LED Light Extraction via Concavo-Convex Substrate and Thermal Support

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Solution Overview

Problem

Current light emitting devices using III-V nitride semiconductors face challenges in achieving optimal light extraction efficiency and heat dissipation, leading to reduced performance and reliability.

Innovation Solution

The design incorporates a light emitting device structure with a substrate having a concavo-convex pattern, a support member with thermal diffusers, and a reflective electrode layer, along with a flip bonding scheme to enhance light extraction and heat dissipation, utilizing a DBR structure and ceramic materials for improved thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional LED structure with planar substrate and simple electrode configuration is used, then the device complexity is low and ease of manufacture is high, but light extraction efficiency is insufficient and heat dissipation performance is poor

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoiddevice structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The substrate surface is divided into concave and convex regions, creating a non-planar structure that segments the light extraction paths. This segmentation increases the effective light extraction area and reduces total internal reflection, thereby improving light extraction efficiency without requiring complex external optical components

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a two-dimensional planar substrate to a three-dimensional concavo-convex structure. This dimensional change creates additional light extraction interfaces and pathways, enabling improved light extraction efficiency while maintaining structural integrity and manufacturability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If conventional thermal management structures are used, then the device complexity is low, but heat dissipation performance is insufficient leading to reduced reliability

Engineering Contradiction:
Improveheat dissipation performanceVSAvoidthermal management structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The support member integrates multiple functions: mechanical support, thermal conduction, and electrical isolation. By merging these functions into a single component with thermal diffusers, the structure achieves improved heat dissipation while avoiding the complexity of separate thermal management systems

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The support member is constructed as a composite structure combining resin material with thermally conductive particles. This composite approach enhances thermal conductivity for improved heat dissipation while maintaining the electrical isolation properties of the resin matrix, achieving dual functionality without excessive complexity

Inventive Principle:
Principle #40Composite materials

3Temperature

If resin-based support members without thermal enhancement are used, then ease of manufacture is high and device complexity is low, but thermal conductivity is insufficient leading to poor heat dissipation

Engineering Contradiction:
Improvethermal conductivityVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The support member combines resin base material with thermally conductive particles to create a composite structure. This approach significantly enhances thermal conductivity while maintaining the ease of manufacturing associated with resin-based materials, as the particles can be mixed into the resin during the molding process

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention modifies the thermal conductivity parameter of the support member by incorporating thermally conductive particles. This parameter change improves heat dissipation performance while the manufacturing process remains relatively simple, as it involves mixing particles into the resin and curing, which are standard procedures

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

This configuration significantly improves light extraction efficiency and heat dissipation, resulting in enhanced performance and reliability of the light emitting device.

Implementation Method 1

a support member with thermal diffusers

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a reflective electrode layer

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

utilizing a DBR structure

Methodology Applied
Scientific EffectDistributed Bragg reflection: Reflection

Implementation Method 4

ceramic materials for improved thermal conductivity

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2528120B1Light emitting device and light emitting apparatus having the same
Publication Date: 2018.08.01 LG INNOTEK CO LTD
  • EP2528120B1 patent drawingFigure 1~2
  • EP2528120B1 patent drawingFigure 3~5
  • EP2528120B1 patent drawingFigure 6~8

AI summary

A light emitting device (100) may be provided that includes a substrate (111), a light emitting structure (120), a first electrode (135) under a first semiconductor layer (115), a reflective electrode layer (131) under a second conductive semiconductor layer (119), a second electrode (137) under the reflective electrode layer (131), and a support member (151) under the first semiconductor layer (115) and the reflective electrode layer (131) around the first and second electrodes (135,137). A first connection electrode (141) may be provided under the first electrode (135). At least a part of the first connection electrode (141) is provided in the support member (151). A second connection electrode (143) may be provided under the second electrode (137). At least a part of the second connection electrode (143) may be provided in the support member (151).