Micro-LED Electrode Bonding With Conductive Balls and Adhesive

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing display technologies face challenges in achieving precise electrical connection between micro-scale or millimeter-scale semiconductor light emitting elements and wiring electrodes due to issues with bonding methods, such as randomness of conductive ball positions, high pressure requirements, and limited bondable areas, which are exacerbated by the need for high-resolution and large-area displays.

Innovation Solution

A display device using semiconductor light emitting elements with a wiring substrate, first electrodes, conductive balls, and conductive adhesive parts, including conductive nanoparticles, to facilitate electrical connection under relaxed bonding conditions, reducing the need for excessive pressure and improving productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive balls are used for bonding light emitting elements to wiring electrodes, then electrical connection is achieved, but the positions of conductive balls are random causing potential electrical connection of small element pads

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidconductive ball position precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A non-conductive adhesive paste is introduced as an intermediary material between the conductive balls and the bonding surfaces. This adhesive paste fixes the conductive balls at precise positions, preventing the randomness issue while maintaining electrical connection functionality. The adhesive acts as a mediator that holds the conductive balls in place during and after the bonding process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If a polymer resin adhesive is used for bonding, then bonding is achieved, but high pressure is required due to resin flow and resistance

Engineering Contradiction:

Improvebonding strengthVSAvoidbonding pressure

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The invention changes the physical and chemical parameters of the adhesive material by using a non-conductive paste with specific rheological properties instead of a polymer resin. This paste formulation allows for lower bonding pressure while achieving adequate adhesion, reducing the force requirement during the bonding process.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If fixed position conductive balls are used in thin ACF, then bonding precision is improved, but manufacturing difficulty increases and material costs rise for large-area displays

Engineering Contradiction:

Improveconductive ball position precisionVSAvoidmanufacturing ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention uses a disposable non-conductive adhesive paste that is applied fresh for each bonding operation. This approach replaces the need for expensive, precisely manufactured thin ACF with fixed conductive balls, achieving similar positioning precision through a simpler, more cost-effective adhesive-based method suitable for large-area displays.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Area of stationary object

If bonding is performed with limited bondable area due to bonding head flatness, then localized bonding is achieved, but excessive or weak pressure is applied depending on bonding head flatness and horizontality

Engineering Contradiction:

Improvebondable areaVSAvoidbonding pressure uniformity

Core Design Contradiction:

Area of stationary objectVSForce

Solution Approach 1:

The invention changes the bonding approach by using a paste-based adhesive system that can accommodate variations in bonding head flatness and horizontality. The paste's flow properties allow it to distribute more uniformly across the bonding interface, reducing the impact of pressure variations and achieving more consistent bonding results across different areas.

Inventive Principle:

Principle #35Parameter changes

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 solution enables reliable electrical connection between light emitting elements and wiring electrodes with increased contact area and reduced bonding pressure, allowing for high-resolution and large-area displays with improved manufacturing efficiency and reduced material costs.

Implementation Method 1

conductive adhesives parts located on the conductive balls to fix the conductive balls to at least one of the first electrodes or the first-type electrodes

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250366296A1Display device using light-emitting element and manufacturing method therefor

Publication Date: 2025.11.27 LG ELECTRONICS INC

AI summary

The present disclosure can be applied to technical fields relating to display devices, and relates to a display device using, for example, a micro light-emitting diode (LED) and a manufacturing method therefor. The present disclosure, which is a display device using a semiconductor light-emitting element, may comprise: a wiring substrate; first electrodes defining unit sub-pixel regions and arranged on the wiring substrate; light-emitting elements having first type electrodes disposed on the first electrodes; a plurality of conductive balls electrically connecting the first type electrodes of the light-emitting elements with the first electrodes; and conductive adhesive parts located on the conductive balls to fix the conductive balls to the first electrodes and/or to the first type electrodes.