Conductive Silicone with Cu-Ag Core-Shell Particles
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Solution Overview
Problem
Existing thermally conductive materials face challenges in achieving high thermal conductivity and electrical conductivity with low silver concentration, while avoiding oxidation of copper-silver core-shell particles, especially in humid conditions, and preventing slump and bleeding during manufacturing.
Innovation Solution
A curable silicone composition comprising copper-silver core-shell particles with a concentration of 80-89 weight percent and a total silver concentration of 7-12 weight percent, which, upon curing, forms a conductive silicone material with a volume resistivity of less than 0.020 Ohm-centimeter and thermal conductivity of greater than 2.9 W/(m*K), minimizing oxidation and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper-silver core-shell particles are used to achieve high thermal and electrical conductivity with low silver concentration, then cost is reduced and conductivity is improved, but oxidation of copper occurs in humid conditions
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the copper-silver core-shell particles and the silicone polymer matrix. The silane coupling agent forms a protective interface layer that prevents direct contact between copper and oxidizing environments, thereby eliminating copper oxidation while maintaining the conductive properties of the core-shell particles
Solution Approach 2:
The patent creates an inert protective environment around the copper-silver core-shell particles through the silicone polymer matrix and silane coupling agent system. This inert environment isolates the copper from oxygen and moisture, preventing oxidation reactions while allowing the particles to maintain their conductive functionality
2Reliability
If high concentration of conductive metal particles is used to achieve high thermal and electrical conductivity, then conductivity is improved, but viscosity is too low causing slump, bleeding, and filler settling during manufacturing
Solution Approach 1:
The patent changes the rheological parameters of the composition by introducing a silane coupling agent that modifies the interaction between particles and polymer matrix. This parameter change increases viscosity and improves thixotropic properties, enabling the composition to maintain stability during manufacturing while preserving high conductive particle concentration
Solution Approach 2:
The patent creates a composite system consisting of copper-silver core-shell particles, silicone polymer matrix, and silane coupling agent. This composite structure allows the different components to work synergistically: the core-shell particles provide conductivity, the polymer matrix provides structural support, and the silane coupling agent provides rheological control and interfacial bonding
3Quantity of substance
If total silver concentration is reduced below 15 wt % to reduce cost, then cost is reduced, but electrical and thermal conductivity and tensile properties deteriorate
Solution Approach 1:
The patent applies local quality by concentrating silver in a thin shell layer around the copper core, rather than distributing silver uniformly. This localized silver placement at the particle surface maximizes conductivity and tensile reinforcement at critical interfaces while minimizing total silver content
Solution Approach 2:
The copper-silver core-shell structure itself is a composite material that combines the high conductivity of silver with the lower cost copper. This composite particle design achieves optimal performance at reduced silver concentrations by leveraging the complementary properties of both metals in a structured arrangement
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 provides a thermally and electrically conductive silicone material with improved tensile properties, suitable for use as a thermal interface material in smaller electronic devices and SiC-based devices, while preventing oxidation and maintaining stability in humid conditions.
Implementation Method 1
Thermally conductive (TC) materials function by conducting heat away from a heat source
Implementation Method 2
The cured product thereof has good electrical and thermal conductivity
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 12 weight percent, all based on weight of the curable silicone composition; wherein the curable silicone composition has a concentration of the Cu—Ag core-shell particles and hydrocarbon vehicle such that the curable silicone composition remains curable to a conductive silicone material having a concentration of the Cu—Ag core-shell particles of from 88.0 to 92 weight percent and having a volume resistivity of less than 0.020 Ohm-centimeter measured according to Volume Resistivity Test Method, and a thermal conductivity of greater than or equal to 2.9 Watts per meter*Kelvin (W/(m*K)) measured according to Thermal Properties Test Method.