Micro LED Protective Film Contact Layout for Transfer Misalignment
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Solution Overview
Problem
Organic electronic light emitting display devices face limitations in manufacturing large area displays due to the use of metal shadow masks and suffer from reduced luminance and color purity when combining white light emitting elements with color filters, along with potential transfer defects during micro LED placement.
Innovation Solution
A micro LED display device design featuring a substrate with thin film transistors, micro LEDs with protective films and insulating layers, where the contact holes are sized to allow for misalignment tolerance, preventing lighting malfunctions by ensuring the protective film remains intact even with transfer errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal shadow mask is used to deposit organic light emitting layer, then manufacturing precision is improved, but device complexity and manufacturing cost increase, and large area manufacturing becomes difficult
Solution Approach 1:
The patent extracts and removes the metal shadow mask from the manufacturing process entirely. Instead of using a shadow mask for patterning, the invention employs a self-aligned approach where the pixel electrode pattern itself defines the emission area, eliminating the need for separate shadow mask deposition steps and simplifying the manufacturing process for large area displays
Solution Approach 2:
The patent segments the manufacturing process into separate steps: first forming the pixel electrode pattern on the substrate, then depositing the organic light emitting layer over the entire area, and finally forming contact holes to expose the electrode. This segmentation allows each step to be optimized independently and facilitates large area manufacturing without shadow mask limitations
2Ease of manufacture
If white light emitting element combined with color filter is used, then manufacturing cost and process time are reduced, but luminance and color purity are lowered due to light absorption
Solution Approach 1:
The patent applies local quality by using color conversion layers with specific optical properties positioned only in regions where color conversion is needed, rather than using a general color filter across the entire display. This allows the majority of the light path to remain unobstructed, maintaining high luminance while achieving color purity where required
Solution Approach 2:
The patent changes the optical parameters of the light emitting structure by using micro LEDs with specific wavelength emissions and combining them with color conversion materials that have optimized conversion efficiency. This approach achieves high luminance and color purity simultaneously by selecting materials and structures with favorable optical parameters rather than using conventional white LED plus color filter approaches
3Measurement precision
If contact hole area is reduced for higher resolution, then measurement precision is improved, but transfer error tolerance decreases, increasing lighting malfunction risk
Solution Approach 1:
The patent implements beforehand cushioning by designing the contact hole dimensions and positioning with built-in tolerance margins that accommodate expected transfer errors. The contact holes are positioned and sized to provide a cushion zone that prevents lighting malfunctions even when transfer errors occur, ensuring reliable operation without requiring extremely tight tolerances
Solution Approach 2:
The patent performs preliminary action by establishing the pixel electrode pattern and contact hole positions on the substrate before transferring the micro LEDs. This preliminary structuring creates a robust framework that guides accurate placement and provides tolerance for transfer variations, ensuring reliable electrical connections are formed even with positioning errors
Data Source
AI summary
The present disclosure relates to a micro light emitting diode (LED) display device including a substrate having a plurality of thin film transistors thereon; a plurality of micro light emitting devices (LEDs) on an upper surface of the substrate, the micro LEDs each having a protecting film provided with a first contact hole to expose a portion of an upper surface of a corresponding micro LED; at least one insulating layer covering the micro LED, the insulating layer provided with a second contact hole to expose a portion of the upper surface of the corresponding micro LED; and a connection electrode in the first contact hole and the second contact hole configured to transfer signals to the micro LED, wherein the first contact hole is larger than the second contact hole.