Stability investigations of automatic X‐ray inspection systems

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.