PCB Trans-Conductor Layers for EMI Absorption
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Solution Overview
Problem
Conventional EMI shielding techniques, such as Faraday cages, are bulky and ineffective in certain applications, leading to premature activation of electrically initiated devices (EIDs) due to incident electric fields, especially in devices with limited internal space.
Innovation Solution
Embedding trans-conductor layers (TCLs) made of nickel-metal composite materials within the printed circuit board assembly (PCBA) to absorb and redirect incident broadband RF and resonant electrical fields, preventing energy dissipation to sensitive areas and steering currents away from EIDs through thermal conductance and reactance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Faraday cages are used for EMI shielding, then electromagnetic interference protection is improved, but device size and weight increase
Solution Approach 1:
The patent changes the fundamental parameter of EMI protection from reflective shielding (Faraday cage) to absorptive shielding (lossy dielectric material). This parameter change allows the shield to protect sensitive components without requiring the bulky metallic enclosure structure, thereby reducing weight while maintaining EMI protection effectiveness.
Solution Approach 2:
The patent employs a thin film or layer of lossy dielectric material applied to or near the PCBA instead of a rigid metallic enclosure. This thin film approach provides EMI protection while minimizing added weight and volume, directly addressing the contradiction between protection effectiveness and weight.
2Object-affected harmful factors
If Faraday cages are used for EMI shielding, then electromagnetic interference protection is improved, but device volume increases
Solution Approach 1:
The patent transitions from reflective shielding requiring large metallic enclosures to absorptive shielding using lossy dielectric materials. This parameter change enables EMI protection to be achieved with minimal volume addition, as the lossy material can be applied as a thin layer directly on or near the circuit board.
Solution Approach 2:
The lossy dielectric material is integrated into the existing PCBA structure by applying it to the board surface or embedding it within layers of the circuit board. This nesting approach incorporates the EMI shield within the existing device volume without requiring additional external space.
3Object-affected harmful factors
If reflective EMI shields are used, then electromagnetic interference protection is improved, but cavity resonance effects worsen
Solution Approach 1:
The patent changes the shielding mechanism from reflection to absorption. By using lossy dielectric material with appropriate loss tangent properties, incident electromagnetic energy is absorbed and converted to heat rather than being reflected. This eliminates cavity resonance effects that occur with reflective shields, as there is no reflected energy to create standing waves within cavities.
Solution Approach 2:
The patent converts harmful electromagnetic energy that would otherwise be reflected and cause cavity resonance into beneficial heat energy through absorption. The lossy dielectric material dissipates incident RF energy as heat, transforming the harmful electromagnetic field into a harmless thermal effect and eliminating cavity resonance problems.
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 TCLs effectively prevent premature activation of EIDs by managing electric field effects within the PCBA, ensuring reliable operation even in high-intensity electric fields without the need for bulky shielding, thus enhancing protection in sensitive applications.
Implementation Method 1
Embedding trans-conductor layers (TCLs) made of nickel-metal composite materials within the printed circuit board assembly (PCBA) to absorb and redirect incident broadband RF and resonant electrical fields
Implementation Method 2
steering currents away from EIDs through thermal conductance and reactance
Implementation Method 3
steering currents away from EIDs through thermal conductance and reactance
Data Source
AI summary
A printed circuit board assembly (PCBA) controls an electrically initiated device (EID) in an electric field. The PCBA includes a conductive layer, a dielectric layer, and a trans-conductive layer (TCL). The conductive layer of the PCBA designated protected areas. An electrical current with a predetermined current density is impressed in the conductive layer when the PCBA is in the electric field. The TCL is a nickel-metal composite metamaterial positioned between the conductive and dielectric layers and configured to change in shape or thickness in the electric field such that the impressed current is steered away from the conductive layer and into the dielectric layer to prevent premature activation of the EID. A system includes an outer housing, power supply, an EID such as a sonobuoy or medical device, and the PCBA, all of which are encapsulated in the housing. A method is also disclosed for manufacturing the PCBA.