Composite Bonding Layer for LED Yield

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Solution Overview

Problem

Existing display devices are not cost-effective and do not have a high yield in manufacturing light-emitting diodes, which limits their economic benefits and performance.

Innovation Solution

A display device with a bonding layer of high melting point is formed by combining a first material layer with a low melting point and a second material layer, where the second material layer diffuses into the first layer during a heating and compression process, creating a bonding layer with improved thermal stability and preventing electrical connections from being damaged during subsequent processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a low melting point bonding layer is used to attach the light-emitting unit to the substrate, then the manufacturing process is simplified and costs are reduced, but the electrical connections are damaged during subsequent high-temperature processes

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidelectrical connection integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The bonding layer is formed as a composite structure with a first material layer (low melting point) and a second material layer (high melting point). The low melting point material enables simple attachment processes, while the high melting point material provides thermal stability during subsequent high-temperature steps, resolving the contradiction between ease of manufacture and reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The bonding layer's melting point parameter is changed from uniform low melting point to a layered structure with different melting points. The first material layer has low melting point for easy bonding, while the second material layer has high melting point for thermal stability, allowing the system to satisfy both manufacturing simplicity and connection integrity requirements.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a high melting point bonding layer is used to prevent damage during high-temperature processes, then reliability is improved, but manufacturing complexity and costs increase

Engineering Contradiction:
Improveelectrical connection integrityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The bonding layer combines two materials with complementary properties: low melting point material for easy processing and high melting point material for thermal stability. This composite approach achieves reliability without requiring the entire bonding layer to have high melting point, thus avoiding excessive manufacturing complexity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

Different regions of the bonding layer have different melting point properties tailored to their specific functions. The first material layer region provides low melting point for attachment simplicity, while the second material layer region provides high melting point for high-temperature process stability, optimizing both manufacturing ease and reliability locally.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If traditional bonding methods are used to attach the light-emitting unit, then manufacturing costs are reduced, but the yield of manufacturing is low due to damage to light-emitting units

Engineering Contradiction:
Improvemanufacturing costVSAvoidmanufacturing yield
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The layered bonding structure with different melting points allows the attachment process to be performed at lower temperatures (simplifying manufacturing), while the high melting point second layer protects against damage during subsequent high-temperature processes, thereby improving both ease of manufacture and manufacturing yield.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The high melting point second material layer is prepared in advance as a protective barrier before subsequent high-temperature manufacturing steps. This pre-positioned protective layer prevents damage to the light-emitting unit during later processing, improving yield without adding significant manufacturing complexity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 formation of a high melting point bonding layer enhances the yield and reduces manufacturing costs by preventing damage to the light-emitting unit and simplifying the manufacturing process, leading to improved performance and cost-effectiveness.

Implementation Method 1

the second material layer diffuses into the first layer during a heating and compression process

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

the second material layer diffuses into the first layer during a heating and compression process

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

the second material layer diffuses into the first layer during a heating and compression process

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3382754B1Display device
Publication Date: 2021.06.30 INNOLUX CORP
  • EP3382754B1 patent drawingFigure 1A
  • EP3382754B1 patent drawingFigure 1B
  • EP3382754B1 patent drawingFigure 1C

AI summary

A display device is provided. The display device includes a light-emitting unit. The light-emitting unit includes a light-emitting part, wherein a light extraction structure is disposed on a first surface of the light-emitting part. The light-emitting unit also includes a connective part disposed on a second surface opposite to the first surface of the light-emitting part. The light-emitting unit further includes a protective part surrounding the light-emitting part and the connective part. In addition, the display device includes a substrate having a plurality of active elements and at least one bonding pad, wherein the bonding pad is electrically connected to the corresponding connective part of the light-emitting unit. The roughness of the light extraction structure is greater than or equal to 0.2µm and less than or equal to 5µm.