Stacked Pad Electrode Layout for Bezel-Less Display Interconnects
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Solution Overview
Problem
Current display device fabrication methods face challenges in achieving high efficiency and reliability, particularly in the integration of light emitting elements and electrodes, which affects the overall performance and design of display devices.
Innovation Solution
The proposed solution involves a display device structure with a substrate having a display area and a non-display area, featuring a light emitting element on one surface, pad electrodes with specific material combinations, and side connection lines that connect these electrodes, allowing for efficient electrical connections and a bezel-less design. The method includes forming pixel circuit layers, electrodes, and light emitting elements with precise etching processes to enhance fabrication efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fabrication methods are used with traditional electrode structures, then the fabrication process is simpler, but the non-display area increases and mounting density decreases
Solution Approach 1:
The pad electrode structure transitions from a conventional planar configuration to a three-dimensional stacked configuration with first and second pad electrodes arranged vertically. This dimensional change allows electrical connections to be established through the thickness direction, thereby reducing the lateral footprint and increasing the display area without compromising connectivity functionality.
Solution Approach 2:
The pad electrode is divided into multiple discrete components (first pad electrode and second pad electrode) that are stacked and independently controlled through separate etching processes. This segmentation enables precise positioning and reduces the overall area required for electrical connections, thereby increasing mounting density.
2Reliability
If precise etching processes are implemented for stacked electrodes, then fabrication reliability improves, but process complexity increases
Solution Approach 1:
The fabrication process employs preliminary patterning steps where masks are strategically positioned to define the stacked pad electrode structure before etching. The first mask pattern defines the first pad electrode, and the second mask pattern defines the second pad electrode, ensuring precise alignment and reducing the need for complex real-time adjustments during etching.
Solution Approach 2:
The etching process utilizes parameter changes by adjusting etching conditions (such as etchant concentration, temperature, or plasma power) between the first and second etching steps. This allows selective removal of materials to expose specific electrodes while maintaining the integrity of other structures, thereby simplifying the overall process despite the stacked configuration.
3Area of stationary object
If the pad electrode area is reduced to increase display area, then the bezel-less design is achieved, but electrical connection reliability may deteriorate
Solution Approach 1:
The electrical connection function is migrated from the lateral plane to the vertical dimension through the stacked pad electrode configuration. The first and second pad electrodes are arranged in the thickness direction, allowing sufficient connection area to be achieved vertically rather than laterally, thus reducing the non-display area while maintaining connection reliability.
Solution Approach 2:
The stacked pad electrode structure effectively creates a composite electrode system where the first pad electrode (with opaque conductive material) and second pad electrode (with transparent conductive material) work together. This composite structure provides both electrical connectivity and optical functionality, ensuring reliable electrical connection while minimizing the footprint.
Data Source
AI summary
A display device may include: a substrate having a display area and a non-display area, and including a first surface and a second surface facing away from each other in a thickness direction of the substrate, and a side surface connecting the first and second surfaces; a light emitting element on the first surface of the substrate in the display area; a pad electrode on the first surface of the substrate in the non-display area; an intermediate electrode on the second surface of the substrate in the display area; and a side connection line on the side surface, and electrically connected to each of the pad electrode and the intermediate electrode. The pad electrode may include a first pad electrode and a second pad electrode. Opposite side surfaces of the second pad electrode may have the same inclination angles as opposite side surfaces of the first pad electrode.