Array Substrate Via Hole Design for Corrosion Resistance
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Solution Overview
Problem
The corrosion of metal gate line leads in Liquid Crystal Display (LCD) array substrates due to water vapor penetration through via holes, which reduces the yield of the array substrate and display devices.
Innovation Solution
The use of transparent conductive contact electrodes formed in the same layer as either the pixel or common electrodes, with via holes in different insulating layers that do not overlap, to reduce water vapor penetration and prevent corrosion of the metal gate line leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via holes are used to connect metal wirings in different layers, then electrical connection between layers is achieved, but water vapor penetration causes corrosion of metal gate line leads
Solution Approach 1:
The invention transitions from a single-layer via hole structure to a multi-layer via hole structure. Specifically, it uses a first via hole extending from the first surface through the first insulating layer to expose the metal gate line lead, and a second via hole extending from the second surface through the second insulating layer to expose the transparent conductive contact electrode. This dimensional separation prevents water vapor from reaching the metal gate line lead through the via holes, thereby resolving the corrosion issue while maintaining electrical connectivity.
Solution Approach 2:
The invention introduces insulating layers as intermediary structures between the via holes and the metal gate line lead. The first insulating layer and second insulating layer act as barriers that prevent water vapor from penetrating to the metal gate line lead. Additionally, the transparent conductive contact electrode serves as an intermediary that provides electrical connection while being exposed at the second surface, away from the water vapor exposure risk at the first surface.
2Reliability
If transparent conductive contact electrode is added to prevent corrosion, then reliability is improved, but device complexity increases
Solution Approach 1:
The transparent conductive contact electrode performs multiple functions: it provides electrical connection between the metal gate line lead and external circuits, serves as a corrosion barrier by being positioned at the second surface away from water vapor exposure, and maintains optical transparency for display functionality. This multi-functionality achieves reliability improvement without proportionally increasing device complexity.
Solution Approach 2:
The invention segments the electrical connection path into two separate via holes positioned at opposite surfaces of the substrate. The first via hole at the first surface connects to the metal gate line lead, while the second via hole at the second surface connects to the transparent conductive contact electrode. This segmentation distributes the functional requirements across multiple components, achieving corrosion protection while maintaining electrical connectivity.
Data Source
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AI summary
An array substrate and a fabrication method thereof, a display device comprising the array substrate and a motherboard comprising the array substrate are provided. The array substrate comprises a pixel region (20) and a peripheral wiring region (30). The peripheral wiring region (30) comprises a transparent conductive contact electrode (301) disposed on a base substrate (10). The transparent conductive contact electrode (301) is electrically connected with a metal electrode line (2031, 2041) disposed below the transparent conductive contact electrode (301) through via holes (3021, 3022, 3023, 3024; 2051, 2052, 3061, 2053) disposed in different insulating layers, and the via holes (3021, 3022, 3023, 3024; 2051, 2052, 3061, 2053) disposed in different insulating layers do not overlap with each other in a projection direction.