Flexible PCB Shielding via Segmented Via Walls
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Solution Overview
Problem
The challenge is to create a printed circuit board that minimizes data loss during high-frequency signal transmission while maintaining flexibility and durability, particularly for applications like foldable mobile devices where repeated bending and folding are required, and existing designs often suffer from pattern crack defects due to external forces.
Innovation Solution
The solution involves a printed circuit board structure with a first and second insulating layer, a first conductive shield wall spaced apart from the sides of the wiring line, and a second conductive shield wall spaced apart from the ends, featuring via walls that extend in the thickness direction with gaps to control signal radiation and enhance flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of internal components is reduced to achieve miniaturization and slimming, then the overall thickness and weight are reduced, but pattern crack defects occur under repeated external force
Solution Approach 1:
The patent uses a composite structure combining rigid and flexible regions in the printed circuit board. The rigid region provides structural strength to prevent cracking, while the flexible region allows bending and folding. This composite approach resolves the contradiction by integrating materials with different mechanical properties into a single functional unit that simultaneously achieves thinness and durability.
Solution Approach 2:
The printed circuit board is divided into distinct rigid and flexible regions. The rigid region contains the wiring lines and shield walls for signal transmission, while the flexible region accommodates bending and folding. This segmentation allows each region to optimize its function - the rigid part maintains structural integrity while the flexible part provides bendability, resolving the thickness-durability contradiction.
2Object-affected harmful factors
If a continuous conductive shield wall is used to prevent signal radiation, then electromagnetic shielding effectiveness is improved, but flexibility and bendability are reduced
Solution Approach 1:
The conductive shield wall is segmented into multiple discrete conductive patterns rather than being continuous. These segmented shield walls are positioned in the rigid region and connected through the flexible region without forming a continuous barrier. This segmentation maintains electromagnetic shielding effectiveness in the signal transmission area while allowing the flexible region to bend without restriction.
Solution Approach 2:
The shield wall structure is designed with different properties in different regions: in the rigid region, conductive patterns provide electromagnetic shielding, while in the flexible region, the absence of continuous conductive structures maintains bendability. This local differentiation resolves the contradiction between shielding effectiveness and flexibility.
3Loss of information
If coaxial cables are used for high-frequency signal transmission, then signal transmission quality is improved, but device volume and weight increase
Solution Approach 1:
The patent replaces the mechanical coaxial cable structure with a planar printed circuit board implementation. The wiring lines are formed as conductive patterns on the PCB substrate, and the shield walls are created as conductive traces or plated structures. This substitution eliminates the need for bulky coaxial cables while maintaining signal transmission quality through careful impedance control and shielding design.
Solution Approach 2:
The three-dimensional coaxial cable structure is transformed into a two-dimensional planar structure on the printed circuit board. The signal transmission function is achieved through conductive patterns etched on the PCB surface, and shielding is provided by conductive walls formed in the same plane. This dimensional transformation significantly reduces volume while maintaining electrical performance.
Data Source
AI summary
A printed circuit board, includes: a first insulating layer on which a wiring line is disposed; a second insulating layer covering an upper portion of the wiring line; a first conductive shield wall spaced apart from two opposing sides of the wiring line in a width direction of the wiring line, and extending in a length direction of the wiring line; and a second conductive shield wall spaced apart from two opposing ends of the first conductive shield wall in the length direction, and extending the a width direction. At least one of the first conductive shield wall or the second conductive shield wall includes a plurality of via walls each extending in a thickness direction of the first insulating layer and the second insulating layer and having a gap is disposed therebetween.