FPC Pad Configuration for Signal Integrity and Welding Flexibility
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Solution Overview
Problem
The design of common connector pads on printed circuit boards (PCBs) is constrained by industry associations, resulting in poor flexibility and capacitance issues that can lead to signal integrity problems due to impedance variations.
Innovation Solution
The proposed solution involves an FPC with a pad configuration that includes at least one signal pad layer and one ground pad layer, where the signal pad area is smaller than the ground pad area. This design optimizes impedance continuity by reducing signal backflow paths and improves the integrity of transmission signals between the PCB and the FPC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pad area is increased to improve welding flexibility, then the ease of manufacture improves, but the capacitance increases which pulls down the impedance and deteriorates signal integrity
Solution Approach 1:
The patent applies local quality by making the signal pad area smaller than the ground pad area. This creates different local characteristics: the signal pad is minimized to reduce capacitance and maintain impedance, while the ground pad is enlarged to provide sufficient grounding and welding flexibility. This asymmetric local quality resolves the contradiction between welding flexibility and signal integrity.
2Reliability
If the signal pad area is made smaller to maintain impedance, then the signal integrity improves, but the welding flexibility deteriorates
Solution Approach 1:
The patent employs asymmetry by creating an unequal relationship between signal pad area and ground pad area. The signal pad is deliberately made smaller to maintain impedance continuity, while the ground pad is made larger to compensate for welding flexibility. This asymmetric design allows each pad type to be optimized for its specific function, resolving the contradiction between signal integrity and welding flexibility.
Data Source
AI summary
Embodiments of the present disclosure disclose a Flexible Printed Circuit (FPC), including: a pad configured to be welded to a Printed Circuit Board (PCB), and the pad includes at least one signal pad layer and at least one ground pad layer, and a signal pad area in the at least one signal pad layer is smaller than a ground pad area in the at least one ground pad layer.