Design Of Wafer Positioning Visual Inspection System

A dicing machine is an automated production facility used by electronic component manufacturers to align wafer wafers on a tray and cut them into individual small dies.The traditional dicing machine position calibration has no machine vision function.The tilt correction and positioning work is still done by amplifying and then manually adjusting the motor to complete the aligning work.This manual aligning work has many defects,such as cumbersome operation,high precision,high error and other defects.Therefore,it is necessary to specifically study a set of wafer positioning visual inspection systems with high degree of automation,high detection accuracy and fast running speed to meet the requirements of existing productivity.In view of the above situation,the program designed and developed a new wafer visual inspection and positioning system,which realizes the positioning of the wafer before the dicing machine cuts the wafer.This scheme designs a on-line wafer positioning and visual inspection system integrating image acquisition,data processing,mechanical movement and information display.The system software and hardware implementation mechanism is briefly described.The machine vision based wafer positioning algorithm is elaborated.The content of the research is mainly focused on the following aspects:First of all,combined with the existing equipment of the existing dicing machine to add a machine vision hardware system,the hardware system includes two aspects of the imaging system and the motion control system.We select the optics of the camera,lens and light source according to the actual needs of the positioning and correcting.We also select the appropriate motion platform and motion control card according to the motion accuracy requirements.Secondly,according to the requirements of human-computer interaction,a visual interface is designed to control the start and stop of the hardware part.In order to make the interface easier to operate and convenient to debug,some practical interactive tools are designed to be convenient for users and developers.Asynchronous programming is used to make the overall control more in line with user habits,and the communication method between software is explained.Thirdly,the rough square algorithm based on multiple template matching is studied in detail,and the squared positive algorithm based on hough transform and morphology algorithm.The application principle of various matching algorithms,the selection of important parameters and the comprehensive comparison of each matching algorithm are elaborated.The application flow,experimental success rate and accuracy of the accurate matching algorithm are described.Fourthly,the calibration of the camera is completed,and the initial cutting position of the wafer in the world coordinate system is positioned,and the laser knife starts to perform precise cutting along the channel.After the laser knife is cut a single time,the cutting edge of the laser knife is detected and corrected,and the new cutting position is adjusted in real time.Finally,based on the characteristics of the wafer and the current status of the dicing machine,a set of on-line positioning and positioning system of the wafer was studied,and a large number of tests were carried out on the system.Eventually,the total time of positioning and pendulum(including mechanical motion)is less than 10 s,the pendulum error is less than 0.001°,the positioning error is less than 5μm,and the comprehensive success rate of positioning and square is greater than 96%,which basically meets the requirements of enterprises.