Flexible PCB Mesh Ground Layer Design for Pleated Bending
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Solution Overview
Problem
Flexible printed circuit boards with solid GND outer layers are hard and difficult to mold into pleated shapes, leading to high bending stress and frequent disconnection during extension/contraction, which increases maintenance costs and disrupts production.
Innovation Solution
A flexible printed circuit board design featuring a strip line transmission path with insulating layers made of thermoplastic resin, where mesh ground layers are on the outer peripheral side and solid ground layers are on the inner peripheral side of curved portions, reducing bending stress and preventing disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid GND outer layers are used in flexible printed circuit boards, then electrical shielding and signal stability are improved, but the board becomes hard and difficult to mold into pleated shapes, increasing bending stress and causing frequent disconnection
Solution Approach 1:
The patent applies different ground layer configurations to different regions of the flexible printed circuit board. Solid ground layers are used in regions requiring electrical shielding, while mesh ground layers are used in pleated curved portions requiring flexibility. This local differentiation resolves the contradiction by providing solid GND where needed for signal stability while using mesh GND where needed for moldability and reduced bending stress.
2Ease of manufacture
If mesh ground layers are used on the outer peripheral side of curved portions, then flexibility and ease of molding are improved, but electrical shielding effectiveness may be reduced
Solution Approach 1:
The patent strategically places mesh ground layers on the outer peripheral side of curved portions where flexibility is needed, while maintaining solid ground layers in other areas where electrical shielding is critical. This local quality approach ensures that the mesh structure provides the necessary flexibility without compromising overall shielding effectiveness.
Solution Approach 2:
The flexible printed circuit board uses a composite structure combining mesh ground layers and solid ground layers in different regions. This composite approach allows the board to simultaneously achieve flexibility in curved portions through mesh structures and effective electrical shielding through solid ground layers in other areas.
3Reliability
If solid ground layers are used throughout the board, then electrical shielding is improved, but bending stress during extension/contraction increases, leading to frequent disconnection
Solution Approach 1:
The patent reduces bending stress by implementing mesh ground layers specifically in pleated curved portions where flexibility is required, while maintaining solid ground layers in regions where electrical shielding is prioritized. This local differentiation resolves the contradiction by providing mesh structures where bending resistance needs to be reduced and solid structures where electrical shielding needs to be maintained.
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 design prevents disconnection during repeated extension/contraction while maintaining electrical characteristics, reducing maintenance costs and ensuring continuous production.
Implementation Method 1
insulating layers covering the signal line from both sides and each made of a thermoplastic resin as its material
Data Source
AI summary
A flexible printed circuit board having at least a set of strip line transmission path by being provided with a signal line, and a pair of ground layers and, includes a pleated part PL having a plurality of curved portions which are curved so as to be opened or closed, in which in the ground layers, mesh ground layers in which conductive portions are provided in a mesh shape, and solid ground layers in which the conductive portions are provided in a planar state, are provided, in which the mesh ground layers are arranged on an outer peripheral side of the curved portions PL2, and the solid ground layers are arranged on an inner peripheral side of the curved portions.