X-ray Inspection System Research Articles

One Dimensional Linescan x-ray Detection of Pits in Fresh Cherries

The presence of pits in processed cherries is a concern for both processors and consumers, in many cases causing injury and potential lawsuits. While machines used for pitting cherries are extremely efficient, if one or more plungers in a pitting head become misaligned, a large number of pits may pass before corrective action is taken. While x-ray imaging has the potential to detect pits, traditional commercially available equipment is expensive and bulky, and implementation on the processing line is cumbersome. An x-ray inspection system using an array of photodiode based x-ray detectors in a linescan configuration whose outputs are combined to produce a one dimensional signal would be simpler, faster, and more economical. The data collection process is then reduced from a two dimensional image to a much simpler one dimensional signal, resulting in faster and simpler processing and classification. An algorithm designed to differentiate unpitted from pitted cherries for such a system yielded recognitiothe unpitted cherries, with a total error rate of 3.5%. When the a of pitted fruit, 100% of pitted cherries were detected with a orientation is controlled after pitting, total error is reduced to 1%.

Comparison of Workability of ZK60A Alloy Depending on Casting Methods

In this research, the effect of casting methods on the workability of magnesium alloy ZK60A was investigated by comparing two different billets, fabricated by semi-continuous casting and die casting. To determine the workability of the materials, uniaxial compression tests were conducted at different elevated temperatures and strain rate of 0.01/s. In addition, the X-ray inspection system and electron backscatter diffraction (EBSD) were employed to compare their internal defects and microstructures, respectively. The workability of ZK60A depending on the casting methods is discussed based on the obtained experimental results.

스테레오 X-선 검색장치를 이용한 이중물체 형상복원 연구

스테레오 X-선 검색장치는 기존의 대상물의 단면 정보만을 제공하는 검색 시스템보다 대상체에 대한 추가적인 정보를 제공하여 검색 효율을 높이기 위해 고안되었다. 이를 위하여 선행연구를 통해 스테레오 X-선 검색장치를 개발하고 기하학적 구조개선, 단일 오브젝트에 대한 윤곽선 정합 및 볼륨기반 형상복원 연구 등을 수행하였다. 본 논문에서는 선행 연구를 통해 개발된 스테레오 X-선 검색장치를 개선하여 정밀한 제어를 통해 두 개의 중첩 대상물을 스캔하여 대상체의 외형분리 복원을 위한 연구를 수행하였다. 중첩된 두 종의 대상체에 대한 외형정보를 분리 복원하기 위하여 벡터정보의 거리값을 계산하여 내 외부 복셀을 분리하고 중첩 부분에 대한 제거는 Z축을 기준으로 임계치를 두어 외형정보를 복원하기 위한 연구를 진행하였다. 본 연구의 결과는 3차원 스테레오 X-선 검색장치에 대한 스캔영상의 형상복원 알고리즘 개선을 통해 제한된 스캔환경에서 집적화된 대상체의 검색을 가능하도록 할 것이다. The Stereo X-ray inspection system is designed for effectively providing the additional information of objects than the conventional inspection system that offers only 2D cross-section of objects. We studied the geometric improvement of the stereo X-ray inspection system, the stereo matching algorithm of the single object using the edge and the volume reconstruction method for the inspected object. In this paper, we conduct a matching algorithm to find the correspondences between the images and reconstruct 3-D shapes of real objects using the stereo X-ray images. Also, we apply a new 3D reconstruction algorithm for the discrimination of two objects. For the separation of the overlapping objects, we calculate the vector of the object and divide inner and outer voxel of objects. And for the elimination of the overlapping area, we study the reconstruct 3D shapes using the threshold based Z-axis. The experimental results show that the proposed technique can enhance the accuracy of stereo matching and give more efficient visualization for overlap objects in the restricted environment.

Effects of Ultrasonic Power and Time on Bonding Strength and Interfacial Atomic Diffusion During Thermosonic Flip–Chip Bonding

In this paper, bonding strength of thermosonic flip-chip (FC) bonding was tested by a Dage 4000 bonding tester, atomic diffusion of bonding interfaces was detected by a scanning transmission electron microscope, and deformation of the bumps was observed by X-ray inspection system. Experimental results show that moderate ultrasonic power (about 4 W) results in higher shear strength of FC interfaces, while excessively high ultrasonic power induces larger displacement of vibration to damage bonding performance. Appropriate ultrasonic bonding time (about 100 ms) leads to the optimal thickness of atomic diffusion at the interfaces (about 200 nm) and better bonding bump shear strength with an average of 75 g. Overlong ultrasonic bonding time obviously aggravates the deformation of the bumps, which reduces bonding precision, thickens the thickness of atomic diffusion at the interfaces and damages the bonding strength. So, optimized parameters of ultrasonic power of 4 W and ultrasonic bonding time of 100 ms are proposed to improve the quality and performance of FC bonding.

