Flexible Printed Circuit Board Loop Design for Noise Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In portable information equipment like laptops, the flexible printed-circuit board used to transfer signals between the main body and display units experiences increased radiation noise due to its loop configuration around the hinge, which also absorbs expansion and contraction, leading to longer signal wiring lengths and heightened noise emission.
Innovation Solution
The flexible printed-circuit board features a pattern of discontinuous conductor layers on the inward-bending area, electrically connected through holes to the ground lines on the first surface, with varying intervals and widths to absorb stress and disperse bending, while maintaining bendability and reducing radiation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the flexible printed-circuit board is configured as a loop around the hinge to absorb expansion and contraction, then the bendability and flexibility are improved, but the radiation noise from signal wirings increases due to longer wiring length
Solution Approach 1:
The conductor layer is divided into multiple separate conductor patterns in the loop formation region rather than being continuous. These segmented conductor patterns are electrically connected through holes, creating discrete noise radiation paths that reduce overall radiation noise while preserving the loop's flexibility and bendability
Solution Approach 2:
The cover film is selectively removed only in specific regions where conductor patterns are present, creating local differences in structure. This localized modification allows the conductor patterns to be electrically connected while maintaining the loop configuration, reducing radiation noise without compromising flexibility
2Adaptability or versatility
If the flexible printed-circuit board uses a loop configuration to absorb stress from opening and closing, then the flexibility is improved, but the wiring length increases causing increased radiation noise
Solution Approach 1:
By segmenting the conductor layer into separate patterns connected through holes, the effective electrical path length is reduced compared to a continuous conductor layer, thereby reducing radiation noise while maintaining the loop's flexibility and stress-absorbing capability
Data Source
AI summary
According to the invention, information processing equipment using a flexible printed-circuit board which does not lose bendability with repeated opening and closing of a display unit, and which suppresses radiation noise from signal wiring is provided. In the configuration of the invention, a first cover film is formed to cover a wiring layer on a first surface of a base film, and a second cover film is formed to cover a wiring layer on a second surface of the base film. Portions of the second cover film and the underlying wiring layer on the second surface in the loop formation region are discontinuously removed in the inward-bending area of the loop, and the base film is exposed in the removed parts. The wiring layer underneath the remaining second cover film, which is not removed, and the wiring layer on the first surface of the base film are electrically connected via through holes penetrating the base film.