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The initial excitement over increased solder joint densities, higher manufacturing throughput, and superior electrical performance brought forth by surface mount technology (SMT) has been replaced by frustrations over lower yields and the inherent difficulties of inspecting hidden solder joints. In the plated through hole (PTH) process, rework and inspection tasks were not only relatively easier tasks, but also less costly. The high cost of inspecting and reworking SMT assemblies dictates a rethinking of the assembly process. Increasing first time yields becomes the key to reducing SMT inspection and rework costs. In a high volume facility, a 100% visual inspection process is not feasible because of the high cost of inspection and rework. However, if a company intends to remain competitive, inspection and rework must be reduced without a sacrifice to final product quality. Realising that it is not possible to ‘inspect’ quality into a product, improved yield must result from a controlled process environment. By maintaining a controlled environment, one will be provided with lower inspection costs, lower rework costs, lower scrap and, in the final analysis, improved product quality. At the heart of any process control environment should be a real‐time process control system designed specifically to accommodate SMT process defects. Process monitoring is accomplished by locating and identifying SMT process flaws. These flaws will then be reported to a host system for statistical analysis. These are statistical data used to make timely adjustments to the various stages of the assembly process in a real‐time manner. Being able to monitor the production process objectively in real time, and detect hidden flaws accurately, are the keys to having a successful process inspection system. Automated X‐ray Inspection is gaining acceptance as a viable process monitoring tool, capable of detecting and reporting SMT process flaws, including those hidden flaws not reported with typical visual inspection systems. The purpose of this paper is to show how an Automated X‐ray Inspection system can be integrated into the SMT production process as a cost‐effective method for improving SMT yield.

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.

To present an overview of the research and development carried out by an EC Framework 6 part funded consortium, known as MICROSCAN, for the implementation of an in‐line PCB inspection prototype system that is capable of offering comprehensive defect detection.

Four non‐destructive testing inspection modules based on digital radiography (X‐ray) inspection, thermal inspection, automated‐optical inspection and acoustic inspection have been integrated to form a combined inspection system.

A proof in principle in‐line PCB inspection system, utilising four different inspection techniques, has been developed and demonstrated. The system is based on a generic mechanical, electrical and software communications platform culminating in a flexible system that enables the inspection modules to be used separately, together or interchanged to give the best results in terms of inspection coverage and inspection throughput.

In its current embodiment, the prototype is suited to inspection of high‐return PCBs, particularly those used in medical and aerospace products, rather than high‐throughput PCB production work. The X‐ray inspection module is the slowest inspection technique and combining four different inspection techniques reduces the inspection throughput of the whole system to that of the X‐ray inspection module. Further, trials and investigations need to be carried out to improve inspection throughput.

The novelty of the system is that it is the first time that four inspection techniques have been combined to give the capability of 100 per cent defect coverage.

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.

Electronic packaging technologies, such as pin grid arrays, increasingly small pitch surface mount, and double‐sided assemblies are all aimed towards the highest possible product density, with improved performance. The gap between inspection effectiveness and advances made in packaging technologies is becoming larger. As efforts proceed, to learn more about critical factors influencing reliability of solder joints, it is prudent to ensure that printed wiring assembly (PWA) design rules evolve to permit the broadest range of anticipated automated inspection requirements. The range of automated inspection technologies can all be made more effective through careful design of electronics for inspection. Significant opportunities lie in both PWA layout and design, as well as electronic component design, tolerancing, and standardisation. Many inspection issues are shared, but with increased recognition of digital radiography's unique capabilities; this discussion will emphasise X‐ray inspection issues.

FOLLOWING the talk given by Mr William C. Hitt of the Douglas Aircraft Company last June, which was reported in Aircraft Engineering for July, the S.L.A.E. organized a meeting at which the subject could be further discussed. Mr R. A. Fry was in the chair, and the first paper, by Mr William C. Hitt, was delivered by his son, Mr Lloyd Hitt.

X‐ray laminographic image can provide more useful information about the internal state of electronic packaging than x‐ray radiographic image does. Many kinds of laminographic system have been developed for obtaining the cross‐sectional image. Proposes an axial laminographic system, which can be constructed by usual automatic radiographic system without any rotating x‐ray head and detector system. Explains that this method can be implemented to make the usual radiographic x‐ray inspection system equal to the power of a laminographic system.