Calculation of Effective Atomic Number and Normal Density Using a Source Weighting Method in a Dual Energy X-ray Inspection System

Calculation of Effective Atomic Number and Normal Density Using a Source Weighting Method in a Dual Energy X-ray Inspection System

Powerful x|act: software now available for GE’s phoenix high-resolution X-ray inspection systems

Powerful x|act: software now available for GE’s phoenix high-resolution X-ray inspection systems

A dual-energy linac cargo inspection system

X-ray inspection systems for cargo containers, capable of performing Z analysis, are an actively evolving type of equipment for cargo inspections [1–3]. A linear electron accelerator with fast energy tuning, operating in the mode of interlacing low- and high-energy electron pulses, has been developed for use in such a system. The output electron energy in this accelerator can vary in the range of 3–15 MeV under software control. An X-ray radiographic image of a container is obtained in a monoenergetic mode with a beam energy of 9 MeV. Pulses with energies of 4 and 9 MeV are used to recognize materials inside a container (i.e., perform Z analysis). The standing-wave linear electron accelerator operates at a frequency of 2856 MHz, its pulse repetition frequency with different energies is 240 Hz, the pulse duration is 10 μs, and the beam energy in each pulse is >10 J.

Design, development, testing and deployment of theworld's first fully automated individual body armor x-ray inspection system

With the onset of conflict and great troop deployments into South West Asia in 2003 during Operation Iraqi Freedom, the Radiography Laboratory at the US Army ARDEC was approached to investigate the feasibility of designing an automated inspection system to examine the integrity of all the Small Arms Protective Insert (SAPI) ceramic armor plates currently in service. This amounted to on the order of 1 million units so the need for a high-throughput, fully automatedsystem was apparent; this included automated defect recognition (ADR) software and automated material handling (AMH). Among the most challenging imaging artifacts is the fine local variation that arises as a combination of imager noise, photon noise and as a result of the arrangement of the fibers themselves in the plate backing and cover material. In many of these cases, the crack indications are actually smallerthan the level of interference imposed by the fine local variations.

Employing a Cerenkov detector for the thickness measurement of X-rays in a scattering background

The variation in environmental scattering background is a major source of systematic errors in X-ray inspection and measurement systems. As the energy of these photons consisting of environmental scattering background is much lower generally, the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence. A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison. Furthermore, it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.

Image capture and processing for 3D X-ray inspection system

Image capture and processing for 3D X-ray inspection system

Radiography simulation on single-shot dual-spectrum X-ray for cargo inspection system

We propose a method to identify materials in the dual energy X-ray (DeX) inspection system. This method identifies materials by combining information on the relative proportions T of high-energy and low-energy X-rays transmitted through the material, and the ratio R of the attenuation coefficient of the material when high-energy are used to that when low energy X-rays are used. In Monte Carlo N-Particle Transport Code (MCNPX) simulations using the same geometry as that of the real container inspection system, this T vs. R method successfully identified tissue-equivalent plastic and several metals. In further simulations, the single-shot mode of operating the accelerator led to better distinguishing of materials than the dual-shot system.

Characteristics of Isotropically Conductive Adhesive (ICA) Filled with Carbon Nanotubes (CNTs) and Low-Melting-Point Alloy Fillers

A new class of isotropic conductive adhesive (ICA) using a carbon nanotubes (CNTs) and a low-melting-point alloy (LMPA) fillers has been developed. We investigated the fundamental materials characteristics including curing behavior and temperature-dependant viscous property of ICA. In addition, the morphology of conduction paths in each ICA was investigated using X-ray inspection systems and an optical microscope. Mechanical and electrical characteristics of formulated ICAs were determined and compared with those of three kinds of conventional ICAs filled with Ag flakes. The CNT-filled solderable ICA formed good metallurgical interconnection between upper and corresponding lower electrode. In addition, the results indicated that the CNT-filled ICA exhibit lower electrical resistance and higher mechanical strength, as compared with those of conventional ICAs.

