PCB-FPC High-Frequency Interconnect Layout for Crosstalk Suppression
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Solution Overview
Problem
The connecting portion between a printed circuit board and a flexible circuit board struggles to effectively absorb radio waves, leading to potential leakage and crosstalk due to the arrangement of pads, which hinders efficient signal transmission.
Innovation Solution
The implementation of a high-frequency circuit design that includes a printed circuit board with ground conductors and signal lines, and a flexible circuit board with ground conductors and signal lines, where connecting conductors are used to connect the signal lines in a non-conductive state with the ground conductors, reducing electric field leakage and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radio wave absorbing layer is added to reduce crosstalk, then signal transmission quality improves, but the connecting portion between printed circuit board and flexible circuit board cannot effectively include the absorbing layer due to pad arrangement, leading to electric field leakage
Solution Approach 1:
The patent introduces an intermediary structure (the connecting portion with specifically designed pad arrangement and grounding) between the printed circuit board and flexible circuit board to mediate the electromagnetic field distribution, preventing direct leakage while maintaining signal integrity without requiring a separate absorbing layer in the connecting region
Solution Approach 2:
The patent applies local quality by creating region-specific electromagnetic shielding through strategic placement of ground pads and signal pads in the connecting portion, where different areas have different grounding configurations to locally control electric field distribution and prevent leakage without uniformly complicating the entire connecting structure
2Ease of manufacture
If pads are arranged for connecting printed circuit board and flexible circuit board, then electrical connection is achieved, but radio wave absorption is insufficient leading to crosstalk
Solution Approach 1:
The patent implements equipotentiality by connecting multiple ground pads to a common ground potential through the grounding layer, creating an equipotential reference plane that stabilizes the electromagnetic environment and prevents crosstalk between signal lines during the connection between printed and flexible circuit boards
Data Source
AI summary
A high-frequency circuit is configured so as to include a printed circuit board and a flexible circuit board connected to the printed circuit board, wherein the printed circuit board includes: a first dielectric layer having a first surface and a second surface, a first ground conductor being formed on the first surface; a second dielectric layer having a third surface and a fourth surface, a second ground conductor being formed on the fourth surface; and first signal lines wired between the second surface and the third surface, the flexible circuit board includes: a third dielectric layer having a fifth surface and a sixth surface, a third ground conductor being formed on the fifth surface; a fourth dielectric layer having a seventh surface and an eighth surface, a fourth ground conductor being formed on the eighth surface; and second signal lines wired between the sixth surface and the seventh surface.