Conductive Ink Deposition on Porous Substrates Without Heat Sintering

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Solution Overview

Problem

Existing methods for producing electrically conductive members using metal fine particles require high-temperature sintering, which limits their application to low-heat resistant substrates and flexible substrates, and results in insufficient bending resistance and electrical conductivity.

Innovation Solution

A method involving the application of an electrically conductive ink containing a metal fine particle dispersion to a substrate with a porous surface, where the metal fine particles are dispersed with a polymer having a glass transition temperature not higher than the formation temperature of the electrically conductive images, allowing necking between the metal fine particles to occur at ordinary temperatures and enhancing bending resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-temperature sintering is used to form electrically conductive images with metal fine particles, then electrical conductivity is improved, but the method cannot be applied to low-heat resistant substrates and flexible substrates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidsubstrate compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the temperature parameter from high-temperature sintering to ordinary-temperature processing by using a polymer dispersant with low glass transition temperature. This allows metal fine particles to be dispersed and bonded on heat-sensitive substrates without requiring high-temperature treatment, thereby expanding substrate compatibility while maintaining electrical conductivity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a polymer dispersant as an intermediary substance between metal fine particles and the substrate. This polymer acts as a bonding agent that enables particle adhesion and electrical connection at ordinary temperatures, replacing the need for high-temperature sintering and enabling application on flexible and heat-sensitive substrates.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional high-temperature sintering is applied, then electrical conductivity is achieved, but bending resistance is insufficient

Engineering Contradiction:
Improveelectrical conductivityVSAvoidbending resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The polymer dispersant serves as a flexible intermediary that bonds metal fine particles together and to the substrate. This polymer matrix provides mechanical flexibility and bending resistance while maintaining electrical conductivity through the metal particle network, solving both conductivity and durability requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite structure consisting of metal fine particles embedded in a polymer dispersant matrix. This composite material combines the electrical conductivity of metal particles with the mechanical flexibility and bending resistance of the polymer, achieving both electrical and mechanical performance requirements.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If metal fine particles are used without proper dispersion, then application is simple, but electrical conductivity and bending resistance are insufficient

Engineering Contradiction:
Improveapplication simplicityVSAvoidelectrical conductivity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The polymer dispersant acts as a mediator that simultaneously provides dispersion stability, adhesion, and electrical connectivity. By incorporating this intermediary substance, the patent maintains simple application processes while achieving reliable electrical conductivity and mechanical durability through the polymer-facilitated particle network.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 method enables the formation of electrically conductive images with ordinary-temperature sintering properties, excellent electrical conductivity, and improved bending resistance, suitable for various applications including flexible substrates.

Implementation Method 1

metal fine particles (a) dispersed with a polymer B

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

the substrate has a porous surface

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS12305055B2Method for manufacturing electrically conductive member
Publication Date: 2025.05.20 KAO CORP

AI summary

The present invention relates to a method for producing an electrically conductive member which includes the step of applying an electrically conductive ink containing a metal fine particle dispersion to a substrate to form electrically conductive images on the substrate under ordinary-temperature environments, thereby obtaining the electrically conductive member, in which the metal fine particle dispersion contains metal fine particles (a) dispersed therein with a polymer B; a glass transition temperature of the polymer B is not higher than a temperature at which the electrically conductive images are formed on the substrate; and the substrate has a porous surface.