X선 영상의 에지 추출을 통한 플립칩 솔더범프의 접합 형상 오차 검출

The technology to inspect and measure an inner structure of micro parts has become an important tool in the semi-conductor industrial field with the development of automation and precision manufacturing. Especially, the inspection skill on the inside of highly integrated electronic device becomes a key role in detecting defects of a completely assembled product. X-ray inspection technology has been focused as a main method to inspect the inside structure. However, there has been insufficient research done on the customized inspection technology for the flip-chip assembly due to the interior connecting part of flip chip which connects the die and PCB electrically through balls positioned on the die. In this study, therefore, it is implemented to detect shape error of flip chip bonding without damaging chips using an x-ray inspection system. At this time, it is able to monitor the solder bump shape by introducing an edge-extracting algorithm (exponential approximation function) according to the attenuating characteristic and detect shape error compared with CAD data. Additionally, the bonding error of solder bumps is automatically detectable by acquiring numerical size information at the extracted solder bump edges.

Self-Organized Interconnection Process Using Solderable ACA (Anisotropic Conductive Adhesive)

In this paper, we discuss our design of a new class of low-melting-point alloy (LMPA)-filled anisotropically conductive adhesives (ACA) and a self-organized interconnection process for using these adhesives, and we demonstrate a good electrical conduction for the process. Flow, melting, coalescence, and wetting characteristics of LMPA fillers in the ACA facilitate this process. In order to exploit good coalescence and wetting characteristics of LMPA fillers, the polymer matrix has a sufficient fluxing capability against oxide films of both LMPA fillers and electrode materials. Furthermore, it is essential that the polymer have a low viscosity level around the melting point of the incorporated LMPA to achieve a good electrical conduction path. In order to study coalescence and wetting characteristics, we formulated two types of ACA with different volume fractions of LMPA filler (10 vol% and 40 vol%). Our test board had an 18-mm thick Cu line-type pattern (10 mm � 0:1 mm) and an area array-type pattern (square type: 0:1 mm � 0:1 mm, circle type: ’, 0.1 mm) with five different pitches (50 mm to 250 mm). We measured thermal properties of the ACA by differential scanning calorimetry (DSC), and we determined a temperature profile for the interconnection process. We then monitored coalescence and wetting characteristics of LMPA fillers and morphology of conduction path in ACA by using a microfocusing X-ray inspection system and an optical microscope. We determined that the developed LMPA-filled ACA have good coalescence and wetting characteristics regardless of pattern types. In addition, we were able to achieve a good electrical conduction path because of the coalescence and wetting characteristics of the LMPA fillers in the ACA. [doi:10.2320/matertrans.MF200918]

Hybrid Interconnection Process Using Solderable ICAs (Isotropic Conductive Adhesives) with Low-Melting-Point Alloy Fillers

In order to overcome several crucial limitations to the traditional electrically conductive adhesive bonding used in the electronics field, a novel low-melting-point alloy (LMPA)-filled ICA (Isotropic Conductive Adhesive) was synthesized. Also, a hybrid interconnection process using it was developed, which can be achieved by melting-coalescence-wetting behavior of LMPA fillers in ICA. In order to ensure excellent coalescence and wetting characteristics of the LMPA filler particles, the fluxing capability of the resin should have been sufficient to remove the oxide layer on the surfaces of the filler particles and the electrode materials. The effect of reductant on the hybrid interconnection formation was examined. ICAs with and without reductant were formulated with a 40% volume fraction of filler. The QFP chip had a size of 14 � 14 � 2:7 mm and a 1 mm lead pitch. The test board had a 18 mm thick Cu daisy-chained pattern. Thermal characteristic of the ICA was observed by differential scanning calorimetry (DSC), and the temperature-dependant viscosity characteristic of the polymer matrix was observed by torsional parallel rheometer. Based on the results, the reflow profile of the interconnection process was determined. The dipping interconnection method was applied in the QFP bonding process. After the QFP bonding process, the electrical characteristic of ICA was measured with a multimeter. The wetting, bondability, coalescence characteristics of the LMPA filler particles and the morphology of the conduction path were observed by microfocus X-ray inspection systems and optical microscopy. As a result, the LMPA-filled ICAs with reductant had stable contact resistance, forming the metallurgical interconnection. A good electrical conduction path was achieved with the coalescence and wetting characteristics of the molten solder particles in the ICA. [doi:10.2320/matertrans.M2009109]

