Highly Conductive Silver Coatings for Thin EMI Shielding
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Solution Overview
Problem
Current methods for electromagnetic interference (EMI) shielding in electronic packages face limitations, including inferior conductivity in conductive coatings, difficulty in achieving uniform three-dimensional thin coatings, and high material costs, especially with sputtering processes, which compromise EMI shielding effectiveness.
Innovation Solution
Development of highly conductive compositions comprising a high percentage of conductive fillers (such as silver, copper, and alloys) combined with organic matrices and diluents, applied using methods like electrostatic spray, air spray, and ultrasonic spray processing to achieve uniform, thin coatings on electronic packages, providing effective EMI shielding with improved adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive paste adhesives are used for EMI shielding protection, then EMI shielding protection is provided, but very thick films are needed to achieve desired shielding performance due to insufficient electrical conductivity
Solution Approach 1:
The patent changes the key parameter of electrical conductivity by using highly conductive metal particles (silver, copper, nickel) with controlled size distribution (0.5-10 micrometers) and optimized particle morphology. This parameter change enables thin films (1-5 micrometers) to achieve the desired EMI shielding performance without requiring thick coatings
Solution Approach 2:
The patent creates a composite material system combining metal particles with a binder matrix, where the metal particles provide conductivity and shielding while the binder provides adhesion and structural integrity. This composite approach allows thin film formation with high EMI shielding effectiveness
2Reliability
If sputtering processes are used for metal coatings, then high electrical conductivity and effective EMI shielding are achieved, but equipment cost is very expensive and unit per hour productivity is very low
Solution Approach 1:
The patent replaces the complex sputtering mechanical system (vacuum chambers, plasma generation equipment, ion bombardment mechanisms) with a simpler spray deposition process that uses aerosol or liquid suspension delivery. This substitution maintains high conductivity and EMI shielding effectiveness while dramatically improving productivity and reducing equipment costs
Solution Approach 2:
The patent changes the deposition method parameters from vacuum-based sputtering to atmospheric or near-atmospheric spray deposition, enabling faster processing speeds and higher throughput while achieving comparable or superior coating quality
3Reliability
If sputtering processes are used for metal coatings, then high electrical conductivity and effective EMI shielding are achieved, but equipment cost is very expensive
Solution Approach 1:
The patent replaces expensive sputtering equipment (vacuum systems, plasma sources, precision control mechanisms) with simpler spray deposition equipment that can be implemented using standard industrial spray tools. This substitution drastically reduces equipment investment while maintaining EMI shielding effectiveness
Solution Approach 2:
The patent uses consumable spray materials (pastes, suspensions, or aerosols) that can be easily replenished, replacing the need for expensive, maintenance-intensive sputtering systems. The spray materials are delivered in ready-to-use formulations that simplify the overall system complexity
4Ease of operation
If regular spray or printing processes are used for conductive coatings, then ease of application is provided, but uniform three-dimensional thin coating is difficult to produce
Solution Approach 1:
The patent introduces a carefully formulated binder matrix as an intermediary that controls particle distribution and coating flow. This binder acts as a mediator between the metal particles and the substrate, enabling uniform coating formation on three-dimensional surfaces while maintaining simplicity in the application process
Solution Approach 2:
The patent optimizes parameters including particle size distribution (0.5-10 micrometers), viscosity of the coating formulation, and spray deposition conditions to achieve uniform thin coatings on complex geometries. These parameter optimizations enable regular spray processes to produce precise, uniform coatings
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 achieves excellent EMI shielding performance with very thin coatings (as low as 1-2 μm thickness), high conductivity, and improved productivity, comparable to metal coatings, while maintaining low material costs and ease of application.
Implementation Method 1
employing suitable means, e.g., by electrostatic spray processing
Implementation Method 2
ultrasonic spray processing
Data Source
AI summary
Provided herein are highly conductive compositions (having a volume resistivity no greater than 1×10−3 Ohms·cm) using silver flake, powder or suspension in solvent for electromagnetic interference (EMI) applications. This high conductivity will allow the use of very thin films for EMI shielding protection, which in turn will be helpful to reduce package sizes. In some embodiments, the coating composition is applied on the device surface by suitable means, e.g., by an electrostatic spray process, air spray process, ultrasonic spray process, spin coating process, or the like.