Bump Electrode Convex Structure for Display Driver Contact Stability
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Solution Overview
Problem
Contact errors between a driver and a substrate in display devices can occur due to dimples on the bump electrode, leading to instability in signal transmission.
Innovation Solution
A display device design featuring a driver with a convex structure and bump electrode, where the bump electrode includes a column covering the convex structure and a protruding convex portion, which contacts a contact auxiliary electrode, stabilizing the connection between the driver and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bump electrode is used for mounting the driver, then the mounting process is simple, but contact errors occur due to dimple formation leading to unstable connection
Solution Approach 1:
The bump electrode is segmented into three distinct parts: a column body, a convex structure at the lower end, and a convex portion at the upper end. This segmentation allows each part to serve a specific function - the column provides structural support, the convex structure prevents dimple formation, and the convex portion ensures stable contact with the pad electrode, thereby resolving the contradiction between reliability and complexity.
Solution Approach 2:
The convex structure is formed at the lower end of the bump electrode before mounting, protruding in advance toward the pad electrode. This preliminary action ensures that when the driver is mounted, the convex structure makes contact first, preventing dimple formation and ensuring stable electrical connection, thus improving reliability without significantly increasing complexity.
2Manufacturing precision
If the bump electrode is made with a simple cylindrical shape, then manufacturing is easier, but dimples form causing contact errors
Solution Approach 1:
The bump electrode employs local quality by creating specific geometric features at particular locations: a convex structure at the lower end and a convex portion at the upper end. These localized geometric modifications address the specific problem of dimple formation and contact instability without requiring complex manufacturing processes throughout the entire electrode, thus improving manufacturing precision while maintaining ease of manufacture.
3Reliability
If a convex structure is added to the bump electrode, then contact stability improves, but the device structure becomes more complex
Solution Approach 1:
Instead of trying to eliminate the convex structure to reduce complexity, the invention inverts the approach by intentionally designing the bump electrode with convex features (convex structure and convex portion) that leverage the protruding geometry to prevent dimple formation and ensure stable contact. This inversion transforms the potential complexity into a solution that improves reliability.
Data Source
AI summary
A display device includes: a flexible substrate having a display area for displaying an image and a peripheral area outside the display area; a first pad electrode in the peripheral area of the flexible substrate; and a driver connected to the first pad electrode. The driver includes: a circuit board including a driving circuit; a second pad electrode on one side of the circuit board and facing the first pad electrode; a convex structure on one side of the second pad electrode and having an oval cross-section; and a bump electrode on one side of the convex structure and connected to the first pad electrode. The bump electrode includes a column covering the convex structure and a convex portion extending from one side of the column and protruding to the first pad electrode.