Encapsulation Substrate Warpage Prevention in Display Apparatus

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Solution Overview

Problem

Display apparatuses with high thermal conductivity encapsulation substrates face warpage issues due to thermal expansion, leading to reduced lifetime and deterioration of light-emitting devices.

Innovation Solution

Incorporating a moisture-blocking layer with a lower water vapor transmission rate between the encapsulating layer and the encapsulation substrate, along with penetrating holes in the encapsulation substrate, to prevent warpage and moisture ingress, while maintaining heat radiation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If an encapsulation substrate with high thermal conductivity (such as metal) is used, then heat radiation efficiency is improved, but thermal expansion causes warpage of the encapsulation substrate

Engineering Contradiction:

Improveheat radiation efficiencyVSAvoidwarpage of encapsulation substrate

Core Design Contradiction:

TemperatureVSShape

Solution Approach 1:

The encapsulation substrate includes a plurality of penetrating holes, creating a porous structure that reduces the overall thermal mass and thermal expansion of the substrate while maintaining high thermal conductivity pathways, thereby preventing warpage caused by thermal expansion

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The encapsulation substrate is formed by combining metal particles (for thermal conductivity) with a resin matrix (for structural stability), creating a composite material that balances heat radiation efficiency with resistance to thermal expansion-induced warpage

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If the encapsulation substrate is made of material with high thermal conductivity, then heat dissipation is improved, but the light-emitting device deteriorates due to warpage

Engineering Contradiction:

Improveheat dissipationVSAvoiddeterioration of light-emitting device

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The penetrating holes in the encapsulation substrate reduce thermal mass and expansion while preserving heat dissipation pathways, preventing warpage that would otherwise cause deterioration of the light-emitting device

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

A moisture-blocking layer is introduced as an intermediary between the encapsulating layer and the encapsulation substrate, preventing moisture ingress through the penetrating holes and protecting the light-emitting device from deterioration while maintaining heat dissipation functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

3Shape

If penetrating holes are added to the encapsulation substrate, then warpage is prevented, but moisture may ingress through the holes

Engineering Contradiction:

Improveprevention of warpageVSAvoidmoisture ingress

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

A moisture-blocking layer is positioned between the encapsulating layer and the encapsulation substrate, serving as an intermediary that blocks moisture ingress through the penetrating holes while allowing the holes to function for preventing warpage

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The moisture-blocking layer is selectively positioned at the penetrating holes of the encapsulation substrate, providing localized moisture protection exactly where the penetrating holes create potential ingress paths, while maintaining the overall warpage prevention functionality

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 effectively minimizes the deterioration of light-emitting devices and prevents warpage of the encapsulation substrate, thereby enhancing the display apparatus's lifetime and performance.

Implementation Method 1

A first moisture-blocking layer is disposed between the encapsulating layer and the encapsulation substrate. The water vapor transmission rate of the first moisture-blocking layer is lower than the water vapor transmission rate of the encapsulating layer.

Methodology Applied

Scientific EffectWater vapor transmission blocking: Permeation

Implementation Method 2

The encapsulation substrate may include a material having a relatively high thermal conductivity, such as metal.

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

since the material having a relatively high thermal conductivity may have high thermal expansion coefficient, the encapsulation substrate of the display apparatus may be warped due to the thermal expansion by the heat applied in a forming process or the external heat.

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11121347B2Display apparatus having an encapsulation substrate of high thermal conductivity

Publication Date: 2021.09.14 LG DISPLAY CO LTD

AI summary

A display apparatus comprises a light-emitting device on a device substrate; an encapsulating layer on the device substrate and covering the light-emitting device; an encapsulation substrate on the encapsulating layer and including a plurality of penetrating holes disposed at a regular interval; and a moisture-blocking layer between the encapsulating layer and the encapsulation substrate and including a plurality of moisture-absorbing particles dispersed in the encapsulating layer, wherein the moisture-blocking layer has a water vapor transmission rate lower than that of the encapsulating layer.