X-ray Flat Panel Detector TFT Array Substrate Inspection
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Solution Overview
Problem
The existing methods for digitizing X-ray images using silver halide film require re-scanning, which is time-consuming, and indirect conversion X-ray flat panel detectors face challenges in inspection accuracy due to leakage current from protection diodes, potentially passing defective arrays to subsequent processes.
Innovation Solution
The method involves manufacturing an X-ray flat panel detector TFT array substrate with protection diodes between interconnect rings and scanning/signal lines, and applying a reference bias voltage to improve inspection accuracy by minimizing leakage current through the diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection diodes are added to prevent static electricity damage, then reliability is improved, but leakage current increases reducing inspection accuracy
Solution Approach 1:
A preliminary inspection is performed before the protection diodes are formed. The inspection unit checks for defects in the TFT array substrate before the protection diodes are created in the electrostatic protection film formation step. This allows defect detection to occur when the protection diodes are not yet present and cannot interfere with the measurement, thus maintaining both reliability (by adding protection diodes later) and inspection accuracy (by inspecting before they are added).
Solution Approach 2:
The manufacturing process is segmented into distinct stages: first forming the TFT array substrate, then performing inspection, and finally forming the protection diodes in the electrostatic protection film. This segmentation separates the inspection process from the presence of protection diodes, eliminating the interference problem while still providing electrostatic protection in the final product.
2Reliability
If inspection is performed after protection diodes are formed, then reliability is improved, but defective arrays may be missed due to leakage current
Solution Approach 1:
The inspection is performed as a preliminary action before the protection diodes are formed. The flow chart shows that after forming the TFT array substrate, the inspection unit inspects for defects before the electrostatic protection film with protection diodes is formed. This preliminary timing ensures that no leakage current from protection diodes can mask defective pixels during inspection.
3Productivity
If larger screen detectors are manufactured, then productivity is improved, but manufacturing complexity increases
Solution Approach 1:
By performing inspection before forming the protection diodes, the method enables reliable quality control in large-area detectors without increasing manufacturing complexity. The preliminary inspection approach works equally well for both small and large screens, allowing the production of larger detectors with maintained quality assurance.
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
This approach enhances the inspection accuracy of the TFT array substrate, reducing the likelihood of defective arrays progressing to the next process and enabling the production of thinner, larger-screen X-ray detectors.
Implementation Method 1
protection diodes are formed in the TFT array to prevent the degradation and breakdown due to static electricity or static electric charge generated in the array construction process
Implementation Method 2
an inspection process of inspecting the X-ray flat panel detector TFT array substrate by applying a reference bias voltage to the external voltage application pad, providing a signal to the scanning line connection pad to switch the thin film transistor ON, and reading, from the signal line connection pad, an electrical signal flowing through the signal line
Data Source
AI summary
A common interconnect ring is provided at a periphery of a portion used to form a TFT array of an X-ray flat panel detector, and an X-ray flat panel detector TFT array substrate connected to signal lines and scanning lines via pairs of two protection diodes connected in parallel and having mutually-reverse polarities is manufactured. When inspecting the X-ray flat panel detector TFT array substrate, the same reference bias voltage as the amplifier of a detection circuit is applied from an external voltage application pad provided at the vicinity of a connection unit for the common interconnect ring and the protection diodes on the same side of the signal lines, a signal is provided to a scanning line connection pad to switch the thin film transistor ON, and an electrical signal flowing through the signal line is read from a signal line connection pad.