Flexible Circuit Board Outer Lead Region Area Reduction
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Solution Overview
Problem
The existing flexible circuit boards using COF package technology face challenges in reducing the area of the outer lead region, which increases the bezel size of flat panel displays due to the arrangement of via pads.
Innovation Solution
The flexible circuit board design includes a base film with a defined outer lead region featuring a greater number of first outer leads than second outer leads, with some first outer leads connected to the second wiring pattern through first vias and the remaining extending from the wiring pattern to the outer lead region, while second outer leads are connected through second vias, allowing for a reduced number of second vias in the outer lead region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via pads are arranged in the outer lead region to connect wiring patterns, then electrical connection is achieved, but the area of the outer lead region increases, leading to larger bezel size
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of via pads to a three-dimensional stacked configuration where multiple via pads are arranged vertically at different heights. This dimensional change allows electrical connections to be established without increasing the horizontal footprint of the outer lead region, thereby reducing the bezel size while maintaining connection reliability.
Solution Approach 2:
The patent implements a nested structure where multiple via pads are positioned within each other in the vertical direction, with lower via pads serving as part of the connection path for upper via pads. This nesting approach consolidates multiple connection functions into a compact vertical stack, eliminating the need for lateral expansion of the outer lead region.
2Reliability
If the number of via pads is increased to provide more connection paths, then connection reliability improves, but the outer lead region area increases
Solution Approach 1:
The patent resolves this contradiction by arranging multiple via pads in the vertical dimension rather than spreading them horizontally. Multiple connection paths are achieved by stacking via pads at different heights, allowing increased connection reliability without expanding the outer lead region area.
Solution Approach 2:
The patent utilizes the flexible nature of the circuit board to create a multi-layered structure where via pads are positioned at different vertical levels. This flexibility enables the creation of compact, stacked connection paths that provide multiple connection routes within a minimal footprint.
Data Source
AI summary
A flexible circuit board is provided. The flexible circuit board includes a base film with an outer lead region defined on either one surface or the other surface and an outer lead provided in the outer lead region and connected to an electronic device, in which the outer lead includes a plurality of first outer leads and a plurality of second outer leads formed to be spaced apart from each other so as to face each other in the outer lead region, and in which the number of the plurality of first outer leads is greater than the number of the plurality of second outer leads.