LED Chip Heat Dissipation via Relocated Power Terminals

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Solution Overview

Problem

Semiconductor light emitting devices face challenges in achieving high heat dissipation without compromising light extraction efficiency, and they often produce shadows on the light-irradiated surface due to metal wire placement.

Innovation Solution

A semiconductor light emitting device design where a metal layer acts as a power supply terminal, supporting a multilayer epitaxial structure with conductive layers, allowing for efficient heat dissipation and light extraction without shadows, by positioning power supply terminals behind the light extraction surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the LED chip is flip-chip mounted to improve heat dissipation, then heat dissipation is improved, but light extraction efficiency is lowered

Engineering Contradiction:

Improveheat dissipationVSAvoidlight extraction efficiency

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The sapphire substrate is removed from the LED chip structure, extracting the problematic element that caused both handling difficulties and light extraction issues. The patent applies this by completely eliminating the sapphire substrate while maintaining the multilayer epitaxial structure through alternative support methods, thereby improving light extraction efficiency without compromising heat dissipation capabilities

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the conventional electrode configuration by forming the cathode electrode on the upper surface and the anode electrode on the lower surface, opposite to the traditional arrangement. This inversion allows for optimized heat dissipation pathways and improved light extraction while maintaining electrical functionality

Inventive Principle:

Principle #13The other way round (Inversion)

2Use of energy by moving object

If the sapphire substrate is removed to improve light extraction efficiency, then light extraction efficiency is improved, but handling difficulty increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidhandling ease

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent applies preliminary action by forming a support structure and electrode configuration before the sapphire substrate removal process. The multilayer epitaxial structure is prepared with integrated support elements and electrode patterns that provide mechanical stability prior to substrate elimination, ensuring the chip remains handleable throughout manufacturing and assembly

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The metal layer serving as the anode electrode is designed to perform multiple functions: electrical conduction, mechanical support, and heat dissipation. This multi-functionality compensates for the removed sapphire substrate's structural role while maintaining light extraction efficiency

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If metal wires are placed above the light extraction surface to supply power, then power supply is enabled, but shadow is produced on the light-irradiated surface

Engineering Contradiction:

Improvepower supplyVSAvoidshadow production

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent relocates the power supply connection from the upper dimension (above light extraction surface) to the lower dimension (below the light extraction surface). The anode electrode is positioned on the lower surface of the multilayer epitaxial structure, allowing power supply without obstructing the light path and eliminating shadow production on the light-irradiated surface

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design enhances heat dissipation and light extraction efficiency, leading to higher luminous efficiency and longer device lifetime with reduced shadowing from metal wires.

Implementation Method 1

the metal layer... conducts heat generated in the light emitting layer

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

Power is supplied to the LED chip... so that the LED chip emits light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS7956368B2Semiconductor light emitting device, lighting module, lighting apparatus, and manufacturing method of semiconductor light emitting device

Publication Date: 2011.06.07 PANASONIC HOLDINGS CORP

AI summary

An LED bare chip which is one type of a semiconductor light emitting device (2) includes a multilayer epitaxial structure (6) composed of a p-GaN layer (12), an InGaN/GaN MQW light emitting layer (14) and an n-GaN layer (16). A p-electrode (18) is formed on the p-GaN layer (12), and an n-electrode (20) is formed on the n-GaN layer (16). An Au plating layer (4) is formed on the p-electrode (18). The Au plating layer (4) supports the multilayer epitaxial structure (6) and conducts heat generated in the light emitting layer (14). The Au plating layer (4) is electrically divided into two portions by a polyimide member (10). One of the two portions (4A) is connected to the p-electrode (18), to be constituted as an anode power supply terminal, and the other portion (4K) is connected to the n-electrode (20) by a wiring (22), to be constituted as a cathode power supply terminal.