FPCB Shield Layer Layout for Connector EMI and Short Prevention
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Solution Overview
Problem
Mobile terminals experience noise-induced deterioration in radiation performance due to high-speed signals flowing through flexible printed circuit boards (FPCBs), and existing electromagnetic interference (EMI) shield layers are inadequate, especially at connector connections, leading to potential electrical shorts.
Innovation Solution
A flexible printed circuit board (FPCB) design with conductive layers and shield layers configured to extend up to connector ends, preventing noise induction and electrical shorts, while maintaining assembly flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate laminated tape is used for shielding instead of an EMI shield layer, then shielding is possible, but the shielding performance deteriorates and varies based on attachment deviation
Solution Approach 1:
The patent integrates the EMI shield layer directly into the FPCB structure by forming conductive patterns on the same substrate, merging the shielding function with the circuit board itself. This eliminates the need for separate laminated tapes and their associated attachment deviation issues, providing consistent shielding performance.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the conductive patterns and the terminal portion, mediating the shielding effect while preventing electrical shorts. This intermediary structure ensures reliable EMI shielding without requiring precise external tape attachment.
2Object-affected harmful factors
If an EMI shield layer is provided in a partial area of the FPCB, then some noise reduction is achieved, but it is difficult to provide shielding up to the connector connection portion
Solution Approach 1:
The patent applies local quality by providing the EMI shield layer selectively in specific areas of the FPCB where noise protection is needed, while maintaining openness or different structure near the connector portion. This localized shielding approach reduces signal noise in critical areas without interfering with connector operations.
Solution Approach 2:
The patent segments the FPCB structure into different functional zones: a shielded area with conductive patterns for noise reduction, and an unshielded or differently structured area near the connector for easy connection. This segmentation allows simultaneous achievement of noise reduction and connector accessibility.
3Speed
If high-speed signals are transmitted through the FPCB to ensure assembly flexibility, then data transmission capability is improved, but noise induced in the FPCB causes deterioration in radiation performance
Solution Approach 1:
The patent converts the harmful electromagnetic noise generated by high-speed signals into a beneficial shielding effect by using the same conductive structures to create EMI shields. The conductive patterns that carry high-speed signals are configured to also provide electromagnetic shielding, turning the noise-source into a noise-protection mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The FPCB design effectively shields electromagnetic interference and prevents electrical shorts, enhancing signal integrity and radiation performance in high-speed signal transmission.
Implementation Method 1
a first shield layer disposed in a first direction of the first conductive layer and disposed to at least partially overlap the terminal portion, and a second shield layer disposed in a second direction of the second conductive layer
Data Source
AI summary
A circuit board electrically connected to an electronic device includes a base layer, a first conductive layer on a first surface of the base layer, a second conductive layer on a second surface of the base layer and including a terminal portion which is exposed outside of the circuit board and at which the circuit board is electrically connected to the electronic device, a first electromagnetic shield layer which faces the base layer with the first conductive layer therebetween and overlaps the terminal portion of the second conductive layer and a second electromagnetic shield layer which faces the base layer with the second conductive layer therebetween, and is spaced apart from the terminal portion of the second conductive layer in a direction along the base layer.