Conductive Adhesive Layer for OELD Moisture Protection

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Solution Overview

Problem

Organic electroluminescent display devices (OELDs) face issues with moisture intrusion between substrates, leading to display quality and production efficiency problems, particularly due to incomplete coverage by passivation or metal layers and non-uniform spacer thickness, which results in contact defects and reduced lifespan.

Innovation Solution

An OELD device with an adhesive layer made of a conductive material, including inorganic and organic compound particles, fills the space between substrates, providing stable electrical connections and preventing moisture permeation, while ensuring uniform thickness and robust attachment of substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If passivation or metal layers are used to prevent moisture intrusion, then moisture protection is improved, but coverage is incomplete leading to contact defects

Engineering Contradiction:
Improvemoisture protectionVSAvoidcoverage uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses a composite adhesive layer combining inorganic compound particles (for moisture barrier properties) and organic compound particles (for adhesion and filling properties). This composite structure provides both moisture protection and complete coverage, resolving the contradiction between moisture protection and coverage uniformity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The adhesive layer acts as an intermediary substance that fills the space between substrates and provides both mechanical attachment and moisture barrier functions. It mediates between the structural requirements and the moisture protection requirements, ensuring complete coverage while preventing moisture intrusion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If spacers are used to maintain substrate distance, then structural stability is improved, but non-uniform thickness causes contact defects

Engineering Contradiction:
Improvesubstrate spacing stabilityVSAvoidthickness uniformity
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent changes the physical parameters of the adhesive layer (viscosity, particle size distribution, composition ratio) to achieve self-leveling properties. By optimizing these parameters, the adhesive layer maintains uniform thickness even when filling irregular spaces between substrates, resolving the contradiction between spacing stability and thickness uniformity.

Inventive Principle:
Principle #35Parameter changes

3Strength

If adhesive material is used to fill space between substrates, then substrate attachment is improved, but moisture intrusion still occurs reducing lifespan

Engineering Contradiction:
Improvesubstrate attachmentVSAvoidmoisture resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The adhesive layer is formulated as a composite material containing inorganic compound particles (such as氧化铝, SiO2) that provide moisture barrier properties while organic compound particles provide adhesion. This composite structure simultaneously achieves strong substrate attachment and effective moisture resistance, resolving the contradiction between attachment strength and moisture resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The adhesive layer has non-uniform composition at the microscopic level, with inorganic particles concentrated in regions requiring moisture barrier properties and organic particles providing adhesion at substrate interfaces. This local differentiation of material properties allows the single layer to fulfill multiple conflicting functions.

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

The solution enhances display quality and production efficiency by preventing moisture intrusion, ensuring stable electrical connections, and extending the device's lifespan, even in larger sizes, by using an adhesive layer with specific conductivity and viscosity properties.

Implementation Method 1

preventing moisture permeation

Methodology Applied
Scientific EffectPermeation resistance: Permeation

Implementation Method 2

providing stable electrical connections

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2190021B1Organic electroluminescent display device
Publication Date: 2019.02.13 LG DISPLAY CO LTD
  • EP2190021B1 patent drawingFigure 1
  • EP2190021B1 patent drawingFigure 2A~2B
  • EP2190021B1 patent drawingFigure 3

AI summary

A an organic electroluminescent display device includes an array substrate (105) including a driving thin film transistor in a pixel region on a first substrate; an opposing substrate (110) including an organic electroluminescent diode in the pixel region on a second substrate; an adhesive layer (120) filling a space between the array substrate and the opposing substrate; and a connection spacer (150) to electrically connect the organic electroluminescent diode with the driving thin film transistor.