Flexible Circuit Board Bending Durability via Protective Film
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Solution Overview
Problem
Traditional flexible circuit boards are prone to damage and signal transmission efficiency is compromised due to repeated bending, especially when using coaxial cables, which also restricts their placement within wireless terminals due to impedance issues.
Innovation Solution
A method of manufacturing flexible circuit boards with enhanced bending durability involves forming specific dielectric layers and ground structures, using bonding and protective sheets to create a stepped structure that allows for flexible placement without signal line or ground damage, and includes via holes for electrical connection, preventing carbide formation during cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the dielectric is cut to reduce thickness for bending durability, then bending durability is improved, but signal line and ground surface are damaged and signal transmission efficiency is lowered
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the dielectric layer before cutting. This protective film prevents damage to the signal line and ground surface during the cutting process, allowing the dielectric to be thinned without compromising signal transmission efficiency. The protective film is formed in advance to prevent the harmful effect of cutting damage.
Solution Approach 2:
The patent uses a protective film as an intermediary substance between the cutting tool and the signal line/ground surface. This intermediary layer allows the cutting operation to proceed while preventing direct contact and damage between the cutting blade and the electrical conductors, thus maintaining signal transmission efficiency while achieving thickness reduction for improved bending durability.
2Manufacturing precision
If laser beam is used to cut the dielectric, then cutting precision is improved, but carbide is formed on signal line and ground causing electrical connection or reduced signal transmission efficiency
Solution Approach 1:
The protective film serves as an intermediary that absorbs or deflects the laser beam's harmful effects. When the laser beam cuts the dielectric, the protective film prevents direct heating and carbide formation on the signal line and ground surface, allowing precise cutting without the harmful side effect of carbide deposition that would compromise electrical performance.
Solution Approach 2:
The patent converts the potentially harmful laser beam into a beneficial cutting tool by using the protective film to manage its effects. The laser beam's high energy is directed to cut the dielectric precisely, while the protective film captures any excess energy that would otherwise create carbide, thus transforming a harmful process into a beneficial one.
3Reliability
If the flexible circuit board is placed near other components for impedance matching, then signal transmission efficiency is improved, but the shape and location must be changed according to component variations reducing installation flexibility
Solution Approach 1:
The patent applies local quality by creating a localized controlled impedance environment through the protective film and ground structure design. This allows the flexible circuit board to maintain proper impedance characteristics at specific signal transmission locations while remaining flexible in overall placement and configuration, thus achieving both signal transmission efficiency and installation flexibility.
Data Source
AI summary
A flexible circuit board having enhanced bending durability and a method for preparing same are provided. The method comprises: forming a signal line and a first ground layer on a first dielectric body and forming a second ground layer on a bottom side of the first dielectric body; preparing a second dielectric body; preparing a first bonding sheet and a first protective sheet which is connected to one end of the first bonding sheet or of which one or more parts are overlapped on one end of the first bonding sheet; bonding the second dielectric body onto the first dielectric body by means of the first bonding sheet; forming a via hole such that the first ground layer and the second ground layer are conducted; and cutting in a width direction the second dielectric body placed on the first protective sheet.