To solve the problems of severe reflection caused by local high illumination and shadow areas in the visual inspection of IC (Integrated Circuit) devices, this paper innovatively designs a multi-annular array light-emitting diode (LED) light source system based on freeform surface reflectors. A comprehensive evaluation function that simultaneously optimizes the illumination uniformity and illumination efficiency on the receiving surface is established. The Taguchi method is applied to optimize four parameters of the system. Furthermore, the ANOVA method is used to confirm the effectiveness of the optimization experiment. Finally, the optimized light source system was experimentally validated in the IC chip detection system. The results showed that the illumination uniformity and the illuminating efficiency of the optimized multi-annular array LED light source system were improved by 13.6% and 48.5%, respectively, compared to the traditional LED light source. The verification in the IC chip detection system shows that the average accuracy of character recognition, pin shortage detection and weak scratch detection reaches 99.74%, 100% and 99.97%, respectively, which can fully meet the visual inspection lighting of IC devices.
Zhang et al. (Sun,) studied this question.