Silver Nanoparticle Bonding Material for Low-Temperature Press-Free Joining

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Solution Overview

Problem

Conventional silver bonding methods require pressurization and high-temperature heating, limiting their versatility and applicability to materials with sufficient mechanical strength, and are susceptible to silver oxide formation in oxidative atmospheres, which can degrade bonding strength, especially in fine products.

Innovation Solution

A bonding material comprising silver nanoparticles with an average diameter of 1-200 nm coated with an organic material having 8 or less carbon atoms, a flux component with a dicarboxylic acid structure and ether linkage, and a polar dispersion medium, allowing bonding in a nitrogen atmosphere without pressurization or high-temperature heat treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional silver bonding methods are used, then bonding strength can be achieved, but pressurization and high-temperature heating are required which limits versatility and applicability

Engineering Contradiction:

Improvebonding strengthVSAvoidrange of applicable materials

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The invention changes the particle size parameter of silver from conventional large particles to nanoparticles (1-200 nm average diameter), which fundamentally alters the bonding mechanism. This parameter change enables bonding at lower temperatures and without pressurization, thereby expanding the range of applicable materials while maintaining bonding strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite material structure by coating silver nanoparticles with organic material having 8 or less carbon atoms. This composite structure combines the high strength of silver with the low-temperature processing capability of organic coatings, enabling bonding without pressurization and high-temperature heating

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If bonding is performed in oxidative atmosphere, then bonding process can be simplified, but silver oxide formation degrades bonding strength especially in fine products

Engineering Contradiction:

Improvebonding process simplicityVSAvoidbonding strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention applies preliminary protective action by coating silver nanoparticles with organic material before bonding. This coating prevents oxidation during the bonding process, eliminating the need to avoid oxidative atmospheres while maintaining bonding strength. The organic coating acts as a preliminary barrier against oxygen

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The invention converts the potential harm of oxidative atmosphere into a benefit by using the organic coating as a sacrificial layer that protects the silver nanoparticles. The coating can be oxidized instead of the silver, and this controlled oxidation actually facilitates the bonding process while preventing silver oxide formation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If materials with insufficient mechanical strength are used, then design flexibility increases, but conventional pressurization bonding cannot be applied

Engineering Contradiction:

Improvedesign flexibilityVSAvoidbonding process applicability

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The invention replaces the mechanical pressurization system with a chemical bonding mechanism. The organic-coated silver nanoparticles enable bonding through chemical reactions and diffusion at lower temperatures, eliminating the need for mechanical pressurization and enabling bonding of materials with insufficient mechanical strength to resist pressurization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides a bonded product with high bonding strength equivalent to conventional soldering methods but without the need for pressurization or high-temperature heating, enhancing the range of applicable materials and environments.

Implementation Method 1

a bonding method using silver nanoparticles... bonding can be achieved under temperature conditions lower than those for bulk silver

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

a mixture of silver oxide particles and myristyl alcohol is used as a bonding material... carboxylic acid is added to a mixture of silver nanoparticles and silver carbonate or silver oxide

Methodology Applied

Scientific EffectOxidation-reduction reaction: Redox Reactions

Data Source

PatentUS10090275B2Bonding method using bonding material

Publication Date: 2018.10.02 DOWA ELECTRONICS MATERIALS CO LTD

AI summary

A method of bonding two different substances includes the steps of: applying a bonding material containing a flux component that includes an organic material having at least two carboxyl groups to a bonding surface of a bonding object, disposing an object to be bonded on the bonding material, performing preliminary firing at a preset temperature in a state in which the object to be bonded is disposed, and performing a main firing by heating at a temperature higher than the temperature of the preliminary firing.