Research On Intelligent Diagnosis And Visualization Technology Of PCB Fault

With the development of science and technology, and increasing demand for printed circuit boards, on-board electronic circuit system is also becoming more and more complex, fault diagnosis for PCB board is becoming high strict before they leave the factory. How to quickly and effectively detect the quality of the PCB board has become a key problem which production enterprises have to pay attention to. However, because the traditional detection methods exist to large labor intensity, poor reliability(prone to defaults such as missing detection and false detection) and other shortcomings, so the intuitive and efficient intelligent detection method will gradually replace the manual method, which has become an inevitable trend.This paper studies intelligent diagnosis and visualization technology of PCB. Firstly it introduces the background of PCB fault diagnosis technology and its research significa nce. It describes the fault diagnosis technology of PCB, including the PC B fault classification and fault diagnosis methods on PCB.Then, it emphasis on the PCB function test method which is used in this paper. Because the current PCB’s traditional fault diagnosis technology is complicated and not intuitive, this paper proposed the PCB visualization fault diagnosis system, which is based on PLC and Lab VIEW software. The system will use Lab VIEW and PLC as the main development platform. In order to solve the problem of PCB precise localization of fault component s, this system uses the Visual C++ 6.0 to pack Visio 2007 Active X drawing Control, and to embed the Active X Control into Lab VIEW. As a result, the system could define the positions of the fault components by friendly Lab VIEW’s human-computer interface so as to realize the visualization of the system. In order to establish the intelligent diagnosis and visualization technology of PCB fault model more better, this paper also introduces Hidden Markov Model(HMM). According to the three basic problems of HMM(including assessment questions, decoding problem and training problem), and the corresponding ways to solve these three problems(including Backward algorithm, Viterbi algorithm and Baum-Welch algorithm), this paper would make a detailed description. In order to solve the problem of the establishment and traning of HMM’s initial parameters, this paper introduced the Genetic Algorithm and Time Correlation HMM(TC-HMM). Then, this paper respectively introduced the algorithm genetic coding, the fitness function, the genetic operator and the design of TC-HMM. In order to describe the building of the intelligent diagnosis and visualization technology of PC B fault system more clearly, this paper focuses on the realization of the fault diagnosis method, which is based on the combination of genetic algorithm and TC-HMM. Finally, Genetic Algorithm is used to improve and optimize the TC-HMM parameters’ initialization and training so as to build the intelligent PCB fault diagnosis model, which is used in this paper. At last, in order to test the proposed algorithm and the established model’s comprehensive performance, the experimental platform of the intelligent diagnosis model is set up. The practical results show that the proposed diagnosis system can reach the expected design purpose, it can improve the efficiency of fault diagnosis and realize the visualization of fault location. The system has the characteristics of high automation degree, simple operation, intuitive, etc. This system is suitable for PCB batch testing.