Papers by Keyword: Defects Inspection

Abstract: SmartSiC^TM technology enables the supply of cost-effective and high-quality substrates to support the manufacturing of Silicon Carbide (SiC) Power Devices and the transition to High Volume Manufacturing (HVM) [1]. As detailed in [2] SmartSiC^TM is prepared using a poly-crystalline handle wafer, it combines the benefit from both an optimized high quality epi-ready 4H-SiC layer and an ultra high conductivity handle material. Smart Cut^TM technology can be extended to SiC 200mm substrates and first SmartSiC^TM 200mm sample has been prepared [2].SmartSiC^TM substrates crystal quality is inherited by donor wafers [1, 2] and do not require a systematic control, enabling a new defects monitoring strategy, focusing on surface defects.This paper describes how a commercially available DUV inspection system was utilized for high sensitivity, high-throughput inspections of 150 and 200 mm 4H-SiC and SmartSiC^TM substrates, for the HVM environment. The KLA Surfscan^® SP A2 unpatterned wafer inspection system offers the opportunity to complement other inspection technologies to optimize SiC substrate defect control, with low threshold detection, below 150 nm.

Abstract: In this paper, the real-time defects inspection was implemented via use of paralleled structure and high-speed operation of FPGA. The hardware circuit based on FPGA was established. According to signal characteristics of polymeric film defects, the preprocessing scheme of defect images based on FPGA was designed. The defect data were packed according to the defined format. Data processed were transferred to PC through USB2.0 real-timely to reconstruct defect microscopic images. The quantity of transferred data was decreased tremendously by this method. The inspecting speed was greatly improved.

Abstract: In an online defects inspection system for cord fabric based on machine vision, Image segmentation for cord fabric defects has been the heat and difficult problem. An adaptive segmentation algorithm using threshold surface is presented in this paper. This method inspects defects through detecting the change of image gray levels caused by the difference in optic character between glass and defects. The experiment results indicate that the proposed method has low computation cost, fast speed and good segmentation performance. It is in accord with the requirements of online inspection system such as reliability, real-time, and veracity

Abstract: To solve the crossing-linkable polyethylene (XLPE) insulation compound purity evaluation problem, a high speed scanning measurement system was designed according to FPGA. With the updated information technology and advanced electronic devices, it is possible to develop a new inspecting technology for sorting, checking and evaluating material quality, by which defects microscopic images can be real-time recorded, processed and displayed. The result shows that this system can measure the size of impurity particles of XLPE cable materials correctly, it also can find out the accurate location and numbers of impurity particles. The resolving power of this method can reach 20 m and the error is less than 10%.The possibility that the impurity particles can be checked out is up to 100%.

Abstract: In hot slab continuous casting (CC) process, the Machine Vision (MV) inspection method for slab surface defects has been becoming a research focus with the development of charge-coupled device (CCD) camera imaging technologies. To acquire a informative and reliable defects image is a prerequisite that means a maximum defects detection rate and minimum false recognition in the next image processing stage. In this paper, based on the CCD imaging principle and definition evaluation algorithm, the slab surface radiation feature at high temperature and CCD optical imaging properties had been analyzed under the focal plane, meanwhile, the CCD image definition of optical integral time controlling method had also been studied, which the defect image variance (IV) function, image average gradient (IAG) and information entropy (IIE) were calculated and analyzed. In the end, the image definition controlling algorithm for hot slab surface ROI imaging that adopted IIE evaluation algorithm, based on CCD integral time imaging controlling principle, had been proposed. This method also can support practical value for other machine vision engineering.

Abstract: Surface quality of bearing ball is one of important factors to improve service performance. It is difficult to detect bearing ball surface defects with high precision and low cost by conventional methods. In this paper one new classification method based on optical fiber sensing technology was put forward from the longitudinal section angle. Inspection mechanism of Y-type and coaxial fiber sensor were analyzed, the mathematical models of the two fiber sensors were established and numerical simulations were realized by Matlab software. Influence of optical fiber parameters on light intensity modulation characteristic regulation was studied. Light intensity modulation characteristic experiments were done with specimens of different reflectivity and processing methods. The results show optical fiber sensing technique is an effective method to separate different surface of steel ball with extracting of two parameters displacement and surface reflectivity.

Abstract: Magnetic flux leakage (MFL) is a non-destructive testing method used to inspect ferrous materials. However, apparatus parameters could affect the MFL inspection tool’s ability to characterize anomalies. In this paper, MFL signals obtained during the inspection of pipes have been simulated using three-dimensional finite element analysis and the effects of magnet assembly on MFL signals are investigated. According to numerical simulations, an increase in the leakage flux amplitude is observed with an increase in the permanent magnet size and the inflexion point may indicate the presence of magnetizing pipe wall to near saturation. It clearly illustrates degradation in the MFL with increasing backing iron length. The relationship between MFL apparatus parameters and MFL signals could be utilized in the MFL technique to characterize the defect.

Abstract: Recent years, automated optical inspection (AOI) is developed very fast along with the rapid development of the emerging industries of semiconductor, LCD, PCB, optical communication and precision assembly, and also widely used in the industries of robot, automobile, steel, textile, printing, medicine, etc. In this paper, we will take a review of the AOI techniques, which are used for defect inspection on a large surface, such as inspecting the quality of TFT-LCD glass substrate and filter. The AOI system architecture having high inspection speed is illustrated. Some key techniques of light illumination, distributed image processing and convey mechanism, are explained.

Abstract: A mura defect detection algorithm for thin-film transistor liquid crystal display (TFTLCD) is developed for automatic detection of mura defects using Discrete Cosine Transform (DCT) principle for background image reconstruction. Detecting blob-mura defects in a LCD panel can be difficult due to non-uniform brightness background and slightly different brightness levels between the defect region and the background. To resolve this issue, a DCT-based background reconstruction algorithm was developed to establish the background image. The background of the inspected images can be first extracted and reconstructed by using the DCT principle and an image filtering strategy. Mura defects can then be detected by the developed segmented strategy. Actual performance of the developed method was evaluated on industrial LCD panels containing natural mura defects.