Large Scale And Flexible Printed Circuit Board Defect On-line Inspection System

Flexibility printed circuit board, a kind of bendable circuit board made by polyimide and polyester membrane. It has many advantages, such as, well flexibility, environment friendly,and is widely used in electric mechanical automatic control, intelligent devices, and so on. As a result of natural and environmental factors, circuit boards are prone to short circuit, open circuit, bulge and so on. At present, the traditional way of artificial detection is high cost, low efficient and accurate. Therefore, combining with actual defect types, the paper developed the large scale and flexible printed circuit board defect on-line inspection system.Firstly, the system selects the appropriate parameters of equipment for the construction of hardware platform. In the design, the main work is coordinating the imaging system resolution,sensitivity and speed, adjusting the light source position, working out the optimized solution through test and analysis for many times. What’s more, the transform measure from the CAD document of circuit board to the standard image is determined, including the transformation from the DWG file types of CAD file into Gerber format, acquisition of Gerber data,coordinate conversion from CAD space to imaging space of the standard circuit image,acquisition of standard size and corresponding coordinate data. Then the standard circuit board image is generated. Finally, according to standard size of circuit board and partial matching method, the detection algorithm is determined, including partial registration of silver wire,detection of defect and coordinate conversion method from image space coordinate to physical coordinate.According to the design, the large scale and flexible circuit board defect on-line inspection machine is produced. And through the test for many times, acquisition time is around 346 ms, real-time detection based on Gerber document costs around 2338 ms, detection accuracy can be up to 91.13%.The task from the CAD document to the image of the standard printing circuit board is before the detection work, which is time-saving. With the system,several kinds of common defects can be inspected effectively.