LCD Pad Crack Prevention via Continuous Color Filter Substrate
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Solution Overview
Problem
LCD devices suffer from cracks in the pad part of the TFT substrate due to external forces, primarily caused by the step height and reduced stiffness resulting from the separation of the color filter substrate and the upper polarizer, leading to continuous defects during drop tests.
Innovation Solution
Extending the color filter substrate and upper polarization film to cover the pad area and both side surfaces of the driver IC, creating a continuous layer that connects the display and non-display areas, thereby preventing cracks by distributing stress evenly and enhancing stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the driver IC is disposed in only a partial area of the TFT substrate, then the manufacturing cost and complexity are reduced, but a step height occurs between the color filter substrate and upper polarizer in the area where the driver IC is not disposed, leading to reduced stiffness and crack occurrence
Solution Approach 1:
The color filter substrate and upper polarizer are merged into a single integrated substrate structure that extends continuously across both display and non-display areas. This eliminates the step height between separate components and distributes mechanical stress uniformly, preventing crack formation in the pad area while maintaining the simplified driver IC placement configuration.
2Reliability
If a gap filling tape is disposed in the area where the driver IC is not disposed to prevent cracks, then crack prevention is attempted, but the coupled portions of the panel have gaps between them, causing troublesome reduction in stiffness and continuous crack occurrence
Solution Approach 1:
The color filter substrate and upper polarizer are combined into one continuous substrate without gaps or filling tapes. This integrated structure eliminates the stiffness reduction caused by gap filling materials while providing reliable crack prevention through uniform stress distribution across the entire panel surface.
3Ease of manufacture
If the color filter substrate and upper polarizer are provided as separate layers, then manufacturing flexibility is improved, but a step height occurs causing stress concentration and crack formation in the pad part during drop tests
Solution Approach 1:
The color filter substrate and upper polarizer are merged into a single integrated substrate that extends continuously across the entire panel including non-display areas. This eliminates step heights and stress concentration points that cause cracks during drop tests, while the integrated structure can still be manufactured using standard LCD manufacturing processes.
Data Source
AI summary
Disclosed is a liquid crystal display (LCD) device for preventing a crack from occurring in a pad part of a thin film transistor (TFT) substrate. The LCD device includes a liquid crystal display panel including a TFT substrate and a color filter substrate on an upper surface of the TFT substrate, a guide panel supporting the liquid crystal display panel, and a driver integrated circuit (IC) in a lower non-display area of the upper surface of the TFT substrate. The color filter substrate extends to the lower non-display area of the upper surface of the TFT substrate.