TFT Array Substrate Repairing Defective Storage Capacitors
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Solution Overview
Problem
Defective storage capacitors in TFT array substrates due to process defects lead to abnormal pixel display and reduced manufacturing yields in LCD panels, particularly affecting wide-view-angle LCDs like MVA, IPS, and FFS displays.
Innovation Solution
A TFT array substrate design with a passivation layer, conductive lines, and top electrodes that include sub-electrodes and connection parts, along with a repairing method using laser removal and welding to isolate defective pixels and restore functional capacitors, thereby preventing charge leakage and shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TFT array formation process is used, then manufacturing process is simple, but storage capacitors are prone to defects causing pixel failures
Solution Approach 1:
The top electrode is divided into multiple sub-electrodes (first top sub-electrode, second top sub-electrode) that are spatially separated. This segmentation allows independent formation and testing of storage capacitors, isolating defects to specific regions and enabling selective repair without affecting the entire pixel array.
Solution Approach 2:
A conductive line is introduced as an intermediary element to connect sub-electrodes to pixel electrodes. This conductive line serves as a testable interface that allows detection of storage capacitor defects and facilitates repair operations by providing access points for laser removal and welding processes.
2Productivity
If laser removal and welding is used to repair defective pixels, then manufacturing yield is improved, but repair process complexity increases
Solution Approach 1:
The top electrode is pre-divided into sub-electrodes with conductive lines connecting them to pixel electrodes during the initial formation process. This preliminary segmentation creates accessible test points and isolation structures that simplify subsequent repair operations, allowing defective areas to be identified and treated without complex reconfiguration.
Solution Approach 2:
Defective portions of conductive lines or sub-electrodes are selectively removed using laser removal to isolate defects. By extracting only the problematic segments rather than entire components, the repair process maintains simplicity while effectively preventing defect propagation to adjacent pixels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively repairs defective pixels, ensuring normal functionality and enhancing manufacturing yields by isolating defects and reconfiguring capacitors, thus improving display quality and addressing the issue of abnormal pixel display.
Implementation Method 1
a portion of the top electrode and the conductive line are removed by use of a laser beam so that the pixel electrode and the data line are electrically isolated from each other
Implementation Method 2
the second top sub-electrode and the common line corresponding thereto are welded by use of a laser beam so that the second top sub-electrode, the dielectric layer, and the common line constitute a functional storage capacitor
Data Source
AI summary
A thin film transistor array substrate and a repairing method thereof are provided. The thin film transistor array substrate comprises a substrate, plural scan lines, plural data lines, plural common lines, and plural pixels. The scan lines and the data lines are disposed over the substrate and define plural pixel areas. Each pixel is disposed in one of the pixel areas corresponding thereto. Each pixel comprises a thin film transistor, a pixel electrode, a top electrode, and a conductive line. In each pixel, the thin film transistor is coupled to the corresponding scan line and the corresponding data line, and the pixel electrode is disposed over the corresponding common line. Furthermore, the top electrode is disposed between the corresponding pixel electrode and common line, and the conductive line is disposed out of the corresponding common line and coupled between the corresponding top electrode and pixel electrode.