Micro LED Bonding With Inkjet Adhesive Gap Filling

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Solution Overview

Problem

The challenge in manufacturing display devices with micro light-emitting units is to enhance the robustness between the micro light-emitting units and the substrate to improve fabrication yield and quality.

Innovation Solution

A method is employed where an adhesive material is applied between the chips and the substrate using inkjet printing, filling the spaces and gaps between the light-emitting units, and optionally covering their top surfaces, followed by a curing process to reinforce the bonding strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesive material is applied between chip and substrate, then robustness between micro light-emitting units and substrate is improved, but device complexity increases

Engineering Contradiction:
Improverobustness between micro light-emitting units and substrateVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

An adhesive material is introduced as an intermediary substance between the chip and substrate to enhance bonding strength. The adhesive material fills the gap between these components, creating a stronger mechanical and chemical bond that improves overall device robustness while maintaining a relatively simple application process through inkjet printing technology.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If adhesive material is applied using inkjet printing, then manufacturing precision is improved, but ease of manufacture decreases

Engineering Contradiction:
Improveadhesive material application precisionVSAvoidease of manufacture
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The traditional mechanical application methods for adhesive materials are replaced with inkjet printing technology. This substitution enables precise digital control of adhesive deposition, allowing for accurate placement and dosage control that improves manufacturing precision while the automated printing process ultimately simplifies the overall manufacturing workflow.

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

3Reliability

If adhesive material fills gaps between light-emitting units, then reliability is improved, but loss of substance increases

Engineering Contradiction:
Improvefixation qualityVSAvoidadhesive material consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The adhesive material application is optimized to provide local quality enhancement where needed. The inkjet printing technology enables precise deposition of adhesive material specifically in the gap regions between light-emitting units and chips, rather than uniform application across entire surfaces. This localized approach ensures reliable fixation while minimizing overall adhesive material consumption.

Inventive Principle:
Principle #3Local quality

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 method improves the robustness and quality of micro light-emitting units by enhancing the caulking property of the adhesive material, leading to better fixation and increased yield in display device manufacturing.

Implementation Method 1

an adhesive material is applied to the space between the chip and the substrate

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

followed by a curing process to reinforce the bonding strength

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3974489B1Method of manufacturing display device
Publication Date: 2025.12.03 INNOLUX CORP
  • EP3974489B1 patent drawingFigure 1
  • EP3974489B1 patent drawingFigure 2~3
  • EP3974489B1 patent drawingFigure 4

AI summary

A method of manufacturing a display device (100A, 100B, 100C, 101A, 101B, 101C) includes providing a light emitting unit (121, 122, 123) which has a chip (121C, 122C, 123C) and at least one bonding pin (121A, 122A, 123A), mounting the light emitting unit (121, 122, 123) on the substrate (110) through the at least one bonding pin (121A, 122A, 123A), and applying an adhesive material (130) to a space (121S, 122S, 123S) between the chip (121C, 122C, 123C) and the substrate (110).