Chip-on-Film Dummy Patterns for Repairable Display Bonding
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Solution Overview
Problem
In flat panel display devices, the alignment inaccuracies during the repair process can lead to electric lines being torn due to the adhesive used in the chip-on-film (COF) method, resulting in non-reusable display panels.
Innovation Solution
Incorporating anisotropic conductive film (ACF) with dummy patterns between film lines on the COF, which reduces the bonding force and prevents signal lines from being torn during the repair process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the chip-on-film is bonded to the display panel using adhesive material, then the bonding strength is improved, but the signal lines may be torn during repair process
Solution Approach 1:
The patent introduces dummy patterns that segment the bonding area into functional regions (signal line bonding regions and dummy pattern regions). This segmentation allows the adhesive to be distributed differently across the bonding area, providing strong bonding where needed while creating release zones during repair processes.
Solution Approach 2:
The dummy patterns create local variations in bonding quality across the chip-on-film structure. The areas with dummy patterns have different adhesive distribution and bonding characteristics compared to areas without dummy patterns, enabling localized control over bonding strength to prevent signal line damage during repair.
2Manufacturing precision
If alignment is not accurate during bonding, then the bonding precision deteriorates, but repair process can correct the alignment
Solution Approach 1:
The dummy patterns are pre-configured on the chip-on-film before bonding, providing reference markers and controlled adhesive distribution zones that facilitate alignment during both initial bonding and subsequent repair processes. This preliminary structuring makes alignment correction more manageable.
Solution Approach 2:
The dummy patterns act as intermediary elements between the chip-on-film and the display panel during repair. They provide a controlled interface that allows for alignment adjustment while maintaining overall bonding integrity, serving as a mediator between the need for precision and the need for repairability.
3Stability of the object's composition
If the adhesive material is applied uniformly, then the bonding consistency is improved, but the signal lines are more susceptible to tearing during repair
Solution Approach 1:
The dummy patterns create local variations in adhesive distribution and bonding characteristics. Areas with dummy patterns have modified bonding properties that prevent excessive adhesive force from damaging signal lines during repair, while maintaining overall bonding consistency across the chip-on-film structure.
Solution Approach 2:
The dummy patterns convert the potentially harmful uniform adhesive force into a beneficial distributed bonding pattern. The adhesive material that would otherwise uniformly stress signal lines is redistributed through the dummy pattern regions, creating controlled stress distribution that protects signal lines while maintaining bonding consistency.
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 dummy patterns effectively reduce the bonding force between the COF and the display panel, allowing for accurate realignment and repair without damaging the signal lines, thereby increasing the yield and reliability of the display device.
Implementation Method 1
Incorporating anisotropic conductive film (ACF) with dummy patterns between film lines on the COF, which reduces the bonding force and prevents signal lines from being torn during the repair process
Data Source
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AI summary
A display device includes a display panel and a chip-on-film (COF) bonded to the display panel. The chip-on-film includes a film (262) on which a driving chip (266) is mounted, a plurality of film lines (264) on the film, and at least one dummy pattern (DP) on the film between an adjacent pair of films in the plurality of film lines.