Three-Layer Flat Wiring Structure for Noise Suppression
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Solution Overview
Problem
Existing flat wiring structures with a two-layered configuration fail to effectively suppress common mode and radiation noise that leaks to conductors due to stray capacitance and electric field coupling, leading to noise generation in conductors like vehicle body sheet metal.
Innovation Solution
A three-layered flat wiring structure is introduced, where a power supply layer is sandwiched between two ground layers, with the power supply layer having a smaller width than the ground layers, allowing for easier noise feedback and electric field coupling to the ground layers, thereby reducing noise leakage and radiation to conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-layered structure (power supply layer and ground layer) is used, then the structure is simple, but common mode noise and radiation noise leak to conductors through stray capacitance and electric field coupling
Solution Approach 1:
The ground layer is segmented into two separate ground layers (first ground layer and second ground layer) positioned on opposite sides of the power supply layer. This segmentation creates multiple ground reference paths and improves electric field containment, preventing noise leakage to conductors while maintaining structural simplicity
Solution Approach 2:
The invention transitions from a two-layered to a three-layered structure by adding the power supply layer between two ground layers in the thickness direction. This dimensional change creates a sandwich structure that effectively contains electric fields and reduces noise radiation to adjacent conductors
2Power
If the power supply layer width is increased to match ground layer width, then power delivery capacity improves, but electric field coupling to conductor increases causing radiation noise
Solution Approach 1:
The power supply layer is designed with a width smaller than the ground layers, creating a localized field confinement effect. This local quality difference ensures that electric fields are contained within the narrower power supply layer region, reducing coupling to adjacent conductors while maintaining adequate power delivery capacity
Solution Approach 2:
The narrower power supply layer width, which might seem to limit power capacity, actually benefits noise suppression by reducing the radiating aperture. The ground layers are extended beyond the power supply layer edges to provide additional field containment, converting the width difference into a noise suppression advantage
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 three-layered structure significantly reduces common mode and radiation noise by increasing noise current feedback paths and enhancing electric field coupling to the ground layers, achieving a noise suppression improvement of about 10 dB across a wide frequency range compared to two-layered structures.
Implementation Method 1
normal mode noise that is propagating from equipment connected to the flat wiring through the power supply layer is easily fed back to the equipment through the ground layers compared to the two-layered structure of the related art. Accordingly, it is possible to reduce a noise current that leaks and flows from the ground layers to a conductor (for example, a vehicle body sheet metal or the like) close to the flat wiring through stray capacitance or the like
Implementation Method 2
electric lines of force radiated from the power supply layer are easily coupled to the first ground layer or the second ground layer. Accordingly, it is possible to reduce electric lines of force that are coupled to the conductor (for example, a vehicle body sheet metal or the like) close to the flat wiring. Therefore, it is possible to suppress radiation noise that is generated in the conductor
Data Source
AI summary
A flat wiring structure is including a plurality of layers, and includes a power supply layer, and a first ground layer and a second ground layer laminated with the power supply layer sandwiched therebetween. In a plan view of the flat wiring structure when viewed from a direction along a lamination direction of the first ground layer, the power supply layer, and the second ground layer, the power supply layer has a width in a short direction smaller than those of the first ground layer and the second ground layer, and the power supply layer is provided at a position covered with the first ground layer and the second ground layer.