Probe Automatic Positioning Testing System Research Based On Machine Vision

Abstract:With the development of the microelectronics industry, Electronic components become smaller and more miniaturized. Test pads on the PCB are more intensive, the number of test probes is increasing, using the traditional way of mechanical slot positioned on the PCB board has become increasingly difficult, the requirements of solder joint alignment accuracy requirements are more to higher, for which Based on Machine Vision Technology has designed a complete probe test system to achieve the alignment between56probes and56joints. The main research work includes:1. Constructed an Automatic Positioning System includes including motion control systems, data acquisition systems, and vision systems. The accuracy of the design of x, y, z axes and the rotary table respectively are0.4μ m,0.5μm,0.4μm and0.08degrees. The vision system is fixed through rational design of lighting, camera and the building of CCD.2. Carried out software development for probe test system, including motion control procedures, image acquisition process, image processing, calling program. Based on virtual instrument software Lab VIEW, used the modular concept to develop motion control procedures; based on Matlab, developed the image processing procedures.3. Propose a new image processing algorithms to accomplish locate Coordinate. By Gaussian filtering, automatic threshold segmentation, opening and closing operation to remove blotchy and other interference information to achieve the target image features rectangular extraction; through the median filter, mean filter and Gaussian filter processing compares selected Gaussian filter most suitable image filtering. By extracting the rectangular perimeter contour based linear fitting rectangular fitting, calibration coordinate system to solve the coordinate information.4. Complete results of validation and automatic positioning function test probe test system. Design of experiments and proved3D platform horizontal x-axis (vertical axis y-axis) with respect to the translational direction ordinate (abscissa) and the test results of the impact angle is small, the precision of draw x、y and the direction of rotation respectively are7.6μm,7μm and0.066degrees, and derive the relationship between the test results and the conversion. PCB board by two automatic positioning tests to demonstrate the system to complete the probe and the PCB pads aligned and positioned to measure the performance of the PCB circuit resistance.All in all, the system completed the combination of motion control and machine vision, also can achieve precise alignment between probes and solder joints of PCB board.