Micro-LED Assembly Electrodes for DEP Transfer Yield
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Solution Overview
Problem
Micro-LED displays face challenges in rapid and accurate transfer of millions of micro-LEDs due to high transfer error rates and reduced electrical contact characteristics, particularly with the self-assembly method using dielectrophoresis (DEP), which results in low assembly yield and lighting efficiency.
Innovation Solution
A display device design incorporating a substrate with assembly electrodes, insulating layers, and a plating layer that includes a protruding semiconductor layer to enhance electrical connection and DEP force control, ensuring precise positioning and even power distribution for improved electrical contact and assembly efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-assembly method using dielectrophoresis (DEP) is used to transfer micro-LEDs, then transfer speed is improved, but transfer error rate increases and assembly yield decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform electric field through specifically designed electrode structures (interdigitated electrodes with optimized spacing and geometry) that generate localized dielectrophoresis forces. This allows precise control of DEP force distribution across the substrate, enabling high-speed transfer while maintaining positioning accuracy and reducing transfer errors through localized field optimization.
Solution Approach 2:
The patent employs parameter changes by optimizing multiple DEP-related parameters including electric field frequency, voltage amplitude, electrode spacing, and fluid conductivity. By carefully tuning these parameters, the system achieves rapid micro-LED transfer while minimizing transfer errors through precise control of the dielectrophoresis force magnitude and distribution.
2Productivity
If DEP force is used for self-assembly, then assembly speed is improved, but semiconductor light emitting device tilts to different locations in assembly hole reducing electrical contact characteristics
Solution Approach 1:
The patent uses local quality by designing electrode patterns that create concentrated DEP force zones precisely at the center of assembly holes. The interdigitated electrode geometry and spacing are optimized to generate localized electric field gradients that push micro-LEDs to specific positions within the holes, ensuring uniform orientation and proper electrical contact while maintaining fast assembly speed.
Solution Approach 2:
The patent applies equipotentiality principles by designing the electrode structure and applying voltages such that equipotential lines are positioned to guide micro-LEDs to correct orientations. The electric field distribution is engineered to create potential energy minima at desired positions within assembly holes, ensuring uniform positioning and electrical contact across all devices during rapid assembly.
3Productivity
If DEP force distribution is strongly formed inside and on upper side of assembly hole, then self-assembly is achieved, but semiconductor light emitting device blocks entrance to assembly hole
Solution Approach 1:
The patent applies segmentation by dividing the electric field generation into multiple independent electrode segments (interdigitated fingers) that can create differentiated DEP force distributions. This segmentation allows the electric field to be concentrated inside the assembly hole while minimizing field strength at the entrance, enabling self-assembly without blocking the entry path for micro-LEDs.
Solution Approach 2:
The patent uses dimensionality change by designing the electrode structure to create vertical electric field gradients that concentrate DEP forces deep within the assembly hole rather than at the surface level. This vertical dimensionality control allows strong assembly forces inside the hole while keeping the entrance region relatively free of obstructing forces, facilitating easy device entry.
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 significantly improves electrical contact reliability, reduces assembly defects, and enhances luminance by evenly applying power and controlling the vertical direction of micro-LEDs, thereby increasing assembly yield and lighting performance.
Implementation Method 1
a self-assembly method using dielectrophoresis (DEP)... the distribution of DEP force is strongly formed not only inside the assembly hole but also on the upper side of the assembly hole during self-assembly
Data Source
AI summary
Discussed is a display device including a semiconductor light emitting device. A display device can include a substrate, first assembly electrodes, second assembly electrodes and the first assembly electrodes spaced apart from each other on the substrate, an insulating layer disposed on the second assembly electrode, an assembly barrier wall including a predetermined assembly hole and disposed on the insulating layer, a plating layer electrically connected to the first assembly electrode and the second assembly electrode, and a semiconductor light emitting device disposed in the assembly hole and electrically connected to the first assembly electrode and the second assembly electrode by the plating layer.