Metal Nanoparticle Thermal Interface for High-Power Electronics

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Solution Overview

Problem

Current thermal interface materials, such as AuSn solder, are inadequate for high-power electronic components like MMICs and LEDs due to issues like void formation, mechanical failure, and thermal stability limitations, leading to inefficient heat dissipation and increased costs.

Innovation Solution

A metallic thermal interface layer formed from partially fused metal nanoparticles, particularly copper nanoparticles, which provides high thermal conductivity and compatibility with high-power electronic components, reducing void formation and CTE mismatch, and can be applied using simpler methods compared to traditional solders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If AuSn solder is used for thermal interface, then thermal conductivity is improved, but void formation and mechanical failure occur

Engineering Contradiction:
Improvethermal conductivityVSAvoidmechanical failure
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent changes the material parameters by using copper nanoparticles instead of traditional AuSn solder. The nanoparticle form factor and material composition are fundamentally altered to achieve both high thermal conductivity and reliability. The copper nanoparticles can be densely packed to eliminate voids while maintaining excellent thermal properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures by combining copper nanoparticles with other materials to create a thermal interface material that achieves both high thermal conductivity and mechanical reliability. The composite nature allows optimization of both thermal performance and structural integrity.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If thermal epoxies are used for thermal interface, then ease of application is improved, but temperature stability deteriorates

Engineering Contradiction:
Improveease of applicationVSAvoidtemperature stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent changes the material from organic thermal epoxies to inorganic copper nanoparticles, fundamentally altering the temperature stability parameter. The copper nanoparticles can withstand much higher temperatures without degradation, while still maintaining ease of application through various deposition techniques.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If Cu alloy substrates are used to match CTE, then CTE mismatch is reduced, but passivating oxide layer formation increases

Engineering Contradiction:
ImproveCTE matchingVSAvoidoxide layer formation
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts or removes the passivating oxide layer through chemical etching processes, allowing the copper nanoparticles to directly contact and bond with the substrate surface. This eliminates the harmful oxide barrier while maintaining the CTE-matching benefits of copper alloy substrates.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary chemical etching to remove the oxide layer before applying the copper nanoparticle thermal interface material. This preliminary action prepares the surface for optimal bonding and thermal contact, preventing oxide-related issues during operation.

Inventive Principle:
Principle #10Preliminary action

4Temperature

If AuSn solder is used for high-power devices, then thermal conductivity is improved, but processing complexity and cost increase

Engineering Contradiction:
Improvethermal conductivityVSAvoidprocessing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent changes multiple parameters simultaneously: material composition (copper instead of AuSn), particle size (nanoscale), and application method (various deposition techniques instead of complex soldering). These parameter changes collectively reduce processing complexity while maintaining or improving thermal conductivity.

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

The use of metal nanoparticle-based thermal interfaces enhances heat transfer efficiency, increases the operational reliability of high-power devices, and reduces manufacturing costs by eliminating the need for costly and complex processing techniques.

Implementation Method 1

heating the composition above a fusion temperature of the metal nanoparticles to melt the metal nanoparticles and fuse the metal nanoparticles together

Methodology Applied
Scientific EffectFusion: Melting

Implementation Method 2

The metallic thermal interface layer is formed from a composition comprising a plurality of metal nanoparticles that are at least partially fused together with one another

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3036764B1High-power electronic devices containing metal nanoparticle-based thermal interface materials and related methods
Publication Date: 2018.06.27 LOCKHEED MARTIN CORP
  • EP3036764B1 patent drawingFigure 1A~1B
  • EP3036764B1 patent drawingFigure 2
  • EP3036764B1 patent drawingFigure 3

AI summary

High-power electronic components generate significant amounts of heat that must be removed in the course of normal device operations. Certain types of electronic components, such as some monolithic microwave integrated circuits and LEDs, can contain materials that are difficult to effectively bond to a heat sink in order to establish a thermal interface between the two. Device assemblies can include a heat-generating electronic component in thermal communication with a metallic heat sink via a metallic thermal interface layer. The metallic thermal interface layer is disposed between the heat-generating electronic component and the metallic heat sink. The metallic thermal interface layer is formed from a composition including a plurality of metal nanoparticles that are at least partially fused together with one another. Methods for forming a thermal interface layer include heating metal nanoparticles above their fusion temperature and subsequently cooling the liquefied metal nanoparticles to promote bonding of the electronic component.