PCB-FPC Interconnect Layout for High-Speed Signal Loss Reduction
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Solution Overview
Problem
The increase in the number of transmission lines in printed circuit boards (PCBs) for high-speed and high-density electronic devices leads to a significant increase in core board quantity, necessitating the use of expensive materials with low dielectric loss, which reduces the cost competitiveness of the devices.
Innovation Solution
Incorporating flexible printed circuits (FPCs) with transmission lines into the PCB design, utilizing core boards with lower dielectric loss for FPCs, and optimizing trace section spacings to reduce transmission loss and crosstalk, while minimizing the number of core boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the quantity of transmission lines in the PCB is increased to improve high-speed performance, then the transmission capability is improved, but the quantity of core boards increases significantly and costs increase
Solution Approach 1:
The patent combines multiple transmission lines onto a single core board by using FPCs with flexible routing capabilities. Instead of requiring separate core boards for each transmission line, the FPC integrates multiple lines (first transmission line, second transmission line, third transmission line) onto one board, reducing the total quantity of core boards while maintaining high-speed transmission capability
Solution Approach 2:
The FPC serves multiple functions: it provides high-speed transmission paths, integrates multiple transmission lines, and reduces the number of core boards required. The first FPC simultaneously handles first transmission lines and second transmission lines, making it a multi-functional component that addresses both performance and cost requirements
2Loss of energy
If expensive materials with low dielectric loss are used for core boards to reduce signal loss, then transmission loss is reduced, but device costs increase significantly
Solution Approach 1:
The patent applies different material qualities to different parts of the system. The FPC uses expensive low-dielectric-loss materials for its core board to minimize signal loss in critical high-speed paths, while the main PCB can use more cost-effective materials. This localized application of high-performance materials reduces overall device cost while maintaining signal integrity where it matters most
Solution Approach 2:
The FPC with its expensive low-dielectric-loss core board can be treated as a specialized, potentially replaceable component. By concentrating the expensive materials in the FPC rather than throughout the entire PCB assembly, the system allows for cost optimization where the expensive FPC can be manufactured in smaller quantities or replaced more easily if needed
3Productivity
If the quantity of core boards in the PCB is increased to accommodate more transmission lines, then transmission line capacity increases, but cost competitiveness decreases
Solution Approach 1:
The patent merges multiple transmission line functions into the FPC structure. The first FPC integrates first transmission lines and second transmission lines onto a single core board, and the second FPC integrates third transmission lines and fourth transmission lines. This merging approach increases transmission line capacity without proportionally increasing the number of core boards, thereby maintaining cost competitiveness
Data Source
Figure 1-1~2-1
Figure 2-2~3-1
Figure 3-2
AI summary
This application provides a circuit board and an electronic device. In addition to a PCB, the circuit board may further include an FPC assembled on the PCB. In addition, a line between different components assembled on the PCB includes a line in the PCB, and further includes a line in the FPC. Because a quantity of core boards in the FPC is generally far less than a quantity of core boards in the PCB, selecting a core board with a dielectric loss less than that of the PCB for the FPC helps reduce a transmission loss of a high-speed signal in the circuit board, and helps reduce costs of the circuit board. This application further provides an electronic device. Selecting, for the electronic device, the circuit board provided in this application helps improve cost competitiveness of the electronic device in a high-speed high-density scenario.