Conductive Particles Core-Shell Structure Deformation Recovery
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Solution Overview
Problem
Conductive particles used in electric and electronics materials face challenges with deformation recovery after compressive deformation, leading to connection failures and poor reliability due to low deformation recovery factors and susceptibility to erosion in plating steps, which affects their physical properties.
Innovation Solution
The development of conductive particles with a polymer base particle and a conductive layer, where the compressive elastic deformation characteristic is defined by a specific formula, ensuring a high recovery factor and resistance to acidic or alkaline media, maintaining the soft and highly elastic characteristics of the base particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft low-density cross-linked material is used as base particles to improve deformation recovery, then the particles become softer, but the restoring force is lowered with the lapse of time and connection reliability deteriorates
Solution Approach 1:
The patent uses a core-shell structure where the core is made of soft low-density cross-linked material (styrene-divinylbenzene copolymer) for deformation recovery, and the shell is made of hard thermosetting resin for structural stability and resistance to erosion. This composite structure combines the advantages of both materials to achieve high deformation recovery factor while maintaining connection reliability and restoring force over time.
2Reliability
If base particles are used in plating step to form conductive film, then conductive properties are improved, but the base particles are susceptible to erosion by strongly acidic or strongly alkaline medium, lowering physical properties
Solution Approach 1:
The patent introduces a shell layer made of thermosetting resin as an intermediary protective barrier between the soft base particles and the strongly acidic or alkaline plating medium. This shell layer is resistant to erosion by the plating medium, allowing the conductive film formation process to proceed without damaging the base particles or lowering their physical properties.
3Reliability
If high compression displacement is applied to enhance deformation recovery factor, then the particles may break at compression displacement less than 45%, but it is difficult to enhance deformation recovery factor upon high compression displacement
Solution Approach 1:
The core-shell composite structure allows the soft core to undergo high compression displacement and recover deformation, while the hard shell provides structural integrity and prevents breaking at compression displacements less than 45%. This enables the particles to achieve high deformation recovery factor upon high compression displacement without breaking.
4Ease of operation
If polymer base particles are used to maintain soft and elastic characteristics, then deformation recovery is improved, but the particles show substantial breaking point at compression displacement less than 45%
Solution Approach 1:
The patent creates a composite structure where the soft polymer base particles are coated with a hard thermosetting resin shell. The soft core maintains the elastic characteristics and deformation recovery, while the hard shell prevents breaking at compression displacements less than 45%, achieving both softness and strength.
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 conductive particles exhibit excellent deformation recovery and maintain physical properties, enhancing connection reliability and resistance to erosion, thus suitable for use in conductive materials like micro-device mounting adhesives and anisotropic conductive adhesives.
Implementation Method 1
the recovery factor of particle diameter of the conductive particles when the displacement of particle diameter of the conductive particles is 50% is not less than 30% at 20° C.
Implementation Method 2
the base particles are susceptible to erosion by a strongly acidic or strongly alkaline medium in a plating step, which is a step for forming a conductive film on the base particles
Data Source
AI summary
Conductive particles each includes a polymer base particle and a conductive layer coating the polymer base particle. Let the compressive elastic deformation characteristic KX of one conductive particle when the displacement of particle diameter of the conductive particles is X % be defined by the following formula: KX=(3/√2)·(SX−3/2)·(R−1/2)·FX. FX is the load (N) necessary for X % displacement of the conductive particles. SX is the compressive deformation amount (mm) upon X % displacement of the conductive particles. R is the particle radius (mm) of the conductive particles. The compressive elastic deformation characteristic K50 when the displacement of particle diameter of the conductive particles is 50% is 100 to 50000 N/mm2 at 20° C., and the recovery factor of particle diameter of the conductive particles when the displacement of particle diameter of the conductive particles is 50% is not less than 30% at 20° C.