Search results

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.

The purpose of this paper is to present improvements in X‐ray equipment, which are leading to wider use.

Developments in X‐ray sources and detectors are described. This is followed by a review of the more innovative equipment available for security and industrial applications.

Technological developments have produced smaller, lighter X‐ray systems and extended their applications to on‐site work. Multiple wavelength systems distinguish between different materials, and stereo systems remove ambiguities from X‐ray security imaging and allow 3D gauging of industrial components.

The paper highlights the availability of portable X‐ray systems and explains the underlying technology.

The aim is to focus on the application of X‐rays in the failure analysis of electronic devices and systems, with an emphasis on X‐ray radiography and X‐ray spectroscopy.

The theory behind X‐ray radiography and X‐ray spectroscopy is reviewed, and relevant case studies are used to illustrate the application of these techniques in the failure analysis of electronic devices and systems.

Examples from recent case studies are given.

The paper provides an introduction to X‐ray methods for engineers working on the failure analysis of electronic devices and systems who may be unfamiliar with these techniques.

The purpose of this paper is to develop a new method of evaluating the present state of X‐ray machines used in the electronics device manufacturing industry.

There are several kinds of failures that can only be detected by means of X‐ray inspection. The capabilities and properties of such machines, however, alter over a period of time. The effects of these changes are rarely published and when they are, the significance and reliability of the results produced depends very much on the state and capabilities of the machines in question.

The effectiveness and appropriateness of the present methods of calibration have been investigated. The optimization of the prevalence and effectiveness of these calibrations is described. Suggestions are also made as to the necessary adjustments or repairs that are required to reach the ideal optimized state of X‐ray machines. A scientifically substantiated method is also presented that can be efficiently employed in practise during automated X‐ray inspections of electronic devices.

In this paper, a new method of testing automated X‐ray inspection systems is introduced. It is clear that the method currently used by many engineers and inspection system manufacturers is not in itself sufficient, as they do not test grey‐scale and positioning stability in relation to changes that occur over time. Further, there is no evidence that numerical testing of the image quality takes place. Detailed investigations have been carried out to find the best methods to measure these parameters.

The purpose of this paper is to develop a realistic computational model of carbon fibre reinforced polymer (CFRP) structures dedicated for in-silico investigations of the use of X-ray-based imaging techniques as non-destructive testing (NDT) of CFRP parts.

CFRPs contain layers of carbon-fibres bundles within resin. Bundles’ orientation in the different layers is arranged with respect to each other at a well-defined primary direction. In the model, the bundle was simulated as a circular cylinder. The resulted model is a stack of layers of unidirectional bundles having orientation of 0°/90°/45°/−45°. Two CFRP structures were modelled: a flat CFRP part and a real shaped CFRP clip. A porous layer and non-carbon fibres were inserted within each model, respectively. X-ray projection images were generated with a dedicated simulation programme. Three setups were investigated: radiography, tomosynthesis and cone-beam CT (CBCT).

Results showed that porosity and non-carbon fibres were visible with all X-ray-based techniques. Tomosynthesis and CBCT, however, provide higher quality image of defects.

The CFRP computational model is a valuable tool in design, testing and optimization phase of X-ray-based imaging techniques for use in NDT of composite materials. Simulated images are generated within a short time; thus results from virtual optimization and testing are obtained very fast and at low cost.

An innovative computational model of CFRP structures, dedicated for X-ray imaging simulations, has been developed. The model is characterized by simplicity in its creation and realistic visual appearance of the produced X-ray images.

To accommodate increasing levels of device integration at the chip level, circuit line densities in electronic packages are continually increasing. Greater circuit line density, in turn, necessitates a corresponding increase in package‐to‐board interconnection density, with I/O counts expected to reach over 600 by 1995. In conjunction with the upward trend in I/O counts are a complementary upward trend in clock speed and an opposing downward trend in package sizes driven by the need to provide more functionality in less space, particularly in notebooks and PCMCIA cards. To satisfy the requirements of increased I/O counts and clock speed, and reduced package sizes, various package‐to‐board interconnection technologies are being developed, such as flip chip attach (FCA) using C4 joints. However, FCA interconnections have a disadvantage of being very difficult, if not impossible, to visually inspect. Though automatic test equipment (ATE) can determine whether the package is functional, it cannot determine the quality and reliability of FCA interconnections. Of the possible inspection techniques available to assess the quality of FCA interconnections — differential laser thermal analysis, acoustic microscopy and cross‐sectional X‐ray radiography — only cross‐sectional X‐ray radiography is capable of accurate, automated inspection of production volumes. This paper will first examine the requirements for inspecting FCA joints and will then describe the various inspection alternatives, outlining their advantages and disadvantages. Having described the potential advantage of one particular cross‐sectional X‐ray technique, digital tomosynthesis, the paper will conclude with some cross‐sectional images of FCA and SMT joints taken by a digital tomosynthesis system being developed for the inspection of FCA joints.

