Metallic Ink Composition for Anti-Aggregation Sintering

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Solution Overview

Problem

Metal inks used for forming metal layers face issues such as reduction in denseness of a sintered body due to aggregation of metal particles, and cleaning liquids with high viscosity or alkalinity cause residue and device corrosion.

Innovation Solution

A metal ink comprising metal particles, a solvent, a polyhydric alcohol with two or more OH groups, and a phosphate compound, along with optional organic solvents and dispersants, is used to improve sinterability and prevent particle aggregation, while a cleaning liquid with similar components prevents clogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If metal particles are dispersed in a liquid to form metal ink, then the ink can be ejected from nozzles, but the metal particles aggregate over time or in high-temperature environments, reducing sintered body denseness

Engineering Contradiction:

Improveejectability from nozzlesVSAvoidstability against aggregation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

A polymer compound with specific functional groups acts as an intermediary between metal particles and the liquid medium. The polymer's functional groups coordinate with metal particles to prevent aggregation, while the polymer itself remains soluble in the liquid carrier, enabling stable dispersion and ejectability without aggregation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the liquid medium by incorporating a polymer compound with specific functional groups (carboxyl, hydroxyl, or amine groups) at controlled concentrations (0.1-10 wt%). This modifies the interaction parameters between metal particles and liquid, preventing aggregation while maintaining ejectability

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a cleaning liquid containing organic solvents and surfactants is used, then cleaning capability is improved, but high viscosity causes residue agglomeration and defects

Engineering Contradiction:

Improvecleaning capabilityVSAvoidresidue quality

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The cleaning liquid uses a low-viscosity aqueous polymer solution instead of high-viscosity organic solvent mixtures. The polymer concentration is controlled at 0.1-10 wt% to achieve optimal cleaning capability while maintaining low viscosity to prevent residue agglomeration and ensure high-quality residue-free surfaces

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a highly alkaline cleaning solution is used, then cleaning power is increased, but the alkali corrodes device members

Engineering Contradiction:

Improvecleaning powerVSAvoiddevice corrosion

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical nature of the cleaning liquid from highly alkaline to a near-neutral aqueous polymer solution (pH 6-8). This eliminates corrosive effects on device members while the polymer's chelating functional groups provide sufficient cleaning power by binding to metal particles and organic residues

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The aqueous polymer solution acts as a gentle intermediary cleaning medium that removes residues without the corrosive effects of strong alkalis. The polymer's functional groups provide cleaning capability through coordination chemistry rather than aggressive alkaline attack, protecting device members from corrosion

Inventive Principle:

Principle #24Intermediary (Mediator)

4Temperature

If silver paste is used to form a metal layer, then heat resistance is excellent, but material cost is higher compared to copper paste

Engineering Contradiction:

Improveheat resistanceVSAvoidmaterial cost

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention uses copper particles instead of silver particles, changing the material parameter to reduce cost. The aqueous polymer dispersion technology enables copper particles to be processed and sintered effectively, achieving cost savings while maintaining acceptable thermal performance for the application

Inventive Principle:

Principle #35Parameter changes

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 enhances sinterability and light transmission of the sintered body and improves cleanability to prevent clogging, ensuring stable operation and extended device life.

Implementation Method 1

a polyhydric alcohol containing two or more OH groups and being soluble in water and a lower alcohol

Methodology Applied

Scientific EffectChelation:

Implementation Method 2

an additive containing a phosphate compound soluble in water

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentEP4667137A1Metallic ink, method for producing metallic ink, method for producing sintered object, sintered object, and liquid detergent

Publication Date: 2025.12.24 MITSUBISHI MATERIALS CORP

Figure 1~2

AI summary

When used as a metal ink, it is possible to improve sinterability while suppressing aggregation of metal particles and to obtain a sintered body that appropriately transmits visible light, and when used as a cleaning liquid, it suppresses or eliminates clogging by improved cleanability. A metal ink (10) includes metal particles (12), a solvent (16), a polyhydric alcohol (14) containing two or more OH groups and being soluble in water and a lower alcohol, and an additive (17) containing a phosphate compound soluble in water.