The PCB Board Level EMI Automatic Monitoring System Based On Image Positioning

With the continuous development of electronic technology, the circuit working frequency increasing, the circuit board level density is more and more big, but it comes with EMC problems.PCB is the basic unit of electronic products, the electromagnetic radiation interference is whether more than the limit value or not, it’s must be focused on electronic product design engineers. And build a monitoring system can intuitive understanding of EMI distributed on PCB, also it can effectively help design engineer to solve the problem from the source EMC. In this paper, image positioning technology and electromagnetic interference of automatic acquisition and processing technology organically, and based on the above background, this paper designed a set of PCB board level EMI automatic monitoring system based on image positioning.The automatic monitoring system with the host computer and mainly control three parts: the image acquisition module, the two-dimensional motion platform, and the spectrum analyzer. Each part, and be controlled by it. First of all, through the image acquisition module, filming the PCB to be tested for the later image positioning; Then using the two-dimensional motion platform carrying the probe, serpentine scanning of PCB. At the same time, the host computer read pectral data of each position from the spectrum analyzer. Finally, to deal with the data combining with the image positioning information, visually display the electromagnetic interference information in color images, and than form the test report.This article is divided into six parts: First, the PCB board level EMC automatic monitoring system based on image positioning are summarized, and simply introduced thetwo-dimensional motion platform. Second, the command of the stepping motor in the image acquisition module and screw linear guide principles are described. Third, this article introduced the principle of edge detection, and the image positioning after edge detection. Fourth, the magnetic field probe model was led out through the transmission line theory, the upper and lower shielded coplanar waveguide theory and Faraday’s law of electromagnetic induction, at the same time we use the HFSS simulation to optimize, finally carry out physical production and testing. Fifth, it introduced the construction of automatic monitoring system platform, including serial communication, data processing, interface design etc.. And the two kinds of PCB were tested, the test results can be visually displayed the importance of EMI, because it can save development cost and time. Sixth, for the purpose of this article summarize and prospect.