RF Filtering in PWB DC Distribution Layers
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Solution Overview
Problem
Radio frequency (RF) leakage through direct current (DC) distribution paths in printed wiring boards (PWBs) leads to crosstalk and undesirable effects, as existing RF filtering methods like carbon nanotubes are sensitive to their orientation relative to PWB traces.
Innovation Solution
Embedding ferrite or iron material in epoxy-based laminate layers surrounding the DC distribution traces to create a lossy path for RF energy, eliminating RF leakage by using these layers' inherent absorptive filtering capability, which is independent of trace direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotubes are added to provide RF filtering, then RF filtering capability is improved, but the solution becomes sensitive to the direction of nanotubes relative to PWB traces
Solution Approach 1:
The patent changes the material parameter from carbon nanotubes to ferrite/iron particles embedded in epoxy laminate. This material substitution fundamentally alters the filtering mechanism from directional nanotube alignment to isotropic magnetic loss, eliminating orientation sensitivity while maintaining RF filtering capability
Solution Approach 2:
The patent uses composite material consisting of ferrite or iron particles embedded within epoxy-based laminate layers. This composite structure provides both mechanical support and RF filtering functionality, with the magnetic particles creating lossy paths for RF energy regardless of trace orientation
2Reliability
If ferrite or iron material is embedded in epoxy-based laminate layers, then RF energy attenuation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the RF filtering function with the structural laminate layers by embedding ferrite/iron particles directly into the epoxy-based laminate. This integration eliminates the need for separate filtering components and simplifies manufacturing by incorporating filtering capability into existing PWB construction processes
Solution Approach 2:
The epoxy-based laminate layers with embedded magnetic particles provide inherent RF filtering capability as part of their structural function. The laminate serves dual purposes: mechanical support and RF energy attenuation, eliminating the need for additional dedicated filtering components
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
Effectively attenuates RF energy, preventing cross-contamination between circuits by ensuring RF does not use the DC distribution network as a sneak path, with attenuation increasing with trace length and being less affected by layer thickness.
Implementation Method 1
The first epoxy-based layer includes radio frequency (RF) absorber material. The second epoxy-based layer includes the RF absorber material... effectively attenuates RF energy
Implementation Method 2
Embedding ferrite or iron material in epoxy-based laminate layers surrounding the DC distribution traces to create a lossy path for RF energy
Implementation Method 3
create a lossy path for RF energy, eliminating RF leakage
Data Source
AI summary
A method of fabricating a printed wiring board (PWB) includes etching traces to carry direct current (DC) on a first surface of a first epoxy-based layer. The first epoxy-based layer includes radio frequency (RF) absorber material. The method also includes arranging a second epoxy-based layer. The second epoxy-based layer includes the RF absorber material and includes a first surface in contact with the first surface of the first epoxy-based layer such that the traces are sandwiched between the first epoxy-based layer and the second epoxy-based layer.