TFT Array Substrate Stepped Insulating Film Short Circuit Prevention
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Solution Overview
Problem
Flexible display devices face issues with short circuits between wirings due to conductive film remnants in stepped portions, which existing technologies fail to address effectively.
Innovation Solution
A TFT array substrate with a flexible substrate and a first inorganic insulating film having a stepped portion with convex portions on adjacent wiring surfaces, where the second inorganic insulating film is used to prevent electrical connection between adjacent wirings by removing conductive film residues in the stepped region during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the insulating layer is partially removed to form a step for making the flexible display easy to bend, then the flexibility is improved, but the conductive film is likely to remain between adjacent wirings causing short circuit
Solution Approach 1:
The insulating layer is segmented into different height levels, creating stepped portions at specific locations between adjacent wirings. This segmentation allows the insulating layer to provide both mechanical flexibility (through the stepped structure that reduces bending stress) and electrical isolation (by maintaining insulation at critical locations where conductive film remnants might cause short circuits).
Solution Approach 2:
The insulating layer is selectively removed only in specific stepped portions located between adjacent wirings, rather than uniformly across the entire structure. This local modification maintains the necessary flexibility in critical areas while preserving electrical insulation where short circuits are most likely to occur, thus addressing both flexibility and reliability requirements locally rather than globally.
2Reliability
If the insulating layer is completely removed to eliminate conductive film remnants, then short circuit prevention is improved, but the flexibility and structural integrity deteriorate
Solution Approach 1:
Instead of removing the entire insulating layer, only the necessary stepped portions are extracted or removed. This selective extraction eliminates conductive film remnants in critical areas where short circuits are most likely, while leaving the majority of the insulating layer intact to maintain the overall flexibility and structural integrity of the flexible display device.
3Reliability
If the conductive film is thoroughly cleaned from stepped portions, then short circuit prevention is improved, but the manufacturing complexity increases
Solution Approach 1:
The insulating layer is pre-structured with stepped portions during the manufacturing process, before the conductive film is deposited. This preliminary action creates a geometric configuration that naturally prevents conductive film remnants from forming continuous conductive paths, thereby simplifying subsequent cleaning processes and reducing manufacturing complexity while ensuring reliable short circuit prevention.
Data Source
AI summary
In the second area, the lower base surface of the wirings is in contact with the first inorganic insulating film including a stepped portion including upper surfaces having mutually different heights and being adjacent to each other in the second direction, and a stepped surface rising from the upper surfaces except the uppermost surface. The first inorganic insulating film constitutes at least the upper surfaces except the lowest surface, and the stepped surface. The adjacent wirings include a pair of convex portions protruding toward a direction facing each other. One and the other of the pair of convex portions are separated to face each other at a position where the stepped portion does not exist in the second area in the first inorganic insulating film.