Submicron Silver Ink Adhesion via Intermediary Agents

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Solution Overview

Problem

Existing conductive ink compositions face challenges in achieving a balance between adhesion to substrates, stability of submicron silver particles, low-temperature sintering, and electrical conductivity, particularly when applied to non-metallic substrates for use in touch panel displays.

Innovation Solution

The composition includes stabilized submicron silver particles, a thermoplastic resin, and a capping agent, optionally with organic diluents and non-silver conductive fillers, which are applied to non-conductive substrates and sintered at relatively low temperatures to form conductive networks with enhanced adhesion and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If submicron silver particles are used to achieve low resistivity and good electrical conductivity, then electrical conductivity is improved, but adhesion to non-metallic substrates deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidadhesion to substrate
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent employs organic vehicles and coupling agents as intermediary substances between submicron silver particles and non-metallic substrates. These intermediaries improve adhesion by chemically or physically bonding to both the silver particles and the substrate surface, resolving the adhesion problem while maintaining the electrical conductivity benefits of submicron particles.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates composite ink compositions that combine submicron silver particles with organic vehicles, resins, and coupling agents. This composite approach allows the system to simultaneously achieve low resistivity from the silver particles and good adhesion from the composite matrix that bonds to the non-metallic substrate.

Inventive Principle:
Principle #40Composite materials

2Reliability

If submicron silver particles are used to achieve low resistivity, then electrical conductivity is improved, but stability of particles deteriorates due to aggregation

Engineering Contradiction:
Improveelectrical conductivityVSAvoidparticle stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

Coupling agents and surface-modified resins act as intermediaries that prevent direct contact and aggregation between submicron silver particles. These intermediaries maintain particle dispersion and stability in the ink composition while still allowing electrical conductivity through the particle network.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies surface parameters of silver particles through coating or surface treatment to change their interfacial properties. This prevents aggregation by altering surface energy and compatibility with the organic vehicle, maintaining both stability and conductivity.

Inventive Principle:
Principle #35Parameter changes

3Strength

If conventional ink compositions are used to achieve good adhesion, then adhesion is improved, but sintering temperature increases

Engineering Contradiction:
Improveadhesion to substrateVSAvoidsintering temperature
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The invention changes the chemical composition parameters of the organic vehicle and binder system to enable low-temperature sintering. By selecting specific resins and additives with appropriate glass transition temperatures and bonding characteristics, adhesion is achieved without requiring high sintering temperatures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs organic vehicles and binders that are designed to be removed or decomposed at relatively low temperatures during the sintering process. These temporary supporting materials enable adhesion during application but are eliminated at low temperatures, avoiding the need for high-temperature processing.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 solution achieves good adhesion and low resistivity in conductive networks, with resistivity as low as 1x10^-5 Ohms.cm, and maintains adhesion comparable to ASTM level 5B, making it suitable for touch panel displays and other applications.

Implementation Method 1

stabilized submicron silver particles... one or more capping agent

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

methods for adhering submicron silver particles to a non-metallic substrate

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

sintered at relatively low temperatures to form conductive networks

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3033401B1Submicron silver particle ink compositions, process and applications
Publication Date: 2019.06.05 HENKEL IP & HOLDING GMBH

AI summary

Provided herein are conductive ink compositions having a good balance between adhesion to substrate, stability of submicron- sized particles, the ability to be sintered at relatively low temperatures, and good electrical conductivity. In one aspect, there are provided conductive networks prepared from compositions according to the present invention. In certain aspects, such conductive networks are suitable for use in touch panel displays. In certain aspects, the invention relates to methods for adhering submicron silver particles to a non-metallic substrate. In certain aspects, the invention relates to methods for improving the adhesion of a submicron silver-filled composition to a non-metalic substrate.