Array Substrate Step Geometry to Prevent Functional Layer Cracking
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Solution Overview
Problem
In display technology, the functional layers on array substrates are prone to breaking at level-different regions, leading to potential short circuits and yield issues, particularly in thin display products, as existing solutions like increasing layer thickness are not suitable for both thinness and high-resolution requirements.
Innovation Solution
The array substrate incorporates a first functional layer with a target gradient angle and a second functional layer of predetermined thickness, where the second functional layer covers the level-different region without breaking, meeting functional requirements while maintaining a balance between thickness and gradient angle to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the functional layer is increased to prevent breaking at the step, then the reliability of the functional layer is improved, but the thinness of the display product deteriorates
Solution Approach 1:
The patent applies local quality by creating a gradient angle structure specifically at the level-different region where the functional layer crosses the step. Instead of uniformly increasing the thickness of the entire functional layer, the gradient angle is localized to the critical area where breaking risk exists. This allows the functional layer to have sufficient thickness at the step region to prevent breaking while maintaining thinness in other regions, thus resolving the contradiction between reliability and overall thickness.
Solution Approach 2:
The patent changes the geometric parameter of the functional layer from a uniform horizontal top surface to a gradient angled surface at the level-different region. By controlling the gradient angle within a specific range (15°-45°), the patent optimizes the stress distribution and prevents breaking without requiring excessive thickness. This parameter change allows the functional layer to maintain both integrity and thinness simultaneously.
2Length of stationary object
If the gradient angle of the first functional layer is increased to reduce the thickness of the second functional layer, then the thinness of the display product is improved, but the risk of the second functional layer breaking increases
Solution Approach 1:
The patent establishes a quantitative relationship between the gradient angle of the first functional layer and the thickness of the second functional layer through the formula: Tanα-1≤N(x-y)/y≤Tanα+1. This parameter change approach allows precise control of the gradient angle to ensure that the second functional layer maintains sufficient thickness to prevent breaking while achieving the desired thinness. The formula provides a mathematical basis for optimizing both parameters simultaneously.
Solution Approach 2:
The patent incorporates feedback by using the fracture toughness parameter (KIC) of the second functional layer and the thickness relationship in the design formula. The gradient angle is determined based on the actual material properties and thickness requirements, creating a feedback loop where material characteristics inform the geometric design. This ensures that the gradient angle is appropriately adjusted based on the specific functional layer properties to prevent breaking.
3Reliability
If the thickness of the second functional layer is increased to prevent breaking, then the reliability is improved, but the material cost increases
Solution Approach 1:
The patent applies local quality by concentrating the necessary thickness only where needed - at the level-different region with the gradient angle structure. The second functional layer maintains sufficient thickness locally at the step region to prevent breaking, while being thinner in other areas. This localized thickness distribution reduces overall material consumption while maintaining reliability, resolving the contradiction between integrity and material cost.
Data Source
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AI summary
The present disclosure provides an array substrate, a manufacturing method thereof, and a display device. The array substrate includes a base substrate, and a first functional layer and a second functional layer laminated one on another on the base substrate. The first functional layer forms a level-different region on the base substrate, and the second functional layer covers the level-different region. A portion of the first functional layer at the level-different region is provided with a target gradient angle, the target gradient angle is a maximum gradient angle when the second functional layer has a predetermined thickness, and the predetermined thickness is a thickness when a functional requirement of the second functional layer has been met and the second functional layer is not broken at the level-different region.