Flexible PCB Differential Stub Layout for Crosstalk Reduction

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Solution Overview

Problem

The use of a mesh ground in flexible printed circuit boards leads to reduced grounding area and degraded signal quality due to discontinuity, while adding guard traces to mitigate cross-talks further increases board width and decreases flexibility, compromising the spatial utility of electronic devices.

Innovation Solution

The flexible printed circuit board design incorporates first and second transmission lines with stubs protruding perpendicularly and aligned stubs on opposite directions to reduce cross-talks, enhancing signal quality and flexibility without increasing width.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flexible printed circuit board is disposed between a housing and a back cover, then connection between components is improved, but the assembly process becomes complex and time-consuming

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The flexible printed circuit board is pre-assembled with the battery in a battery pack assembly before being integrated into the housing. This preliminary assembly reduces the complexity and time of the final assembly process, as the FPCB connection is already prepared and tested before housing assembly.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a flexible printed circuit board is disposed between a housing and a back cover, then connection between components is improved, but the number of assembly steps increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The device is divided into modular assemblies: the battery pack (containing the battery and FPCB), the housing, and the back cover. This segmentation allows each module to be assembled and tested independently, reducing the overall assembly process complexity while maintaining reliable connections through standardized interfaces.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If the flexible printed circuit board extends along a curvature, then adaptability to device shape is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveshape adaptabilityVSAvoidcurvature alignment precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The flexible printed circuit board is designed as a thin, flexible film that can conform to curved surfaces. This flexibility allows the FPCB to adapt to the device's shape requirements while maintaining electrical connections, reducing the need for high-precision rigid mounting structures.

Inventive Principle:
Principle #30Flexible shells and thin films

Data Source

PatentEP4216681B1Electronic device comprising flexible printed circuit board
Publication Date: 2026.04.22 SAMSUNG ELECTRONICS CO LTD
  • EP4216681B1 patent drawingFigure 1
  • EP4216681B1 patent drawingFigure 2
  • EP4216681B1 patent drawingFigure 3

AI summary

Disclosed are a flexible printed circuit board and an electronic device comprising the flexible printed circuit board. The flexible printed circuit board of the electronic device may comprise: a first dielectric layer; a first differential line which is disposed on a first surface of the first dielectric layer and which includes a first transmission line and a second transmission line; and a first mesh ground disposed on a second surface of the first dielectric layer. The first transmission line includes first stubs, which are disposed in the longitudinal direction of the first transmission line and protrude in a first direction that is substantially perpendicular to the longitudinal direction of the first transmission line, and second stubs, which are disposed in the longitudinal direction of the first transmission line and protrude in a second direction opposite to the first direction, and the second transmission line may include third stubs, which are disposed in the longitudinal direction of the second transmission line and protrude in the first direction, and fourth stubs, which are disposed in the longitudinal direction of the second transmission line and protrude in the second direction. Other various embodiments identified through the specification are possible.