Graphene Oxide Coating for Laser Diode Thermal Resistance Reduction

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Solution Overview

Problem

Semiconductor laser diodes face challenges in heat dissipation due to compressive mounting stresses and inefficient heat removal from the active area to the substrate, particularly with conventional soldering methods and heat spreaders, which limit their performance and lifetime.

Innovation Solution

Deposition of a stable aqueous suspension of graphene oxide on coolers and spacers, with a concentration of 1mg/ml, followed by air drying, to enhance heat dissipation in electronic power devices, specifically laser diodes, utilizing graphene oxide's high thermal conductivity and electrical insulation properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional soldering methods are used to attach semiconductor chips to coolers, then mechanical strength and electrical conductivity are improved, but thermal resistance increases and compressive mounting stresses are generated

Engineering Contradiction:
Improvemechanical strengthVSAvoidthermal resistance
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

A thin film of graphene oxide is introduced as an intermediary layer between the semiconductor chip and the cooler. This intermediary provides both mechanical bonding and superior thermal conduction, while the oxygenated groups in graphene oxide create strong adhesion to both substrates, reducing interfacial thermal resistance compared to conventional soldering.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the material parameter from conventional solder materials to graphene oxide, which has fundamentally different properties - extremely high thermal conductivity combined with flexible adhesion characteristics that reduce mounting stresses while maintaining mechanical strength.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If conventional heat spreaders and aluminium wires are used for heat removal, then device assembly is simplified, but heat dissipation efficiency remains very low

Engineering Contradiction:
Improveassembly simplicityVSAvoidheat dissipation efficiency
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The invention uses graphene oxide, a composite material with unique properties combining high thermal conductivity with flexible application methods. The material can be deposited as a thin film that maintains good thermal contact while being applied through simple processes, achieving both high heat dissipation efficiency and ease of manufacture.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The graphene oxide is applied as a thin film that conformally coats the heat spreader surfaces, creating excellent thermal contact without requiring complex assembly procedures. The thin film nature allows it to adapt to surface irregularities, maximizing heat transfer efficiency.

Inventive Principle:
Principle #30Flexible shells and thin films

3Power

If higher power is delivered to laser diodes, then optical output increases, but heat generation increases causing reduced lifetime and performance degradation

Engineering Contradiction:
Improveoptical powerVSAvoiddevice lifetime
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The invention converts the harmful heat generated by high-power operation into a manageable parameter by implementing multi-path heat dissipation through graphene oxide coatings on both the heat spreader and spacer. This allows the device to operate at higher powers while maintaining junction temperatures that preserve lifetime and performance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 method significantly reduces thermal resistance by up to twice, maintaining the laser diode's light-current and voltage-current characteristics, thereby lowering the active area temperature and enhancing device performance and lifespan.

Implementation Method 1

Graphene oxide contains, in its structure, numerous oxygenated groups, such as hydroxyl, epoxy, carboxyl groups. Their presence prevents the free movement of charges, so it is a good electrical insulator and at the same time a very good heat conductor.

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

deposition to the said electronic power device, and especially to the cooler of the semiconductor laser, a stable aqueous suspension of graphene oxide

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

drying the obtained layer at room temperature in air for a time of 1 to 10 hours

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP2792720B1Method of a thermal resistance reduction in electronic power devices, especially in laser diodes
Publication Date: 2020.04.01 INST TECH MATERIAL ELEKT
  • EP2792720B1 patent drawingFigure 1~2
  • EP2792720B1 patent drawingFigure 3
  • EP2792720B1 patent drawingFigure 4

AI summary

The object of the invention is a method of a thermal resistance reduction in electronic power devices, especially in laser diodes, characterised in that it comprises the steps of: a) deposition to the said electronic power device, and especially to a cooler of the semiconductor laser, a stable aqueous suspension of graphene oxide, in particular at a concentration of 1 mg/ml, b) drying the obtained layer at room temperature in air for a time of 1 to 10 hours.