MicroLED Self-Assembly Using Buoyancy and Magnetic Positioning

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Solution Overview

Problem

Current methods for self-assembling microLEDs in large-screen displays face challenges such as warpage of substrates due to gravity and non-uniform dispersion of microLEDs, leading to low transfer yields and stability issues during the self-assembly process.

Innovation Solution

A device and method utilizing a magnetic field and electric field to position microLEDs on a substrate, with a substrate chuck that submerges the substrate in fluid to apply buoyancy and correct warpage, and a chip supply part to ensure uniform dispersion of microLEDs, allowing for high-yield self-assembly without additional equipment or processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If self-assembly method is used for microLED transfer, then productivity is improved, but manufacturing precision deteriorates due to non-uniform dispersion and warpage

Engineering Contradiction:
Improvetransfer efficiencyVSAvoidpositioning accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies buoyancy force from fluid to counteract gravitational force on the substrate, preventing warpage during self-assembly. The substrate is positioned in a fluid environment where the upward buoyant force balances the downward gravitational force, maintaining substrate flatness and enabling precise microLED positioning.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent replaces mechanical transfer methods with magnetic field-based positioning. Magnetic fields are used to manipulate and position microLEDs on the substrate without physical contact, eliminating mechanical errors and achieving high positioning precision while maintaining the efficiency of self-assembly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If substrate area is increased for large-screen displays, then productivity is improved, but stability deteriorates due to warpage and non-uniform microLED distribution

Engineering Contradiction:
Improvedisplay areaVSAvoidsubstrate uniformity
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

For large-area substrates, the patent uses fluid buoyancy to counteract gravity across the entire substrate surface, preventing warpage and maintaining uniform flatness. This enables stable self-assembly of microLEDs across large display areas without positional deviations or non-uniform distribution.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Manufacturing precision

If conventional transfer methods are used, then manufacturing precision is improved, but productivity deteriorates due to complex processes and additional equipment

Engineering Contradiction:
Improvepositioning accuracyVSAvoidtransfer efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces complex mechanical transfer systems with a simplified magnetic field-based approach. Magnetic fields enable direct positioning of microLEDs on the substrate without mechanical contact, reducing process complexity and equipment requirements while achieving high positioning accuracy and transfer efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent enables microLEDs to self-position on the substrate through magnetic field guidance and fluid buoyancy. The system allows microLEDs to find their correct positions autonomously without complex mechanical manipulation, simplifying the transfer process and improving productivity while maintaining precision.

Inventive Principle:
Principle #25Self-service

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

Enables efficient, low-cost, and high-yield self-assembly of microLEDs on large-area substrates, improving transfer efficiency and reducing substrate warpage, while preventing non-specific binding and adherence.

Implementation Method 1

a magnetic field forming part having a plurality of magnets for applying magnetic force to the semiconductor light-emitting diodes dispersed in the fluid

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Implementation Method 2

an electrode connection part for applying power to the assembly electrode to generate an electric field so that the semiconductor light-emitting diodes are placed at predetermined positions

Methodology Applied
Scientific EffectElectric field: Electric Field

Implementation Method 3

the vertical moving part provided at the substrate chuck lowers the substrate to the fluid so that buoyancy by the fluid is applied to the substrate

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP3796382B1Device for self-assembling semiconductor light-emitting diodes
Publication Date: 2023.08.30 LG ELECTRONICS INC
  • EP3796382B1 patent drawingFigure 1
  • EP3796382B1 patent drawingFigure 2
  • EP3796382B1 patent drawingFigure 3~4

AI summary

The present disclosure provides a device for self-assembling semiconductor light-emitting diodes, which includes: an assembly chamber having a space for accommodating a fluid, a magnetic field forming part having a plurality of magnets for applying magnetic force to the semiconductor light-emitting diodes dispersed in the fluid and a horizontal moving part for changing a positions of the magnets so that the semiconductor light-emitting diodes move in the fluid, and a substrate chuck having a substrate support part configured to support a substrate having an assembly electrode, a vertical moving part for lowering the substrate so that one surface of the substrate is in contact with the fluid in a state in which the substrate is supported, and an electrode connection part for applying power to the assembly electrode to generate an electric field so that the semiconductor light-emitting diodes are placed at predetermined positions of the substrate in a process of moving by a position change of the magnets, wherein the vertical moving part provided at the substrate chuck lowers the substrate to the fluid so that buoyancy by the fluid is applied to the substrate.