MicroLED Suspension Characterization for Defect-Free Fluidic Assembly
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Solution Overview
Problem
Conventional suspension handling techniques are not compatible with the unique properties of microLEDs, leading to rapid settling, stiction issues, and mechanical fragility, which complicates the fluidic assembly process for microLED displays, resulting in inefficiencies and high costs due to defective microLEDs and cross-contamination.
Innovation Solution
A selective harvest method and dispensing system are developed to create a uniform microLED suspension by separating defective devices, using solvent-resistant binding materials and optical inspection, and optimizing the suspension's concentration and homogeneity, ensuring minimal damage and loss during handling and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional suspension handling techniques are used for microLEDs, then the assembly process can proceed, but rapid settling, stiction issues, and mechanical fragility occur leading to defects and cross-contamination
Solution Approach 1:
The patent modifies physical parameters of the suspension system including viscosity control through specific carrier fluid selection, particle size distribution optimization, and concentration adjustments to achieve stable suspension that prevents rapid settling while maintaining fluidity for assembly operations
Solution Approach 2:
The patent introduces carrier fluids as intermediary substances that mediate between microLED particles and the assembly environment, providing controlled viscosity and surface properties that prevent stiction and mechanical damage during handling and assembly
2Productivity
If defective microLEDs are not identified and removed, then the suspension can be used directly for assembly, but defective microLEDs create defective subpixels reducing display quality
Solution Approach 1:
The patent implements preliminary characterization and sorting of microLEDs before assembly, using optical inspection and electrical testing to identify and remove defective devices in advance, ensuring only functional microLEDs enter the suspension for assembly
Solution Approach 2:
The patent incorporates feedback mechanisms through real-time monitoring of suspension quality parameters and inspection systems that detect defective microLEDs, providing continuous information for adjusting the characterization and sorting processes to maintain high display quality
3Reliability
If mechanical pick-and-place tools are used to remove defective microLEDs, then defective devices can be replaced, but the tools are expensive to buy and operate
Solution Approach 1:
The patent replaces mechanical pick-and-place tools with fluidic-based characterization and sorting systems that use carrier fluid dynamics, optical detection, and electrical testing to identify and separate defective microLEDs, eliminating the need for expensive mechanical manipulation equipment
Solution Approach 2:
The patent employs hydraulic and pneumatic principles through carrier fluid flow control to manipulate and separate microLEDs based on their properties, using fluid dynamics rather than mechanical contact to achieve defect correction with lower equipment costs
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 system effectively produces a uniform distribution of functional microLEDs on the display substrate, reducing defects and costs by preventing defective microLEDs from entering the assembly process and ensuring precise control over microLED placement, thereby enhancing the efficiency and quality of microLED displays.
Implementation Method 1
a system for characterizing a micro-light emitting diode (microLED) suspension... optically measures the suspension opacity at a plurality of container heights
Data Source
AI summary
A method is provided for the selective harvest of microLED devices from a carrier substrate. Defect regions are predetermined that include a plurality of adjacent defective microLED devices on a carrier substrate. A solvent-resistant binding material is formed overlying the predetermined defect regions and exposed adhesive is dissolved with an adhesive dissolving solvent. Non-defective microLED devices located outside the predetermined defect regions are separated from the carrier substrate while adhesive attachment is maintained between the microLED devices inside the predetermined defect regions and the carrier substrate. Methods are also provided for the dispersal of microLED devices on an emissive display panel by initially optically measuring a suspension of microLEDs to determine suspension homogeneity and calculate the number of microLEDs per unit volume. If the number of harvested microLED devices in the suspension is known, a calculation can be made of the number of microLED devices per unit of suspension volume.