Liquid Metal Paste for Flexible Wiring

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Solution Overview

Problem

Conventional metal materials used in electronic devices, such as copper, gold, and silver, are mechanically stiff, making it difficult to apply them to flexible, foldable, or stretchable devices that require deformable and self-healing electrical wiring with high conductivity.

Innovation Solution

A conductive paste material comprising a high content of liquid metal particles, such as gallium or its alloys, combined with a polymer binder and nanofillers like carbon nanotubes, which allows for mechanical deformation and self-healing properties, maintaining electrical conductivity even when damaged.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional metal materials (copper, gold, silver) are used for wiring, then high electrical conductivity is achieved, but mechanical flexibility and deformability are lost

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmechanical flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent uses a composite material consisting of liquid metal particles dispersed in a polymer matrix. This composite structure combines the high electrical conductivity of liquid metal (Ga, Ga-In, Ga-In-Sn, or Ga-In-Sn-Zn alloys) with the mechanical flexibility of the polymer binder, resolving the contradiction between conductivity and flexibility. The liquid metal particles maintain electrical pathways while the polymer matrix provides deformability for flexible and foldable devices.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical state of metal from solid (conventional wiring) to liquid metal particles embedded in polymer. This parameter change allows the material to exhibit both high electrical conductivity (from liquid metal) and mechanical flexibility (from polymer matrix), enabling the wiring to be deformed without breaking while maintaining conductive pathways.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If metal wiring is made flexible through deformation, then adaptability to flexible devices is improved, but self-healing capability and resistance to damage are reduced

Engineering Contradiction:
ImprovedeformabilityVSAvoidself-healing capability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The liquid metal particles inherently possess self-healing capability due to their liquid state. When the wiring is damaged or deformed, the liquid metal can flow and reconfigure to restore electrical pathways without external intervention. This self-service property allows the material to automatically recover from damage, maintaining reliability while providing mechanical flexibility.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent utilizes the fluid nature of liquid metal particles (analogous to hydraulic principles) to enable self-healing. The liquid metal can flow and redistribute within the polymer matrix when damaged, automatically reforming conductive pathways and restoring electrical connectivity without requiring external repair mechanisms.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Adaptability or versatility

If liquid metal particles are used to achieve flexibility, then mechanical deformability is improved, but manufacturing precision and particle dispersion control become more difficult

Engineering Contradiction:
Improvemechanical deformabilityVSAvoidparticle dispersion control
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The polymer binder acts as an intermediary medium that facilitates uniform dispersion of liquid metal particles. The binder provides a matrix that holds the liquid metal particles in place while allowing them to maintain their liquid state, enabling controlled distribution throughout the wiring structure and simplifying manufacturing processes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The polymer matrix functions as a flexible shell that encapsulates and stabilizes the liquid metal particles. This shell structure prevents particle aggregation and ensures uniform dispersion, while the thin film nature of the polymer allows the liquid metal to maintain electrical pathways even when deformed, resolving the manufacturing precision challenge.

Inventive Principle:
Principle #30Flexible shells and thin films

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 paste material enables flexible, foldable, or stretchable electronic devices with high electrical conductivity and self-healing capabilities, reducing resistance changes during deformation and improving the reliability and durability of electrical connections.

Implementation Method 1

liquid metal particles, which may provide self-healing particles for the wiring

Methodology Applied
Scientific EffectLiquid metal self-healing:

Implementation Method 2

a plurality of nanofillers, each having an aspect ratio equal to or greater than 3

Methodology Applied
Scientific EffectNanofiller conduction:

Implementation Method 3

a polymer binder, mixed with the plurality of liquid metal particles

Methodology Applied
Scientific EffectPolymer binding:

Data Source

PatentEP3330327B1Paste material, wiring member formed from the paste material, and electronic device including the wiring member
Publication Date: 2023.07.12 SAMSUNG ELECTRONICS CO LTD
  • EP3330327B1 patent drawingFigure 1
  • EP3330327B1 patent drawingFigure 2A~2B
  • EP3330327B1 patent drawingFigure 2C~3

AI summary

Provided are a paste material, a method of forming the paste material, a wiring member formed from the paste material, and an electronic device including the wiring member. The paste material may include a plurality of liquid metal particles and a polymer binder. The paste material may further include a plurality of nanofillers. At least some of the plurality of nanofillers may each have an aspect ratio equal to or greater than about 3. The content of the plurality of liquid metal particles may be greater than the content of the polymer binder and may be greater than the content of the plurality of nanofillers. The wiring member may be formed by using the paste material, and the wiring member may be used in various electronic devices.