Guard PCB Shielding Signal Wires in Foldable Devices
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Solution Overview
Problem
In electronic devices using high-frequency signals, such as those in next-generation wireless communication, the proximity of conductors to signal wires on printed circuit boards (PCBs) increases impedance and signal transmission loss, degrading RF performance.
Innovation Solution
A printed circuit board configuration with a separate guard PCB spaced apart from the signal wire-bearing PCB, utilizing a microstrip structure with a ground layer and dielectric material, and including flexible portions for deformation, to minimize the influence of conductors and maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conductors are placed close to signal wires on PCB to reduce device size, then device compactness is improved, but impedance and signal transmission loss increase
Solution Approach 1:
A guard PCB is introduced as an intermediary component between the signal wire-bearing PCB and adjacent conductors. The guard PCB includes a ground layer with openings that selectively shield signal wires from nearby conductors while maintaining necessary device compactness. This mediator structure reduces unwanted electromagnetic coupling without requiring increased separation distance.
Solution Approach 2:
The shielding function is segmented and applied only where needed. The ground layer of the guard PCB contains openings that remove shielding in certain areas while maintaining it in others, allowing selective protection of signal wires from conductors based on their specific spatial relationships and interference risks.
2Reliability
If guard PCB is added to shield signal wires from conductors, then signal transmission performance is improved, but device complexity increases
Solution Approach 1:
The guard PCB is electrically connected to the signal wire-bearing PCB through via holes, merging their electrical potentials. This integration reduces the need for separate grounding structures and simplifies the overall device architecture while maintaining effective shielding.
Solution Approach 2:
The ground layer of the guard PCB serves multiple functions: it provides electromagnetic shielding for signal wires, establishes a reference potential plane, and offers a grounding path. This multi-functionality reduces the need for additional dedicated shielding components.
3Reliability
If ground layer is made continuous to improve shielding, then signal transmission performance is improved, but flexibility and deformability decrease
Solution Approach 1:
The ground layer is designed with a porous structure containing openings rather than being completely continuous. These openings maintain the mechanical flexibility and deformability of the PCB while the remaining ground material provides sufficient electromagnetic shielding and reference potential for signal transmission.
Data Source
AI summary
Various embodiments relate to an apparatus. The apparatus may include: a first printed circuit board including a first ground layer having one or more openings formed therein and a wiring layer on which a signal wire is disposed; a second printed circuit board including a second ground layer having one or more openings formed therein; a first area and a third area in which the first printed circuit board and the second printed circuit board are connected to each other via an insulating layer; and a second area, which extends from the first area to the third area, and in which the first printed circuit board and the second printed circuit board are spaced apart from each other, with an air layer interposed therebetween. Various other embodiments may be possible.