Metal-Coated Conductive Particles for Lower-Loading Z-Axis Bridging

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Solution Overview

Problem

Existing conductive adhesive transfer tapes with spherical particles have limitations in creating a larger conductive pathway and require higher particle loading for equivalent conductivity, lacking sharper points of contact and increased surface area.

Innovation Solution

Conductive particles with a core particle and adhered surface particles, coated with metal, provide a structure with sharper points of contact and greater surface area, allowing for lower particle loading and improved conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If standard bell curve particle size distribution is used, then manufacturing is simple, but only the largest particles bridge the gap between conductive surfaces

Engineering Contradiction:
Improveparticle size distributionVSAvoidconductive pathway formation
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The conductive particle is segmented into a core particle and multiple surface particles. The core particle provides structural support while the surface particles create multiple contact points with the conductive surfaces, enabling reliable conductive pathway formation even with simplified manufacturing processes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The conductive particle is constructed as a composite structure with a core particle and surface particles coated with conductive material. This composite design combines the advantages of different materials and structures to achieve both ease of manufacture and reliable conductivity bridging.

Inventive Principle:
Principle #40Composite materials

2Reliability

If higher particle loading is used, then conductivity is improved, but cost increases and particle density increases

Engineering Contradiction:
ImproveconductivityVSAvoidparticle loading
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The surface particles are coated with conductive material to concentrate conductivity at the contact points with the conductive surfaces. This local quality enhancement ensures that even at lower particle loadings, the critical contact zones have high conductivity, reducing the overall quantity of conductive particles needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The surface particles can rotate and reposition themselves to optimize contact with the conductive surfaces, creating dynamic adaptability that maintains conductivity at lower particle loadings compared to fixed spherical particles.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If smooth surface spherical particles are used, then manufacturing is easy, but surface area and points of contact are limited

Engineering Contradiction:
Improveparticle shapeVSAvoidsurface area
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The particle is divided into a core and multiple surface particles, with each surface particle contributing additional surface area and potential contact points. This segmentation dramatically increases the total surface area available for contact with conductive surfaces while maintaining manufacturing simplicity through a modular structure.

Inventive Principle:
Principle #1Segmentation

4Length of stationary object

If larger conductive pathway is desired, then particle size must increase, but particle loading volume increases

Engineering Contradiction:
Improveconductive pathway lengthVSAvoidparticle loading volume
Core Design Contradiction:
Length of stationary objectVSVolume of stationary object

Solution Approach 1:

Instead of increasing particle size in all dimensions, the invention extends the conductive pathway vertically by stacking surface particles on the core particle. This dimensional approach creates a taller, narrower particle structure that achieves longer conductive pathways without proportionally increasing the volume occupied by each particle in the adhesive matrix.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 new conductive particles offer enhanced conductivity in the z-axis and cost savings by reducing the need for higher particle loading, while maintaining or exceeding conductivity levels.

Implementation Method 1

conductive particles that include: a core particle including at least one of a glass, a glass-ceramic, or a metal; surface particles adhered to the core particle; and a metal coating disposed on at least a portion of the core and surface particles

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

conductive adhesive transfer tapes include conductive particles to bridge the gap between conductive surfaces bonded by the matrix adhesive

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3559958B1Conductive particles, articles, and methods
Publication Date: 2026.01.21 3M INNOVATIVE PROPERTIES CO
  • EP3559958B1 patent drawingFigure 1~2
  • EP3559958B1 patent drawingFigure 3~4
  • EP3559958B1 patent drawingFigure 5~7

AI summary

Conductive particles, articles including such particles, and methods of making such conductive particles, are provided; wherein the conductive particles include: a core particle including at least one of a glass, a glass-ceramic, or a metal; surface particles adhered to the core particle; and a metal coating disposed on at least a portion of the core and surface particles; wherein the core particle is larger than the surface particles.