Aluminum Nitride Co-fired Substrate LED Heat Management

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Solution Overview

Problem

Conventional light emitting apparatuses suffer from poor heat radiation performance, limited current capacity, complex manufacturing processes, and reduced luminance due to the use of ceramic substrates with low thermal conductivity and brittle materials, leading to increased light loss and size issues.

Innovation Solution

A light emitting apparatus utilizing an aluminum nitride co-fired substrate with high thermal conductivity, a reflector with an inclined metal or resin surface for improved light reflection, and a flip-chip mounting method to enhance heat dissipation and light extraction, eliminating the need for wire bonding and allowing for compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ceramic package with alumina is used for mounting LED chip, then manufacturing process is simplified, but heat radiation performance becomes poor

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidheat radiation performance

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent changes the thermal conductivity parameter of the substrate material from low (alumina ceramic at 15-20 W/mK) to high (aluminum nitride co-fired substrate at over 170 W/mK). This material substitution maintains manufacturing feasibility while dramatically improving heat radiation performance, allowing the LED to operate at higher currents for increased luminance.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional ceramic package is used, then device structure is simple, but current capacity is limited to several tens of mA

Engineering Contradiction:

Improvedevice structure simplicityVSAvoidcurrent capacity

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent employs a composite structure combining aluminum nitride co-fired substrate with high thermal conductivity, reflector with high reflectivity, and LED chip. This composite approach enables the device to handle several amperes of current while maintaining structural simplicity and achieving high luminance through improved heat management.

Inventive Principle:

Principle #40Composite materials

3Reliability

If molding resin is used for sealing LED chip, then sealing is achieved, but thermal conductivity remains low

Engineering Contradiction:

Improvesealing performanceVSAvoidthermal conductivity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent introduces a heat sink as an intermediary thermal management component. The heat sink is bonded to the aluminum nitride substrate, creating a thermal conduction path that bypasses the low thermal conductivity molding resin. This intermediary structure maintains reliable sealing while enabling efficient heat extraction from the LED chip.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If LED chip is mounted with wire bonding, then electrical connection is achieved, but light loss increases and size increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidlight loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts and eliminates the wire bonding process from the conventional LED mounting structure. By using the aluminum nitride co-fired substrate with integrated electrical connections and a reflector structure, the invention removes the wire bonding component that caused light loss and increased device size, achieving both electrical connection and reduced optical losses.

Inventive Principle:

Principle #2Taking out (Extraction)

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 significantly increases heat radiation performance, allows higher current flow, and enhances luminance with improved light extraction efficiency, enabling a more efficient and compact light emitting apparatus.

Implementation Method 1

an aluminum nitride co-fired substrate; at least one light emitting devices mounted on a front surface of the co-fired substrate

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a reflector (light reflecting body) having an inclined surface for reflecting a light emitted from the light emitting devices to a front side direction

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS7812360B2Light emitting device, lighting equipment or liquid crystal display device using such light emitting device

Publication Date: 2010.10.12 NITERRA MATERIALS CO LTD

AI summary

A light emitting apparatus 11 comprises: an aluminum nitride co-fired substrate 13; at least one light emitting device 15 mounted on a front surface of the co-fired substrate 13 through a flip-tip method; and a reflector 16 having an inclined surface 14 for reflecting a light emitted from the light emitting device 15 to a front side direction, the reflector 16 is bonded to a surface of the aluminum nitride co-fired substrate 13 so as to surround a circumference of the light emitting device 15. This configuration can simplify the process of manufacturing the apparatus and can provide light emitting apparatus that are excellent in heat radiation performance, allow a larger current to pass therethrough, and can have a significantly increased luminance with a high luminous efficiency.