Flexible Circuit Board Floating Pattern Delamination Prevention
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Solution Overview
Problem
Display devices face delamination defects when the flexible circuit board is bent, as the edge without board pads is not evenly distributed by the isotropic conductive film, leading to tensile or compressive stress and potential delamination from the display panel.
Innovation Solution
Incorporating a floating pattern on the flexible circuit board connected to the display panel via an anisotropic conductive film, where the floating pattern is spaced apart from the conductive film and has a specific length and width, allowing even distribution of the adhesive resin and preventing delamination during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flexible circuit board is bent during manufacturing or assembly, then the board can be positioned and connected to the display panel, but the edge without board pads experiences uneven distribution of the anisotropic conductive film, generating tensile or compressive stress that causes delamination
Solution Approach 1:
The patent introduces a floating pattern with specific electrical characteristics (different from board pads) in the edge region without board pads. This creates local quality differentiation where the floating pattern provides electrical connection and stress distribution functionality specifically in the vulnerable edge area, while board pads maintain their primary bonding function. The floating pattern's unique properties address the local problem of uneven ACF distribution and delamination risk at the board edge.
Solution Approach 2:
The floating pattern acts as an intermediary element between the flexible circuit board edge and the display panel. It provides an additional electrical connection path and mechanical anchor point in the region where board pads are absent, mediating the stress and bonding forces that would otherwise cause delamination. The floating pattern transfers and distributes the bonding stress evenly across the edge region.
2Ease of manufacture
If board pads are placed only in specific regions to minimize material usage and cost, then manufacturing cost is reduced, but the edge regions without board pads are prone to delamination when bent
Solution Approach 1:
The patent segments the electrical connection and bonding function into two distinct elements: board pads for primary bonding and signal transmission, and floating patterns for edge region stabilization and additional electrical connection. This segmentation allows board pads to be concentrated in optimal locations for cost efficiency, while floating patterns are strategically placed only in edge regions that require delamination prevention, minimizing overall material usage while ensuring reliability.
Solution Approach 2:
The floating pattern provides localized electrical connection and mechanical support specifically in edge regions where board pads are absent. This local quality enhancement ensures that the critical edge areas have sufficient bonding reliability and stress distribution capability, while the rest of the board maintains cost-effective design with minimal pad placement.
3Adaptability or versatility
If the flexible circuit board is made thinner and more flexible to improve display device design freedom, then adaptability increases, but the board becomes more susceptible to delamination from bending stress
Solution Approach 1:
The floating pattern creates local quality enhancement at the board edge, providing concentrated electrical connection and mechanical anchoring strength precisely where bending-induced delamination risk is highest. This localized reinforcement allows the overall board to remain thin and flexible while the edge region gains enhanced delamination resistance through the floating pattern's bonding capability.
Solution Approach 2:
The floating pattern is pre-configured in the edge region before bonding occurs, establishing a preliminary electrical and mechanical connection path. During the bonding process and subsequent bending operations, this pre-established floating pattern structure proactively prevents delamination by distributing stress evenly, rather than reacting to delamination forces after they occur.
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 solution effectively prevents or suppresses delamination of the flexible circuit board from the display panel, enhancing the reliability of the display device by ensuring even distribution of the adhesive resin during thermal compression.
Implementation Method 1
even distribution of the adhesive resin during thermal compression
Data Source
AI summary
A display device includes: a display panel including a plurality of display pads each extending in a first direction and arranged in a second direction crossing the first direction; a main circuit board; and a flexible circuit board including: board pads connected to the display pads; and a floating pattern spaced apart from the board pads, the floating pattern connected to the display panel by an anisotropic conductive film (ACF), wherein at least a portion of the floating pattern does not overlap with the ACF in plan view.