FPCB Ground Shield Layout for Stable RF Signal Matching
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Solution Overview
Problem
In solder bonding structures of printed circuit boards and flexible printed circuit boards, there is a lack of a ground shield structure, leading to potential mismatching and unstable RF loss, which affects the reliability of communication devices.
Innovation Solution
A flexible printed circuit board design with first, second, and third ground wiring configurations surrounding signal wiring to create a ground shield structure at the coupling part, ensuring stable RF loss and improved matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pads are exposed for solder bonding in the coupling part, then solder bonding accessibility is improved, but ground shield structure cannot be applied leading to RF signal instability
Solution Approach 1:
The coupling part is segmented into multiple functional zones: a solder bonding region with exposed pads for ease of connection, and a ground shield region with complete ground wiring surrounding the signal wiring. This segmentation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the coupling part are assigned different wiring configurations tailored to their specific requirements. The solder bonding region has exposed pads for accessibility, while the ground shield region has complete ground wiring for RF signal stability. This local differentiation resolves the contradiction by optimizing each area for its primary function.
2Reliability
If ground shield structure is applied in the coupling part, then RF signal stability is improved, but solder bonding accessibility deteriorates
Solution Approach 1:
The coupling part is divided into distinct functional zones where the ground shield structure and solder bonding pads coexist in separate but adjacent regions. The ground shield surrounds the signal wiring in the RF-critical area while pads remain exposed in the solder bonding area, eliminating the need to choose between the two requirements.
Solution Approach 2:
The ground shield wiring is configured to surround the signal wiring in a planar arrangement that allows solder pads to be exposed at specific locations. By utilizing the two-dimensional layout of the PCB, the ground shield can enclose the signal path while leaving designated areas open for solder bonding access.
3Reliability
If complete ground wiring is provided around signal wiring, then ground shield effect is improved, but manufacturing complexity increases
Solution Approach 1:
Complete ground wiring is provided only in the ground shield region where it is critical for RF signal stability, rather than uniformly across the entire circuit board. This localized approach maintains the ground shield effect where needed while reducing overall wiring complexity and manufacturing burden.
Solution Approach 2:
The ground wiring is segmented into different configurations based on functional requirements: complete surrounding wiring in the ground shield region for maximum shielding effect, and simplified wiring in other regions. This segmentation reduces overall complexity while maintaining the necessary ground shield performance.
Data Source
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Figure 2B
AI summary
An electronic device according to various embodiments comprises: a circuit element; a printed circuit board comprising a first connection pad connected to the ground of the electronic device, a second connection pad, and a third connection pad arranged between the first connection pad and the second connection pad and connected to a signal terminal of the circuit element; and a flexible printed circuit board (FPCB) comprising a coupling part connected to the printed circuit board, and a connection part extending from the coupling part, wherein the FPCB comprises first ground wiring connected to the first connection pad and extending from the coupling part to the connection part in an assigned direction, second ground wiring connected to the second connection pad and extending from the coupling part to the connection part in the assigned direction, signal wiring connected to the third connection pad and extending from the coupling part to the connection part in the assigned direction, while being arranged between the first ground wiring and the second ground wiring, and third ground wiring arranged in an opposite direction to the assigned direction so as to be connected, in the coupling part, to the first ground wiring and the second ground wiring and surround the signal wiring. Other various embodiments are possible.