| FPC(Flexible Printed Circuit)is a printed circuit board with high reliability and good flexibility,and it has found an increasingly wide utilization.However,the FPC defect detection methods currently used by most enterprises keep in the ways of human visual test and offline ATE(Automatic Test Equipment),which reason is that the mature online FPC defect detection technology still doesn't appear at home and abroad.Compared with the traditional rigid PCB,FPC detection is difficult due to its imaging deformation defect,so the rigid PCB defect detection algorithm can't be used for FPC.Therefore,an online FPC defect detection algorithm needs to be specially studied to overcome FPC deformation influence.Aiming at the various keyboards' FPC bare plates on industrial production line,the method in this paper detected online by image processing on four common defects such as flaw,bump,open circuit and short circuit.This paper aimed to build an online FPC defect detection method with high automation,quick test speed and low rate of error detection,to meet the existing capacity requirements.The research contents of this paper focused on the following aspects:Firstly,the hardware part of online FPC defect detection system was designed according to FPC product line,and the software was designed according to FPC character and function need.Secondly,the asynchronous zoom template matching method in combination with frame character was used to realize FPC special-shaped defect detection which could greatest degree reduce the influence of FPC overall deformation to local.Thirdly,the morphological method was ingeniously used to realize FPC flaw and bump defect detection.By comparing the connected domain number before and after morphological operations,the defect and bump could be quickly prejudged and located so that FPC deformation influence could be dispensed.Finally,FPC open circuit and short circuit defect detection method based on feature tracking.After using feature tracking to exclude the normal end points and branch points,the FPC open circuit and short circuit defect detection was realized to reveal the abnormal points.The scope of feature tracking could be set according to the actual deformation degree.In the end,according to the features of the keyboard FPC silver wire and the current situation of FPC production lines,the FPC hardware imaging system was built,and a set of online FPC defect detection method was studied to achieve the detection with 460 mm * 750 mm maximum size and 0.3mm minimum line width.The method's test time was within 3000 ms and the average detection error rate could reach 0.68%. |
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