PCB Signal Trace Shielding Against Cross-Talk
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Solution Overview
Problem
In printed circuit boards (PCBs) with densely packed circuit components, signal trace distances must be reduced to enhance transmission speed, leading to cross-talk interference and vulnerability to electromagnetic interference (EMI) from open sides, which affects signal transmission quality.
Innovation Solution
A circuit structure with a signal trace surrounded by reference traces and conductive layers, forming a circular wall to reduce cross-talk and shield against EMI, achieved through a method involving dielectric and conductive layers with specific groove patterns and material deposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distances between signal traces are reduced to increase circuit density, then the circuit layout area is improved, but cross-talk interference between signal traces increases
Solution Approach 1:
Reference traces are introduced as intermediary elements between signal traces. These reference traces act as mediators that provide electromagnetic shielding and reduce cross-talk interference between adjacent signal traces, enabling closer spacing while maintaining signal integrity.
Solution Approach 2:
The circuit board structure is modified locally by adding reference traces specifically positioned between signal traces. This local modification provides targeted electromagnetic shielding where needed, without requiring changes to the entire circuit board design, thus reducing cross-talk in critical areas while maintaining overall layout efficiency.
2Object-affected harmful factors
If additional protection objects are added to shield signal traces from electromagnetic waves, then electromagnetic interference protection is improved, but device complexity increases
Solution Approach 1:
The reference traces serve multiple functions simultaneously: they act as electromagnetic shields protecting signal traces from interference, provides reference planes for signal return paths, and maintain consistent impedance characteristics. This multi-functionality reduces the need for separate dedicated shielding structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The electromagnetic shielding function is merged with the existing trace structure by using reference traces that are already part of the circuit board's conductive layer system. This integration approach combines shielding functionality with the signal transmission infrastructure, avoiding the need for separate additional shielding components and reducing overall structural complexity.
Data Source
AI summary
A circuit structure includes an inner circuit layer, a first and a second dielectric layers, a first and a second conductive material layers, and a second and a third conductive layers. The first dielectric layer covers a first conductive layer of the inner circuit layer and has a first surface and first circuit grooves. The first conductive material layer is disposed inside the first circuit grooves. The second conductive layer is disposed on the first surface and includes a signal trace and at least two reference traces. The second dielectric layer covers the first surface and the second conductive layer and has a second surface and second circuit grooves. Widths of the first and the second circuit grooves are smaller than that of the reference traces. The second conductive material layer is disposed inside the second circuit grooves. The third conductive layer is disposed on the second surface.