Ni Core Conductive Particles for Low Resistivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive particles with NiP cores have higher volume resistivity and lower conductivity compared to high-purity Ni particles, and existing solutions rely on expensive Au plating layers that are prone to issues like migration and oxidation.
Innovation Solution
A conductive particle structure featuring a spherical Ni core with a pure Ni or low P-content plating layer, optionally followed by a thin Au plating layer, to reduce volume resistivity while maintaining cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a NiP core particle is used to achieve larger particle diameter (20-50 μm), then the particle size requirement is satisfied, but the volume resistivity increases and conductivity decreases
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the core particle (NiP) has different properties than the surface plating layers. The core provides the required large particle diameter and structural stability, while the outer plating layers (particularly the Au layer) provide high conductivity and low volume resistivity. This resolves the contradiction by having different regions of the same particle serve different functions - the core for size and the coating for conductivity.
Solution Approach 2:
The patent uses composite materials by combining NiP core particles with metal plating layers (Ni and/or Au). This composite structure allows the particle to simultaneously achieve the desired large diameter from the NiP core while obtaining high conductivity from the metallic plating layers on the surface, thus resolving the contradiction between particle size and conductivity.
2Reliability
If a Au plating layer is formed on the NiP particle surface to improve conductivity, then the volume resistivity decreases, but the manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the Au plating layer to 1 μm or less (preferably 0.01-0.5 μm). This controlled parameter change maintains the essential conductivity improvement provided by the Au layer while significantly reducing the material cost compared to thicker coatings. The thin Au layer is sufficient to provide the required low volume resistivity without incurring excessive manufacturing costs.
Solution Approach 2:
The patent introduces an intermediary Ni plating layer between the NiP core and the Au plating layer. This intermediate layer serves multiple functions: it provides a suitable surface for Au plating, enhances adhesion, and contributes to conductivity. This mediator allows for a thinner, more cost-effective Au layer while maintaining overall conductivity performance.
3Reliability
If a thick Au plating layer is used to ensure stability against migration and oxidation, then the reliability improves, but the manufacturing cost and particle complexity increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Au plating layer thickness to 1 μm or less. This optimized thickness parameter provides sufficient protection against migration and oxidation for the intended applications while avoiding the excessive material use and structural complexity that would result from much thicker layers. The parameter optimization balances protective function with simplicity.
Solution Approach 2:
The patent applies partial action by providing just enough Au plating (1 μm or less) to achieve the required stability and conductivity for the application, rather than using excessive thickness. This partial coverage approach maintains the essential protective and conductive functions while minimizing added complexity and cost.
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 proposed structure achieves lower volume resistivity and improved conductivity for conductive particles, powders, and anisotropic conductive sheets, offering better performance and cost efficiency compared to traditional approaches.
Implementation Method 1
a conductive particle having a structure including a Au plating layer, which has a thickness of 1 μm or less, on a surface of the core
Data Source
Figure 1~3
Figure 4
AI summary
Provided are a conductive particle, a conductive powder, a conductive polymer composition, and an anisotropic conductive sheet, each of which has a particularly smaller volume resistivity and better conductivity than those of the related art, and is desirably inexpensive. A conductive particle (10) includes a first plating layer (12) (pure Ni plating layer or Ni plating layer containing 4.0 mass% or less of P) covering the surface of a spherical Ni core (11) containing 5 mass% to 15 mass% or less of P. The conductive particle may further include a Au plating layer having a thickness of from 5 nm to 200 nm and covering the surface of the first plating layer (12). The conductive powder includes the conductive particles, and has a median diameter d50 of from 3 µm to 100 µm and satisfies (d90-d10)/d50≤0.8. The conductive polymer composition includes the conductive powder and a polymer. The anisotropic conductive sheet is formed from the conductive polymer composition, in which the conductive particles are arranged in the thickness direction of the anisotropic conductive sheet.