Nano-Focus X-Ray Inspection Systems and Its Application

Nano-Focus X-Ray Inspection Systems and Its Application

Application of a new image segmentation method to detection of defects in castings

X-ray-based inspection technique is well applied to identification and evaluation of internal defects in castings, such as cracks, porosities, and foreign inclusions. Combining X-ray inspection with digital image processing and automatic image assessment is now the preferred approach for the continuous inspection of castings. However, in practical application, the quality of the X-ray image is poor. Under the circumstances, many classical thresholding methods usually cannot obtain ideal segmentation results. In this paper, we propose an effective segmentation method for the detection of typical internal defects in castings derived for an X-ray inspection system. The proposed method takes advantage of the fuzzy set theory and bound histogram and presents fuzzy exponential entropy for object and background according to the fuzzy sets and gray-level distribution of the image. The ideal threshold is obtained by maximizing the fuzzy exponential entropy associated with the distribution of the object and background classes in the bound histogram. Experimental results indicate that the proposed method is a powerful method to analyze images derived from X-ray inspection for automatically detecting typical internal defects in castings.

A Feasibility Study of X-ray Inspection System Using 90° Compton Scattering

A X-ray inspection system, a 90° Compton scattering inspection system coupled with a dual energy method, has been studied, which can directly give the effective atomic number of an unknown object. The 90° scattered signals by irradiating dual energy X-ray beams are measured and used to identify the unknown object hidden among other objects. Many simulations were carried out to verify the feasibility of this work with the illicit materials hidden in many kinds of sample geometries. From the simulation results, the dual energy beam method proposed in this study can find out the effective atomic numbers of the illicit materials. In the cases having simple geometry, all the relative differences between the calculated effective atomic number and the true value are shown to be less than 6.5 %. The feasibility of the dual energy beam method is also verified by scattering experiments using many kinds of sample geometries with TNT simulant. X-ray beams filtered by the ISO standard are used as the radiation source. A narrow detector collimator is employed in front of the detector for an accurate measurement of 90° Compton scattering signals. In the simple geometries containing TNT simulant, it was found that the relative differences between the reference and calculation results were less than 10%. According to the simulation and experiment results, the 90° Compton scattering inspection method coupled with a dual energy method will be effective to find the properties of unknown objects.

X-Ray Radiation Effect in DRAM Retention Time

For quality verification, an X-ray inspection process is commonly being used for evaluating obscured and defective solder joints in surface-mount technologies, such as ball grid arrays and flip chips. Integrated circuits subjected to any form of radiation, i.e., ionizing or nonionizing, may incur some amount of damage depending on the absorbed dose. Though most X-ray inspections for high-quality imaging require ionizing dose amounts that are considered inconsequential for device failure or non-functionality, the degree of latent damage must be carefully considered. This paper discusses X-ray-induced vulnerabilities of high-density dynamic random access memory exposed to low ionizing radiation levels typical in X-ray inspection systems. We look at critical parameters and their sensitivity in relation to varying dose amounts of X-ray irradiation. In consideration of different methodologies of reducing radiation dose amounts and limiting device exposure, we propose a procedure for attenuating potentially harmful X-ray radiation levels while preserving quality images.

Improving Automatic Detection of Defects in Castings by Applying Wavelet Technique

X-ray-based inspection systems are a well-accepted technique for identification and evaluation of internal defects in castings, such as cracks, porosities, and foreign inclusions. In this paper, some images showing typical internal defects in the castings derived from an X-ray inspection system are processed by some traditional methods and wavelet technique in order to facilitate automatic detection of these internal defects. An X-ray inspection system used to detect the internal defects of castings and the typical internal casting defects is first addressed. Second, the second-order derivative and morphology operations, the row-by-row adaptive thresholding, and the two-dimensional (2-D) wavelet transform methods are described as potentially useful processing techniques. The first method can effectively detect air-holes and foreign-inclusion defects, and the second one can be suitable for detecting shrinkage cavities. Wavelet techniques, however, can effectively detect the three typical defects with a selected wavelet base and multiresolution levels. Results indicate that 2-D wavelet transform is a powerful method to analyze images derived from X-ray inspection for automatically detecting typical internal defects in the casting