Rigid-Flex PCB Impedance Control via Shielding Layer
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Solution Overview
Problem
Conventional rigid and flexible printed circuit boards fail to effectively control impedance for high-frequency signal transmission, leading to signal distortion and errors, particularly in differential mode signal lines due to material characteristics and environmental factors.
Innovation Solution
A rigid-flexible circuit board structure with a shielding layer on the flexible circuit board's insulation layer, electrically connected to a grounding section of a rigid circuit board, incorporates an impedance control structure to manage the impedance of differential mode signal lines, ensuring accurate signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rigid or flexible printed circuit boards are used for high-frequency signal transmission, then the circuit board can be manufactured and assembled, but signal transmission errors and distortions occur due to poor impedance control
Solution Approach 1:
The patent applies local quality by creating a dedicated impedance control structure with specific geometric features (width, spacing, positioning) in the signal transmission path. This localized structural design ensures that the differential mode signal lines maintain controlled impedance characteristics at critical sections, thereby improving signal transmission reliability without requiring entire circuit board redesign
Solution Approach 2:
The patent introduces an intermediary impedance control structure that mediates between the signal source and the flexible circuit board. This intermediate structure acts as a buffer to manage impedance transitions and reduce signal reflections, thereby improving signal integrity while maintaining manufacturing feasibility
2Adaptability or versatility
If flexible circuit board material is used to achieve flexibility and bending capability, then adaptability is improved, but impedance control deteriorates due to material characteristics and environmental factors
Solution Approach 1:
The patent applies local quality by creating a dedicated impedance control structure with specific geometric features (width, spacing, positioning) in the signal transmission path. This localized structural design ensures that the differential mode signal lines maintain controlled impedance characteristics at critical sections, thereby improving signal transmission reliability without requiring entire circuit board redesign
Solution Approach 2:
The patent addresses the dynamic nature of flexible circuit boards by designing the impedance control structure to accommodate bending and deformation. The structure maintains its impedance control function even when the flexible circuit board is bent, allowing the system to adapt to different configurations while preserving signal integrity
Data Source
AI summary
A rigid-flexible circuit board includes at least one flexible circuit board and at least one rigid circuit board. The flexible circuit board includes a flexible-board substrate, a plurality of flexible circuit board differential mode signal lines, at least one flexible circuit board grounding line, a flexible circuit board insulation layer formed on the upper surface of the flexible-board substrate and covering the flexible circuit board differential mode signal lines and the flexible circuit board grounding line. The rigid circuit board is stacked on the stacking section of the flexible circuit board. A shielding layer is formed on the flexible circuit board insulation layer of the flexible circuit board and corresponds to the extension section of the flexible circuit board. The shielding layer further extends from the extension section to the stacking section. An impedance control structure is formed on the shielding layer to control the impedance of the flexible circuit board differential mode signal lines.