Information Technologies based on Wavelet Transform for Soldered Joints Diagnostic of Printed Circuit Boards

Abstract

In modern instrumentation, the number of soldered joints in printed circuit boards can reach several thousand. Diagnostics of the soldered joints defects within the optical wave length range is carried out using automated diagnostic systems. A number of stages of the existing information technologies for such systems are implemented on the basis of target functions extremum search using the gradient estimation. In the large batches of products production, the use of expensive automated diagnostic systems within lighting subsystems and high cost positioning are justified. These subsystems can provide improved noise immunity. However, in conditions when small batches of products are produced, and at some stages (for example, when positioning by comparison with a standard/prototype images) in general, such objective functions can be noisy and can be multi-extremes. For such cases, information technologies based on methods of enhanced noise immunity are required. Such an increase in noise immunity can be provided by methods using wavelet transformation. For this purpose, information technologies were proposed using wavelet transformation-based procedures that improve noise immunity and reduce the error of procedures in the diagnostic systems of printed circuit boards and their soldered joints.