Conductive Silicone Adhesive with Cu-Ag Core-Shell Particles
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Solution Overview
Problem
Existing electrically conductive adhesive (ECA) compositions struggle to maintain low volume resistivity with reduced silver content below 15 wt% and prevent copper oxidation in heated or damp conditions, leading to unsatisfactory performance in applications like photovoltaic cell modules.
Innovation Solution
A curable silicone composition incorporating copper-silver (Cu—Ag) core-shell particles with a concentration of 70-89 wt% Cu—Ag particles and 7-14 wt% total silver, which remains conductive and non-oxidized due to the absence of oxygen-oxidizing organic materials, resulting in an electrically conductive silicone adhesive with a volume resistivity below 0.020 Ohm-centimeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If silver content is reduced below 15 wt% to lower cost, then manufacturing cost decreases, but volume resistivity increases above acceptable levels
Solution Approach 1:
The invention uses Cu-Ag core-shell particles where a copper core provides cost benefits and the silver shell provides electrical conductivity. This composite structure allows total silver content to be reduced below 15 wt% while maintaining volume resistivity below 0.020 Ohm-centimeter, resolving the contradiction between cost reduction and electrical performance
Solution Approach 2:
Instead of uniformly distributing silver throughout the adhesive, the invention concentrates silver in the shell layer of core-shell particles. This localized silver distribution at the particle surface provides effective electrical conduction pathways while minimizing total silver content, achieving both cost reduction and maintaining electrical performance
2Loss of substance
If copper particles are used to replace silver to reduce cost, then manufacturing cost decreases, but copper oxidizes in heated or damp conditions leading to performance degradation
Solution Approach 1:
The silver shell is applied to the copper core in advance to create a protective barrier against oxidation. This preliminary protective action prevents copper from reacting with oxygen in heated or damp conditions, eliminating the harmful oxidation effect while maintaining the cost benefits of using copper
Solution Approach 2:
The Cu-Ag core-shell particle structure combines copper's cost advantages with silver's oxidation resistance and electrical conductivity. The composite structure prevents copper oxidation while enabling silver content reduction, simultaneously addressing both the cost reduction goal and the oxidation prevention requirement
3Reliability
If high silver content (70 wt% or more) is used to maintain low volume resistivity, then electrical performance is satisfactory, but manufacturing cost increases significantly
Solution Approach 1:
The Cu-Ag core-shell particles create a composite conductive network where the copper core contributes to conductivity and the silver shell provides surface conduction pathways. This composite approach achieves volume resistivity below 0.020 Ohm-centimeter with total silver content reduced to 7-14 wt%, dramatically reducing silver usage compared to traditional 70 wt% silver formulations
Solution Approach 2:
The invention changes the particle structure parameter from pure silver or copper particles to Cu-Ag core-shell particles with specific composition ranges (70-89 wt% Cu—Ag particles, 7-14 wt% total silver). This parameter change enables achieving satisfactory electrical performance with reduced silver content, resolving the contradiction between electrical performance 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 solution effectively reduces silver usage while maintaining low volume resistivity and preventing copper oxidation, enhancing the electrical performance and durability of ECAs in various applications, including photovoltaic cell modules.
Implementation Method 1
facilitates transfer of electric current between them via the ECA during operation of the electrical device
Implementation Method 2
preventing copper oxidation, enhancing the electrical performance and durability of ECAs
Data Source
AI summary
A curable silicone composition comprising a curable organosiloxane composition, copper-silver (Cu—Ag) core-shell particles, and hydrocarbon vehicle; the curable silicone composition being characterizable by: a concentration of the Cu—Ag core-shell particles of from 70 to 89 weight percent and a total concentration of silver of from 7.0 to 14 weight percent, all based on weight of the curable silicone composition; wherein the composition remains curable to an electrically conductive silicone adhesive having a volume resistivity of less than 0.020 Ohm-centimeter measured according to Volume Resistivity Test Method.