| In the transition of industrial production from mechanization to intelligent automation,the burn-in screen machine that undertakes the task of screening electronic components has been widely used.However,due to the needs of element screening technology,the power supply and power supply lines of burn-in screen machine need to work in a closed environment with high temperature difference and strong magnetic field for a long time,the actual stress exerted on the electronic components may deviate greatly from the set value or even completely fail.Therefore,in order to examine the actual ability of the burn-in screen machine to undertake the screening task,the on-line detection of the voltage and current output by the burn-in screen machine is required.Because the temperature inside the burn-in screen room constantly changes between-55°C and 80°C and there are some strong electromagnetic interference signals,and the voltage detection accuracy can reach 0.05%,the current detection accuracy can reach 0.07%,and the general measurement and test system is difficult.To meet the requirements,it is necessary to develop and design a special inspection system.The main research contents of this article are as follows:Firstly,aiming at the high precision requirement of on-line detection system,this topic researches systematic error theory in advance,determines the error distribution principle and error synthesis method of the system,and guides the design of the overall system and hardware circuit of the system.At the same time,the thermal design and electromagnetic shielding technology of electronic equipment were studied.Based on the characteristics of the internal environment of burn-in screen room,the system was designed to resist temperature and electromagnetic interference.Based on the above research results and system requirements,the overall design of the system was completed.Secondly,the overall hardware structure of the online detection system is designed.The hardware circuit is divided into five modules: analog signal conditioning unit,isolation unit,data acquisition unit,STM32 minimum system and communication unit.The design ideas,circuit structure of each module and the choice of devices are discussed in detail,and calculate the theoretical errors caused by various components in the analog signal conditioning unit,which is the main source of systematic errors,so as to provide the necessary guarantee for systematic errors meeting the technical requirements.Then,the μCOS-II real-time operating system is transplanted in the microcontroller,and designs independent user functions on this operating system to divide the system functions into different modules to simplify the management of the system.At the same time,based on Lab Windows/CVI developed and designed the system's PC software,to achieve the system's automatic testing functions and online detection functions.Finally,the data acquisition function,temperature control function and communication function of the system are verified,and a system test platform is set up to complete the overall function debugging of the system and the calibration of the measurement data.The system error is measured and the performance of the system is evaluated in the field environment where the burn-in screen machine is operated.The experimental results show that the on-line detection system designed in this paper can complete the on-line detection task of the electronic components burn-in screen machine under the environment of high temperature difference and strong magnetic field in the burn-in working room,and the performance indicators meet the technical requirements. |
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