Laminography System Research Articles

Online learning for DBC segmentation of new IGBT samples based on computed laminography imaging

Insulated gate bipolar transistor (IGBT) is a power semiconductor module .Voids may arise in its solder process when a contaminant or gas is absorbed into the solder joint. They heavily influence the heat exchange efficiency of IGBT, so void inspection is very important. The segmentation of solder region is a crucial step for automated defect detection of IGBT based on x-ray computed laminography (CL) system. In recent years, deep learning has made remarkable process in semantic segmentation and has been used for the segmentation of solder joint between the direct bonded copper (DBC) substrate and baseplate, which has been proved to be accurate and efficient. However, deep learning architectures exhibit a critical drop of performance due to catastrophic forgetting when new IGBT samples encountered. Hence, this paper proposes to use online learning techniques to continuously improve the learned model by feeding new IGBT samples without losing previously learned knowledge.

Geometric calibration of a computed laminography system for high‐magnification nondestructive test imaging

Geometric calibration of a computed laminography system for high‐magnification nondestructive test imaging

Development of a truncation artifact reduction method in stationary inverse-geometry X-ray laminography for non-destructive testing

In an industrial field, non-destructive testing (NDT) is commonly used to inspect industrial products. Among NDT methods using radiation sources, X-ray laminography has several advantages, such as high depth resolution and low computational costs. Moreover, an X-ray laminography system with stationary source array and compact detector is able to reduce mechanical motion artifacts and improve inspection efficiency. However, this system, called stationary inverse-geometry X-ray laminography (s-IGXL), causes truncation artifacts in reconstructed images due to limited fields-of-view (FOVs). In this study, we proposed a projection data correction (PDC) method to reduce the truncation artifacts arisen in s-IGXL images, and the performance of the proposed method was evaluated with the different number of focal spots in terms of quantitative accuracy. Comparing with conventional techniques, the PDC method showed superior performance in reducing truncation artifacts and improved the quantitative accuracy of s-IGXL images for all the number of focal spots. In conclusion, the PDC method can improve the accuracy of s-IGXL images and allow precise NDT measurements.

一种迭代的锥束计算机层析成像系统几何全参数标定方法

一种迭代的锥束计算机层析成像系统几何全参数标定方法

Influences on 3D image quality in a high-resolution Xray laminography system

Recently, we demonstrated that projective X-ray microscopy is feasible with a two-dimensional spatial resolution down to 100 nm by using laboratory nanofocus X-ray sources and a geometric magnification of up to 1000x. Based on these previous results, we developed a high-resolution X-ray laminography system which uses an optimized thin-film X-ray transmission target together with a modified electron probe micro analyzer. Unlike conventional axial computed tomography (CT), 3D laminography imaging involves a linear translation of both detector and object with respect to a stationary point source.In this contribution we present a detailed characterization of the setup concerning especially the laminographic imaging mode. The quality of the volume reconstruction is assessed by simulating an ideal setup with an analytical model including features down to 200 nm which are resolved in the setup given a high enough SNR in the projections.We further address the issue of a drop in the detector resolution under oblique X-ray illumination which is a common problem to such systems. The finite penetration depth of the X-rays into the detector pixels causes an anisotropic blurring of the detector point spread function (PSF) under oblique irradiation. We tested the influence of this blurring by calculating the illumination-dependent modulation transfer function (MTF) of the detector. Our measurements are supported by numerical simulations of the detector MTF. Both simulations and measurements show a drop in spatial resolution (20% of the MTF) from 12.5 lp/mm (irradiation perpendicular to the detector screen) down to 5.2 lp/mm (irradiation 30° oblique to the screen).Furthermore, first examples of 3D imaging of test structures and material imaging are given.

Development of x-ray laminography under an x-ray microscopic condition

An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatial resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique.

Reverse geometry X-ray imaging

A Californian firm, Digiray Corporation, has made a breakthrough in X-ray imaging technology by inventing the 'Reverse Geometry X-ray'® imaging system, that improved signal-to-noise ratio by two orders of magnitude. This was accomplished by inverting the X-ray tube anode with the X-ray detector. The patented reverse-geometry X-ray system (RGX®) has been improved since, by coupling multiple detectors and developed further into a motionless laminography system (MLX®). The scanning X-ray source is located near the object and the divergent X-ray beam passing through this object is detected by an array of 64 detectors at some distance from it. All detectors acquire data simultaneously at different angles. Data are digitised and then stored and processed in a computer. The key interest of this process is its high resolution and contrast sensitivity. This is largely due to reduced scatter, as a result of using reverse geometry between the X-ray and source and detector. This system has been used for detection of cracks and corrosion in aircraft wings and fuselages and many other NDT applications. NASA used it to detect flaws in the Space Shuttle fuel tank insulating foam and its heat-resistant tiles.

A new approach to translational laminographic method for PCB inspection

X‐ray laminography, a tomographic technique that can examine individual planes of focus within a 3‐D structure, promises to be an excellent method of inspecting complicated circuit boards. The technique has accuracy appropriate for circuit board inspection, but the application has been limited by the requirements of synchronized motion of the source and detector, a sophisticated X‐ray device and a huge image acquiring system. A new translational laminography system is presented. The X‐ray source and detector described are stationary. Translation of the XY table is only the mechanical motion required to generate the laminographic image. Based on this system, a new image separation algorithm is also explained. This algorithm uses a recursive process with a simple mathematical function, which is derived analytically by the X‐ray projection geometry. To evaluate the proposed method, an X‐ray imaging system has been constructed. From the test sample experiments, it is confirmed that the proposed algorithm allows cleanly separated images with fewer artifacts than the one obtained by conventional laminography.

Computed laminography for materials testing

We have developed a computed laminography system for the inspection of large or flat objects using x rays. By this new laminographic method only a translation of the object is necessary. Both the x-ray source and the detector remain stationary. Object cross sections are reconstructed from digital projections taken during the object motions and for the reconstruction well-known algorithms are used. By use of a microfocus x-ray tube and a line detector, objects can be inspected with a slice resolution of about 50 μm independent of the object size.

4926542 Automated laminography system for inspection of electronics : Bruce D Baker, Robert L Corey, John Adams, Edward W Ross assigned to Four PI Systems Corporation

4926542 Automated laminography system for inspection of electronics : Bruce D Baker, Robert L Corey, John Adams, Edward W Ross assigned to Four PI Systems Corporation

Automated Finite-Element Mesh Generation for Surface Mount Technology Solder Joints

The ultimate goal of this work is an improved method to assess the significance of anomalies in surface mount technology (SMT) solder joints, by relating them to field performance and reliability. The fitness-for-purpose approach can be applied to SMT solder joints by relating specific characteristics or flaw indications in individual solder joints to their likelihood of failure, through finite element analysis. An effort is underway to automate the finite element modeling of actual solder joints by generating meshes from optical and X-ray inspection data in the form of thousands of surface points. Computer programs have been written to convert these surface points to finite element meshes. Two trial data sets have been meshed, one from an X-ray laminography system and one from a machine vision system.

Technology 1991: industrial electronics

Progress in industrial electronics during 1990 is reviewed. Fuzzy logic, intelligent control, and computer-integrated manufacturing (CIM) are improving manufacturing flexibility and reducing costs. At the same time, advanced computer numerical control (CNC) based on a reduced-instruction-set computer (RISC) chip is expected to sharpen precision in high-speed machining. There were notable advances toward an open system architecture for programmable controllers and machine vision systems. An X-ray laminography system for inspecting the solder joints on printed-circuit boards, particularly those of surface-mounted components, with 25 mu m resolution became available.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>