Printed Circuit Board Ground Layer Spacing for Signal Loss Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional printed circuit boards experience significant signal loss at high frequencies due to the proximity effect among wiring traces, which is not adequately addressed by existing designs.
Innovation Solution
A printed circuit board design featuring a support substrate with a conductive ground layer of higher conductivity than the substrate, where the ground layer is positioned between the upper wiring trace and the support substrate, and the distance between the ground layer and the upper wiring trace is greater than the distance between the lower and upper wiring traces, reducing electromagnetic coupling and eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground layer is positioned close to the upper wiring trace to reduce electromagnetic coupling, then signal transmission efficiency improves, but eddy current loss increases due to higher electromagnetic coupling with the conductive ground layer
Solution Approach 1:
The patent introduces an insulating layer as an intermediary substance positioned between the ground layer and the upper wiring trace. This insulating layer mediates the electromagnetic interaction by preventing direct conductive coupling while still allowing electromagnetic field penetration, thus reducing eddy currents in the ground layer while maintaining signal transmission efficiency through the upper wiring trace.
Solution Approach 2:
The patent changes the physical parameter of electrical conductivity in the region between the ground layer and upper wiring trace by introducing an insulating material. This parameter change transforms the electromagnetic coupling mechanism from direct conductive coupling (which causes eddy currents) to capacitive or inductive coupling through the insulator, thereby reducing eddy current loss while maintaining signal transmission integrity.
2Device complexity
If wiring traces are positioned closer together to reduce device complexity, then manufacturing simplicity improves, but proximity effect increases causing signal loss
Solution Approach 1:
The patent resolves the proximity effect issue by transitioning from a two-dimensional planar arrangement to a three-dimensional stacked arrangement. The upper wiring trace is positioned in a different vertical layer (on the insulating layer) above the ground layer, allowing traces to be closer in plan view without experiencing the same degree of electromagnetic interference, thus reducing signal loss while maintaining manufacturing simplicity.
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
This configuration significantly reduces signal loss in high-frequency bands by minimizing eddy currents and electromagnetic coupling, thereby enhancing signal transmission efficiency.
Implementation Method 1
When the electromagnetic wave enters the support substrate or the ground layer, an eddy current is generated in the support substrate or the ground layer, and the upper wiring trace and one of the support substrate and the ground layer are electromagnetically coupled to each other
Implementation Method 2
the upper wiring trace and one of the support substrate and the ground layer are electromagnetically coupled to each other
Data Source
AI summary
In a suspension board, a ground layer and a first insulating layer are formed on a support substrate. The ground layer has electric conductivity higher than that of the support substrate. A power wiring trace is formed on the first insulating layer. A second insulating layer is formed on the support substrate to cover the ground layer and the first insulating layer. A write wiring trace is formed on the second insulating layer to at least partially overlap with the ground layer. A distance between the ground layer and the write wiring trace in a stacking direction of the support substrate, the first insulating layer and the second insulating layer is set larger than a distance between the power wiring trace and the write wiring trace in the stacking direction.