Printed Circuit Board Ground Layer Shielding High Frequency Signal Loss
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Solution Overview
Problem
Conventional printed circuit boards experience significant signal loss at high frequencies due to the proximity effect and increased line length of wiring traces, which is not adequately addressed by existing technologies.
Innovation Solution
A printed circuit board design featuring a support substrate with a conductive ground layer of higher conductivity than the substrate, an insulating layer with varying thickness portions, and an upper wiring trace that overlaps with these portions, reducing electromagnetic wave entry into the substrate and minimizing line length, thereby reducing signal loss. The ground layer is strategically positioned between the wiring trace and the substrate to shield electromagnetic waves and adjust characteristic impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ground layer is formed on the entire first insulating layer, then electromagnetic wave shielding is improved, but the line length of the upper wiring trace increases and characteristic impedance becomes non-uniform
Solution Approach 1:
The ground layer is selectively formed only on the second portion (thinner region) of the first insulating layer, not uniformly across the entire layer. This local placement provides electromagnetic shielding where needed while avoiding excessive line length and impedance variation in other regions.
Solution Approach 2:
The patent utilizes the thickness dimension of the insulating layer to create functional differentiation. By forming the ground layer on the thinner second portion rather than the entire first insulating layer, it achieves both shielding and signal integrity in the vertical dimension without compromising horizontal trace characteristics.
2Ease of manufacture
If wiring traces are positioned at the same plane, then manufacturing is simplified, but proximity effect increases causing signal loss
Solution Approach 1:
The patent resolves the proximity effect by separating wiring traces in the vertical dimension rather than the horizontal plane. The upper wiring trace is formed on the second insulating layer while lower wiring traces remain on the first insulating layer, creating vertical separation that reduces electromagnetic coupling while maintaining planar manufacturing processes.
3Ease of manufacture
If the first insulating layer has uniform thickness, then manufacturing is easier, but characteristic impedance uniformity deteriorates
Solution Approach 1:
The first insulating layer is designed with non-uniform thickness, having a thinner second portion where the ground layer is formed and a thicker first portion elsewhere. This local thickness variation compensates for the ground layer presence, maintaining uniform characteristic impedance along the upper wiring trace while remaining compatible with standard manufacturing processes.
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 line length, improving signal transmission efficiency and uniformity of characteristic impedance.
Implementation Method 1
the ground layer is positioned between at least part of the upper wiring trace and the support substrate, so that a large part of electromagnetic waves radiated from the upper wiring trace towards the support substrate does not reach the support substrate
Implementation Method 2
When the electromagnetic waves enter the support substrate or the ground layer, an eddy current is generated in the support substrate or the ground layer
Data Source
AI summary
A first insulating layer is formed on a support substrate. The first insulating layer includes a first portion and a second portion. The second portion has a thickness smaller than that of the first portion. A ground layer having electric conductivity higher than that of the support substrate is formed on the second portion of the first insulating layer. The ground layer is electrically connected to the support substrate. A second insulating layer is formed on the first insulating layer to cover the ground layer. A write wiring trace is formed on the second insulating layer to overlap with the first portion and the second portion of the first insulating layer.