Silver-Coated Copper Nanowire Paste for Low-Resistance EMI Shielding
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Solution Overview
Problem
Conductive pastes using silver powder are expensive and require high amounts to achieve desired conductivity, leading to voids and insufficient electrical contact, while alternatives are needed to reduce silver usage and maintain high conductivity and thermal stability.
Innovation Solution
A conductive paste composition using silver-coated copper nanowires with a core-shell structure, combined with a binder mixture of silicone and hydrocarbon-based resins, and an organic solvent, reduces silver content while maintaining high conductivity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver powder is used to achieve high conductivity, then electrical conductivity is improved, but cost increases and silver content must be high (at least 80 wt%)
Solution Approach 1:
The patent uses silver-coated copper nanowires with a core-shell structure, where copper nanowires form the core and silver forms the shell. This composite structure allows the copper core to provide structural integrity and conductivity pathways, while the silver shell provides excellent electrical conductivity and oxidation resistance. The result is a conductive paste that achieves high conductivity with reduced silver content compared to traditional silver powder formulations.
Solution Approach 2:
The patent changes the physical parameters of the conductive filler by using nanowires with specific aspect ratios and dimensions rather than conventional spherical silver particles. The silver-coated copper nanowires have lengths of 1-100 μm and diameters of 50-500 nm, creating a high aspect ratio structure that forms efficient conductive networks at lower fillers concentrations, thereby reducing the required silver content while maintaining conductivity.
2Stability of the object's composition
If silver powder is used to ensure stability, then oxidation resistance is improved, but cost increases
Solution Approach 1:
The silver shell in the core-shell structure provides oxidation resistance and stability, while the copper core provides cost-effectiveness. The thin silver coating (5-50 nm thickness) is sufficient to protect the copper core from oxidation, eliminating the need for bulk silver that would be required for both conductivity and stability in traditional formulations.
3Reliability
If silver particles are used to achieve desired conductivity, then electrical contact is improved, but voids are formed between particles
Solution Approach 1:
The patent transitions from zero-dimensional spherical silver particles to one-dimensional nanowire structures. This dimensional change allows the conductive fillers to form interconnected networks and pathways more efficiently, reducing void spaces between particles. The high aspect ratio of the nanowires enables them to bridge gaps and create continuous conductive paths at lower fillers concentrations.
Solution Approach 2:
The core-shell structure of silver-coated copper nanowires creates a hybrid material that combines the advantages of both metals, forming a stable composite that maintains structural integrity and electrical contact without the void formation issues associated with spherical silver particles.
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 composition achieves excellent adhesion, dispersibility, and electrical conductivity, with low sheet and specific resistance, suitable for high-temperature applications and various electronic components.
Implementation Method 1
silver-coated copper nanowires with a core-shell structure... excellent conductivity
Implementation Method 2
binder mixture containing a silicone resin binder and a hydrocarbon-based resin binder... excellent adhesiveness to a substrate
Data Source
AI summary
A conductive paste composition according to the present disclosure contains silver-coated copper nanowires with a core-shell structure; a binder mixture containing a silicone resin binder and a hydrocarbon-based resin binder; and an organic solvent, such that the conductive paste composition has a low sheet resistance and may withstand a high temperature, thereby implementing excellent conductivity and electromagnetic wave shielding properties. Furthermore, the conductive paste may be widely used in various fields such as electromagnetic wave shielding, solar cell electrodes, electronic circuits, and antennas.