Display Pad Concave Structure for Driver IC Alignment
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Solution Overview
Problem
The existing methods for connecting driver ICs to OLED display panels, such as the tap bonding process, often result in poor electrical connections due to the mobility of conductive balls in anisotropic conductive films and deformation of flexible films, leading to disconnections and alignment issues.
Innovation Solution
The use of an anisotropic conductive film with conductive balls held in concave portions of the pad structure, combined with insulating layers and contact holes, ensures secure alignment and connection of bumps and pads, preventing disconnections and misalignment during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tap bonding process is performed with mobile conductive balls in anisotropic conductive film, then electrical connection between pads and bumps can be established, but the conductive balls may move to the outside causing poor electrical connection or disconnection
Solution Approach 1:
The patent applies preliminary action by forming convex portions on the pad structure before the bonding process. These convex portions are designed to hold the conductive balls in predetermined positions, preventing them from moving outside during the bonding process. This pre-positioning mechanism ensures that conductive balls remain between the pads and bumps throughout the process, maintaining reliable electrical connections.
2Reliability
If heat is generated during the tap bonding process, then electrical connection can be established, but the flexible film may deform causing bump position shift and poor electrical connection
Solution Approach 1:
The patent applies preliminary action by forming convex portions on the pad structure before the bonding process. These convex portions are designed to hold the conductive balls in predetermined positions, preventing them from moving outside during the bonding process. This pre-positioning mechanism ensures that conductive balls remain between the pads and bumps throughout the process, maintaining reliable electrical connections.
3Reliability
If the anisotropic conductive film is used for connecting driver IC to display panel, then electrical connection can be achieved, but alignment between pads and bumps is difficult due to lack of position control
Solution Approach 1:
The patent applies preliminary action by forming convex portions on the pad structure before the bonding process. These convex portions are designed to hold the conductive balls in predetermined positions, preventing them from moving outside during the bonding process. This pre-positioning mechanism ensures that conductive balls remain between the pads and bumps throughout the process, maintaining reliable electrical connections.
Solution Approach 2:
The patent applies the intermediary principle by introducing convex portions as a mediating structure between the pads and bumps. These convex portions serve as position control elements that guide and hold the conductive balls, facilitating precise alignment between the driver IC bumps and the display panel pads during the bonding process.
Data Source
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Figure 4(a)~4(b)
AI summary
A display device can include a substrate including a display area, on which an input image is displayed, and a pad part including a convex portion and a concave portion that are alternately positioned outside the display area and have a height difference between them, and a circuit element attached to the pad part and including a bump inserted into the concave portion of the pad part. The pad part can further include a lower pad electrode electrically connected to a signal line extended from the display area, a first insulating layer disposed on the lower pad electrode in the convex portion, and an upper pad electrode disposed on the first insulating layer, connected to the lower pad electrode through a first contact hole penetrating the first insulating layer and extending into at least a portion of the concave portion.