Flexible Printed Circuit Board Breakage Detection Mechanism
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Solution Overview
Problem
Flexible printed circuit boards are prone to breakage when subjected to external forces, leading to conduction failures and potential damage to electronic devices, as existing reinforcement techniques compromise flexibility and increase rigidity.
Innovation Solution
Incorporating a breakage detection portion with no signal wires and a through hole adjacent to the signal wiring portion, which breaks first under stress, preventing signal wire cutoff and allowing for user notification of external force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dummy wires are formed in curved portions and side edges to improve strength, then the strength of the resin base material is improved, but the flexibility of the flexible printed circuit board is compromised and rigidity increases
Solution Approach 1:
The invention applies local quality by forming dummy wires specifically in curved portions and side edges where strength is needed, while leaving the central signal transmission areas without dummy wires to maintain flexibility. This localized application of reinforcement resolves the contradiction by providing strength only where structurally necessary.
Solution Approach 2:
The flexible printed circuit board is segmented into different functional zones: curved portions and side edges contain dummy wires for strength, while central portions maintain pure signal transmission layers for flexibility. This segmentation allows different regions to have optimized properties for their specific functions.
2Length of moving object
If the flexible printed circuit board is made thinner to enable miniaturization, then the size is reduced, but the board becomes more susceptible to breakage
Solution Approach 1:
The invention maintains thin overall thickness while locally adding dummy wires in curved portions and side edges to provide breakage resistance where stress concentrates, without increasing the thickness of the entire board or compromising miniaturization.
3Strength
If a thick film member is added to provide sufficient strength, then the strength is improved, but the rigidity increases and flexibility is compromised
Solution Approach 1:
Instead of adding a thick film member across the entire board, the invention locally forms dummy wires only in curved portions and side edges, providing necessary strength without the rigidity increase that would result from full-coverage thick film addition.
Data Source
AI summary
A flexible printed circuit board can prevent itself from breaking without losing its flexibility, avoid significantly damaging the operation of an electronic device in the event that a part of the flexible printed circuit board is broken, and warn the user about the occurrence of a breakage. The flexible printed circuit board includes: a connecting portion that is formed at an end of a signal wire for transmitting an electric signal; a signal wiring portion in which a plurality of unidirectionally aligned signal wires are disposed in a vicinity of the connecting portion; a breakage detection portion in which the signal wires are not disposed and that is formed at one of side edges of the signal wiring portion; and a through hole formed between the breakage detection portion and the signal wiring portion.