Liquid Metal Flexible Interconnects for Fatigue-Resistant Conductivity

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Solution Overview

Problem

Solid metal traces in flexible interconnects fatigue over time due to repeated flexing, leading to breakage and disruption of electrical connections in moveable electronic devices.

Innovation Solution

Incorporation of liquid metal conductors in flexible interconnects, which can flow to maintain conductivity even when solid metal traces break, combined with an encapsulating layer to retain the liquid metal in place and prevent undesired alloying.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solid metal traces are used in flexible interconnects, then electrical conductivity is maintained, but the traces fatigue and breakage occurs over time due to repeated flexing

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidservice life of metal traces

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the physical state of the conductor from solid to liquid. The liquid metal conductor (e.g., gallium-based alloy) remains liquid at operating temperatures and can flow to maintain electrical continuity even when the flexible substrate is bent or deformed, eliminating fatigue-related breakage that plagues solid metal traces

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure combining a flexible polymer substrate with liquid metal conductor. This composite approach allows the interconnect to maintain flexibility while providing reliable electrical conduction, as the liquid metal fills voids and maintains contact paths that solid traces cannot sustain under repeated deformation

Inventive Principle:

Principle #40Composite materials

2Reliability

If liquid metal is used to replace solid metal traces, then fatigue resistance is improved, but the liquid metal may diffuse and alloy with surrounding materials

Engineering Contradiction:

Improvefatigue resistanceVSAvoiddiffusion and chemical reaction

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a barrier layer as an intermediary between the liquid metal conductor and the flexible substrate or other materials. This barrier layer (e.g., oxide layer, polymer coating, or metal oxide) prevents direct contact between the liquid metal and surrounding materials, thereby preventing diffusion and unwanted alloying reactions while allowing the liquid metal to maintain its electrical function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies a protective coating or barrier layer to the flexible substrate before introducing the liquid metal, or forms an oxide layer on the liquid metal surface, to preemptively prevent harmful diffusion and chemical reactions. This preliminary protective measure stops the harmful interaction before it can occur

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If liquid metal is used in flexible interconnects, then conductivity is maintained under deformation, but the liquid metal requires encapsulation to retain it in place

Engineering Contradiction:

Improveconductivity under flexingVSAvoidencapsulation structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a flexible polymer substrate and thin film encapsulation layers to contain the liquid metal conductor. These flexible shells and thin films conform to the bending and deformation of the interconnect, maintaining encapsulation integrity while allowing the liquid metal to flow and maintain electrical paths under stress

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 use of liquid metal conductors enhances the durability and reliability of electrical connections by preventing circuit breakage from fatigue and maintaining conductivity in flexible interconnects, even under high-angle bending and deformation.

Implementation Method 1

Incorporation of liquid metal conductors in flexible interconnects, which can flow to maintain conductivity even when solid metal traces break

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

combined with an encapsulating layer to retain the liquid metal in place and prevent undesired alloying

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP3473064B1Flexible interconnect

Publication Date: 2026.01.21 MICROSOFT TECHNOLOGY LICENSING LLC

Figure 1A~1B
Figure 1C
Figure 2

AI summary

Examples are provided for a flexible circuit element including a flexible insulating support structure, a solid metal trace extending at least partially between a first connector and a second connector on the flexible insulating support structure, and a liquid metal conductor disposed in contact with the solid metal trace in a region of the trace configured to repeatedly flex when installed in a device.