COP Bonding Insulation Structure to Prevent Terminal Short Circuits
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Solution Overview
Problem
During chip on polyimide (COP) bonding processes, conductive particles in anisotropic conductive film (ACF) adhesives are pressed into spaces between bump terminals, causing electrical conduction between adjacent terminals and resulting in short circuits.
Innovation Solution
A display device design featuring a first insulating layer with a thickness less than or equal to one tenth of the diameter of electrically conductive particles, and a second insulating layer on the sides of bonding terminals, which prevents conductive particles from aggregating and causing short circuits by providing insulation and restricting particle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACF adhesive is used for bonding ICs to display panels, then bonding strength and electrical conduction are improved, but conductive particles are pressed into spaces between bump terminals causing short circuits
Solution Approach 1:
The patent divides the bonding structure into distinct functional zones by introducing insulating layers between adjacent bonding terminals. The first insulating layer is positioned between bump terminals on the IC, while the second insulating layer is positioned between corresponding terminals on the display panel, creating segmented isolation zones that prevent conductive particle migration while maintaining bonding functionality.
Solution Approach 2:
The patent introduces insulating layers as intermediary structures between the conductive bump terminals and the ACF adhesive. These insulating layers act as mediators that allow the ACF to provide bonding strength and electrical conduction through the bump terminals while blocking the harmful migration of conductive particles into the spaces between terminals, thus eliminating short circuit risks.
2Reliability
If insulating layers are added to prevent short circuits, then short circuit risk is reduced, but device structure and manufacturing complexity increase
Solution Approach 1:
The patent merges the insulating layer formation process with the existing ACF bonding process. The first and second insulating layers are integrated into the bonding structure such that they are formed and positioned simultaneously with the ACF adhesive application, rather than as separate additional steps. This merging approach maintains electrical insulation reliability while avoiding significant increases in manufacturing complexity.
Solution Approach 2:
The patent employs thin film insulating layers that are flexible and conformal in nature, allowing them to adapt to the bonding surface topology without requiring complex rigid structures. These thin film insulating layers provide effective electrical isolation while maintaining process simplicity and avoiding significant increases in device structural complexity.
3Reliability
If thicker insulating layers are used to prevent particle penetration, then insulation effectiveness is improved, but vertical bonding area is reduced
Solution Approach 1:
The patent applies local quality by positioning insulating layers specifically in the critical regions between adjacent bonding terminals where conductive particle migration is most likely to occur. The insulating layers are not uniformly thick across the entire bonding area but are strategically placed and dimensioned only where needed for insulation, thus maintaining insulation effectiveness while preserving maximum vertical bonding area for electrical conduction.
Solution Approach 2:
The patent employs partial action by providing insulating protection only in the specific locations where it is necessary to prevent short circuits, rather than covering the entire bonding area uniformly. The first and second insulating layers are positioned selectively between terminals with dimensions optimized for local insulation needs, avoiding excessive material that would reduce the vertical bonding area available for electrical conduction.
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 short circuits while maintaining vertical electrical conduction, reducing processing difficulties, expanding the selection range for conductive particle diameters, and lowering purchase costs without altering the vertical bonding area.
Implementation Method 1
Under a combined effect of temperature, pressure, and time
Implementation Method 2
Under a combined effect of temperature, pressure, and time
Implementation Method 3
the first insulating layer has a thickness less than or equal to one tenth of a diameter of each of the electrically conductive particles
Implementation Method 4
electrical conduction between ICs and display panels in a vertical direction and insulation in a horizontal direction are realized by conductive particles in the ACF adhesive
Data Source
AI summary
A display device includes a display panel and an integrated circuit chip configured with a plurality of first bonding terminals spaced apart from each other. The display panel is provided with a plurality of second bonding terminals, and a first insulating layer is disposed between the first bonding terminals and the second bonding terminals. A plurality of electrically conductive particles are provided on the second bonding terminals and penetrate the first insulating layer so that the electrically conductive particles are in contact with the first bonding terminals.