Micro LED Self-Assembly With Concave-Convex Bonding

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Solution Overview

Problem

The challenge lies in efficiently transferring and assembling millions of micro-sized semiconductor light emitting devices for large-screen displays without high costs, while addressing issues such as bending and separation from substrates due to gravity and friction.

Innovation Solution

A self-assembly method utilizing concave-convex structures on semiconductor light emitting devices and dielectric layers, combined with magnetic and electric fields, to facilitate precise placement and bonding, enhancing van der Waals and electric forces for stable attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a pick and place method or laser lift-off method is used to transfer semiconductor light emitting devices, then the transfer precision can be improved, but the manufacturing cost and process complexity increase significantly

Engineering Contradiction:
Improvetransfer precisionVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The semiconductor light emitting device performs the transfer process itself through self-assembly in a fluid environment. The device utilizes its own physical and chemical properties (surface tension, buoyancy, magnetic response) to achieve positioning and attachment without external manipulation tools, thereby eliminating complex pick-and-place equipment and laser lift-off systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical transfer systems (pick and place robots, laser lift-off apparatus) with a fluid-based self-assembly system. The transfer process is achieved through hydrodynamic forces, surface tension effects, and magnetic field guidance rather than mechanical grasping or laser ablation, significantly simplifying the equipment required.

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

2Area of stationary object

If micro LED devices are assembled on a large-area substrate, then the display area increases, but the devices may separate from the substrate due to gravity and friction

Engineering Contradiction:
Improvedisplay areaVSAvoidattachment stability
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces a dielectric layer as an intermediary between the semiconductor light emitting device and the substrate. This intermediate layer provides enhanced adhesion through van der Waals forces and electrostatic attraction, preventing device separation while accommodating large display areas. The dielectric layer acts as a bonding mediator that strengthens the device-substrate interface.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the physical and chemical parameters of the substrate interface by applying electrostatic fields and utilizing dielectric properties. By controlling electrostatic attraction forces and van der Waals interactions through the dielectric layer, the attachment stability is enhanced to prevent device separation under gravity and friction conditions.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional transfer methods are used, then the transfer process can be controlled, but the manufacturing cost increases and the transfer speed decreases

Engineering Contradiction:
Improvetransfer controlVSAvoidtransfer speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The self-assembly process enables millions of devices to automatically position and attach themselves simultaneously through fluid dynamics and field effects. This parallel self-organization eliminates the sequential nature of conventional pick-and-place methods, achieving both high speed and reliable control without requiring complex real-time manipulation of each individual device.

Inventive Principle:
Principle #25Self-service

4Use of energy by moving object

If micro LED devices are used for display, then the light emission efficiency improves, but the difficulty of transferring and assembling the devices increases

Engineering Contradiction:
Improvelight emission efficiencyVSAvoidtransfer difficulty
Core Design Contradiction:
Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent replaces difficult mechanical handling of micro LED devices with a fluid-based self-assembly system. The tiny devices are manipulated through hydrodynamic forces, buoyancy control, and magnetic field guidance rather than mechanical grippers, making the transfer process as easy as handling larger components despite the micro-scale dimensions.

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

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 low-cost, high-efficiency, and high-speed transfer of semiconductor light emitting devices, preventing separation and improving heat dissipation, resulting in a large-area display device with increased light reflection and reduced defects.

Implementation Method 1

enhancing van der Waals and electric forces for stable attachment

Methodology Applied
Scientific Effectvan der Waals force: Van der Waals Force

Implementation Method 2

combined with magnetic and electric fields, to facilitate precise placement and bonding

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 3

combined with magnetic and electric fields, to facilitate precise placement and bonding

Methodology Applied
Scientific EffectElectric field: Electric Field

Data Source

PatentEP4068366B1Display device using micro LED
Publication Date: 2025.09.10 LG ELECTRONICS INC
  • EP4068366B1 patent drawingFigure 1
  • EP4068366B1 patent drawingFigure 2~3
  • EP4068366B1 patent drawingFigure 4~5b

AI summary

The present invention relates to a display device, and more particularly, to a display device using a semiconductor light emitting device having a size of several µm to several tens of µm. The present invention can provide a display device characterized in that it includes a base part, a plurality of assembly electrodes disposed on the base part, and having a first electrode and a second electrode that generate an electric field when power is applied, a dielectric layer formed to cover the assembly electrodes and a plurality of semiconductor light emitting devices disposed on a surface of the dielectric layer, and a concave-convex structure formed on one surface of the semiconductor light emitting device facing the dielectric layer and one surface of the dielectric layer facing the semiconductor light emitting device, respectively.