Speeding populated board inspection: a new technology

The need for automated populated board inspection stems from the desire to reduce the number of defective board escapes, and to improve the yield of the production line. There are two main goals of populated board inspection: (1) to detect and classify defects, (2) provide process control information. Although at first glance the goals may appear to be independent, they are actually very closely related through the technology used to perform populated board inspection. The current generation of inspection technology typically trades classification accuracy-and hence the ability to provide meaningful process control information-with detection ability and ease of implementation. So while the current generation of technologies may be able to detect a wide range of anomalies on the populated board, detection is not the same as classification. Detection without robust classification will not lead to improved production yields because the information needed to improve the process will not be collected. In this paper we briefly overview the current generation of inspection technology, presenting its weaknesses with respect to the two stated goals. In order to address these goals, a new approach to populated board inspection is described.