Flexible Flat Cable Resonance Prevention via Ground Line Extraction
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Solution Overview
Problem
Flexible Flat Cables (FFCs) with coplanar transmission lines experience resonance due to multiple reflection, degrading transmission quality, and existing solutions like connecting ground lines via a shield layer complicate the manufacturing process, increasing costs.
Innovation Solution
Configuring the transmission line as a microstrip or strip transmission line by omitting ground lines and using a connector with a ground member to connect the shield layer with a mating ground terminal, preventing resonance while simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground lines are connected via a shield layer to prevent resonance, then transmission quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts and removes the ground lines from the FFC structure, configuring the transmission line as a microstrip or strip transmission line without ground lines. This eliminates the need for complex shield layer connections while preventing resonance through the inherent structure of the simplified transmission line configuration.
Solution Approach 2:
Instead of adding ground lines and shield layers to prevent resonance (conventional approach), the invention inverts the approach by omitting ground lines entirely and using the connector's ground member to achieve resonance prevention. This reverse thinking simplifies the FFC structure while maintaining transmission quality.
2Reliability
If ground lines are connected via a shield layer to prevent resonance, then transmission quality is improved, but manufacturing cost increases
Solution Approach 1:
The invention extracts and removes the ground lines from the FFC structure, configuring the transmission line as a microstrip or strip transmission line without ground lines. This eliminates the need for complex shield layer connections while preventing resonance through the inherent structure of the simplified transmission line configuration.
Solution Approach 2:
The invention uses a simple ground member in the connector that provides the necessary grounding function without requiring expensive and complex shield layer structures. The ground member achieves the same resonance prevention effect at lower manufacturing cost.
3Device complexity
If ground lines are omitted to simplify manufacturing, then manufacturing complexity is reduced, but resonance prevention capability is lost
Solution Approach 1:
The invention moves the grounding function from the FFC structure itself to the connector structure. By placing the ground member in the connector rather than in the FFC, the solution achieves resonance prevention in a different dimensional approach, simplifying FFC manufacturing while maintaining reliability.
Solution Approach 2:
The ground member in the connector acts as an intermediary that provides the grounding function necessary for resonance prevention. Instead of requiring ground lines within the FFC, the ground member mediates the connection between the signal lines and ground potential, achieving the same effect through a different mechanism.
Data Source
AI summary
A connecting object is used for connection to a device. The connecting object has a sheet-like shape. The device has at least two ground pins and at least one signal pin. The at least one signal pin is arranged between two of the ground pins in a pitch direction. The connecting object has a wiring layer, a shield layer and an insulator. The wiring layer is formed with only a signal line which is configured to be connected with the signal pin. The wiring layer is formed with no ground line which is configured to be connected with the ground pin. The shield layer covers the wiring layer via the insulator which is positioned between the shield layer and the wiring layer.