Flexible Circuit Board Isolation Line for Copper Ion Migration
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Solution Overview
Problem
Flexible circuit boards in display devices experience undesirable phenomena such as insulating layer burn-out due to copper ion migration between adjacent high and low voltage signal lines, leading to electrochemical corrosion and signal failure, especially in high temperature and high humidity environments.
Innovation Solution
Incorporating an isolation protecting line between adjacent voltage signal lines on the flexible circuit board, which is not electrically connected or grounded, to prevent copper ion migration and serve as a barrier against electrochemical corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If adjacent high and low voltage signal lines are arranged close to each other to reduce circuit board area, then area utilization is improved, but copper ion migration occurs causing insulating layer burn-out
Solution Approach 1:
The patent introduces an isolation protecting line that segments the space between adjacent voltage signal lines. This segmentation creates separate isolated regions for high and low voltage signals, preventing copper ion migration between them while maintaining compact layout. The isolation protecting line acts as a physical and electrical barrier that divides the potentially harmful interaction zone into distinct segments.
Solution Approach 2:
The isolation protecting line serves as an intermediary element between adjacent voltage signal lines. It is positioned between the high and low voltage lines and configured to be not electrically connected or grounded, creating an intermediate zone that blocks copper ion migration pathways. This intermediary structure prevents direct interaction between the voltage lines while maintaining spatial proximity for area efficiency.
2Reliability
If isolation protecting line is added between adjacent voltage signal lines to prevent copper ion migration, then reliability is improved, but device complexity increases
Solution Approach 1:
The isolation protecting line is merged with the existing signal line structure and manufactured using the same conductive layer materials and processes. By combining the isolation function with the existing circuit board fabrication workflow, the patent minimizes additional complexity while achieving reliable copper ion migration prevention. The isolation line uses identical material layers (conductive layer, insulating layer, flat layer, electrode layer) as the signal lines.
Solution Approach 2:
The patent changes the electrical state parameter of the isolation protecting line by configuring it to be not electrically connected or grounded, unlike traditional signal lines. This parameter change allows the same physical structure to serve dual purposes: maintaining structural integrity with signal lines while providing isolation functionality through its unique electrical configuration, thereby reducing complexity.
3Object-affected harmful factors
If copper ions migrate between adjacent voltage signal lines in high temperature and humidity environments, then electrochemical corrosion occurs, but signal transmission fails
Solution Approach 1:
The isolation protecting line is configured in advance to prevent copper ion migration before electrochemical corrosion can occur. By establishing the isolation barrier during manufacturing with the line configured to be not electrically connected or grounded, the patent proactively blocks the copper ion migration pathway that would otherwise be accelerated by high temperature and humidity environments, preventing signal transmission failure before it happens.
Data Source
AI summary
A flexible circuit board, a method for manufacturing the flexible circuit board, and a display device are provided. The flexible circuit board includes: a plurality of driving signal lines arranged with mutually insulate-gates, wherein the driving signal lines comprise at least two voltage signal lines arranged adjacent to each other; at least one isolation protecting line, the isolation protecting line being located between the two voltage signal lines arranged adjacent to each other.