Structural Analysis And Optimization Of High-Speed Precision AOI Equipment

With the PCB assembly density becomes more compact and the electroniccomponents’ size becomes much smaller, traditional human vision inspection isunable to satisfy the detection precision and speed of microelectronics manufacturing,so the automatic optical inspection system (AOI) becomes the main inspectionequipment of SMT. The market competition among AOI equipments turns into muchfiercer, only efficient, stable and accurate equipments can win the favor of themarket, and occupy more market share. Traditional design methods are based onexperience, analogy and statics, so the produce design cycle is very long, andproduces’ dynamic performance could not be improved. Therefore, it is particularlyimportant for improving the market competitiveness of manufacturers to use advanceddesign methods. With advanced design methods, engineers can forecast equipmentsperformance during the equipments are still designed, and modify initial structure toreduce quality, control vibration and improve operation speed and precision based onthe forecast result.On the base of analyzing and summarizing related research, this thesis appointsthe off-line automatic optical inspection machine（AOI）which is produced by ourenterprise partner as the research object, and improving its dynamic performance,reducing its weight as the optimization goals. Four main parts of the machine, namelythe rack, the beam, the detector, and the flat board are optimized. Firstly, the machineare studied with modal analysis by ANSYS Workbench, the finite element analysissoftware, to acquire its dynamic performance and weaknesses. Secondly，based on theabove analysis result, model test is operated on the machine. The agreement betweenfinite element analysis and modal test proves the accuracy of finite element model andits analysis result. The finite element analysis offers reliable basis to the nextoptimization design. Then the four parts are studied with statics analysis and modalanalysis by ANSYS Workbench. The structure sizes of the rack and the beam areoptimized with response surface method and multi-objective genetic algorithmmethod. The unit structure theory is used to design the reinforced rib structure of the light-source fixed plate. The structure sizes of the fixed plate are also optimized. Theflat board’s framework is designed by topology optimization, its structure sizes areoptimized by response surface method and multi-objective genetic algorithm method.Finally, the static and dynamic performance of the optimized machine is analyzed andcompared with the original one. The results show that the presented optimizationachieves weight reduction of10%with desired static and dynamic performance, andhence has realized the expected target.