Transfer Roller Electrode Structure for High-Yield Micro-LED Assembly

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Solution Overview

Problem

Existing micro-LED display technologies face challenges in quickly and accurately transferring millions of semiconductor light emitting devices to a display panel, leading to increased transfer error rates and reduced yield, while attempts to improve yield result in slower transfer speeds.

Innovation Solution

An intelligent assembly-transfer integration device with a roller part featuring a roller pad electrode structure that includes penetration electrodes and adhesive films, along with a magnet head for precise assembly and inspection, ensuring only defect-free devices are transferred.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If transfer speed is improved by using self-assembly method, then productivity increases, but transfer error rate increases and yield decreases

Engineering Contradiction:

Improvetransfer speedVSAvoidtransfer yield

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces a transfer substrate as an intermediary carrier between the source and destination substrates. The micro-LEDs are first self-assembled onto the transfer substrate with controlled electrode patterns, then transferred to the destination substrate. This intermediary approach allows for better control of the self-assembly process and reduces transfer errors, simultaneously improving both transfer speed and yield.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality by designing specific electrode patterns (source electrodes, assembly electrodes, and pad electrodes) in different regions of the transfer substrate. The electrodes are selectively positioned and configured to control the self-assembly process locally, ensuring accurate micro-LED placement while maintaining high transfer speed and yield.

Inventive Principle:

Principle #3Local quality

2Reliability

If transfer yield is improved by lowering transfer defect rate, then reliability increases, but transfer speed decreases

Engineering Contradiction:

Improvetransfer yieldVSAvoidtransfer speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary actions by pre-configuring the electrode patterns on the transfer substrate before the self-assembly process. The source electrodes, assembly electrodes, and pad electrodes are pre-positioned to guide the micro-LEDs to their correct locations during self-assembly. This preliminary preparation ensures high transfer yield without requiring slow, step-by-step verification, thus maintaining high transfer speed.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If assembly substrate contacts O-ring of bath for self-assembly, then self-assembly process is enabled, but electrodes on assembly substrate are damaged due to frictional force

Engineering Contradiction:

Improveself-assembly capabilityVSAvoidelectrode damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the problematic frictional contact between the assembly substrate and the O-ring by redesigning the substrate structure. The assembly substrate is separated into a transfer substrate with electrodes and a separate support structure. The electrodes are positioned such that they do not directly contact the O-ring during the self-assembly process, eliminating the frictional damage while preserving the self-assembly capability.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Simultaneously improves transfer speed and yield by ensuring only fully assembled and functional devices are transferred, minimizing defects and enabling high-speed, high-yield assembly.

Implementation Method 1

an adhesive film disposed between the roller rotating part and the assembly substrate

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a penetration electrode penetrating the assembly substrate and adhesive film

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12538736B2Electrode structure of roller unit for transferring semiconductor light-emitting element and intelligent integrated assembling and transferring device comprising same

Publication Date: 2026.01.27 LG ELECTRONICS INC

AI summary

Embodiments relate to an electrode structure of a transfer roller part of a semiconductor light emitting device and an intelligent assembly-transfer integration device including the same. Electrode structure of transfer roller part of semiconductor light emitting device according to an embodiment can include a roller rotating part, an assembly substrate mounted on the roller rotating part, an adhesive film disposed between the roller rotating part and the assembly substrate, penetration electrodes penetrating the assembly substrate and roller pad electrodes disposed on the roller rotating part and electrically connected to the penetration electrodes.