Ultra-thin conductor based semi-transparent electromagnetic interference shielding
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Solution Overview
Problem
Conventional electromagnetic shielding devices are opaque, limiting their use in optical applications, and meta-materials offer narrow-band performance, mechanical inflexibility, and fabrication complexity, making them unsuitable for broad radio frequency band shielding and flexible electronics.
Innovation Solution
A flexible electromagnetic shield with a continuous ultrathin metal film of silver and copper, combined with conductive dielectric layers and a graphene layer, achieving broadband EMI shielding efficiency of ≥20 dB while maintaining ≥65% average visible light transmission through a stack configuration that includes spacer layers and resonator cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional electromagnetic shielding devices are used, then EMI shielding performance is achieved, but visible light transmission is blocked (opacity)
Solution Approach 1:
The patent employs an ultrathin metal film (thickness ≤10 nm) as the core shielding layer, which is thin enough to be substantially transparent to visible light while maintaining EMI shielding capability. This thin film approach allows the shielding device to achieve both EMI protection and optical transparency, directly resolving the contradiction between shielding efficiency and light transmission.
Solution Approach 2:
The patent creates a composite structure combining ultrathin metal film with transparent dielectric materials and conductive dielectric layers. This composite approach enables the system to achieve broadband EMI shielding across multiple frequency ranges while maintaining high visible light transmission, as each material contributes specific properties that complement the others.
2Manufacturing precision
If meta-materials are used for EMI shielding, then narrow-band shielding performance is achieved, but broadband shielding capability is limited
Solution Approach 1:
The patent designs a multi-layer structure where each layer serves multiple functions: the ultrathin metal film provides both optical transparency and EMI shielding, while the transparent dielectric layers contribute to both mechanical flexibility and electromagnetic wave management. This multi-functionality enables broadband shielding across different frequency ranges without requiring separate specialized materials for each band.
Solution Approach 2:
The patent achieves broadband shielding by optimizing parameters such as the thickness of the ultrathin metal film (≤10 nm), the composition ratios of silver and copper (Ag≥80 atomic %, Cu≤20 atomic %), and the properties of surrounding dielectric layers. By carefully controlling these parameters, the system achieves effective shielding across a broad frequency spectrum from microwave to terahertz ranges.
3Object-affected harmful factors
If meta-materials are used for EMI shielding, then shielding performance is achieved, but mechanical flexibility is poor
Solution Approach 1:
The patent uses an ultrathin metal film (≤10 nm) that is inherently flexible and can be bent without cracking or losing its shielding properties. This thin film is combined with flexible transparent dielectric materials to create a mechanically flexible composite structure that maintains EMI shielding performance while enabling applications in flexible electronics and wearable devices.
Solution Approach 2:
The patent divides the shielding structure into multiple thin layers (metal film, dielectric layers, conductive dielectric layers) rather than using a single thick rigid material. This segmentation allows each layer to be thin and flexible, and the stacked configuration maintains overall flexibility while achieving broadband EMI shielding through the combined effect of all layers.
4Object-affected harmful factors
If conventional shielding materials are used, then EMI shielding is achieved, but fabrication complexity and manufacturing cost increase
Solution Approach 1:
The patent employs ultrathin metal films that can be deposited using conventional thin film deposition techniques, which are well-established in the semiconductor and display industries. This approach simplifies fabrication compared to complex meta-material structures, as the thin film can be continuously deposited on large substrates using roll-to-roll processing, enabling scalable and cost-effective manufacturing.
Solution Approach 2:
The patent uses abundant and inexpensive materials such as silver and copper in the ultrathin film, along with common transparent dielectric materials, replacing rare or expensive meta-material components. This material selection significantly reduces manufacturing cost while maintaining effective broadband EMI shielding performance.
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 effective broadband EMI shielding across a wide frequency range while ensuring high transparency and mechanical flexibility, suitable for scalable and cost-effective manufacturing in various applications.
Implementation Method 1
blocking a range of frequencies of greater than or equal to about 600 MHz to less than or equal to about 90 GHz to a shielding efficiency of greater than or equal to 20 dB with the electromagnetic shield
Implementation Method 2
transmitting a range of wavelengths in a visible range of greater than or equal to about 390 nm to less than or equal to about 740 nm to an average visible transmission efficiency of greater than or equal to about 65%
Implementation Method 3
a flexible electromagnetic shield with a continuous ultrathin metal film of silver and copper, combined with conductive dielectric layers and a graphene layer, achieving broadband EMI shielding efficiency of ≥20 dB while maintaining ≥65% average visible light transmission through a stack configuration that includes spacer layers and resonator cavities
Data Source
AI summary
Electromagnetic interference (EMI) shields and methods for broadband EMI shielding are provided. An EMI shield disposed in a path of electromagnetic radiation blocks a broad range of frequencies (>about 800 MHz to <about 90 GHz) to a shielding efficiency of >to 20 dB, while transmitting wavelengths in a visible range to an average transmission efficiency of >about 85% through the electromagnetic shield. The shield includes a flexible stack comprising a continuous ultrathin metal film comprising silver (Ag) and copper (Cu) and two antireflection dielectric layers disposed on either side of the ultrathin metal film. The shield may also include multiple stacks or an optional graphene layer that may be spaced apart from the flexible stack to achieve radiofrequency (RE) absorption, which provides additional form of EMI shielding. The EMI shield can be made via roll-to-roll sputtering.