Transparent Conductive Layer for COG Terminal Rigidity
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Solution Overview
Problem
The existing COG structure for active matrix display apparatuses faces challenges in achieving sufficient connection due to the softness of the planarization film, which affects the application of pressure onto the ACF, leading to inadequate connection in the terminal portion.
Innovation Solution
A transparent conductive layer formed on a connection portion using aluminum or aluminum alloy is used, providing rigidity and reducing contact resistance while preventing the formation of an oxide film, thus ensuring effective connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a planarization film is used to cover the connection portion in the COG terminal portion, then the surface is planarized and protected, but the connection rigidity is insufficient due to the softness of the planarization film
Solution Approach 1:
The patent employs a composite structure consisting of a planarization film layer and a transparent conductive film layer. The planarization film provides surface planarity and protection, while the transparent conductive film adds rigidity to the connection portion. This composite material approach allows the terminal portion to maintain both surface planarity and sufficient connection rigidity simultaneously.
2Reliability
If pressure is applied onto the ACF in the terminal portion, then connection is established, but the soft planarization film deforms and prevents effective pressure transmission
Solution Approach 1:
The transparent conductive film forms a rigid composite structure with the planarization film, creating a reinforced connection portion. This composite structure maintains structural integrity under pressure, enabling effective pressure transmission to the ACF while preventing deformation of the underlying planarization film.
Solution Approach 2:
The patent applies local reinforcement by forming the transparent conductive film specifically at the connection portion where rigidity is needed, while the rest of the planarization film maintains its soft, planarizing properties. This localized quality change allows pressure to be effectively transmitted at the terminal portion without compromising the overall surface planarity.
3Strength
If the connection portion is exposed without coverage, then pressure application is effective, but the conductor is susceptible to oxidation and contact resistance increases
Solution Approach 1:
The patent uses a composite structure where the transparent conductive film serves dual functions: it provides mechanical rigidity for effective pressure application and simultaneously acts as a protective barrier preventing oxide film formation on the underlying aluminum or aluminum alloy conductor, thereby maintaining low contact resistance.
Solution Approach 2:
The transparent conductive film acts as an intermediary layer between the aluminum connection portion and the external environment. It protects the aluminum from oxidation while allowing electrical conduction and mechanical pressure transmission, resolving the contradiction between exposure and protection.
Data Source
AI summary
A portion of a protective layer located above a connection portion is removed to expose the connection portion which is formed of the same material as used for a data line DL in this removed portion. Then, a transparent conductive layer made of ITO is further formed on these films. The transparent conductive layer and a bump are then connected via an AFC.