Reactive Metal Ink for Printed Electronics
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Solution Overview
Problem
Conductive inks used in printed electronic circuits, such as silver inks, have limited current carrying capacity and are prone to degradation due to electromigration, leading to short circuit lifetimes, which restricts their application in high-current density environments.
Innovation Solution
Development of a reactively assisted ink that includes particles of a first metal with high diffusivity, which undergo a chemical reaction with a substance to produce a product with lower diffusivity, resulting in an electrically conductive material with improved thermal and electrical stability, capable of handling high current densities without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver particles are used in conductive ink, then electrical conductivity is improved, but current carrying capacity is limited due to electromigration
Solution Approach 1:
The patent changes the material parameter of the conductive particles from pure silver to reactive metal particles (such as aluminum) that undergo chemical transformation. This parameter change enables the particles to form intermetallic compounds with lower diffusivity, thereby increasing current carrying capacity and circuit longevity while maintaining electrical conductivity.
Solution Approach 2:
The patent utilizes phase transition through chemical reaction, where reactive metal particles transform into intermetallic compounds or solid solutions upon contact with moisture or oxygen. This phase transition from reactive metal to stable compound reduces atomic diffusivity and electromigration, solving the reliability and longevity contradiction.
2Reliability
If high temperature sintering is used to fuse particles, then electrical connections are improved, but substrate compatibility is reduced
Solution Approach 1:
The patent replaces the mechanical/thermal sintering system with a chemical reaction system. Instead of using high temperature to fuse particles physically, the reactive metal particles undergo chemical reactions to form bonds, achieving reliable electrical connections at lower temperatures compatible with various substrates including flexible polymers.
Solution Approach 2:
The reactive metal particles self-react with environmental moisture or oxygen to form stable intermetallic compounds, eliminating the need for external high-temperature sintering equipment. This self-service mechanism enables low-temperature processing that preserves substrate integrity across different material types.
3Reliability
If conventional silver ink is used, then electrical conductivity is achieved, but degradation occurs due to electromigration at high current densities
Solution Approach 1:
The patent creates a composite material system where reactive metal particles (aluminum) form intermetallic compounds with other elements upon reaction. This composite structure exhibits superior electrical stability and resistance to electromigration compared to pure silver, extending circuit lifespan while maintaining conductivity.
Solution Approach 2:
The patent converts the naturally occurring reaction between reactive metals and environmental moisture/oxygen from a potential degradation mechanism into a beneficial process. This reaction forms stable intermetallic compounds with low diffusivity that resist electromigration, transforming what could be a harmful oxidation process into a protective mechanism that enhances circuit durability.
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 reactively assisted ink forms conductive lines or areas with enhanced stability and durability, capable of withstanding high current densities for extended periods, surpassing the limitations of conventional inks by decoupling the sintering mechanism from the degradation process.
Implementation Method 1
At least some of the particles include a substance with which the first metal is chemically reactive to produce a product during a chemical reaction
Implementation Method 2
Once deposited on a substrate, the particles should be sintered, i.e., fused into a solid mass, to provide electrical and mechanical connections between the particles
Implementation Method 3
the first metal is chemically reactive to produce intermetallic compounds or solid solutions with lower electromigration propensity
Data Source
AI summary
An ink contains particles containing metal that reacts during sintering to produce an electrically conductive line or area having a diffusivity that is less than the diffusivity of the metal before the reaction. Resulting electronic circuits therefore exhibit longer useful lives, compared to conventionally inkjet printed circuits.