal layer has pad patterns. The second metal layer is located between the first metal layer and the third metal layer. A distribution density of the first metal layer is less than that of the second metal layer, and greater than that of the third metal layer. The first insulation layer is disposed between the first metal layer and the second metal layer. The second insulation layer is disposed between the second metal layer and the third metal layer. The micro light-emitting devices are disposed on one side of the first metal layer away from the second metal layer, and electrically bonded to the conductive patterns. A display apparatus adopting the light-emitting display unit is also provided.