Micro LED Display Layout for Planar Transfer and Moisture Resistance
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Solution Overview
Problem
Micro LED displays face issues such as spot defects, moisture infiltration, and cracking due to the thickness of organic insulating layers, especially in flexible or bendable areas, which affect reliability and manufacturing efficiency.
Innovation Solution
The design minimizes the thickness of organic insulating layers above pixel driving circuits, places connection lines lower than the pixel circuits, uses stress-relief patterns in wiring, and employs a multi-layer structure for signal routing, with transparent conductive second electrodes and a shared driving circuit to improve durability and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of organic insulating layers is increased to provide better insulation, then insulation performance is improved, but spot defects and transfer defects of micro LED occur due to flowing-down of the organic insulating layer
Solution Approach 1:
The patent applies different thickness specifications for organic insulating layers at different locations: a first thickness in a first region and a second thickness (different from the first) in a second region. This local differentiation prevents the flowing-down effect that causes micro LED placement defects while maintaining adequate insulation where needed.
2Object-affected harmful factors
If the thickness of organic insulating layers is increased to prevent moisture infiltration, then moisture protection is improved, but cracks are generated in the organic insulating layers reducing reliability
Solution Approach 1:
The patent specifies different thicknesses for organic insulating layers in different regions to prevent crack formation. By optimizing the thickness locally rather than uniformly increasing it, the patent maintains moisture protection while avoiding the stress concentration that leads to cracking.
3Reliability
If the thickness of organic insulating layers is increased to improve insulation, then insulation performance is improved, but moisture permeation increases due to layer defects
Solution Approach 1:
The patent uses location-specific thickness control of organic insulating layers to prevent defects such as flowing-down and cracking. This ensures continuous, defect-free insulation layers that effectively block moisture permeation while maintaining adequate insulation performance.
4Ease of manufacture
If connection lines are placed at the same height as pixel circuits, then routing is simplified, but the surface is uneven causing inaccurate LED placement
Solution Approach 1:
The patent resolves the height conflict between connection lines and pixel circuits by introducing an additional organic insulating layer that fills the height difference. This planarization approach creates a flat surface for accurate LED placement while maintaining simplified routing through the insulating layer.
Data Source
AI summary
According to an aspect of the present disclosure, a display apparatus includes a substrate having a plurality of pixel driving circuits thereon. An over coating layer encloses the plurality of pixel driving circuits on the substrate, and a 1-1-th connection line is disposed on the over coating layer and electrically connected to the plurality of pixel driving circuits. A plurality of organic insulating layers is disposed on the pixel driving circuits, the over coating layer, and the 1-1-th connection line. A plurality of banks is disposed on the plurality of organic insulating layers, and a plurality of micro LEDs is disposed on the plurality of banks and electrically connected to the pixel driving circuits. The 1-1-th connection line is positioned such that its height is lower than the top surface of the pixel driving circuit. This structure helps to improve surface planarity and facilitates reliable micro LED transfer and electrical connection.