TFT Substrate Terminal Corrosion Prevention via Metal Film Extraction
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Solution Overview
Problem
TFT array substrates face reliability issues due to local corrosion at gate line terminals and short ring lines exposed to corrosive atmospheres, particularly when using Al-based metal films, which affects the integrity and lifespan of liquid crystal display devices.
Innovation Solution
A TFT substrate design featuring a transparent conductive film pattern with a metal film removed from the terminal area and covered by an insulating film, preventing exposure and corrosion, while maintaining connectivity through a terminal configuration that extends from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal film is used in the gate line terminal to reduce resistance, then electrical conductivity is improved, but local corrosion occurs in corrosive atmospheres
Solution Approach 1:
The metal film is extracted (removed) from the gate line terminal region while being retained in the gate line formation region. This selective removal eliminates the corrosion-prone metal film from the terminal area that is exposed to corrosive atmospheres, while preserving the low-resistance benefits in the conductive path.
Solution Approach 2:
The gate line structure has different compositions in different regions: the gate line formation region has a two-layer structure (transparent conductive film + metal film) for low resistance, while the gate line terminal region has only the transparent conductive film to prevent corrosion. This local differentiation of material composition resolves the contradiction between conductivity and corrosion resistance.
2Ease of manufacture
If the gate line terminal has the same configuration as the gate line with stacked films, then manufacturing is simplified, but the uppermost metal film is exposed causing local corrosion
Solution Approach 1:
The metal film is taken out (removed) from the gate line terminal region during the manufacturing process. This can be achieved by adjusting the etching conditions or using a resist mask that prevents metal film deposition or removes it selectively from the terminal area, thereby preventing corrosion without significantly complicating the manufacturing process.
3Reliability
If a short ring line is formed to prevent element abnormalities, then reliability during manufacturing is improved, but the exposed metal film on the cut surface causes local corrosion
Solution Approach 1:
The metal film is removed from the short ring line in the same manner as the gate line terminal, eliminating the source of corrosion on the cut surface while preserving the short ring line's function of preventing element abnormalities during manufacturing.
Data Source
AI summary
The TFT substrate having a transparent conductive film pattern configuring a terminal that can be connected from outside and a first line extending from the terminal; a metal film that is removed from over the terminal and formed on the transparent conductive film pattern on the inside thereof; and an insulating film covering the metal film.