Research And Development Of The PCB Auto Locate Drill Based Optical Scanning

In the process of manufacturing Printed Circuit Board (PCB), every board has to be drilled based holes firstly. So the precision of based holes greatly influence the quality of PCB. Traditionally, PCB is loacated with the help of man's eyes, which inevitably influences the precition of location and the efficiency. Combination of optical technology and NC technology is currently a good way to solve this problem. This paper presents the R&D of the PCB auto locate drill based optical scanning.This thesis targets to discuss an application of combination with machine visual technology, machinery technology and NC technology in the R&D of machine for PCB manufacture. The design of machine includes image collection and process, control system, pneumatic system, programme of serial port communication and machine test. This dissertation composes of several parts, which are as follows. Firstly, the target of design and significance are also discussed. Secondary, the rule of design is provided. The components of machine and structure are all detailed. Thirdly, the choice of CCD vidicon is discussed. The match between optical camera lens and image collection card and PCB image influenced by intensity of illumination are all discussed too. Fourthly, this dissertation stresses the structure of control system, the choice of lower computer and the principle of communication between upper computer and lower computer. The choice of step motor and the control of step motor are discussed too. Finally, arithmetic of based holes is researched and analyzed. This mainly compares the hough transformation and the arithmetic of centroid. After that, arithmetic of arc, which combines strongpoints of the hough transformation and the arithmetic of centroid, is presented. The development of main programme for upper computer and the set of variables are expatiated. Four main modules of programme are presented too.Based on the results of machine test and feedback of customer, the R&D of machine may solve above problems. The main technology indexes may be fulfilled, such as amount of holes drilled per minute and precision of hole. Compared with congener machine made in China, this machine has the advantages of higher efficiency, higher precision, lower power dissipation and lower cost. This makes up shortage of current PCB manufacture.