Pad Electrode Segmentation for Display Driver Connection Stability
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Solution Overview
Problem
In display devices, short circuits can occur between adjacent pads or the bump electrode and pads may not be properly coupled, leading to unstable electrical connections between the driver and substrate.
Innovation Solution
A display device design featuring a substrate with a pad portion including first, second, and third pad electrodes, where the third pad electrode has a greater width than the second and first, and an auxiliary layer with varying thicknesses between these electrodes, providing a stable connection by using an organic material and ensuring proper contact with the driver's bump electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard pad structure is used for electrical connection between driver and substrate, then the connection process is simple, but short circuits may occur between adjacent pads or bump electrodes may not be properly coupled
Solution Approach 1:
The pad structure is segmented into three distinct electrode layers (first, second, and third pad electrodes) with different widths and positions. This segmentation allows each electrode to serve specific functions: the first and second electrodes provide electrical connection paths, while the wider third electrode ensures stable coupling with the bump electrode, thereby preventing short circuits and improving connection reliability without excessive complexity
Solution Approach 2:
The auxiliary layer is designed with non-uniform thickness, being thicker at specific locations between the third pad electrode and the interlayer insulating layer. This local quality variation provides enhanced insulation and mechanical support precisely where needed to prevent short circuits, while maintaining overall structural simplicity
2Reliability
If the third pad electrode has greater width than the first and second pad electrodes, then the coupling with bump electrode is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The first, second, and third pad electrodes are formed in a predetermined sequential order during the manufacturing process. By establishing the electrode width hierarchy (third electrode wider than first and second) in advance during fabrication, the design ensures proper bump electrode coupling is achieved before final assembly, reducing the need for high-precision adjustments later in the manufacturing process
Data Source
AI summary
A display device includes: a substrate; a pad portion in a non-display area of the substrate and including a plurality of pads; a driver arranged at the pad portion to contact the pads; an interlayer insulating layer on the substrate; and an auxiliary layer in the non-display area, and each of the pads includes a first pad electrode, a second pad electrode, and a third pad electrode, which are sequentially arranged on the substrate, a width of the third pad electrode is greater than a width of the second pad electrode and a width of the first pad electrode, and a thickness of the auxiliary layer between the third pad electrode and the interlayer insulating layer is thicker than a thickness of the auxiliary layer between the third pad electrode and the second pad electrode.