PCB Substrate Spacing via Through-Hole FPC Routing
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Solution Overview
Problem
Conventional printed circuit boards (PCBs) face challenges with impedance mismatching due to the length of flexible printed circuits (FPCs) projected from edge portions, leading to signal distortion and setup/hold failures, especially when the FPC length increases.
Innovation Solution
A PCB design with substrates spaced apart using a signal transmission element, such as a flexible printed circuit, that is extended through an opening in the substrate, reducing the FPC length and minimizing impedance mismatching by forming the signal transmission element with pattern layers and using insulation jigs for isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the FPC is projected from edge portions to connect substrates, then the substrates can be connected with flexibility, but the FPC length increases causing impedance mismatching and signal distortion
Solution Approach 1:
The FPC is extended through an opening in the substrate rather than from the edge, changing the spatial dimension of connection. This allows the FPC to pass through the substrate thickness direction, reducing the horizontal length required for connection while maintaining flexibility.
Solution Approach 2:
An opening is created in the substrate to serve as an intermediary pathway for the FPC. This opening acts as a mediator that allows the FPC to pass through the substrate, reducing the need for long external connections and minimizing impedance mismatching.
2Length of stationary object
If the FPC length is increased to connect spaced substrates, then the substrates can be disposed at greater distances, but impedance mismatching and signal distortion increase
Solution Approach 1:
Instead of increasing horizontal distance, the solution utilizes the vertical dimension by extending the FPC through openings in both substrates. This allows substrates to be spaced apart while keeping the FPC path compact and controlled, preventing signal degradation.
Solution Approach 2:
The FPC extension through openings changes the geometric parameters of the connection path. By controlling the position and size of openings, the FPC length and impedance characteristics can be optimized to maintain signal quality while allowing substrate spacing.
3Length of moving object
If the FPC is extended through an opening in the substrate, then the FPC length is reduced and impedance mismatching is minimized, but the substrate structure becomes more complex
Solution Approach 1:
The substrate is segmented by creating openings that divide the substrate structure into regions. These openings are strategically placed to allow FPC passage while maintaining the overall structural integrity and functionality of the substrate.
Solution Approach 2:
The opening structure adds a vertical dimension element to the substrate, transforming it from a flat surface to a three-dimensional structure with through-holes. This dimensional change enables compact FPC routing while maintaining substrate strength through proper opening design.
Data Source
AI summary
An improved printed circuit board (PCB) includes first and second substrates, which are disposed being distanced or spaced mutually and in which at least one or more semiconductor chips are mounted, and a signal transmission part for providing a signal transmission path between the first and second substrates, the signal transmission part being extended out of a region having a size smaller than a maximum size of the first substrate within the first substrate, and being extended in the second substrate. In disposing two substrates in a spaced-apart structure of upper and lower positions, a length of flexible printed circuit (FPC) connecting the two substrates can be reduced, and an impedance mismatching caused in use of the FPC can be reduced.