Conductive Adhesive Using Silver-Coated Particles for Low Resistivity

Solution Overview

Problem

Existing electrically conductive adhesives require high loadings of expensive conductive metals like silver, which reduces conductivity and stability at room temperature, limiting their use in electronic assembly operations.

Innovation Solution

A thermally curable adhesive composition comprising 6-15 wt.% epoxy resins, 72-82 wt.% silver-coated particles with 8-12 wt.% silver content, and 4-6 wt.% amine-epoxy adducts derived from alkyl-substituted nitrogen-containing heterocycles, providing good electrical conductivity and stability at room temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high loadings of silver fillers are used, then electrical conductivity is improved, but cost increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidcost

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent replaces expensive silver fillers with cheaper base metal fillers (copper, aluminum, nickel, or their alloys) that provide sufficient electrical conductivity at lower cost. The core invention uses these inexpensive metallic particles as the primary conductive filler, eliminating the need for costly silver while maintaining functional performance in electrically conductive adhesives.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates composite filler structures by coating base metal particles with conductive materials. Specifically, it uses core-shell structures where base metal cores (copper, aluminum, nickel) are coated with conductive polymers or carbon materials, forming composite particles that provide both mechanical stability and electrical conductivity at reduced cost compared to pure silver fillers.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If silver-coated particles are used to reduce cost, then cost decreases, but electrical conductivity is significantly reduced

Engineering Contradiction:

ImprovecostVSAvoidelectrical conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent replaces expensive silver-coated particles with cheaper base metal particles (copper, aluminum, nickel or their alloys) that provide sufficient electrical conductivity at lower cost. The core invention uses these inexpensive metallic particles as the primary conductive filler, eliminating the need for costly silver coatings while maintaining functional performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates composite filler structures by coating base metal particles with conductive materials. Specifically, it uses core-shell structures where base metal cores (copper, aluminum, nickel) are coated with conductive polymers or carbon materials, forming composite particles that provide both mechanical stability and electrical conductivity at reduced cost compared to silver-coated alternatives.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If silver-coated metal fillers are used, then cost decreases, but stability at room temperature is insufficient

Engineering Contradiction:

ImprovecostVSAvoidstability at room temperature

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent replaces expensive silver-coated metal fillers with cheaper base metal fillers (copper, aluminum, nickel, or their alloys) that provide sufficient electrical conductivity at lower cost. The core invention uses these inexpensive metallic particles as the primary conductive filler, eliminating the need for costly silver while maintaining functional performance in electrically conductive adhesives.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates composite filler structures by coating base metal particles with conductive materials. Specifically, it uses core-shell structures where base metal cores (copper, aluminum, nickel) are coated with conductive polymers or carbon materials, forming composite particles that provide both mechanical stability and electrical conductivity at reduced cost compared to silver-coated alternatives.

Inventive Principle:

Principle #40Composite materials

4Reliability

If high loading of conductive fillers is used, then electrical conductivity is improved, but viscosity increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidviscosity

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent optimizes the particle size distribution and shape of the metallic filler particles to reduce viscosity. By controlling particle morphology and size, the formulation achieves high filler loading (60-90 wt%) while maintaining manageable viscosity for processing. The use of irregularly shaped particles and specific size distributions prevents excessive particle packing that would increase viscosity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite filler structures by coating base metal particles with conductive materials. Specifically, it uses core-shell structures where base metal cores (copper, aluminum, nickel) are coated with conductive polymers or carbon materials, forming composite particles that provide both mechanical stability and electrical conductivity at reduced cost compared to silver-coated alternatives.

Inventive Principle:

Principle #40Composite materials

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 adhesive achieves a stable electrical conductivity and adhesion, with low volume resistivity and extended worklife, suitable for various electronic assembly operations without requiring inert atmospheres during curing.

Implementation Method 1

4 to 6 wt.-% based on the total amount of the adhesive of one or more amine-epoxy adducts, comprising one or more functional groups, each derived from an alkyl-substituted nitrogen-containing heterocycle

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

72 to 82 wt.-% based on the total amount of the adhesive of silver-coated particles having a silver content of 8 to 12 wt.-%, based on the total amount of the silver-coated particles

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

a) 6 to 15 wt.-% based on the total amount of the adhesive of one or more epoxy resins

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2758481B1Electrically conductive adhesives comprising silver-coated particles

Publication Date: 2021.04.21 HENKEL KGAA

AI summary

The present invention relates to adhesives that are suitable for use as electrically conductive materials in the fabrication of electronic devices, integrated circuits, semiconductor devices, passive components, solar cells, solar modules, and/or light emitting diodes. The adhesive of the present invention comprises one or more epoxy resins, silver-coated particles having a silver content of 2 to 30 wt.-%, based on the total amount of the silver-coated particles, and one or more amine-epoxy adducts, comprising one or more functional groups, each derived from an alkyl-substituted nitrogen-containing heterocycle.