The purpose of this paper is to develop a novel automatic and accurate measurement technique for the volume of solder which is present in solder paste in pin‐in‐paste (PIP) technology and a calculation algorithm for predicting solder joint quality.

A new method is described for accurately determining the volume of solder alloy in solder paste that is present in and around the through hole, using X‐ray measurements (orthogonal view X‐ray images, instead of angle view), image processing and other calculations. In addition, various calibration tool constructions are investigated and a method is suggested for determining the calibration curve (for each solder paste) of an X‐ray machine.

A new calibration tool has been developed to accurately measure the calibration curve of X‐ray machines. Based on several tests, a fast and reliable image processing method for measuring the average grey scale of each pasted through hole is described. Numerous PIP solder joints have been created then analysed using the methodology. To verify the efficiency of the described methods, joints are soldered and inspected using cross‐sectioning and X‐ray imaging.

Calibration curve measurement of an X‐ray machine is done with the help of the developed tool for PIP technology. Orthogonal view X‐ray images are used to measure the volume of printed solder alloy (paste). During the image processing, circle fitting has been simplified to line fitting.

The X‐Ray fluorescence method of coating thickness measurement of ISO 3497, BS 5411 (A), DIN 50987, and ASTM B568–79 is discussed from a practical point of view. A brief illustration of the method's technical principles, advantages, applications, and example instrumentation is given together with some of the precautions to be taken.

The cardiomegaly can be determined by the cardiothoracic ratio (CTR) which can be measured in a chest x-ray image. It is calculated based on a relationship between a size of heart and a transverse dimension of chest. The cardiomegaly is identified when the ratio is larger than a cut-off threshold. This paper aims to propose a solution to calculate the ratio for classifying the cardiomegaly in chest x-ray images.

The proposed method begins with constructing lung and heart segmentation models based on U-Net architecture using the publicly available datasets with the groundtruth of heart and lung masks. The ratio is then calculated using the sizes of segmented lung and heart areas. In addition, Progressive Growing of GANs (PGAN) is adopted here for constructing the new dataset containing chest x-ray images of three classes including male normal, female normal and cardiomegaly classes. This dataset is then used for evaluating the proposed solution. Also, the proposed solution is used to evaluate the quality of chest x-ray images generated from PGAN.

In the experiments, the trained models are applied to segment regions of heart and lung in chest x-ray images on the self-collected dataset. The calculated CTR values are compared with the values that are manually measured by human experts. The average error is 3.08%. Then, the models are also applied to segment regions of heart and lung for the CTR calculation, on the dataset computed by PGAN. Then, the cardiomegaly is determined using various attempts of different cut-off threshold values. With the standard cut-off at 0.50, the proposed method achieves 94.61% accuracy, 88.31% sensitivity and 94.20% specificity.

The proposed solution is demonstrated to be robust across unseen datasets for the segmentation, CTR calculation and cardiomegaly classification, including the dataset generated from PGAN. The cut-off value can be adjusted to be lower than 0.50 for increasing the sensitivity. For example, the sensitivity of 97.04% can be achieved at the cut-off of 0.45. However, the specificity is decreased from 94.20% to 79.78%.

The paper aims to provide a simulation optimization solution to improve patient scheduling that accounts for varying ancillary service time such as x-ray to minimize patient wait time.

The two-step approach is to: identify patients' needs for ancillary services while scheduling appointments; and propose an algorithm to determine ancillary service time via simulation optimization. The main aim is to provide sufficient time between arrival at the clinic and the actual examination time for a patient to complete pre-visit activities without contributing significantly to patient wait time. Two case studies are included to demonstrate the approach.

Triaging at the appointment-scheduling time saves an average 17 minutes for physician's first consultation in a clinic day, and a 7 percent reduction on current average patient wait time for case 1. Case 2 results in a 9 percent reduction on average patient wait time. The scheduled ancillary service time depends on the frequency and the ancillary service time, and appointment slot design.

One limitation is the impact of modeling error on the account of ancillary service times and the modeling assumptions.

The proposed approach provides a studying method for clinic staff to account for ancillary services prior to physicians' visits for a better patient care. Two case studies demonstrated the practicability and promising results on reducing patient waiting.

This article presents a unique approach to considering the required ancillary services in outpatient scheduling system that minimizes patient wait times. The approach will strengthen the existing scheduling methods to allow the time for ancillary services.