Electrostatic Self-Assembly of Micro LEDs on Warped Substrates
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Solution Overview
Problem
The self-assembly of small-sized light emitting devices on display panels is hindered by non-uniform magnetic field strengths due to substrate warpage, leading to inconsistent pixel luminance, reduced assembly speed, and decreased recovery rates, especially on large substrates.
Innovation Solution
A self-assembly device and method involving a chamber with a fluid where light emitting devices float, a mounting part to secure the substrate, and a voltage supplier to assemble devices by adjusting fluid height and applying voltage, ensuring uniform assembly and high luminance across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a magnet is used to move light emitting devices along the horizontal direction on a large substrate, then light emitting devices near the edge can be assembled, but devices in the central region cannot be assembled due to non-uniform magnetic field strength
Solution Approach 1:
The patent replaces the magnetic field-based self-assembly method with an electric field-based method. A voltage is applied between the substrate and the light emitting devices floating on the fluid surface, generating an electric field that exerts electrostatic force on the devices. This electric field method provides more uniform force distribution across the entire substrate surface, solving the problem of non-uniform assembly in the central region that occurred with magnetic fields.
Solution Approach 2:
The patent changes the physical parameter used for actuation from magnetic field strength to electric field strength (voltage). By controlling the voltage applied between the substrate and light emitting devices, uniform electrostatic force can be achieved across the entire substrate surface, including the central region where magnetic field strength was insufficient. This parameter change enables consistent assembly uniformity throughout the large substrate.
2Ease of operation
If the substrate is disposed parallel to the horizontal surface to enable magnet movement, then the substrate bends downward by gravity, causing non-uniform magnetic field strength
Solution Approach 1:
The patent replaces the magnetic field-based method that requires substrate accessibility with an electric field-based method. The voltage is applied between the substrate and light emitting devices floating on the fluid, creating an electric field that acts uniformly regardless of substrate curvature. This eliminates the problem of substrate bending affecting assembly uniformity.
Solution Approach 2:
The patent introduces a fluid medium as an intermediary between the light emitting devices and the substrate. The devices float on the fluid surface, which provides a stable platform for voltage application and ensures uniform electric field distribution across the substrate surface, compensating for any substrate warpage.
3Manufacturing precision
If light emitting devices are assembled pixel by pixel with high precision, then luminance uniformity improves, but assembly speed decreases
Solution Approach 1:
The patent replaces the magnetic field-based method with an electric field-based method that provides more uniform and stronger forces. The electrostatic force generated by voltage application between the substrate and floating devices enables faster and more reliable assembly while maintaining pixel-level precision, thus improving both speed and accuracy simultaneously.
Solution Approach 2:
The patent changes the actuation parameter from magnetic field strength to voltage-controlled electric field strength. By optimizing the voltage applied, the system achieves both high assembly speed and high precision pixel-level placement, resolving the trade-off between speed and precision that limited the magnetic field-based method.
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
This approach enhances assembly accuracy and speed, achieves uniform luminance, and increases the recovery rate of light emitting devices, reducing manufacturing costs by minimizing defects and improving the assembly process on large substrates.
Implementation Method 1
a voltage supplier configured to apply a voltage to the substrate to assemble the floated plurality of light emitting devices when the height of the fluid decreases from the first height to a second height
Data Source
AI summary
A self-assembly device comprises a chamber configured to accommodate a fluid in which a plurality of light emitting devices are floated on a surface thereof, the fluid having a first height, a mounting part disposed on a bottom portion of the chamber to mount a substrate, a fluid level adjuster configured to adjust a height of the fluid, and a voltage supplier configured to apply a voltage to the substrate to assemble the floated plurality of light emitting devices when the height of the fluid decreases from the first height to a second height.